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The effects of movement amplitude and contraction intensity on triceps surae and quadriceps femoris muscle function were studied during repetitive hopping. In vivo forces from Achilles and patellar tendons were recorded with the optic fibre technique from eight volunteers. The performances were filmed (200 Hz) to determine changes in muscle-tendon unit length and velocity. When hopping with a small amplitude (23° knee flexion during the ground contact phase), the Achilles tendon was primarily loaded whereas patellar tendon forces were greater in large-amplitude hopping (56° knee flexion). In spite of the different magnitudes of stretch in the quadriceps femoris muscle, the stretching velocity and activity patterns of the quadriceps muscle were similar in both conditions. Simultaneously performed electromyographic (EMG) recordings revealed that preferential preactivation of the gastrocnemius muscle was evident in both jumping conditions. The triceps surae muscle was strongly active in the eccentric phase of small-amplitude hopping. Results from hopping with small knee-joint displacement suggest that there may be a particular frequency and jumping height at which the elastic bouncing is best utilized and at the same time the concentric phase is most economical. Results also support earlier observations that the economy of the shortening phase must be compromised at some point in order to produce more power and improve the jumping height.
DAPIT (Diabetes Associated Protein in Insulin-sensitive Tissues) is a small, phylogenetically conserved, 58 amino acid peptide that was previously shown to be down-regulated at mRNA level in insulin-sensitive tissues of type 1 diabetes rats. In this study we characterize a custom made antibody against DAPIT and confirm the mitochondrial presence of DAPIT on cellular level. We also show that DAPIT is localized in lysosomes of HUVEC and HEK 293T cells. In addition, we describe the histological expression of DAPIT in several tissues of rat and man and show that it is highly expressed especially in cells with high aerobic metabolism and epithelial cells related to active transport of nutrients and ions. We propose that DAPIT, in addition to indicated subunit of mitochondrial F-ATPase, is also a subunit of lysosomal V-ATPase suggesting that it is a common component in different proton pumps.
Regardless of age or gender, resistance training or provision of adequate amounts of dietary protein (PRO) or essential amino acids (EAA) can increase muscle protein synthesis (MPS) in healthy adults. Combined PRO or EAA ingestion proximal to resistance training, however, can augment the post-exercise MPS response and has been shown to elicit a greater anabolic effect than exercise plus carbohydrate. Unfortunately, chronic/adaptive response data comparing the effects of different protein sources is limited. A growing body of evidence does, however, suggest that dairy PRO, and whey in particular may: 1) stimulate the greatest rise in MPS, 2) result in greater muscle cross-sectional area when combined with chronic resistance training, and 3) at least in younger individuals, enhance exercise recovery. Therefore, this review will focus on whey protein supplementation and its effects on skeletal muscle mass when combined with heavy resistance training.
In order to understand the possible mechanisms contributing to enhanced concentric performance in stretch-shortening cycle exercises in vivo the present study examined knee extension torque, EMG activity and fascicle length of the vastus lateralis muscle in maximal and submaximal human movements. Maximal concentric knee extensions (120 s-1) were done after pre-stretch and pre-isometric conditions by nine volunteers. During shortening at the knee angle of 115 (180 = extended) the knee extension torque was found to be greater in pre-stretch condition (272 vs. 248 Nm, p < 0.05) although the torque level prior to shortening was smaller than in pre-isometric condition (268 vs. 314 Nm, p< 0.05). At the moment of torque enhancement the EMG activity levels or fascicle lengths did not differ between the conditions. It is proposed that besides specific experimental conditions the present enhancement may be related to longer fascicle length prior to shortening (by 4.1 cm, p< 0.05) in pre-stretch condition and to modified length-tension properties. Fascicle length behaviour was found to play an important role also in unilateral, submaximal sledge-jump conditions where pre-loading was altered but the concentric net impulse and joint angular movements were the same. In repeated drop jumps with greater pre-load the changes in fascicle length were smaller than in the counter movement jump that was characterized by a lower force and activity level in the eccentric phase. Results from the present maximal and submaximal loading conditions suggest that the benefits of stretch-shortening cycle muscle function may come through different interactive mechanisms that may be task specific.
Background. Alfa-Hydroxy-isocaproic acid (HICA) is an end product of leucine metabolism in human tissues such as muscle and connective tissue. According to the clinical and experimental studies, HICA can be considered as an anti-catabolic substance. The present study investigated the effects of HICA supplementation on body composition, delayed onset of muscle soreness (DOMS) and physical performance of athletes during a training period. Methods. Fifteen healthy male soccer players (age 22.1+/-3.9 yr) volunteered for the 4-week double-blind study during an intensive training period. The subjects in the group HICA (n = 8) received 583 mg of sodium salt of HICA (corresponding 500 mg of HICA) mixed with liquid three times a day for 4 weeks, and those in the group PLACEBO (n = 7) received 650 mg of maltodextrin mixed with liquid three times a day for the same period. According to a weekly training schedule, they practiced soccer 3 - 4 times a week, had strength training 1 - 2 times a week, and had one soccer game during the study. The subjects were required to keep diaries on training, nutrition, and symptoms of DOMS. Body composition was evaluated with a dual-energy X-ray absorptiometry (DXA) before and after the 4-week period. Muscle strength and running velocity were measured with field tests. Results. As compared to placebo, the HICA supplementation increased significantly body weight (p < 0.005) and whole lean body mass (p < 0.05) while fat mass remained constant. The lean body mass of lower extremities increased by 400 g in HICA but decreased by 150 g in PLACEBO during the study. This difference between the groups was significant (p < 0.01). The HICA supplementation decreased the whole body DOMS symptoms in the 4th week of the treatment (p < 0.05) when compared to placebo. Muscle strength and running velocity did not differ between the groups. Conclusion. Already a 4-week HICA supplementation of 1.5 g a day leads to small increases in muscle mass during an intensive training period in soccer athletes.
Background. The TGFβ1-induced signal transduction processes involved in growth and differentiation are only partly known. The three-dimensional epithelial differentiation model, in which T84 epithelial cells are induced to differentiate either with TGFβ1 or IMR-90 mesenchymal cell-secreted soluble factors, is previously shown to model epithelial cell differentiation seen in intestine. That model has not been used for large scale gene expression studies, such as microarray method. Therefore the gene expression changes were studied in undifferentiated and differentiated three-dimensional T84 cultures with cDNA microarray method in order to study the molecular changes and find new players in epithelial cell differentiation. Results. The expression of 372 genes out of 5188 arrayed sequences was significantly altered, and 47 of them were altered by both mediators. The data were validated and the altered genes are presented in ontology classes. For the genes tested the expressions in protein level were in accordance with the mRNA results. We also found 194 genes with no known function to be potentially important in epithelial cell differentiation. The mRNA expression changes induced by TGFβ1 were bigger than changes induced by soluble factors secreted by IMR-90 mesenchymal cells. The gene expression data was depicted in already known signaling pathway routes. Conclusion. Our results reveal potential new signaling pathways and several new genes affected by TGFβ in epithelial cell differentiation. The differentiation induced by TGFβ1 appears to be more potent than the differentiation induced by mesenchymal cells. This study indicates that our cell culture model is a suitable tool in studying regulatory mechanisms during epithelial cell differentiation in intestine. Furthermore the present results indicate that our model is a good tool for finding new players acting in the differentiation of epithelial cells.
An optic fibre method was used to measure in humans in vivo Achilles (ATF) and patellar tendon forces (PTF) during submaximal squat jumps (SJ) and counter movement jumps (CMJ). Normal two-legged jumps on a force plate and one-legged jumps on a sledge apparatus were made by four volunteers. Kinetics, kinematics, and muscle activity from seven muscles were recorded. The loading patterns of the tendomuscular system differed among the jumping conditions, but were similar when the jumping height was varied. Peak PTF were greater than ATF in each condition. In contrast to earlier simulation studies it was observed that tendomuscular force could continue to increase during the shortening of muscle-tendon unit in CMJ. The concentric tendomuscular output was related to the force at the end of the stretching phase while the enhancement of the output in CMJ compared to SJ could not be explained by increases in muscle activity. The stretching phase in CMJ was characterised by little or no electromyogram activity. Therefore, the role of active stretch in creating beneficial conditions for the utilisation of elastic energy in muscle was only minor in these submaximal performances. The modelling, as used in the present study, showed, however, that tendon underwent a stretch-shortening cycle, thus having potential for elastic energy storage and utilisation. In general, the interaction between muscle and tendon components may be organised in a manner that takes advantage of the basic properties of muscle at given submaximal and variable activity levels of normal human locomotion.
Background. Diabetes has negative, and exercise training positive, effects on the skeletal muscle vasculature, but the mechanisms are not yet fully understood. In the present experiment the effects of running exercise on the mRNA expression of pro- and antiangiogenic factors were studied in healthy and diabetic skeletal muscle. The responses in capillaries and muscle fibers, collected from the muscle with laser capture microdissection, were also studied separately. Methods. Healthy and streptozotocin-induced diabetic mice were divided into sedentary and exercise groups. Exercise was a single bout of 1 h running on a treadmill. Gastrocnemius muscles were harvested 3 h and 6 h post exercise, and angiogenesis-related gene expressions were analyzed with real-time PCR. In addition to muscle homogenates, capillaries and muscle fibers were collected from the muscle with laser capture microdissection method and analyzed for vascular endothelial growth factor-A (VEGF-A) and thrombospondin-1 (TSP-1) mRNA expression. Results. Of the proangiogenic factors, VEGF-A and VEGF receptor-2 (VEGFR-2) mRNA expression increased significantly (P < 0.05) in healthy skeletal muscle 6 h post exercise. VEGF-B also showed a similar trend (P = 0.08). No significant change was observed post exercise in diabetic muscles in the expression of VEGF-A, VEGFR-2 or VEGF-B. The expression of angiogenesis inhibitor TSP-1 and angiogenic extracellular matrix protein Cyr61 were significantly increased in diabetic muscles (P < 0.05–0.01). Capillary mRNA expression resembled that in the muscle homogenates, however, the responses were greater in capillaries compared to muscle homogenates and pure muscle fibers. Conclusion. The present study is the first to report the effects of a single bout of exercise on the expression of pro- and antiangiogenic factors in diabetic skeletal muscle, and it provides novel data about the separate responses in capillaries and muscle fibers to exercise and diabetes. Diabetic mice seem to have lower angiogenic responses to exercise compared to healthy mice, and they show markedly increased expression of angiogenesis inhibitor TSP-1. Furthermore, exercise-induced VEGF-A expression was shown to be greater in capillaries than in muscle fibers.
Background. Acid–base balance refers to the equilibrium between acids and bases in the human body. Nutrition may affect acid–base balance and further physical performance. With the help of PRAL (potential renal acid load), a low-protein vegetarian diet (LPVD) was designed to enhance the production of bases in body. The aim of this study was to investigate if LPVD has an effect on blood acid–base status and performance during submaximal and maximal aerobic cycling. Methods. Nine healthy, recreationally active men (age 23.5 ± 3.4 yr) participated in the study and were randomly divided into two groups in a cross-over study design. Group 1 followed LPVD for 4 days and group 2 ate normally (ND) before performing a cycle ergometer test. The test included three 10-min stages at 40, 60 and 80% of VO2max. The fourth stage was performed at 100% of VO2max until exhaustion. After 10–16 days, the groups started a second 4-day diet, and at the end performed the similar ergometer test. Venous blood samples were collected at the beginning and at the end of both diet periods and after every stage cycled. Results. Diet caused no significant difference in venous blood pH, strong ion difference (SID), total concentration of weak acids (Atot), partial pressure of CO2 (pCO2) or HCO3- at rest or during cycling between LPVD and ND. In the LPVD group, at rest SID significantly increased over the diet period (38.6 ± 1.8 vs. 39.8 ± 0.9, p=0.009). Diet had no significant effect on exercise time to exhaustion, but VO2 was significantly higher at 40, 60 and 80% of VO2max after LPVD compared to ND (2.03 ± 0.25 vs. 1.82 ± 0.21 l/min, p=0.035; 2.86 ± 0.36 vs. 2.52 ± 0.33 l/min, p<0.001 and 4.03 ± 0.50 vs. 3.54 ± 0.58 l/min, p<0.001; respectively). Conclusion. There was no difference in venous blood acid–base status between a 4-day LPVD and ND. VO2 was increased during submaximal cycling after LPVD suggesting that the exercise economy was poorer. This had no further effect on maximal aerobic performance. More studies are needed to define how nutrition affects acid–base balance and performance.
BACKGROUND: The present study compares two different weight reduction regimens both with a moderately high protein intake on body composition, serum hormone concentration and strength performance in non-competitive female athletes. METHODS: Fifteen normal weighted women involved in recreational resistance training and aerobic training were recruited for the study (age 28.5 ± 6.3 yr, height 167.0 ± 7.0 cm, body mass 66.3 ± 4.2 kg, body mass index 23.8 ± 1.8, mean ± SD). They were randomized into two groups. The 1 KG group (n = 8; energy deficit 1100 kcal/day) was supervised to reduce body weight by 1 kg per week and the 0.5 KG group (n = 7; energy deficit 550 kcal/day) by 0.5 kg per week, respectively. In both groups protein intake was kept at least 1.4 g/kg body weight/day and the weight reduction lasted four weeks. At the beginning of the study the energy need was calculated using food and training diaries. The same measurements were done before and after the 4-week weight reduction period including total body composition (DXA), serum hormone concentrations, jumping ability and strength measurements RESULTS: During the 4-week weight reduction period there were no changes in lean body mass and bone mass, but total body mass, fat mass and fat percentage decreased significantly in both groups. The changes were greater in the 1 KG group than in the 0.5 KG group in total body mass (p < 0.001), fat mass (p < 0.001) and fat percentage (p < 0.01). Serum testosterone concentration decreased significantly from 1.8 ± 1.0 to 1.4 ± 0.9 nmol/l (p < 0.01) in 1 KG and the change was greater in 1 KG (30%, p < 0.001) than in 0.5 KG (3%). On the other hand, SHBG increased significantly in 1 KG from 63.4 ± 17.7 to 82.4 ± 33.0 nmol/l (p < 0.05) during the weight reducing regimen. After the 4-week period there were no changes in strength performance in 0.5 KG group, however in 1 KG maximal strength in bench press decreased (p < 0.05) while endurance strength in squat and counter movement jump improved (p < 0.05) CONCLUSION: It is concluded that a weight reduction by 0.5 kg per week with ~1.4 g protein/kg body weight/day can be recommended to normal weighted, physically active women instead of a larger (e.g. 1 kg per week) weight reduction because the latter may lead to a catabolic state. Vertical jumping performance is improved when fat mass and body weight decrease. Thus a moderate weight reduction prior to a major event could be considered beneficial for normal built athletes in jumping events.
Ensimmäinen vaihe väitöskirjatyötä on alan kirjallisuuteen tutustuminen. Helpoin tapa lähestyä aihetta on perehtyä tutkimusalueesta julkaistuihin kirjallisuus- katsauksiin. Meta-analyysit ovat systemaattisia kirjallisuuskatsauksia, joissa useiden alkuperäisjulkaisujen tulokset on yhdistetty kvantitatiivisin menetelmin. Vaikka meta-analyysien tulokset tulkitaan yleensä tieteellisesti valideiksi, piilee harhan mahdollisuus myös näissä julkaisuissa. Erityisesti nuoren tutkijan on hyvä tutustua meta-analyysien metodeihin ja oppia sen myötä tulosten kriittistä arviointia.
When released from an initial, static, forward lean angle and instructed to recover with a single step, some older adults are able to meet the task requirements, whereas others either stumble or fall. The purpose of the present study was to use the concept of margin of stability (MoS) to investigate balance recovery responses in the anterior-posterior direction exhibited by older single steppers, multiple steppers and those that are able to adapt from multiple to single steps following exposure to repeated forward loss of balance. One hundred and fifty-one healthy, community dwelling, older adults, aged 65–80 years, participated in the study. Participants performed four trials of the balance recovery task from each of three initial lean angles. Balance recovery responses in the anterior-posterior direction were quantified at three events; cable release (CR), toe-off (TO) and foot contact (FC), for trials performed at the intermediate lean angle. MoS was computed as the anteriorposterior distance between the forward boundary of the Base of Support (BoS) and the vertical projection of the velocity adjusted centre of mass position (XCoM). Approximately one-third of participants adapted from a multiple to a single step recovery strategy following repeated exposure to the task. MoS at FC for the single and multiple step trials in the adaptation group were intermediate between the exclusively single step group and the exclusively multiple step group, with the single step trials having a significant, 3.7 times higher MoS at FC than the multiple step trials. Consistent with differences between single and multiple steppers, adaptation from multiple to single steps was attributed to an increased BoS at FC, a reduced XCoM at FC and an increased rate of BoS displacement from TO to FC. Adaptations occurred within a single test session and suggest older adults that are close to the threshold of successful recovery can rapidly improve dynamic stability following repeated exposure to a forward loss of balance.
<b>Purpose</b><br> The present study examined the effects of repetitive hopping training on muscle activation profiles and fascicle–tendon interaction in the elderly. <br> <b>Methods</b><br> 20 physically active elderly men were randomly assigned for training (TG) and control groups (CG). TG performed supervised bilateral short contact hopping training with progressively increasing training volume. Measurements were performed before the training period (BEF) as well as after 2 weeks (2 W) and 11 weeks (11 W) of training. During measurements, the gastrocnemius medialis–muscle (GaM) fascicle and its outer Achilles tendon length changes during hopping were examined by ultrasonography together with electromyographic (EMG) activities of calf muscles, kinematics, and kinetics. <br> <b>Results</b><br> At 2 W, the ankle joint stiffness was increased by 21.0 ± 19.3 % and contact time decreased by 9.4 ± 7.8 % in TG. Thereafter, from 2–11 W the jumping height increased 56.2 ± 18.1 % in TG. Simultaneously, tendon forces increased 24.3 ± 19.0 % but tendon stiffness did not change. GaM fascicles shifted to shorter operating lengths after training without any changes in their length modifications during the contact phase of hopping. Normalized EMG amplitudes during hopping did not change with training. <br> <b>Conclusions</b><br> The present study shows that 11 W of hopping training improves the performance of physically active elderly men. This improvement is achieved with shorter GaM operating lengths and, therefore, increased fascicle stiffness and improved tendon utilization after training. Based on these results, hopping training could be recommended for healthy fit elderly to retain and improve rapid force production capacity.<br>
Flexor hallucis longus (FHL) muscle has several functions, including plantarflexion of the ankle, flexion of the big toe and support of the medial longitudinal arch. To date, only a few studies have used non-invasive methods to examine FHL behavior during real-life movements, although the proper functioning of this muscle may be important to increase sport performance, the altered FHL function may contribute to the susceptibility to Achilles tendinopathy and the function of FHL is altered in other clinical conditions such as flatfoot. FHL seems to be multifunctional but other active and passive structures also contribute to the same functions. Because of the multifunctionality of the foot structures and FHL itself, it is hard to define the main role of FHL during certain kinds of tasks and real-life movements. It is also more difficult to determine how morphological changes in the FHL affect its function. In this review we summarise studies that have examined FHL function focusing particularly on functionally relevant in vivo measurements, and possible effects of FHL anatomical and functional changes. Furthermore we make suggestions regarding studies that are needed in the future to fill the gaps in our knowledge about the role of FHL.
Introduction: The study aim was to construct a technical and tactical analysis of women’s volleyball based on notational analysis in top-level and junior women’s European volleyball matches, to compare these two levels, and to clarify the differences between the winners and losers of a set. Material and Methods: Four matches from the 2010 FIVB Women’s Volleyball World Championships and 2010 CEV Junior Women’s European Championship 2010 were analyzed using Data Volley software. The number and performance level of different skills were recorded in total and were grouped according to the role of the players. Methods of scoring and attacking zones were also analyzed. Results: There were only slight differences between the two levels in terms of success in different skills. When the skill executions were compared between the winning and losing teams of a set within the levels, less successful skill executions and more errors in different skills were found for the losing teams. Conclusions: The results seem to indicate that there are only minor differences between adult and junior women’s volleyball at the highest level. Attacking seems to be the most important skill concerning winning in both levels. The efficiency of attacking seems to depend upon the quality and versatility of the setting and also from the physical abilities of the players.
Human leg muscles are often activated inhomogeneously, e.g. in standing. This may also occur in complex tasks like walking. Thus, bipolar surface electromyography (sEMG) may not accurately represent whole muscle activity. This study used 64-electrode high-density sEMG (HD-sEMG) to examine spatial variability of lateral gastrocnemius (LG) muscle activity during the stance phase of walking, maximal voluntary contractions (MVCs) and maximal M-waves, and determined the effects of different normalization approaches on spatial and inter-participant variability. Plantar flexion MVC, maximal electrically elicited M-waves and walking at self-selected speed were recorded in eight healthy males aged 24–34. sEMG signals were assessed in four ways: unnormalized, and normalized to MVC, M-wave or peak sEMG during the stance phase of walking. During walking, LG activity varied spatially, and was largest in the distal and lateral regions. Spatial variability fluctuated throughout the stance phase. Normalizing walking EMG signals to the peak value during stance reduced spatial variability within LG on average by 70%, and inter-participant variability by 67%. Normalizing to MVC reduced spatial variability by 17% but increased inter-participant variability by 230%. Normalizing to M-wave produced the greatest spatial variability (45% greater than unnormalized EMG) and increased inter-participant variability by 70%. Unnormalized bipolar LG sEMG may provide misleading results about representative muscle activity in walking due to spatial variability. For the peak value and MVC approaches, different electrode locations likely have minor effects on normalized results, whereas electrode location should be carefully considered when normalizing walking sEMG data to maximal M-waves.
Modeling the force-velocity dependence of a muscle-tendon unit has been one of the most interesting objectives in the field of muscle mechanics. The so-called Hill’s equation [1,2] is widely used to describe the force-velocity relationship of muscle fibers. Hill’s equation was based on the laboratory measurements of muscle fibers and its application to the practical measurements in muscle mechanics has been problematic. Therefore, the purpose of this study was to develop a new explicit calculation method to determine the force-velocity relationship, and test its function in experimental measurements. The model was based on the motion analysis of arm movements. Experiments on forearm rotations and whole arm rotations were performed downwards and upwards at maximum velocity. According to the present theory the movement proceeds as follows: start of motion, movement proceeds at constant maximum rotational moment (Hy- pothesis 1), movement proceeds at constant maximum power (Hypothesis 2), and stopping of motion. Theoretically derived equation, in which the motion proceeds at constant maximum power, fitted well the experimentally measured results. The constant maximum rotational moment hypothesis did not seem to fit the measured results and therefore a new equation which would better fit the measured results is needed for this hypothesis.
Aims: The purpose of this paper was to continue the previous study of arm rotation movement where A.V. Hill’s force-velocity relationship was transformed into a constant maximum power model consisting of three different components of power. Methodology: In the present study a new model of Hill’s equation was applied for accelerated motions. This theoretically derived model of further development of Hill’s force-velocity relationship was tested by fitting it into two arm push measurements of shot put experiments. The results of the further development of Hill’s equation for accelerated motions were compared with the mechanics of the constant power model of the previous study. Results: The analyses of the present study verified that this theoretically derived equation for accelerated motions was in agreement with the measured data of shot put experiments. The fittings succeeded and they coincided with the velocity curves of the measured shot put experiments and the constant power model of the previous study. Conclusion: In the present study the progress of movement was concluded to be as follows: 1) the state of low speed, maximal acceleration which applies to the hypothesis of constant force, 2) the state of high speed, maximal power which applies to the hypothesis of constant power, where the constant power model of previous study and the present development of Hill’s equation for accelerated motion were acting. This is a new approach to Hill’s equation.
Large forces are generated under the big toe in the push-off phase of walking. The largest flexor muscle of the big toe is the flexor hallucis longus (FHL), which likely contributes substantially to these forces. This study examined FHL function at different levels of isometric plantarflexion torque and in the push-off phase at different speeds of walking. FHL and calf muscle activity were measured with surface EMG and plantar pressure was recorded with pressure insoles. FHL activity was compared to the activity of the calf muscles. Force and impulse values were calculated under the big toe, and were compared to the entire pressed area of the insole to determine the relative contribution of big toe flexion forces to the ground reaction force. FHL activity increased with increasing plantarflexion torque level (F=2.8, P=0.024) and with increasing walking speed (F=11.608, P<0.001). No differences were observed in the relative contribution of the force under the big toe to the entire sole between different plantarflexion torque levels (F=0.836, P=0.529). On the contrary, in the push-off phase of walking, peak force under the big toe increased at a higher rate than force under the other areas of the plantar surface (F=3.801, P=0.018), implying a greater relative contribution to total force at faster speeds. Moreover, substantial differences were found between isometric plantarflexion and walking concerning FHL activity relative to that of the calf muscles, highlighting the task-dependant behaviour of FHL.
Footwear, in one form or another, have been around for millennia. The advancements in the technology have made possible the transformation of animal skin and fur wrapped around feet by our ancestors into modern-day marvels of athletic shoes. Arguably one of the most pronounced innovations in the field of footwear design is the introduction of unstable shoe construction (USC), over the last few decades. Most widely investigated shoes are the Masai Barefoot Technology (MBT) shoes. Numerous scientific studies conducted on these shoes have revealed their effects on human gait and posture in healthy and morbid populations.
Purpose Hypertrophic resistance exercise (HRE) induces central and peripheral fatigue. However, more detailed information about changes in corticospinal excitability remains to be elucidated. Methods Eleven volunteers participated in the upper arm HRE which included one repetition maximum (1 RM) control contractions and three sets of 13 RM (SET1–3). Transcranial magnetic stimulation (TMS) was applied during maximal isometric voluntary contraction (MVC) at the end of each set and during control contractions to study changes in corticospinal excitability. Electrical stimulation was used in order to measure peripheral changes. Results MVC decreased after each set when compared to control contractions. Motor evoked potential (MEP) were 138.7 ± 52.7 % (p < 0.05), 130.4 ± 44.7 and 113.1 ± 31.4 % after SET1, SET2 and SET3, respectively, when compared to pre-exercise value. A significant reduction in MEP area between SET1 and SET3 (p < 0.05) was observed while silent period (SP) duration increased (~151–165 ms, p < 0.05) simultaneously between these sets. TMS-evoked twitch force during MVC increased significantly following each set when compared to pre-exercise value. Simultaneously, a significant reduction was observed in resting twitch force over the sets. Conclusions The results of this study clearly support the existence of both central and peripheral fatigue during HRE of elbow flexors. However, changes in the MEP area and SP suggest that during HRE of the elbow flexors, the corticospinal excitability increases first, until at some point, supraspinal fatigue takes over.
The present study investigated the effects of tendon curvature on measurements of tendon length using 3D-kinematic analysis. Curved and straight tendon models were employed for assessing medial gastrocnemius tendon length and strain during hopping (N = 8). Tendon curvature was identified using small reflective markers placed on the skin surface along the length of the tendon and a sum of vectors between the markers from the calcaneous up to the marker at the origin of tendon was calculated. The straight tendon was defined as a length of vector from the calcaneous to the marker at the origin of tendon. The curved tendon method yielded 5.0 ± 1.3 mm longer tendon (p < 0.001) than the straight tendon model. Tendon elongation was 2.1 ± 1.6 mm and peak strain 1.3 ± 0.7% smaller in curved than in straight tendon model (p < 0.01). The results suggest that the commonly used straight tendon model underestimate slightly but significantly the true tendon length but overestimate the strain and elongation.
Abstract. The aim of this study was to make use of a pr eviously introduced method of a simulated tripping perturbation to examine stability of walking in individuals with and with out cerebral palsy. This tripping perturbation is a forward-dynamics analys is, and it works so that in a subjec t-specific muscle-driven simulation of walking, created from experimental gait data, a force is applied to the swin g-foot, and resulting changes in the kinematics are observed. Here, changes in the fore-aft position of the trunk were analyzed. Subjects were 10 children with spastic diplegic cerebral palsy and eight un impaired children walking at their self-sel ected speed. Several tripping perturbations throughout the swing phase were performed, and each perturbation was used to analyze stability at a respective instant of time. At a given instant of time, walking was defined as stable if after initially deviating from its unpertur bed position, because of the pertur bation, the trunk then approached and stayed close to that position. Walking was in turn de fined as unstable if the trunk moved away from its unperturbed position. All unimpaired subjects were stable at some point of their swi ng phases, wherea s six out of the ten CP subjects were never stable. The unimpaired subjects we re statistically signific antly stable for a larger percentage of the swing phase t han the CP subjects (p < 0. 05). On the average, unimpaired subjects were stable for 8.5% of the swing phase while CP subjects were st able for 1.5% of the sw ing phase. These findings demonstrate that a tripping perturbation is capable of detecting a balance impa irment. Thus, it shows promise as a tool for rehabilitation.
Introduction: The short latency stretch reflex (SLR) is well described, but the stimulus that evokes the SLR remains elusive. One hypothesis states that reflex size is proportional to muscle fiber stretch, so this study examined the relationship between these 2 parameters in human triceps surae muscles. Methods: Achilles tendon taps and dorsiflexion stretches with different amplitudes and preactivation torques were applied to 6 participants while electromyography and muscle fascicle length changes were recorded in soleus and medial gastrocnemius (MG). Results: In response to tendon taps, neither fascicle length nor velocity changes were correlated with SLR size in either muscle, but accelerometer peaks were observed immediately after hammer-tendon contact. Similar results were obtained after dorsiflexion stretches. Discussion: Muscle fascicle stretch is poorly correlated with SLR size, regardless of perturbation parameters. We attribute the SLR trigger to the transmission of vibration through the lower limb, rather than muscle fiber stretch.
The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different subjects were performed downwards (elbow and shoulder extension) and upwards (elbow and shoulder flexion) with maximum velocity. These arm rotations were recorded with a special camera system and the theoretically derived model of constant maximum power was fitted to the experimentally measured data. The moment of inertia of the arm sectors was calculated using immersion technique for determining accurate values of friction coefficients of elbow and whole arm rotations. The experiments of the present study verified the conclusions of a previous study in which theoretically derived equation with constant maximum power was in agreement with experimentally measured results. The results of the present study were compared with the mechanics of Hill’s model and a further development of Hill’s force-velocity relationship was derived: Hill’s model was transformed into a constant maximum power model consisting of three different components of power. It was concluded that there are three different states of motion: 1) the state of low speed, maximal acceleration without external load which applies to the hypothesis of constant moment; 2) the state of high speed, maximal power without external load which applies to the hypothesis of constant power and 3) the state of maximal power with external load which applies to Hill’s equation. This is a new approach to Hill’s equation.
Introduction. Understanding the detailed control of human locomotion and balance can be improved, when individual motor units can be isolated and their firing rates followed in natural movement of large, fuctionally important muscles. For this reason the present study investigated the motor unit discharge rate (MUDR) in isometric and dynamic contractions of the soleus muscle. Methods: Eleven males performed isometric (10–100% MVC) and dynamic (10–40% MVC) plantar flexions. Intramuscular EMG was measured from Soleus with bipolar wire-electrodes and decomposed with custom built “Daisy” software. Results. The Soleus MUDR was significantly higher in concentric compared to isometric or eccentric contractions at all submaximal force levels (P<0.05). In isometric contractions MUDR increased up to 100% MVC. Conclusion: Motor unit discharge properties of a large plantarflexor can be measured in dynamic and maximal contractions. For a given torque output, MUDR is dependent upon contraction type, as set by the major mechanical differences between concentric and eccentric actions.
Aging is related to a variety of changes at the muscular level. It seems that the age-related changes in motor unit activation are muscle- and intensity dependent. The purpose of this study was to examine the motor unit discharge rate (MUDR) in both isometric and dynamic contractions of the aging soleus muscle. Eight elderly males participated in the study. The subjects performed isometric and dynamic plantar flexions while seated in an ankle dynamometer. The force levels studied were 10, 20, 40, 60, 80 and 100% of the isometric (ISO) maximal voluntary contractions (MVC) in ISO and 10, 20 and 40% in concentric (CON) and eccentric (ECC) contractions. Soleus intramuscular EMG was recorded with bipolar fine-wire electrodes and decomposed to individual trains of motor unit discharges. In ISO the MUDR increased with each force level from 40 to 100% MVC. In dynamic contractions the descriptive analysis showed a higher MUDR in CON compared to ISO or ECC. The difficulties of recording single motor units in dynamic contractions, especially in the elderly is discussed.
Reducing sitting time by means of sit–stand workstations is an emerging trend, but further evidence is needed regarding their health benefits. This cross-sectional study compared work time muscle activity patterns and spinal shrinkage between office workers (aged 24–62, 58.3% female) who used either a sit–stand workstation (Sit–Stand group, n = 10) or a traditional sit workstation (Sit group, n = 14) for at least the past three months. During one typical workday, muscle inactivity and activity from quadriceps and hamstrings were monitored using electromyography shorts, and spinal shrinkage was measured using stadiometry before and after the workday. Compared with the Sit group, the Sit–Stand group had less muscle inactivity time (66.2 ± 17.1% vs. 80.9 ± 6.4%, p = 0.014) and more light muscle activity time (26.1 ± 12.3% vs. 14.9 ± 6.3%, p = 0.019) with no significant difference in spinal shrinkage (5.62 ± 2.75 mm vs. 6.11 ± 2.44 mm). This study provides evidence that working with sit–stand workstations can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.
Overuse-induced injuries have been proposed as a predisposing factor for Achilles tendon (AT) ruptures. If tendons can be overloaded, their mechanical properties should change during exercise. Because there data are lacking on the effects of a single bout of long-lasting exercise on AT mechanical properties, the present study measured AT stiffness before and after a marathon. AT stiffness was determined as the slope of the force–elongation curve between 10 and 80% of maximum voluntary force. AT force–elongation characteristics were measured in an ankle dynamometer using simultaneous motion-capture-assisted ultrasonography. Oxygen consumption and ankle kinematics were also measured on a treadmill at the marathon pace. All measurements were performed before and after the marathon. AT stiffness did not change significantly from the pre-race value of 197±62Nmm–1 (mean ± s.d.) to the post-race value of 206±59Nmm–1 (N12, P0.312). Oxygen consumption increased after the race by 7±10% (P<0.05) and ankle kinematic data revealed that in nine out of 12 subjects, the marathon induced a change in their foot strike technique. The AT of the physically active individuals seems to be able to resist mechanical changes under physiological stress. We therefore suggest that natural loading, like in running, may not overstress the AT or predispose it to injury. In addition, decreased running economy, as well as altered foot strike technique, was probably attributable to muscle fatigue.
It has been postulated that human tendons are viscoelastic and their mechanical properties time-dependent. Although Achilles tendon (AT) mechanics are widely reported, there is no consensus about AT viscoelastic properties such as loading rate dependency or hysteresis, in vivo. AT force-elongation characteristics were determined from 14 subjects in an ankle dynamometer at different loading rates using motion capture assisted ultrasonography. AT stiffness and elongation were determined between 10 – 80% of maximum voluntary contraction (MVC) force at fast and slow loading rates. As subjects were unable to consistently match the target unloading rate in the slow condition, AT hysteresis was only calculated for the fast rate. There was a significant difference between the fast and the slow loading rates: 120 ± 6 vs. 21 ± 1% of MVC sˉ¹ (mean ± standard error), respectively. However, neither stiffness (193 ± 18 N mmˉ¹ vs. 207 ± 22 N mmˉ¹) nor elongation at any force level (13.0 ± 1.2 mm vs. 14.3 ± 0.9 mm at 80% of MVC) were significantly different between the fast and slow loading rates. Tendon hysteresis at the fast rate was 5 ± 2%. As stiffness was not sensitive to loading rate and hysteresis was small, it was concluded that elastic properties prevail over viscous properties in the human AT. The current results support the idea that AT stiffness is independent of loading rate.
The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anterior–posterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement reference systems that are currently used when skiing on snow. During sport-specific imitation jumps, differences in peak forces and impulses between the classic binding and the reference systems ranged from 8.0 to 19.9 % and were two to three times greater compared to differences between the skate binding and the reference systems (range −5.9 to 5.5 %). However, high similarity coefficients were observed with both bindings (classic binding 0.990–0.996, skate binding 0.996–0.999) compared to the reference systems. Based on these results, the skate binding was shown to be fully valid for use in field measurements of skate skiing, whereas some improvements have to be performed in the construction and sensor placements for the classic binding (vertical as well as anterior–posterior force component).
Nopeuskestävyysharjoittelua vaaditaan monissa urheilulajeissa. Erityisen keskeistä se on useissa yksilölajeissa, kuten juoksu, uinti ja pikaluistelu. Edelleen joukkuelajeissa kuten jääkiekossa ja jalkapallossa vaaditaan nopeuskestävyysharjoittelua, mutta lajien luonne on erilainen kuin yksilölajeissa. Yksilölajeissa kilpailusuoritus on yleensä yksi maksimaalinen suoritus, mutta esim. jääkiekossa ottelu kestää 60 minuuttia ja jäällä pelaaja on useita noin 40 sekunnin jaksoja. Siten nopeuskestävyyden luonne on erilainen. Tässä työssä on tarkoitus kuvata miten yksilölajissa (400 m:n juoksu) nopeuskestävyysharjoittelu johdetaan lajianalyysistä ja mitkä ovat nopeuskestävyysharjoittelun tutkimukselliset lähtökohdat. Lajianalyysi
Abstract: PCB 180 is a persistent non-dioxin-like polychlorinated biphenyl (NDL-PCB) abundantly present in food and the environment. Risk characterization of NDL-PCBs is confounded by the presence of highly potent dioxin-like impurities. We used ultrapure PCB 180 to characterize its toxicity profile in a 28-day repeat dose toxicity study in young adult rats extended to cover endocrine and behavioral effects. Using a loading dose/maintenance dose regimen, groups of 5 males and 5 females were given total doses of 0, 3, 10, 30, 100, 300, 1000 or 1700 mg PCB 180/kg body weight by gavage. Dose- responses were analyzed using benchmark dose modeling based on dose and adipose tissue PCB concentrations. Body weight gain was retarded at 1700 mg/kg during loading dosing, but recovered thereafter. The most sensitive endpoint of toxicity that was used for risk characterization was altered open field behavior in females; i.e. increased activity and distance moved in the inner zone of an open field suggesting altered emotional responses to unfamiliar environment and impaired behavioral inhibition. Other dose-dependent changes included decreased serum thyroid hormones with associated histopathological changes, altered tissue retinoid levels, decreased hematocrit and hemoglobin, decreased follicle stimulating hormone and luteinizing hormone levels in males and increased expression of DNA damage markers in liver of females. Dose-dependent hypertrophy of zona fasciculata cells was observed in adrenals suggesting activation of cortex. There were gender differences in sensitivity and toxicity profiles were partly different in males and females. PCB 180 adipose tissue concentrations were clearly above the general human population levels, but close to the levels in highly exposed populations. The results demonstrate a distinct toxicological profile of PCB 180 with lack of dioxin-like properties required for assignment of WHO toxic equivalency factor. However, PCB 180 shares several toxicological targets with dioxin-like compounds emphasizing the potential for interactions.
Background. This study examined the effect of simultaneous supplementation of extracellular buffer sodium bicarbonate (SB) and intracellular buffer beta-alanine (BA) on maximal sprint swimming. Methods. Thirteen competitive male swimmers completed 4 different treatments (placebo [PL], SB, BA + PL, and BA + SB) in a crossover procedure. PL or SB supplementation (0.3 g/kg body weight) was ingested 60 min before two maximal 100-m freestyle swims that were performed with a passive recovery of 12-min between each swim. Because of the known long washout period for carnosine, four weeks of BA supplementation (4.8 g per day) was started after the first week of PL or SB supplementation and performance testing. Results. The first maximal swims were similar, but the increase in time of the second versus the first 100-m swimming time was 1.5 s more (p < 0.05) in PL than in SB. Blood pH values were significantly (p < 0.05) greater in the SB and in the BA + SB groups compared to the PL and BA + PL values. There were no differences in peak blood lactate between the treatments. Conclusion. Supplementing with SB prior to performing maximal sprint swimming with repetitions under 60 s improves performance. However, co-supplementation with SB and BA did not confer any added benefit on maximal swim performance.
Study aim: The purpose of the present study was to investigate the impact of a social media exercise platform (HeiaHeia, Helsinki, Finland) on the level of physical activity, physical fitness, wellbeing and body weight of the service users. Material and methods: The subject group consisted of 2862 individuals who voluntarily participated in a web survey. Their age, gender, body mass index, physical fitness level and activity information were self-reported. Results: Most of the service users (78.1%) exercised more than three times a week. About 75% of the users reported that they were in good or excellent physical fitness, while about 50% were overweight. More than half (64.6%) of the service users reported that they had perceived an increase in their level of physical activity; and 46.4% of them reported that they had perceived an advance in their physical fitness after using the social media service. In addition, 54.0% of the users perceived an increase in their wellbeing. Every fifth (21.3%) user reported a decreased body weight after using the service. Those users with lower levels of physical fitness, lower physical activity and who were overweight were more likely to report that the use of the present service was beneficial. In total, about 75% of the service users reported at least one benefit after using the service. Conclusion: The present study demonstrated that the use of the social media exercise service can lead to an enhanced perceived level of physical activity, fitness and wellbeing. It also impacts positively on the users’ body weight. Thus, the present social media service can be recommended for use, especially for overweight, unfit and sedentary customers.
Objective To investigate the effects of a long-term, individualized and family-based lifestyle intervention on physical activity, sedentary behavior and diet quality in children. Methods We carried out a 2-year intervention study in a population sample of 506 children aged 6–8 years in Finland in 2007–2012. We allocated the participants at baseline in the intervention and control group. We assessed physical activity and sedentary behavior by questionnaires and diet by food records. Results Total physical activity (+ 9 min/d in intervention group vs. − 5 min/d in control group, p = 0.001 for time*group interaction), unsupervised physical activity (+ 7 min/d vs. − 9 min/d, p < 0.001) and organized sports (+ 8 min/d vs. + 3 min/d, p = 0.001) increased in the intervention group but not in the control group. Using computer and playing video games increased less in the intervention group than in the control group (+ 9 min/d vs. + 19 min/d, p = 0.003). Consumption of vegetables (+ 12 g/d vs. − 12 g/d, p = 0.001), high-fat vegetable-oil based margarine (+ 10 g/d vs. + 3 g/d, p < 0.001) and low-fat milk (+ 69 g/d vs. + 11 g/d, p = 0.042) and intake of dietary fiber (+ 1.3 g/d vs. + 0.2 g/d, p = 0.023), vitamin C (+ 4.5 mg/d vs. − 7.2 mg/d, p = 0.042) and vitamin E (+ 1.4 mg/d vs. + 0.5 mg/d, p = 0.002) increased in the intervention group but not in the control group. Consumption of butter-based spreads increased in the control group but not in the intervention group (+ 2 g/d vs. − 1 g/d, p = 0.002). Conclusions Individualized and family-based lifestyle intervention increased physical activity, attenuated increase in sedentary behavior and enhanced diet quality in children.
Introduction Diabetes Associated Protein in Insulin-sensitive Tissues (DAPIT) is a subunit of mitochondrial ATP synthase and has also been found to associate with the vacuolar H+-ATPase. Its expression is particularly high in cells with elevated aerobic metabolism and in epithelial cells that actively transport nutrients and ions. Deletion of DAPIT is known to induce loss of mitochondrial ATP synthase but the effects of its over-expression are obscure. Results In order to study the consequences of high expression of DAPIT, we constructed a transgenic cell line that constitutively expressed DAPIT in human embryonal kidney cells, HEK293T. Enhanced DAPIT expression decreased mtDNA content and mitochondrial mass, and saturated respiratory chain by decreasing H+-ATP synthase activity. DAPIT over-expression also increased mitochondrial membrane potential and superoxide level, and translocated the transcription factors hypoxia inducible factor 1α (Hif1α) and β-catenin to the nucleus. Accordingly, cells over-expressing DAPIT used more glucose and generated a larger amount of lactate compared to control cells. Interestingly, these changes were associated with an epithelial to mesenchymal (EMT)-like transition by changing E-cadherin to N-cadherin and up-regulating several key junction/adhesion proteins. At physiological level, DAPIT over-expression slowed down cell growth by G1 arrest and migration, and enhanced cell detachment. Several cancers also showed an increase in genomic copy number of Usmg5 (gene encoding DAPIT), thereby providing strong correlative evidence for DAPIT possibly having oncogenic function in cancers. Conclusions DAPIT over-expression thus appears to modulate mitochondrial functions and alter cellular regulations, promote anaerobic metabolism and induce EMT-like transition. We propose that DAPIT over-expression couples the changes in mitochondrial metabolism to physiological and pathophysiological regulations, and suggest it could play a critical role in H+-ATP synthase dysfunctions.
Istumisen terveyshaitat ovat puhuttaneet viime vuosina yhä enemmän. Yksi istumisen stereotypia on toimistotyöntekijä, joka joutuu istumaan toimistotuolissaan pitkät päivät. Työt on tehtävä, eikä perinteiselle työpisteelle ole järkevää vaihtoehtoa. Vai onko sittenkin? Säädettävä istuma-seisomatyöpiste on kerännyt viime vuosina ihastusta osakseen, koska se mahdollistaa istumajaksojen katkaisun työtehon kärsimättä. Tässä artikkelissa annan sinulle taustaa siihen, miksi pienikin istumisen tauottaminen kannattaa ja mikä on uusin tieto istuma-seisoma-työpisteiden hyödyllisyydestä. Onko toimistotyöntekijällä sittenkin toivoa?
Purpose: This study investigated effects of far-infrared sauna (FIRS) bathing on recovery from strength training and endurance training sessions, but also possible differences between FIRS and traditional (TRAD) Finnish sauna bathing. Methods: Ten healthy physically active male volunteers had on various days either a 60 min hypertrophic strength training session (STS) or a 34–40 min maximal endurance training session (ETS), which was following by 30 min bathing in special FIRS sauna at temperature of 35–50°C and humidity of 25–35%. After the sauna, subjects sat for 30 min at room temperature (21°C and 25–30% humidity). In comparison, 30 min of TRAD took place at 35–50°C and in 60–70% humidity. Performance tests included maximal isometric bench press and leg press, counter movement jump (CMJ) and maximal oxygen uptake on a treadmill. Results: After STS, there were decreases in maximal isometric bench press (p < 0.001), maximal isometric leg press (p < 0.001), CMJ (p < 0.001) and pH (p < 0.001), but increases in heart rate (p < 0.001) and lactate concentration (p < 0.001) as expected. During recovery there were no differences in any variables between FIRS and no sauna bathing (NO SAUNA). Maximal ETS increased oxygen uptake (p < 0.001), heart rate (p < 0.001), lactate concentration (p < 0.001) and decreased pH (p < 0.001) as expected. During recovery at 30 min, CMJ was significantly (p < 0.05) higher (0.34 ± 0.09 m) after FIRS bathing than after sitting with NO SAUNA (0.32 ± 0.0 m). After sauna heart rate was higher (p < 0.05) in TRAD (92 ± 13 beats/min) than in FIRS (71 ± 7 beats/min). Conclusion: In conclusion, deep penetration of infrared heat (approximately 3–4 cm into fat tissue and neuromuscular system) with mild temperature (35–50°C), and light humidity (25–35%) during FIRS bathing appears favorable for the neuromuscular system to recover from maximal endurance performance. FIRS bathing is a very light loading for the body and provides a comfortable and relaxing experience.
In some mammals, halogenated aromatic hydrocarbon (HAH) exposure causes wasting syndrome, defined as significant weight loss associated with lethal outcomes. The most potent HAH in causing wasting is 2,3,7,8-tetrachlorodibenzo-ρ-dioxin (TCDD), which exerts its toxic effects through the aryl hydrocarbon receptor (AHR). Since TCDD toxicity is thought to predominantly arise from dysregulation of AHR-transcribed genes, it was hypothesized that wasting syndrome is a result of to TCDD-induced dysregulation of genes involved in regulation of food-intake. As the hypothalamus is the central nervous systems' regulatory center for food-intake and energy balance. Therefore, mRNA abundances in hypothalamic tissue from two rat strains with widely differing sensitivities to TCDD-induced wasting syndrome: TCDD-sensitive Long–Evans rats and TCDD-resistant Han/Wistar rats, 23 h after exposure to TCDD (100 μg/kg) or corn oil vehicle. TCDD exposure caused minimal transcriptional dysregulation in the hypothalamus, with only 6 genes significantly altered in Long–Evans rats and 15 genes in Han/Wistar rats. Two of the most dysregulated genes were Cyp1a1 and Nqo1, which are induced by TCDD across a wide range of tissues and are considered sensitive markers of TCDD exposure. The minimal response of the hypothalamic transcriptome to a lethal dose of TCDD at an early time-point suggests that the hypothalamus is not the predominant site of initial events leading to hypophagia and associated wasting. TCDD may affect feeding behaviour via events upstream or downstream of the hypothalamus, and further work is required to evaluate this at the level of individual hypothalamic nuclei and subregions.
We report automated and time‐efficient (2 h per sample) profiling of muscle using ultra‐performance LC coupled directly with high‐definition MS (HDMSE). Soluble proteins extracted from rat gastrocnemius (n = 10) were digested with trypsin and analyzed in duplicate using a 90 min RPLC gradient. Protein identification and label‐free quantitation were performed from HDMSE spectra analyzed using Progenesis QI for Proteomics software. In total 1514 proteins were identified. Of these, 811 had at least three unique peptides and were subsequently used to assess the dynamic range and precision of LC‐HDMSE label‐free profiling. Proteins analyzed by LC‐HDMSE encompass the entire complement of glycolytic, β‐oxidation, and tricarboxylic acid enzymes. In addition, numerous components of the electron transport chain and protein kinases involved in skeletal muscle regulation were detected. The dynamic range of protein abundances spanned four orders of magnitude. The correlation between technical replicates of the ten biological samples was R2 = 0.9961 ± 0.0036 (95% CI = 0.9940 – 0.9992) and the technical CV averaged 7.3 ± 6.7% (95% CI = 6.87 – 7.79%). This represents the most sophisticated label‐free profiling of skeletal muscle to date.
Abstract Background Currently, there is insufficient evidence available regarding the relationship between level of physical fitness and health-related quality of life (HRQoL) in younger adults. Therefore, the aim of the present study was to investigate the impact of measured cardiovascular and musculoskeletal physical fitness level on HRQoL in Finnish young men. Methods In a cross-sectional study, we collected data regarding the physical fitness index, including aerobic endurance and muscle fitness, leisure-time physical activity (LTPA), body composition, health, and HRQoL (RAND 36) for 727 men [mean (SD) age 25 (5) years]. Associations between HRQoL and the explanatory parameters were analyzed using the logistic regression analysis model. Results Of the 727 participants who took part in the study, 45% were in the poor category of the physical fitness, while 37% and 18% were in the satisfactory and good fitness categories, respectively. A higher frequency of LTPA was associated with higher fitness (p < 0.001). Better HRQoL in terms of general health, physical functioning, mental health, and vitality were associated with better physical fitness. When the HRQoL of the study participants were compared with that of the age- and gender-weighted Finnish general population, both the good and satisfactory fitness groups had higher HRQoL in all areas other than bodily pain. In a regression analysis, higher LTPA was associated with three dimensions of HRQoL, higher physical fitness with two, and lower number of morbidities with all dimensions, while the effect of age was contradictory. Conclusions Our study of Finnish young men indicates that higher physical fitness and leisure-time physical activity level promotes certain dimensions of HRQoL, while morbidities impair them all. The results highlight the importance of health related physical fitness while promoting HRQoL.
Yliopisto-opetuksen ja oppimisen laatu voidaan käsittää hyvin monella eri tavalla. Tässä teoksessa laatua on käsitelty usealta eri näkökulmalta: esimerkiksi käsitteellis teoreettisen analyysin keinoin, korkeakoulupolitiikan viitekehyksestä ja suhteutta maila se pedagogiseen kohtaamiseen. Käsillä oleva teksti tuo uuden näkökulman laadun käsitteeseen: onko myös fyysinen ympäristö ja -tila osa yliopisto-opetuksen ja -oppimisen sekä tutkimustyön laatua? Tilaa ja ympäristöä ei yleensä mielletä laatutekijäksi. Mikä merkitys tilalla on kokemuksiimme, työssä viihtymiseen ja työn tuloksiin? Tässä artikkelissa keskityn ainoastaan joidenkin yliopistollisen tilan piirteiden pohtimiseen: ympäristön mykkyyteen, sen vaikutuksiin tunteisiimme, sekä siihen kuinka tilaa voidaan yksilöllisesti muokata ja sen avulla luoda sekä yksityisyyttä että yhteisyyttä.
Background: The TGFβ1-induced signal transduction processes involved in growth and differentiation are only partly known. The three-dimensional epithelial differentiation model, in which T84 epithelial cells are induced to differentiate either with TGFβ1 or IMR-90 mesenchymal cell-secreted soluble factors, is previously shown to model epithelial cell differentiation seen in intestine. That model has not been used for large scale gene expression studies, such as microarray method. Therefore the gene expression changes were studied in undifferentiated and differentiated three-dimensional T84 cultures with cDNA microarray method in order to study the molecular changes and find new players in epithelial cell differentiation. Results: The expression of 372 genes out of 5188 arrayed sequences was significantly altered, and 47 of them were altered by both mediators. The data were validated and the altered genes are presented in ontology classes. For the genes tested the expressions in protein level were in accordance with the mRNA results. We also found 194 genes with no known function to be potentially important in epithelial cell differentiation. The mRNA expression changes induced by TGFβ1 were bigger than changes induced by soluble factors secreted by IMR-90 mesenchymal cells. The gene expression data was depicted in already known signaling pathway routes. Conclusion: Our results reveal potential new signaling pathways and several new genes affected by TGFβ in epithelial cell differentiation. The differentiation induced by TGFβ1 appears to be more potent than the differentiation induced by mesenchymal cells. This study indicates that our cell culture model is a suitable tool in studying regulatory mechanisms during epithelial cell differentiation in intestine. Furthermore the present results indicate that our model is a good tool for finding new players acting in the differentiation of epithelial cells.
Cold exposure modulates the use of carbohydrates (CHOs) and fat during exercise. This phenomenon has mostly been observed in controlled cycling studies, but not during walking and running when core temperature and oxygen consumption are controlled, as both may alter energy metabolism. This study aimed at examining energy substrate availability and utilization during walking and running in the cold when core temperature and oxygen consumption are maintained. Ten lightly clothed male subjects walked or ran for 60-min, at 50% and 70% of maximal oxygen consumption, respectively, in a climatic chamber set at 0°C or 22°C. Thermal, cardiovascular, and oxidative responses were measured every 15-min during exercise. Blood samples for serum non-esterified fatty acids (NEFAs), glycerol, glucose, beta-hydroxybutyrate (BHB), plasma catecholamines, and serum lipids were collected immediately prior, and at 30- and 60-min of exercise. Skin temperature strongly decreased while core temperature did not change during cold trials. Heart rate (HR) was also lower in cold trials. A rise in fat utilization in the cold was seen through lower respiratory quotient (RQ) (−0.03 ± 0.02), greater fat oxidation (+0.14 ± 0.13 g · min ˉ¹) and contribution of fat to total energy expenditure (+1.62 ± 1.99 kcal · minˉ¹). No differences from cold exposure were observed in blood parameters. During submaximal walking and running, a greater reliance on derived fat sources occurs in the cold, despite the absence of concurrent alterations in NEFAs, glycerol, or catecholamine concentrations. This disparity may suggest a greater reliance on intra-muscular energy sources such as triglycerides during both walking and running.
Abstract. Cheung, Stephen S, Niina E. Mutanen, Heikki M. Karinen, Anne S. Koponen, Heikki Kyro ̈ la ̈ inen, Heikki O. Tikkanen, and Juha E. Peltonen. Ventilatory chemosensitivity, cerebral and muscle oxygenation, and total hemoglobin mass before and after a 72-day Mt. Everest expedition. High Alt Med Biol 15:331–340, 2014.— Background: We investigated the effects of chronic hypobaric hypoxic acclimatization, performed over the course of a 72-day self-supported Everest expedition, on ventilatory chemosensitivity, arterial saturation, and tissue oxygenation adaptation along with total hemoglobin mass (tHb-mass) in nine experienced climbers (age 37 – 6 years, _ VO 2peak 55 – 7mL $ kg - 1 $ min - 1 ). Methods: Exercise-hypoxia tolerance was tested using a constant treadmill exercise of 5.5 km $ h - 1 at 3.8% grade (mimicking exertion at altitude) with 3-min steps of progressive normobaric poikilocapnic hypoxia. Breath-by-breath ventilatory responses, Sp o 2 , and cerebral (frontal cortex) and active muscle (vastus lateralis) oxygenation were measured throughout. Acute hypoxic ventilatory response (AHVR) was determined by linear regression slope of ventilation vs. Sp o 2 . PRE and POST ( < 15 days) expedition, tHb-mass was measured using carbon monoxide-rebreathing. Results: Post-expedition, exercise-hypoxia tolerance improved (11:32 – 3:57 to 16:30 – 2:09 min, p < 0.01). AHVR was elevated (1.25 – 0.33 to 1.63 – 0.38 L $ min - 1. % - 1 Sp o 2 , p < 0.05). Sp o 2 decreased throughout exercise-hypoxia in both trials, but was preserved at higher values at 4800 m post-expedition. Cerebral oxygenation decreased progressively with increasing exercise-hypoxia in both trials, with a lower level of deoxyhemoglobin POST at 2400, 3500 and 4800 m. Muscle oxygenation also decreased throughout exercise- hypoxia, with similar patterns PRE and POST. No relationship was observed between the slope of AHVR and cerebral or muscle oxygenation either PRE or POST. Absolute tHb-mass response exhibited great individual variation with a nonsignificant 5.4% increasing trend post-expedition (975 – 154 g PRE and 1025 – 124 g POST, p = 0.17). Conclusions: We conclude that adaptation to chronic hypoxia during a climbing expedition to Mt. Everest will increase hypoxic tolerance, AHVR, and cerebral but not muscle oxygenation, as measured during simulated acute hypoxia at sea level. However, tHb-mass did not increase significantly and improvement in cerebral oxygenation was not associated with the change in AHVR
Global competition amongst cities has grown and branding has lately become an important part of cities’ strategies. The aim of this paper is to study the brand stakeholders’ perceptions of the sport city brand of a mid-sized city, Jyväskylä, in Finland. The authors conducted in-depth interviews with eleven city leaders and sport managers who had an infl uence on the sport brand of the city of Jyväskylä. The results show that in the minds of the respondents Jyväskylä has a strong image as a sport city. It stems from sports education, sports events, strong sports clubs, and active citizens. The results indicate that sports, and sporting events in particular, could be a key element in developing the brand image of the city of Jyväskylä. The results emphasize the importance of a closer cooperation and brand thinking amongst the stakeholders in order to develop the sport city brand of Jyväskylä. Zbog rastuće globalne konkurencije među gradovima brending je od nedavno postao važan element gradskih strategija. Rad prikazuje kako dionici marke doživljavaju sportsku marku Jyväskyläe, grada srednje veličine u Finskoj. Autori su proveli dubinske intervjue s jedanaest gradskih dužnosnika i sportskih menadžera koji su utjecali na sportsku marku grada Jyväskyläe. Prema rezultatima istraživanja, ispitanici smatraju kako Jyväskylä ima snažan imidž grada sporta. On počiva na sportskom obrazovanju, sportskim događanjima, jakim sportskim klubovima i aktivnom građanstvu. Rezultati pokazuju da bi sport, a posebno sportska događanja, mogli biti ključan element u razvoju imidža marke grada Jyväskyläe. Ističe se da je za razvoj marke grada sporta važna bliska suradnja i dobri, produktivni odnosi među dionicima.
AIM. Muscular fatigue is a complex phenomenon affected by muscle fiber type and several metabolic and ionic changes within myocytes. Mitochondria are the main determinants of muscle oxidative capacity which is also one determinant of muscle fatigability. By measuring the concentrations of intracellular stores of high-energy phosphates it is possible to estimate the energy production efficiency and metabolic recovery of the muscle. Low intrinsic aerobic capacity is known to be associated with reduced mitochondrial function. Whether low intrinsic aerobic capacity also results in slower metabolic recovery of skeletal muscle is not known. Here we studied the influence of intrinsic aerobic capacity on in vivo muscle metabolism during maximal, fatiguing electrical stimulation. METHODS. Animal subjects were genetically heterogeneous rats selectively bred to differ for non–trained treadmill running endurance, low capacity runners (LCRs) and high capacity runners (HCRs) (n = 15–19). We measured the concentrations of major phosphorus compounds and force parameters in a contracting triceps surae muscle complex using 31P-Magnetic resonance spectroscopy (31P-MRS) combined with muscle force measurement from repeated isometric twitches. RESULTS. Our results demonstrated that phosphocreatine re-synthesis after maximal muscle stimulation was significantly slower in LCRs (p<0.05). LCR rats also became promptly fatigued and maintained the intramuscular pH poorly compared to HCRs. Half relaxation time (HRT) of the triceps surae was significantly longer in LCRs throughout the stimulation protocol (p≤0.05) and maximal rate of torque development (MRTD) was significantly lower in LCRs compared to HCRs from 2 min 30 s onwards (p≤0.05). CONCLUSION. We observed that LCRs are more sensitive to fatigue and have slower metabolic recovery compared to HCRs after maximal muscle contractions. These new findings are associated with reduced running capacity and with previously found lower mitochondrial content, increased body mass and higher complex disease risk of LCRs.