Leg Extensor Research Articles

Relationships Between Muscle Quality, Maximal And Rapid Torque Characteristics, And Walking Speed In Elderly Females

The link between walking speed, rectus femoris (RF) muscle quality [echo intensity (EI)], and maximal and rapid strength in older adults is not well understood. PURPOSE: To examine the relationships between walking speed, RF EI, and maximal and rapid isometric torque characteristics of the leg extensors in elderly females. METHODS: Twenty elderly (67 ± 4 yrs.) females underwent one diagnostic ultrasound assessment followed by three isometric maximal voluntary contractions (MVC) of the leg extensors and a 6-min walk test. RF EI was measured on the right leg using a portable B-mode ultrasound imaging device and linear-array probe. Walking speed was determined as the average speed during the 6-min walk test. For each MVC, participants sat in an upright position and were instructed to push “as hard and fast as possible” against a load cell for 3-4 s. Isometric MVC peak torque (PT) was determined as the highest mean 500 ms epoch during the entire 3-4 s MVC plateau. Peak rate of torque development (RTD) was calculated during each MVC as the highest slope value for any 50 ms epoch that occurred over the initial 200 ms of the torque-time curve. Pearson correlation coefficients (r) were used to examine the relationships between walking speed, EI, PT, and RTD. A partial correlation was used to examine the relationship between walking speed and RTD when controlling for EI. RESULTS: There were significant relationships between walking speed and RTD (r = 0.451; P = 0.046) and EI (r = -0.497; P = 0.026). There was a significant negative relationship between EI and RTD (r = -0.469; P = 0.037). No relationships were observed between PT and walking speed (r = 0.394; P = 0.085) or EI (r = -0.413; P = 0.071). With EI as a control variable, there was no significant relationship between walking speed and RTD (r = 0.285; P = 0.238). CONCLUSIONS: We found a significant positive relationship between walking speed and RTD of the leg extensors in elderly females. Although the reason for this is uncertain, partial correlation analysis suggested that this relationship may be explained by the variance shared (collinearity) between walking speed and RF EI. From a functional standpoint, an age-related decrease in RTD due to its apparent collinearity with RF EI, may significantly impact the quality of life among older adults by impairing their walking speed performance abilities.

Different Effects of 2 mA and 4 mA Transcranial Direct Current Stimulation on Muscle Activity and Torque in a Maximal Isokinetic Fatigue Task.

Studies investigating the effects of transcranial direct current stimulation (tDCS) on fatigue and muscle activity have elicited measurable improvements using stimulation intensities ≤2 mA and submaximal effort tasks. The purpose of this study was to determine the effects of 2 mA and 4 mA anodal tDCS over the primary motor cortex (M1) on performance fatigability and electromyographic (EMG) activity of the leg muscles during a maximal isokinetic task in healthy young adults. A double-blind, randomized, sham-controlled crossover study design was applied. Twenty-seven active young adults completed four sessions, each spaced by 5–8 days. During session 1, dominance was verified with isokinetic strength testing, and subjects were familiarized with the fatigue task (FT). The FT protocol included 40 continuous maximum isokinetic contractions of the knee extensors and flexors (120°/s, concentric/concentric). During Sessions 2–4, tDCS was applied for 20 min with one of three randomly assigned intensities (sham, 2 mA or 4 mA) and the FT was repeated. The anode and cathode of the tDCS device were placed over C3 and the contralateral supraorbital area, respectively. A wireless EMG system collected muscle activity during the FT. The 2 mA tDCS condition had significantly less torque (65.9 ± 32.7 Nm) during the FT than both the sham (68.4 ± 33.9 Nm, p < 0.001) and 4 mA conditions (68.4 ± 33.9 Nm, p = 0.001). Furthermore, the 2 mA condition (33.8 ± 11.7%) had significantly less EMG activity during the FT than both the sham (39.7 ± 10.6%, p < 0.001) and 4 mA conditions (40.5 ± 13.4%, p = 0.001). Contrary to previous submaximal isometric fatigue investigations, the 2 mA tDCS condition significantly reduced torque production and EMG activity of the leg extensors during a maximal isokinetic FT compared with the sham and 4 mA conditions. Also, torque production and EMG activity in the 4 mA condition were not significantly different from sham. Thus, the effects of tDCS, and the underlying mechanisms, might not be the same for different tasks and warrants more investigation.

Muscle Power Predicts Bone Strength in Division II Athletes.

Yingling, VR, Webb, SL, Inouye, C, O, J, and Sherwood, JJ. Muscle power predicts bone strength in Division II athletes. J Strength Cond Res 34(6): 1657-1665, 2020-The relationship between muscle fitness measures and tibial bone strength in collegiate level athletes was investigated. Eighty-six Division II collegiate athletes (mean ± SD: age: [18-29 years], height: 1.71 m [0.09], mass: 66.7 kg [10.5], 56 female: 30 male) participated in this cross-sectional study. Maximum grip strength (GS), 1 repetition maximum leg press, and vertical jump peak power (PP) tests were measured. Cortical area, cortical bone mineral density (cBMD), moment of inertia, and bone strength (polar strength-strain index) were measured using peripheral quantitative computed tomography at 50% tibia length. For each bone strength parameter, a hierarchical multiple regression analysis was performed to examine the contribution of sex and the 3 muscle fitness parameters (muscle power, relative 1 repetition leg extensor strength, and relative GS) to bone parameters. Vertical jump PP explained 54-59% of the variance in bone strength parameters, and relative leg extensor and GS were not predictive of bone strength parameters. Muscle power correlated with bone mass and architecture variables but not cBMD values. Cortical bone mineral density was also not predicted by relative leg extensor strength or relative GS. Muscular fitness assessment, specifically PP calculated from vertical jump height assessments, provides a simple, objective, valid, and reliable measure to identify and monitor bone strength in collegiate athletes.

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial.

There are conflicting reports regarding the efficacy of plant versus animal-derived protein to support muscle and strength development with resistance training. The purpose of this study was to determine whether soy and whey protein supplements matched for leucine would comparably support strength increases and muscle growth following 12 weeks of resistance training. Sixty-one untrained young men (n = 19) and women (n = 42) (18–35 year) enrolled in this study, and 48 completed the trial (17 men, 31 women). All participants engaged in supervised resistance training 3×/week and consumed 19 grams of whey protein isolate or 26 grams of soy protein isolate, both containing 2 g (grams) of leucine. Multi-level modeling indicated that total body mass (0.68 kg; 95% CI: 0.08, 1.29 kg; p < 0.001), lean body mass (1.54 kg; 95% CI: 0.94, 2.15 kg; p < 0.001), and peak torque of leg extensors (40.27 Nm; 95% CI: 28.98, 51.57 Nm, p < 0.001) and flexors (20.44 Nm; 95% CI: 12.10, 28.79 Nm; p < 0.001) increased in both groups. Vastus lateralis muscle thickness tended to increase, but this did not reach statistical significance (0.12 cm; 95% CI: −0.01, 0.26 cm; p = 0.08). No differences between groups were observed (p > 0.05). These data indicate that increases in lean mass and strength in untrained participants are comparable when strength training and supplementing with soy or whey matched for leucine.

Intrarater Reliability and Agreement of Recommended Performance-Based Tests and Common Muscle Function Tests in Knee Osteoarthritis.

Some uncertainty persists regarding the reproducibility of the recommended core set of performance-based tests, as well as common muscle function tests, when applied in individuals with knee osteoarthritis (KOA). The purpose of this study was to investigate the intrarater reliability and agreement of the recommended core set of performance-based tests and common muscle function tests in KOA. Participants (N=40) with radiographic and/or symptomatic KOA were evaluated twice with a 3-day interval between test sessions using the following tests: Leg extensor (LE) maximal muscle power measured in a Nottingham Power Rig; knee extensor (KE) peak isometric strength measured with a handheld dynamometer; 40-m walk test; 30-second chair-stand test; and 9-step stair climb test. Reliability was assessed using a 2-way, mixed-effects, single-measures model (3,1), absolute agreement-type intraclass correlation coefficient (ICC). Agreement was assessed using 95% limits of agreement (LOA) and LOA relative to the mean score from test and retest (LOA-%). Reliability for all tests was very high (ICC ≥ 0.97). LOA (LOA-%) was ±32.3 watt (W) (±22%) for LE power; ±22.7 N·m (±24%) for KE strength; ±0.2 m/s (±10%) for 40-m walk test; ±2.4 repetitions (±14%) for 30-second chair-stand test; and ±2 second (±20%) for stair climb test. A potential participant learning effect was found for all 3 performance-based tests, indicated by the significantly better scores at retest. The very high reliability found for the performance-based tests supports findings from previous studies and confirms discriminate reliability of these tests on a group level. Also, very high reliability estimates were demonstrated for both muscle function tests. This study also provided estimates of agreement for both performance-based and muscle function tests, which are important to consider when using these tests on an individual level in clinical practice. When using these tests to monitor changes over time in the clinic, depending on the test, improvements of less than 10% to 24% could be a result of measurement error alone and therefore may not be considered an actual improvement after treatment.

The influence of prolonged strength training upon muscle and fat in healthy and chronically diseased older adults.

Physical muscle function and brain hippocampus size declines with age, accelerating after the age of 60. Strength training over a few months improves physical function, but less is known about how long-term strength training affects physical function and hippocampus volume. Therefore, we aimed to investigate the effect of 1-year strength training of two different intensities upon muscle mass, function, and hippocampus volume in retirement-age individuals. In this multidisciplinary randomized controlled trial (clinicaltrials.gov: NCT02123641), participants were allocated to either a) supervised, heavy resistance training (HRT, n=149, 3/wk), b) moderate intensity resistance training (MIT, n=154, 3/wk) or c) non-exercise activities (CON, n=148). 451 participants were randomized (62-70yrs., women 61%, ≈80% with a chronic medical disease) and 419 were included in the intention-to-treat analysis (n=143, 144 and 132; HRT, MIT and CON). Changes in muscle power (primary outcome), strength and size, physical function, body composition, hippocampus volume and physical/mental well-being were analyzed. Of the participants (HRT+MIT), 83% completed training at least 2/week. Leg extensor power was unchanged in all groups, but strength training had a positive effect on isometric knee extensor strength in both groups, whereas an increased muscle mass, cross-sectional area of vastus lateralis muscle, a decreased whole-body fat percentage, visceral fat content and an improved mental health (SF-36) occurred in HRT only. Further, chair-stand performance improved in all groups, whereas hippocampus volume decreased in all groups over time with no influence of strength training. Together, the results indicate that leg extensor power did not respond to long-term supervised strength training, but this type of training in a mixed group of healthy and chronically diseased elderly individuals can be implemented with good compliance and induces consistent changes in physiological parameters of muscle strength, muscle mass and abdominal fat.

Large Hypertrophy but Unmodified Specific Tension of Single Fibers of Body Builders

IntroductionMuscle hypertrophy is the main outcome of training for body building. Previous studies showed a discrepancy between the functional (force/tension) and structural (cross‐sectional area, CSA) proprieties of leg extensor muscles measured in vivo and the corresponding parameters measured in single muscle fibers [1] [2]. In particular, a puzzling finding from these studies was that of a lower specific tension of skinned fibers of body builders (BB) compared to a control (C) population.In this study we aimed to investigate the possible reasons behind the alleged lower specific tension in single fibers of a strictly diet‐and‐training‐controlled BB population.MethodsFive male body builders (26±4.7 yr; 87.2±9.7 kg; 178.4±7.5 cm) with a training history of at least 5 years were recruited for this study. Five age‐matched recreationally active males (24.6±3.6 yr; 84.4±14.9 kg; 186.4±4.4 cm) were recruited as controls. After ethical approval, biopsies from the vastus lateralis (VL) muscle were collected together with in‐vivo quadriceps maximum isometric voluntary contraction (MVC) and architecture and CSA. Data analysis included (i) single skinned fiber mechanics (n=200 fibers; maximum force, CSA, specific tension and calcium diffusion), (ii) single fiber myosin quantification (n=100 fibers), (iii) slow and fast fiber CSA via histological section analysis. In addition, swelling ratio (skinned fibers CSA/histological CSA) was calculated for each fiber type and for each subject. A general linear mixed model was used to assess statistically significant differences.ResultsQuadriceps MVC and CSA were 64% and 33% higher in BB than C (p&lt;0.05), VL pennation angle (PA) and thickness (MT) were 16% and 15% higher in BB than C (p&lt;0.05). Quadriceps specific force was 25% higher in BB than C (n.s.). Single skinned type 2 CSA and force were 48% and 28% higher in BB than C (p&lt;0.05), while specific tension was 19% lower (p&lt;0.05). Type 1 fibers specific tension was 32% higher in BB than C (p&lt;0.05). Myosin content and calcium diffusion were similar among populations. CSA determined in histological sections was 10% and 27% higher in BB than C (p&lt;0.05) for type1 and 2 fibers, respectively. When type 1 and type 2 fiber tensions were corrected for individual swelling ratio, the difference between BB and C disappeared.ConclusionsAlthough at first sight these findings seem to confirm that in type 2 skinned fibers of BB specific tension is lower than in C, once accounting for fiber swelling, this difference disappears. This is further confirmed by the lack of difference in myosin concentration and calcium diffusion kinetics.In contrast, the results point to the existence of a differential swelling response to the skinning process by BB and C fibers, possibly due to adaptations of the fiber cytoskeleton proteins or specific permeability of the membrane of slow and fast fibers.

A Comparison of Bone-Targeted Exercise Strategies to Reduce Fracture Risk in Middle-Aged and Older Men with Osteopenia and Osteoporosis: LIFTMOR-M Semi-Randomized Controlled Trial.

The Lifting Intervention For Training Muscle and Osteoporosis Rehabilitation for Men (LIFTMOR-M) trial examined efficacy and safety of two novel exercise programs in older men with low BMD. Men with low hip and/or LS BMD were randomized to high-intensity progressive resistance and impact training (HiRIT) or machine-based isometric axial compression (IAC) and compared to a nonrandomized matched control (CON). Outcomes included: hip and LS BMD; calcaneal ultrasound parameters; anthropometry; body composition; function (timed up-and-go [TUG], five-times sit-to-stand [FTSTS]); back extensor strength (BES); leg extensor strength (LES); compliance and adverse events. Ninety-three men (67.1 ± 7.5 years; 82.1 ± 11.6 kg; 175.2 ± 6.7 cm; FN T-score -1.6 ± 0.6) were randomized to HiRIT (n = 34) or IAC (n = 33), or allocated to CON (n = 26). HiRIT improved trochanteric BMD (2.8 ± 0.8%; -0.1 ± 0.9%, p = .024), LS BMD (4.1 ± 0.7%; 0.9 ± 0.8%, p = .003), BUA (2.2 ± 0.7%; -0.8 ± 0.9%, p = .009), stiffness index (1.6 ± 0.9%; -2.0 ± 1.1%, p = .011), lean mass (1.5 ± 0.8%; -2.4 ± 0.9%, p = .002), TUG, FTSTS, BES, and LES (p < .05) compared with CON. IAC improved lean mass (0.8 ± 0.8%; -2.4 ± 0.9%, p = .013) and FTSTS (-4.5 ± 1.6%; 7.5 ± 2.0%, p < .001) compared with CON. HiRIT improved LS BMD (4.1 ± 0.7%; 2.0 ± 0.7%, p = .039), stiffness index (1.6 ± 0.9%; -1.3 ± 0.9%, p = .025), and FTSTS (-10.7 ± 1.6%; -4.5 ± 1.7%, p = .010) compared with IAC. Exercise compliance was high (HiRIT 77.8 ± 16.6%; IAC 78.5 ± 14.8%, p = .872). There were five minor adverse events (HiRIT, 2; IAC, 3). HiRIT was well-tolerated and improved bone, function and fracture risk more than CON or IAC. © 2020 American Society for Bone and Mineral Research.

Free-leg side elevation of pelvis in single-leg jump is a substantial advantage over double-leg jump for jumping height generation

In single-leg jumps, humans achieve more than half the jumping height that they can reach for double-leg jumps. Although this bilateral deficit in jumping has been believed to be due to the reduction of leg extensor force/work exertions, we hypothesised that the three-dimensional biomechanical differences between double-leg and single-leg jumps also influence the bilateral deficit in jumping. Here, we show the substantial effect of the elevation of the pelvic free-leg side in single-leg squat jumps on the bilateral deficit in jumping in addition to extensor force reduction. We collected the kinematic and ground reaction force data during single-leg and double-leg squat jumps from ten male participants using motion capture systems and force platforms. We determined the components of the mechanical energy directly contributing to the height of the centre of mass due to segment movement. The energy due to rotations of the foot, shank, thigh, and pelvis were significantly greater in single-leg squat jumps than in double-leg squat jumps. The magnitudes of the difference in energy between single-leg and double-leg squat jumps due to the pelvis (0.54 ± 0.22 J/kg) was significantly larger than that due to any other segment (<0.30 J/kg). This indicates that pelvic elevation in single-leg jump is a critical factor causing bilateral deficit in jumping, and that humans generate the jumping height with a single leg not just by an explosive leg-extension but also by synchronous free-leg side elevation of the pelvis. The findings suggest that this pelvic mechanism is a factor characterising human single-leg jumps.

Three-dimensional kinetic function of the lumbo-pelvic-hip complex during block start.

Previous studies on joint kinetics during track and field block starts have been limited to lower-limb sagittal kinetics; however, we hypothesised that lumbopelvic extensors, lateral flexors, and hip abductors also act as substantial energy generators. The present study aimed to examine the three-dimensional lumbo-pelvic-hip kinetics to better understand the generation of mechanical energy during a block start. 3D kinematic and force data during block starts of 10 m maximal sprinting in 12 male sprinters (personal best in a 100 m sprint, 10.78 ± 0.19 s [range, 10.43-11.01 s]) were captured using a motion capture system and force platform. The three-dimensional lumbo-pelvic-hip kinetics were calculated. The peak lumbosacral extension torque (3.64 ± 0.39 Nm/kg) was significantly larger than any other lower-limb and lumbosacral torques (<3.0 Nm/kg). It was suggested that large lumbopelvic extension torques are needed during the block start to anchor the pelvis by cancelling out both hip extension torques acting on the pelvis, leading to hip extensor-induced thigh sagittal rotations rather than pelvic posterior tilt. During the double-stance phase, the lumbosacral extensors generated mechanical energy (0.35 ± 0.16 J/kg, 14 ± 4% of the sum of lumbosacral and lower-limb net joint work). During the single-stance phase, the sum of the net mechanical work by lumbosacral lateral flexors and front hip abductors was 0.35 ± 0.14 J/kg, which comprised 9 ± 3% of the sum of the net joint work. The results lead to the speculation of the importance of strengthening not only the leg extensors, but also the lumbopelvic extensors, lateral flexors, and hip abductors for block starts. Further training studies to verify this speculation will improve training strategies for the track and field block start performance.

Effect of eldecalcitol on muscle function and fall prevention in Japanese postmenopausal women: A randomized controlled trial

BackgroudExercises and vitamin D interventions have shown to improve muscle function and balance, and prevent falls in postmenopausal healthy women and in patients with osteoporosis. However, the effects of eldecalcitol on these factors remain undetermined. The present open-label, randomized, controlled study aimed to investigate the effects of eldecalcitol treatment in reducing falls in postmenopausal women, and improving muscle function and balance. MethodsThe study population included 226 Japanese postmenopausal women with osteoporosis. Patients were randomly divided into two groups on the basis of treatment with or without eldecalcitol (0.75 μg/day). Treatment continued for 6 months. Participants in both groups were instructed to perform back extensor muscle exercise. Isometric back extensor and leg extensor strength, grip power, ten-meter walking speed, timed up and go test and time of single leg standing were measured at baseline and 24 weeks. Patients were asked to record the number of falls during the 24-week period. ResultsThe percentage increase in average bilateral quadriceps muscle strength was significantly higher in the eldecalcitol group compared with the non-eldecalcitol group (right, p = 0.041; left, p = 0.042). In contrast, there were no significant differences in the strength of back muscles and grip power and the parameters of balance and walking abilities between the groups. There was no significant difference in the number of falls between the groups. ConclusionsA 24-week intervention of eldecalcitol improves the strength of the quadriceps muscles in postmenopausal women with osteoporosis. However, eldecalcitol neither improve balance and walking abilities nor reduce the number of falls.

Skeletal Muscle Myofibrillar Protein Abundance Is Higher in Resistance-Trained Men, and Aging in the Absence of Training May Have an Opposite Effect.

Resistance training generally increases skeletal muscle hypertrophy, whereas aging is associated with a loss in muscle mass. Interestingly, select studies suggest that aging, as well as resistance training, may lead to a reduction in the abundance of skeletal muscle myofibrillar (or contractile) protein (per mg tissue). Proteomic interrogations have also demonstrated that aging, as well as weeks to months of resistance training, lead to appreciable alterations in the muscle proteome. Given this evidence, the purpose of this small pilot study was to examine total myofibrillar as well as total sarcoplasmic protein concentrations (per mg wet muscle) from the vastus lateralis muscle of males who were younger and resistance-trained (denoted as YT, n = 6, 25 ± 4 years old, 10 ± 3 self-reported years of training), younger and untrained (denoted as YU, n = 6, 21 ± 1 years old), and older and untrained (denoted as OU, n = 6, 62 ± 8 years old). The relative abundances of actin and myosin heavy chain (per mg tissue) were also examined using SDS-PAGE and Coomassie staining, and shotgun proteomics was used to interrogate the abundances of individual sarcoplasmic and myofibrillar proteins between cohorts. Whole-body fat-free mass (YT > YU = OU), VL thickness (YT > YU = OU), and leg extensor peak torque (YT > YU = OU) differed between groups (p < 0.05). Total myofibrillar protein concentrations were greater in YT versus OU (p = 0.005), but were not different between YT versus YU (p = 0.325). The abundances of actin and myosin heavy chain were greater in YT versus YU (p < 0.05) and OU (p < 0.001). Total sarcoplasmic protein concentrations were not different between groups. While proteomics indicated that marginal differences existed for individual myofibrillar and sarcoplasmic proteins between YT versus other groups, age-related differences were more prominent for myofibrillar proteins (YT = YU > OU, p < 0.05: 7 proteins; OU > YT = YU, p < 0.05: 11 proteins) and sarcoplasmic proteins (YT = YU > OU, p < 0.05: 8 proteins; OU > YT&YU, p < 0.05: 29 proteins). In summary, our data suggest that modest (~9%) myofibrillar protein packing (on a per mg muscle basis) was evident in the YT group. This study also provides further evidence to suggest that notable skeletal muscle proteome differences exist between younger and older humans. However, given that our n-sizes are low, these results only provide a preliminary phenotyping of the reported protein and proteomic variables.

A study of age differences in whole-body reaction time and its relationship to leg extensor muscle strength in preschool children

A study of age differences in whole-body reaction time and its relationship to leg extensor muscle strength in preschool children

Correlation between leg extensor torque and the degree of sway.

[Purpose] The purpose of this study was to examine the correlation between leg extensor torque and the degree of sway. [Participants and Methods] We recruited 31 male and 22 female healthy adults. Strength Ergo 240 was used to measure leg extensor torque. A body pressure measurement system was used to measure the degree of sway. After the measurement, the correlation between these factors was investigated according to sex. [Results] In the males, a significant negative correlation was observed between leg extensor torque and the degree of sway. [Conclusion] In cases where therapists actively performed muscle strengthening and standing-up exercises to reduce the degree of sway in the males, the possibility that such efforts could increase leg extensor torque was observed.

Physical, physiological and psychological profiles of elite Turkish taekwondo athletes

Summary Study aim: To identify the physical, physiological and psychological profiles of elite Turkish taekwondo athletes. Material and methods: Twelve players of the Turkish national taekwondo team (age = 22.7 ± 2.8 years, BMI = 22.2 ± 1.4 kg/m2, body fat = 12.8 ± 3.4%) participated in the study. Anthropometric measurements including leg length and foot size were assessed. Maximal oxygen uptake, explosive power of leg extensors, isokinetic peak torque, muscular endurance, anaerobic power, agility, flexibility, maximal speed, reaction time, and postural balance were examined by incremental treadmill running, vertical jump, isokinetic strength, sit-ups and push-ups, Wingate, shuttle run, sit-and-reach, 30-meter sprint, multiple-choice reaction time, and General Postural Stability and Athlete Single Leg stability tests, respectively. Psychological characteristics including mental skills and mood states were evaluated using OMSAT-3 and POMS tests. Results: VO2max, isokinetic peak torque and Wingate test mean power values were 54.1 ± 4.4 mL ∙ kg−1 ∙ min−1, 191.7 ± 19.2 N ∙ m, and 9 ± 0.7 W/kg, respectively. Postural stability index 0.18 ± 0.06, single leg stability index 0.82 ± 0.11, reaction time 0.344 ± 0.032 s, 10 × 5-m shuttle run 17.09 ± 0.68 s, 30-meter sprint 4.60 ± 0.23 s, and vertical jump 43.5 ± 6.1 cm were the other values reported. The highest scores for the 12 mental skills in OMSAT-3 were for goal setting (6.25 ± 0.45) and self-confidence (6.16 ± 0.45). The lowest score was for Imagery (5.64 ± 0.36). The results of six mood states of POMS showed higher scores on the Vigor-activity, Anger-Hostility and Tension-Anxiety scales and lower scores on Depression-Dejection, Fatigue-Inertia and Confusion-Bewilderment than norms. Conclusions: The findings of this study revealed the physical, physiological, and psychological characteristics in taekwondo. The results of the tests could be useful for performance assessment of taekwondo players.

Correlation between ankle plantar flexor strength and leg extensor torque.

[Purpose] The purpose of this study is to consider the correlation between ankle plantar flexor strength and leg extensor torque in order to investigate whether the leg extension torque can be expected to increase as the triceps surae muscle strength is increased. [Participants and Methods] Healthy adults of 30 males and 22 females were recruited. Hand Held Dynamometer was used to measure ankle plantar flexor strength. Strength Ergo 240 was used to measure leg extensor torque. After measurement, a correlation between these factors was investigated by gender. [Results] For both males and females, a significant positive correlation between the left and right ankle plantar flexor strength and leg extensor torque was observed. [Conclusion] Actively performing muscle strengthening exercises for ankle plantar flexor by physical therapists was found to be meaningful in increasing leg extensor torque.

The Efects of Kinetotherapy in the Recovery of Patients with Gonartrosis

Gonarthrosis is one of the most frequent forms of degenerative rheumatism, characterized bybenign evolution andprognosis. Itequally interests both sexes, manifesting itself around the age of 40, and affecting mostly the elderly population. The disease appears as a consequence of the wearingaway of the epiphyseal cartilages, which lose their elasticity and resistance due to mechanical shocks during walking.The localization of the osteoarthritic process at the knee level is considered to be the most common, and, according toits gender based incidence pool, women are by far the most affected, especially after entering menopause. The degenerative osteoarthritic process of the knee is the result of an imbalance between the resistance of the joint structures and the stressorsthey are subjected to.In contrast to hiposteoarthritis, knee osteoarthritis could transform intoa dysfunctional disease early on, due to pain and impaired muscular strength, especially of the leg extensors. It is true, however, that severe degenerative, dysfunctional forms can be found almost exclusively in secondary gonarthrosis, caused by misalignments (genuvarum, valgum, etc.), meniscopathies, ligamentous instability, traumas interesting intra-articular bone insertion, chronic nonspecific or specific inflammatory articular processes, endocrine-metabolic disorders.Starting from these assumptions and taking into account the number of people searching treatment for this condition, we believed that thorough theoretical and practical research was needed regarding the efficiency of kinetotherapyin slowing down the evolutionary process of the disease.

Comparison of age-specific leg extensor muscle function torque-time and rapid velocity attributes across the adult lifespan: A relative deficiency investigation.

The purposes of this study were to examine the age-related differences in absolute and normalized torque-time parameters in five distinct groups across the adult lifespan, and the relationship between rapid strength and limb acceleration capacities across the lifespan. One-hundred and thirty-six healthy men were categorized as young athletes (n=27; age=20.7yrs), young controls (n=32; 21.9yrs), middle young (n=32; 49.8yrs), middle old (n=15; 58.9yrs), and old (n=30; 71.3yrs) cohorts. Participants performed maximal voluntary contractions (MVCs) of the leg extensors under isometric and isokinetic (240deg.·s-1) conditions. Outcome measures included peak torque (PT), absolute and MVC normalized (norm) rate of torque development (RTD) at 50 and 200ms, RTD50/PT ratio, and rate of velocity development (RVD). The PT and absolute RTD at 200ms declined from young to old age (P<.05). The middle age groups exhibited an overall preservation of early RTD, and a potential enhancement of early normalized RTD (P=.06 for middle young vs. controls, for RTDnorm50). The RTD50/PT ratio was higher in the middle young (P<.05) compared to both the young groups. Generally, the RVD declined more linearly and exhibited worse preservation at mid-life than the early absolute or normalized RTD variables. All absolute torque-time variables were correlated (r=0.43-0.73, P<.001) to the RVD for all groups combined. These findings showed distinct age-related declines occurred for different muscle function parameters unique to specific stages of the lifespan. Normalized RTD variables may reveal plausible mechanisms of age-related neuromuscular changes and the RTD50/PT ratio may be a useful tool for determining relative deficiencies, such that mid-life adults (45-64yrs) should address their relative limitation of PT by enhancing strength at mid-life, whereas older adults (65+ yrs) may need more emphasis on RTD improvements. In addition, both mid-life and older men should seek to improve rapid limb velocity capacities due to the susceptibility of RVD to decline more incrementally across the lifespan. Such information may help to improve anti-aging strategies by countering age-specific muscle function deficiencies and may improve mid-life adults' ability to transition better functionally into old age.

The Influence of Prolonged Strength Training Upon Muscle and Fat in Healthy and Chronically Diseased Elderly Close to Retirement Age

Background: Physical and cognitive function declines with age, accelerating after the age of 60. Strength training over a few months improves physical function, but less is known about how long-term strength training affects physical and cognitive function. Therefore, we aimed to investigate the effect of 1 year strength training of two different intensities upon muscle mass, function, and cognition in retirement-age individuals. Methods: In this randomized controlled trial (clinicaltrials.gov: NCT02123641), participants were allocated to either a) supervised, heavy resistance training (HRT, n=149, 3/wk), b) moderate intensity resistance training (MIT, n=154, 3/wk) or c) non-exercise activities (CON, n=148). 451 participants were randomized (62-70 yrs, women 61%, ≈80% with a chronic medical disease) and 419 were included in the intention-to-treat analysis (n=143, 144 and 132; HRT, MIT and CON). Changes in muscle power (primary outcome), strength and size, physical function, body composition, hippocampus volume and physical/mental well-being were analysed. Findings: Of the participants (HRT+MIT), 83% completed training at least 2/wk. Leg extensor power was unchanged in all groups, but strength training had positive effects on isometric knee extensor strength and muscle mass, whereas an increased cross-sectional area of vastus lateralis muscle, a decreased whole-body fat percentage and visceral fat content occurred in HRT only. Further, chair-stand performance and 400 m walking time improved in all groups. Hippocampus volume decreased in all groups over time with no influence of strength training, whereas mental health (SF-36) improved more in HRT than MIT. Interpretation:Together, the results indicate that long-term supervised strength training in both healthy and chronically diseased elderly individuals can be implemented with good compliance and induces consistent changes in physiological parameters of muscle and fat. Trial Registration: Clinicaltrials.gov (NCT02123641). Funding Statement: Nordea Foundation (Centre for Healthy Ageing grant). Declaration of Interests: Dr. Gylling reports grants from Nordea Foundation (Centre for Healthy Ageing grant), during the conduct of the study. All other authors declare no conflicts of interest. Ethics Approval Statement: All participants signed an informed consent before participating in the study. The study was approved by the regional ethical committee (Capital Region, Copenhagen, Denmark, No. H-3-2014-017), and complied with the declaration of Helsinki, and the study was approved by the Danish Data Protection Agency.

Biomechanical factors affecting energy cost during running utilising different slopes

ABSTRACTThis study aimed to examine the characteristics of electromyography (EMG) and kinematics of the supporting leg affecting energy cost while running at incline, level, and decline slopes. Twelve male Japanese middle- and long-distance runners volunteered for this study. The subjects were asked to run at 13.5 km·h−1 on a treadmill under three slope conditions. Sagittal plane kinematics and the EMG of the lower limb muscles, respiratory gases were recorded. Energy cost differed significantly between slopes, being the lowest in decline slope and the greatest in incline slope. Integrated EMG (iEMG) of leg extensor muscles was greater in the incline slope than in the decline slope, and iEMG of the gastrocnemius and soleus muscles correlated positively with energy cost. The knee and ankle joint kinematics were associated with energy cost during running. In incline slope, the knee and ankle joints were more extended (plantarflexed) to lift the body. These movements may disturb the coordination between the ankle and knee joints. The gastrocnemius muscle would do greater mechanical work to plantarflex the ankle joint rather than transfer mechanical energy as well as greater mechanical work of mono-articular muscles. These muscular activities would increase energy cost.