Knee Extensor Power Research Articles

Preworkout dietary nitrate magnifies training-induced benefits to physical function in late postmenopausal women: a randomized pilot study.

To inform end points for future work, we explored the utility of preworkout (i.e., an acute dose before training) beetroot juice (BRJ) combined with exercise (BRJ + EX) to augment indices of physical function in postmenopausal women compared with exercise only (EX). A two-arm pilot study was used to compare 24 postmenopausal women following an 8-wk, circuit-based exercise intervention. Participants were randomized to BRJ + EX (n = 12) or EX (n = 12). BRJ + EX participants consumed 140 mL of BRJ 120-180 min (only) before training for 7 wk, then discontinued during the final week to mitigate carryover effects. Physical function indices were 6-min walk test (6MWT), estimated V̇o2peak, heart rate recovery (HRR), and maximal knee extensor power (Pmax). A treadmill task was used to measure V̇o2 on-kinetics wherein mean response time (MRT) coincided with the duration to reach 63% of steady-state V̇o2. Results showed greater changes (Δ) among BRJ + EX participants for 6MWT distance (40 ± 23 m vs. 8 ± 25 m; P = 0.003, d = 1.35), ΔV̇o2peak (1.5 ± 0.9 mL·kg-1·min-1 vs. 0.3 ± 1.0 mL·kg-1·min-1; P = 0.008, d = 1.20), and ΔHRR (-10 ± 6 beats/min vs. -1 ± 9 beats/min; P = 0.017, d = 1.05). Large and medium effect sizes favoring BRJ + EX were detected for ΔPmax (P = 0.07, d = 0.83) and ΔMRT (P = 0.257, d = 0.50), respectively. In postmenopausal women, BRJ + EX appears to magnify some adaptive benefits to physical function including aerobic capacity and recovery beyond that of training without BRJ. Investigation into contributing mechanisms is needed.NEW & NOTEWORTHY Though exercise training represents the principal strategy to combat age-related decline, the attendant effects of menopause weaken aspects of exercise adaptation compared with premenopausal women and age-matched men. Here we provide important initial evidence that preworkout (i.e., an acute dose before training) beetroot juice coupled with an 8-wk, circuit-based exercise training intervention may uniquely benefit late postmenopausal women by enhancing indices of physical function including aerobic capacity and recovery.

Enhancing physical and cognitive function in older adults through walking & resistance exercise: Korean national aging project randomized controlled study

BackgroundThe rapid aging of Korea's population underscores the urgent need for effective programs to enhance the well-being and longevity of the elderly. This study presents preliminary results from the Korean project, examining the impact of cost-effective and accessible exercise programs on functional performance of older people and to determine the long-term maintenance of intervention. MethodsWe randomized 90 older adults aged ≥65 years to the walking group (WG), resistance + walking (RWG), or active control (CG) group. We designed a 12-week main intervention (supervised resistance training 2 d/week and individual walking exercise) and a 12-week follow-up through self-directed exercise (same protocol but unsupervised). The participants’ mini mental state examination, color-word Stroop test and 5-time sit to stand, timed up & go, handgrip strength, and knee extensor strength tests were assessed at pre, post, as well as follow-up. ResultsFor the RWG group, significant improvements were found in timed up & go (P < 0.001), and 5-time sit to stand (P < 0.001) compared to CG, with benefits maintained at follow-up. Both RWG and WG showed significant enhancements in knee extensor power (RWG: P < 0.0001; WG: P < 0.001) and flexor power (RWG: P < 0.01; WG: P = 0.018) compared to CG. Although cognitive performance did not show significant group-by-time interactions, RWG exhibited improvements in the Stroop Color and Color-Word tests at follow-up compared to baseline. ConclusionA resistance training program combined with walking effectively enhanced functional performance in older adults, providing lasting benefits over 12 weeks on physical functions, such as strength and endurance. However, it showed limited benefits on cognitive performance.

30-sit-to-stand power is a better tool than isometric knee extensor strength to detect motor impairment in people with haemophilic arthropathy.

Regular assessment of motor impairments is crucial in people with haemophilic arthropathy (PwHA). This study aimed to determine if there are differences in 30-secondssit-to-stand (30-STS) power and maximal voluntary isometric contraction (MVIC) of the knee extensors between PwHA and healthy control group (CG). The secondary aims were to investigate the correlation between 30-STS power and MVIC of knee extensors with clinical characteristics and to assess their effectiveness in identifying motor impairment in PwHA. A cross-sectional study was conducted by collecting data from PwHA (n=17) and a sedentary CG (n=15). MVIC (torque) and 30-STS power were normalised to body mass. Correlation analysis and simple linear regression adjusted for age were used to assess the association between tests and clinical variables. Using z-scores derived from the mean and standard deviation of the CG, we compared the MVIC and the 30-STS power in PwHA. PwHA showed lower MVIC and 30-STS power compared to CG (p<.001; large effect size d>.8). Lower 30-STS power was associated with greater joint impairment and greater fear of movement, whereas MVIC showed no association with clinical variables. 30-STS power showed a lower z-score compared to MVIC (p<.001). In addition, 30-STS power detected 47% of PwHA with motor impairment compared to 0% for MVIC (p=.002). Our results suggest that 30-STS power may be more effective than knee extensors MVIC in detecting motor impairment in PwHA. Consequently, lower limb skeletal muscle power, rather than maximum knee extensor strength, appears to be more affected in PwHA.

Feasibility of Mobile Health App-Based Home Aerobic Exercise for Physical Performance in Healthy Young Adults.

To investigate the feasibility and effects of a mobile app-based home cycling exercise program compared to home cycling exercise without additional monitoring system. Compared with fitness facilities or outdoor exercise, home-based exercise programs effectively improve physical performance in an indwelling community. However, a flexible, informal environment may decrease motivation and impair adherence to physical exercise. Mobile devices for aerobic exercise and mobile applications provide real-time monitoring, immediate feedback, and encouragement to increase motivation and promote physical performance. We investigated the feasibility and effects of a mobile app-based home exercise program on body composition, muscular strength, and cardiopulmonary function. Between February and May 2023, 20 participants were randomly allocated to the intervention (mobile application with a tablet) and control groups, and they performed aerobic exercise using a stationary bicycle for ≥150 minutes per week for 6 weeks (≤30-minute exercise session, with 3-minute warm-up and 3-minute cool-down). Karvonen formula-based heartrate defined the weekly increase in exercise intensity. Outcome measures included body-composition parameters, isokinetic knee flexor and extensor strength tests, cardiopulmonary exercise test results, and rate of target heart rate (HR) achievement. Participants were assessed at baseline and after the intervention. Unrelated personal events led two participants to drop out. The intervention and control groups had similar baseline characteristics. Compared with the control group, in the post-intervention isokinetic strength test, bilateral knee flexor and extensor power, and time to target HR achievement significantly increased each week in the intervention group. Home-based exercise to achieve long-term cardiovascular fitness with portable electronic/mobile devices facilitates individualized exercise using real-time feedback to improve motivation and adherence.

A Comparison of a Step Load Unilateral and Bilateral Resistance Training Program on the Strength and Power of the Lower Limbs in Soccer Players

The purpose of the investigation was to determine the influence of a four-week unilateral (UNI) and bilateral (BIL) resistance training program on peak torque and peak power of the lower limbs in soccer players. Background: We evaluated the effects of a 3:1 step load training program using UNI and BIL forms of exercises on the level of peak torque and peak power of the knee joint extensors and flexors. Methods: The study included 16 division I soccer players having the highest number of matches played in the first round of the season. The motor tests included isokinetic evaluation of peak torque and peak power of the extensors and flexors of the knee joint. Results: The results showed that both types of training sessions were equally effective. Only in terms of power during knee flexion, unilateral training contributed to improvement, whereas bilateral training did not. Conclusions: The use of periodization using a step load progression based on an extended eccentric phase of the movement during the preseason period in combination with UNI training may increase peak torque and peak power of knee flexors and extensors in soccer players.

Effects of blood flow restriction training on muscle fitness and cardiovascular risk of obese college students.

Purpose: The aim of this study was to investigate the effect of blood flow restriction (BFR) combined with low-intensity resistance training (RT) on cardiovascular risk factors in obese individuals. Methods: Twenty-six male obese college students were recruited and randomly assigned to a control group (CON, n = 8), a low-intensity RT group (RT, n = 9), and a combined BFR training and low-intensity RT group (BFRT, n = 9). Results: The subjects in BFRT group showed significant reductions in body fat percentage and waist-to-hip ratio and a significant increase in lean mass and muscle mass; the peak torque, peak power, and endurance ratio of knee extensors and elbow flexors were significantly upregulated; the root mean square (RMS) for the medial femoral muscle, lateral femoral muscle and biceps significantly increased; the diastolic blood pressure (DBP) showed a significant decrease. The BFRT group also showed significant up-regulations in RMS of the difference between the adjacent R-R intervals (RMSSD), high-frequency power (HF) of parasympathetic modulatory capacity, the standard deviation of R-R intervals (SDNN) of overall heart rate variability (HRV) changes and low-frequency power (LF) of predominantly sympathetic activity. In addition, glycated hemoglobin (HbA1C), insulin resistance index (HOMA-IR) and fasting blood glucose (FBG) were all significantly downregulated in BFRT group. In parallel, low-density lipoprotein (LDL-C) significantly reduced while high-density lipoprotein (HDL-C) significantly increased in BFRT group. Conclusion: BFR combined with low-intensity RT training effectively improved body composition index, increased muscle mass, improved neuromuscular activation, enhanced muscle strength and endurance, which in turn improved abnormal glucolipid metabolism and enhanced cardiac autonomic regulation.

Exploring How Older Adult's Gender Role is Associated with Studied Outcomes Following an Outdoor Exercise Structure Program.

This study aimed to describe the gender roles of people interested in an exercise program done on outdoor exercise structures and test if gender roles were associated with studied outcomes. Older adults aged 65+ who were not currently performing resistance training were invited to participate. Gender roles were quantified using the Bem Sex Role Inventory 30-item questionnaire (-60 [feminine] to +60 [masculine]). Outcomes included completing the 6-week intervention (Y/N) and changes in physical function (one leg stance, 30-s chair stand), strength (predicted maximal chest press and leg press, grip strength), power (knee extensor power), and overall health via the SF-36 questionnaire. Twenty-nine adults (65.5% female; median 72 years old) participated in the study, and 17 completed the intervention (58.6%). The median (interquartile) gender role score was -13.0 (-19.5 to -8.5), with no gender role difference (p = .62) between completers and non-completers. These results suggest that older adults interested in such a program portray themselves as more feminine. No association was found between gender role scores and changes in any study outcomes. In this setting, gender roles did not seem to impact the study outcomes and therefore may not need to be considered when designing an outdoor exercise structure program.

The effects of crank power and cadence on muscle fascicle shortening velocities, muscle activations and joint-powers during cycling.

Whilst people typically chose to locomote in most economical fashion, during bicycling they will, unusually, chose cadences that are higher than metabolically optimal. Empirical measurements of the intrinsic contractile properties of the vastus lateralis (VL) muscle during submaximal cycling suggest that the cadences that people self-selected (SSC) might allow for optimal muscle fascicle shortening velocity for the production of knee extensor muscle power. It remains unclear, however, whether this is consistent across different power outputs where the SSC varies. We examined the effect of cadence and external power requirements on muscle neuromechanics and joint powers during cycling. VL fascicle shortening velocities, muscle activations and joint-specific powers were measured during cycling between 60 and 120rpm (including SSC), while participants produced 10%, 30%, and 50% of peak maximal power. VL shortening velocity increased as cadence increased but was similar across the different power outputs. Although no differences were found in the distribution of joint powers across cadence conditions, the absolute knee joint power increased with increasing crank power output. Muscle fascicle shortening velocities increased in VL at the SSC as pedal power demands increased from submaximal towards maximal cycling. A secondary analysis of muscle activation patterns showed minimized activation of VL and other muscles near the SSC at the 10% and 30% power conditions. Minimization of activation with progressively increasing fascicle shortening velocities at the SSC may be consistent with the theory that the optimum shortening velocity for maximizing power increases with intensity of exercise and recruitment of fast twitch fibers.

Countermovement Jump Performance Is Related to Ankle Flexibility and Knee Extensors Torque in Female Adolescent Volleyball Athletes.

Ankle flexibility and isokinetic knee torque/power generating capacity were previously suggested to contribute or to be correlated to the vertical countermovement jump (CMJ) performance. The aim of this study was to investigate the effect of the passive ankle joint dorsi flexion (θPDF) and the knee muscle's isokinetic torque and power on the CMJ in adolescent female volleyball players. The θPDF at a knee extension angle of 140 degrees were measured for 37 female post-pubertal volleyball players. Then, the players were assigned to either the flexible (n = 10) or inflexible (n = 14) groups according to earlier recommended criteria. Testing included the CMJ with and without an arm swing, and maximal knee extensions and flexions in 3 angular velocities on an isokinetic dynamometer. CMJ height performed with or without an arm swing (r(22) = 0.563, p = 0.040 and r(22) = 0.518, p = 0.009, respectively) and relative power (r(22) = 0.517, p = 0.010 and r(22) = 0.446, p = 0.030, respectively) were positively correlated with the extensors' torque at 180°/s and were negatively correlated with the flexibility level of the dominant side ankle (r(22) = -0.529, p = 0.008 and r(22) = -0.576, p = 0.030, respectively). A moderate positive correlation was also revealed between the CMJ height with and without an arm swing and the power of the non-dominant knee extensors (r(22) = 0.458, p = 0.024 and r(22) = 0.402, p = 0.049, respectively) and flexors (r(22) = 0.484, p = 0.016 and r(22) = 0.477, p = 0.018, respectively). Results of the 2 × 2 repeated ANOVA measurements revealed that flexible players jumped significantly (p < 0.05) higher during the CMJs, whilst there was a group effect only on the isokinetic knee extensor muscles' torque. In conclusion, a more flexible ankle joint and a higher isokinetic knee extensor's torque generating capacity resulted in higher CMJ performance. Therefore, ankle flexibility should be emphasized in training and is suggested to be included in preseason screening tests of youth female volleyball players.

Short-term beetroot juice supplementation improves muscle speed and power but does not reduce blood pressure or oxidative stress in 65–79 y old men and women

We have previously demonstrated that acute ingestion of inorganic nitrate (NO3−)-rich beetroot juice (BRJ), a source of nitric oxide (NO) via the NO3− → nitrite (NO2−) → NO pathway, can improve muscle speed and power in older individuals. It is not known, however, whether this effect is maintained or perhaps even enhanced with repeated ingestion, or if tolerance develops as with organic nitrates, e.g., nitroglycerin. Using a double-blind, placebo-controlled, crossover design, we therefore studied 16 community-dwelling older (age 71 ± 5 y) individuals after both acute and short-term (i.e., daily for 2 wk) BRJ supplementation. Blood samples were drawn and blood pressure was measured periodically during each ∼3 h experiment, with muscle function determined using isokinetic dynamometry. Acute ingestion of BRJ containing 18.2 ± 6.2 mmol of NO3− increased plasma NO3− and NO2− concentrations 23 ± 11 and 2.7 ± 2.1-fold over placebo, respectively. This was accompanied by 5 ± 11% and 7 ± 13% increases in maximal knee extensor speed (Vmax) and power (Pmax), respectively. After daily supplementation for 2 wk, BRJ ingestion elevated NO3− and NO2− levels 24 ± 12 and 3.3 ± 4.0-fold, respectively, whereas Vmax and Pmax were 7 ± 9% and 9 ± 11% higher than baseline. No changes were observed in blood pressure or in plasma markers of oxidative stress with either acute or short-term NO3− supplementation. We conclude that both acute and short-term dietary NO3− supplementation result in similar improvements in muscle function in older individuals. The magnitudes of these improvements are sufficient to offset the decline resulting from a decade or more of aging and are therefore likely to be clinically significant.

Focal muscle spasticity has little impact on muscle power for walking in people with Traumatic Brain Injury

BackgroundSpasticity is prevalent following Traumatic Brain Injury. ‘Focal’ muscle spasticity has been defined as spasticity affecting a localised muscle group, but it's impact on gait kinetics remains unclear. The aim of this study was to investigate the relationship between focal muscle spasticity and gait kinetics following Traumatic Brain Injury. MethodsNinety-three participants attending physiotherapy for mobility limitations following Traumatic Brain Injury were invited to participate in the study. Participants underwent clinical gait analysis and were grouped depending on the presence or absence of focal muscle spasticity. Kinetic data was obtained for each sub-group, and participants were compared to healthy controls. FindingsHip extensor power generation at initial contact, hip flexor power generation at terminal stance, and knee extensor power absorption at terminal stance were all significantly increased, and ankle power generation was significantly reduced at push-off when comparing Traumatic Brain Injury to healthy control populations. There were only two significant differences between participants with and without focal muscle spasticity, hip extensor power generation at initial contact was increased (1.53 vs 1.03 W/kg, P < .05) for those with focal hamstring spasticity, and knee extensor power absorption in early stance was reduced (−0.28 vs −0.64 W/kg, P < .05) for those with focal rectus femoris spasticity. However, these results should be interpreted with caution as the sub-group of participants with focal hamstring and rectus femoris spasticity was small. InterpretationFocal muscle spasticity had little association with abnormal gait kinetics in this cohort of independently ambulant people with Traumatic Brain Injury.

Reliability, Validity and Minimal Detectable Change of a Power Leg Press Test in Individuals with Cerebral Palsy

Background Lower extremity muscle power influences walking ability in individuals with Cerebral Palsy (CP). Aim Determine the reliability, validity, and minimal detectable change (MDC) of a novel power leg press (PLP) test to measure muscle power in individuals with CP. Methods Individuals with spastic CP (n = 26 (10 adults, 16 children); mean (SD) age = 19.3 (7.8) years(all); 27.9 (4.89) years (adults); 13.85(2.68) years (children)) performed 2 sessions of the PLP test, 2–10 days apart. A linear position transducer and custom computer code were used to calculate mean and peak power in watts (W). Intraclass correlation coefficients (ICC), standard error of measurement, MDC, and percent change of MDC (MDC%) were calculated for 4 power measures (average and maximum of mean and peak powers) for all participants (AP) and separately for adults (A) and children (C). Validity was evaluated against isokinetic knee extensor power. Results Test-retest reliability was excellent for all measures of power (ICC = 0.94–0.99). Ranges for MDC/MDC% by the group for power measures were between 33.7–80.7W/15.5–29.4% (AP), 41.1–65.3W/10.7–22.3% (A), and 27.6–79.8W/19–34.3% (C). Correlations were good to excellent between PLP and isokinetic power at all speeds (r = 0.75–0.88, p < .001). Conclusions The PLP test demonstrates excellent validity, reliability, and precision for measuring muscle power in those with CP.

Comparison by Gender of Muscle Power of Knee Extensors and Flexors of Athletics Athletes from the National Training and Athletics Center of the University of Fortaleza, Ceará, Brazil

The objective of this study was to compare the muscular power of the extensors and flexors of track and field athletes from the National Training and Athletics Center of the University of Fortaleza by male and female gender and not by event. Ten women and six men were evaluated, totaling 16 athletes, using the Cybex® brand isokinetic. The isokinetic evaluation has been used in many studies to evaluate the potency among other valences.

Effects of multidomain interventions on skeletal muscle architecture and function in pre-frail older women: The WiiProtein study

The aim was to investigate the effects of physical training with exergames and protein supplementation on musculoskeletal function, muscle architecture, and markers of physical frailty in pre-frail older women. Ninety participants were assigned to one of five groups: physical training using exergames (PTG); protein supplementation (PSG); physical training and protein supplementation (PTPSG); physical training and isoenergetic supplementation (PTISG); and control group (CG). We evaluated: strength and power of lower limbs; functional mobility; gait speed; handgrip strength; and muscle architecture. The PTPSG increased knee extensor and flexor strength (8.4% and 10.2% respectively), and knee extensor power (17.1%), reduced exhaustion (100%), and also reversed pre-frailty (43.8%). There were no significant differences among groups in all outcomes analyzed. Physical training using exergames with protein supplementation increased musculoskeletal function, reduced exhaustion, and reversed pre-frailty in older women.

Utility of ultrasound as a promising diagnostic tool for stroke-related sarcopenia: A retrospective pilot study.

Stroke patients undergo extensive changes in muscle mass which lead to stroke-related sarcopenia. Stroke-related sarcopenia has a significant impact on the functional outcome of stroke survivors. So, it is important to measure muscle mass in stroke patients. This study aimed to examine the correlation between ultrasonographic quadriceps muscle thickness (QMT) and dual-energy X-ray absorptiometry (DXA) derived appendicular lean mass (ALM) in patients with acute hemiplegic stroke. Twenty five participants were included (13 men and 12 women) in this study, who were diagnosed with stroke within 1 month. For both paretic and non-paretic legs, QMT was measured by an ultrasound and ALM was obtained by performing DXA scan. We analyzed the difference and the correlation between ultrasonographic QMT and DXA-derived lean body mass of both paretic and non-paretic legs. Stroke patients were divided into 2 groups according to the paretic knee extensor power. Ultrasonographic QMT, DXA scan findings, and functional parameters were compared. There was a significant correlation between QMT and ALM index, and between QMT and site-specific lean mass (SSLM) of both the legs for both the sexes (P < .05). In multivariate linear regression model, we made adjustments for the confounding factors of age, sex, body mass index (BMI) and paretic knee extensor power. We observed a positive relationship between QMT and ALM index (P < .05), and between QMT and SSLM of both the legs (P < .05). The % QMT showed higher difference than % SSLM between paretic and non-paretic legs (10.25% vs 4.58%). The QMT measurements of ultrasound show a great relationship with DXA scan findings. Ultrasound better reflects the change of muscle mass between paretic and non-paretic legs than DXA scan at an acute phase of stroke. Ultrasound could be a useful tool to evaluate stroke-related sarcopenia.

The association between the serum vitamin D levels and the stroke lesion size, functional ability, and cognition in elderly Korean ischemic stroke patients

The purpose of this study was to confirm the association between the serum vitamin D levels and ischemic stroke lesion size, functional ability, and cognitive function in elderly ischemic stroke patients. This study included Korean ischemic stroke patients aged 65 to 85 years. The size of the lesion was measured in brain images taken within 24 hours of hospitalization. The level of 25-(OH) Vitamin D (ng/mL), a metabolite of vitamin D, in the serum collected within 48 hours of hospitalization, and the modified Barthel index (MBI), gait performance, the muscle power of hip and knee extensors on the hemiplegic side, and mini-mental status examination (MMSE) were recorded within 1 week of the onset of the disease. Each factor was compared through correlation analysis, and the significance was confirmed using the Spearman correlation coefficient method. The association between the serum vitamin D levels and the size of the ischemic stroke lesion, the MBI, gait performance, the muscle power of hip and knee extensors on the hemiplegic side, and the MMSE were analyzed. It was confirmed that there was a significant correlation between all the factors (P < .005). In patients with serum vitamin D levels of ≥ 30 ng/mL, both the functional ability and cognitive functions were better than in patients lower than 30 ng/mL. We confirmed the lower the level of serum vitamin D levels, the larger the size of the ischemic stroke lesion when it occurred in elderly Koreans. And we confirmed that serum vitamin D levels affected the functional ability and cognitive function. And we recommend that elderly Koreans should maintain their blood vitamin D level above 30 ng/mL. We believe that this will help preserve the functional ability and cognitive function when ischemic stroke occurred.

Weight Loss And Exercise Effects On Torque Development And Physical Function In Overweight Older Women

PURPOSE: Obesity negatively impacts lower extremity physical function [LEPF] and is associated with loss of independent living in part due to reduced muscle quality and capacity, especially in older women. Concurrent exercise/physical activity and weight loss interventions have been shown to improve LEPF. However, the inclusion of power modulations, specifically rate of torque development [RTD] parameters in response to these interventions has not been investigated. The aim of this study was to determine the effects of weight loss, with or without exercise training, on RTD parameters and their potential impact on LEPF in overweight physically inactive older women. METHODS: This project involved a secondary data analysis from a 6-month parent project that involved weight loss involving different dietary regimens with or without exercise. Overweight inactive postmenopausal women (n = 44, 69.1 ± 3.6 yrs; 30.6 ± 4.3 kg/m2) completed the trial within two groups: 1) exercise and weight loss [EX+WL; (N = 30)] and weight loss alone [WL; (N = 14)]. Knee flexor and extensor strength and power were assessed via a maximum voluntary contraction [MVIC] using an isokinetic dynamometry with RTD parameters [RTD200 = RTD at 200 ms, RTDPeak = Peak RTD and T2P = Time to 1st Peak]. LEPF was assessed via 6-min walk, 8-ft up and go, and 30-s chair stand. RESULTS: Weight loss was similar in the groups (-7.1 ± 4.1 kg; -9.8 ± 4.2%, p > 0.95) whereas EX+WL had greater improvements in most LEPF tasks (p < 0.001). EX+WL had a greater increase in RTD200 Flexion compared with WL (36% vs. -16%, p = 0.031), with no other differences in RTD parameters observed. No significant regression models were observed predicting change in LEPF performance from changes in RTD parameters (all p > 0.05). CONCLUSIONS: These findings suggest weight loss, which incorporates exercise training, can improve LEPF and rate of torque development in overweight/obese physically inactive older women, yet these improvements do not appear to transfer to improvements in physical function task performance

Ischemic Conditioning And Fatigability Of The Knee Extensors In Young And Older Adults

Aging is associated with impaired vascular function, reduced ability to generate muscular power, and increased limb fatigability (exercise-induced loss of power) for moderate- to high-velocity contractions. Ischemic conditioning is an intervention that can improve these areas of function in young adults and some diseased populations, yet its effects in older adults are unknown. PURPOSE: Determine the effect of ischemic conditioning on fatigability, power output, and exercising vascular function of the knee extensor muscles in young and older adults. METHODS: Knee extensor fatigability, power output, and vascular function were quantified in 10 young (23 ± 3 yr; 6f/4 m) and 11 older (74 ± 4 yr; 4f/7 m) adults after receiving ischemic conditioning (IC) and sham (SHAM) interventions on separate days. IC consisted of 4 sets of 5 min proximal thigh occlusion at 250 mmHg (20 mmHg for SHAM) with 5 minutes rest between sets. The fatiguing exercise consisted of 80 maximal-velocity contractions (1 contraction every 3-s) of the knee extensors lifting a load equivalent to 20% of the maximal voluntary isometric contraction. Superficial femoral artery blood flow was measured before and immediately after exercise using doppler ultrasonography. Muscle oxygenation (StO2) was measured during exercise with near-infrared spectroscopy. RESULTS: Fatigability (percent reduction in power) was not different between IC and SHAM in young (85 ± 12 v. 87 ± 8%) or older adults (70 ± 25 v. 70 ± 19%) [both p > 0.05], nor was power output at the start of the dynamic task in young (215 ± 55 v. 218 ± 60 W) or older adults (122 ± 45 v. 117 ± 46 W) [both p > 0.05]. Blood flow (% change pre- to post-exercise) did not differ between IC and SHAM in young (575 ± 96% v. 561 ± 87%) or older adults (404 ± 84% v. 380 ± 76%) [both p > 0.05]. StO2 was also not different between IC and SHAM in young (50 ± 10 v. 50 ± 8 A.U) or older adults (46 ± 5 v. 45 ± 7 A.U.) [both p > 0.05], nor was deoxy[heme] in young (24 ± 9 v. 24 ± 10 A.U.) or older adults (27 ± 8 v. 27 ± 5 A.U) [both p > 0.05]. CONCLUSIONS: Ischemic conditioning did not alter fatigability, power output, bulk blood flow, or oxygenation in the lower limb of young or older adults. These findings suggest ischemic conditioning is not an effective strategy for improving muscle or vascular function during high-velocity contractions in young and healthy older adults.

Loaded Functional Strength Training versus Traditional Physical Therapy on Hip and Knee Extensors Strength and Function Walking Capacity in Children with Hemiplegic Cerebral Palsy: Randomized Comparative Study.

Objective: This study’s objective was to see how loaded functional strengthening exercises using a plantigrade foot position and a shoe supporter affected muscle strength and walking ability in spastic hemiplegic children. Methods: Seventy-two children with spastic hemiplegic cerebral palsy, both sexes, aged ten to twelve years, were randomly assigned into two groups equal in number (control and intervention groups). The control group received a specially designed physical therapy program, whereas the intervention group received a loaded functional strengthening exercises program using a shoe supporter to maintain a plantigrade foot position. The training program was carried out for 60 min, three times per week for three consecutive months. All participants were evaluated both before and after the therapy program by using a Medical Commander Echo Manual Muscle Tester dynamometer to assess isometric muscle power of hip and knee extensors on the affected side. To assess functional walking capacity, a 6 min walking (6MWT) test was used. Results: Study groups were comparable with respect to all outcome measures at entry (p > 0.05). Within-group comparison showed significant improvements in all measured variables. Furthermore, between-group comparison revealed significantly greater improvements (p < 0.05) in hip and knee extensors strength as well as the functional walking capacity in favor of the intervention group. Conclusions: In all the analyzed variables, loaded functional strength exercises from the plantigrade foot position were found to be considerably more effective in the intervention group than in the control group.

Role of Knee and Ankle Extensors' Muscle-Tendon Properties in Dynamic Balance Recovery from a Simulated Slip.

Participants exposed to a simulated slip with forward loss of balance (FLB) develop large lower limb joint moments which may be a limiting factor for those whose muscle-tendon units’ (MTUs) properties are deteriorated. Whether the age-related decline in these properties limits participants’ capacity to recover their balance following a slip with FLB remains unclear. We combined isokinetic dynamometry, ultrasound and EMG to understand how knee extensor and ankle plantarflexor muscle strength and power, rate of moment development, electromechanical delay, and tendon stiffness affected the balance of young (25.3 ± 3.9 years) and older adults (62.8 ± 7.1 years) when recovering from a single slip with FLB triggered whilst walking on a split-belt instrumented treadmill. Except for the patellar tendon’s stiffness, knee extensor and ankle plantarflexor electromechanical delays, older adults’ MTUs properties were deteriorated compared to those of young participants (p < 0.05). We found no significant relationship between age or the MTUs properties of participants and balance recovery. These findings provide additional support that neither maximal nor explosive strength training are likely to be successful in preventing a fall for healthy older adults, and that other type of interventions, such as task-specific training that has already proved efficacious in reducing the risk of falling, should be developed.