Effects of Eccentric Speed during Front Squat Conditioning Activity on Post-activation Performance Enhancement of Hip and Thigh Muscles

The phenomenon of post-activation performance enhancement plays an unidentified role in movement eccentric speed and individual muscle group responses. Therefore, this study aimed to determine whether the loaded front squat (FSq) speed of the eccentric phase would influence the post-activation performance enhancement effect and whether the FSq would elicit similar performance enhancement of knee flexion, knee extension, hip flexion, and hip extension muscles. Twenty resistance-trained handball players performed the FSq under maximum eccentric-concentric speed and 2-s eccentric speed (only the eccentric phase performed), while pre- and post-front squat countermovement jump, knee, and hip isokinetic flexion/extension performance were tested. The FSq conditioning activity was performed in a single set of three repetitions with either 90% (maximum eccentric-concentric speed) or 120% (2-s eccentric speed) of one repetition maximum, and post-performance was measured 4-12 min after the FSq. Athletes randomly changed the FSq eccentric speed and tested the hip or knee isokinetic flexion/extension strength at 180°/s. ANOVA showed that the rate of force development during the jump increased (Cohen d = 0.59-0.77) with no differences between 2-s eccentric and maximum speed eccentric protocols. Isokinetic strength increased after the 2-s eccentric FSq in hip extension (d = 0.76-0.86), knee flexion (d = 0.74-0.88), and hip flexion (d = 0.82), with no differences in knee extension strength. After maximum eccentric-concentric speed, isokinetic strength increased in hip extension (d = 1.25). In conclusion, the FSq conditioning activity enhances hip extensors' performance more than knee extensors' performance. Different eccentric types of muscle action during a conditioning activity alter the level of local muscle enhancement.

The effects of power exercises on body structure and function, activity and participation in children with cerebral palsy: an ICF-based systematic review

PURPOSE

To systematically review the literature for evidence of effectiveness of power exercises on physical, physiological, and functional outcomes in children and adolescents with cerebral palsy (CP).

MATERIALS AND METHODS

Methodological quality and evidence synthesis were assessed with using the Cochrane Risk of Bias (RoB) Tools and Modified Bakker Scale. Using the International Classification of Functioning (ICF), outcome measures for muscle agriculture, gait, balance, motor function, aerobic/anaerobic fitness, daily living, mobility, and school participation were categorised.

RESULTS

The overall RoB of four randomised clinical trials was low, one had some concerns and two were rated as high. Moderate evidence was found that power exercises increased walking speed, activities of daily living, muscle strength, and enhanced gross motor function more than a routine physical therapy program.

CONCLUSIONS

The lack of stronger evidence for power training interventions to improve muscle architecture, muscle function, walking capacity, and mobility in children with CP might be explained by the differences in training protocols and degree to which these meet the physiological definition of power, different methods of measuring power, limited durations of training, and the relative effectiveness of control interventions. Future studies should include a stronger focus on child and family-centred participation goals.Implications For RehabilitationPower training can improve gross motor function, walking speed, muscle strength, and activities of daily living more than routine physical therapy.Results comparing power training versus traditional strength training were less pronounced likely because both are intensive and may have positive effects.More research is needed to investigate effects of power training on participation.

Cost-Consequences Analysis Following Different Exercise Interventions in Institutionalized Oldest Old: A Pilot Study of a Randomized Clinical Trial

OBJECTIVES

to investigate the effects of two different exercise interventions on cost of care, functional capacity, falls occurrence, muscle strength, and executive function in institutionalized oldest old.

DESIGN

A pilot study of a randomized clinical trial investigating 12 months of two exercise interventions compared to a usual care group in oldest old residents of a nursing home.

SETTING AND PARTICIPANTS

69 older patients (mean age 89.4 ±5.1 years) completed the full baseline and post intervention measurements. Participants were randomly allocated into multicomponent exercise group (MG, n=23), calisthenics group (CALG, n = 23), and usual care group (UCG, n=23).

METHODS

Primary outcome was individual cost of care, and secondary outcomes included different physical and cognitive functioning tests, as well as number of falls.

RESULTS

MG reduced the cost of care compared to the pre-intervention period, with the greatest difference from baseline achieved in month 12 [mean change 95% confidence interval (CI)=-330.43 (-527.06, -133.80), P=0.006], while UCG increased this outcome, with the greatest difference from baseline observed in month 12 [mean change (95%CI)=300.00 (170.27, 429.72), P=0.013]. In addition, MG significantly improved SPPB score [mean change (95% CI) = 1.21 (0.55, 1.88), P<0.001], whereas the UCG exhibited a decline in scores [mean change (95% CI) = -1.43 (-1.90, -0.97), P<0.001]. Moreover, MG group demonstrated an improvement in the number of falls [mean change (CI 95%) = -1.0 (-1.73, -0.27), P=0.003], while no significant changes were observed in UCG. Additionally, MG exhibited a significant increase in the handgrip strength (HGS) and leg press strength (P<0.001), while a decrease was observed in UCG (P<0.001). No significant changes were observed in the CALG.

CONCLUSIONS AND IMPLICATIONS

a one-year multicomponent exercise intervention reduced the cost of care, improved functional capacity and muscle strength, as well as reduced falls in institutionalized oldest old.

Mental Fatigue Effects on the Produced Perception of Effort and Its Impact on Subsequent Physical Performances

The purpose of this study was to investigate the relationship between mental fatigue induced by a demanding cognitive task and impaired physical performance in endurance due to a higher perception of effort. A total of 12 healthy adults and volunteers, who had previously practiced endurance activities for 4 to 8 h per week, performed a one-hour cognitive task involving either the process of response inhibition (Stroop task) or not (visualization of a documentary as control task), then 20 min of pedaling on a cycle ergometer at a constant perception of effort while cardio-respiratory and neuromuscular functions were measured. The Stroop task induces subjective feelings of mental fatigue (vigor: 3.92 ± 2.61; subjective workload: 58.61 ± 14.57) compared to the control task (vigor: 5.67 ± 3.26; p = 0.04; subjective workload: 32.5 ± 10.1; p = 0.005). This fatigue did not act on the produced perceived effort, self-imposed, and did not affect the cardio-respiratory or neuromuscular functions during the subsequent physical task whose type was medium-term endurance. Regardless of the mental condition, the intensity of physical effort is better controlled when the participants in physical activity control their perception of effort. Mental fatigue does not affect subsequent physical performance but estimated perceived exertion, which increases with the intensity and duration of the exercise.

The Effect of Aquatic Plyometric Training on Jump Performance Including a Four-week Follow-up in Youth Female Volleyball Players

This study aimed to analyze the effect of aquatic plyometric training (APT) on jump performance in volleyball players. Twelve female athletes (16.6 ± 0.9 years) were assessed through the following jump tests: spike height (SH), squat jump (SJ), countermovement jump (CMJ) and CMJ with an arm swing (CMJA). Jump height in each test and the eccentric utilization ratio (EUR) were the outcome measures. APT consisted of sets of drop jumps for 6 weeks (2 sessions/week) at a water depth of 0.75 m. Tests were performed at the beginning of a five-week pre-season period, before and after APT, and four weeks later for the follow-up. Repeated measures ANOVAs were used to analyze data and Hedges’ g to estimate effect size (ES). Performance of all jumps did not change from baseline to Pre-APT. Performance improved in SH (p < 0.001, ES: 1.09), the SJ (p = 0.045, ES: 0.76) and the CMJA (p < 0.001, ES: 0.78) after APT when compared to Pre-APT. No changes were observed after the follow-up period. In conclusion, including six weeks of APT in the training routine of youth volleyball players improved performance of a sport-specific task (SH), the SJ and CMJA, with gains preserved after a four-week follow-up.

Effect of power training on locomotion capacities in children with cerebral palsy with GMFCS level III-IV

PURPOSE

Power training (PT) is a promising training modality to improve functional abilities in children with cerebral palsy (CP). This study aimed to implement PT in an adapted school and to assess its effect on locomotion capacities in children with Gross Motor Function Classification System (GMFCS) level III-IV.

MATERIALS AND METHODS

Nine children with CP (GMFCS level III-IV) were trained three times/week for 12 weeks. The training sessions took place during the 50-minute physical activity classes and included high intensity exercise. The outcome measures were the performance on the 10-meter comfortable and fast walking tests, the 50-meter sprint test (50M-ST), and the energy expenditure index (EEI).

RESULTS

Participants spent 12 ± 7 and 7 ± 9 min per session at an intensity superior to 40% and 60% of the heart rate reserve, respectively. Performance in the 10-meter walking test (13.5 ± 7.8 to 9.9 ± 4.6 s, p < 0.05), the 10-meter fast walking test (8.8 ± 3.1 to 7.0 ± 3.2 s, p < 0.05), the 6-minute walking exercise (199.0 ± 48.6 to 316.6 ± 107.2 m, p < 0.05), and in 50M-ST (53.8 ± 29.5 to 42.3 ± 16.2 s, p < 0.05) increased after training. The EEI was reduced after training (p = 0.01), resulting in a more efficient gait.

CONCLUSIONS

PT was successfully implemented in children with CP with GMFCS level III-IV. Results suggest that PT increases walking capacities.Implications for rehabilitationPower training (PT) is feasible with children with bilateral cerebral palsy with GMFCS level III and IV.Physical education course in specialist school is a valuable environment to implement PT in children with poor gross motor function.Power training results in locomotion capacities improvement.

Efficacy of power training to improve physical function in individuals diagnosed with frailty and chronic disease: A meta-analysis

Muscle power training with emphasis on high-velocity of concentric movement improves physical functionality in healthy older adults, and, maybe superior to traditional exercise programs. Power training may also be advantageous for patients with acute and chronic illnesses, as well as frail individuals. To determine the efficacy of power training compared with traditional resistance training on physical function outcomes in individuals diagnosed with frailty, acute illness or chronic disease. PubMed (MEDLINE), CINAHL, PEDro, Web of Science, and Google Scholar. (1) at least one study group receives muscle power training of randomized controlled trial (RCT) (2) study participants diagnosed as prefrail, frail or have an ongoing acute or chronic disease, condition or illness; (3) study participants over the age of 18; (4) publication in English language; (5) included physical function as the primary or secondary outcome measures. Two independent reviewers assessed articles for inclusion and graded the methodological quality using Cochrane Risk-of-Bias tool for RCTs. Fourteen RCTs met the inclusion criteria. In seven studies, muscle power training was more effective at improving physical function compared to control activities with a mean fixed effect size (ES) of 0.41 (p = 0.006; 95% CI 0.12 to 0.71). Power training and conventional resistance training had similar effectiveness in eight studies with a mean fixed ES of 0.10 (p = 0.061; 95% CI -0.01 to 0.40). Muscle power training is just as efficacious for improving physical function in individuals diagnosed with frailty and chronic disease when compared to traditional resistance training. The advantages of power training with reduced work per session may support power training as a preferential exercise modality for clinical populations. The findings should be interpreted with caution since generalizability is questioned due to the heterogeneity of patient populations enrolled and participants were relatively mobile at baseline.

The Effects of High-Speed Resistance Training on Health Outcomes in Independent Older Adults: A Systematic Review and Meta-Analysis

Human ageing involves several physiological impairments—in particular, a decrease in sensorimotor function and changes in the nervous system reduce muscle strength, power, balance, and functional capacity performance. Preventive strategies are essential to ensure the quality of life of the elderly. High-speed resistance training (HSRT) may be an effective approach to muscle power development in this population, with significant short-term effects on neural adaptations and muscle power production. Therefore, the present study intends to analyze and systematize the studies focused on HSRT interventions and their effects on health outcomes in independent older adults. Four electronic databases (PubMed, Web of Science, EBSCO, and Scielo) were used for the purposes of searching randomized controlled trials that measured at least one key outcome measure focusing on velocity-based training and health outcomes in older adults on 7 March 2022 and identified 1950 studies. At the end of the process, fourteen studies were included in this systematic review and ten studies were included in the quantitative analysis. The main results showed that HSRT interventions would improve health measures, mostly cognitive function (large effects, p = 0.001, SMD = 0.94), neuromuscular function (moderate effects, p = 0.003, SMD = 0.70), and physical function (moderate effects, p = 0.04, SMD = 0.55 and p = 0.009, SMD = −0.59). Additionally, the results suggested that interventions with ten weeks or more, performed three times a week, provide significant improvements in neuromuscular function. In this sense, HSRT is effective for improving overall health outcomes in older adults. Future studies should include proper follow-ups (e.g., minimum six months) to assess the durability of HSRT intervention effects on all health-related variables.

Effect of High Intensity Power Training on Cognitive Function in Older Adults with Type 2 Diabetes: Secondary Outcomes of the GREAT2DO Study

We sought to determine the effects of 12 months of power training on cognition, and whether improvements in body composition, muscle strength, and/or aerobic capacity (VO_2peak) were associated with improvements in cognition in older adults with type 2 diabetes (T2D). Participants with T2D were randomized to power training or low-intensity sham exercise control condition, 3 days per week for 12 months. Cognitive outcomes included memory, attention/speed, executive function, and global cognition. Other relevant outcomes included VO_2peak, strength, and whole body and regional body composition. One hundred and three adults with T2D (mean age 67.9 years; standard deviation [SD] 5.9; 50.5% women) were enrolled and analyzed. Unexpectedly, there was a nearly significant improvement in global cognition (p = .05) in the sham group relative to power training, although both groups improved over time (p < .01). There were significant interactions between group allocation and body composition or muscle strength in the models predicting cognitive changes. Therefore, after stratifying by group allocation, improvements in immediate memory were associated with increases in relative skeletal muscle mass (r = 0.38, p = .03), reductions in relative body fat (r = −0.40, p = .02), and increases in knee extension strength were directly related to changes in executive function (r = −0.41, p = .02) within the power training group. None of these relationships were present in the sham group (p > .05). Although power training did not significantly improve cognition compared to low-intensity exercise control, improvements in cognitive function in older adults were associated with hypothesized improvements in body composition and strength after power training.

Methodological Proposal for Strength and Power Training in Older Athletes: A Narrative Review

INTRODUCTION

Within the adult population, it is not uncommon to meet older athletes who challenge the negative stereotypes associated with aging. Although their physical performance is superior to their sedentary counterparts, they are not immune to impaired neuromuscular function, leading to a decreased physical capacity and an increased risk of injuries. Despite the abundant information about the benefits of strength/power training in advanced ages, there are no methodological proposals that guide physical activity professionals to program this type of training.

OBJECTIVE

This study aimed to review the factors related to the decrease in sports performance within older athletes and the benefits of a strength/power program in order to provide a methodological proposal to organize training in this population.

METHODS

This is a review article. First, databases from PubMed, Science Direct, and SPORTSDiscus and search engines, namely Google Scholar and Scielo, were reviewed, using standard keywords such as strength and power training, evaluation of physical performance, neuromuscular function, and risk of injury in the elderly athlete. All related articles published during the period 1963 to 2020 were considered. A total of 1837 documents were found. By removing 1715 unrelated documents, 122 articles were included in the study after revision control.

RESULTS

Strength/power training is key to alleviating the loss of performance in older athletes and the benefits in neuromuscular function, which helps reduce the rate of serious injuries, maintaining sports practice for a longer period of time. In order to design an appropriate program, a prior evaluation of the individual's physical-technical level must be carried out, respecting the biologicalpedagogical principles and safety regulations.

CONCLUSION

The methodological proposal delivered in this review can serve as a technical guide for physical activity professionals, which will be able to structure the strength/power training and thus preserve the sports practice in older athletes for a longer time.

Effects of Power Training on Gait, Power, and Function in Children with Cerebral Palsy

AIMS

This scoping review aims to: 1) examine available literature regarding the effects of power training on gait speed, power, and function in ambulatory children with CP and 2) identify the variations in exercise dosage and rehabilitation recommendations for power training and plyometrics in children with CP.

METHODS

Four databases (PubMed, CINAHL, Embase, and Cochrane) were searched for papers including power or plyometric training with outcome measures for gait, power or functional performance. ES was calculated for RCTs. Cohorts and case series/studies were evaluated qualitatively.

RESULTS

Ten articles fit search criteria: four RCTs, three cohort studies, one case series, and two case studies. Power training consistently demonstrated improvements in muscle power compared to its effects on gait and function. ES of mean MPST (W) ranged from 0.36-1.13. 1 MWT and SSGS ES were 1.31 and 1.15, respectively. TUG ES ranged from -0.33 to -2.42. ES for GMFM-66 was 0.13 and 1.11 for Dimension D and Dimension E, respectively.

CONCLUSIONS

There is limited, but promising evidence to support that power training may improve gait speed, power, and function in children with CP. Future, more robust research is required to examine effects in a larger, diverse population, to determine long-term effects and exercise prescription.

Acute Blood Pressure Response to High- and Moderate-Speed Resistance Exercise in Older Adults With Hypertension

An increase in blood pressure (BP) occurs during resistance exercise; attention to this response may be necessary in older individuals with hypertension. We compared the BP responses following high- (HSRE) and moderate-speed resistance exercise (MSRE) (4 × 8 repetitions at 60% one-repetition maximum) and control protocol in 15 older adults with hypertension. HSRE and MSRE increased systolic BP (SBP) by the end of each set compared with preexercise and control protocol. Immediately after the fourth set, a higher SBP was observed in MSRE than HSRE (147 ± 14 vs. 141 ± 12 mmHg; p = .01). Taking an exploratory analysis of the individual response, we observed that MSRE resulted in greater mean changes and number of SBP exposures to values ≥150 mmHg (22-fold) than HSRE (10-fold). Diastolic BP increased (p < .05) with exercise, but only MSRE increased compared with the control condition (p < .05). HSRE may be an alternative for individuals in which SBP peak should be avoided.

Krill-Oil-Dependent Increases in HS-Omega-3 Index, Plasma Choline and Antioxidant Capacity in Well-Conditioned Power Training Athletes

There is evidence that both omega-3 polyunsaturated fatty acids (n-3 PUFAs) and choline can influence sports performance, but information establishing their combined effects when given in the form of krill oil during power training protocols is missing. The purpose of this study was therefore to characterize n-3 PUFA and choline profiles after a one-hour period of high-intensity physical workout after 12 weeks of supplementation. Thirty-five healthy power training athletes received either 2.5 g/day of Neptune krill oil^TM (550 mg EPA/DHA and 150 mg choline) or olive oil (placebo) in a randomized double-blind design. After 12 weeks, only the krill oil group showed a significant HS-Omega-3 Index increase from 4.82 to 6.77% and a reduction in the ARA/EPA ratio (from 50.72 to 13.61%) (p < 0.001). The krill oil group showed significantly higher recovery of choline concentrations relative to the placebo group from the end of the first to the beginning of the second exercise test (p = 0.04) and an 8% decrease in total antioxidant capacity post-exercise versus 21% in the placebo group (p = 0.35). In conclusion, krill oil can be used as a nutritional strategy for increasing the HS-Omega-3 Index, recover choline concentrations and address oxidative stress after intense power trainings.

Intramuscular hyaluronic acid expression following repetitive power training induced nonfunctional overreaching

Hyaluronic acid (HA) contributes to extracellular matrix viscosity and fiber regeneration. HA role in resistance training (RT) performance adaptations is unclear. RT men performed power training (nonfunctional overreaching (NFOR) or normal training (CG)) over 7.5 days. Post RT, the CG improved power while NFOR did not with HA content decreasing 34.5% in NFOR with no change in CG. HA is critical for muscular recovery; decreased HA may contribute to impaired power adaptations with NFOR RT. Novelty: Nonfunctional over-reaching decreases muscular hyaluronic acid.

Effects of Low-Speed and High-Speed Resistance Training Programs on Frailty Status, Physical Performance, Cognitive Function, and Blood Pressure in Prefrail and Frail Older Adults

Aim: The current study investigated the effects of low-speed resistance training (LSRT) and high-speed resistance training (HSRT) on frailty status, physical performance, cognitive function and blood pressure in pre-frail and frail older people.

Material and Methods: Sixty older adults, 32 prefrail and 28 frail, were randomly allocated into LSRT, HSRT, and control group (CG). Before and after intervention periods frailty status, blood pressure, heart rate, and a set of physical performance capabilities and cognitive domains were assessed. Exercise interventions occurred over 16 weeks and included four resistance exercises with 4–8 sets of 4–10 repetitions at moderate intensity.

Results: The prevalence of frailty criteria in prefrail and frail older adults were reduced after both LSRT and HSRT. In prefrail, LSRT significantly improved lower-limb muscle strength, while mobility was only improved after HSRT. Muscle power and dual-task performance were significantly increased in both LSRT and HSRT. In frail, LSRT and HSRT similarly improved lower-limb muscle strength and power. However, exclusive improvements in dual-task were observed after LSRT. Memory was significantly increased in prefrail and frail, regardless of the type of resistance training. No significant changes were observed in blood pressure and heart rate.

Conclusion: Findings of the present study indicated that both LSRT and HSRT reversed frailty status and improved physical performance in prefrail and frail older adults. Notably, different patterns of improvement were observed among RT protocols. Regarding frailty status, LSRT seemed to be more effective in reverse prefrailty and frailty when compared to HSRT. Greater improvements in muscle strength and power were also observed after LSRT, while HSRT produced superior increases in mobility and dual-task performance. One-leg stand performance was significantly reduced in LSRT, but not HSRT and CG, after 16 weeks. In contrast, RT programs similarly improved verbal memory in prefrail. Finally, no changes in blood pressure and heart rate were observed, regardless of the type of RT.

Trial Registration: The protocol was approved by the University of Campinas Human Research Ethics Committee (Protocol No. 20021919.7.0000.5404) and retrospectively registered at ClinicalTrials.gov Protocol Registration and Results System: NCT04868071.

Two-Year Follow-up of a Multimodal Intervention on Functional Capacity and Muscle Power in Frail Patients With Type 2 Diabetes

OBJECTIVES

To analyze the effects of a program composed of resistance training and nutritional interventions on functional capacity, maximal strength, and power output after 2 years of follow-up, including 2 periods of 16 weeks of intervention followed by several weeks of intervention cessation in frail patients with type 2 diabetes.

DESIGN

MIDPOW is a substudy of a multicenter, multimodal intervention composed of resistance training combined with a structured diabetes and nutritional education program in frail and prefrail older people with type 2 diabetes (MID-Frail).

SETTING AND PARTICIPANTS

This study recruited 52 participants (mean age: 79 ± 5.6, 63% women), with type 2 diabetes mellitus, frail or prefrail using Fried's frailty phenotype.

METHODS

Primary outcomes of this substudy were Short Physical Performance Battery (SPPB) and maximal power output at 30% and 80% of 1RM.

RESULTS

Each set of 16 weeks of intervention resulted in significant improvements in SPPB performance by a mean of 36.1% at week 18 (P < .001) and 10.2% at week 68 (P < .05). Maximal power output improvements at 30% and 80% of the 1RM ranged from 45.2% to 57.2% at week 18 (P < .01-.001); and no significant changes were observed after the second period of intervention. After 2 years of follow-up, the SPPB and maximal power values observed remained significantly higher than the baseline.

CONCLUSIONS AND IMPLICATIONS

Resistance training combined with nutritional program improved SPPB, maximal strength, and power output in older frail patients with diabetes. These improvements were maintained above the basal levels after several weeks of intervention cessation during a 2-year follow-up.

Differences in Kinetics during One- and Two-Leg Hang Power Clean

The purpose of this study was to quantify the kinetics per leg during the one- and two-leg hang power clean using various loads. Nine male track and field athletes performed the one- and two-leg hang power clean on a force platform. The estimated one-repetition maximum was used for the one-leg hang power clean (OHPC), and the one-repetition maximum was used for the two-leg hang power clean (THPC). The loads used were 30%, 60%, and 90% during both trials. We calculated peak power, peak force, and peak rate of force development during the pull phase from the force-time data. The peak power and the peak force for all loads during the OHPC were statistically greater than during the THPC. The peak rates of force development at 60% and 90% during the OHPC were statistically greater than during the THPC. Additionally, the peak power at 90% was significantly less than at 60% during the THPC. These findings suggest that the OHPC at loads of 60% and 90% is a weightlifting exercise that exhibits greater explosive force and power development characteristics than the THPC.

Effects of Power-Oriented Resistance Training With Heavy vs. Light Loads on Muscle-Tendon Function in Older Adults: A Study Protocol for a Randomized Controlled Trial

Background

Power-oriented resistance training (PRT) is one of the most effective exercise programs to counteract neuromuscular and physical function age-related declines. However, the optimal load that maximizes these outcomes or the load-specific adaptations induced on muscle power determinants remain to be better understood. Furthermore, to investigate whether these adaptations are potentially transferred to an untrained limb (i.e., cross-education phenomenon) could be especially relevant during limb-immobilization frequently observed in older people (e.g., after hip fracture).

Methods

At least 30 well-functioning older participants (>65 years) will participate in a within-person randomized controlled trial. After an 8-week control period, the effects of two 12-week PRT programs using light vs. heavy loads will be compared using an unilateral exercise model through three study arms (light-load PRT vs. non-exercise; heavy-load PRT vs. non-exercise; and light- vs. heavy- load PRT). Muscle-tendon function, muscle excitation and morphology and physical function will be evaluated to analyze the load-specific effects of PRT in older people. Additionally, the effects of PRT will be examined on a non-exercised contralateral limb.

Discussion

Tailored exercise programs are largely demanded given their potentially greater efficiency preventing age-related negative consequences, especially during limb-immobilization. This trial will provide evidence supporting the use of light- or heavy-load PRT on older adults depending on individual needs, improving decision making and exercise program efficacy.

Clinical Trial Registration

NCT03724461 registration data: October 30, 2018.

The Effects of Lateral Bounds on Post-Activation Potentiation of Change-of-Direction Speed Measured by the 505 Test in College-Aged Men and Women

Forty recreationally-trained individuals completed four testing sessions to determine whether lateral bounds (LB) or weighted lateral bounds enhanced change-of-direction (COD) speed measured by the 505 COD speed test. Session 1 included vertical jump and lateral bound (LB) testing to measure power. Sessions 2–4 involved three randomized conditioning activities (CA): 3 × 5 LB; 3 × 5 weighted LB (10% body mass provided by a weighted vest); and a control condition (4-min rest). The 505 COD speed test was performed 5- and 2.5-min pre-CA, and ~15 s, 4, 8, 12, and 16 min post-CA. A 3 × 6 repeated measures analysis of variance (ANOVA) calculated performance changes across time points post-CA. A 3 × 2 repeated measures ANOVA analyzed best potentiated performance. Smallest worthwhile change (SWC) measured within-subject 505 COD speed test performance. Partial correlations controlling for sex calculated relationships between the vertical jump, LB, and percent potentiation. There were no differences (p = 0.919) in 505 time relative to baseline for any CA, nor was the SWC exceeded. The best potentiated 505 time was faster (p < 0.001) than baseline for all CA, with no between-CA differences. There were no significant (p = 0.056–0.993) correlations between power and potentiation. LB and weighted LB did not potentiate the 505 COD speed test, although performance was not hindered.

A High-Intensity Exercise Intervention Improves Older Women Lumbar Spine and Distal Tibia Bone Microstructure and Function: A 20-Week Randomized Controlled Trial

Introduction: The effects of ageing on bone can be mitigated with different types of physical training, such as power training. However, stimuli that combine increasing external and internal loads concomitantly may improve bone quality. The goal of this study was to assess the efficacy of a combined power and plyometric training on lumbar spine and distal tibia microstructure and function. Methods: 38 sedentary elderly women between 60 and 70 years were randomly allocated in experimental (N = 21) and control group (N = 17). The effects of the 20-week protocol on lumbar spine microstructure and tibia microstructure and function were assessed by trabecular bone score (TBS), high resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis. Results: when compared to the effects found in the control group, the experimental group showed significant improvements in lumbar spine TBS (Hedges' g = 0.77); and in distal tibia trabecular thickness (g = 0.82) and trabecular bone mineral density (g=0.63). Conclusion: our findings underscore the effectiveness of the proposed intervention, suggesting it as a new strategy to slow down and even reverse the structural and functional losses in the skeletal system due to ageing.

Is the Optimal Load for Maximal Power Output During Hang Power Cleans Submaximal?

PURPOSE

The optimal load for maximal power output during hang power cleans (HPCs) from a mechanical perspective is the 1-repetition-maximum (1RM) load; however, previous research has reported otherwise. The present study thus aimed to investigate the underlying factors that determine optimal load during HPCs.

METHODS

Eight competitive Olympic weight lifters performed HPCs at 40%, 60%, 70%, 80%, 90%, 95%, and 100% of their 1RM while the ground-reaction force and bar/body kinematics were simultaneously recorded. The success criterion during HPC was set above parallel squat at the receiving position.

RESULTS

Both peak power and relative peak power were maximized at 80% 1RM (3975.7 [439.1] W, 50.4 [6.6] W/kg, respectively). Peak force, force at peak power, and relative values tended to increase with heavier loads (P < .001), while peak system velocity and system velocity at peak power decreased significantly above 80% 1RM (P = .005 and .011, respectively). There were also significant decreases in peak bar velocity (P < .001) and bar displacement (P < .001) toward heavier loads. There was a strong positive correlation between peak bar velocity and bar displacement in 7 of 8 subjects (r > .90, P < .01). The knee joint angle at the receiving position fell below the quarter-squat position above 70% 1RM.

CONCLUSIONS

Submaximal loads were indeed optimal for maximal power output for HPC when the success criterion was set above the parallel-squat position. However, when the success criterion was defined as the quarter-squat position, the optimal load became the 1RM load.

Community-Based Upper Extremity Power Training for Youth with Cerebral Palsy: A Pilot Study

Aim: To examine the effects of an upper-extremity, community-based, and power-training intervention.Methods: Twelve participants with cerebral palsy (CP) [8 males, 4 females; mean age 14 years 6 months (SD 5 years 4 months), range 7-24] were randomly assigned to a rest-training (RT; n = 6) or training-rest (n = 6) group in this randomized, cross-over design. Training took place in participants' home or school, three times per week for 6 weeks. We examined changes in upper extremity average power output (Pavg) in watts (W) and changes in function via the Pediatric Outcomes Data Collection Instrument (PODCI).Results: Each participant completed at least 15 of the 18 total training sessions (91.2% adherence). Pavg increased 92.2% on average among participants (p < .05). There was a significant three-way interaction among treatment, sequence, and period with the data stratified by (Bimanual Fine Motor Function [BFMF]) level on the pain subscale of the PODCI (p = 0.0118). All participants decreased pain after training with the exception of individuals with lower functioning (BFMF II-V) in the RT group.Conclusion: A community-based upper extremity power-training intervention was feasible and effective at improving power among young people with CP and has the potential to improve pain.

Effects of using compound or complex strength-power training during in-season in team sports

Literature is scarce on how players with poorly and well developed physical qualities respond to different combinations of strength-power training during in-season. The aim of this study was to investigate the effects of (i) compound training performed by stronger athletes at different days and (ii) complex training performed by weaker athletes within the same training session. Twenty male handball players were classified as strong or weak according to countermovement jump performance and assigned to a 12-week training programme. Linear sprint, changes of direction, repeated sprint ability and vertical jump capacity were used to assess physical profiles. Compound training performed by stronger players resulted in unclear effects on vertical jump, 20-m and repeated sprint. Likely improvements were found in 10-m sprint (-11.3%; 11.9%). Weaker players who performed complex training presented likely and very likely improvements on vertical jump (13.7%; 5.4%), sprint (10 m, -10.7%; 10.3%; 20 m, -6.0%; 3.4%) and repeated sprint (-4.1%; 3.7%) with moderate to large effect size. The results show that complex and compound strategies are useful in improving the physical profiles of weaker players and maintaining stronger players' capacities during in-season, respectively. Players involved in the same competitive context, even from the same team, may require different strength training strategies.

FLYWHEEL TRAINING IN MUSCULOSKELETAL REHABILITATION: A CLINICAL COMMENTARY

Flywheel training is a relatively new method used to train the human body with continuous resistance and eccentric overload. The performed exercises result in improvements of strength and power, hypertrophy, muscle activation, muscle length, and tendon stiffness. Other positive effects of flywheel training are athletically relevant improvements in things such as speed, jump height and change of direction. The positive results can be explained by the eccentric and power characteristics of the training, making flywheel training ideal for use in musculoskeletal rehabilitation. Flywheel training can be used for injury prevention, training after a period of unloading, tendon and muscle rehabilitation, as part of post-operative rehabilitation, during late stage sport specific rehabilitation as well as for fall prevention and treatment of sarcopenia among elderly. The purpose of this commentary is to inform physical therapists about the use of flywheel training in musculoskeletal rehabilitation.

LEVEL OF EVIDENCE

5.

Correlational Analysis between Joint-level Kinetics of Countermovement Jumps and Weightlifting Derivatives

The purpose of this study was to investigate the mechanical similarity between net joint moments (NJM) of the countermovement jump (CMJ) and the hang power clean (HPC) and jump shrug (JS). Twelve male Lacrosse players performed three maximal effort CMJs and three repetitions of the HPC and JS at 30%, 50%, and 70% of their HPC one repetition maximum (1-RM). Ground reaction forces and motion capture data were used to calculate the NJM of the hip, knee, and ankle joints during each exercise. Statistical comparison of the peak NJM indicated that NJM during the HPC and JS across all loads were equal to or greater than the NJM during the CMJ (all p < 0.025). In addition, correlation analyses indicated that CMJ hip NJM were associated (all p < 0.025) with HPC hip NJM at 30% and 70% (r = 0.611-0.822) and JS hip NJM at 50% and 70% (r = 0.674-0.739), whereas CMJ knee NJM were associated with HPC knee NJM at 70% (r = 0.638) and JS knee NJM at 50% and 70% (r = 0.664-0.732). Further, CMJ ankle NJM were associated with HPC ankle NJM at 30% and 50% (r = 0.615-0.697) and JS ankle NJM at 30%, 50%, and 70% (r = 0.735-0.824). Lastly, knee and ankle NJM during the JS were greater than during the HPC at 30% and 50% of 1-RM (all p < 0.017). The degree of mechanical similarity between the CMJ and the HPC and JS is dependent on the respective load and joint.

Similar Strength and Power Adaptations between Two Different Velocity-Based Training Regimens in Collegiate Female Volleyball Players

This study investigated the effects of two different velocity-based training (VBT) regimens on muscular adaptations. Fifteen female college volleyball players were randomly assigned into either progressive velocity-based training (PVBT) or optimum training load (OTL). Both groups trained three times a week for seven weeks. PVBT performed a 4-week strength block (e.g., 0.55⁻0.70 m·s-1) followed by a 3-week power block (e.g., 0.85⁻1.0 m·s-1), whereas OTL performed training at ~0.85⁻0.9 m·s-1. 1RM and peak power output (PP) assessments on the back squat (BS), bench press (BP) and deadlift (DL) exercises were assessed pre and post training. There was a main time effect (p ≤ 0.05) for BS and BP 1RM, (PVBT: 19.6%, ES: 1.72; OTL: 18.3%, ES: 1.57) and (PVBT: 8.5%, ES: 0.58; OTL: 10.2%, ES: 0.72), respectively. OTL increased DL 1RM to a greater extent than PVBT (p ≤ 0.05), (OTL: 22.9%, ES: 1.49; PVBT: 10.9%, ES: 0.88). Lastly, there was a main time effect (p ≤ 0.05) for BS, BP and DL PP, (PVBT: 18.3%, ES: 0.86; OTL: 19.8%, ES: 0.79); (PVBT: 14.5%, ES: 0.81; OTL: 27.9%, ES: 1.68); (PVBT: 15.7%, ES: 1.32; OTL: 20.1%, ES: 1.77) respectively. Our data suggest that both VBT regimens are effective for improving muscular performance in college volleyball players during the offseason period.

Non-periodized and Daily Undulating Periodized Resistance Training on Blood Pressure of Older Women

The present study aimed at investigating the effects of a daily undulating periodization (DUP) and non-periodized (NP) resistance training programs on hemodynamic parameters of older women. Forty-two older women were randomized into one of the three experimental groups: NP, DUP, and control group (CG). Evaluations of the hemodynamic parameters occurred before, during and after the intervention. The exercise programs were performed twice a week over 22 weeks. NP and DUP groups were based on 3 sets of 8-10 repetitions in 9 exercises. In NP, the two exercise sessions were based on traditional strength training, which was performed at a Difficult intensity according to the rating of perceived exertion (RPE) method. In DUP, the first session was based on power resistance exercise, in which the concentric muscle contraction was performed as fast as possible at a moderate intensity based on RPE, while the second session was the same that was performed by NP. The findings demonstrated that diastolic blood pressure (90.4 vs. 76.2 mmHg) and mean arterial pressure (108.6 vs. 92.7 mmHg) were significantly reduced after NP, while no significant alterations were observed in DUP. Nevertheless, both training groups seem to have a cardio protective effect, since both training modes prevented the increase in HR reported in the experimental period in CG. In conclusion, our findings indicate that a 22-week NP resistance training program causes beneficial effects on hemodynamic parameters of older women. Trial Registration: NCT03443375.

Optimum Power Loads for Elite Boxers: Case Study with the Brazilian National Olympic Team

The purpose of this case study was to examine the effects of a resistance-training program based on the optimum power loads (OPL) method on neuromuscular performance of Olympic boxing athletes during preparation for the Rio-2016 Olympic Games. Twelve elite amateur boxers from the Brazilian National Olympic Team participated in this study. Athletes were assessed at four time-points, over two consecutive competitive seasons. In the first season (considered as "control period"), the athletes executed a non-controlled strength-power training program for 10 weeks. In the second season (a seven-week experimental period), the elite boxers performed 14 power-oriented training sessions, comprising bench press (BP) and jump squat (JS) exercises at the OPL. Maximum bar-power output in BP and JS exercises was measured pre and post both training phases. Magnitude-based inferences were used to compare changes in pre and post training tests. Bar-power outputs increased meaningfully in both BP (+8%) and JS (+7%) exercises after the OPL training program. In contrast, after the control period, no worthwhile improvements were observed in the variables tested. Based on the findings of this study, highly trained boxers might benefit from the use of a training scheme based on OPL.

The Effect of Short-Term Sport-Specific Strength and Conditioning Training on Physical Fitness of Well-Trained Mixed Martial Arts Athletes

The purpose of the present study was to investigate the effect of a short-term, high-intensity, low-volume Mixed Martial Arts (MMA) specific strength and conditioning training program on performance in national level MMA athletes. Seventeen experienced fighters were divided into two groups: (A) Specific Training Group (STG; n = 10), which followed a specific strength and conditioning program designed according to the demands of MMA competition and (B) Regular Training Group (RTG; n = 7), in which participants followed a regular strength and conditioning program commonly used by MMA athletes. Before and after the four-week training period (3 days per week), body composition, aerobic fitness, strength, power and speed were evaluated. Significant improvements in estimated VO2max, average power during the 2000 m rowing, bench press, back squat and deadlift 1RM, SJ power, CMJ height power, medicine ball throw velocity, 10 m sprint and 2 m take down speed and fat-free mass were found only in the STG (3.7 to 22.2%; p < 0.05; Hedge's g = -0.42 - 4.1). No significant changes were found for the RTG (p = 0.225 to 0.811). Significant differences between the groups were found for almost all post-training assessments (p < 0.05; Hedge's g = 0.25 - 1.45) as well as for the percentage changes from pre to post training (p < 0.05; Hedge's g: 0.25 - 1.45). Significant relationships were found between percentage changes in fat-free mass, endurance capacity, muscle strength/power and speed (r: -0.475 to 0.758; p < 0.05). These results suggest that a high-intensity low-volume strength and conditioning training intervention designed according to the demands of MMA competition may result in significant performance improvements for well-trained fighters.

Comparison of the acute effects of traditional versus high velocity resistance training on metabolic, cardiovascular, and psychophysiological responses in elderly hypertensive women

Objectives

The aim of the present study was to compare the acute effects of traditional resistance training (RT) versus high velocity RT (HVRT) on metabolic, cardiovascular, and psychophysiological responses in elderly hypertensive women.

Methods

Fifteen elderly women (mean age ± standard deviation, 67.1±6.9 years) classified as having hypertension stage 1 or 2 were randomly allocated to complete traditional RT or HVRT; 1 week later, subjects allocated to RT completed the HVRT session and vice-versa. Heart rate, blood pressure, affective response, perceived effort, and blood samples analyzing lactate, nitrate, nitrite, oxidative damage (thiobarbituric acid reactive substances [TBARS]), and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid equivalent antioxidant capacity (TEAC) collected before and after training sessions were assessed. Nutritional counseling was provided regarding nutrients that could affect cardiovascular and nitrate/nitrite analysis.

Results

Systolic blood pressure was not statistically different (p>0.05) between conditions at the beginning and during 30 minutes after sessions. Diastolic blood pressure, rate pressure product, and heart rate were not statistically different (p>0.05) between conditions at the beginning and during 45 minutes after sessions. Nitric oxide was significantly higher (p<0.0005) for HVRT compared to RT after 30 minutes of exercise. TBARS and TEAC were significantly higher (p<0.05) for HVRT compared with RT only immediately after exercise. There were no differences for psychophysiological variables between protocols.

Conclusion

The acute cardiovascular and metabolic responses, including oxidative stress, are transient and within normal values. Taken together with the positive affective responses, both HVRT and RT with this intensity and volume seem to be safe for elderly hypertensive women under medication.

Intermittent Resistance Training at Moderate Altitude: Effects on the Force-Velocity Relationship, Isometric Strength and Muscle Architecture

Intermittent hypoxic resistance training (IHRT) may help to maximize the adaptations following resistance training, although conflicting evidence is available. The aim of this study was to explore the influence of moderate altitude on the functional, neural and muscle architecture responses of the quadriceps muscles following a power-oriented IHRT intervention. Twenty-four active males completed two 4-week consecutive training blocks comprising general strengthening exercises (weeks 1–4) and power-oriented resistance training (weeks 5–8). Training sessions were conducted twice a week at moderate altitude (2320 m; IHRT, n = 13) or normoxia (690 m; NT, n = 11). Training intensity during the second training block was set to the individual load corresponding to a barbell mean propulsive velocity of 1 m·s⁻¹. Pre-post assessments, performed under normoxic conditions, comprised quadriceps muscle architecture (thickness, pennation angle and fascicle length), isometric maximal (MVF) and explosive strength, and voluntary muscle activation. Dynamic strength performance was assessed through the force-velocity relationship (F₀, V₀, P₀) and a repeated CMJ test (CMJ_15MP). Region-specific muscle thickness changes were observed in both training groups (p < 0.001, ηG2 = 0.02). A small opposite trend in pennation angle changes was observed (ES [90% CI]: −0.33 [−0.65, −0.01] vs. 0.11 [−0.44, 0.6], in the IHRT and NT group, respectively; p = 0.094, ηG2 = 0.02). Both training groups showed similar improvements in MVF (ES: 0.38 [0.20, 0.56] vs. 0.55 [0.29, 0.80], in the IHRT and NT group, respectively; p = 0.645, ηG2 < 0.01), F₀ (ES: 0.41 [−0.03, 0.85] vs. 0.52 [0.04, 0.99], in the IHRT and NT group, respectively; p = 0.569, ηG2 < 0.01) and P₀ (ES: 0.53 [0.07, 0.98] vs. 0.19 [−0.06, 0.44], in the IHRT and NT group, respectively; p = 0.320, ηG2 < 0.01). No meaningful changes in explosive strength performance were observed. In conclusion, contrary to earlier adverse associations between altitude and resistance-training muscle adaptations, similar anatomical and functional muscle strength responses can be achieved in both environmental conditions. The observed region-specific muscle thickness changes may encourage further research on the potential influence of IHRT on muscle morphological changes.

A 4-Week Intervention Involving Mobile-Based Daily 6-Minute Micro-Sessions of Functional High-Intensity Circuit Training Improves Strength and Quality of Life, but Not Cardio-Respiratory Fitness of Young Untrained Adults

The present study was designed to assess the psycho-physiological responses of physically untrained individuals to mobile-based multi-stimulating, circuit-like, multiple-joint conditioning (Circuit_HIIT) performed either once (1xCircuit_HIIT) or twice (2xCircuit_HIIT) daily for 4 weeks. In this single-center, two-arm randomized, controlled study, 24 men and women (age: 25 ± 5 years) first received no training instructions for 4 weeks and then performed 4 weeks of either 1xCircuit_HIIT or 2xCircuit_HIIT (5 men and 7 women in each group) daily. The 1xCircuit_HIIT and 2xCircuit_HIIT participants carried out 90.7 and 85.7% of all planned training sessions, respectively, with average heart rates during the 6-min sessions of 74.3 and 70.8% of maximal heart rate. Body, fat and fat-free mass, and metabolic rate at rest did not differ between the groups or between time-points of measurement. Heart rate while running at 6 km⋅h^-1 declined after the intervention in both groups. Submaximal and peak oxygen uptake, the respiratory exchange ratio and heart rate recovery were not altered by either intervention. The maximal numbers of push-ups, leg-levers, burpees, 45°-one-legged squats and 30-s skipping, as well as perception of general health improved in both groups. Our 1xCircuit_HIIT or 2xCircuit_HIIT interventions improved certain parameters of functional strength and certain dimensions of quality of life in young untrained individuals. However, they were not sufficient to enhance cardio-respiratory fitness, in particular peak oxygen uptake.

The perceived feasibility and acceptability of a conceptually challenging exercise training program in older adults

BACKGROUND

Exercise training is an essential component of falls prevention strategies, but they do not fully address components of physical function that leads to falls. The training approaches to achieve this may not be perceived as appropriate or even feasible in older adults. This study aims to assess the perceived feasibility and acceptability of novel exercise training approaches not usually prescribed to older adults.

PATIENTS AND METHODS

Fourteen adults were exposed to conceptually and physically demanding exercises. Interviews were then conducted to determine perceptions and acceptability of individual exercise tasks. Qualitative thematic analysis was used to identify themes.

RESULTS

Safety and confidence, acceptability, and population participation were the key themes identified. Staff knowledge, presence, program design, and overt safety equipment were important for alleviating initial apprehension. Although physically demanding, participants expressed satisfaction when challenged. Prior disposition, understanding the value, and the appeal of novel exercises were perceived to influence program engagement.

CONCLUSION

Given the evidence for acceptability, this type of training is feasible and may be appropriate as part of an exercise training program for older adults. Further research should be conducted to confirm that the physical adaptations to exercise training approaches as presented in this study occur in a similar manner to that observed in younger adults, and to also determine whether these adaptations lead to prolonged independence and reduced falls in older adults compared to usual care.

Effects of Pomegranate Juice Supplementation on Oxidative Stress Biomarkers Following Weightlifting Exercise

The aim of this study was to test the hypothesis that pomegranate juice supplementation would blunt acute and delayed oxidative stress responses after a weightlifting training session. Nine elite weightlifters (21.0 ± 1 years) performed two Olympic-Weightlifting sessions after ingesting either the placebo or pomegranate juice supplements. Venous blood samples were collected at rest and 3 min and 48 h after each session. Compared to the placebo condition, pomegranate juice supplementation attenuated the increase in malondialdehyde (−12.5%; p < 0.01) and enhanced the enzymatic (+8.6% for catalase and +6.8% for glutathione peroxidase; p < 0.05) and non-enzymatic (+12.6% for uric acid and +5.7% for total bilirubin; p < 0.01) antioxidant responses shortly (3 min) after completion of the training session. Additionally, during the 48 h recovery period, pomegranate juice supplementation accelerated (p < 0.05) the recovery kinetics of the malondialdehyde (5.6%) and the enzymatic antioxidant defenses compared to the placebo condition (9 to 10%). In conclusion, supplementation with pomegranate juice has the potential to attenuate oxidative stress by enhancing antioxidant responses assessed acutely and up to 48 h following an intensive weightlifting training session. Therefore, elite weightlifters might benefit from blunted oxidative stress responses following intensive weightlifting sessions, which could have implications for recovery between training sessions.

Acute effects of power and resistance exercises on hemodynamic measurements of older women

Purpose

The purpose of this study was to compare the acute effects of resistance training (RT) and power training (PT) on the hemodynamic parameters and nitric oxide (NO) bioavailability of older women.

Materials and methods

A randomized experimental design was used in this study. Twenty-one older women (age: 67.1±4.6 years; body mass index: 28.03±4.9 kg/m²; systolic blood pressure: 135.1±21.1 mmHg) were recruited to participate in this study. Volunteers were randomly allocated into PT, RT, and control session (CS) groups. The PT and RT groups underwent a single session of physical exercise equalized by training volume, characterized by 3 sets of 8–10 repetitions in 8 different exercises. However, RT group performed exercise at a higher intensity (difficult) than PT (moderate) group. On the other hand, concentric contractions were faster in PT group than in RT group. Hemodynamic parameters and saliva samples (for NO quantification) were collected before and during an hour after exercise completion.

Results

Results demonstrated post-exercise hypotension during 35 minutes in the PT when compared to rest period (P=0.001). In turn, RT showed decreased heart rate and double product (P<0.001) during the whole evaluation period after exercise completion compared with the rest period. NO levels increased in the PT and RT during the whole evaluation period in relation to rest period. However, there were no differences between PT, RT, and CS regarding hemodynamic and NO evaluations.

Conclusion

Data indicate that an acute session of power and resistance exercise can be effective to cause beneficial changes on hemodynamic parameters and NO levels in older women.

POWER training in chronic stroke individuals: differences between responders and nonresponders

BACKGROUND

Lower extremity muscle weakness is a primary contributor to post-stroke dysfunction. Resistance training is an effective treatment for hemiparetic weakness and improves walking performance. Post-stroke subject characteristics that do or do not improve walking speed following resistance training are unknown.

OBJECTIVE

The purpose of this paper was to describe baseline characteristics, as well as responses to training, associated with achieving a minimal clinically important difference (MCID) in walking speed (≥0.16 m/s) following Post-stroke Optimization of Walking Using Explosive Resistance (POWER) training.

METHODS

Seventeen participants completed 24 sessions of POWER training, which included intensive progressive leg presses, jump training, calf raises, sit-to-stands, step-ups, and over ground fast walking. Outcomes included SSWS, FCWS, DGI, FMA-LE, 6-MWT, paretic knee power, non-paretic knee power, and paretic step ratio.

RESULTS

Specific to those who reached MCID in SSWS (e.g. "responders"), significant improvements in SSWS, FCWS, 6-MWT, paretic knee power, and non-paretic knee power was realized. Paretic knee power and non-paretic knee power significantly improved in those who did not achieve MCID for gait speed (e.g. "non-responders").

CONCLUSION

The potential for POWER training to enhance general locomotor function was confirmed. Baseline paretic knee strength/power may be an important factor in how an individual responds to this style of training. The lack of change within the non-responders emphasizes the contribution of factors other than lower extremity muscle power improvement to locomotor dysfunction.

Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women

The effects of circuit-like functional high-intensity training (Circuit_HIIT) alone or in combination with high-volume low-intensity exercise (Circuit_combined) on selected cardio-respiratory and metabolic parameters, body composition, functional strength and the quality of life of overweight women were compared. In this single-center, two-armed randomized, controlled study, overweight women performed 9-weeks (3 sessions·wk⁻¹) of either Circuit_HIIT (n = 11), or Circuit_combined (n = 8). Peak oxygen uptake and perception of physical pain were increased to a greater extent (p < 0.05) by Circuit_HIIT, whereas Circuit_combined improved perception of general health more (p < 0.05). Both interventions lowered body mass, body-mass-index, waist-to-hip ratio, fat mass, and enhanced fat-free mass; decreased ratings of perceived exertion during submaximal treadmill running; improved the numbers of push-ups, burpees, one-legged squats, and 30-s skipping performed, as well as the height of counter-movement jumps; and improved physical and social functioning, role of physical limitations, vitality, role of emotional limitations, and mental health to a similar extent (all p < 0.05). Either forms of these multi-stimulating, circuit-like, multiple-joint training can be employed to improve body composition, selected variables of functional strength, and certain dimensions of quality of life in overweight women. However, Circuit_HIIT improves peak oxygen uptake to a greater extent, but with more perception of pain, whereas Circuit_combined results in better perception of general health.

Bar velocities capable of optimising the muscle power in strength-power exercises

This study aimed at testing whether there are mean propulsive velocities (MPVs) capable of maximising the mean propulsive power (MPP) during the execution of bench press (BP), bench throw (BT), half squat (HS) and jump squat (JS). Additionally, we assessed the differences in MPP/MPV between ballistic and traditional exercises. Seventeen male rugby sevens players performed MPP tests in BP, BT, HS and JS and maximum isometric force (MIF) tests in HS and BP. The JS presented higher MPP (977.4 ± 156.2 W) than the HS (897.9 ± 157.7 W) (P < 0.05); the BP (743.4 ± 100.1 W) presented higher MPP than the BT (697.8 ± 70.4 W) (P < 0.05). Ballistic exercises presented higher optimum MPV (JS = 1.02 ± 0.07 m·s^-1; BT = 1.67 ± 0.15 m·s^-1) than traditional exercises (HS = 0.93 ± 0.08 m·s^-1; BP = 1.40 ± 0.13 m·s^-1) (P < 0.05). The optimum MPP in the JS, BT, HS and BP occurred at 28.2 ± 5.79, 23.3 ± 4.24, 32.4 ± 9.46 and 27.7 ± 5.33% of the MIF, respectively. The coefficient of variation (CV) of MPV at optimum MPP ranged from 7.4% to 9.7%, while the CV of %MIF ranged from 18.2% to 29.2%. The MPV is a more precise indicator of the optimum loads than the percentages of MIF due to its low inter-subject variability as expressed by CV. Therefore, MPV can be used to determine the optimum power load in the four investigated exercises.

The Effect of the Number of Sets on Power Output for Different Loads

There is much debate concerning the optimal load (OL) for power training. The purpose of this study was to investigate the effect of the number of sets performed for a given load on mean power output (P_mean). Fourteen physically active men performed 3 sets of 3 bench-press repetitions with 30, 40 and 50 kg. The highest mean power value (P_max) across all loads and P_mean were compared when data were taken from the first set at each absolute load vs. from the best of three sets performed. P_mean increased from the first to the third set (from 5.99 ± 0.81 to 6.16 ± 0.96 W·kg⁻¹, p = 0.017), resulting in a main effect of the set number (p < 0.05). At the 30 kg load P_mean increased from the first to the third set (from 6.01 ± 0.75 to 6.35 ± 0.85 W·kg⁻¹; p < 0.01). No significant effect was observed at 40 and 50 kg loads (p > 0.05). P_max and velocity were significantly affected by the method employed to determine P_mean at each load (p < 0.05). These results show a positive effect of the number of sets per load on P_mean, affecting P_max, OL and potentially power training prescription.

Neuromuscular and blood lactate responses to squat power training with different rest intervals between sets

Studies investigating the effect of rest interval length (RI) between sets on neuromuscular performance and metabolic response during power training are scarce. Therefore, the purpose of this study was to compare maximal power output, muscular activity and blood lactate concentration following 1, 2 or 3 minutes RI between sets during a squat power training protocol. Twelve resistance-trained men (22.7 ± 3.2 years; 1.79 ± 0.08 cm; 81.8 ± 11.3 kg) performed 6 sets of 6 repetitions of squat exercise at 60% of their 1 repetition maximum. Peak and average power were obtained for each repetition and set using a linear position transducer. Muscular activity and blood lactate were measured pre and post-exercise session. There was no significant difference between RI on peak power and average power. However, peak power decreased 5.6%, 1.9%, and 5.9% after 6 sets using 1, 2 and 3 minutes of RI, respectively. Average power also decreased 10.5% (1 min), 2.6% (2 min), and 4.3% (3 min) after 6 sets. Blood lactate increased similarly during the three training sessions (1-min: 5.5 mMol, 2-min: 4.3 mMol, and 3-min: 4.0 mMol) and no significant changes were observed in the muscle activity after multiple sets, independent of RI length (pooled ES for 1-min: 0.47, 2-min: 0.65, and 3-min: 1.39). From a practical point of view, the results suggest that 1 to 2 minute of RI between sets during squat exercise may be sufficient to recover power output in a designed power training protocol. However, if training duration is malleable, we recommend 2 min of RI for optimal recovery and power output maintenance during the subsequent exercise sets. Key pointsThis study demonstrates that 1 minute of RI between sets is sufficient to maintain maximal power output during multiple sets of a power-based exercise when it is composed of few repetitions and the sets are not performed until failure. Therefore, a short RI should be considered when designing training programs for the development of muscular power.Short RI may be more practical for strength coaches under time constraints (i.e. 1 minute of RI required only 7 minutes to complete an exercise session, while with 2 minutes take 12 minutes, and 17 minutes with 3 minutes of RI).Future research is needed to examine the longitudinal effects of interval rest in training programs designed for the development of muscular power.

OGT and OGA expression in postmenopausal skeletal muscle associates with hormone replacement therapy and muscle cross-sectional area

Protein glycosylation via O-linked N-acetylglucosaminylation (O-GlcNAcylation) is an important post-translational regulatory mechanism mediated by O-GlcNAc transferase (OGT) and responsive to nutrients and stress. OGT attaches an O-GlcNAc moiety to proteins, while O-GlcNAcase (OGA) catalyzes O-GlcNAc removal. In skeletal muscle of experimental animals, prolonged increase in O-GlcNAcylation associates with age and muscle atrophy. Here we examined the effects of hormone replacement therapy (HRT) and power training (PT) on muscle OGT and OGA gene expression in postmenopausal women generally prone to age-related muscle weakness. In addition, the associations of OGT and OGA gene expressions with muscle phenotype were analyzed. Twenty-seven 50-57-year-old women participated in a yearlong randomized placebo-controlled trial: HRT (n=10), PT (n=8) and control (n=9). OGT and OGA mRNA levels were measured from muscle samples obtained at baseline and after one year. Knee extensor muscle cross-sectional area (CSA), knee extension force, running speed and vertical jumping height were measured. During the yearlong intervention, HRT suppressed the aging-associated upregulation of OGT mRNA that occurred in the controls. The effects of PT were similar but weaker. HRT also tended to increase the OGA mRNA level compared to the controls. The change in the ratio of OGT to OGA gene expressions correlated negatively with the change in muscle CSA. Our results suggest that OGT and OGA gene expressions are associated with muscle size during the critical postmenopausal period. HRT and PT influence muscle OGT and OGA gene expression, which may be one of the mechanisms by which HRT and PT prevent aging-related loss of muscle mass.

Postactivation potentiation: an introduction

Improving strength and power in the athlete who is being rehabilitated is a central focus of the sports physical therapist, particularly in the terminal phases of rehabilitation where the emphasis shifts to readiness to return to sport and sports performance enhancement. High load strength training and power training through plyometric exercises are two key components of performance enhancement programs. A current concept in the strength and conditioning literature that is relatively unknown in sports physical therapy is postactivation potentiation (PAP). Even though we have limited data and there may be limited application of the concept of PAP for the sports physical therapist, awareness of this phenomenon is important nonetheless. The purpose of this clinical commentary is to introduce the sports physical therapist to the concept of PAP.

Incorporating kettlebells into a lower extremity sports rehabilitation program

The primary goal of a sports rehabilitation program is to return the injured athlete back to competition as quickly and as safely as possible. Sports physical therapists utilize a variety of exercise equipment to help an athlete restore function after an injury. An injured athlete's therapeutic exercise program frequently includes the prescription of functional strengthening and power exercises during the later stages of rehabilitation. One piece of exercise equipment, the kettlebell, has gained popularity for its ability to allow the user to perform functional power exercises. The unique exercises that can be performed with kettlebells may have utility in sports physical therapy practice. This clinical suggestion outlines the clinical rationale for the inclusion of kettlebell exercises when rehabilitating an athlete with a lower extremity injury.

Power training and postmenopausal hormone therapy affect transcriptional control of specific co-regulated gene clusters in skeletal muscle

At the moment, there is no clear molecular explanation for the steeper decline in muscle performance after menopause or the mechanisms of counteractive treatments. The goal of this genome-wide study was to identify the genes and gene clusters through which power training (PT) comprising jumping activities or estrogen containing hormone replacement therapy (HRT) may affect skeletal muscle properties after menopause. We used musculus vastus lateralis samples from early stage postmenopausal (50-57 years old) women participating in a yearlong randomized double-blind placebo-controlled trial with PT and HRT interventions. Using microarray platform with over 24,000 probes, we identified 665 differentially expressed genes. The hierarchical clustering method was used to assort the genes. Additionally, enrichment analysis of gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was carried out to clarify whether assorted gene clusters are enriched with particular functional categories. The analysis revealed transcriptional regulation of 49 GO/KEGG categories. PT upregulated transcription in "response to contraction"-category revealing novel candidate genes for contraction-related regulation of muscle function while HRT upregulated gene expression related to functionality of mitochondria. Moreover, several functional categories tightly related to muscle energy metabolism, development, and function were affected regardless of the treatment. Our results emphasize that during the early stages of the postmenopause, muscle properties are under transcriptional modulation, which both PT and HRT partially counteract leading to preservation of muscle power and potentially reducing the risk for aging-related muscle weakness. More specifically, PT and HRT may function through improving energy metabolism, response to contraction as well as by preserving functionality of the mitochondria.