Leg Press Strength Research Articles

The Effect of Blood Flow Restriction Exercise Prior to Total Knee Arthroplasty on Postoperative Physical Function, Lower Limb Strength and Patient-Reported Outcomes: ARandomized Controlled Trial.

30-s sit to stand (30STS). Timed Up&Go, 40-m walk test (40mWT), knee range of motion (ROM) 1-repetition maximum (1RM) leg press and knee extensor strength, maximal isometric contraction (MVIC) for the knee extensors and flexors, Knee injury and Osteoarthritis Outcome Score (KOOS), and Euroqol 5-dimensions (EQ-5D-L5) questionnaire. Data were collected at baseline (12 weeks pre-surgery), ~3 days pre-surgery, 3 and 12 months postoperatively. Intention-to-treat analysis revealed no significant between-group differences in the change from baseline to 3 and 12 months postoperatively on 30STS, TUG, or 40mFWT. Significant between-group differences were observed at 3 but not 12 months postoperatively for the corresponding changes in 1RM leg press strength, 1RM knee extensor strength, and MVIC knee extensor favoring BFR-RT. No between-group differences were observed for the delta changes from baseline in knee ROM, KOOS subscales or EQ-5D-L5 at any postoperative time points. These findings suggest that preoperative BFR-RT offered no superior effects compared with usual preoperative care on postoperative physical function or patient-reported outcomes. Preoperative BFR-RT produced amplified gains in lower limb muscle strength at 3 months postoperatively. NCT04081493.

Association between changes in lean mass, muscle strength, endurance, and power following resistance or concurrent training with differing high protein diets in resistance-trained young males.

We assessed the relationship of changes in upper and lower body lean mass with muscle strength, endurance and power responses following two high protein diets (1.6 or 3.2 g.kg-1.d-1) during 16 weeks of either concurrent training (CT) or resistance training (RT) in resistance-trained young males. Forty-eight resistance-trained young males (age: 26 ± 6 yr., body mass index: 25.6 ± 2.9 kg.m-2) performed 16 weeks (four sessions·wk.-1) of CT or RT with either 1.6 g.kg-1.d-1 protein (CT + 1.6; n = 12; RT + 1.6; n = 12) or 3.2 g.kg-1.d-1 protein (CT + 3.2; n = 12; RT + 3.2; n = 12). Relationships between upper (left arm + right arm + trunk lean mass) and lower body (left leg + right leg lean mass) lean mass changes with changes in muscle performance were assessed using Pearson's correlation coefficients. For upper body, non-significant weak positive relationships were observed between change in upper body lean mass and change in pull-up (r = 0.183, p = 0.234), absolute chest press strength (r = 0.159, p = 0.302), chest press endurance (r = 0.041, p = 0.792), and relative chest press strength (r = 0.097, p = 0.529) while non-significant weak negative relationships were observed for changes in absolute upper body power (r = -0.236, p = 0.123) and relative upper body power (r = -0.203, p = 0.185). For lower body, non-significant weak positive relationships were observed between the change in lower body lean mass with change in vertical jump (r = 0.145, p = 0.346), absolute lower body power (r = 0.109, p = 0.480), absolute leg press strength (r = 0.073, p = 0.638), leg press endurance (r < 0.001, p = 0.998), relative leg press strength (r = 0.089, p = 0.564), and relative lower body power (r = 0.150, p = 0.332). Changes in muscle strength, endurance and power adaptation responses following 16 weeks of either CT or RT with different high protein intakes were not associated with changes in lean mass in resistance-trained young males. These findings indicate that muscle hypertrophy has a small, or negligible, contributory role in promoting functional adaptations with RT or CT, at least over a 16-week period.

An Individual vs Parent Supported Physical Activity Intervention in Adolescents with Intellectual Disabilities.

Moderate-to-vigorous physical activity (MVPA) is inadequate in adolescents with intellectual and developmental disabilities (IDD). This report describes the results of an 18-mo. clinical trial in adolescents with IDD which compared changes in accelerometer assessed daily MVPA, gross motor quotient and leg press strength between participants randomized to an exercise intervention delivered to adolescents only (AO) or to the adolescent and a parent (A + P). The 18-mo. trial included a 6-mo. active intervention, 6-mo. maintenance interventions, and a 6-mo. no-contact follow-up. Adolescents in both arms were asked to attend 40 min. remotely delivered group video exercise sessions (0-6 mos. =3 sessions·wk-1., 7-12 mos. =1 session·wk-1). In the A + P arm, one parent/guardian was asked to attend all group remote video exercise sessions and a monthly remotely delivered 30-min. educations/support session with their adolescent across the 12-mo. intervention. Adolescents (n = 116) with IDD (age ~ 16 yrs., 52% female) were randomized to the AO (n = 59) or A + P (n = 57) arms. Mixed modeling, controlling for baseline MVPA and season, indicated minimal but statistically significant changes in MVPA across 6 (p = 0.006), 12 (p < 0.001), and 18 mos. (p < 0.001). However, the change in MVPA in the two intervention arms did not differ significantly at any time point (all p > 0.05). Similarly, gross motor quotient and leg press strength improved significantly over time (p < 0.001) and these changes did not differ between intervention arms (all p > 0.05). Parental involvement had no impact on changes in daily MVPA, gross motor quotient or leg press strength in response to a remotely delivered exercise intervention in adolescents with IDD.

The Effects of Bilateral and Unilateral Training on Leg Press Strength and Vertical Jump Height

This investigation assessed the effects of bilateral and unilateral strength training on strength and power development, as measured by uni- and bi-lateral 3-repetition maximum leg press and vertical jump tests, respectively. 14 college-aged participants were randomized into either bilateral or unilateral training conditions. The participants engaged in biweekly strength training sessions for a period of 4 weeks, with strength and power pre- and post-testing in the weeks immediately before and after the training protocol, respectively. There was no significant (F = 0.98, p = 0.33) main effect of condition for vertical jump height. There was no significant (F = 2.48, p = 0.13) main effect of condition for 1RM bilateral strength. There was no significant (F = 1.86, p = 0.19) main effect of condition for 1RM unilateral strength between both right and left legs. While our investigation yielded no significant results, there may be reason to further investigate this area of research, due to professionals wanting to develop weight training protocols for the athletic and/or injured populations to facilitate greater improvements in performance and/or quicker recovery from injuries.

A Genotype-Phenotype Model for Predicting Resistance Training Effects on Leg Press Performance.

This study develops a comprehensive genotype-phenotype model for predicting the effects of resistance training on leg press performance. A cohort of physically inactive adults (N=193) underwent 12 weeks of resistance training, and measurements of maximum isokinetic leg press peak force, muscle mass, and thickness were taken before and after the intervention. Whole-genome genotyping was performed, and genome-wide association analysis identified 85 novel SNPs significantly associated with changes in leg press strength after training. A prediction model was constructed using stepwise linear regression, incorporating seven lead SNPs that explained 40.4% of the training effect variance. The polygenic score showed a significant positive correlation with changes in leg press strength. By integrating genomic markers and phenotypic indicators, the comprehensive prediction model explained 75.4% of the variance in the training effect. Additionally, five SNPs were found to potentially impact muscle contraction, metabolism, growth, and development through their association with REACTOME pathways. Individual responses to resistance training varied, with changes in leg press strength ranging from -55.83% to 151.20%. The study highlights the importance of genetic factors in predicting training outcomes and provides insights into the potential biological functions underlying resistance training effects. The comprehensive model offers valuable guidance for personalized fitness programs based on individual genetic profiles and phenotypic characteristics.

Changes in strength-related outcomes following velocity-monitored resistance training with 10 % and 20 % velocity loss in older adults

We compared the effects of velocity-monitored resistance training with an intra-set velocity loss (i.e., the decrement in repetition velocity over the set) of 10 % vs. 20 % on strength-related outcomes in older adults. We randomly assigned eighteen older adults to a velocity loss group of 10 % (n = 10; 78 ± 12 years) or 20 % (n = 8; 73 ± 10 years) to perform a 10-week training program. The primary outcomes were the one-repetition maximum (1RM) and the average mean velocity against absolute loads associated with loads <60 % 1RM (MVlow) and ≥ 60 % 1RM (MVhigh) in the leg and chest press exercises, assessed at pre-, mid- (week 5), and post-test. Secondary outcomes included handgrip strength, 1-kg medicine ball throw distance, 10-m walking time, and five-repetition sit-to-stand time. No differences between groups were found in any outcome at any time (p > 0.05). Both groups improved the 1RM leg press from pre- to mid- and post-test and the MVlow and MVhigh from pre- to mid-test (p < 0.05). No group improved the 1RM chest press (p > 0.05), but both increased the MVlow from pre- to mid-test (p < 0.05). Furthermore, both groups improved the sit-to-stand time, while only the 20 % velocity loss group significantly improved handgrip strength and 10-m walking time (p < 0.05). The results showed that both velocity losses improved leg press strength and velocity, chest press velocity, and sit-to-stand time in older adults, although a 10 % velocity loss was more efficient as it required less volume (i.e., total repetitions) than 20 %. Nevertheless, the latter seems required to optimize handgrip strength and 10-m walking time in older people.

Effects of a remotely supervised resistance training program on muscle strength and body composition in adults with cystic fibrosis: Randomized controlled trial

AbstractIntroductionAmong the limited studies on physical exercise interventions in adults with cystic fibrosis (CF), few have specifically addressed the improvement of peripheral muscle strength and body fat‐free mass. The aim of this study was to examine the impacts of a remotely supervised, individualized 8‐week resistance training program of moderate to high intensity on strength and body composition in these subjects.MethodsThis was a randomized controlled trial performed in adults with CF. The exercise group (EX) performed three 1‐h resistance training sessions per week over 8 weeks. The control group (CON) followed the physical activity recommendations of their physician. The main outcomes were muscle strength and body composition, with secondary measures including pulmonary function and quality of life. Two‐way repeated measures analysis was used.ResultsIn 23 participants (age 32.13 ± 7.72 years), the intervention showed a significant beneficial effect on leg press strength, with a large effect size, both in absolute (p = 0.011; = 0.281) and relative (p = 0.007; = 0.310) terms. Large intervention effects were observed on total fat mass (p &lt; 0.001; = 0.415), body adiposity index (p &lt; 0.001; = 0.436), and fat mass index (p &lt; 0.001; = 0.445), all showing reduction in the EX group. In addition, significant large size effects were detected on total fat‐free mass (p = 0.046; = 0.177), trunk fat‐free mass (p = 0.039; = 0.188), and fat‐free mass index (p = 0.048; = 0.174), all favoring exercise. No significant effects were observed on pulmonary function and quality of life.ConclusionsAn 8‐week remotely supervised resistance training program, with moderate to high intensity, effectively improved lower limb muscle strength and body composition.

Effects of Timing and Types of Protein Supplementation on Improving Muscle Mass, Strength, and Physical Performance in Adults Undergoing Resistance Training: A Network Meta-Analysis.

Precise protein supplementation strategies for muscle improvement are still lacking. The timing or type of protein supplementation has been debated as a window of opportunity to improve muscle mass, strength, and physical performance. We conducted a network meta-analysis of randomized controlled trials with protein supplements and resistance training. PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases were searched until May 1, 2023. We included 116 eligible trials with 4,711 participants that reported on 11 timing and 14 types of protein supplementation. Compared with placebo, protein supplementation after exercise (mean difference [MD]: 0.54kg [95% confidence intervals 0.10, 0.99] for fat-free mass, MD: 0.34kg [95% confidence intervals 0.10, 0.58] for skeletal muscle mass) and at night (MD: 2.85kg [0.49, 5.22] for handgrip strength, MD: 12.12kg [3.26, 20.99] for leg press strength) was most effective in improving muscle mass and strength, respectively (moderate certainty). Milk proteins (milk, whey protein, yogurt, casein, and bovine colostrum), red meat, and mixed protein were effective for gains in both muscle mass and strength (moderate certainty). No timing or type of protein showed a significant enhancement in physical performance (timed up-to-go test, 6-min walk test, and gait speed). Pre/postexercise and Night are key recommended times of protein intake to increase muscle mass and strength, respectively. Milk proteins are the preferred types of protein supplements for improving muscle mass and strength. Future randomized controlled trials that directly compare the effects of protein timing or types are needed. This trial was registered at International Prospective Register of Systematic Reviews as CRD42022358766.

Effects of blood-flow restricted exercise versus conventional resistance training in musculoskeletal disorders—a systematic review and meta-analysis

ObjectiveTo compare the effect of low-load blood flow restricted resistance training (BFR-RT) versus high-load resistance training (HL-RT) on muscle strength, muscle mass, physical function, patient-reported outcomes, and adherence to training in clinical musculoskeletal populations.Data sourcesWeb of Science, Cochrane Central, Medline, Embase, SportDiscus was searched on the 30th May 2022.Review methodsThis study was conducted as a systematic review and meta-analysis. Randomized Controlled Trials (RCTs) were included if they (i) included patients, (ii) comprised of a BFR-RT intervention protocol and a group who performed HL-RT (≥ 70%1RM) for at least eight exercise sessions, and (iii) involved at least 1 exercise that targeted the lower limbs. The Cochrane Risk of Bias tool was used to evaluate the risk of bias. The meta-analyses were performed using a random effects model with an adjustment to the confidence interval.ResultsSeven RCTs comprising 303 participants (BFR-RT: n = 151; HL-RT: n = 152) were identified. HL-RT and BFR-RT showed similar gains in dynamic (1-10RM) knee extensor strength and leg press strength, quadriceps cross sectional area, sit-to-stand performance, and patient reported pain and function. There was a moderate effect favoring BFR-RT for increasing maximal isometric knee extensor strength. The grading of certainty in evidence was low-to-very low for all outcome variables.ConclusionThis systematic review and meta-analysis extends our current knowledge about BFR-RT and HL-RT as equally effective exercise methods for inducing gains in maximal muscle strength in healthy populations, by now also comprising patients suffering from various clinical musculoskeletal conditions. The certainty in the estimates was low-to-very low, prompting the inclusion of future higher-quality trials.Trial registrationPROSPERO ID (CRD42022337173). Registered June 18th 2022.

Influence of Second-Generation Oral Contraceptives on Muscle Recovery after Repeated Resistance Exercise in Trained Females.

Oral contraceptives (OCs) are commonly used by female athletes, but their effects on skeletal muscle are still poorly understood. We investigated if physically trained females using second-generation OCs differed from nonusers of OCs in the recovery of muscle function and muscle damage markers after repeated resistance exercise sessions. We recruited 20 trained second-generation OC users and 20 trained nonusers to perform three strenuous resistance exercise sessions. Before, and 3, 24, and 48 h after exercise, blood samples were collected, and participants were evaluated for muscle soreness, maximal isometric and isokinetic muscle strength, vertical jump height, Wingate power performance, leg press strength, and intermittent recovery capacity (yo-yo test). All participants were provided with an energy-macronutrient-balanced diet during the experimental period. After resistance exercise, maximal isometric and isokinetic muscle strength, rate of force development, vertical jump height, and Wingate peak and average power were reduced, whereas markers of muscle damage were increased in both groups (P < 0.05). OC users experienced a greater reduction in isokinetic strength 3, 24, and 48 h after exercise compared with nonusers of OCs (interaction: P < 0.05). No other interactions were observed. We demonstrate that measures of muscle strength recovery after three strenuous resistance exercise sessions are comparable between trained females using second-generation OCs and nonusers of OCs. However, group differences were observed for isolated dynamic (isokinetic) muscle strength, suggesting a marginal benefit of not using OCs when accelerated recovery is needed.

The effect of Post Activation Potentiation in children’s jumping performance

Objectives: The objective of the present study was to investigate a) the potential effect of PAP in children’s jumping performance and b) the optimal time frame of the potential PAP effects in the same population Methods: Ten healthy male children (age: 12.2 ± 1.2; n= 7, pre-PHV and n= 3, post-PHV) conducted a single set of heavy resistance training (3RM leg press) followed by five maximal counter-movement-jump (CMJ) at different passive rest periods (1 min, 2 min, 4 min, 6 min, 8 min). Baseline 3RM leg press strength test, countermovement jump (CMJ), and peak height velocity (PHV) were assessed. Primary outcome: jump height (cm) pre and post-PAP. Results: No significant differences were observed between jumping heights pre- and post-PAP at any of the selected rest periods (1 min ES: 0.0; 2 min ES: 0.25; 4 min ES: 0.09; 6 min: ES: 0.03; 8 min ES: 0.15, p = 0.99). Pre vs. post-PAP jumping heights did not differ significantly even when participants were grouped according to peak height velocity (PHV) (pre-PHV: p = 0.97, ES: - 0.07 to 0.26 and post-PHV: p = 0.99, ES: - 0.11 to 0.37). Conclusion: The results indicate that a single set of a heavy lower-body resistance training protocol induces no significant PAP effect in healthy male preadolescent children, irrespective of the rest period used. Future studies with larger sample sizes are needed to confirm the results.

Contribution of different strength determinants on distinct phases of Olympic rowing performance in adolescent athletes

ABSTRACT Aerobic metabolism dominates Olympic rowing, but research on the relative contribution of strength and power demands is limited. This study aimed to identify the contribution of different strength determinants for distinct phases of rowing ergometer performance. The cross-sectional analysis comprised of 14 rowing athletes (4 female, 10 male, age: 18.8 ± 3.0y, 16.9 ± 2.2y). Measurements included anthropometrics, maximal strength of leg press, trunk extension and flexion, mid-thigh pull (MTP) and handgrip strength, VO2max, and a 2000 m time trial, where peak forces at the start, middle and end phase were assessed. Additionally, rate of force development (RFD) was assessed during the isometric leg press and MTP with intervals of 150, 350 ms and 150, 300 ms, respectively. Stepwise regression models for ergometer performance showed that the start phase was mainly explained by maximal trunk extension and RFD 300 ms of MTP (R2 = 0.91, p < 0.001) and the middle section by VO2max, maximal leg press strength and sitting height (R2 = 0.84, p < 0.001). For the end phase, a best fit was observed for trunk flexion, RFD 350 ms of leg press, body height and sex (R2 = 0.97 p < 0.001), whereas absolute VO2max, trunk flexion and sex explained variance over the entire 2000 m time trial (R2 = 0.98, p < 0.001). It appears that for the high acceleration in the start phase, force transmission through maximum strength for trunk extension is essential, while fast power production along the kinetic chain is also relevant. Additionally, the results support that maximal force complements the reliance on VO2max. Further intervention studies are needed to refine training recommendations.

Efficacy and Feasibility of Presurgical Exercise in Bladder Cancer Patients Scheduled for Open Radical Cystectomy.

This study aimed to examine the feasibility and potential efficacy of presurgical exercise in patients with bladder cancer scheduled for open radical cystectomy with follow-up postsurgery. Prospective single-group design with assessments at baseline, presurgery, and 3 months postsurgery was used in this study. Multimodal supervised resistance and aerobic exercise was undertaken 2-3 d·wk -1 at moderate intensity for a median of 3.5 wk (interquartile range [IQR] = 1.3-5.6). Feasibility was assessed by recruitment and completion rates, patient safety, program tolerance, adherence, and compliance. Lean and fat mass were assessed by dual-energy x-ray absorptiometry, physical function by a battery of tests (chest press and leg press strength, 6-min walk test [6MWT], timed up-and-go, repeated chair rise), and quality of life (QoL), psychological distress, and body image by questionnaire. Hospital length of stay (LOS) and complications were assessed by medical records. Thirty-seven patients were referred with 20 recruited (67.3 ± 12.2 yr) and a presurgery intervention completion rate of 80% (16 of 20). The individual median program adherence was 100.0% (IQR = 89.4-100.0) with compliance of 100.0% (IQR = 90.5-100.0) for resistance exercise and 81.8% (IQR = 55.0-99.5) for aerobic exercise. There were no exercise-related adverse events. Body composition did not change presurgery; however, there were improvements ( P < 0.05) in leg press strength (16%), 6MWT distance (8%), timed up-and-go (12%), chair rise (10%), and multiple QoL domains including mental health. Median LOS was 8.0 d (IQR = 7.0, 15.0). Postsurgery, there were declines in components of QoL and apparent body image dissatisfaction. A preradical cystectomy exercise program is feasible, safe, and well tolerated with improvements in physical function and QoL. Supervised multimodal exercise in bladder cancer patients before cystectomy can enhance physical and mental health potentially buffering the effects of surgery.

Limits of stability and falls during a multicomponent exercise program in faller older adults: A retrospective cohort study

Background/ObjetivesMulticomponent exercise programs have been demonstrated to prevent falls in older adults. However, the underlying responsible mechanisms are not clear. We aimed to analyze the association between changes in the limits of stability (LOS) as a relevant balance component, and falls occurrence during a multicomponent physical exercise program. MethodsRetrospective study, including ninety-one participants who had experienced a fall in the previous year, and were attended in a falls unit. All of them were included in a twice-a-week multicomponent exercise program during 16 weeks. Pre- and post-program measurements were collected for leg press, gait speed, the short physical performance battery (SPPB), and LOS (point of excursion [POE] and maximal excursion [MEX]) with posturography. Falls occurrence was assessed between the beginning and the completion of the exercise program (16 week). ResultsThe mean age was 77.2 years, and 72 were female. Thirty-two participants fell at least once during the exercise period. The global baseline POE was 47.6 %, and the MEX was 64.7 %, and there were no differences between fallers and nonfallers. Nonfallers presented greater improvements in POE (6.3 % versus 1.3 %; p < .05) and MEX (9.2 % versus 3.0 %; p < .01) than fallers. The POE and MEX were independently associated with a reduced probability of having had a fall, OR: 0.95 (95 % CI: 0.91 to 0.99) and 0.94 (95 % CI: 0.90 to 0.99), respectively. Changes in SPPB results or leg press strength were not associated with decreased falls. Adjusted probability of fall occurrence decreased by 5 % and 6 % per 1 % improvement in absolute values in POE and MEX, respectively. ConclusionsImprovements in LOS after a multicomponent physical exercise program in older adults with previous falls may be associated with a decreased occurrence of falls.

Relative leg press strength relates to activity energy expenditure in older women: Implications for exercise prescription

Limited work has evaluated how leg press strength (LPS), relative to body mass (i.e., rLPS), affects heart rate (HR) responses during activities of daily living. Such information would prove useful by informing a specific level of rLPS needed to promote independent mobility and physical activity. Secondary analyses were performed on baseline measures of 76 untrained older (65 ± 4 y) women. After familiarization, one-repetition maximum leg press was converted to rLPS by dividing the external load lifted (kg) by body mass (BM). Participants were stratified according to percentile of age-group norms of rLPS: ≤50 % (low, ≤0.99 kg/BM, n = 15), 51–89 % (middle, 1.0–1.31 kg/BM, n = 31), and ≥90 % (high, ≥1.32 kg/BM, n = 30). HR was measured at rest and during laboratory-based tasks including fixed-speed (0.89 m·s−1) non-graded treadmill walking, graded (2.5 %) treadmill walking, and stair stepping. Maximal oxygen uptake (V̇O2max) was measured via indirect calorimetry. Doubly labeled water was used to quantify activity energy expenditure (AEE) over a 14-d period. Relative LPS per group were: 0.85 ± 0.12 (low), 1.16 ± 0.09 (middle), and 1.55 ± 0.25 (high) (p < 0.001). Significant between-group differences in HR emerged during both walking tasks and stair stepping – with the high rLPS group having the lowest HR. AEE between-group comparisons did not yield statistical significance (p = 0.084), however, rLPS correlated with AEE (r = 0.234, p = 0.042) and V̇O2max (r = 0.430, p < 0.001). Such findings suggest a higher rLPS attenuates HR for weight-bearing activities while also demonstrating a significant, albeit modest, positive link to AEE among older women. This information may be especially relevant for informing thresholds of rLPS linked to mobility and functional independence in older women.

Lifelong Strength Versus Endurance Training: Differential Adaptations In Efferent Neural Drive And Spinal α-motoneuron Excitability

PURPOSE: Neural factors play a critical role in the age-related decline in maximal strength and rate of force development (RFD). However, it is uncertain how the neural attenuation may be mitigated by strength or endurance training, respectively. METHODS: In this study we applied evoked spinal motoneuron recordings to examine efferent neural drive (V/Msup during maximal voluntary contraction; MVC) and α-motoneuron excitability (Hmax/Mmax at 10% MVC) in a total of 69 older (>65 yrs) and younger (<35 yrs) strength athletes (n = 21), endurance athletes (n = 17) and control subjects (n = 31). RESULTS: Leg press strength (one repetition maximum: 1RM) but not maximal oxygen uptake (V̇O2max), were positively associated with V/Msup (r = 0.60, p < 0.001). Leg press 1RM and RFD were higher (all p < 0.05) in older strength athletes (1RM: 164 ± 18 kg; RFD (0-200 ms); 4262 ± 1022 N·s-1) than endurance athletes (1RM: 132 ± 25 kg; RFD: 3080 ± 669 N·s-1) and older controls (1RM: 109 ± 15 kg; RFD: 2202 ± 915 N·s-1), but lower compared to training-matched young groups (p < 0.05). V̇O2max was positively associated with Hmax/Mmax (r = 0.47, p < 0.001) while no correlation was observed for 1RM. V̇O2max was higher (all p < 0.05) in older endurance athletes (47.6 ± 7.6 ml·kg-1·min-1) than in older strength athletes (30.9 ± 6.0 ml·kg-1·min-1) and older controls (34.2 ± 4.4 ml·kg-1·min-1), but lower than all young groups (p < 0.001). CONCLUSIONS: Across the life span the plasticity in skeletal muscle strength and aerobic capacity, respectively, seems to be associated with differential neural factors. Specifically, chronic strength training seems to result in a higher efferent neural drive during maximal muscle contractions (elevated V-wave responses), largely dependent on corticospinal factors, whereas chronic endurance training appears to be related to a high α-motoneuron excitability, at least during low-level muscle contractions. Since high efferent neural drive is a key component for strong muscle contractions with age, strength training should be emphasized for the ability to carry out force-dependent tasks at older age.

Vitamin D supplementation and increased dairy protein intake do not affect muscle strength or physical function in healthy 6-8-year-old children: the D-pro randomized trial.

PurposeTo investigate separate and combined effects of vitamin D supplementation during the extended winter and increased dairy protein intake on muscle strength and physical function in children, and furthermore to explore potential sex differences.MethodsIn a 2 × 2-factorial, randomized winter trial, 183 healthy, 6–8-year-old children received blinded tablets with 20 µg/day vitamin D3 or placebo, and substituted 260 g/day dairy with yogurts with high (HP, 10 g protein/100 g) or normal protein content (NP, 3.5 g protein/100 g) for 24 weeks during winter at 55° N. We measured maximal isometric handgrip and leg press strength, and physical function by jump tests and a 30 s sit-to-stand test. Physical activity was measured by 7-day accelerometry.ResultsBaseline (mean ± SD) serum 25-hydroxyvitamin D was 80.8 ± 17.2 nmol/L, which increased to 88.7 ± 17.6 nmol/L with vitamin D supplementation and decreased to 48.4 ± 19.2 nmol/L with placebo. Baseline protein intake was 15.5 ± 2.4 E%, which increased to 18.4 ± 3.4 E% with HP and was unchanged with NP. We found no separate or combined effects of vitamin D supplementation and/or increased dairy protein intake on muscle strength or physical function (all P > 0.20). There was an interaction on the sit-to-stand test (Pvitamin×yogurt = 0.02), which however disappeared after adjusting for physical activity (P = 0.16). Further, vitamin D supplementation increased leg press strength relatively more in girls compared to boys (mean [95% CI] 158 [17, 299] N; Pvitamin×sex = 0.047).ConclusionOverall, vitamin D and dairy protein supplementation during the extended winter did not affect muscle strength or physical function in healthy children. Potential sex differences of vitamin D supplementation should be investigated further.Registered at clinicaltrials.govNCT0395673.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00394-022-02912-0.

Longitudinal Changes in Skeletal Muscle Metabolism, Oxygen Uptake, and Myosteatosis During Cardiotoxic Treatment for Early-Stage Breast Cancer

BackgroundWhile cardiotoxic chemotherapy is known to negatively impact cardiac function and hemoglobin levels, the impact on skeletal muscle has been understudied among patients. The purpose was to longitudinally characterize myosteatosis (muscle fat), skeletal muscle metabolism, and oxygen (O2) consumption during cardiotoxic chemotherapy for breast cancer.Patients and MethodsThirty-four patients with stage I-III breast cancer were enrolled before trastuzumab-containing and/or anthracycline-containing chemotherapy. We used magnetic resonance imaging to non-invasively quantify thigh myosteatosis (fat-water imaging), and lower leg metabolism (31P spectroscopy), O2 consumption (custom techniques), and peak power output during single-leg plantarflexion exercise at pre-, mid-, end-chemotherapy, and 1-year. We also measured pulmonary VO2peak and maximal leg press strength.ResultsDuring chemotherapy, VO2peak and leg press strength decreased while peak plantarflexion power output was maintained. At mid-chemotherapy, hemoglobin decreased (16%) and lower leg blood flow increased (37%) to maintain lower leg O2 delivery; exercise Pi:PCr and myosteatosis increased. Between mid- and end-chemotherapy, lower leg O2 extraction (28%) and O2 consumption (21%) increased, while plantarflexion exercise efficiency (watts/O2 consumed) decreased. At one year, VO2peak and leg press strength returned to pre-chemotherapy levels, but lower leg exercise O2 extraction, consumption and Pi:PCr, and myosteatosis remained elevated.ConclusionLower leg skeletal muscle blood flow and O2 extraction adapt to compensate for chemotherapy-related hemoglobin reduction for small muscle mass exercise but are insufficient to maintain large muscle mass exercise (pulmonary VO2peak, leg press strength). The excess O2 required to perform work, increased Pi:PCr ratio and myosteatosis together suggest suppressed fat oxidation during chemotherapy.

Linear Motor Driven Leg-Press Dynamometer for Testing, Training, and Rehabilitation: A Scoping Review with a Focus on the Concept of Serial Stretch Loading.

Background: The purpose of this scoping review was to analyze the evidence of acute and long-term effects of the application of leg-press strength training with or without serial stretch-loading stimuli on various biomechanical and physiological outcomes. Methods: This review was performed in accordance with PRISMA for Scoping Reviews recommendations, and two researchers independently searched the following databases: PubMed, Web of Science, Scopus, ScienceDirect, ProQuest, Cochrane, and Google Scholar. All studies that used unique leg-press device for testing, acute responses and long-term adaptation were included in this review, irrespective of the measured outcomes. A total of 13 studies were included in this review, with 5 focused on the testing capabilities of the device and acute training responses and 8 focused on the long-term adaptations in various physical and physiological outcomes. Results: Regarding the acute responses after leg-press strength training with or without serial stretch-loading stimuli, visible changes were observed in the muscle force, rate of force development, and hormonal concentrations between pre- and postmenopausal women (only one study). Long-term studies revealed different training adaptations after performing leg-press strength training with unique serial stretch-loading stimuli. A positive trend for leg-press strength training with serial stretch-loading was recorded in the young population and athletes; however, more variable training effects favoring one or the other approach were achieved in the older population. Conclusions: In summary, this review shows the uniqueness and usability of a leg-press device that is capable of various exercising modes, including special serial stretch-loading stimuli. The use of this device can serve as a positive addition to training regiments, and the main application appears to be suitable for rehabilitation needs.

Effects of Detraining on Muscle Strength and Hypertrophy Induced by Resistance Training: A Systematic Review

A detraining period after resistance training causes a significant decrease in trained-induced muscular adaptations. However, it is unclear how long muscle strength and hypertrophy gains last after different detraining periods. Thus, the present systematic review with meta-analysis aimed to evaluate the chronic effects of detraining on muscle strength and hypertrophy induced by resistance training. Searches were conducted on PubMed, Scopus, EBSCO, CINAHL, CENTRAL, and Web of Science. The difference in means and pooled standard deviations of outcomes were converted into Hedges’ g effect sizes (g). Twenty randomized and non-randomized trials (high and moderate risks of bias, respectively, and fair quality) were included for qualitative analysis of muscle strength and hypertrophy, while only two studies were included in the meta-analysis for maximum muscle strength. The resistance training group presented a significant increase in one-repetition maximum (1RM) chest press (g: 4.43 [3.65; 5.22], p &lt; 0.001) and 1RM leg press strength (g: 4.47 [2.12; 6.82], p &lt; 0.001) after training. The strength gains observed in the resistance training group were also maintained after 16–24 weeks of detraining (g: 1.99 [0.62; 3.36], p = 0.004; and g: 3.16 [0.82; 5.50], p = 0.008; respectively), when compared to the non-exercise control group. However, 1RM chest press and leg press strength level was similar between groups after 32 (g: 1.81 [−0.59; 4.21], p = 0.139; and g: 2.34 [−0.48; 5.16], p = 0.104; respectively) and 48 weeks of detraining (g: 1.01 [−0.76; 2.79], p = 0.263; and g: 1.16 [−1.09; 3.42], p = 0.311; respectively). There was not enough data to conduct a meta-analysis on muscular hypertrophy. In conclusion, the present systematic review and meta-analysis demonstrated that, when taking random error into account, there is no sufficient high-quality evidence to make any unbiased claim about how long changes in muscle strength induced by RT last after a DT period. Moreover, the effect of different DT periods on muscle hypertrophy induced by RT remains unknown since there was not enough data to conduct a meta-analysis with this variable.