Lower Limb Strength Performance Research Articles

Investigating the impact of inter-limb asymmetry in hamstring strength on jump, sprint, and strength performance in young athletes: comparing the role of gross force.

The main purpose of this cross-sectional study was to examine the impact of the inter-limb asymmetry of hamstring strength on jump, sprint and strength performance and to compare the effects of inter-limb asymmetry of hamstring strength with gross force (GF) of the hamstring on these physical qualities in youth volleyball athletes. Eighty-one youth volleyball players (age: 16.6 ± 1.9years; training experience: 3.0 ± 0.9years; height: 191.4 ± 7.1cm; body mass: 78.5 ± 12.9kg; lean body mass: 63.5 ± 10.5kg; body fat rate: 18.6% ± 6.1%) performed a mid-season battery of tests consisting of morphological test, depth jump (DJ), counter movement jump (CMJ), squat jump (SJ), 10m sprint, isometric mid-thigh pull (IMTP) and hamstring strength test. All tests reported good to excellent reliability (ICC range = 0.815-0.996) and acceptable variability (CV range = 3.26-7.84%). Results show a significant negative relationship between inter-limb asymmetry of hamstring strength and all physical qualities (r = -0.271 to -0.445; p < 0.05), and a significant positive relationship between GF of hamstring and all physical qualities (r = 0.303 to 0.664; p < 0.05). Additionally, GF of hamstring was more relevant to IMTP-PF (peak force) (r = 0.664) and inter-limb asymmetry of hamstring strength was more relevant to 10m sprint (r = -0.445). The findings from this study indicate that, for youth athletes, the GF of the hamstring is crucial for overall lower limb strength performance, and the importance of inter-limb symmetry of hamstring strength increases with the complexity of the task.

The effects of lower extremity muscle strength characteristics on grab and track start performance in young competitive swimmers

BACKGROUND: Limited data exist regarding segmental contributions of lower extremity muscles to the swim start performance during different start techniques in young swimmers. OBJECTIVE: To determine the differences in the kinematic parameters between the grab start (GS) and track start (TS) techniques and assess the interactions between the lower limb muscle strength and swim start performance. METHODS: A total of 40 swimmers, 20 girls (age: 13.70 ± 1.80 y, height: 161.65 ± 8.28 cm, body weight: 53.70 ± 8.65 kg) and 20 boys (age: 13.90 ± 1.45 y, height: 160.95 ± 12.70 cm, body weight: 52.95 ± 12.64 kg), 13–16 y of age, at the competitive level were recruited. Ankle, hip, and knee muscles were tested isokinetically at 60∘/s and the tests were spread over 24 h to avoid fatigue. Several elements relating to GS and TS were measured using a motion pick-up video camera. RESULTS: The angle of entry (EA) at water and knee joint angle (KA) were significantly greater during GS both for boys (EA: 44.18 ± 1.07∘ vs. 43.03 ± 1.28∘; KA: 112.10 ± 15.25∘ vs. 107.21 ± 21.13)∘ and girls (45.09 ± 1.28∘ vs. 43.36 ± 1.55∘; KA: 103.08 ± 11.21∘ vs. 97.45 ± 19.52∘, p&lt; 0.05). Flight time (FT), flight distance (FD), KA, and flight velocity (FV) were significantly higher for boys both during GS and TS, whereas EA was significantly lower for boys during GS compared to girls (p&lt; 0.05). Lower limb strength performance was positively significantly correlated with FT, FD, and FV both during GS and TS (p&lt; 0.05). Hip muscle strength was inversely correlated with the EA both during GS and TS (p&lt; 0.05). The combination of the knee, ankle, and hip extensor and flexor muscle strengths had a greater effect during GS (35% vs. 29%) in RT, (48% vs. 46%) in FT, (59% vs. 57%) in FD, and (63% vs. 57%) in FV compared to the TS. CONCLUSIONS: Incorporating lower body strength training into the swimming training schedule may improve swim start performance variables during grab start and track start techniques.

Longitudinal development of 5m sprint performance in young female tennis players

ABSTRACT Sprint performance over short distances is a central component in young tennis players’ development. This study aimed to examine the longitudinal development of sprint performance in young female tennis players, and to investigate differences between performance levels. Also potentially explanatory variables were investigated. Female tennis players aged 10–15 (N = 167) participated in a, mixed-longitudinal study (n = 48 elite; n = 119 sub-elite). Players were measured annually on the 5 m sprint as well as for possible explaining variables for 5 m sprint performance development (age, height, body mass, maturity status, lower limb explosive strength). Multilevel analysis was used to obtain a developmental model. Moreover, it was possible to predict sprint performance (5 m) based on chronological age, body size given by height, and lower limb strength performance (p < .05). Significant different developmental patterns were found for elite and sub-elite players, with elite players aged 10–14 being faster. After age 14, no significant differences were found in sprint performance between elite and sub-elite players (p > . 05). Sprint performance is an important characteristic of young female tennis players and seemed to depend on growth and maturation in parallel to physical fitness.

Independent and Joint Associations of Physical Activity and Dietary Behavior with Older Adults' Lower Limb Strength.

Studies have indicated that sufficient physical activity levels and balanced dietary behavior are independently related to physical function in older populations; however, their joint association with physical function remain unclear. This study examined the independent and combined associations of sufficient physical activity and balanced selection of foods with lower limb strength among 122 older Taiwanese adults living in community (mean age: 69.9 ± 5.0 years). The assessments included accelerometer-measured moderate-to-vigorous physical activity (MVPA) and self-reported selection of foods. Lower limb strength performance was measured using the five times sit-to-stand test. Binary logistic regression analyses were performed to estimate the associations in question before and after adjusting for potential confounders. The results showed that in the adjusted model, lower limb strength had no significant independent association with either meeting the recommended level of MVPA or balanced selection of foods. Compared to older adults who neither met the recommended MVPA level nor reported a balanced selection of foods, those who conformed to both these criteria were more likely to have better lower limb strength (odds ratio = 6.28, 95% confidence interval = 1.36–29.01) after adjusting for covariates. Health promotion initiatives addressing disability prevention for older adults need to consider promoting both MVPA and food selection.

Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyses

Creatine is the most widely used supplementation to increase strength performance. However, the few meta-analyses are more than 10 years old and suffer from inclusion bias such as the absence of randomization and placebo, the diversity of the inclusion criteria (aerobic/endurance, anaerobic/strength), no evaluation on specific muscles or group of muscles, and the considerable amount of conflicting results within the last decade. The objective of this systematic review was to evaluate meta-analyzed effects of creatine supplementation on lower limb strength performance. We conducted a systematic review and meta-analyses of all randomized controlled trials comparing creatine supplementation with a placebo, with strength performance of the lower limbs measured in exercises lasting less than 3 min. The search strategy used the keywords "creatine supplementation" and "performance". Dependent variables were creatine loading, total dose, duration, the time-intervals between baseline (T0) and the end of the supplementation (T1), as well as any training during supplementation. Independent variables were age, sex, and level of physical activity at baseline. We conducted meta-analyses at T1, and on changes between T0 and T1. Each meta-analysis was stratified within lower limb muscle groups and exercise tests. We included 60 studies (646 individuals in the creatine supplementation group and 651 controls). At T1, the effect size (ES) among stratification for squat and leg press were, respectively, 0.336 (95 % CI 0.047-0.625, p = 0.023) and 0.297 (95 % CI 0.098-0.496, p = 0.003). Overall quadriceps ES was 0.266 (95 % CI 0.150-0.381, p < 0.001). Global lower limb ES was 0.235 (95 % CI 0.125-0.346, p < 0.001). Meta-analysis on changes between T0 and T1 gave similar results. The meta-regression showed no links with characteristics of population or of supplementation, demonstrating the creatine efficacy effects, independent of all listed conditions. Creatine supplementation is effective in lower limb strength performance for exercise with a duration of less than 3 min, independent of population characteristic, training protocols, and supplementary doses and duration.

Prediction of Lower Limb Isometric Strength from Regional Muscle Mass Variables in Adolescents

The relationship between muscle size and strength has been published in the literature, however less is known about its actual association for adolescents. The identification of anthropometric muscle mass indicators that best predict strength across age taking in account growth and maturation processes, must be useful in field settings for screening sport talents, and sport training with young. PURPOSE: To analyze the association between lower-limb strength (LLS) and regional skeletal muscle mass (SMM) variables in young athletes and non-athletes. Secondly, to identify which regional SMM indicators are more successful predictors of LLS after adjusted for maturation. METHODS: SMM variables were assessed by anthropometric measures in 166 adolescents between 12 and 18 years old (15.2 ± 1.7 yrs, BMI = 21.9 ± 3.9 kg·m-2). The volunteers were recruited from local high-schools and local sport clubs. Athletes (AT) and non-athletes (NAT) were identified using an ad hoc questionnaire (NA = 99, 42 boys, 57 girls, and A = 67, 42 boys, 25 girls). Skeletal muscle mass (SMM) was calculated by anthropometric-derived equations. A dynamometer device was used to assess LLS. Partial correlations were carried out to determine associations between BC variables and strength values. The best-correlated variables with LLS performance were included in a stepwise regression analysis to determine SMM predictors. RESULTS: As expected AT were stronger than NA (80.3 ± 32.3 vs 58.4 ± 27.1 kg, p<0.001). The best correlation between SMM variables and LLS test was for total SMM in NAT boys after controlled by height (r = 0.520, p<0.001). When participants were pooled together, SMM, athlete condition and height were predictors of LLS test (R-squared = 0.484, p<0.001). Similar results were found for an alternative model including mid-calf corrected girth (CCG), athlete condition, gender and height (R-squared = 0.485, p<0.001). Surprisingly, age at peak height velocity was not found as a predictor of LLS. CONCLUSIONS: In accordance with other studies, our results confirm that lower-limb strength performance in adolescents was partially dependent on SMM. The main finding was that a simple measure as CCG can contribute to develop youth predictive models of sport performance and talent identification. Funded by Spanish Ministry of Economy and Competiveness (grant: DEP2011-30565)