Inter-limb asymmetry during rehabilitation understanding formulas and monitoring the "magnitude" and "direction"

This article outlines how asymmetry can be used during the rehabilitation process for practitioners, and the importance of both the magnitude and direction of an inter-limb asymmetry

Comparison of bilateral vs. unilateral-biased strength and power training interventions on measures of physical performance in elite youth soccer players

The aim of the present study was to compare the effects of bilateral and unilateral-biased strength and power training programs on measures of physical performance in male youth soccer players. Twenty-three elite youth players (age: 17.6 1.2 years) were randomly assigned to either a unilateral (n = 11) or a bilateral (n = 12) group, who completed a strength and power intervention, twice per week for 6-weeks. The unilateral group completed rear foot elevated split squats (RFESS), single leg countermovement jumps (SLCMJ), single leg drop jumps (SLDJ) and single leg broad jumps (SLBJ). The bilateral group intervention performed back squats, countermovement jumps (CMJ), drop jumps (DJ) and broad jumps (BJ). A 2 x 2 repeated measures ANOVA showed no between-group differences. However, within-group differences were evident. The bilateral training group showed significant (p < 0.05) improvements in back squat strength (d = 1.27; %Δ = 26.01), RFESS strength (d = 1.64; %Δ = 23.34), BJ (d = 0.76; %Δ = 5.12), 10 m (d = -1.17; %Δ = 4.29) and 30 m (d = -0.88; %Δ = 2.10) performance. The unilateral group showed significant (p < 0.05) improvements in RFESS strength (d = 1.40; %Δ = 33.29), SLCMJ on the left leg (d = 0.76; %Δ = 9.84), SLBJ on the left leg (d = 0.97; %Δ = 6.50), 10 m (d = -1.50; %Δ = 5.20), and 505 on the right leg (d = -0.78; %Δ = 2.80). Standardised mean differences showed that bilateral training favoured improvements in back squat strength and unilateral training favoured improvements in RFESS strength, SLDJ on the right leg and 505 on the right leg. These results show that although both training interventions demonstrated trivial to large improvements in physical performance, the notion of training specificity was evident with unilateral training showing greater improvements in unilateral test measures

Acute effect of repeated sprints on inter-limb asymmetries during unilateral jumping

The aim of the present study was to investigate the effects of multiple repeated sprints on unilateral jump performance and inter-limb asymmetries. Eighteen recreationally active males performed three single leg countermovement jumps (SLCMJ) as baseline data. The repeated sprint protocol was 6 x 40 m with 20 seconds of passive rest between each sprint. This protocol was conducted four times, each set separated by four minutes of rest. Within that rest period, subjects performed one SLCMJ on each limb after two minutes of rest. A one-way ANOVA showed significant reductions (p < 0.05; ES = -0.52 to -0.99) in jump height on both limbs after each set relative to baseline. Inter-limb asymmetries increased at each time point and ranged from 7.62-14.67%, with significant increases in asymmetry seen after sets three (p = 0.046) and four (p = 0.002). Significant increases in sprint time were shown between sprints one and six in each set (p ≤ 0.01). A fatigue index (%) was also calculated and showed an exponential increase from 5.74% (set one) to 13.50% (set four), with significant differences between all sets (p < 0.001) with the exception of sets three and four. Results from this study show that a 6 x 40 m repeated sprint protocol is a sufficient dose for implementing acute fatigue in recreationally active subjects. This was manifested by reductions in jump height at all time points and jump height asymmetries after the third and fourth sets. These findings indicate that jump height from unilateral jump testing may be a useful metric to use during the monitoring process in recreationally trained athletes

A comparison of 3 different unilateral strength training strategies to enhance jumping performance and decrease interlimb asymmetries in soccer players

Purpose: This study compared the effects of performing different unilateral strength training interventions on unilateral and bilateral jumping performance and their related asymmetries in young soccer players. Methods: Forty-five male young (U-17) soccer players were randomly assigned to three eccentric overload training programs: The first group executed the same volume with both legs starting with the weaker leg (SVW, n=15), the second group carried out the double volume with the weaker leg and also starting with the weaker leg (DVW, n=15), and the third group performed the same volume with both legs starting with the stronger leg (SVS, n=15). Jumping performance assessment included a single-leg horizontal jump test, a triple single-leg horizontal jump test, a bilateral countermovement (CMJ) jump test and unilateral countermovement jump test. Asymmetries were also analyzed in the unilateral jumping tests. Results: CMJ was improved (effect size [ES]: 0.27-0.48) and CMJ asymmetry was possibly reduced (ES: 0.08-0.24) in all groups. Substantial improvements were found in triple hop (ES: 0.52-0.71) in SVW and DVW, and triple hop asymmetry was substantially decreased (ES: 0.88) in DVW. Between-group analysis showed a substantial better performance in triple hop and horizontal hop with right leg in SVW and DVW compared to SVS. Conclusions: Unilateral strength training programs were shown to substantially improve bilateral jumping performance, while unilateral jumping was substantially enhanced in those groups that started the training session with the weaker leg. Finally, between-limbs asymmetries in the triple hop were mainly reduced through performing the double volume with the weaker leg

Comparison of three eccentric overload training strategies on power output and interlimb asymmetry in youth soccer players

Background: The present study compared the effects of performing the lateral squat exercise in three different formats from eccentric overload training on concentric/eccentric peak/mean power and inter-limb asymmetries in young soccer players. Methods: Forty-five young male (U-17) soccer players were distributed into three groups. Two groups performed the same training volume with both legs, beginning with the weaker leg (SVW, n = 15) or with the stronger leg (SVS, n = 15). The third group executed double volume with the weaker leg and also commenced with such leg (DVW, n = 15) in the lateral squat during a 10-week period. Pre- and post-intervention metrics included concentric and eccentric peak/mean power during the lateral squat test and their corresponding asymmetries. Results: All groups improved all power variables. Concentric mean and peak power asymmetry were substantially reduced in the SVW (ES: 0.89), DVW (ES: 0.43), and in SVW (ES: 1.60). Eccentric mean and peak power asymmetry were also substantially decreased in SVW (ES: 0.81) and in DVW (ES: 0.68). Between-group analyses showed substantially better performance in concentric and eccentric variables with stronger and weaker legs in SVW and DVW groups compared with SVS. Conclusions: Those groups which started with the weaker leg showed greater both power enhancements and reductions on inter-limb asymmetries

Effects of three different combined training interventions on jump, change of direction, power performance, and inter-limb asymmetry in male youth soccer players

Background: This study compared the effects of performing different unilateral combined training interventions on diverse vertical and horizontal jumping performance parameters, change of direction, concentric and eccentric mean power, and their associated inter-limb asymmetries in young soccer players. Methods: Forty-seven young male soccer players (age: 15.5 ± 0.9 years) were distributed into three groups. Two groups performed the same training volume with both legs, beginning with the weaker leg (Stronger Volume Weaker leg group (SVW), n = 14) or with the stronger leg (Stronger Volume Stronger leg group, (SVS), n = 15). The third group executed double the volume with the weaker leg and also commenced with such leg (Double Volume Weaker leg group (DVW), n = 16) during a 10-week period. Pre- and post-intervention tests included a single-leg hop, single-leg lateral hop, triple hop, bilateral and unilateral countermovement jumps, a change of direction speed test, concentric and eccentric mean power during the lateral squat test, and their corresponding asymmetries. Results: Single-leg hop weaker leg, triple hop weaker leg, and bilateral countermovement jump improvements were achieved in the SVW (ES: 0.29 to 0.46) and DVW (ES: 0.55 to 0.73) groups. Between-groups analysis showed better results in single-leg hop in the SVW and DVW compared to group SVS. The DVW group achieved better improvements in countermovement jump in comparison to groups SVS and SVW. Conclusions: Groups that started with the weaker leg seemed to achieve a greater volume of significant changes than when starting with the stronger leg. Performing a double volume on the weaker limb does not guarantee further improved performance compared to other groups

Effects of 8-weeks of isoinertial vs. cable-resistance training on motor skills performance and interlimb asymmetries

Two training interventions conducted on youth handball athletes

Effects of direction-specific training interventions on physical performance and inter-limb asymmetries

This study analyzed the effects of two different training programs on functional performance and inter-limb asymmetries in basketball players. Twenty-four elite youth basketball players were randomly assigned to a training program including variable unilateral horizontal movements (VUH, n = 12) or unilateral lateral movements (VUL, n = 12). Eccentric-overload training (EOT) was performed twice a week for a six-week period. Functional performance assessment included a countermovement jump test, unilateral multidirectional jumping tests (i.e., lateral, horizontal, and vertical), a rebound jump test, a limb symmetry index, a 25 m linear sprint test, and several change of direction (COD) tests. Within-group analysis showed substantial improvements in almost all functional tests in both groups (ES = 0.35−0.89). Furthermore, almost all jumping asymmetries were improved in both groups (ES = 0.38−0.69) except for vertical jumping asymmetry in VUL (ES = −0.04). Between-group analyses showed a substantial and possibly better performance in vertical jumping asymmetry and 5 m in VUH compared to that of VUL, respectively. In contrast, lateral jumping with left (ES = 1.22) and right leg (ES = 0.49) were substantially greater in VUL than in VUH. Specific force-vector training programs induced substantial improvements in both functional performance tests and inter-limb asymmetries, although greater improvements of lateral and horizontal variables may depend on the specific force vector targeted

Adductor squeeze test and groin injuries in elite football players: A prospective study

during the competitive season of professional football teams. Design: Prospective Cohort study. Setting: Controlled laboratory environment. Participants: Seventy-one players volunteered to participate. Main outcome measures: In the pre-season, maximal hip adductor strength was measured by means of the isometric adductor squeeze test. Hip adductor strength, normalized by body mass, was compared between players who suffered a groin injury (n ¼ 18) vs uninjured players (n ¼ 53). Risk ratios (RR) were used to evaluate the likelihood of players to suffer this type of injury. Results: Most of the reported groin injuries occurred during competitive matches (5.5 per 1000 match hours). Maximal isometric hip adductor strength was lower in the groin-injured group compared with their uninjured counterparts (429.8 ± 100 vs 564 ± 58.7 N, d¼ 1.58 and 5.40 ± 1.27 vs 7.71 ± 0.89 N/kg, d¼ 1.88, respectively). Results revealed that values of maximal isometric adductor strength lower than 465.33 N increased the probability to suffer a groin injury by 72%. Furthermore, values of force relative to body mass lower than 6.971 N/kg increased the probability to suffer a groin injury by 83%. Conclusion: The assessment of Hip adductor strength, in addition to other measurements, might help practitioners to determine the probability of suffering an overuse groin injuries in elite football players.info:eu-repo/semantics/publishedVersio