Effect of unilateral training and bilateral training on physical performance: A meta-analysis

Abstract

Background: In Unilateral (UNI) exercises are more effective than bilateral (BI) exercises in improving athletic performance is debatable. Objectives: this meta-analysis investigated the effects of UNI and BI exercises on different effect indicators of jump ability, sprint ability, maximal force, change of direction ability, and balance ability. Data Sources: PubMed, Google Scholar, Web of science, CNKI, Proquest, Wan Fang Data. Study Eligibility Criteria: To be eligible for inclusion in the meta-analysis, the study had to be: 1) athletes; 2) UNI training and BI training; 3) the intervention period had to be more than 6 weeks and the intervention frequency had to be more than 2 times/week; 4) the outcome indicators were jumping ability, sprinting ability, maximum strength, and change of direction and balance. Study Appraisal and Synthesis Method: We used the random-effects model for meta-analyses. Effect sizes (standardized mean difference), calculated from measures of horizontally oriented performance, were represented by the standardized mean difference and presented alongside 95% confidence intervals (CI). Results: A total of 28 papers met the inclusion criteria, and Meta-analysis showed that UNI training was more effective than BI training in improving jumping ability (ES = 0.61.0.23 to 0.09; Z = 3.12, p = 0.002 < 0.01), sprinting ability (ES = -0.02, -0.03 to -0.01; Z = 2.73, p = 0.006 < 0.01), maximum strength (ES = 8.95,2.30 to 15.61; Z = 2.64, p = 0.008 > 0.05), change of direction ability (ES = -0.03, -0.06 to 0.00; Z = 1.90, p = 0.06 > 0.01) and balance ability (ES = 1.41,-0.62 to 3.44; Z = 1.36, p = 0.17 > 0.01). The results of the analysis of moderating variables showed that intervention period, intervention frequency and intervention types all had different indicators of effect on exercise performance. Conclusion: UNI training has a more significant effect on jumping and strength quality for unilateral power patterns, and BI training has a more significant effect on jumping and strength quality for bilateral power patterns.

Keywords: ability; bilateral exercises; explosive power; maximal force; unilateral exercises.

FIGURE 1

Flowchart for inclusion and exclusion of studies.

FIGURE 2

Intergroup Forest plots of UNI and BI training affecting Maximal Force. RESS = rear elevated split squat; LS-L = lunge squat with left leg; LS-R = lunge squat with right leg; BLD = bended-leg deadlift; BS = Bulgarian Squat; RD = Romanion deadlift; SLRD = Single-Leg Romanion deadlift.

FIGURE 3

Intergroup Forest plots of UNI and BI training affecting jumping ability. CMJ = countermovement jump; CMJ-L = countermovement jump with left leg; CMJ-R = countermovement jump with right leg; CMJd = countermovement jump with dominant leg; CMJnd = countermovement jump with non-dominant leg; CMJ-S = countermovement jump with single leg; SLJ = standing long jump; SLJ-L = standing long jump with left leg; SLJ-R = standing long jump with right leg; SLJd = standing long jump with dominant leg; SLJnd = standing long jump with non-dominant leg; SLJ-S = standing long jump with single leg; VJ = vertical jump; VJ-L = vertical jump with left leg; VJ-R = vertical jump with right leg; VJd = vertical jump with dominant leg; ARTH-D = assisted running double feet touch high; ARTH-S = assisted running single foot touch high; HRJ = highest reach jump; HRJ-S = highest reach jump with single leg; HC3J = cross and horizontal triple jump; H3J = horizontal triple jump; H3J-R = horizontal triple jump with right leg; H3Jd = horizontal triple jump with dominant leg; H3Jnd = horizontal triple jump with non-dominant leg; HJ-L = horizontal jump with left leg; HJ-R = horizontal jump with right leg; TARTH = three-step assisted running touch high; H3CMJ = triple bilateral horizontal jump with arm swing; HCMJ = bilateral horizontal jump with arm swing; CVJ = countermovement vertical jump; CVJ-L = countermovement vertical jump with left leg; CVJ-R = countermovement vertical jump with right leg; SJ = squat jump; SJd = squat jump with dominant leg; SJnd = squat jump with non-dominant leg; OARTH = one-step assisted running touch high.

FIGURE 4

Intergroup Forest plots of UNI and BI training affecting sprinting ability.

FIGURE 5

Intergroup Forest plots of UNI and BI training affecting Change of Direction Ability. 505-L = 505 change-of-direction speed test with left leg; 505-R = 505 change of direction speed test with right leg; COD = change-of-direction test; Pro = pro-agility test; COD180 = time in 5 + 5 m sprint change of direction of 180°; COD180d = time in 5 + 5 m sprint change of direction of 180° with dominant leg; COD180d = time in 5 + 5 m sprint change of direction of 180° with non-dominant leg; COD90d = time in 5 + 5 m sprint change of direction of 90° with dominant leg; COD90d = time in 5 + 5 m sprint change of direction of 90° with non-dominant leg; COD-L = change-of-direction test with left leg; COD-R = change-of-direction test with right leg; Illinois = Illinois test; V-cut = 25-m sprint with 4 changes of direction of 45°; C10-L = 10 m with left leg with a COD of 180°; C10-R = 10 m with right leg with a COD of 180°; C20-L = 20 m with left leg with a COD of 180°; C20-R = 20 m with right leg with a COD of 180°; C25-L = 25 m with left leg with a COD of 180°; C25-R = 25 m with right leg with a COD of 180°; t-test = T-figure route agility test; t-test = T-figure route agility test with dominant leg; t-test = T-figure route agility test with non-dominant leg.

FIGURE 6

Intergroup Forest plots of UNI and BI training affecting Balance Performance. YBT-LC = Y-Balance test of left comprehensive; YBT-RC = Y-Balance test of right comprehensive; YBT-LBM = Y-Balance test of left back middle; YBT-LBO = Y-Balance test of left back outer; YBT-LF = Y-Balance test of left front; YBT-RBM = Y-Balance test of right back middle; YBT-RBO = Y-Balance test of right back outer; YBT-RF = Y-Balance test of right front; SEBT-LB = star excursion balance test in the left posterior-lateral direction; SEBT-LF = star excursion balance test in the left anterior direction; SEBT-RB = star excursion balance test in the right posterior-lateral direction; SEBT-RF = star excursion balance test in the right anterior direction.