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Table 4 Study characteristics—asymmetries examined pre and post a loading protocol/task

From: The Influence of Exercise-Induced Fatigue on Inter-Limb Asymmetries: a Systematic Review

Study Subjects (Sex, age, sport) Physical load/fatigue loading protocol Measure of fatigue Task/procedure Outcome measures Asymmetry equation
Bell et al. [7] n = 40
20 M (20.9 ± 1.2)/ 20 F (21.2 ± 1.4)
Recreationally active
Exercise loading protocol based on literature: warm-up–running course––30 s wall sit–10 fast-paced two-legged vertical jumps––30 s prone plank Loading protocol was repeated until a RPE of 17 on the scale by Borg was reached Jump landings Peak vGRF, loading rate, LESS score % asymmetry: ([dominant limb – non-dominant limb]/ 1/2 [dominant limb + non-dominant limb]) × 100%
Bishop et al. [38] n = 18
18 M (16.89 ± 0.32)
Elite academy soccer players
Five Soccer matches (played for a minimum of 60 min in each match) Not measured SLCMJ, SLDJ SLCMJ: jump height, peak force, concentric impulse
SLDJ: jump height, ground contact time, RSI
Global positioning system data
Percentage difference: 100/ (maximum value) × (minimum value) × -1 + 100
Bromley et al. [16] n = 14
14 M (17.6 ± 0.5)
Elite soccer players
Single 90-min soccer match Not measured SLCMJ Jump height, peak force, eccentric impulse, concentric impulse, peak landing force, peak landing impulse Percentage difference: 100/ (maximum value) × (minimum value) × − 1 + 100
Delextrat et al. [37] n = 14
14 F (26.1 ± 4.6)
Amateur soccer players
Modified Loughborough Intermittent Shuttle Test RPE Isokinetic strength assessment Peak torque of the quadriceps, peak torque of the hamstrings, Hecc:Qcon Calculated afterwards by the authors with percentage difference: 100/ (maximum value) × (minimum value) × − 1 + 100
Radzak et al. [35] n = 20
14 M / 6 F
(20.8 ± 2.48)
No sporting background mentioned
Speed blinded exhaustive loading protocol RPE
Until volitional exhaustion
Gait analysis Kinematic data (joint angles - ankle, knee, hip), kinetic data (external joint moment - ankle, knee, hip), GRF, stiffness, spatio-temporal parameters Symmetry angle: [(45° - arctan (Xleft/Xright)/90°)] × 100%
X = the mean value for a variable on each leg
Webster et al. [36] n = 20
20 M
10 ACLR (23 ± 3)
10 CG (23 ± 2)
Engaged in sports activities weekly
Generalized loading protocol: squats 10 ×, two vertical jumps, 10 drop landings (5 right/ 5 left) (repeated several times) Fatigue was operationally defined: jump height reduced by 20% OR when the subject could no longer complete the fatigue loading protocol Squats Kinetic data (external joint moments), ground reaction force (peak vGRF) − weight-bearing symmetry, kinematic data (joint angles) Symmetry Index = [vaffected – vunaffected / ½ (vaffected + vunaffacted)] × 100
vaffected = value of the the former injured leg
vunaffected = value of the “healthy” leg
  1. ACLR anterior cruciate ligament rupture, CG control group, F female, GRF ground reaction force, Hecc:Qcon functional ratio of the peak eccentric torque of the hamstrings to the peak concentric torque of the quadriceps, LESS landing error scoring system, M male, N/A not available, RPE rate of perceived exertion, RSI reactive strength index, SLCMJ single-leg countermovement jump, SLDJ single-leg drop jumps, vGRF vertical ground reaction force