This study compared two methods (Limb Symmetry Index [LSI] vs Normative Values (Norm-values)) for assessing neuromotor recovery in elite soccer players after a sport-specific rehabilitation program.
Kinetic movement and muscle activation were recorded during a single-leg countermovement jump. An experimental group (EG, n=15, with various injuries) and a healthy control group (CG, n=22) performed the same tests. Comparisons were made between the injured and healthy legs in the EG (%LSI) and between the injured leg in the EG and the dominant leg in the CG (%Norm-values).
This study followedthe principles of the Declaration of Helsinki (1964), and the national ethics committee for sports science research (CERSTAPS n°IRB00012476-2020-24-03-48) approved all methodology of this study.
The Shapiro-Wilk test was used to check the normality of data distribution. Repeated measures (RM) ANOVAs included the method (3-levels: NVIL, NVNIL vs LSI) as the within subject factor were used for LSI and NV for injured and non-injured leg . Tukey post-hoc test assessed pairwise statistical differences between method conditions. The significance threshold was set at p<0.05. The effect sizes for mean values was determined by a Cohen's d (classified as trivial: <0.2, small: 0.2-0.49, medium: 0.5-0.79, and large: ≥0.8).
Post-rehabilitation, the LSI method showed mean kinetic values of 118%, while the Norm-Values method showed 87% for the injured leg and 98% for the non-injured leg. Combined EMG and kinetic values were 120% for LSI vs 88% for Norm-Values for the injured leg and 87% for the non-injured leg.
The LSI method overestimated recovery compared to the Norm-Values method, which may be more accurate for post-injury assessment. If Norm-values are unavailable, LSI can be used with caution in interpreting results.