Reference values for fatigued versus non-fatigued limb symmetry index measured by a newly designed single-leg hop test battery in healthy subjects: a pilot study

Abstract

PurposeThere is sparse evidence for return to sport criteria after knee injury. Functional performance deficits, particularly in fatigued muscular condition, should be verified prior to the attempt to return to high-risk pivoting sports. The purpose of this study was to generate reference values for the limb symmetry index (LSI) of healthy subjects in fatigued and non-fatigued muscular condition in a newly designed test battery.MethodsForty-two healthy subjects [22 females, 20 males; mean (SD) age 30.4 (6.6) years] were evaluated using a test battery consisting of an isometric strength test, a series of five single-leg hop tests and an integrated fatigue protocol. Subjective physical activity was assessed with the Tegner Activity Scale (TAS). The cut-off values for healthy subjects were calculated considering the fifth percentile as the minimum reference value for the LSI and single-leg hop distance.ResultsThe mean (SD) overall LSI was 98.8% (4.6). No significant gender or age specific differences in limb symmetry were observed. The comparison of the non-fatigued LSI with the overall LSI revealed no clinically relevant change due to muscular fatigue. Repeated measures ANOVA revealed a significant within effect on fatigue/non-fatigue condition (F (1,38) = 18.000; p < 0.001, η 2 = 0.321) on absolute single-leg hop distance. Moreover, a significant between effect on the TAS-parameter (F (1,38) = 5.928; p = 0.020, η 2 = 0.135 between: TAS ≤ 5/TAS > 5) and on gender (F (1,38) = 23.956; p < 0.001, η 2 = 0.387) could be detected.ConclusionsThe absolute jumping distance in the single-leg hop for distance was significantly reduced due to fatigue. No clinically relevant effect of muscular fatigue was observed on limb symmetry in our study sample. Gender and physical activity are important factors to be considered when interpreting reference values.Electronic supplementary materialThe online version of this article (10.1007/s11332-017-0410-5) contains supplementary material, which is available to authorized users.

Functional performance testing and return to sport criteria in patients after anterior cruciate ligament injury 12–18 months after index surgery: A cross-sectional observational study

“…To assess functional performance, all subjects had to perform a test battery with an integrated fatigue element according to a standardized protocol. 13…”

“…Cut-off values are categorized by sex and subjective level of physical activity (TAS ≤5 and TAS >5). 13…”

“…To determine whether a subject met RTS criteria, we compared both LSI and absolute jumping distances with suggested minimum reference values from healthy subjects. 13 To identify whether scores from subjective self-administered questionnaires Depending on the variable, chi-square or independent t test were used to determine differences in the subjects' characteristics for those undergoing ACL primary repair (IB) vs. ACL AI reconstructive surgery. The sample size resulted from the strict inclusion criteria in the IB group.…”

“…The diagnostic battery which is used in this study for testing of functional performance has been evaluated previously in a group of 42 healthy subjects with no history of knee trauma, and data from the healthy population were used to generate minimum reference values as return to sport (RTS) criteria. 13 . The integrated fatigue protocol is considered important, as testing in state of muscular fatigue may reveal higher informative value for the evaluation of functional performance.…”

“…for maximum two minutes, or until the person was unable to perform further squat lunges); and a fatigued SLHD. A detailed descriptionincluding photos of the items of the test battery can be found in the supplementary material to the authors' previous publication 13.…”