Load release balance test under unstable conditions effectively discriminates between physically active and sedentary young adults

•Reliability of parameters of the load release balance test is good to excellent.•Unexpected postural perturbations and unstable conditions differentiate between groups.•The test differentiates physically active and sedentary adults from 19 years of age.•These differences are not evident when the test is performed under stable conditions.•Lack of vision fails to improve differentiation between groups under both conditions.

This study investigates test-retest reliability and diagnostic accuracy of the load release balance test under four varied conditions. Young, early and late middle-aged physically active and sedentary subjects performed the test over 2 testing sessions spaced 1 week apart while standing on either (1) a stable or (2) an unstable surface with (3) eyes open (EO) and (4) eyes closed (EC), respectively. Results identified that test-retest reliability of parameters of the load release balance test was good to excellent, with high values of ICC (0.78–0.92) and low SEM (7.1%–10.7%). The peak and the time to peak posterior center of pressure (CoP) displacement were significantly lower in physically active as compared to sedentary young adults (21.6% and 21.0%) and early middle-aged adults (22.0% and 20.9%) while standing on a foam surface with EO, and in late middle-aged adults on both unstable (25.6% and 24.5%) and stable support surfaces with EO (20.4% and 20.0%). The area under the ROC curve >0.80 for these variables indicates good discriminatory accuracy. Thus, these variables of the load release balance test measured under unstable conditions have the ability to differentiate between groups of physically active and sedentary adults as early as from 19 years of age.

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