Author(s): SCHAUN, G., RAIDL, P., ANDRADE, L., DAVID, G., KRÜGER, V., MARINS, E., NUNES, G., HÄFELE, M., MENDES, G., PINTO, S., ALBERTON, C., CSAPO, R., Institution: UNIVERSITY OF VIENNA, Country: AUSTRIA, Abstract-ID: 721

INTRODUCTION:
Evaluating the effectiveness of training interventions to prevent or mitigate age-associated neuromuscular impairments typically involves diverse neuromuscular, morphological, and functional tests. Although these generally demonstrate established test-retest reliability, their reproducibility could vary depending on the age and functional status of the subjects examined. Therefore, the goal of the present investigation was to determine the test-retest reliability of some of the most frequently applied tests in middle-aged and older adults of differing functional conditions.
METHODS:
Middle-aged (n = 17, 48.7 ± 4.6 years) and older adults with (n = 18, 68.0 ± 6.2 years) and without (n = 8, 77.3 ± 7.6 years) mobility limitations were included in this study. Participants were familiarized with the study procedures and then attended two testing sessions separated by four weeks. Measures included ultrasound-derived muscle thickness (MT) and muscle quality (EI), lower limb maximal isometric (MVIC) and dynamic strength (1-RM), peak power, and a battery of seven functional tests (Short Physical Performance Battery, 30 s Sit-to-Stand, habitual and maximal gait speed, Timed Up-and-Go, Stair Climb, and 6-min Walk Test). The intraclass correlation coefficients (ICC2,1), standard error of measurement (SEM), coefficient of variation (CV%), and minimal detectable change (MDC) were determined.
RESULTS:
In the entire sample, both dynamic and isometric strength measures displayed excellent reliability (ICCs = 0.96-0.99; CV% = 6-12%), whereas ultrasound MT and EI results ranged from good to excellent (ICCs = 0.90-0.98; CV% = 5-12%). Peak power results displayed good to excellent relative reliability (ICCs = 0.76-0.98), whereas absolute reliability values varied for loads between 30-90% 1-RM (CV% = 12-39%). Finally, functional performance measures showed good to excellent reliability (ICCs = 0.78-0.92; CV% = 3.5-6.8%). When groups were analyzed separately, dynamic and isometric strength, as well as MT and EI measures showed mostly similar results between the groups (all ICC > 0.9 and CV% ≤ 13%), whereas peak power and functional tests results differed slightly on a per-load and per-test basis, respectively.
CONCLUSION:
Overall, our results suggest that the investigated tests are reliable in both middle-aged and older adults of different functional statuses. Notably, the reliability of some of these tests remained relatively consistent across distinct subsets of participants, suggesting their suitability for studies involving comparisons among these populations.