Author(s): OLIVA, V., ŠAŠOVOVÁ, G., KUNDEKOVÁ, B., ORESKÁ, L., STRELECKÝ, M., BUZGÓ, G., SEDLIAK, M., Institution: COMENIUS UNIVERSITY IN BRATISLAVA, FACULTY OF PHYSICAL EDUCATION AND SPORT, Country: SLOVAKIA, Abstract-ID: 2100

INTRODUCTION:
Diurnal fluctuations in muscle performance and the effects of time-of-day-specific training are well documented in young adults, but remain poorly understood in elderly women. This study investigated whether morning versus afternoon concurrent resistance-aerobic training differentially affects muscle strength, body composition, bone mass and functional performance in elderly women.
METHODS:
Twenty-six women (65–85 years) were randomized to a morning training group (MTG), afternoon training group (ATG), or control (CON). MTG and ATG completed 12 weeks of supervised concurrent resistance-aerobic training (3 sessions per week), while CON maintained usual activities. Whole-body fat mass, fat-free mass and bone mineral density were assessed by DXA. Maximal voluntary isometric knee extension (morning and afternoon tests) was measured using an isometric knee dynamometer, and functional performance was assessed by the Timed Up and Go (TUG) test.
RESULTS:
Relative knee extension torque increased in both training groups, with larger gains in ATG than MTG (MTG: +26% morning, +30% afternoon; ATG: +46% morning, +42% afternoon), whereas CON showed minimal change (+27% and +3%). Mixed-model analyses revealed a significant effect of time and group differences in strength adaptation, with ATG showing superior POST strength compared with MTG and CON (p < 0.05). A persistent diurnal pattern was observed, with higher afternoon than morning values at both PRE and POST in the training groups. TUG performance improved significantly from PRE to POST in both MTG and ATG (p < 0.001), with no difference in the magnitude of improvement between them. Fat mass, fat-free mass and bone mass parameters remained unchanged across groups.
CONCLUSION:
In conclusion, 12 weeks of time-of-day-specific concurrent resistance-aerobic training improved muscle strength and functional performance in elderly women, with afternoon training eliciting greater strength gains than morning training. The absence of changes in body composition and bone parameters suggests that longer and/or more osteogenic interventions may be required to induce measurable skeletal and body composition adaptations.