Author(s): SEDLIAK, M., TOKARZ, J., HAID, M., HILLER, K., MORE, T., STÜBL, S., STARK, C., LASSNIG, A., ORESKA, L., OKULIAROVA, M., ZEMAN, M., OLIVA, V., KUNDEKOVA, B., DYAR, K., Institution: FACULTY OF PHYSICAL EDUCATION AND SPORTS COMENIUS UNIVERSITY, Country: SLOVAKIA, Abstract-ID: 2006

INTRODUCTION:
Recent findings suggest that, in older adults, resistance exercise performed in the morning may promote greater skeletal muscle hypertrophy than equivalent training conducted later in the day. This temporal pattern appears to differ from that reported in younger populations. The purpose of this study was to examine time-of-day–dependent adaptations to resistance training in older individuals, with particular emphasis on skeletal muscle and plasma lipidomic profiling.
METHODS:
Twenty-eight previously untrained older adults (20 women and 8 men; 65–75 years of age) were allocated to either a morning training group (MT, n = 14) or an afternoon training group (AT, n = 14). Both groups completed the same 12-week resistance training protocol, performed at two distinct times of day: 8:00–9:00 AM for MT and 4:00–5:00 PM for AT. Assessments conducted before and after the intervention included physical performance testing, body composition analysis, bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA). Targeted shotgun lipidomics were performed on fasting morning blood plasma and skeletal muscle samples from the vastus lateralis. A non-exercising control group was also part of the broader study but is not described for the lipidomic profile in the present report.
RESULTS:
Isometric knee extension muscle strength increased significantly in both training groups, however, the AT improved significantly more compared to MT. Resistance training did not elicit notable changes in total lean mass or bone mineral density. In skeletal muscle tissue, 1014 lipids were found. Training increased several types of lipids. Profound changes were found if cardiolipin. Time-dependent changes in lipid turnover (Triglyceride-Free Fatty Acid cycle) were found in plasma lipid classes.
CONCLUSION:
These preliminary findings suggest that time-of-day-specific resistance training induces distinct changes in plasma and skeletal muscle lipids and muscle strength.
The study was supported by the Slovak Research and Development Agency (grant no. APVV-21-0164).