The role of physical activity levels in retaining high-speed resistance training effects on body composition: a 1-year follow-up in older adults

Abstract Purpose This study evaluated the influence of physical activity (PA) on the retention of body composition effects achieved through a 16-week high-speed resistance training (HSRT) program over a 1-year follow-up period. Methods Forty independent older adults participated in the supervised 16-week HSRT program. After the intervention ended, participants were encouraged to maintain high PA levels. At the 1-year follow-up, 36 participants completed the assessments and were divided into the light activity group (LAG, N = 20, age 70.00 ± 3.66 years) and the moderate-to-vigorous activity group (MVAG, N = 16, age 68.50 ± 2.09 years). Body composition (InBody ® S10), PA levels (International Physical Activity Questionnaire), and anthropometric measurements were assessed at four time points. Results Significant time effects were observed for several body composition parameters over the 1-year follow-up period, with large effect sizes. Specifically, MVAG revealed significant declines in weight ( p = 0.002, d unb = −0.22), body mass index ( p = 0.002, d unb = −0.30), and fat mass (%) ( p = 0.028, d unb = −0.30) from post-intervention to the 1-year follow-up. Conversely, LAG demonstrated significant reductions in fat-free mass ( p = 0.018, d unb = −0.14), muscle mass ( p = 0.010, d unb = −0.15), and lean mass ( p = 0.014, d unb = −0.14) from pre-intervention to the 6-month follow-up ( p < 0.001, d unb = −0.18), with body cell mass also presenting significant declines from post-intervention to the 1-year follow-up ( p = 0.035, d unb = −0.13). Despite an overall decline, PA remained relatively higher than pre-intervention, particularly for total weekly activity (minutes) and energy expenditure from moderate-to-vigorous PA. Conclusions This study highlights the benefits of engaging in at least moderate PA activities for retaining the effects achieved on a previous exercise program, particularly reductions in fat mass.