Long-Term Flywheel Resistance Training Enhances Cognitive Flexibility in Older Women: A 36-Week Randomized Controlled...

Background: Executive functions (EFs) decline with aging, impacting functional independence. While resistance training (RT) is a promising non-pharmacological intervention, the optimal modality and duration for cognitive benefits remain unclear. Flywheel RT (FRT) imposes greater motor control and attentional demands than traditional RT (TRT), potentially enhancing EFs. Objective: To compare the effects of a 36-week FRT versus TRT program on executive function and serum insulin-like growth factor 1 (IGF-1) levels in healthy older women. Methods: This parallel-group randomized controlled trial allocated 64 older women (overall mean age 66.8 ± 4.6 years; FRT group: 68.0 ± 4.8 years; TRT group: 65.5 ± 4.1 years) to either FRT (n = 25) or TRT (n = 21) for two weekly sessions over 36 weeks. Executive function was assessed using the Victoria Stroop Test (inhibitory control), Digit Span Test (working memory), and Trail Making Test (cognitive flexibility). Serum IGF-1 was quantified via chemiluminescence. Intention-to-treat analyses with ANCOVA were performed. Results: After 36 weeks, both groups showed significant within-group improvements in inhibitory control (mean reduction from pre to post: FRT: 15.2 ± 10.4 to 14.8 ± 7.4 s; TRT: 20.4 ± 11.8 to 15.6 ± 7.3 s; p = 0.028, ηp² = 0.38) and working memory (Digit Span Forward: FRT: 6.2 ± 1.7 to 7.9 ± 2.0; TRT: 6.7 ± 1.5 to 8.7 ± 1.8; p < 0.001, ηp² = 0.84). The B/A ratio of the Trail Making Test improved significantly more in the FRT group (73.0 ± 65.2 to 87.5 ± 68.1 s) compared to the TRT group (67.3 ± 54.1 to 137.7 ± 83.6 s; group × time interaction: p = 0.001, ηp² = 0.13). No significant changes in serum IGF-1 concentrations were observed in either group (FRT: 112.9 ± 25.4 to 115.3 ± 21.3 ng/mL; TRT: 104.7 ± 27.5 to 103.0 ± 28.9 ng/mL; p = 0.88, ηp² = 0.002). Adherence was high (only 4 out of 46 participants did not complete all 72 sessions), and no severe adverse events were reported. Conclusions: Flywheel training appears particularly effective for enhancing cognitive flexibility, likely due to its higher cognitive-motor demands. The absence of significant changes in circulating IGF-1 suggests that the observed cognitive benefits may not be mediated by systemic endocrine pathways, although this does not exclude the possibility of local central nervous system adaptations or changes in other neurotrophic factors not assessed in this study.