Added effects of dual-task water-based exercise on global cognition and physical performance in older women: a three-arm randomized controlled trial.

Introduction: Dual-task water-based exercise has been proposed to enhance attention and executive functions and yield cognitive benefits beyond conventional aquatic aerobics exercise. However, evidence remains limited and heterogeneous, as few randomized controlled trials have directly compared dual-task aquatic interventions with conventional aquatic program of equivalent dose in older women. Methods: This three-arm, parallel-group, superiority randomized controlled trial was conducted in Porto Alegre, Brazil, at ESEFID/UFRGS. Older women were allocated to: dual-task water-based exercise (WEDT), conventional water-based exercise (WE), or a non-exercise control group (CG). The intervention lasted 14 weeks (2 sessions/week). Global cognition (MoCA total score) was the primary outcome. Secondary outcomes included specific cognitive measures, mobility (Timed Up and Go [TUG] and dual-task TUG [TUG-DT]), aerobic capacity, muscular performance, maximal voluntary isometric contraction (MVIC), and rectus femoris and vastus lateralis electromyographic activity (EMG). Outcomes were assessed at baseline and post-intervention. Intention-to-treat analyses used generalized estimating equations (GEE) with Bonferroni Results: Of 186 individuals screened, 67 were randomized (WEDT n=23; WE n=23; CG n=21). Mean attendance in ITT was 55.2% ± 10.36% (WEDT) and 65.7% ± 9.89% (WE), and no intervention-related adverse events were reported. In ITT, MoCA total score showed no main effects of time or group and no group×time interaction (p>0.05); among MoCA domains, only orientation showed a main effect of time (p=0.006). Semantic verbal fluency showed a significant group×time interaction (p=0.003), increasing in WEDT, decreasing in WE, and remaining stable in CG. TUG showed no significant effects (p>0.05), whereas TUG-DT showed a significant group×time interaction (p=0.032), driven by improvements in CG. A significant main effect of group was observed for the 6-min walk test (p=0.020). Neuromuscular outcomes showed significant group×time interactions for handgrip strength (p=0.037; increases in WE), MVIC (p=0.014), and rectus femoris activation (p=0.028). Conclusions: In older women, adding periodized dual-task demands to aquatic aerobics did not provide consistent incremental benefits for global cognition, while physical effects were modest and heterogeneous. These findings should be interpreted considering the moderate adherence and reduced intervention dose actually received; future trials should evaluate higher training doses and strategies to enhance adherence and monitoring. Trial registration: RBR-4tzrdjz.