Chronic effects of progressive moderate-to-high intensity resistance exercise training compared to a low-intensity sham on anxiety related outcomes in young women with analogue generalized anxiety disorder: A randomized controlled trial

Background: Resistance exercise training (RET) has shown promising effects on anxiety, but prior studies have overlooked mode-specific expectations, which may contradict any causal findings. Methods: This randomized controlled trial examined the effects of ten-weeks of twice weekly, progressive, moderate-to-high intensity guidelines-based RET (PRET) (70-80% of estimated one-repetition maximum (1RM); n = 27) compared to a low-intensity sham RET attention-control (SHAM) (20% 1RM; n = 28) on anxiety outcomes among fifty five young women (21.8 ± 2.5y/o) with Analogue Generalized Anxiety Disorder (AGAD). Anxiety symptoms, feelings of tension and expectations were measured at baseline, post-familiarization, week four, week eight, and four-week follow-up. A two-group (PRET/SHAM) x five time-point RM-ANOVA quantified differences between groups. Hedge's d and standardized mean difference (SMD) effect sizes quantified the magnitude of differences between and within groups, respectively. Spearman's rho quantified associations between expectations and engagement, compliance and psychological responses. Results: No significant group × time interaction was found for anxiety symptoms (F_{(2.9, 157)=}0.49, p≥0.68; d = 0.23, 95%CI: −0.30 to 0.76) and feelings of tension ((F_{(3.5, 184)} = 1.1, p≥0.34; d = 0.002, 95%CI: −0.53 to 0.53). RET significantly reduced anxiety and feelings of tension for moderate to large effect sizes for both conditions (all SMD:0.76 to 1.16). At four-weeks follow up, PRET had larger effects on anxiety and feelings of tension (SMD:1.30 and 1.22, respectively) compared to SHAM (SMD:0.84, 0.75, respectively). No significant associations were observed between baseline and changes in expectations and psychological responses (all rho: −0.16 to 0.25, all p ≥ 0.19). Conclusions: Both RET intensities significantly reduced anxiety related outcomes in young women with AGAD, independent of expectations. However, PRET produced more sustainable anxiolytic effects.