•Acute resistance exercise (RE) did not increase anxiety or worry symptoms.•Acute RE responses did not change after eight weeks of RE training (RET).•Despite null effects of acute RE, trait anxiety decreased after 8 weeks of RET.•Clinicians should encourage chronic engagement in RET for maximum benefits. Background The effects of a single bout of resistance exercise (RE) on state anxiety and worry symptoms are understudied. Further, how resistance exercise training (RET) changes response to acute RE is unknown. Methods Sixty-two untrained young adults (mean age (y):26.6; RET n = 27, Wait-list (WL): n = 35, 62.9% female) were randomized to an eight-week, ecologically-valid, guidelines-based RET condition, or eight-week WL control condition. Two acute RE trials were nested within the design at week one and eight, to determine RE response, and change in RE response following RET. The RET condition completed a twice-weekly RET intervention. The WL condition completed 30-minute bouts of quiet-rest at week one and eight. Two-condition (RE/quiet-rest) x two-time (pre/post) x two-session (weeks one/eight) RM-ANCOVAs examined differences between acute RE and quiet-rest pre-post and between acute sessions. Sub-analyses were conducted among young adults with analogue-Generalized Anxiety Disorder (AGAD). Primary outcomes were anxiety and worry symptoms. Results Compliance was 99% (Rate of perceived exertion (6–20) = 14±1, Muscle soreness (1–10)=4 ± 2), with no adverse events. There were no significant three-way interactions for anxiety symptoms or worry symptoms (all p ≥ 0.51) among the total sample or AGAD sample. The magnitude of change in outcomes at each session for both samples were small and non-significant (Hedges’ d = -0.26 to 0.23). Limitations Post-condition assessment of primary outcomes was only conducted at a single time point. Conclusion RE did not elicit significant reductions in state anxiety or worry symptoms ten minutes post-RE. RET did not change response to acute RE. Clinicians should encourage RET for maximum anxiolytic benefits.