Author Type

Graduate Student

Date of Award

Summer 5-12-2026

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

July 2026

Department

Biological Sciences

College Granting Degree

Charles E. Schmidt College of Science

Department Granting Degree

Biological Sciences

Degree Name

Doctor of Philosophy (PhD)

Thesis/Dissertation Advisor [Chair]

Michael C. Zourdos

Abstract

Purpose: This study examined whether autoregulation (AR) of set volume led to different hypertrophy outcomes compared to following a fixed training program. We hypothesized that AR would lead to superior hypertrophy. Further, we examined relationships between various subjective feedback metrics and hypertrophy in an exploratory fashion.

Methods: Thirty-four trained men and women had their upper limbs randomized to either an AR condition (AUTO) or a fixed condition (FIX) for unilateral biceps curl training over 10 weeks. Biceps muscle thickness (MT) and upper arm circumference (AC) were assessed at baseline, four midpoints, and post-intervention. Data were analyzed using a mediation framework to isolate the direct effect of condition on each outcome from the mediating effect of volume, using a combination of linear mixed effects models and marginal structural models with inverse probability weighting to handle time-varying confounders. Further mixed models were fit to examine relationships between subjective feedback metrics and hypertrophy.

Results: Both conditions experienced significant increases in MT (AUTO = +0.216 cm, 95% CI [0.137, 0.295], FIX = +0.222 cm, 95% CI [0.125, 0.319]) and AC (AUTO = +0.254 cm, 95% CI [-0.041, 0.548], FIX = +0.140 cm, 95% CI [-0.126, 0.406]). The direct effect of condition was not statistically significant for either ΔMT (p = 0.993) or ΔAC (p = 0.299). Further, no significant differences were observed between conditions for total set volume (p = 0.130), readiness indicators (p = 0.935-0.999), or session-rating of perceived exertion (sRPE) (p = 0.218). Relationships between hypertrophy measures and perceived muscle swelling (p = 0.379-0.860), soreness (p = 0.304-0.761), and sRPE (p = 0.313-0.799) were all non-significant.

Conclusions: Set volume AR did not lead to significant differences in measures of hypertrophy, total volume performed, or indicators of subjective experience. While AR may not have improved outcomes, it also did not hamper them, therefore it may be viewed as simply another viable strategy to reach similar outcomes.

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