Author Type

Graduate Student

Date of Award

Spring 4-8-2026

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

April 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 volume cycling in resistance training can elicit a skeletal muscle hypertrophy re-sensitization effect without muscle atrophy. We hypothesized that muscle size would be maintained during lower volume phases, that re-sensitization would occur following these phases, and that overall hypertrophy would be similar between cycled and constant volume conditions.

Methods: Thirty-seven trained men and women had their lower limbs randomized to either a constant volume (12 sets/week throughout) or cycled volume (alternating 4-week phases of 12 and 4 sets/week) condition for unilateral calf press training over 20 weeks. Lateral and medial gastrocnemius muscle thickness (MT), calf circumference, and estimated 10RM were assessed at baseline, four midpoints (weeks 4, 8, 12, 16), and post-intervention. Bayesian mixed-effects models were fit for each outcome individually and as a multivariate pooled hypertrophy measure standardized by baseline standard deviation (SD). Inference was based on posterior medians, 95% credible intervals (CrI), and posterior probabilities.

Results: The constant condition produced modestly greater pre-to-post hypertrophy than the cycled condition across all measures (pooled hypertrophy: 0.094 baseline SD [95% CrI: 0.023, 0.162]; posterior probability favoring constant = 99.4%). Muscle size was largely maintained during the first lower volume phase (pooled: 0.058 baseline SD [95% CrI: 0.005, 0.109]; 98.4% probability of maintenance or growth), but maintenance was less evident during the second lower volume phase (pooled: −0.017 baseline SD [95% CrI: −0.080, 0.047]; 29.6% probability of maintenance). No evidence of re-sensitization was observed; posterior probabilities favoring greater cycled improvements during higher volume phases following lower volume periods ranged from 6–67% (weeks 8–12) and 54–74% (weeks 16–20). Strength was maintained or increased in both lower volume phases (96.9–98.3% probability), and the between-condition difference was uncertain (1.762 kg [95% CrI: −2.213, 5.545]; 82.1% probability favoring constant).

Conclusions: Volume cycling did not elicit a hypertrophy re-sensitization effect, and the constant higher volume condition produced modestly greater overall hypertrophy. Muscle size was maintained during the initial lower volume phase, but evidence of maintenance weakened during the second. These findings suggest that volume reductions without substantial muscle atrophy may not restore hypertrophic sensitivity.

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