Electronic Theses and Dissertations

Date of Award

1-1-2025

Document Type

Dissertation

Degree Name

Ph.D. in Health and Kinesiology

First Advisor

Jeremy Loenneke

Second Advisor

Paul Loprinzi

Third Advisor

Matthew Jessee

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

Purpose: To 1) examine the effects of low-load submaximal resistance exercise with blood flow restriction (BFR) on muscle size, strength, cross-education, and local muscular endurance while accounting for proximity to failure under restriction, and 2) determine whether changes in muscle size and strength differ based on the amount of muscle recruited during the exercise bout.

Methods: A total of 177 (18–35 years) participants were randomly assigned to one of five groups: unilateral low-load submaximal elbow flexion exercise 1) with BFR (LL+BFR, n=35), 2) without BFR (i.e., matched for a % of repetition-to-failure under restriction) (LL, n=37), 3) to failure (LL-Failure, n=36), 4) to failure and low-load knee extension exercise to failure (LLFailure+ Legs, n=33), and 5) a time-matched non-exercise control (CON, n=36). All exercise groups completed 18 training sessions (6 weeks). The submaximal groups performed two sets of bicep curl exercise with (80% of arterial occlusion pressure) or without BFR. The repetitions completed were based on the muscular endurance performance test with BFR during the pretesting visit. The LL-Failure group performed two sets to failure. The LL-Failure+Legs group followed the same protocol as the LL+Failure group, with each leg additionally completing four sets of knee extension exercise to failure (20 – 30 RM). The prescribed load was maintained throughout the training (30% 1RM). Muscle thickness, maximal strength, and muscular endurance were measured at pre- and post-testing. Changes were compared using Bayes Factors for Informative Hypotheses (BAIN). The ANCOVA function of BAIN was used with the pre-values serving as the covariate. Specific hypotheses were evaluated by comparing Bayes Factors and the posterior probabilities between models.

Results: Low-load submaximal exercise with BFR augmented the changes in muscle thickness (0.14 cm) compared to the same exercise without BFR (0.06 cm), and these changes were comparable to exercise performed to failure (0.17 cm). Changes in 1RM strength were greater in LL+BFR (0.54 kg), LL (0.45 kg), and LL-Failure (0.34 kg) compared to CON (-0.36 kg). However, no differences were observed between training groups. There was no evidence for cross-education of strength with the null model being the most likely (posterior probability of 0.80). Changes in muscular endurance under restriction were greatest in LL-Failure (16.5 reps), followed by LL-BFR (10.0 reps), LL (4.2 reps), and CON (-0.03 reps). Performing additional leg exercise within a given training session did not attenuate muscle growth (0.19 cm) compared with a group only performing arm exercise to failure (0.18 cm). Changes in 1RM strength also did not differ between training groups (0.32 and 0.25 kg for LL-Failure and LL-Failure+Legs, respectively).

Conclusion: At submaximal intensity, the application of BFR augmented muscle growth adaptations and these were comparable to exercise performed to failure. Increases in maximal strength were not dependent upon the application of BFR nor the proximity to failure. Greater adaptations in local muscular endurance occurred for those who trained similar to how testing was performed. There was no evidence for competition of adaptations in muscle size and strength.

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