Date of Award
Ph.D. in Health and Kinesiology
Jeremy P. Loenneke
Mathew B. Jessee
Paul D. Loprinzi
University of Mississippi
Background: Baseline vascular networks or significant changes in vascular network due to resistance training may induce greater muscle growth. Evidence doesn't support a causal relationship between changes in muscle size and strength. Cross-education is observed with high-intensity/loads and adding blood flow restriction to low-intensity exercises results in greater muscle growth, strength, and resting limb blood flow.
Purpose: To investigate the effects of exercise intensity and blood flow restriction on muscle size, strength, and resting limb blood flow in both trained and untrained arms.
Methods: A total of 179 participants were randomized into: low-intensity isometric handgrip exercise (LI), low-intensity isometric handgrip exercise with blood flow restriction (BFR-LI), maximal handgrip exercise (MAX), and non-exercise control (CON). All training groups completed 18 sessions of isometric handgrip exercises over six weeks, with pre- and post-testing sessions to assess changes in muscle size, strength, and resting limb blood flow. Bayesian ANCOVA was used to compare changes. Moderation for baseline resting limb blood flow to change in muscle thickness. Two mediation analyses investigated the influence of muscle thickness on strength and resting limb blood flow on muscle thickness.
Results: Resting blood flow did not differ between groups (BF10: 0.062). Blood flow restriction led to a greater increase in muscle thickness compared to the same exercise without blood flow restriction [LI: -0.003 (SD 0.13) cm, BF10: 5.35]. Maximal handgrip strength increases the most with MAX [4.87 (SD 3.35) kg, BF10: 277537] followed by BFR-LI [2.85 (SD 4.09) kg] compared to CON [0.848 (SD 2.91) kg, BF10: 5.548]. The overall test showed that it was only BFR-LI that resulted with cross-education [CON: 0.64 (SD 2.92), LI: 0.95 (SD 3.64), BFR-LI: 2.76 (SD 3.36) MAX: 0.80 (SD 3.19), BF10: 3.44]. No moderation or mediation observed for any variables.
Conclusion: Baseline resting limb blood flow and its change did not impact muscle thickness, suggesting that growth may not have occurred to an extent that would require an expansion of the vascular network. Training maximally increased strength the greatest, supporting specificity. Training with blood flow restriction resulted in cross-education of strength, improving the limited effectiveness of isometric upper body exercise.
Wong, Vickie, "The Influence of Isometric Handgrip Exercise and Blood Flow Restriction on the Changes in Muscle Size, Strength, and Resting Limb Blood Flow in Trained and Untrained Limbs" (2023). Electronic Theses and Dissertations. 2599.
Available for download on Saturday, September 13, 2025