Local heating and cooling with isometric exercise training as a strategy to improve size and performance

The purpose of this study was to explore the effects of local heating and cooling with isometric exercise training of upper arm and forearm. College-aged (n=12; 21±1 y) volunteers performed 4-wk isometric exercise training of the non-dominant arm (upper arm, isometric bicep curl; forearm, handgrip), while the dominant arm served as the control. Training was performed 3x/wk and consisted of 1 set of isometric handgrip and bicep curl until volitional exhaustion at 60% pre-training MVC for the forearm (handgrip) and 1RM for the upper arm (bicep curl). Randomized ordering of heating (40°C; 15 min) and cooling (12°C; 15 min) preceded each training session. Indirect assessment of muscle size (fat-free cross-sectional area [FFCSA]) was made before and after the training period via skin fold and limb circumference measures. Biceps 1RM increased significantly (p < 0.05) after the intervention in both conditions (trained: +6%; control: +7%), whereas only the control arm increased time to fatigue (+40%; p < 0.05). FFSCA of the upper arm remained unchanged (p>0.05) in both conditions. An effect of time was noted for forearm MVC (+8%; p < 0.05), while both groups increased (p < 0.05) time to fatigue (trained: +82%; control: +64%). A trend toward an effect of time was also noted for FFCSA of the forearm (+3%; p <.10). While the intervention employed here led to many notable adaptations, the thermal stress did not appear to exert a clear benefit. Coupled with the practicality and feasibility, improving size and performance in such a short time frame has therapeutic and ergogenic aid implications.