Cellular, molecular and physiological effects of post-resistance exercise cold water immersion: Implications for subsequent perofrmance

Abstract

The objective of this thesis was to examine the efficacy of cold water immersion as a recovery therapy after resistance exercise. To achieve this objective, the research had two distinct aims, (1) to investigate how cold water immersion influences acute (short-term) physiological and performance responses following a single bout of resistance exercise, and (2) to investigate how regular (longer-term) use of cold water immersion following resistance training sessions may effect training-induced adaptation. Recovery following resistance exercise is a complex, multi-faceted process that can involve the combination of a variety of recovery therapies, all with the common goal of restoring physiological and psychological homeostasis. The timing of subsequent exercise bout(s) and the desired outcome from the preceding exercise bout will heavily determine the recovery duration, and whether emphasis is placed upon a single recovery therapy over another. Cold water immersion is a popular post-exercise recovery therapy with extensive use worldwide, largely due to its simplicity, and cost-effective nature of implementation. However, the use of cold water immersion is largely supported only by anecdotal evidence from athletes and practitioners. Little physiological evidence is available as to its mechanisms of action following exercise, both in acute, and long term settings. There is a paucity of physiological knowledge available regarding post-exercise cold water immersion per se, and this is accompanied with a disparity in the reported physiological and performance responses. The degree of disparity can be attributed not only to the use of cold water immersion protocols differing in e.g. temperature (5 – 15 degrees celcius), duration (5 – 20 min), immersion depth (individual limb(s) compared with whole-body) and application frequency (single compared with multiple post-exercise immersions), but also to exercise protocols with varied degrees of ecological validity. In a first experimental study, detailed in chapter 2, I investigated how a bout of active recovery (stationary, low-intensity cycling) compared with a 10 min bout of CWI at 10 degrees celcius performed after a single high-intensity resistance training session in influencing physiological and performance responses over a 6-hour recovery period. Large physiological responses were observed over the initial period of recovery that could be attributed to a decrease in central (cardiac output) and peripheral (muscle artero-venous) blood flow following cold water immersion. Despite such physiological responses, participants were able to perform more work during a resistance exercise training simulation exercise when cold water immersion was used. Therefore, a second experimental study, detailed in chapter 3 was undertaken to more closely investigate how performing cold water immersion or active recovery after resistance exercise influence physiological responses over the initial 60 min following the recovery therapy, and how these physiological responses correspond with exercise performance. This study identified marked effects of cold water immersion upon physiological responses such as cardiac output and muscle tissue oxygenation. However, similar to the first study, resistance exercise performance was not impaired following the use of cold water immersion. These two experimental investigations identified that acutely, a single bout of cold water immersion post-exercise can induce significant and lasting physiological responses. In a chronic environment, such responses could have detrimental effects on adaptation. However, from a performance perspective, resistance exercise performance was maintained, and to some extent improved following cold water immersion. Chronic use of cold water immersion within a training environment may therefore promote greater adaptation, by enhancing recovery between training sessions, and consequently promoting performance within subsequent sessions. To investigate the effects of regular cold water immersion on adaptation, and the acute cellular and molecular responses to cold water immersion performed after resistance exercise, two further investigations were conducted, which are detailed in chapter 4. These studies involved (1) a 12-week period of resistance training, and (2) an acute bout of resistance exercise, where acute cellular and molecular anabolic responses were assessed from 2-48 hours post-exercise. In both studies, responses were compared between conditions performing either cold water immersion or active recovery post exercise. The use of cold water immersion significantly reduced strength and hypertrophy adaptation to resistance training, and also augmented the anabolic response. Taken together, the data generated by these investigations suggest that the acutely, post-exercise cold water immersion may be beneficial in maintaining or enhancing performance undertaken 20 min to 6 hours following resistance exercise, despite marked physiological responses. However, importantly, when cold water immersion is used within a resistance training environment, the accumulation of these acute physiological responses and/or an augmented anabolic response may explain a large inhibition of adaptation that exists. Therefore, the use of cold water immersion as a recovery therapy should be periodised based on the desired outcome of the preceding exercise bout. Cold water immersion may be used when the desired outcome is optimal performance and recovery, however its use should be carefully considered when exercised-induced stress for the promotion of adaptation is desired.