Physiological And Hormonal Responses To Cold Water Immersion Following Cycling In The Heat

Abstract

Cold water immersion (CWI) has become a popular means of enhancing recovery from various types of exercise. However, the anecdotal support and widespread usage of this technique is not reflected by rigorous scientific investigation. Indeed the mechanism/s by which CWI may enhance recovery are speculative. Purpose To examine the acute effects of CWI following intense cycling in the heat on thermoregulatory, cardiovascular, metabolic and endocrine responses. Methods Eleven male endurance trained cyclists (Age: 23.8 ± 1.6 yr; VO2max: 71.3 ± 1.2 ml.kg−1·min−1; Sum of 7 skinfolds: 49.9± 2.8 mm) completed two simulated ∼40min time trials in an environmental chamber maintained at 34.3 ± 1.1°C and 41.2 ± 3.0% RH. Following the cessation of exercise subjects were randomly allocated to either a CWI condition or a control condition (C). CWI consisted of immersion in 11.5°C water to the level of the mesosternale for 60 seconds repeated three times, with 120 seconds between exposures. In the C condition subjects sat passively in 24.2 ± 1.8°C and 45.6 ± 6.5%RH. Capillary blood samples were taken prior to and immediately following each exposure and assayed for lactate, glucose, pH and blood gases. Plasma samples were taken pre and post the complete recovery period and assayed for catecholamines, cortisol, testosterone, creatine kinase, C-reactive protein, IL-6, IGF-1. Heart rate (HR), rectal temperature (Trec) and skin temperature (Tskin) were measured throughout the recovery period. Results CWI resulted in a significantly lower HR (CWI: Δ116 ± 9 bpm vs. C: Δ106 ± 4 bpm), Trec (CWI: Δ1.99 ± 0.5°C vs. C: Δ1.49 ± 0.5°C) and Tskin and significantly increased pH in comparison to C. However all other measures were not significantly different between conditions. All eleven subjects subjectively reported enhanced sensations of recovery following CWI when compared to C. Conclusion CWI significantly reduced HR, Trec and Tskin, however indices of muscle damage, repair and inflammation were unaffected by CWI after 30 minutes of recovery. Supported by an Australian Sports Commission Grant