Purpose: Despite a general lack of understanding of the underlying mechanisms, cold-water immersion (CWI) is widely used by athletes for recovery. This study examined the physiological merit of CWI for recovery from high-intensity exercise, by investigating if the placebo effect is responsible for any acute performance or psychological benefits.
Methods: Thirty males (mean +/- SD; age 24 +/- 5 y; V[Combining Dot Above]O2peak 51.1 +/- 7.0 mL[middle dot]kg-1[middle dot]min-1) performed an acute high-intensity interval training (HIT) session, comprised of 4 x 30-s sprints, immediately followed by one of three 15-min recovery conditions; CWI (10.3 +/- 0.2[degrees]C), thermo-neutral water immersion placebo (TWP; 34.7 +/- 0.1[degrees]C) or thermo-neutral water immersion control (TWI; 34.7 +/- 0.1[degrees]C). An intramuscular thermistor was inserted during exercise and recovery to record muscle temperature. Swelling (thigh girth), pain threshold/tolerance, interleukin-6 concentration, and total leukocyte, neutrophil, and lymphocyte count were recorded at baseline, post-exercise, post-recovery, and 1, 24 and 48 h post-exercise. A maximal voluntary isometric contraction (MVC) of the quadriceps was performed at the same time-points, with the exception of post-exercise. Self-assessments of readiness for exercise, fatigue, vigour, sleepiness, pain, and belief of recovery effectiveness were also completed.
Results: Leg strength following the MVC, and ratings of readiness for exercise, pain and vigour, were significantly impaired in TWI compared with CWI and TWP, which were similar to each other.
Conclusion: A recovery placebo administered after an acute HIT session is superior in the recovery of muscle strength over 48 h as compared with TWI, and as effective as CWI. This can be attributed to improved ratings of readiness for exercise, pain and vigour, suggesting that the commonly-hypothesised physiological benefits surrounding CWI are at least partly placebo related.
(C) 2014 American College of Sports Medicine