Post-exercise effects of cold water immersion and contrast water therapy-Part 1: Acute effects of cold water immersion and passive recovery on the physical and haematological parameters in male university rugby players over a 48-hour recovery period

Cold water immersion (CWI) is a popular recovery modality used in the sporting arena. However, there are discrepancies in the results regarding the post-exercise effects of CWI over a 48-hour recovery period. Therefore, the objective of this study was to determine the post-exercise effects of CWI and passive recovery (PAR) on the physical and haematological parameters of male university-level rugby players over a 48-hour recovery period. A cross-sectional, pre-posttest experimental study design with convenience sampling was used. Six haematological [blood lactate (BLa-), partial O2 pressure (PO2), blood glucose, sodium (Na+), haematocrit and haemoglobin] and four physical parameters (vertical jump test (VJT) -height, VJT-speed and VJT-power as well as grip strength) were evaluated at baseline, after a 15-minute fitness session, and at 0, 24 and 48 hours post-recovery in 23 male university rugby players. The CWI group sat in a cold water pool (8°C) for 20 minutes whereas the PAR group remained seated in a laboratory. At 0 hours post-CWI, BLa-, Na+ and haemoglobin returned to baseline values whereas VJT-height decreased compared to post-PAR values which improved. From 0 to 24 and/or 48 hours, PO2, VJT-height, plasma glucose, and Na+ significantly increased (p ≤ 0.05) in either and/or both groups. Significant intragroup differences (p ≤ 0.05) were noticed for BLa- and grip strength at 0 and 24 hours. VJT-height, -speed and -power were worse at 0 hours post-CWI compared to PAR. However, CWI was superior over 24 hours post-recovery to improve haemoglobin, haematocrit, Na+ and grip strength. Therefore, in cases where recovery over a longer period is required (48 hours), CWI is superior compared to PAR to restore the body’s physiological parameters and enhance recovery.