Cardiovascular And Respiratory Responses During Aquatic Rehabilitation At Different Depths Of Supine Immersion

Abstract

Aquatic Rehabilitation (AR), is used in the treatment of athletic injuries, initially in a supported supine aquatic position, before progressing to an independent vertical position. In water entry, cardiovascular and respiratory shifts are affected by, the hydrostatic pressure, the diving reflex responses, the water temperature, and vary at different positions and levels of immersion. PURPOSE: The purpose of this study was to investigate how the depth of submersion during AR at 32οC in a supine position, affects cardiovascular and respiratory function. METHODS: Seven participants (35±10 years), were subjected to two 15-min trials of AR aquatic bodywork manipulations (MKS). Subjects were supported in a supine position by the provider’s elbow under the head, and the trunk and lower legs, a) were either kept in alignment to the surface (SI) of the water with a lumbar curve support, or b) allowed to diagonally submerge to a deeper level (DI) during movements. An underwater video camera (FinepixGPS) was used for recording, and via 2-dimensional (2-D) kinematic analysis, the depth of submersion (LOGERPRO 3.8) and hydrostatic pressure, were evaluated. During the trials, respiratory rate (RR), heart rate (HR), and oxygen saturation (SO2) were measured (ApneaLink 1_218). Before and after the trials, arterial blood was drawn for gas analyses (Abbott-I-Stat) in addition to blood pressure determination. Trials were conducted in a randomized cross-over design and analyzed for dependent measures (p<0.05). RESULTS: The depth of submersion of the trunk and legs with the SI was 0.022±0.036 m versus 0.575±0.06 m with the DI. Significant differences were observed for RR, 14.42±2.29 breaths/min vs 11.34±2.42 breaths/min (p=0.03), and systolic blood pressure, 124.85±6.52 mmHg vs 109±7.00 (p=0.008), for SI and DI respectively. No significant differences were observed for oxygen saturation or any other arterial gas variables measured. CONCLUSIONS: The increase of the depth of submersion during AR significantly impacted select cardiorespiratory parameters, i.e. breathing frequency and systolic blood pressure, consistent with an increase in parasympathetic and/or decrease in sympathetic activity. Depending on pre-existing conditions this may affect the quality of clinical care during rehabilitation of the athlete.