The effect of underwater massage during hot water immersion on acute cardiovascular and mood responses

Purpose: There is emerging evidence that demonstrates the health benefits of hot water immersion including improvements to cardiovascular health and reductions in stress and anxiety. Many commercially available hot tubs offer underwater massage systems which purport to enhance many benefits of hot water immersion, however, these claims have yet to be studied. Methods: Twenty participants (4 females) completed three, 30-minute sessions of hot-water immersion (beginning at 39°C) in a crossover randomized design: with air massage (Air Jet), water massage (Hydro Jet) or no massage (Control). Cardiovascular responses comprising; heart rate, blood pressure and superficial femoral artery blood flow and shear rate were measured. State trait anxiety, basic affect, and salivary cortisol were recorded before and after each trial. Data were analysed using a mixed effects model.Results: Post immersion, heart rate increased (Δ31bpm, P &lt; 0.001, d = 1.38), mean arterial blood pressure decreased (Δ16 mmHg, P&lt;0.001, d = −0.66), with no difference between conditions. Blood flow and mean shear rate increased following immersion (P &lt; 0.001, Δ362 ml/min, d = 1.20 and Δ108 s−1, d = 1.00), but these increases were blunted in the Air Jet condition (P &lt; 0.001,Δ171 ml/min, d = 0.43 and Δ52 s−1, d = 0.52). Anxiety and salivary cortisol were reduced (P = 0.003, d = −0.20, P = 0.014, d = −0.11), but did not vary between conditions. Enjoyment did not vary between conditions.Conclusion: These data demonstrate positive acute responses to hot water immersion on markers of cardiovascular function, anxiety, and stress. There was no additional benefit of water-based massage, while air-basedmassage blunted some positive vascular responses due to lower heat conservation of the water. <br/

Post exercise hot water immersion and hot water immersion in isolation enhance vascular, blood marker, and perceptual responses when compared to exercise alone

Exercise and passive heating induce some similar vascular hemodynamic, circulating blood marker, and perceptual responses. However, it remains unknown whether post exercise hot water immersion can synergise exercise derived responses and if they differ from hot water immersion alone. This study investigated the acute responses to post moderate-intensity exercise hot water immersion (EX+HWI) when compared to exercise (EX+REST) and hot water immersion (HWI+HWI) alone. Sixteen physically inactive middle-aged adults (nine males and seven females) completed a randomized cross-over counterbalanced design. Each condition consisted of two 30-min bouts separated by 10 min of rest. Cycling was set at a power output equivalent to 50% V̇o2 peak. Water temperature was controlled at 40°C up to the mid sternum with arms not submerged. Venous blood samples and artery ultrasound scans were assessed at 0 (baseline), 30 (immediately post stressor one), 70 (immediately post stressor two), and 100 min (recovery). Additional physiological and perceptual measures were assessed at 10-min intervals. Brachial and superficial femoral artery shear rates were higher after EX+HWI and HWI+HWI when compared with EX+REST (p &lt; 0.001). Plasma nitrite was higher immediately following EX+HWI and HWI+HWI than EX+REST (p &lt; 0.01). Serum interleukin-6 was higher immediately after EX+HWI compared to EX+REST (p = 0.046). Serum cortisol was lower at 30 min in the HWI+HWI condition in contrast to EX+REST (p = 0.026). EX+HWI and HWI+HWI were more enjoyable than EX+REST (p &lt; 0.05). Irrespective of whether hot water immersion proceeded exercise or heating, hot water immersion enhanced vascular and blood marker responses, while also being more enjoyable than exercise alone

The health benefits of passive heating and aerobic exercise: to what extent do the mechanisms overlap?

Exercise can induce numerous health benefits that can reduce the risk of chronic diseases and all-cause mortality, yet a significant percentage of the population do not meet minimal physical activity guidelines. Several recent studies have shown that passive heating can induce numerous health benefits, many of which are comparable to exercise, such as improvements to cardiorespiratory fitness, vascular health, glycaemic control and chronic low-grade inflammation. As such, passive heating is emerging as a promising therapy for populations who cannot perform sustained exercise or display poor exercise adherence. There appears to be some overlap between the cellular signalling responses that are regulated by temperature and the mechanisms that underpin beneficial adaptations to exercise, but detailed comparisons have not yet been made. Therefore, the purpose of this mini review is to assess the similarities and distinctions between adaptations to passive heating and exercise. Understanding the potential shared mechanisms of action between passive heating and exercise may help to direct future studies to implement passive heating more effectively and identify differences between passive heating and exercise induced adaptations