Using Heart Rate to Prescribe Physical Exercise During Head-Out Water Immersion

Abstract

The purpose of this study was to compare and correlate the effect of age group, sex, depth of water immersion, and the heart rate (HR) assessed out of the water on the HR behavior in individuals subjected to head-out water immersion. A total of 395 healthy individuals of both sexes, aged between 07 and 75 years, underwent vertical head-out water immersion. Heart rate was assessed out of the water in the supine and orthostatic (OHR) positions and at immersion depths corresponding to the ankle, knee, hip, umbilicus, xiphoid process, acromion, neck, and also the neck with the arms out of the water. The formula (ΔHR = OHR - HR immersion depth) was used to calculate the reduction in HR at each immersion depth. No age-based or sex-based differences in HR were found. The greater the depth of the water, the greater was the decrease in HR (p < 0.05); however, no differences were found between the HR values obtained below the depth corresponding to the umbilicus. Similarly, there was a significant relationship between OHR and ΔHR measured at levels below the depth corresponding to the umbilicus (e.g., xiphoid process level: r = 0.62; p < 0.05). Therefore, this study suggests to appropriately prescribe the intensity of water-based exercise intensity performed during vertical immersion: OHR should be measured before the individual entering the aquatic environment; ΔHR should be measured according to the depth at which exercise is to be performed, and we suggest an adaptation to Karvonen's HRmax prediction formula (predicted HRmax: 220 - age - ΔHR) to prescribe and control the intensity of the exercise performed during vertical immersion.

Cerebral Blood Flow Responses to Aquatic Treadmill Exercise

“…The decrease in HR associated with increasing immersion levels noted in this study is supported by previous studies that have reported a continuous decrease in HR from hip level up to head-out immersion in water at rest (4,20). Our findings illustrate that a similar elevation in MCAv mean can be achieved with greater water immersion for a comparatively lower heart rate.…”

“…Further, given the linear relation between cardiac output and CBF (26), another likely contributor to the augmented blood flow velocity is related to the well-documented increases in cardiac output during water immersion (29), due to the effects of increased hydrostatic pressure centralising blood within the trunk and increasing stroke volume (5). Interestingly, an elevated stroke volume would appear to be the key mediator of this increased cardiac output, since a reduction in HR (as we observed) during water immersion is also well documented (4,16,20). In contrast, Pugh et al (31) reported no significant difference in HR between water and land during their low-intensity exercise.…”

Aquatic High Intensity Interval Training for Cardiometabolic Health

“…[64][65][66] The same hydrodynamic properties that influence velocity of movement also affect HR responses. 67 Accordingly, traditional land-based methods to prescribe exercise intensity such as HRs or velocity are Because a human is less dense than water, the body will be individually offloaded, depending on body composition and the depth of immersion.…”

“…87 Factors such as increased water temperatures, water submersion levels, and relative workloads may also serve as aerobic and chronotropic modulators. 67,[88][89][90] Accordingly, aquatic HIIT appears to offer an effective CR stimulus when greater movement velocities are performed to overcome the hydrodynamic and increased resistive forces of water. 63,65 This has been substantiated by acute shallow-water HIIT responses >90% HR max , supporting this training modality as a bonafide stimulus to improve CR fitness.…”

Effects of land vs water jump exercise: Implications for exercise design targeting bone health

“…The maximal heart rate (HR max ) was predicted according to a previous study for land testing . Kruel et al showed that the predicted HR max should consider the reduction in HR at immersion (HR rest on land − HR rest in water = △HR). We used an adaptation of Karvonen's HR max prediction formula (predicted HR max : 208 − 0.7·age−△HR) for water testing.…”