Hot Immersion's Effect On Heart Rate: A Bioscience Essay On The Human Body." (70 Characters)

Effects of Hot Water Bathing on the Human Body

Describe about the Bioscience for Studied for Human Body .

Effects of hot water bathing were well studied on the human body including heart rate. Hear rate is under the influence of numerous homoeostatic mechanisms. In the literature it has been mentioned that around 10 % sudden deaths occur due to the hot water bath and out of these deaths 10 % were due to cardiovascular problems. Physiologic and metabolic processes of human beings get affected by temperature changes. Acute and chronic changes in temperatures have significant effect on the physiological processes like heart rate. Due to hot water bath, there can be increased skin temperature. Due to this increase in the skin temperature sweating occurs and it results in the increased vasoconstriction and shivering. Very low frequency power (0.0039-0.04 Hz) raised in response to vasoconstriction and shivering.

 With the increase in the internal body temperature due to hot water, blood vessel dilates. As a result heart has to pump at faster rate to maintain adequate blood pressure allowing blood to cool down. Heart rate recovers to the normal state from its increased state upon removal from the hot water because there is the core hypothermia (Kamath and Adrian, 2016; Vrijkotte et al, 2000). Tabara et al., (2004) conducted study on eight elderly female and eight young women to study effect of hot immersion at 40°C for 10 minutes. In this study they observed that high frequency (0.2 Hz) and low frequency (0.1 Hz) heart rate significantly increased from the baseline in both elderly and young women. They concluded that, variability in the heart rate is due to the alteration in the autonomic nervous system.   

Taheri et al., (2012) studied effect of warm water in 13 female students on heart rate. These female students walked through the warm water. They observed that, there is increased heart rate in these female students after walking through warm water.

In these two studies, water temperature is little higher as compared to our planned experiment. In our study, hand and forearm are going to be immersed in the hot water, however in the above mentioned studies whole body was immersed and walking was performed in the hot water. As planned study is different in design from the mentioned studies, we are expecting new information from our planned study.

The aim of the experiment is to study effect of hot immersion (37°C) of both the hands on the heart rate.

Physiological and Metabolic Processes Affected by Temperature Changes

It is hypothesized that immersion of both the hands in warm water (37°C) will increase in heart rate and.

In this experiment 6 male healthy subjects were included in the study  with age between 18-20. All the subjects reported to not have been on any type of medication in the last 6 months. These subjects didn’t report any type of allergy.

Materials used in this experiment were stopwatch (Clark), large bucket, Thermometer 0 to 100 °C (Miller) and kettle. Heart rate (HR) was measured with an automatic digital sphygmomanometer (HEM-808F, OMRON Co, Tokyo, Japan).

Subjects were relaxed for five minutes and after that heart were measured. Bucket was filled with warm water at 37°C temperature and maintained this temperature throughout the experiment by adding hot or cool water. Subjects submerged their hands in the warm water up to their elbow. After 10 minutes heart rate was measured using automatic digital sphygmomanometer for all the subjects. Subjects kept their hands in water after measurement to take measurement at 20 and 30 minutes.

For the obtained data, descriptive statistics in the form of mean and standard deviation was used. Also inferential statistics ‘t’ test was used.

Results: It was observed that heart rate after immersion of hand in warm water at 37°C increased with increase in time of immersion as compared to the heart rate at the start of experiment (Table 1; Figure 1

 Table 1: Time dependent effect of immersion in warm water on heart rate.

Figure 1: Heart rate measurement of 6 subjects. 

These findings were consistent with our hypothesis and the previous studies in which due to warm water there is the increase in the heart rate (Tabara et al., 2004; Taheri et al., 2012). Magnitude of increase in heart rate is similar to the previous studies because there is not much temperature difference. Heart rate variability observed across the subjects was consistent however, inter-subject variation has been observed. It has been observed that core temperature increase and highest increase in heart rate was observed during the later period of immersion.     

Taheri et al., (2012) studied effect of walking in warm water on heart rate. They found that heart rate was increased in stepwise manner from cold, mild and warm water. There was also decrease in the both systolic and diastolic blood pressure with increase in temperature. Blood pressure is more in cold water as compared to mild and warm water. This decrease in blood pressure is consistent with research conducted by (Allison & Reger, 1998; Gabrielsen, Warberg et al., 2000; Nishimura & Onodera, 2000). In this study they also studied recovery of heart rate in cold, mild and warm water. They found that recovery of heart rate was more in mild water as compared to the warm water.

Studies on the Effects of Hot Immersion on Heart Rate

Tabara et al., (2004) hypothesized that imbalance of ANS due to hot water immersion can lead to disturbance in the hemodynamic process and alteration in the cardiovascular parameters. They studied age dependent effect of hot water immersion on heart rate and blood pressure. They found that systolic blood pressure was significantly altered in elder subjects, however this change was not significant in young subjects. Both high frequency (HF) (0.2 Hz)and low frequency (LF) (0.1 Hz) heart rate were significantly increased in elderly and young subjects.  

Autonomic nervous system (ANS) is the essential component of the thermoregulation homeostatic mechanism in the body. This ANS controls heart rate and blood pressure. Heart rate measurement has been emerged as the important method for the assessment of the ANS because it is safe, noninvasive, and relatively inexpensive. It has been shown that immersion in warm water produces effect on the ANS by decreasing the sympathetic activation and by increasing the vagal tone (Miwa et al., 1997; Nishimura & Onodera, 2000, 2001; Perini & Veicsteinas, 2003). Non pharmacological techniques like hot water immersion are useful in studying ANS which has wide applicability in in a range of physiological mechanism. In previous studies it has been well established that water immersion has effect on heart rate variability and it is related to alteration in the ANS in reducing sympathetic nervous system (SNS) activity and increasing parasympathetic nervous system (PNS) activity (Mourot et al., 2008; Mourot et al., 2007; Nagasawa et al., 2001; Nishimura & Onodera, 2000, Nishimura & Onodera, 2001). Thus, ANS has effects on the peripheral circulation, blood pressure and central nervous system.     

Blood flow increases with increase in temperature. It is believed that increased blood flow is due to the increased muscle flow because this warm water immersion is used as muscle relaxation therapy. This muscle blood flow is both under auto regulation and neurogenic regulation (Shankar and Randall, 2002). Hemodynamic and ANS changes in warm water immersion were studied in both elderly patients with heart disease and in normal people because these changes may lead to sudden death during bathing in elderly people. During immersion in the hot water, elderly patients can’t maintain homeostasis because their ANS is not capable to respond dynamically to heat stress of hot water.

In our experiment, we selected 37°C temperature because temperature around 40°C may not be tolerable by the subjects. Time of immersion also should be always more than 10 minutes because heart rate measurement generally requires steady state cycle for at least 5 minutes. In our experiment we followed the trend by keeping minimum immersion time of 10 minutes.

Experimental Setup and Results

One of the major limitations of the study was that less number of participants was involved in this study. To get more robust data, experiment with more number of participants required. In this young male were selected. In the next experiment, subjects with different age group and gender should be selected. It would be helpful to evaluate effect of hot water immersion on child, young people and adults. Also, it would be helpful to evaluate comparative effect of hot water immersion on male and female.

References:

Allison, T.G., & Reger, W.E. (1998). Comparison of responses of men to immersion in circulating water at 40.0 and 41.5 degrees C. Aviation, Space, and Environmental Medicine, 69(9), 845–850.

Gabrielsen, A., Warberg, J., Christensen, N.J., Bie, P., Stadeager, C., Pump, B., et al. (2000). Arterial pulse pressure and vasopressin release during graded water immersion in humans. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 278(6), R1583–R1588.

Kamath, M.V., Watanabe, M. (2016). Heart Rate Variability (HRV) Signal Analysis: Clinical Applications. CRC Press. Taylor & Francis Group.

Miwa, C., Sugiyama, Y., Mano, T., Iwase, S., & Matsukawa, T. (1997). Sympatho-vagal responses in humans to thermoneutral head-out water immersion. Aviation, Space, and Environmental Medicine, 68(12), 1109–1114.

Mourot, L., Bouhaddi, M., Gandelin, E., Cappelle, S., Dumoulin, G., Wolf, J.P., et al. (2008). Cardiovascular autonomic control during short-term thermoneutral and cool head-out immersion. Aviation, Space, and Environmental Medicine, 79(1), 14–20.

Mourot, L., Bouhaddi, M., Gandelin, E., Cappelle, S., Nguyen, N.U., Wolf, J.P., et al. (2007). Conditions of autonomic reciprocal interplay versus autonomic co-activation: Effects on non-linear heart rate dynamics. Autonomic Neuroscience, 137(1), 27–36.

Nagasawa, Y., Komori, S., Sato, M., Tsuboi, Y., Umetani, K., Watanabe, Y., et al. (2001). Effects of hot bath immersion on autonomic activity and hemodynamics: Comparison of the elderly patient and the healthy young. Japanese Circulation Journal, 65(7), 587–592.

Nishimura, M., & Onodera, S. (2000). Effects of supine floating on heart rate, blood pressure

and cardiac autonomic nervous system activity. Journal of Gravitational Physiology, 7(2), 171–172.

Nishimura, M., & Onodera, S. (2001). Effects of water temperature on cardiac autonomic nervous system modulation during supine floating. Journal of Gravitational Physiology, 8(1), 65–66.

Perini, R., & Veicsteinas, A. (2003). Heart rate variability and autonomic activity at rest and during exercise in various physiological conditions. European Journal of Applied Physiology, 90(3-4), 317–325.

Shankar, K., & Randall, K. (2002). Therapeutic Physical Modalities. Hanley and Belfus, Philadelphia.

Tabara, Y., Kohara, K., Okuda, Y., Kondo, I., Suyama, K., & Miki, T. (2004). Effects of hot water immersion on autonomic activity and hemodaynamics. American Journal of Hypertension, 17 (S1), 234A.

Taheri, A., Habibi, A., Ghanbarzadeh, M., & Ramezani, P. (2012). Changes in blood pressure, heart rate and perception of fatigue in Recovery to primary active state in water with three different temperatures, after an exhausting activity. International Research Journal of Applied and Basic Sciences, 3(7), 1485-1489.

Vrijkotte TG, van Doornen L J, & de Geus EJ. (2000). Effects of work stress on ambulatory blood pressure, heart rate, and heart rate variability. Hypertension, 35(4), 880-6.