Sports health quantification method and system implementation based on multiple thermal physiology simulation

We randomly divided 18 male college students (without training experience) who volunteered to participate in the experiment into two groups. The control group (NE) group was a standard room temperature exercise group (n=9, 26±1°C), and the high fever group (HE) group was a thermal environment exercise group (n=9.38±1°C). The relative humidity (%RH) is 73%±3%. The subjects had no history of disease on physical examination and we ensured that all subjects had rest time and regular diet 5 days before the experiment [2]. They do not consume coffee, alcohol, and other stimulants, and they wear suitable clothing to participate in the test. The basic situation is shown in Table 1.

We use POWER MAXV II power car and POLARS 810 equipment to measure heart rate. The subjective physical performance rating (RPE) was assessed using the BorgRPE scale. Before exercise and immediately after training, we take 20μl of micro finger blood, use the micro whole blood diacetyl mono oxime method (we add the blood to a test tube containing 0.5 ml of 1% sodium fluoride, immediately add 1.5 ml of 10% trichloroacetic acid, shake well, 3000 rpm/min centrifugation for 10 min), 721 spectrophotometers to measure the blood urea (BUN) level. Standard Rectal Thermistor measures the rectal temperature (Tre), and the miniature probe is placed 6–8 cm in the rectum.

The two groups of subjects were pedalling for 60 min at room temperature and the thermal environment with 55% VO₂max. HR, RPE and Tre were recorded before exercise, every 15 min during practice and immediately after exercise; and BUN concentration and fatigue index (FI) was measured immediately after exercise. The experiment was conducted in the exercise physiology laboratory in July 2019.

The experimental data is represented by the mean and standard deviation (X±SD). We use the SPSS11.5 statistical software to use repeated measures one-way analysis of variance (ANOVA) to process the data statistically. The Pearson correlation coefficient represents the correlation between HR and RPE. The level of academic significance difference was set to 0.05.

The heart rates of the two groups of subjects before exercise were 73.6±5.6 times and 75.1±5.7 times, respectively (P>0.05). They exercised in room temperature and thermal environment and showed a gradually increasing trend every 15 min. The heart rate rose fastest at 15 min before exercise, the heart rate at the end of 15 min in the NE group was 110.7±8.5, the HE group was 113.3±7.8, and the HE group was slightly higher, but there was no significant difference (P>0.05). At 30 min, 45 min and 60 min of exercise, the heart rate of the HE group was significantly higher than that of the NE group (P<0.01). Immediately after training, the heart rates of the two groups were 143.8±8.8 and 155.9±9.1, reaching their respective highest heart rates during exercise.

The RPE levels of the two groups of subjects before exercise were very relaxed, and the RPE values were 8.1±0.2 and 8.0±0.2, respectively (P>0.05). With the prolongation of exercise time, the HR and RPE values showed an increasing trend. At the end of the exercise for 15 min, the RPE of the NE group and HE group was significantly higher than before training (P0.05). NE group felt more relaxed than the HE group immediately after exercise (RPE were 15.2±0.4, 16.1±0.5, P<0.01). The RPE of the NE group was significantly lower than that of the HE group at the three-time points of 30 min, 45 min and 60 min (P<0.01). Rehydration was performed at the end of the exercise. After 2 h of rest, the RPE of NE and HE groups were 8.4±0.4 and 8.9±0.4, respectively. See Figure 1 (1A represents the correlation between the HR of the two groups and exercise time, and 1B illustrates the correlation between the RPE of the two groups and exercise time). From 15 min of movement to the end of training in the HE group, the correlation coefficient between HR and RPE was 0.839 (P<0.05), as shown in Figure 2.

Fig. 1

Fig. 2

Comparison between groups: There was no significant difference in the Tre of the two groups before exercise (P=0.12). After 15 min of training, the Tre of the NE group and the HE group were 36.97±0.09°C and 36.91±0.06°C, respectively (P=0.069); after 30 min of exercise, they were, respectively, 37.46±0.07°C and 37.71±0.05°C (P<0.01). Intra-group comparison: At the end of training for 15 min, 30 min, 45 min and 60 min, the Tre of the NE group and the HE group were significantly higher every 15 min than the previous 15 min, but the increase in the two groups was different: the rise in Tre slowed down in the NE group after 30 min of exercise; however, in the HE group, it continued to increase. In general, with the extension of exercise time, the Tre of the two groups improved significantly, but the difference between the groups is indeed more and more significant. See Figure 3.

Fig. 3

After 60 min of exercise, the NE group and the HE group lost 0.72±0.07 kg and 0.93±0.07 kg. There was a significant difference between the two groups (P<0.01). The total sweat volume of the NE group and the HE group were 0.864±0.081 L and 1.059±0.083 L, respectively. The total sweat rate of the NE group and the HE group were 56.1%±3.1% and 65.7%±2.8%, respectively. The total sweat volume of the NE group The real sweating rate was significantly lower than that of the HE group (P<0.01).

There was no significant difference in BUN between the two groups before exercise (P=0.357). The BUN of the NE group was significantly lower than that of the HE group immediately after exercise (3.63±0.11 mmol/L and 4.63±0.32 mmol/L, P<0.01). The two groups’ FI was 78.6%±8% and 86.4%±7%, which were also significantly different (P<0.01).

Participants at room temperature and thermal environment at 55% VO₂max exercise, HR and RPE all gradually increased with the extension of exercise time, but the changes in each period were different [9]. Although the increase in the first 15 min was the largest, there was no significant difference in HR at the end of 15 min between the NE group and the HE group (P=0.138). It increased significantly after 30 min of exercise. Controlling the exercise time within 30 min can more effectively avoid adverse effects; if it is to adapt to the training and competition in the thermal environment, the single exercise time is better than 30 min, so the stimulation caused by this is more profound, and the heat is easier to form.

However, the specific exercise intensity and time of thermal acclimatisation are still controversial. Some scholars believe that increasing VO₂max by about 15% is the standard for thermal acclimatisation. Some scholars have proposed that intermittent or continuous training with an intensity of 50% VO₂max can improve the body's heat resistance. Some scholars have found that training with 59% VO₂max submaximal intensity for 10–12 days can make the body adapt to the thermal environment.

The RPE indicator is a quantitative indicator of the stimulation of muscles, respiration, cardiovascular etc. that are transmitted to the brain during exercise. The brain responds to its working ability. Physiologists generally believe that the RPE index can reflect the body's functional state to a certain extent. When the RPE value (level) increases significantly, it indicates a decline in the body's function. The results of this experiment showed that at the end of 15 min, the RPE value of the HE group was significantly higher than that of the NE group (P<0.05), but the corresponding HR during the same period did not change significantly (P>0.05). RPE in the NE group continued to increase during 15–30 min of exercise, but the increase was slow. The RPE value of the HE group increased significantly during the same period, and the difference between the groups was very significant (P<0.01), but the corresponding HR during the same period was not significantly different. The increase in value may be related to the psychological impact of the thermal environment [10]. The RPE value of exercisers in the thermal environment (40°C) is significantly higher than that of exercisers at room temperature (23°C). It is believed that exercise in a thermal environment significantly increases psychological stress. The study results suggest that for a short period of moderate-intensity movement in a high-heat environment, the influence of temperature may play a significant role.

When the Swedish physiologist Borg developed the RPE scale, he did not count the correlation between RPE and HR in a thermal environment. From the results of this experiment, we observe that the correlation coefficients of RPE and HR are highly correlated (r=0.839, P<0.05) when exercising in a thermal environment. It should be noted that the subjects in this experiment are college students with no training experience, and their adaptability to multiple thermophysiological simulations is not as good as that of professional athletes, so that the results may reflect the correlation between RPE and HR in a high-heat environment more objectively.

The energy consumption of exercise in a hot environment is about 20 times higher than that in a calm state, of which no more than 25% is used for muscle work, and the excess heat energy must be discharged. Heat energy is transferred from the muscles to the blood and gradually reaches the deep part of the body. The temperature of the deep part is not easily changed, so it can better reflect the degree of heat accumulation in the body. It can be seen from the experimental results that in the early stage of the exercise, exercise causes changes in the perception of the hypothalamic thermal regulation centre, triggers blood circulation regulation and blood redistribution between internal organs and muscles, and causes the deep temperature to rise moderately. At this time, the environmental temperature has an impact on the deep climate, although this is not big. After 30 min of continuous exercise, Tre increased sharply in the HE group (P<0.01). After 45 min of training, the increase of Tre in the NE group slowed down. Ordinary people exercise for 60 min at a sub-maximal intensity under average humidity and temperature environment. After 35 min or 45 min of exercise, the deep temperature has a plateau, and the deep temperature shows a steady state. This reflects the human body's good adjustment ability when exercising in a typical environment; the continuous increase in Tre in the HE group is consistent with the results of Marino et al. The analysis is mainly due to excessive heat accumulation in the body due to exercise in a thermal environment, and delayed heat dissipation. The ability of autonomous body temperature regulation is unbalanced [11]. At this time, the body temperature exceeds the average temperature of the cells, and if the time is too long, the cells will be damaged. If the body temperature is >42°C, it will cause substantial damage to the cells. Athletes can bear the temperature of 39–41°C in the deep part for a long time. Still, the safety range of their body temperature that can be adjusted in strenuous exercise is limited, and the thermal limit is 42°C. When Tre reaches 40–41°C, central nervous system dysfunction will occur, accompanied by symptoms such as nausea, dizziness, reduced sweating rate and confusion; if Tre reaches 43–44°C, it is easily capable of causing cell damage, brain damage and even death. Therefore, it is imperative to control and maintain the deep temperature within a safe range when exercising in a hot environment.

As a result of exercise in a hot environment, the loss of K+, Na+ and Mg+ is considerable, and the body sweats perceptibly. It is prone to dehydration. The body temperature increases significantly; muscle cramps, heat exhaustion and other symptoms can also be observed. In this experiment, the weight of the HE group decreased significantly after exercise, and the total sweating volume and total sweating rate of the HE group were also significantly higher than those of the NE group (P<0.01). After exercise, four subjects in the HE group had small calf gastrocnemius muscles. Comprehensive analysis believes that dehydration and electrolyte loss are the main threats when exercising for a long time in a hot environment. Dehydration causes a decrease in plasma volume and a decrease in circulating blood volume, resulting in decreased return blood volume and reduced stroke output [12]. At this time, it can only rely on increasing the heart rate to compensate for the insufficient circulating blood volume, which increases the burden on the heart and reduces work efficiency. Excessive sweating (dehydration) of the body is one reason for the increase in HR and Tre. The experimental results also confirmed that weight loss, excessive sweating and increased sweating rate are related. This situation also reflects the compensatory effect of the increased heart rate in the HE group and the adverse effect of the continuous increase in Tre. Therefore, it is imperative to avoid dehydration and reduce the loss of electrolytes in the body when exercising in a hot environment.

After exercise, the BUN and FI values of the HE group were significantly higher than those of the NE group (P<0.01), reflecting a greater degree of HE fatigue. Our analysis is an exercise in a thermal environment. The heat inside the body is mainly moved to the skin through blood circulation. A large amount of blood supply in the body maintains heat dissipation. Excessive sweating increases the burden on the heart and reduces the output power. Also, the influence of the thermal environment on the psychological aspect cannot be ignored. The combined effect of physiological and psychological factors leads to the increase of FI in the HE group. The subjects still need to complete a fixed-intensity exercise when the heart output rate is reduced and only increases the muscle output power. Still, the plasma volume caused by dehydration is reduced, the blood is thick and the circulating blood volume is reduced [13]. A series of changes tales place, so that the elimination of ammonia, the blood supply of tissues and organs (mainly the liver) etc. are affected, and this may cause a significant increase in BUN. Besides, the exercise time is longer, and amino acids and branched-chain amino acids participate in the energy supply. Since more ammonia enters the blood, the accumulation of plasma NH⁴⁺ may also increase the BUN level [14]. Still, the contribution of this pathway to BUN is not the main one – because, during exercise, branched-chain amino acids account for only a tiny part of the energy supply [15].