ABSTRACT
To explore the effects of different fluid replenishment methods on the internal environment, body thermal regulatory response and severe heatstroke of 5-km armed cross-country training soldiers. Methods A Special Force officers and soldiers who participated in 5-km armed cross-country training (2-3 times a week, 25-30 minutes each time for 3 weeks) during summer training from June to July in 2018 were enrolled, and they were divided into three groups according to the random number table, with 300 trainees in each group. 200 mL of drinking fluids were given to each group 15 minutes before and after each 5-km armed cross-country training: A group with boiled water, B group with purified water, and C group with beverage prepared by pharmaceutical laboratory of the 990th Hospital of PLA Joint Logistics Support Force (100 mL containing 6 g carbohydrates, 42 mg sodium, and 11 mg potassium). The venous blood was collected before and after the last training or during the onset of severe heatstroke to do the following tests: serum cardiac troponin I (cTnI, chemiluminescence), MB isoenzyme of creatine kinase (CK-MB, immunosuppressive), serum creatinine (SCr, enzymatic method), urea nitrogen (BUN, enzymatic method), alanine aminotransferase (ALT, tryptase), aspartate transaminase (AST, tryptase), and Na+, K+, Cl- (electrode method). The heart rate (HR) and core temperature (Tc, anal temperature) were monitored at the same time. The amount of sweat in training and the occurrence of severe heatstroke were also recorded. Results There was no significant difference in heart, liver, kidney function, electrolyte and body heat regulation reaction among three groups of 5-km armed cross-country trainees before training. Compared with before training, the levels of serum cTnI, CK-MB, SCr, BUN, ALT, AST, HR and Tc were significantly increased after training or during the onset of severe heatstroke in three groups, while the contents of Na+, K+, Cl- were significantly decreased, but the increase or decrease of group C was relatively smaller compared with group A and group B [cTnI (μg/L): 0.9 (0.6, 1.4) vs. 1.1 (0.7, 2.8), 1.0 (0.6, 3.3); CK-MB (U/L): 7.0 (5.0, 11.0) vs. 9.0 (6.0, 14.5), 8.0 (6.0, 15.0); SCr (μmol/L): 92.09±18.64 vs. 102.78±18.77, 103.64±20.07; BUN (mmol/L): 7 (6, 9) vs. 9 (8, 11), 10 (8, 13); ALT (U/L): 27 (22, 34) vs. 36 (30, 43), 34 (27, 43); AST (U/L): 37 (31, 48) vs. 41 (34, 50), 39 (34, 51); HR (bpm):87.01±17.07 vs. 95.88±21.06, 96.59±22.04; Tc (℃): 37.73±0.81 vs. 38.03±1.05, 38.10±1.04; Na+ (mmol/L):150.14±3.86 vs. 144.18±8.89, 144.04±9.39; K+ (mmol/L): 4.32±0.57 vs. 4.15±0.62, 4.13±0.51; Cl- (mmol/L):100.43±3.71 vs. 98.42±4.24, 98.41±4.58; all P < 0.01]. The incidence of severe heatstroke in group C was significantly lower than that in group A and group B [1.67% (5/300) vs. 5.00% (15/300), 5.33% (16/300), χ2 = 6.424, P = 0.040]. There was no significant difference in sweating volume in groups A, B, C (g: 370.47±48.71, 370.85±50.66, 370.17±50.21, F = 0.014, P = 0.986). There was no significant difference in the above indexes between group A and group B (all P > 0.05). Bi-classification Logistic regression analysis showed that the increase of HR, Tc and excessive loss of Na+, K+, Cl- were risk factors for severe heatstroke [odds ratio (OR) was 0.848, 0.138, 1.565, 17.996 and 2.328 respectively, all P < 0.01]. Conclusions Timely supplementation of carbohydrate, sodium and potassium ions can effectively change the internal environment and body heat regulation reaction of 5-km armed cross-country trainees, so as to reduce the occurrence of severe heatstroke. The increases of HR, Tc and excessive loss of Na+, K+, Cl- are risk factors for severe heatstroke.
ABSTRACT
Objective To explore the relationship between training burnout, sleep quality and heat regulation response, severe heatstroke in people performed 5-km armed cross-country training. Methods 600 male officers and soldiers who participated in 5-km armed cross-country training in summer from 2017 to 2018 were enrolled. All trainees participated in 5-km armed cross-country training in environment with ambient temperature > 32 ℃ and (or) humidity > 65%. They were divided into two groups according to whether severe heatstroke occurred during 5-km armed cross-country training. The age, military age, body mass index (BMI), physical fitness score, external environment (such as ambient temperature, relative humidity, wind speed, heat index), training burnout score and Pittsburgh sleep quality index scale (PSQI) score, heart rate (HR), core temperature (Tc), sweating volume and serum Na+, K+, Cl- levels were compared between the groups. The risk factors of severe heatstroke during 5-km armed cross-country training were screened by binary multivariate Logistic regression analysis. Results There were 26 cases of severe heatstroke in 600 trainees who participated in 5-km armed cross-country training, with an incidence of 4.33%. There was no significant difference in age, military age, BMI, physical fitness score and external environment of 5-km armed cross-country training between people with or without severe heatstroke. Compared with those without severe heatstroke, the dimensions of training burnout and the total average scores of training burnout of severe heatstroke personnel before 5-km armed cross-country training were increased significantly (physical and mental exhaustion score: 12.4±2.5 vs. 9.4±3.5, training alienation score: 8.8±2.8 vs. 5.8±2.3, low sense of achievement score: 8.2±2.7 vs. 5.6±2.3, total score of training burnout: 9.8±3.2 vs. 6.9±3.2, all P < 0.01), all factors except daytime dysfunction (DD) of PSQI and total PSQI score were also increased significantly [sleep quality (SQ) score: 1.0 (1.0, 2.0) vs. 1.0 (1.0, 1.0), fall asleep time (SL) score: 2.0 (1.0, 3.0) vs. 1.0 (1.0, 1.0), sleep time (SH) score: 1.0 (0.8, 2.0) vs. 1.0 (0, 1.0), sleep efficiency (SE) score: 1.0 (0, 1.0) vs. 0 (0, 0.8), sleep disorder (SD) score: 2.0 (1.0, 3.0) vs. 1.0 (0, 2.0), total PSQI score: 1.0 (1.0, 2.0) vs. 1.0 (0, 1.0), all P < 0.01], HR was increased significantly at onset (bpm: 120.00±10.57 vs. 86.49±14.91, P < 0.01), Tc was increased significantly (℃: 41.46±0.57 vs. 37.97±0.83, P < 0.01), serum electrolyte contents were decreased significantly [Na+ (mmol/L): 130.54±5.97 vs. 143.15±10.56, K+ (mmol/L): 3.72±0.44 vs. 4.37±0.50, Cl- (mmol/L):97.58±4.80 vs. 102.10±2.39, all P < 0.01], and the amount of sweat during training was increased significantly (g: 395.81±16.16 vs. 371.88±40.76, P < 0.01). Binary multivariate Logistic regression analysis showed that total score of training burnout [odd ratio (OR) = 0.653, 95% confidence interval (95%CI) = 0.563-0.757], total PSQI score (OR =0.693, 95%CI = 0.525-0.916), HR (OR = 0.871, 95%CI = 0.838-0.908), Tc (OR = 0.088, 95%CI = 0.043-0.179), sweating volume (OR = 0.988, 95%CI = 0.979-0.997), Na+ (OR = 1.112, 95%CI = 1.069-1.158), K+ (OR = 13.900, 95%CI = 5.343-36.166), Cl- (OR = 1.393, 95%CI = 1.252-1.550) were independent risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). Conclusion Increase in training burnout, total PSQI score, excessive changes of body heat regulation response and excessive loss of Na+, K+, Cl- in serum are independent risk factors for severe heatstroke during 5-km armed cross-country training under the same conditions with high temperature and humidity environment.
ABSTRACT
Objective@#To explore the relationship between physiological parameters changes and severe heatstroke induced by 5-km armed cross-country training.@*Methods@#A total of 521 male officers and soldiers from a special team who participated in the summer training of 5-km armed cross-country training from year 2016 to 2017 were enrolled. All trainees participated in 5-km armed cross-country training in high temperature and humidity environment of ambient temperature > 32 ℃and (or) relative humidity > 65%. The trainees were divided into two groups according to the incidence of severe heatstroke in the course of training. The age, enlistment time, constitution score, body mass index (BMI), external environment (ambient temperature, relative humidity, wind speed, heat index) of trainees of the two groups, and the change rates of arterial blood oxygen saturation (SaO2), body temperature, pulse and blood pressure within 5 minutes after the 5-km armed cross-country training were compared between the two groups. The risk factors of severe heatstroke were screened by two classified Logistic regression analysis, and the predictive value of various risk factors of severe heatstroke was analyzed by the receiver operator characteristic curve (ROC).@*Results@#In 521 trainees of 5-km armed cross-country training, 29 trainees suffered from severe heatstroke accounting for 5.57%. There was no significant difference in the age, enlistment time, constitution score, BMI, or external environment during 5-km armed cross-country training between severe heatstroke group and non-severe heatstroke group. Compared with those without severe heatstroke, the descending rates of body temperature, pulse, blood pressure and SaO2 increased rate within 5 minutes after 5-km armed cross-country training of severe heatstroke trainees were significantly decreased [temperature descending rate: (0.67±0.30)% vs. (1.43±1.28)%, pulse descending rate: (7.53±5.21)% vs. (13.48±8.07)%, blood pressure descending rate: (9.28±6.84)% vs. (19.42±7.73)%, SaO2 increased rate: (0.51±0.39)% vs. (1.50±1.43)%, all P < 0.01]. Two classification Logistic regression analysis showed that the temperature descending rate [odds ratio (OR) = 0.485, 95% confidence interval (95%CI) = 0.289-0.817], pulse descending rate (OR = 0.903, 95%CI = 0.845-0.965), blood pressure descending rate (OR = 0.841, 95%CI = 0.790-0.896), and SaO2 increased rate (OR = 0.421, 95%CI = 0.250-0.711) were the risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). ROC curve analysis showed that temperature descending rate [area under ROC curve (AUC) = 0.659, 95%CI = 0.604-0.714], pulse descending rate (AUC = 0.730, 95%CI = 0.762-0.900), blood pressure descending rate (AUC = 0.831, 95%CI = 0.659-0.801), SaO2 increased rate (AUC = 0.711, 95%CI = 0.655-0.767) could be used for the incidence of severe heatstroke prediction during 5-km armed cross-country training (all P < 0.01), and the predicted value was the same.@*Conclusions@#Under the same conditions, the severe heatstroke during 5-km cross-country training is closely related to the descending rates of body temperature, pulse, and blood pressure as well as SaO2 increased rate within 5 minutes after the training, whose predictive values for severe heatstroke were the same.