ECSS Paris 2023: CP-AP06
INTRODUCTION: For athletes, maintaining daily training can be essential. Physical stress disrupts normal physiological balance or homeostasis, including the immune system, especially during high-intensity exercise. Natural killer (NK) cells, a type of immune cell, are sensitive to exercise, and a decrease in NK cell activity contributes to immune system dysfunction. Therefore, maintaining high NK cell activity after exercise is a key factor in improving long-term performance. Recently, it has been reported that maintaining deep muscle temperature with a heat-retaining function after exercise can improve performance. The aim of this study was to investigate the acute effects of wearing thermoretentive tights after high-intensity exercise on immune function. METHODS: Thirteen healthy adult males (21-29 years of age) participated in a randomized crossover study comparing conditions with and without heat-retaining tights (prototype of Thermal Charge®, Mizuno, Japan). The exercise protocol consisted of resistance training followed by high-intensity interval training (HIIT) on a bicycle ergometer. The effects on NK cell activity and heat shock protein 60 (HSP60) were assessed at baseline, 0, 30, and 150 minutes after exercise. A two-way ANOVA was performed, and when significant interactions were observed, trend analysis was performed for each group. A significance level of p < 0.05 was used. RESULTS: All 13 participants completed the exercise. The control group showed a significant decrease in blood NK cell activity from baseline to 150 minutes after high-intensity exercise. In contrast, there was no decrease in NK cell activity from baseline to 150 minutes post-exercise when wearing thermoretentive tights. In addition, a significant increase in blood heat shock protein 60 concentration was observed only when wearing thermal-keeping tights. CONCLUSION: Wearing thermal-keeping tights prevented the decline in serum NK cell activity at 150 minutes after high-intensity exercise and increased serum HSP60 levels after exercise. The thermoretentive garments used in this study have been shown to maintain both deep and superficial muscle temperature during exercise. Thus, it is suggested that heat retention in deep muscles may have contributed to the suppression of immune decline.
Read CV Keisuke TokunagaECSS Paris 2023: CP-AP06
INTRODUCTION: The changes in deoxyhemoglobin ([HHb]) derived from near-infrared spectroscopy (NIRS) are commonly calibrated with an arterial occlusion (AO) to examine muscle oxygenation and microvascular responsiveness. However, exercise alters hemodynamic and metabolic responses, which could affect this calibration method. This study aimed to examine the influence of exercise on AO variables. METHODS: Thirty-six endurance-trained males (28 ± 9 years, 75,9 ± 9,4 kg, 1,78 ± 0,08 m) completed a cardiopulmonary exercise testing (CPET) and a 5-km time-trial (TT) on an ergocycle. The NIRS device (PortaMon, Artinis Medical Systems BV, The Netherlands) was installed on the distal part of the right vastus lateralis muscle to record changes in muscle oxygen parameters during AO executed before and after each test. The resting baseline (30 sec), the AO amplitude (difference between the hyperemia spike and baseline) and the reperfusion slope of tissue oxygen saturation (% StO2, 10 sec post hyperemia spike) were evaluated. Student t tests were used to compare baseline, amplitude and reperfusion slope of [HHb] and TSI signals. RESULTS: [HHb]baseline and [HHb]slope were similar pre- and post-CPET and between tests (CPET vs TT). [HHb]amplitude was higher post- vs pre-CPET (p<0.001) and post-TT vs post-CPET (p<0.001). Both CPET and TT increased TSIbaseline (p=0.005) and decreased TSIamplitude (p=0.019) and TSIslope (p<0.001). TT also decreased TSIslope (p<0.001). Finally, TSIbaseline was different between CPET and TT (p=0.023), but TSIamplitude and TSIslope were similar. CONCLUSION: These results suggest that CPET and TT independently impacted maximal deoxygenation, highlighting the importance of performing an AO after every type of exercise to accurately calibrate [HHb]. Futhermore, exercise altered microvascular responsiveness, but with similar effect for CPET and TT.
Read CV Pénélope Paradis-DeschênesECSS Paris 2023: CP-AP06
INTRODUCTION: Chemical Corps personnel wear nuclear, biological, and chemical (NBC) protective clothing along with 20 kg of equipment during operations, imposing significant physiological stress. NBC protective clothing restricts sweat evaporation and heat dissipation, increasing heat stress and metabolic burden (1). Heart rate is a widely used physiological indicator for workload prediction, while body composition factors such as body fat percentage (PBF) and body mass index (BMI) influence metabolic response (2,3). However, the extent to which these factors contribute to energy metabolism estimation remains unclear. This study aims to develop an optimized model for predicting metabolic equivalents (METs) based on physiological parameters. METHODS: Twenty-five male military personnel (age: 25.32 ± 2.26 years; height: 170.42 ± 4.88 cm; weight: 64.9 ± 11.28 kg) participated. They performed treadmill walking/running at different loads (0 kg, 10 kg, and 20 kg) and speeds (4 km/h, 6 km/h, and 8 km/h) while wearing NBC protective clothing under controlled conditions (temperature: 25°C, humidity: 70%). METs were measured using a portable metabolic analyzer, and body composition was assessed prior to testing. Simple and multiple linear regression analyses were performed to determine the optimal METs prediction model. RESULTS: Multiple regression analysis showed that the combination of HRRratio and PBF had the highest coefficient of determination (R² = 0.867, p < 0.001) for METs, with the model: METs = 4.116 + 0.939 × HRRratio − 0.051 × PBF. If PBF was unavailable, HRRratio and BMI provided a second-best model (R² = 0.862, p < 0.001): METs = 5.179 + 9.370 × HRRratio − 0.088 × BMI. When no body composition data was available, HRRratio alone remained a strong predictor (R² = 0.852, p < 0.001): METs = 3.243 + 9.322 × HRRratio. CONCLUSION: This study developed a predictive model for energy metabolism in personnel wearing NBC protective clothing, confirming HRRratio as a reliable predictor of METs, with or without body composition parameters. The findings align with prior research on heart rate-based energy estimation and the physiological strain of protective gear (4,5). NBC protective clothing has been shown to increase core temperature by up to 11.2°C during moderate to heavy workloads, significantly elevating energy demands (1). Environmental conditions further exacerbate metabolic burden, emphasizing the need for context-specific models (6). While this model provides accurate estimations under controlled conditions, further validation in extreme environments is necessary. Future research should explore additional physiological markers to refine the model for broader operational use. Reference: 1. McLellan, et al., Aviat Space Environ Med., 1996 2. Swain, et al., Med Sci Sports Exerc., 1997 3. Brage, et al., Eur J Appl Physiol., 2006 4. Havenith, et al., Energy Build., 2002 5. Taylor, et al., Ind Health., 2006 6. McLellan, et al., Ind Health., 2006
Read CV YiXin LinECSS Paris 2023: CP-AP06