ECSS Paris 2023: CP-MH20
INTRODUCTION: Adequate hydration and water availability are regarded as essential for maintaining both physical and cognitive performance, particularly in the heat. More recent studies suggest that ad libitum drinking is sufficient to maintain performance so that additional drinking may not be required to improve performance for a range of situations. Maintaining posture is a critical and complex ability with few studies showing that prolonged exercise without fluid ingestion negatively affects postural stability. However, it is not known whether fluid replacement overlaid by heat stress has a similar affect. This study investigated whether the availability of water ad libitum during exercise heat stress alters postural sway. METHODS: Nine healthy volunteers (6 men, 3 women) completed a 60 min simulated military march in warm conditions (30 °C, 50% rh) dressed in military fatigues, helmet and carrying a pack (10% body mass). Participants completed two trials in randomised reverse order with either ad libitum fluid availability (HYD) or fluid restricted (NHYD). The march consisted of 3 x 20 min stages escalating each 10 min in speed and gradient (range 4 – 7 km/h; 1% -5.5% gradient) with each stage separated by ~ 5 min when measures of postural sway, lactate, and other measures of fatigue were completed. During the march, heart rate (HR), core and skin temperatures (Tc, Ts, respectively) were recorded continuously with perceptual measures of rating of perceived exertion (RPE) and thermal sensation (ThS) recorded each 5 min. Nude body mass pre and post march were recorded adjusted for consumed water to calculate sweat rate. RESULTS: During the march Tc increased (P < 0.05) from 15 min in both conditions and was similar by the end (38.3 ± 0.6 NHYD vs 38.5 ± 0.5 °C HYD). Ts increased (P < 0.05) over time in both conditions and was 32.7 ± 1.0 °C for NHYD and 32. ± 1.1 °C for HYD (P > 0.05). HR increased during the march but was not different between conditions reaching 166 ± 9.9 bpm (HYD) and 156 ± 26.8 bpm (NHYD) by the end. The amount of water consumed during HYD was 495.1 ± 190.3 ml. The sweat rate was 1.65 ± 0.36 l/hr for HYD and higher than 1.23 ± 0.23 l/hr (P <0.05) for NHYD. Postural sway measured as the centre of pressure (COP) path at pre, 20, 40 min and post-exercise was not different between conditions ranging from 0.21 – 0.22m (NHYD) and 0.21 – 0.24m (HYD). CONCLUSION: Heat strain during the simulated march with the addition of water availability did not result in thermoregulatory or cardiovascular differences between conditions. These findings are not dissimilar to studies showing that drinking to dictates of thirst is enough to maintain performance. However, postural sway as measured by COP was not different with and without the availability of water which suggests that this critical human motor control ability remains intact following a long march. The reasons for this are not clear but might include a different exercise modality.
Read CV Frank MarinoECSS Paris 2023: CP-MH20
INTRODUCTION: It is well known that basic military training (BMT) is physically and mentally demanding for the conscripts [1]. The current study aims to examine how conscripts in the Swiss Armed Forces physically prepare to BMT, what resources they utilize or what training methods are being used, if they feel “military ready” at the beginning of BMT and if a physical preparation for BMT results in less injuries during BMT. METHODS: At the beginning of the BMT 532 male conscripts (20 ± 1 years, 178 ± 7 cm, 73.8 ± 11.1 kg) of communications intelligence, armored infantry, rescue technicians and fusilier infantry performed objective physical fitness tests (PFT) [1] and answered questionnaires to assess physical activity behavior and the use of supported training methods prior to the start of BMT. Additionally, musculoskeletal injuries suffered during the BMT was provided by medical records. Binomial logistic regressions were performed to predict the presence of an overuse or an acute injury based on points reached in the PFT, subjective readiness, MET-minutes of moderate physical activity before BMT (‘MET moderate’), and MET-minutes of vigorous physical activity before BMT (‘MET vigorous’). RESULTS: A 19% of the Swiss conscripts changed their physical activity training behavior due to the upcoming BMT and 10% of conscripts utilized a smartphone application as a training aid. A total of 194 (36.5%) conscripts were injured, 70 acute and 143 overuse injuries during BMT were reported. The Spearmans rank correlation between PFT and subjective readiness was r = 0.37, between subjective readiness and ‘MET moderate’ r = 0.19, and between subjective readiness and ‘MET vigorous’ r = 0.41. The binomial logistic model revealed the PFT as a significant predictor for overuse injury (β = -0.023, SE = 0.011, z = -2.213, p = 0.027, OR = 0.977). However, subjective readiness (p = 0.89), ‘MET moderate’ (p = 0.37), and ‘MET vigorous’ (p = 0.91) were not significant predictors. None of the investigated variables were significantly associated with acute injuries (all p > 0.05). CONCLUSION: The PFT was found to be a significant predictor for overuse injuries in Swiss conscripts during BMT. This highlights the importance of adequate physical preparation in reducing the risk of overuse injury during BMT. The moderate correlation between the volume of vigorous physical activity and subjective readiness suggests that Swiss conscripts who engaged more in vigorous physical activity before BMT felt more ready for the military service. However, this feeling of readiness did not translate into a reduced injury risk. Only 10% of conscripts used a training application. This may indicate an unused potential of technology in supporting physical activity for BMT preparation. Military organizations could benefit from offering digital tools or training platforms to enhance conscripts’ physical readiness even before the start of BMT. [1] doi.org/10.1055/s-0031-1295445 [2] doi.org/10.1519/JSC.0000000000001106
Read CV Regina OeschgerECSS Paris 2023: CP-MH20
INTRODUCTION: Tactical athletes, including military personnel, firefighters, and police officers, face extreme conditions that impact their performance and thermoregulation. Uniform design and materials play a crucial role in heat management, influencing comfort, safety, and efficiency. Therefore, the aim of this study was to analyze the effect of uniform on skin temperature using infrared thermography. METHODS: The research was conducted with a non-probabilistic sample of 10 male soldiers, age of 27.702.71 yrs. in a controlled environment, with air temperature and relative humidity monitored using an Instrutherm® HT-270 thermohygrometer. Infrared thermography with a Flir® E76 thermal camera was used to compare skin temperatures in two conditions: with and without the Brazilian Armys new camouflage uniform. Soldiers underwent acclimatization and body temperature monitoring before measurements. Data were described using descriptive and inferential statistics. A significance level of p ≤ 0.05 was considered. RESULTS: Soldiers with Armys new camouflage uniform presented statistically significant increases in skin temperature in the right trapezius (0.87%, p=0.028) and left trapezius (1.27%, p=0.007), right chest (2.16%, p<0.001) and left chest (2.83%, p<0.001), right biceps (2.35%, p=0.002) and left biceps (3.21%, p<0.001), right costal region (2.00%, p<0.001) and left costal region (1.51%, p<0.001), as well as the left knee (6.58%, p<0.001). On the other hand, regions such as the right neck (0.03%, p=0.906) and left neck (0.24%, p=0.466) showed no significant differences. CONCLUSION: This study highlights the impact of military uniforms on skin temperature, particularly in high-metabolic muscle and joint regions. Increased heat retention was observed, emphasizing the need for uniform designs that enhance ventilation and thermal regulation. Optimizing these factors can improve comfort, performance, and operational efficiency for tactical athletes. Keywords: thermoregulation, tactical athletes, uniform. Supported by Pró-Pesquisa CADESM/DECEx/Brazilian Army, EsEFEx, Poliscan Brazil® and ThermoHuman®. References: Davis, Jon-Kyle, and Phillip A. Bishop. "Impact of clothing on exercise in the heat." Sports medicine 43.8 (2013): 695-706. Mello, Danielli Braga de; Moreira, D. G.; Neves, E. B. Termorregulação e estresse ambiental. In: Angela Nogueira Neves; Adriane Mara de Souza Muniz; Cláudia de Mello Meirelles; Danielli Braga de Mello; Laércio Camilo Rodrigues; Míriam Raquel Meira Mainenti. (Org.). Ciência aplicada ao exercício físico e ao esporte. 1ed.Curitiba: Appris, 2022, v. 1, p. 47-66. Moreira, Danilo Gomes, et al. "Thermographic imaging in sports and exercise medicine: A Delphi study and consensus statement on the measurement of human skin temperature." Journal of Thermal Biology 69 (2017): 155-162.
Read CV Manuel Sillero QuintanaECSS Paris 2023: CP-MH20