Journal of Sport and Human Performance

Evaluation of athlete load and relationship between equation variables in division I women’s lacrosse

Andrew Thornton, Brian Neville, Jennifer Bunn — Wed, 10 Jan 2024 00:00:00 +0000

Athlete monitoring companies have created an “all-in-one” variable to provide a composite score for external load, measured in arbitrary units (AU). This study aimed to evaluate the proprietary metric from VX Sport, Athlete Load (AL), for collegiate women’s lacrosse across different positions, and compare training (T) to games (G). A secondary aim was to evaluate the relationship between AL, equation variables, and session rating perceived exertion. METHODS: Global positioning system units and heart rate monitors were worn by athletes (n = 22) during T and G. RESULTS: Analyses indicated no differences (p = 0.186) between T AL (48.0 ± 5.8 AU) and G AL (57.7 ± 32.8 AU), along with no positional differences (p = 0.913). Correlation analyses between equation variables indicated strong correlations during T and G for distance (T: r= 0.72; G: r = 0.99), HID (T: r = 0.78; G: r = 0.94), and sprints (T: r = 0.85; G: r= 0.81), all p<0.001. Session rating perceived exertion was strongly correlated with G AL (r= 0.91, p<0.001). CONCLUSIONS: The data suggest there was no difference between T and G, with AL more related to the intensity of the session rather than the duration.

The use of body mass index and waist-hip ratio for prediction for autonomic recovery from exercise

Wed, 10 Jan 2024 00:00:00 +0000

Anthropometric variables have been associated with autonomic nervous system function. However, it’s unclear whether the measures of body mass index (BMI) or waist-hip ratio (WHR) can provide insight into its recovery. A total of 52 men (22.38 + 2.75 years) had resting heart rate variability (HRV) measured followed by a 30-minute submaximal exercise test, and 60-minute of HRV recovery recording. Participant data was divided into the following groups for analysis: G1: mass between 54 kg-74.6 kg; G2: mass between 75 -100.4 kg; G3: BMI between 18.6-24.9 kg/m²; G4: BMI between 25-29.9 kg/m²; G5: WHR between 0.73-0.829; G6: WHR between 0.83-0.93. When evaluating trial x time interactions, no significant interactions in the Mass groups (G1, G2) for lnrMSSD and lnHF as well as in the WHR groups (G3, G4) for lnrMSSD and lnHF were observed. The BMI groups (G5, G6) showed significant differences for lnrMSSD and lnHF. G5 recovered significantly faster at the 35-40 minute (p=0.044, 0.042), 45-50 minute (p=0.052, 0.025), and 55-60 minute (p=0.018, 0.041) time points. In conclusion, BMI was the strongest predictor for autonomic recovery following exercise. Overweight healthy physically active men presented delayed return to baseline levels.

Evaluation of WBGT guidelines to assess thermal strain during endurance running of Japanese high school students

Miyo Yokota, Ryosuke Kawabata — Wed, 10 Jan 2024 00:00:00 +0000

Background: Endurance running (ER) is a common physical test used in physical education (PE) classes in Japan. To perform ER tests safely, the Wet Bulb Globe Temperature (WBGT) index is monitored. Yet, incidences of heat-related illness are still reported every year. In this study, the thermal strain levels of the Japanese high school students during ER tests were evaluated in both environmental and physiological aspects．Methods: A total of 61 male students (Height: 169.7±4.8 cm, Weight: 60.9±10.7 kg) wearing T-shirts and shorts participated in an outdoor ER test during their PE classes (WBGT: 23.1±2.9). Volunteers ran a self-paced 1500 m on a track. On test days, a questionnaire (e.g., hydration and exercise habits etc.) was administered prior to the running event. Real-time heart rate (HR) of the students and environmental condition data were recorded. The collected data were then used to estimate core temperatures and physiological strain levels (PSL) using a two-node thermal model. Results: Although the WBGT was classified as safe to exercise, many students’ HR increased to 200 bpm, and their PSL ranged from moderate to high, suggesting a significant risk for heat-related illness. The ER time was significantly associated with exercise habits of the students and WBGT. Conclusions: Current operations for ER tests in Japan need to be revisited to prevent heat illness and injury. Using both WBGT and thermal modeling improves understanding of the thermal status of runners and helps to mitigate the risk for heat illnesses.

Modeling thermophysiological responses during head-in and head-out whole-body water immersion

Irena Yermakova, Maria Ntoumani, Adam W Potter — Thu, 15 Feb 2024 00:00:00 +0000

Mathematical representations of humans that are capable of predicting thermophysiological responses provide valuable tools for mitigating health risks during exposures to extreme environments. Humans work or operate in a wide range of conditions, from extreme heat, freezing cold, to partially or fully immersed in water. Each of these conditions presents unique heat exchange relationships that make mathematically modeling responses to each slightly different. Methods: A validated mathematical model was used to describe human thermal responses to whole-body water immersion specific to the differences between head-in and head-out conditions. Four different immersion conditions in 17°C water were used (low activity with head out and head in, and moderate activity with head-out and head-in) to describe these responses. Results: Modeling showed a moderate increase in shivering rate and water-based convective heat loss that was coupled with significant differences in brain temperature and an observable difference in internal core body temperature during head-in conditions. This work highlights the significance in differences between head-in and head-out during whole-body water immersion.

Dedication:

This work is specifically dedicated to the memory of Dr. Leslie D. Montgomery (1939-2022). His published work on thermoregulatory responses to humans during immersion were of significant importance to advancing this field of science. However, perhaps more notable was his mentorship and dedication to the well-being of others that has helped advance scientists and people generally.

Evolution of attack efficacy and execution in women’s volleyball according to age group and level of competition

Carlos Echeverria, Enrique Ortega, Jose M Palao — Fri, 01 Mar 2024 00:00:00 +0000

The aim was to determine the evolution of the attack regarding the way of execution and efficacy level according to the age group and level of competition in female volleyball. The sample was composed of 48 matches in U14, U16, U18, senior 2nd national division, senior 1st national division, and senior international level. The studied variables were the age group and level of competition, game phase, attack technique, attack zone, attack destination, attack tempo, and attack efficacy. At higher levels of competition: a) the number of quick spikes increases, b) the efficacy of the high-ball spike in the side-out phase increases, c) there is a higher number of attacks from back-row players, and d) the efficacy of front-row spikes in the side-out phase increases.