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Soldier Performance and Heat Strain During Evaluation of a Combat Fitness Assessment in Northern Australia

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The Australian Defence Force is improving the operational specificity of combat fitness assessment CFA. A prototype CFA trial, conducted using 64 male soldiers of 3 Brigade, Townsville, allowed for the evaluation of both the CFA and the severity of heat strain experienced during physical training and assessment in northern Australia. Maximal aerobic VO2max and anaerobic peak and 30-s mean power were estimated by Beep and Wingate tests, respectively. Peak and 30-s mean powers and estimated VO2max were 12.7 -1.9, 9.3 -1.0 and 45.5 -6.0 mL-min-1kg-1, respectively. Of 31 soldiers marching 20 km with 35 kg load, 9 29 finished within the 4 hours available WBGT 27.60C. Of 51 soldiers marching 5 km with 20 kg load, 47 92 finished within 55 mins WBGT27.10C. Heart rate HR, VO2, gastrointestinal Tgi and skin Tsk temperature were recorded during the marches n5-19. Body weight, urine composition and volume and psychophysical indices of strain were obtained before and after the marches n9-50. At completion of the 5 and 20 km marches, high strain was evident from high HR mean 83 5 KM 89 20 KM of HRmax, Tgi 38.60C 39.10C, perceived body temperature hot and very hot and exertion very hard and hard, and by instances of urinary protein and erythrocytes. The present estimates of VO2max indicate that the ability of these infantry to operate in the tropics may be appreciably limited by their aerobic fitness. Further testing of soldiers aerobic fitness will help determine the extent of this problem. Similarly, some soldiers experience very high heat strain during training and assessment. Endurance-related assessments should be conducted with personnel being rested and well hydrated, and with performance being indexed to environmental heat stress. Finally, heat strain can be monitored using gastro-intestinal radio-pill thermometry where appropriate.

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  • Medicine and Medical Research
  • Stress Physiology
  • Military Forces and Organizations

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