Influence of Soldiers' Cardiorespiratory Fitness on Physiological Responses and Dropouts During a Loaded Long-distance March.

Oeschger, Regina; Roos, Lillian; Wyss, Thomas; Buller, Mark J.; Veenstra, Bertil J.; Gilgen-Ammann, Rahel (2022). Influence of Soldiers' Cardiorespiratory Fitness on Physiological Responses and Dropouts During a Loaded Long-distance March. Military Medicine, 188(7-8), e1903-e1909. Oxford University Press 10.1093/milmed/usab540

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Introduction: In military service, marching is an important, common, and physically demanding task. Minimizing dropouts, maintaining operational readiness during the march, and achieving a fast recovery are desirable because the soldiers have to be ready for duty, sometimes shortly after an exhausting task. The present field study investigated the influence of the soldiers' cardiorespiratory fitness on physiological responses during a long-lasting and challenging 34 km march. Materials and methods: Heart rate (HR), body core temperature (BCT), total energy expenditure (TEE), energy intake, motivation, and pain sensation were investigated in 44 soldiers (20.3 ± 1.3 years, 178.5 ± 7.0 cm, 74.8 ± 9.8 kg, body mass index: 23.4 ± 2.7 kg × m-2, peak oxygen uptake ($\dot{\rm{V}}$O2peak): 54.2 ± 7.9 mL × kg-1 × min-1) during almost 8 hours of marching. All soldiers were equipped with a portable electrocardiogram to record HR and an accelerometer on the hip, all swallowed a telemetry pill to record BCT, and all filled out a pre- and post-march questionnaire. The influence of aerobic capacity on the physiological responses during the march was examined by dividing the soldiers into three fitness groups according to their $\dot{\rm{V}}$O2peak. Results: The group with the lowest aerobic capacity ($\dot{\rm{V}}$O2peak: 44.9 ± 4.8 mL × kg-1 × min-1) compared to the group with the highest aerobic capacity ($\dot{\rm{V}}$O2peak: 61.7 ± 2.2 mL × kg-1 × min-1) showed a significantly higher (P < .05) mean HR (133 ± 9 bpm and 125 ± 8 bpm, respectively) as well as peak BCT (38.6 ± 0.3 and 38.4 ± 0.2 °C, respectively) during the march. In terms of recovery ability during the break, no significant differences could be identified between the three groups in either HR or BCT. The energy deficit during the march was remarkably high, as the soldiers could only replace 22%, 26%, and 36% of the total energy expenditure in the lower, middle, and higher fitness group, respectively. The cardiorespiratory fittest soldiers showed a significantly higher motivation to perform when compared to the least cardiorespiratory fit soldiers (P = .002; scale from 1 [not at all] to 10 [extremely]; scale difference of 2.3). A total of nine soldiers (16%) had to end marching early: four soldiers (21%) in the group with the lowest aerobic capacity, five (28%) in the middle group, and none in the highest group. Conclusion: Soldiers with a high $\dot{\rm{V}}$O2peak showed a lower mean HR and peak BCT throughout the long-distance march, as well as higher performance motivation, no dropouts, and lower energy deficit. All soldiers showed an enormous energy deficit; therefore, corresponding nutritional strategies are recommended.

Item Type:	Journal Article (Original Article)
Division/Institute:	Swiss Federal Institute of Sports Magglingen SFISM > EHSM - Lehre und Sportpädagogik > Evaluation Swiss Federal Institute of Sports Magglingen SFISM > EHSM - Lehre und Sportpädagogik > Monitoring
Name:	Oeschger, Regina; Roos, Lillian; Wyss, Thomas; Buller, Mark J.; Veenstra, Bertil J. and Gilgen-Ammann, Rahel
ISSN:	0026-4075 (Print) 1930-613X (Online)
Publisher:	Oxford University Press
Language:	English
Submitter:	Sabina Wolfensberger
Date Deposited:	30 Jun 2023 08:48
Last Modified:	30 Jul 2023 01:38
Publisher DOI:	10.1093/milmed/usab540
Related URLs:	Publication
PubMed ID:	35015894
Uncontrolled Keywords:	Sport Monitoring
ARBOR DOI:	10.24451/arbor.19381
URI:	https://arbor.bfh.ch/id/eprint/19381