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

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

Validation of ambulatory monitoring devices to measure energy expenditure and heart rate in a military setting

Objectives.; To investigate the validity of different devices and algorithms used in military organizations worldwide to assess physical activity energy expenditure (PAEE) and heart rate (HR) among soldiers.; Design.; Device validation study.; Methods; . Twenty-three male participants serving their mandatory military service accomplished, firstly, nine different military specific activities indoors, and secondly, a normal military routine outdoors. Participants wore simultaneously an ActiHeart, Everion, MetaMax 3B, Garmin Fenix 3, Hidalgo EQ02, and PADIS 2.0 system. The PAEE and HR data of each system were compared to the criterion measures MetaMax 3B and Hidalgo EQ02, respectively.; Results; . Overall, the recorded systematic errors in PAEE estimation ranged from 0.1 (±1.8) kcal.min; -1; to -1.7 (±1.8) kcal.min; -1; for the systems PADIS 2.0 and Hidalgo EQ02 running the Royal Dutch Army algorithm, respectively, and in the HR assessment ranged from -0.1 (±2.1) b.min; -1; to 0.8 (±3.0) b.min; -1; for the PADIS 2.0 and ActiHeart systems, respectively. The mean absolute percentage error (MAPE) in PAEE estimation ranged from 29.9% to 75.1%, with only the Everion system showing an overall MAP

The Wearing Comfort and Acceptability of Ambulatory Physical Activity Monitoring Devices in Soldiers

OCCUPATIONAL APPLICATIONS We investigated the wearing comfort of nine devices for monitoring physical activity in a military context. In general, the questionnaire-based survey revealed that the devices were highly acceptable. For long-term monitoring of physical activity in soldiers (&gt;5 days), slightly more participants (85.2%) found that sensors not located at the chest would be more acceptable compared to the chest-worn devices (66.7%). More specifically, our results suggest that devices placed on or around the upper arm, the hip, or the shoe will be preferred over devices worn around the wrist or on or around the chest in a military context. The placement of physical activity monitoring devices around the chest, in particular, can be expected to lead to discomfort due to incompatibilities with military equipment. TECHNICAL ABSTRACT Background: Military organizations use body-worn devices for ambulatory monitoring of physical activity in soldiers. However, little is known regarding the wearing comfort and acceptability of ambulatory monitoring devices as used in the military context. Purpose: To investigate the wearing comfort and acceptability of nine body-worn devices for monitoring physical activity in soldiers. Methods: A total of 27 male volunteers wore three randomly assigned devices simultaneously for one day of basic military training. The participants then completed a questionnaire designed to assess comfort and acceptability. Results: Devices worn on or around the chest were associated with lower wearing comfort and acceptability scores (overall scores of 59.7, 70.8, and 80.9 for Hidalgo EQ02, TICKR X, and ActiHeart, respectively). Devices worn around the wrist, Mio FUSE (80.9), GENEActiv (81.3), and fenix 3 (85.3), had mid-range scores. The highest scores were obtained for the devices Blue Thunder, worn on the shoe (85.5), Axiamote PADIS 2.0, worn on the hip and the backpack (88.9), and Everion, worn on the upper arm (90.1). Conclusions: Body-worn devices for monitoring physical activity are well-accepted in soldiers. The differences between the devices were small for several parameters. Nevertheless, devices that are attached to, or around, the chest, were typically perceived as having a slightly more negative impact on the body. Both wrist- and chest-worn devices received some reports of interfering with military equipment or military tasks

An evaluation of measurement systems estimating gait speed during a loaded military march over graded terrain

This study aimed to evaluate the accuracy of three measurement systems estimating gait speed during a loaded military march over graded terrain. Systems developed by the Swiss and Netherlands Armed Forces and a commercial wrist-based device were evaluated in comparison to a Global Positioning System. The first part of the paper focuses on the development of the Dutch system, where speed is estimated from a chest worn accelerometer and body measurements. For this validation study 36 subjects were walking or running 13 laps of 200m at different speeds. Results showed that walking and running speed can be estimated with a R2adj of 0.968 and 0.740, respectively. In the second part of this paper, data from 64 soldiers performing a 35 km march were used to evaluate the accuracy of three measurement systems in estimating speed. Data showed that estimating gait speed with a single accelerometer can be accurate for military activity, even without prior individual calibration measurements. However, predictions should be corrected for confounders such as body size and shoe type to be accurate. Both, downhill and uphill walking led to changes in gait characteristics and to an overestimation of speed by up to 10%. Correcting for slope or gradient using altimetry in future algorithms/experiments could improve the estimation of gait speed

The Wearing Comfort and Acceptability of Ambulatory Physical Activity Monitoring Devices in Soldiers

OCCUPATIONAL APPLICATIONS We investigated the wearing comfort of nine devices for monitoring physical activity in a military context. In general, the questionnaire-based survey revealed that the devices were highly acceptable. For long-term monitoring of physical activity in soldiers (&gt;5 days), slightly more participants (85.2%) found that sensors not located at the chest would be more acceptable compared to the chest-worn devices (66.7%). More specifically, our results suggest that devices placed on or around the upper arm, the hip, or the shoe will be preferred over devices worn around the wrist or on or around the chest in a military context. The placement of physical activity monitoring devices around the chest, in particular, can be expected to lead to discomfort due to incompatibilities with military equipment. TECHNICAL ABSTRACT Background: Military organizations use body-worn devices for ambulatory monitoring of physical activity in soldiers. However, little is known regarding the wearing comfort and acceptability of ambulatory monitoring devices as used in the military context. Purpose: To investigate the wearing comfort and acceptability of nine body-worn devices for monitoring physical activity in soldiers. Methods: A total of 27 male volunteers wore three randomly assigned devices simultaneously for one day of basic military training. The participants then completed a questionnaire designed to assess comfort and acceptability. Results: Devices worn on or around the chest were associated with lower wearing comfort and acceptability scores (overall scores of 59.7, 70.8, and 80.9 for Hidalgo EQ02, TICKR X, and ActiHeart, respectively). Devices worn around the wrist, Mio FUSE (80.9), GENEActiv (81.3), and fenix 3 (85.3), had mid-range scores. The highest scores were obtained for the devices Blue Thunder, worn on the shoe (85.5), Axiamote PADIS 2.0, worn on the hip and the backpack (88.9), and Everion, worn on the upper arm (90.1). Conclusions: Body-worn devices for monitoring physical activity are well-accepted in soldiers. The differences between the devices were small for several parameters. Nevertheless, devices that are attached to, or around, the chest, were typically perceived as having a slightly more negative impact on the body. Both wrist- and chest-worn devices received some reports of interfering with military equipment or military tasks