Suchergebnisse

Introduction: This study was conducted to determine what physical and physiological characteristics contribute to the performance of an urban operation casualty evacuation (UO) and its predictive test, FORCE combat (FC) and describe the metabolic demand of the UO in female soldiers. Methods: Seventeen military members (9 M and 8 F) completed a loaded walking maximal aerobic test, the UO and FC. Heart rate reserve (HRR) and completion time were used as efficiency/performance measures. Oxygen consumption (VO2) was directly measured for UO on five female participants with a portable indirect calorimetry system, and analysed using descriptive statistics. Stepwise multiple regression analysis were used to determine the contribution of the non-modifiable (age, sex, height) and modifiable characteristics (lean body mass to dead mass ratio (LBM:DM), VO2max corrected for load (L.VO2max), peak force (PF) measured on an isometric mid-thigh pull (IMTP) and medicine ball chest throw distance (Dist) on to the performance of each exercise. Results: LBM:DM and PF were the only factors included in the stepwise regression model for UO, predicting 70% of UO performance (p<0.01). For FC, L.VO2max only was included in the stepwise regression model predicting 54% of FC performance (p<0.01). Sex, age and height were not included in the regression model. The average metabolic cost of UO was 21.4 mL of O2*kg-1*min-1 in female soldiers while wearing PPE Conclusion: This study showed that modifiable factors such as body composition, PF on IMTP and L.VO2max are key contributors to performance on UO and FC performance.

Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure (EE). Thirteen participants (seven women) were monitored during three discrete periods of military training for nine days on-camp (CAMP), five days' field exercise (FEX) and nine days of a mixture of the two (MIX). Dietary intake was measured using researcher-led food weighing and food diaries and EE was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4600kcal·d-1) and women (3500kcal·d-1) during CAMP (men: -16%; women -9%), FEX (men: -33%; women: -42%) and MIX (men and women both -34%). Carbohydrate intake of men and women were below guidelines (6g·kg·d-1) during CAMP (men: -10%; women: -9%), FEX (men: -18%; women: -37%), and MIX (men: -3%; women: -39%), respectively. Protein intake was above guidelines (1.2kcal·kg·d-1) for men and women during CAMP (men: 48%; women: 39%) and MIX (men: 9%; women: 3%), but below guidelines during FEX (men: -13%; women: -27%). Energy and macronutrient intake during CAMP centred around mealtimes with a discernible sleep/wake cycle for EE. During FEX, energy and macronutrient intake were individually variable and EE was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimise performance and adaptations during military training.

Military training is characterised by high daily energy expenditures (EE) which are difficult to match with energy intake (EI) potentially resulting in negative energy balance (EB) and low energy availability (EA). The aim of this study was to quantify EB and EA during British Army Officer Cadet (OC) training. Thirteen (seven women) OCs (mean ± SD: age 24 ± 3 years) volunteered to participate. EB and EA were estimated from EI (weighing of food and food diaries) and EE (doubly-labelled water) measured in three periods of training; nine days on-camp (CAMP), a five-day field exercise (FEX) and a nine-day mixture of both (MIX). Variables were compared by condition and gender with a repeated measures ANOVA. Negative EB was greatest during FEX (-2197 ± 455 kcal·d-1) compared with CAMP (-692 ± 506 kcal·d-1; p<0.001) and MIX (-1280 ± 309 kcal·d-1; p<0.001). EA was greatest in CAMP (23 ± 10 kcal·d-1) compared with FEX (1 ± 16 kcal·d-1; p=0.002) and MIX (10 ± 7 kcal·d-1; p=0.003), with no apparent difference between FEX and MIX (p=0.071). Irrespective of condition, there were no apparent differences between gender in EB (p=0.375) or EA (p=0.385). These data can be used to inform evidenced-based strategies to manage EA and EB during military training and enhance the health and performance of military personnel.

Wearable physical activity (PA) monitors have improved the ability to estimate free-living total energy expenditure (TEE) but their application during arduous military training alongside more well-established research methods has not been widely documented. This study aimed to assess the validity of two wrist-worn activity monitors and a PA log against doubly-labelled water (DLW) during British Army Officer Cadet (OC) training. For 10 days of training, twenty (10 male and 10 female) OCs (mean ± SD: age 23 ± 2 years, height 1.74 ± 0.09 m, body mass 77.0 ± 9.3 kg) wore one research-grade accelerometer (GENEActiv, Cambridge, UK) on the dominant wrist, wore one commercially-available monitor (Fitbit SURGE, USA) on the non-dominant wrist and completed a self-report PA log. Immediately prior to this 10-day period, participants consumed a bolus of DLW and provided daily urine samples, which were analysed by mass spectrometry to determine TEE. Bivariate correlations and limits of agreement (LoA) were employed to compare TEE from each estimation method to DLW. Average daily TEE from DLW was 4112 ± 652 kcal·day against which the GENEActiv showed near identical average TEE (mean bias ± LoA: -15 ± 851 kcal day ) while Fitbit tended to underestimate (-656 ± 683 kcal·day ) and the PA log substantially overestimate (+1946 ± 1637 kcal·day ). Wearable physical activity monitors provide a cheaper and more practical method for estimating free-living TEE than DLW in military settings. The GENEActiv accelerometer demonstrated good validity for assessing daily TEE and would appear suitable for use in large-scale, longitudinal military studies.