Modeling the Metabolic Costs of Heavy Military Backpacking

Abstract

IntroductionExisting predictive equations underestimate the metabolic costs of heavy military load carriage. Metabolic costs are specific to each type of military equipment, and backpack loads often impose the most sustained burden on the dismounted warfighter.PurposeThis study aimed to develop and validate an equation for estimating metabolic rates during heavy backpacking for the US Army Load Carriage Decision Aid (LCDA), an integrated software mission planning tool.MethodsThirty healthy, active military-age adults (3 women, 27 men; age, 25 ± 7 yr; height, 1.74 ± 0.07 m; body mass, 77 ± 15 kg) walked for 6–21 min while carrying backpacks loaded up to 66% body mass at speeds between 0.45 and 1.97 m·s−1. A new predictive model, the LCDA backpacking equation, was developed on metabolic rate data calculated from indirect calorimetry. Model estimation performance was evaluated internally by k-fold cross-validation and externally against seven historical reference data sets. We tested if the 90% confidence interval of the mean paired difference was within equivalence limits equal to 10% of the measured metabolic rate. Estimation accuracy and level of agreement were also evaluated by the bias and concordance correlation coefficient (CCC), respectively.ResultsEstimates from the LCDA backpacking equation were statistically equivalent (P < 0.01) to metabolic rates measured in the current study (bias, −0.01 ± 0.62 W·kg−1; CCC, 0.965) and from the seven independent data sets (bias, −0.08 ± 0.59 W·kg−1; CCC, 0.926).ConclusionsThe newly derived LCDA backpacking equation provides close estimates of steady-state metabolic energy expenditure during heavy load carriage. These advances enable further optimization of thermal-work strain monitoring, sports nutrition, and hydration strategies.

Metabolic and ruck performance effects of a novel, light‐weight, energy‐dense ketogenic bar

“…When accounting for all the physiological parameters and ruck grade, predictive ruck metabolic equations revealed that the average participant in this study expended 270 kcal/h (Looney et al, 2022).…”

Metabolic Costs of Walking with Weighted Vests

“…Design. The design of the present study mirrored that of our previous article on military backpack loading (13) with few exceptions. Steady-state metabolic rate (M ˙) data were collected from healthy, active military-age men and women at walking speeds up to 1.97 m•s −1 while unloaded (0% body mass) and when carrying three vest-borne loads (22%, 44%, and 66% body mass).…”

“…Metabolic rate (M ˙) is divided into a resting component (M ˙Rest ) as well as two active components for standing (M ˙Stand ) and walking (M ˙Walk ) multiplied by a load factor (load). The M ˙Walk component includes a terrain coefficient for different walking surfaces (9,10), two level walking terms (11,13), and a graded walking term (12). The load factor consists of individual terms for different types of carried equipment, including backpack (13) and vest-borne loads.…”

“…In recent years, US Army Research Institute of Environmental Medicine researchers crafted new metabolic equations for the LCDA that focused on the impacts of difficult terrain (9,10), standing and walking from slow to fast speeds (11), steep uphill and downhill slopes (12), and the loads imposed by modern military backpacks (13). Although military backpack loads are part of the model, loads distributed across the torso such as double packs and vest-worn loads were not considered, even though they contribute the largest mass to a dismounted warfighter's total fighting load (14).…”

Estimating Metabolic Energy Expenditure During Level Running in Healthy, Military-Age Women and Men

“…US Army doctrine on work/rest guidance is based on the inclusion of Ṁ estimates into sophisticated thermophysiological models that forecast core body temperature changes for a typical warfighter depending on the environmental conditions (63,78). Although recent studies focused on deriving optimized walking equations for modern military personnel (53)(54)(55)69,70), there has yet to be a concerted effort to develop a similar series of equations for running.…”