Application of Energy Cost Algorithms for Load Carriage to Field Data

Abstract

IntroductionThis study is a continuation of our research (Santee et al., 2001) to quantify the metabolic cost of load carriage by expanding the database to include load carriage under field conditions. The primary purpose of the study was to obtain data under field conditions and use it to validate predictive algorithms developed from our previous laboratory study. At present, predictive thermoregulatory models and simulations, including SCENARIO (Kraning and Gonzalez, 1997), the Integrated Unit Soldier Simulation (Ramirez and Hoffman, 1994) and the Close Action ENvironment CAEN (Demczuk, 1998) simulation are limited in their ability to accurately predict energy expenditure for locomotion over negatively sloped terrain. Our algorithms provide those additional energy cost estimates.The following introductory comments are intended to illustrate the complexity of load carriage, especially under field conditions. As these factors simultaneously impact the energy requirements for load carriage, the data presented in this study cannot wholly discriminate between these factors. Thus while we can speculate on the impact of different factors, the study is focused on the relative fit of the algorithm predictions to the observed data.The problems with downhill movement, including load carriage, are well known. Earlier investigators (Pimental and Pandolf, 1979; Magaria, 1968;Minetti et al., 1998, Wanta et al., 1993 had observed that the minimum energy requirement for walking occurred on negative slopes. The principal problem is that multiple forces are acting upon the same muscles. A simple explanation is that 2 factors are involvedgravity or negative work involving vertical displacement, and metabolic costs including maintenance or baseline metabolism, the muscular work to move or accelerate the body forward, and energy expanded to maintain stability. Stability is generally thought of as braking to maintain control at increasing downward speeds, but there may be some cost associated with controlling lateral deflection.In terms of biomechanics, the problem involves eccentric work in which opposing forces act simultaneously on the same muscles. Due to the relative complexity of the multiple factors, relatively few models have been proposed. Minetti et al. (2002) published models for up-and downhill walking and running, but their emphasis is on competitive events without significant loads. Laursen et al. (2000) tested a biomechanical model for up and downhill walking with and without hand-held loads on a treadmill. DemczukJournal of the Human-Environmental System Vol. 6; No. 2: 69-76, 2003 Application of Energy Cost Algorithms for Load Carriage to Field Data AbstractThis study measured the energy requirements for load carriage on uphill, level and downhill grades. These field data were used to test our algorithms for estimating the energy cost of load carriage. Volunteers carried pack loads of 0 kg, 13.6 kg or 27.2 kg as they walked on level and downhill grades of 0%, 4%, 8.6% and 12% at 1.34 m · s ؊1 . Subjects attempt...

Modeling the Metabolic Costs of Heavy Military Backpacking

“…Subsequently, we conducted a k-fold cross-validation for an initial examination of the generalizability of the LCDA backpacking equation. Lastly, we validated the LCDA backpacking equation against seven historical reference data sets (13,(17)(18)(19)(20)(21)(22).…”

“…External validation. We externally validated the LCDA backpacking equation on data collected in 81 healthy US Army soldiers and civilians (17 women, 64 men) from seven historical reference studies (13,(17)(18)(19)(20)(21)(22). Each study involved respiratory gas exchange measurement for indirect calorimetry during steady-state treadmill walking with backpacks in temperate laboratory conditions.…”

“…Each study involved respiratory gas exchange measurement for indirect calorimetry during steady-state treadmill walking with backpacks in temperate laboratory conditions. All data from each of the seven studies were analyzed excluding trials that involved alternative modes of exercise (19,20,29), uphill or downhill slope walking (22), or abnormal load distributions (13). Table 1 summarizes the participants and conditions from each study.…”

“…FIGURE 2-Paired differences between estimated and measured metabolic rates (M ˙) across measured M ˙, walking speed, and backpack load from historical reference study data(13,(17)(18)(19)(20)(21)(22). Dashed line, line of zero difference.…”

The Pandolf load carriage equation is a poor predictor of metabolic rate while wearing explosive ordnance disposal protective clothing

“…age, height, mass) and extrinsic factors (e.g. terrain, gradient, load) (American College Of Sports Medicine 2014, Epstein, Stroschein, and Pandolf 1987, Givoni and Goldman 1971, Pandolf, Givoni, and Goldman 1977 Metabolic cost of EOD ensemble Santee et al 2001, Santee, Small, andBlanchard 2003). The most commonly applied metabolic prediction equation for load carriage during standing and locomotion was originally developed by Givoni and Goldman (1971) and was subsequently updated by Pandolf, Givoni, and Goldman (1977).…”