Minimal Additional Weight of Combat Equipment Alters Air Assault Soldiers’ Landing Biomechanics

Abstract

The additional weight of combat and protective equipment carried by soldiers on the battlefield and insufficient adaptations to this weight may increase the risk of musculoskeletal injury. The objective of this study was to determine the effects of the additional weight of equipment on knee kinematics and vertical ground reaction forces (VGRF) during two-legged drop landings. We tested kinematics and VGRF of 70 air assault soldiers performing drop landings with and without wearing the equipment. Maximum knee flexion angles, maximum vertical ground reaction forces, and the time from initial contact to these maximum values all increased with the additional weight of equipment. Proper landing technique, additional weight (perhaps in the form of combat and protective equipment), and eccentric strengthening of the hips and knees should be integrated into soldiers' training to induce musculoskeletal and biomechanical adaptations to reduce the risk of musculoskeletal injury during two-legged drop landing maneuvers.

Lower limb flexion posture relates to energy absorption during drop landings with soldier-relevant body borne loads

“…forces (Zhang et al, 2000). The current outcomes, in agreement with Sell et al (2010), support the contention that a soldier transporting body borne load experiences significantly greater peak vertical ground reaction force during a drop landing. In the current study, load carriers increased peak vertical GRF 9% and 17% when landing with the soldier-relevant medium and heavy loads, as compared to the light load, respectively.…”

“…Considering both recreationally active (Kulas et al, 2008) and military (Sell et al, 2010) participants exhibit greater knee flexion while landing with light body borne loads, increasing knee flexion when landing with soldier-relevant body borne loads should be an attainable goal to increase energy absorption and decrease the risk of musculoskeletal injury. But, to date, it remains unanswered how landing with body borne loads, especially soldier-relevant load configurations, increases the demand on the knee musculature, and whether greater knee flexion during such landings translates to greater energy absorption.…”

“…During drop landings with a light body borne load (10% and 18% of body weight, respectively), there is a significant increase in maximal vertical ground reaction force and demand placed on the musculoskeletal system (Sell et al, 2010;Kulas et al, 2008). However, to date, little is known about how the body borne loads, between 20 kg and 40 kg, that soldiers commonly carry during military activities increase the ground reaction force and demand place on the musculoskeletal system during drop landings (Task Force Devil Combined Arms Assessment Team, 2003).…”

“…Landing with body borne load increases the demand placed on the musculoskeletal system (Sell et al, 2010;Kulas et al, 2008), but improving the biomechanical profile of lower extremity, such as using more knee flexion during landing, may increase the amount of energy the knee can safely absorb and decrease the risk of musculoskeletal injury e e.g., ligamentous sprain or rupture. Considering both recreationally active (Kulas et al, 2008) and military (Sell et al, 2010) participants exhibit greater knee flexion while landing with light body borne loads, increasing knee flexion when landing with soldier-relevant body borne loads should be an attainable goal to increase energy absorption and decrease the risk of musculoskeletal injury.…”

Catastrophizing and Pain in Military Personnel

“…Heavy body armor, vibratory conditions, and other combat factors likely lead to these musculoskeletal issues in soldiers [4][5][6]. While body armor certainly protects against missiles and blasts, the protection comes at a biomechanical cost.…”