Changes in combat task performance under increasing loads in active duty marines.
U.S. Marines perform mission tasks under heavy loads which may compromise performance of combat tasks. However, data supporting this performance decrement are limited.


OBJECTIVE
The aim of this study was to determine the effects of load on performance of combat-related tasks.


METHODS
Subjects (N=18) ran a modified Maneuver Under Fire ([MANUF], 300 yards [yd] total: two 25-yd sprints, 25-yd crawl, 75-yd casualty drag, 150-yd ammunition can carry, and grenade toss) portion of the U.S. Marine Corps Combat Fitness Test under 4 trial conditions: neat (no load), 15%, 30%, and 45% of body weight, with a shooting task pre- and post-trial.


RESULTS
There was a significant increase in total time to completion as a function of load (p<0.0001) with a relationship between load and time (r=0.592, p<0.0001). Pre- to post-MANUF shot accuracy (p=0.005) and precision (p<0.0001) was reduced.


CONCLUSIONS
Short aerobic performance is significantly impacted by increasing loads. Marksmanship is compromised as a function of fatigue and load. These data suggest that loads of 45% body weight increase time to cover distance and reduce the ability to precisely hit a target.
Marine Expeditionary Rifle Squad, Marine Corps Systems Command, 2200 Lester Street, Quantico, VA 22134-6050.
Rebecca L
RL
Jaworski
Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road-Building 328-208C, San Diego, CA 92106.
Andrew
A
Jensen
Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road-Building 328-208C, San Diego, CA 92106.
Brenda
B
Niederberger
Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road-Building 328-208C, San Diego, CA 92106.
Robert
R
Congalton
Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road-Building 328-208C, San Diego, CA 92106.
Karen R
KR
Kelly
D000328:Adult; D005221:Fatigue / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008889:Military Personnel; D010809:Physical Fitness / Q000502:physiology*; D013647:Task Performance and Analysis; D014481:United States; D016474:Weight-Bearing / Q000502:physiology*