Category: International; Military and Veterans Affairs; Athlete Development & Sports Rehabilitation
Objective :
To investigate the effect of a two hour 20.5 kg load carriage task on shoulder neuromuscular functions compared to unloaded walking. Also, to investigate groups needed recovery time. We hypothesized: that “load group” would show a decrement and longer recovery after 2 hours of walking compared to “no load group”.
Design :
Cohort study
Setting : Laboratory
Participants (or Animals, Specimens, Cadavers) :
A convenient sample of twenty-six healthy participants, divided into two equal groups. Ten females, 16 males, the mean and standard deviation for both groups(age 25±5.8years; weight 70±10.5kg; height 173±9.6cm). Subjects were excluded who had recent shoulder injuries, or previous medical and neurological problems.
Interventions :
Data were collected from the right shoulder at baseline, immediately post walking task and at subsequent intervals over the next 30 minutes recovery.
Main Outcome Measure(s) :
Dominant arm abduction strength and endurance, axillary nerve amplitude, and shooting accuracy, all assessed at baseline and sequentially post walking through recovery. Subjects walked for 2 hours on leveled treadmill carrying a 20.5kg backpack for “Load group” at a velocity of(5.5-7km/h). One-way repeated measures ANOVA followed by Bonferroni post-hoc analysis if significant difference exists.
Results :
Strength decreased in load group by 19%(p=0.005) and recovered at 30 minutes, with no change following no load walking(p=0.314). Endurance reduced in load group by 9%(p=0.05) and recovered after 10 minutes, with no change following no load walking(p=0.274). No significant change exists in nerve amplitude and accuracy. No significant difference between groups across all measures.
Conclusions :
Walking with a heavy backpack for 2 hours reduced significantly shoulder strength. Carrying heavier loads and walking for longer periods, especially in a military population, will affect the performance and might increase the risk of injuries if recovery not allowed.
Muataz Almaddah
– Ph.D Candidate, University of Kentucky, Lexington, KentuckyArthur Nitz
– Proffesor, University of Kentucky, Lexington, KentuckyJohn Abt
– Associate Professor Director, Sports Medicine Research Institute, University of Kentucky, Lexington, KentuckyBabak Bazrgari
– Associate Professor, F. Joseph Halcomb III, M.D. Department of Biomedical Engineering,, University of Kentucky, Lexington, KentuckyTim Uhl
– Director of Musculoskeletal Laboratory Professor, University of Kentucky, Lexington, Kentucky