Title

Effects of Load Carriage and Fatigue on Gait Coordination and Variation in Healthy Males

Publication Date

5-2012

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Exercise and Sport Studies, Biophysical Studies

Department

Kinesiology

Major Advisor

Eric Dugan, Ph.D.

Abstract

INTRODUCTION: In cyclic tasks such as gait, a pattern of limb segment and joint orientation emerges, revealing a coordination pattern that is repeated for efficiency of task completion. The body's ability to temporarily deviate from that pattern allows for adaptation to perturbations such as load carriage and fatigue. Too much or too little variation in the coordination pattern can lead to injuries; to prevent injury a system will sometimes switch and utilizes a new coordination pattern. Similarly, a completely novel coordination pattern may also be hazardous because the body is unfamiliar with the orientation. Gathering basic information on when gait coordination changes occur could lead to a better understanding of lower limb injury mechanisms. The awareness of gait pattern alteration can initiate inquiries into how to adjust such a coordination change occurrence and possibly injury prevention. This study will be used to examine the effects that introducing load and fatigue has on lower limb gait coordination and the variation of that coordination. Using mean absolute relative phase (MARP) as a measurement of coordination and deviation phase (DP) as a measure of variation within a coordinative strategy the changes in inter- and intra-limb orientation will be compared across conditions to determine if coordination or variation is altered due to the perturbations presented to the system. It is hypothesized that with the introduction of load and fatigue the system will not change. METHODS: Twenty three male subjects were recruited from university student population convenience sampling. Following Army recruitment patterns, participants were 18-27 years of age and had a body mass index no greater than 28. Other exclusion criteria included current or previous military enlistment and current or previous musculoskeletal injury. Both an aerobic fitness test (VO2PEAK) and a lower body muscular strength test (1RM leg press) were administered. MARP and DP were assessed during stationary treadmill walking both with and without wearing a 35kg ruck sack measured before and after completing a lower limb fatiguing protocol. Data were analyzed in the following four conditions: Unloaded-Unfatigued (UU), Loaded- Unfatigued (UL), Loaded-Fatigued (LF), Unloaded -Fatigued (UF). RESULTS AND DISCUSSION: A repeated measures analysis of variance test (ɑ= 0.05) was utilized to test for differences in MARP and DP within participants across testing conditions. No significant changes in MARP were observed for any condition. Inter-limb DP at the ankle was significantly greater for LF than for UU and UF (Table 1). Similar significance was seen at the knee with LF being greater than UU and UP (Table 1). Only the shank-shank pairing showed any significant variation differences, with UU being less than LF (Table 1). Participants tended to increase the variability in the chosen pattern instead of utilizing a new coordination pattern. The results suggest that with the combination of fatigue and load carriage, the variation in coordination is significantly higher than when not carrying the load no matter the state of fatigue. CONCLUSIONS: The development of injury interventions, especially with the application of load and fatigue, can utilize the information found in this investigation. Future research should look further into the implications of variation changes with prolonged weight bearing gait tasks to fatigue.

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