T.J. Anderson, D.M. Lawson, K. Taylor, M. Thompson , J. Seegmiller

University of Idaho Moscow, ID

Little is known about the relation between asymmetrical landing kinetics and fatigue. PURPOSE: To gain a better understanding of asymmetrical kinetics during multiple drop landings as fatigue increases. METHODS: 13 recreationally active adult volunteers, 7 females and 6 males, were recruited to participate in the study. Demographically the participants were between the ages of 18-39 years old. Each volunteer participated in two sessions, an informative session to discuss what he/she would be preforming and a session of drop landings (pre-fatigue and fatigue). Participants performed 5 non-fatigued drop landings, condition 1, from a 60cm tall box. After pre-fatigued data were collected, participants warmed up and went directly into the fatigue protocol. The fatigue protocol consisted of a 20 second Wingate test followed by 5-drop landings starting within 30 seconds of the Wingate test. The subject then had an active 5-minute recovery starting at the end of the 20-second Wingate test. This fatigue protocol was completed four times, conditions 2-4, by each participant in a continuous fashion. Participants were barefoot throughout the fatigue and landing protocol in order to give a consistent landing surface between subjects. Data were analyzed with a repeated measures ANOVA. RESULTS: There was a significant main effect found when comparing the Max Vertical Ground Reaction Force (MVGRF) for participants dominant and non-dominant legs following 5 landing conditions (p=0.001). Pairwise contrasts were performed post hoc, which revealed significant differences between baseline and condition 2,3 and 4 (p=0.001, p=0.010, and p=0.006). There was no significant difference between baseline and condition 5 with p=0.126. There was also no significant main affect found for leg dominance with p=0.089. Despite this there was an interesting event during the 3rd condition where there was a significant difference between dominant and non-dominant legs (p=0.002). Lastly there was no significant main affect when comparing initial contact time to MVGRF and leg dominance (p=0.096). CONCLUSION: Within the scope and limitations of this study we found that fatigue may have a direct effect on MVGRF of drop landings. Also, there was an interaction between fatigue and asymmetry in dominant and non-dominant legs, however further inquiry must be made in order to understand this relationship.

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