Medicine & Science in Sports & Exercise:
B-16 Thematic Poster - Neuromuscular Retraining: JUNE 1, 2011 1:00 PM - 3:00 PM: ROOM: 304
University Medical Center Groningen, Groningen, Netherlands. (Sponsor: Donald T. Kirkendall, PhD., FACSM)
(No relationships reported)
Injury surveillance shows that ACL injury rates have not diminished. While explicit learning strategies are used for prevention, this may be unsuitable for modifying complex motor skills.
PURPOSE: We compared explicit vs. implicit learning related to improving balance, a key element in ACL injury prevention programs.
METHODS: 60 healthy and physically active subjects (18 to 24 years; 36 females, 24 males) were randomly and equally distributed over 3 groups. Subjects balanced on a ridge 40mm high and 4mm wide using their preferred foot until the opposite foot touched the floor. There was no maximum time. Subjects wore athletic shoes and had 1-minute rest between trials. Each trial was recorded with a digital video camera linked to a laptop. Balance time was measured using Windows Movie Maker. During the intervention (G1), each group received different feedback: implicit (video feedback of their best trial), explicit (verbal feedback) or no feedback (control). A retention test with no feedback was conducted two weeks later (G2). Each session consisted of 25 trials. The main outcome measure was improvement of balance time within each session. Individual linear regressions were calculated and the slope (improvement) for each subject's line was statistically analyzed using a 3×2×2 repeated measures ANOVA. The a priori alpha level was set at p<0.05.
RESULTS: G1 slopes for implicit, explicit and controls were 2.36 ±3.2 (p=0.009), 1.53 ±2.1 (p=0.001) and 0.84 ±1.3 (p=0.209) respectively. The slope of the implicit group was significantly greater than control (p=0.044). The initial G2 trials were similar to their final G1 trials. None of the groups had a significant slope in G2, neither were they significantly different from each other. Balance time for both intervention groups improved from G1 to G2 (p=0.007 and p=0.041 respectively). Follow-up tests showed significant increases in balance time from G1 to G2 for males in the control group (p=0.006), females and males in the explicit group (p=0.035 and p=0.013 respectively) and females in the implicit group (p=0.020).
CONCLUSIONS: G1 slope for the implicit group was significantly different from the control group. Gender differences were seen in the control and implicit groups. Regardless of approach (implicit or explicit) constant feedback is needed to improve balance.