Leijten, I. (Inge) (2012) Effect of instructions on reducing ground forces and knee valgus moment inrecreational athletes. thesis, Human Movement Sciences.
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Abstract
Abstract Non-contact ACL injury commonly occur during sports with an interval character, especially in football, soccer, handball and basketball. High knee valgus moment during landing or pivoting is known to be a biomechanical risk factor. Although it is still not well understood which factors increase the risk of an ACL injury, several prevention programs do exist. Often, these programs use traditional, explicit instructions; however, implicit instructions are expected to lead to longer lasting effects. In addition, the effect of implicit instructions could be more resistant under pressure or secondary tasks. This study was designed to determine which type of instruction could help in decreasing the vertical component of the ground reaction force (vGRF) and external knee valgus moment during a jump-landing task. Fifty subjects who performed an interval sport at least twice a week were included in this study. The subjects were assigned to either one of the implicit groups (auditory, analogy or visual), the explicit group or the control group. Subjects performed the jump-landing task thirty times during each of the three sessions. During the first session the subjects received instructions in accordance with the intervention groups, while during the retention sessions the subjects were only reminded to use the instructions. Results showed a significant direct learning effect for the visual group on vGRF (t(9)= -3.029, p=0.007), as well as a significant direct effect of the knee valgus moment for the explicit group (t(B)= -2.991, p=0.009). The other groups, except the analogy group, appeared to reduce vGRF or knee valgus moment to some extent. Furthermore, the explicit group (t(7)= -2.110, p=0.036) and control group (t(9)= -1.868, p=0.047) reduced vGRF after a week, whereas no effects were found in the knee valgus moment. After three months none of the instruction groups significantly reduced vGRF or knee valgus moment. Concluding, implicit, visual feedback is a powerful method to obtain rapid effects. However, explicit instructions appear to be a useful1nethod for direct effects as well. Since none of the groups revealed effects that last longer than a week it remains uncertain whether implicit instructions are more beneficial than explicit instructions in the long term.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Supervisor: and Otten, Prof. dr. E. and Benjaminse, Drs. A. and Institute: Human Movement Sciences and University of Groningen |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:49 |
| Last Modified: | 25 Jun 2020 10:49 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/1000 |
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