Can Simple Postural Instructions Modify Running Forms in Recreational Runners

Abstract

Purpose/Hypothesis: Recent research suggests that alteration of trunk angle and foot strike pattern during running may result in beneficial changes that prevent running related injuries due to reduction in vertical ground reaction forces (vGRF). For example, running form emphasizing a forward trunk lean and a midfoot or forefoot strike pattern has been shown to be effective in reducing knee stress and the risks of other impact-related running injuries. In clinical practice however, it is currently unknown if simple postural cues given to runners can elicit motor learning that leads to modification of running form. The purpose of this study was to analyze the biomechanical changes in the running form of recreational runners after being instructed to run with a forward trunk lean and a forefoot strike pattern over a 4-week training period. Methods: Eighteen runners, 11 females and 7 males, mean age 28.5±6.10 years, mean body mass index= 23.18 kg/m2, that run at least five miles per week and are injury free at the time of the study participated. During a 4-week training period, the runners received the following simple postural instructions: 1) lean your trunk forward and 2) land on the front part of your foot. The runners were asked to focus on these postural cues whenever they ran on their own during the 5-week study period. Participants were assessed at the following time points: prior to training (PRE), immediately after receiving the instructions (iPST), at 2 weeks (2WK) and 4 weeks (4WK), and 7-10 days after the conclusion of training (RET). Assessment consisted of an initial running trial on a treadmill during which trunk angle and peak vertical ground reaction force (vGRF) in stance phase were assessed using a 3D motion capture system and a force plate-instrumented treadmill. The runners were assessed at their self-selected running speed and a predetermined speed of 2.5 m/s during which three 20-second trials were collected for each speed. One-way repeated measures ANOVA tests were used to compare the changes in trunk angle and peak vGRF over time. Results: There was a significant increase in forward trunk angle during running immediately after receiving the instructions for both running speeds (PRE vs. iPST, self-selected speed: 6.69o vs. 9.76o, p=0.001; 2.5m/s: 6.78o vs. 9.14o, p=0.005). When compared toPRE, there was a significant increase in trunk flexion angle at 4WK (PRE vs. 4WK, self-selected running speed: 6.69o vs. 9.94o, p=0.031; 2.5 m/s: 6.78o vs. 10.05o, p=0.002). When compared to PRE, there was a significant increase in trunk flexion angle at RET at 2.5 m/s speed (PRE vs. RET: 6.78o vs. 9.99o, p=0.044), however there was no significant increase in trunk flexion angle at RET for the self-selected speed (PRE vs. RET: 6.69o vs. 9.45o, p=0.111). There was no significant change in vGRF over the course of the training for the self-selected and 2.5 m/s speeds (p=0.644 and 0.187, respectively). Conclusions: Based on our findings, we conclude that simple postural instructions and training over 4 weeks can…