Running intralimb coordination patterns after a foot core exercise program in recreational runners

Abstract

This study investigated the effects of a foot core intervention on the coordination of foot joints in recreational runners. This was a secondary analysis from a randomized controlled trial conducted with 87 recreational runners allocated to the control group (CG), which followed a placebo lower limb stretching protocol, or the intervention group (IG), which underwent an 8-week (3 times/week) foot core training. The participants ran on a force-instrumented treadmill at a self-selected speed (9.5-10.5 km/h) while the foot segment motion was captured. The vector coding technique was used to assess inter-joint coordination for four selected coupled segment and joint angles. The coordination patterns of the calcaneus and midfoot (CalMid) and midfoot and metatarsus (MidMet) joint pairs were affected. In the frontal plane, IG showed an in-phase with proximal dominancy coordination at heel strike, with a decrease in its frequency after the training (P=0.018), suggesting a longer foot supination. Additionally, IG showed an anti-phase with distal dominancy pattern at early stance compared to CG due to a smaller but earlier inversion of the CalMid-MidMet pair (P=0.020). The intervention also had an effect on the transverse plane of the CalMid-MidMet pair, with IG showing a significantly greater frequency of anti-phase coordination with proximal dominancy during propulsion than CG (P=0.013), probably due to a reduction in the CalMid abduction. Overall, the results suggested that the foot core intervention reduces the occurrence of running-related injuries by increasing the resistance to calcaneus pronation and building a more rigid and efficient lever during push-off.

Figure 1. CalMid-MidMet angular displacement diagram (left axis) and frequency of coordination patterns (right axis) in the frontal plane for the control group (CG) and intervention group (IG). The green and red solid lines represent angular displacement of the CalMid joint in the CG and IG, respectively. The green and red dashed lines represent angular displacement of the MidMet joint in the CG and IG, respectively. The green and red dots represent the coupling angle for the CG and IG, respectively. The green and red bar chart represents the average frequency percentage within each group (CG and IG, respectively) of the coupling angle during the gait cycle within each coordination pattern, shown as horizontal white and gray segments. CalMid: calcaneus and midfoot; MidMet: midfoot and metatarsus.

Figure 2. CalMid-MidMet angular displacement diagram (left axis) and frequency of coordination patterns (right axis) in the transverse plane in the control group (CG) and intervention group (IG). The green and red solid lines represent angular displacement of the CalMid joint in the CG and IG, respectively. The green and red dashed lines represent angular displacement of the MidMet joint in the CG and IG, respectively. The green and red dots represent the coupling angle for the CG and IG, respectively. The green and red bar chart represents the average frequency percentage of the coupling angle within each group (CG and IG, respectively) during the gait cycle within each coordination pattern, shown as horizontal white and gray segments. CalMid: calcaneus and midfoot; MidMet: midfoot and metatarsus.