the solution: make sure that you don't lunge forward with your feet. this is especially important when running downhill.
解决方案:注意,您伸脚别太靠前,这一点在下坡时尤其重要。
「one day we saw an adolescent orang-utan called sif wade into deep water, hunker down and then lunge forward making simple paddling movements with her arms and legs,」 says russon.