The quadricepsmuscle brings your knee into full extension.
四头肌肌肉让你的膝进入完全的延长。
2
Without lifting your heel up in the air, tighten your quadricepsmuscle as hard as you can for ten seconds.
向上举起你的脚后跟，绷紧你的四头肌肌肉坚持10秒。
3
It doesn't mean you can't climb mountain but first you need to strengthen up the quadricepsmuscle in terms of strength and muscular endurance so that your knee is stable when you are climbing.