“内练一口气，外练筋骨皮”是习武之人一定要做的事情。“内练一口气”说的是将丹田一口气运用自如，以至打通各关，贯穿全身，可强身健体，抵御外敌，实乃习武之第一大要素，重要之程度远高于习十八般武艺的‘外练筋骨皮”。不练“一口气”，只练“筋骨皮”，则被称为脚下无 “Breathing in one breath, practicing bones skin” is a martial arts must do things. “Breath of one breath” is to use the pubic region breathlessly, and even get through all the customs, throughout the body, can keep fit, resist foreign enemies, it is actually the first element of martial arts, the degree of importance is much higher than Xi Eight martial arts ’outer exercise gluten skin.’ Do not practice ’breath’, only practicing ’bones skin’, is called the foot without