~it's because you do exercises so vigorous or quickly, your inhaled oxygen can not
oxidize enough the monosacharide ,like glucose, to release energy for you need( aerobic respiration )
~but your body need energy to 跳break dance, 倒立同freeze, so it must use anaerobic respiration (無氧呼吸), this process will produce some by-product(副產品),
it's 乳酸, they will accumulate in your muslce. And make your muslce pain OR無力
~you can massage the muslce or sock in the hot water those can release 乳酸