¿por qué es importante donar sangre? ¿qué hace que la sangre en el cuerpo? ¿por qué necesitamos sangre? ¿cómo protege la sangre el cuerpo? ¿por qué tenemos diferentes tipos de sangre?

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.