Completar frases Activate B1+ Unit 6Versión en línea Modal Verbs por Guadalupe Soto Reyes 1 need don't musntn't can should must can mustn't have should had Sports trainer Jenny Bolton answers your questions . Tony : I've been going running every day for nine days , but my legs don't hurt at all . Do I really to have a rest ? Jenny : You wait until your legs hurt to have a rest day - that's asking for an injury . No matter how you feel you absolutely rest once a week . Of course you don't to sit at home all day ! You go for a short walk to stretch your legs , but nothing too energetic . And ideally you have a leg massage once a month . Jason : Is it OK to go running in baseball boots ? They're much cheaper than proper running shoes . Jenny : You wear baseball boots or other soft shoes for running as this lead to serious injury . A friend of mine who had been running with baseball boots to have a knee operation last year . You have to buy an expensive pair , but you do have to ensure that they offer proper protection for your heels and your ankles . Maybe you think about buying some new shoes in the sales .