Background: Maximum oxygen uptake (VO2max) is an important respiratory physiological index of the aerobic endurance of the body. especially for special groups such as drug addicts. and it is an important indicator for assessing the cardiopulmonary function and formulating exercise prescriptions. Although the cardiopulmonary exercise test (CPX) is a classic method to directly measure V... https://storeanimalwiz.shop/product-category/waterers/