2. Muscle building or strength exercises

These are strenuous _ex_e_r_c-is_e_s_a-im_e_d_a_t_1_·n-c-re_a_s-in-g-~ 66 This process is called aerobic metabolism. 67 Smolin & Grosvenor, 1994. 68 McManners, 2004. the bulk and/or tone of the muscles. Muscle-building or weightbearing exercise firms up the body, improves stamina and pumps calcium into the bones, which aids in maintaining their density and strength. Ibn al-Qayyim observed in Medicine of the Prophet that the regular involvement of different organs in a suitable type of physical activity strengthens them. 69 Strength exercises are also called anaerobic exercises, as the heart in this case cannot pump oxygen fast enough to support the energy needs for these intense training sessions, so the body has to rely solely on the breakdown of carbohydrates. Under anaerobic conditions, the carbohydrates are still not fully broken down; this yields lactic acid as an end product, which causes cramps and fatigue when it accumulates in the muscles. That is why after high intensity muscle training, it is useful to have a mild cool-down like a gentle walk, stretches or easy movements to allow enough blood flow to the muscles. This will deliver oxygen to remove the built-up acid, thus relieving the cramps. 70 Anaerobic exercises include running, jumping, high intensity gymnastics, weight-lifting or any activities involving high levels of effort sustained over a short period of time. Women especially are advised to perform some type of anaerobic or strength exercise at least once a week to help reduce the risk of osteoporosis 71 and other post-menopausal symptoms.