Walking is the oldest mode of transportation. After all， humans have been doing it for more than 1.5 million years. It’s also the cheapest， easiest form of aerobic exercise： all you have to do is open your front door， step outside and get moving.
Walking strengthens① the hips， quadriceps②， gluteus③ muscles and hamstrings. At speedier levels， when your heart rate is elevated， you can burn more calories than you might realize as well as improve your endurance. Research suggests that walking can reduce your risk of heart disease and may lower high blood pressure. In fact， a study indicates that walking two or more miles a day helped elderly men live longer. Since walking is a weight bearing activity， it also helps prevent osteoporosis④.
① strengthenvt. 加强；增强；巩固 vi. 变强大；变坚挺
② quadricepn. 复合腿部训练机
③ gluteusn. 【解】臀肌
④ osteoporosisn. 【医】骨质疏松
散步
徒步行走是最古老的交通方式，不论怎么说，人类已经行走了150万年。它还是一种最便宜，最简单的有氧运动，你所需要做的一切就是打开前门，走出户外，开始运动。
散步能锻炼臀部、四头肌、臀肌和腿筋。如果以较快速度行走，随着你心跳速率提高，你可以燃耗比你意识到还要多的热量，同时也增强了你的耐受力。研究表明，散步可以降低心脏病的发病率和降低血压。事实上，一项研究显示，一天步行2英里或更远可帮助老年人长寿。由于步行需要负重，它还可以帮助预防骨质疏松症。
