out to working muscles. The harder a run, the more oxygen muscles need, so the quicker the heart beats. This makes heart rate a useful measure of physical exertion, helping you avoid the most common training mistake of all - going too fast during long
Visit the official Runner's World page
Follow Runner's World on Twitter
Other Natmag-Rodale Sites
Run For Charity
About Runner's World
Runner's World is a publication of Hearst Magazines UK which is the trading name of The National Magazine Company Ltd, 72 Broadwick Street, London, W1F 9EP. Registered in England 112955. All rights reserved.
Website powered by: Immediate Media Company Limited. | © Runner's World 2002-2013 |