A question has arisen on a professional nutrition email discussion list about the relative efficiency of energy use during running compared to walking.
By way of background, the data in Ainsworth et al (1999) and Ainsworth et al (2000) indicate that: Walking at 2 mph (3.2 kph) has a MET equivalent of 2.5. For 3 mph (4.8 kph) , the MET equivalent is 3.5. For 3.5 mph (5.6 kph), the MET equivalent is 4.0. For 5 mph (8 kph), the MET equivalent is 8.0. If you graph these, the curve for rate of energy expenditure against speed is approximately linear at least up to 5.6 kph. Somewhere between 5.6 kph and 8 kph there appears to be an inflection point and energy expenditure then increases at a greater rate than speed. Also from the references cited, walking at 8 kph involves the same energy cost as running at 8 kph (8 METs in each case). Is it reasonable to assume that below ~8 kph walking is more energy efficient than running for most people, while above ~8 kph running is generally the more economical gait? If so, does this also apply to competitive walkers, or does their technique mean that the 'crossover point' (at which running economy is greater than walking economy) occurs at a higher speed? References Ainsworth BE et al (1993). Compendium of Physical Activities: classification of energy costs of human physical activities. Med. Sci. Sports Exerc. 25(1): 71-80. Ainsworth BE et al (2000). Compendium of Physical Activities: an update of activity codes and MET intensities. Med. Sci. Sports Exerc. 32(9): S498-S516. Chris Forbes-Ewan Defence Scientist (Nutrition) S&T5 Defence Nutrition DSTO-Scottsdale PO Box 147 SCOTTSDALE Tas 7260 AUSTRALIA Phone: Int + 61 3 6352 6607 (03 6352 6607 within Australia) Fax: Int + 61 3 6352 3044 (03 6352 3044 within Australia) The opinions expressed in this message are those of the author, and should not be taken to represent the position of the Defence Science and Technology Organisation or of the Australian Department of Defence. IMPORTANT: This email message remains the property of the Australian Defence Organisation and is subject to the jurisdiction of section 70 of the CRIMES ACT 1914. If you have received this email message in error, you are requested to contact the author and delete the message. ------------------------ Yahoo! Groups Sponsor --------------------~--> Help save the life of a child. Support St. Jude Children's Research Hospital's 'Thanks & Giving.' http://us.click.yahoo.com/6iY7fA/5WnJAA/Y3ZIAA/2_TolB/TM --------------------------------------------------------------------~-> Post messages to [EMAIL PROTECTED] To (un)subscribe, send any message to sportscience-(un)[EMAIL PROTECTED] View all messages at http://groups.yahoo.com/group/sportscience/. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/sportscience/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
