Hillclimb2003 Go to top | New Topic | Search     Subject: Muscular Efficiency Author: Peter Savage () Date:   2003-12-12 07:55:36.0 I started wondering about how efficient our muscles are (how many calories do we burn to do a certain amount of work) and what affects that efficiency. An average efficiency seems to be betwen 25% and 30%. If we assume MW is 1500 meters, and that rider + bike = 70 kg we have 105,000 kg m of work done. 1 kg meter = .002342 kCal. So we do about 245 calories of work (105 * 2.342). At 25 % efficiency that implies we burn about 980, at 30% 820, calories climbing the mountain. (This matches up with what I'd read about calorie consumption by elite cyclists of 17 to 18 per minute - 50 * 18 = 900). This (of course!) leads to a cadence discussion. I've found the following: http://www.slowtwitch.com/mainheadings/coachcorn/cadence.html http://www.competitionzone.com/articles/cycling-cadence.htm http://www.triathloncoach.com/pdf/life.pdf http://www.active.com/story.cfm?story_id=9601 http://www.bsn.com/Cycling/articles/cadence.html (with another thousand or so to read). I'm still trying to digest the articles, and some of the research was done at work rates too low to be of any real interest (100 watts). And some done with "untrained" subjects. The bottom line seems to be that at low rates of work the body is more efficient at lower cadences (60 or so being optimal) in terms of oxygen consumption. However, at higher rates of work (at lower cadences) it becomes necessary to start using fast twitch muscles (which are stronger) to develop the force necessary. (No motion in cycling is too fast for slow twitch fibres - bouncing at higher cadences is a function of neuro muscular coordination, not contraction rate failure). Fast twitch fibres burn glycogen much faster, build up lactate &c&c. Nor do they last long (endurance wise). Slow twitch muscles can use fat better. In many subjects 100 rpm was the cadence at which maximum "delta efficiency" was achieved - (the cadence at which a given increase in work required a minimum extra effort (as measured by ATP consumption etc)). It would seem that the optimal cadence, therefore, would be just above (sic) the level at which fast twitch fibres become necessary (lowering the cadence increases the force requirement, resulting, eventually, in fast twitch fibres being recruited). When I'm in to big a gear the "burn" starts, by changing down and spinning faster I can maintain the speed and the burn stops. Presumably the burn is due to the fast twitch fibres coming into use. It would also seem to suggest that riders with more strength can use a lower cadence without the problems attendant on fast twitch usage caused by too low a cadence. to be continued ... Go to top | New Topic | Search     Topics  Author  Date   Muscular Efficiency  Peter Savage    Dec-12-2003   RE: Muscular Efficiency  Palomino Filly    Dec-12-2003   RE: Muscular Efficiency  Rocky    Dec-12-2003   RE: Muscular Efficiency  Peter Savage    Dec-14-2003    Reply To This Message  Your Name:  Your Email:  Your IP Address: 38.107.191.110 Logged  Subject: Please type the above word into the box below: