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Weigtloss and bike/run speeds.
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 2014-09-10 8:46 AM |
Veteran  820   Omaha, NE |  Subject: Weigtloss and bike/run speeds.So I was crawling around on another triathlon sight and I found a link to this article at the bottom. It states that a triathlete could gain 3s/mile per pound lost running, and 3s/ every 4 miles per pound lost for biking. These of course assuming no muscle is lost, or at least running/biking muscles. I guess the biggest one here is the biking time, it seems like a lot to me. I've heard of the 2s per mile for running before, but I didn't think weight mattered as much on the bike, unless going up hill, and defintely not down hill. Anyways I could stand to lose 30lbs. I'm around 6ft and 210 lbs. I did the bodpod a couple time and have been around 30-33% each time. According to this math I could cut. 30lbs x 3s x 26.2 miles = 39.3 minutes and for the bike 112/4 = 28x3x30 = 42 minutes. These times seem high to me, especially the bike. I ran numbers on a bike calculator, http://www.kreuzotter.de/english/espeed.htmand it says that for my speed (17.7) and weight (210) at IMAZ last year I did about 126 watts. Change my weight to 180, and speed goes up to 18.1, which would only cut about 9 minutes off my time. So which calculator would be more accurate. I know they won't be dead on, but at the same time, if I really could possibly save the higher amount of time, perhaps I would finally be convinced to lose the weight. Anyways here is the original article. http://kropelnicki.com/body-composition-metrics-sport-limiters/tria... |
| 2014-09-10 9:00 AM in reply to: cstoulil |
Member 1748  Exton, PA | Subject: RE: Weigtloss and bike/run speeds. By losing fat and not muscle you get faster, I don't think any calculator will be accurate for everyone on this. Remember that it's not just that you are moving less mass that makes you faster, If you are 30 lbs lighter you body no longer has to waste energy supplying that fat with oxygen. That oxygen now can go to your muscles; and on the bike you have less pressure against you abdomen which means you can breath easier. Chances are that if you work out enough to drop 30 lbs you will develop more power than you have now. Measure you power output now, loss 30 lbs and measure your power output again and report back to us if the calculators were accurate  |
| 2014-09-10 9:51 AM in reply to: cstoulil |
| 172 Kenmore, Washington | Subject: RE: Weigtloss and bike/run speeds. I agree, the bike formula is way off. It's closer to 1 second per mile per 10 lbs. The run number is about right. My personal experience has been closer to 4 seconds / lb of body weight, but that includes all the gains from run fitness. |
| 2014-09-10 1:40 PM in reply to: pnwdan |
| , Illinois | Subject: RE: Weigtloss and bike/run speeds. I think you need to take into consideration where you are starting from. If you weigh 110 lbs and lose a pound you could convince me it may make you faster. However if you start at 400 lbs and lose a pound I doubt it'll make any difference. I'm using extremes to make a point but I think it's a play on the Law of Diminishing Returns. Maybe to be more accurate this should be stated as a function of overall body weight percentage lost not the absolute number of pounds. |
| 2014-09-10 1:57 PM in reply to: ec1974 |
| 1055 | Subject: RE: Weigtloss and bike/run speeds. For running, I think 2 seconds per mile per pound is pretty universal. As far as biking. I'm not sold. If we're talking about going up hills, sure. If we're talking about enough weight that it alters your aerodynamic profile, then yes, I'll agree there too. But if I'm 10-15 lbs above race weight, its not going to matter on the bike the same way that it matters on the run. |
| 2014-09-10 9:56 PM in reply to: ziggie204 |
| , Illinois | Subject: RE: Weigtloss and bike/run speeds. This conversation is pretty pointless but I'll keep playing......optimum weight is optimum weight. If you're not there, get there. It's different for everyone. I race at about 170 pounds, cutting 80 pounds will not make me faster. There are way too many variables to say that cutting X pounds will make you Y seconds faster. You could probably make the argument that if you weighed 120 pounds you would gain speed by gaining weight (muscle). Also what about the added effect of gravity making you faster downhill the more you weigh? |
| 2014-09-10 10:28 PM in reply to: 0 |
| Subject: RE: Weigtloss and bike/run speeds. The statement about biking can't be 100% true because increases in speed are not linear to weight loss. As speed increases, the role of aerodynamics becomes a bigger factor. So even if you did find a situation where X pounds lost resulted in Y speed gain...you cannot take that example and thus infer that X*Z = Y*Z. If I were going to trust a bike calculator, it would be analyticcycling.com. The standard example (you need to zero out the slope) is a 75 kg rider at 250 watts. That results in 25.15 mph. Reduce the rider weight to 70 kg (11 pound difference) and the speed goes up to 25.21 mph. Or roughly a 7 second difference over 40k, or about 1 second per 4 miles per 11 pounds in this particular case. Again, you can't just assume 1 second per 4 miles, per 11 pounds all the time. It just works out that way for this scenario. Edited by Jason N 2014-09-10 10:30 PM |
| 2014-09-11 9:58 AM in reply to: Jason N |
Champion 6993 Chicago, Illinois | Subject: RE: Weigtloss and bike/run speeds. my gold std for running is .02 min/mile which gives you about 50 secs over the course of a marathon. That seemed pretty true as I go up and down weight. I done marathons from 250 lbs to 325 lbs. I will say this at 325 my marathon times are around 6:45 and at 250 It was around 5:30 so its pretty close to 1 min / lbs which was the first rule of thumb I heard. Remember though as you lose weight to have the gains you have to run faster and run more also. In my case I went from 4 miles in an hour to 5 miles in an hour but I still ran for an hour. When you lighter its easier and I try to remind myself that now as I fight to get back to my glory days that my time now is not as bad as I think because of the rule of thumb. Its a great motivational tool |
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