Body weight before and after bike

there are at least two schools of thought on this.

a) the first is to drink to thirst. Drink when your body tells you to. It knows best
b) the second is drink to a schedule. Determine how much your body loses, how much you need to replace for optimal performance and execute. this can be oz/min, bottles per hour....

people that believe in b do the test your talking about. Weigh yourself before, do excercise, compensate for what you drink and pee, weight yourself after, figure out a sweat rate, figure out a maximal body loss they want to achieve (say 2%) and then calculate a schedule that probably includes electrolyte replacement. People in this camp will say that more than 2% body weight loss is sub optimal for performance....need x mg of sodium per L to prevent hyponetremia....bla bla bla

BTW hyponetremia is an imbalance of sodium in the body. Some say it's caused by not taking enough sodium, other say it's caused by drinking too much....

To add complexity to all this, some very renowned scientists say women are different than men, and women in their cycle are different than women not in their cycle.

If I understand correctly, one symptom of a person potentially become hyponatremic is not losing weight will exercising while ingesting fluids. I AM NOT SAYING THAT IS HAPPENING TO YOU. I think your test is probably too short and there may be wonky things going on.

The reason I wrote this is because you should research this especially as you go longer, and if you are racing in warm weather.

I would listen to this

http://www.enduranceplanet.com/dr-tim-noakes-and-dr-phil-maffetone-...


Tim Noakes is definitely a guy who's data I would consider in my decision.

In addition to what Marc posted about hydration, electrolytes, etc, you also need to consider that your scale has a margin of error - let's assume 1%; then we have:

Pre-ride - 72.1kg +/- .7kg
Post-ride - 73.6 =/- .7kg

Therefore your pre-ride mass may have been as great as 72.8kg and your post-ride may have been as low as 72.9kg. Factor in taking on 1.2kg of water plus .15kg of fuel and you could be in the situation that you pretty much replenished what you lost.

Now, there is the possibility that you were as low as 71.4kg before the ride and as high as 74.3kg post ride but, assuming you correctly accounted for what you took in, this is impossible.

Really the key point is that your error bars certainly would account for the delta that you see which means you need more data if you want to try to figure this out.

Shane

and 1% would be a very accurate scale, Most scales are not that good.

Indeed - I meant to mention that it is most likely off by quite a bit more than 1%.

Shane