From The RP Diet for Endurance: (the book I wrote and profit from)
Sweat Rates @ ~85 degrees during running.
There are tables for lower temps in the book too.
Electrolyte Content of Sweat
Not many useful studies on sweat rates during cycling so I didn’t attempt to form tables for that in the book.
Note: sweat rate and electrolyte content of sweat are affected by:
- Heat acclimatization
- Intensity of exercise
Makes it VERY hard to predict especially broadly for a population.
Weighing yourself pre- and post-training is by far and away the best way to gauge sweat rate. Hold your urine if possible. Weigh naked and dry both pre- and post-training.
Real talk…I’m a PhD in Sport Physiology, obsessed with performance, have a highly competitive cyclist/triathlete wife for whom I manage all training/racing/nutrition… we don’t weigh pre- & post-training. We don’t sweat test.
We do this:
- When not sweating noticeably, and it’s not anticipated that sweat production will be substantial: drink to thirst. Use 300-800mg sodium per liter.
- When sweating noticeably, we just assume that sweat rates will outpace maximum replacement rates. Therefore, we seek to max out fluid and sodium consumption as tolerated by gut. ~1-1.2L per hour, and 1000-1800mg sodium per liter.
Drink to thirst after training, and include at least half as much sodium per liter as you did during training.
With experience doing the above, you’ll start to learn how much you ought to carry.