Couldn’t agree more. There is a better way!
Read the literature as you did. Make a guess. Aim on the slightly high end for sodium replacement. Be quantified in your approach, but listen to and observe your body’s own feedback. No training interruption needed. Far more time efficient, as you noted!
For those reading:
If drinking lots, peeing lots, and losing weight → intake more sodium.
If drinking lots, not peeing, and losing weight → intake more fluid and more sodium in direct proportion to more fluid.
If peeing lots and maintaining weight → drink less fluid and take more sodium.
If not peeing and maintaining weight → probably in the ballpark, but maybe more fluid is better, if activity duration is >4 hrs. Need to urinate is sign of good hydration and necessary in long activities.
If HR drifts up for power and not peeing → more fluid.
If HR drifts up for power and peeing lots → more sodium.
If HR does not drift up for power and peeing lots → less fluid.
If HR does not drift up for power and not peeing → you’re probably in the ballpark.
If thirsty and peeing lots → intake more sodium and less fluid.
If thirsty and peeing little → more fluid and more sodium.
If not thirsty and peeing lots → more sodium.
If not thirsty and peeing little → might be in the ballpark but might also be way low sodium and need a bit more to drive thirst up. Check HR drift. If drifting, more sodium and more fluid.
If cramping → consider increased sodium and maybe increased fluid but if increasing fluid, increase sodium by more.
If GI distress → consider increased fluid, or lower total consumption of carbs & sodium, or better gluc:fruc ratio.
Usually the result of sweat testing is:
- Overconfidence in inaccurate sodium intake needs.
- Ignoring what the body is already telling us. (urination, body weight loss, thirst, cramping, fatigue, cardiac drift, etc, all tell us more than enough to make very good guesses about what needs to happen)
- High time cost.
- Confirmation of what the literature tends to tell us.
- Forgetting that sweat sodium concentrations and sweat rates change dramatically with changing conditions, fitness, training experience, body weight changes, clothing choice, absolute intensity, relative intensity, etc. Ignoring those things leads to rigidly following a plan that was designed for different conditions.
In your case, you tested often enough to notice that “stuff changes” and “results are variable.” Good on you!
Yep. Salt tablets have a ridiculously low amount of sodium in them. Most folks should intake 500-1500mg per hour. If sweating heavily, definitely target the top end. Don’t exceed 1500mg per liter of water…mayyyybe 1800mg/L. Depending on the salt tab, you’d have to take a salt tab every 10-15 minutes for the entire duration of the activity, LOL. Maybe twice as often, in the case of some ridiculous products.