4521
Replacing What You Lose or What You Can Assimilate
This is a suggested comparison showing "approximated" upper values for what is lost during prolonged endurance exercise to what can be successfully absorbed, replaced, routed into the energy cycle for the bulk of the fit, acclimatized endurance athletes. This material was extracted from the following literature:
1-Noakes T.D. Lore of Running. Leisure Press. Champaign Illinois. Pages 768-770 29 published and unpublished papers cited on fuels, fluids, electrolyte issues during endurance exercise. (This is cited due to the length that 29 references would take in this reply.)
2-Moodley D. et al., Exogenous carbohydrate oxidation during prolonged exercise. The effect of carbohydrate type and solution concentration. Unpublished manuscript in #1 above.
3-Sweat Composition in Exercise and Heat. Verde T, Shephard RJ, Corey P, Moore R, 1982 J Appl Phys 53(6) 1541-1542.
4-Sweating: Its composition and effects on body fluids. Costill DL, 1977 & 1982., Annals of the New York Academy of Sciences, 301, p.162.
5-American Dietetics Association Position Statement
6-Amercian College of Sports Medicine Position Statement
The approximate values are estimated for fit acclimatized subjects:
Both fluid volume and sodium are controlled to a degree by pathways between the human brain and internal organs precisely monitored and moderated by kidney and hormone signals initiated from the brain causing re-circulation when levels are detected low. This accounts for variation and range differences between individual athletes. Calorie oxidation rate and gastric absorption rate typically allow for no more than 300 calories per hour to be consumed by an athlete with successful energy transfer with positive quality and quantity gastric absorption results. Adding over this amount typically induces indigested calories in the gut, which contribute to no calories crossing intestinal linings without osmolar solute assistance from the gastrointestinal tract or oral dose correction.
The human body has so many survival safeguards by which it regulates living one more minute, that when we try too hard to fulfill all its needs we interfere doing more harm than good. If I replace 100% fuels lost at 700-900 calories per hour, I bloat, vomit, present diarrhea, and finish the event walking or DNF at an aid station. If I replace all the fluids lost all at once, I end up in the emergency tent with an IV for dilutional hyponatremia. If I replace all the sodium my body loses at the rate of 2 g/hour, I end up with swollen hands, eyes, ankles, feet, and noticeably labored exercise, or hypernatremia-induced bonking.
Based on position papers from ADA and ACSM, sweat composition studies by Shephard, Noakes, Costill, et al., the following replacement values we have observed for the majority of fit acclimatized endurance athletes (+/-5%):
We have been publishing this for a number of years. For many athletes cramping, vomiting, gastric distress, diarrhea, and systemic malaise result when the attempt to replace all the fluids, fuels, and electrolyte (especially sodium) at the rate they were lost. Some who listen to our plea to use less, when they correct intakes to lower absorption property levels, their specific problem ends and performance improves dramatically. However, there are people who can complete events on high intake of fluid, fuel, and electrolyte, but unfortunately the majority cannot or they would do better with less.
It is curious to me that one elite athlete whose huge intake of this or that fuel, fluid, or electrolyte should publish or recommend that dose for millions others whose basal state metabolism cannot possibly absorb and return to the energy cycle at an unproven rate. There are few exceptions to these reported reference ranges.
1-Noakes T.D. Lore of Running. Leisure Press. Champaign Illinois. Pages 768-770 29 published and unpublished papers cited on fuels, fluids, electrolyte issues during endurance exercise. (This is cited due to the length that 29 references would take in this reply.)
2-Moodley D. et al., Exogenous carbohydrate oxidation during prolonged exercise. The effect of carbohydrate type and solution concentration. Unpublished manuscript in #1 above.
3-Sweat Composition in Exercise and Heat. Verde T, Shephard RJ, Corey P, Moore R, 1982 J Appl Phys 53(6) 1541-1542.
4-Sweating: Its composition and effects on body fluids. Costill DL, 1977 & 1982., Annals of the New York Academy of Sciences, 301, p.162.
5-American Dietetics Association Position Statement
6-Amercian College of Sports Medicine Position Statement
The approximate values are estimated for fit acclimatized subjects:
| SUBSTANCE | RATE LOSS | P.O. (Gastric Emptying Rate) |
| Fluids | 1-3 liters | 17-28 fluid ounces |
| Sodium | 2000 mg/hr | 500-700 mg/hour |
| Fuel (Carb Cal) | 700-900 Cal/hr | 240-280 Cal/hour |
Both fluid volume and sodium are controlled to a degree by pathways between the human brain and internal organs precisely monitored and moderated by kidney and hormone signals initiated from the brain causing re-circulation when levels are detected low. This accounts for variation and range differences between individual athletes. Calorie oxidation rate and gastric absorption rate typically allow for no more than 300 calories per hour to be consumed by an athlete with successful energy transfer with positive quality and quantity gastric absorption results. Adding over this amount typically induces indigested calories in the gut, which contribute to no calories crossing intestinal linings without osmolar solute assistance from the gastrointestinal tract or oral dose correction.
The human body has so many survival safeguards by which it regulates living one more minute, that when we try too hard to fulfill all its needs we interfere doing more harm than good. If I replace 100% fuels lost at 700-900 calories per hour, I bloat, vomit, present diarrhea, and finish the event walking or DNF at an aid station. If I replace all the fluids lost all at once, I end up in the emergency tent with an IV for dilutional hyponatremia. If I replace all the sodium my body loses at the rate of 2 g/hour, I end up with swollen hands, eyes, ankles, feet, and noticeably labored exercise, or hypernatremia-induced bonking.
Based on position papers from ADA and ACSM, sweat composition studies by Shephard, Noakes, Costill, et al., the following replacement values we have observed for the majority of fit acclimatized endurance athletes (+/-5%):
| UNIT | REPLACED % |
| FUEL | 30-40% |
| FLUID | 20-33% |
| SODIUM | 20-35% |
We have been publishing this for a number of years. For many athletes cramping, vomiting, gastric distress, diarrhea, and systemic malaise result when the attempt to replace all the fluids, fuels, and electrolyte (especially sodium) at the rate they were lost. Some who listen to our plea to use less, when they correct intakes to lower absorption property levels, their specific problem ends and performance improves dramatically. However, there are people who can complete events on high intake of fluid, fuel, and electrolyte, but unfortunately the majority cannot or they would do better with less.
It is curious to me that one elite athlete whose huge intake of this or that fuel, fluid, or electrolyte should publish or recommend that dose for millions others whose basal state metabolism cannot possibly absorb and return to the energy cycle at an unproven rate. There are few exceptions to these reported reference ranges.
