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November 7, 2018


The biggest debate about race nutrition and fuelling is how much and when! Hammer Nutrition believes there is a big difference between the energy you expend, and the amount of energy you can assimilate through your nutrition and fuelling.

“To suggest that fluids, sodium, and fuels-induced glycogen replenishment can happen at the same rate as it is spent during exercise is simply not true. Endurance exercise beyond 1-2 hours is a deficit spending entity, with proportionate return or replenishment always in arrears. The endurance exercise outcome is to postpone fatigue, not to replace all the fuel, fluids, and electrolytes lost during the event. It can’t be done, though many of us have tried.”

“The human body has so many survival safeguards by which it regulates living one more minute, that when we try too hard to fulfil all its needs we interfere, doing more harm than good.”


Assimilation will include ingesting, breakdown, digestion, and supply of nutrients to the various cells in the body. The table below gives a good display of the difference between expenditure and assimilation as well as the ideal replenishment rates of fluids, sodium and calories.

Loss vs. Assimilation

What can your body really handle?

Fluids (ml) 1000-3000 500-830
Sodium (mg) 2000 500-700
Calories 700-900 240-280(MAX)
Below are the corresponding replenishment values that we have observed for the average sized endurance athlete (72.5-75 kg) who is fit and acclimatized (+/-5%):
Fluids 20-33%  
Sodium 20-35%  
Fuels (Calories) 30-40%  


  • Noakes T.D., 2003, Lore of Running. Leisure Press. Champaign Illinois. Pages 768-770 29 published and unpublished papers cited on fuels, fluids, electrolyte issues during endurance exercise.
  • Moodley D. et al., 1992, Exogenous carbohydrate oxidation during prolonged exercise. The effect of carbohydrate type and solution concentration. Unpublished manuscript in #1 above.
  • Sweat Composition in Exercise and Heat. Verde T, Shephard RJ, Corey P, Moore R, 1982, J Appl Phys 53(6) 1541-1542.
  • Sweating: Its composition and effects on body fluids. Costill DL, 1977 & 1982, Annals of the New York Academy of Sciences, 301, p.162.
  • American Dietetics Association Position Statement
  • American College of Sports Medicine Position Statement

When fuelling lean, athletes are often concerned about running out of energy. A small (50kg) and lean (10% adipose tissue) athlete, will have 45000 calories stored as fat. Your body will use these energy reserves, and stored protein, to make up any difference in energy supply. Likewise, by fuelling leaner and avoiding simple sugars, you body will access and use these fat stores to keep you going during endurance exercise. 

With regards to Sodium and electrolyte replacement, the body has several balancing and supply mechanisms in place which can be overridden if oversupply occurs. The result can be in the form of cramps, or distinctly more serious consequences.

Linked to Sodium overdosing is excess water consumption. Hyponatremia is low sodium serum levels, and is primarily caused by consuming too much fluid during exercise.

It will always be easier to increase intake if an individual has been fuelling lean, as opposed to the opposite. Once too much is in, it is not coming out! (Well, at least not the way you would prefer!).

There is naturally athlete variability that is dependent on a variety of factors such as weight, fitness level, age, and weather conditions.

Here is Hammer’s recommendation to “Fuel Right, Feel Great”:
Calories per hour: 120-180 calories.
Fluids per hour: 600-750ml.
Electrolytes per hour: 1-2 Endurolytes Extreme, 1-2 FIZZ.