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REPLACEMENT vs REPLENISHMENT

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BY STEVE BORN AND NEIL VALLANCE

What is best??? Replace what you lose? Or what you can assimilate? (Hint: Less in better than more!)

Perhaps the biggest challenge we at Hammer Nutrition face is convincing athletes that the “replace what you lose” theory of endurance fueling is completely ineffective and one that needs to be eliminated if better results are to be achieved.

What we’re talking about are the “experts” and organizations recommending that athletes need to consume what they lose during exercise in equal to near-equal amounts. They drum up statistics such as “you lose up to two grams of sodium per hour, burn up to 900 calories hourly and sweat up to two litres an hour” to defend their position.

When looking at calories burned in a high intensity workout, you would need to consume 7-9 Gels an hour to replace all those calories. A moderate workout where you would burn 200-300 calories an hour would require 2-3 Gels, PER HOUR, to achieve replacement!!! Even worse is that, in many instances, they don’t give any numeric guidelines, just vague statements like “drink as much as you can”. Sadly, far too many athletes fuel their bodies exactly this way - based on the recommendations of what one elite athlete may be using and/or saying - with only poorer-than-expected results or a DNF to show for their efforts.

What these “experts” don’t take into account when making these “replace what you lose” recommendations is that how much you’re losing - fluids, calories, and sodium - is totally secondary to what you can effectively replace. In other words, what you are burning/losing is not what you should be focusing on, but rather what the body can reasonably assimilate (think digest and absorb) during any given period of time. Two points that represent our position on what proper fueling is all about are:
  1. To suggest that fluids, sodium and fuel-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. IE, YOU CANNOT REPLACE EVERYTHING THAT YOU BURN DURING EXERCISE! 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.
  2. 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.
What this means is that the body cannot be replenished at the same rate that it becomes depleted. Yes, the body needs your assistance in replenishing what it loses but that donation must be in amounts that cooperate with normal body mechanisms, not in amounts that override these crucial mechanisms.

Here’s an important fact to keep in mind - At an easy aerobic pace, the rate of metabolism increases from a sedentary state to a range of 1200-2000%.  As a result, the body goes into “survival mode” where blood volume is routed to working muscles, fluids are used for evaporative cooling mechanisms and oxygen is routed to the brain, heart and other internal organisms. Interestingly, it is NOT focused on calorie, fluid, and electrolyte replacement, as some of the “experts” advise. In other words, the body already “knows” it is unable to immediately replenish calories, fluids and electrolytes at the same rate it uses/loses them and it deals with this issue by releasing specific hormones that compensate for all but about 20-30%, which can be replenished orally.

That’s why we don’t recommend trying to replace hourly losses of calories, fluids and electrolytes with equal amounts, but instead recommend a smaller replenishment donation, one that cooperates with normal body mechanisms.

Some common fuel-related characteristics of poorer than expected performance are:
  • Fluid intake is nearly always over 880ml/hour.
  • Body weight at finish is hyper-hydrated with weight gain above 1-2%.
  • Body weight at finish is dehydrated with weight loss over 3%.  NOTE: Weight loss or gain of over 2% leads to hyponatremia problems.
  • Excess calorie consumption, especially from simple sugar fuels, which raise osmolality in the gut, forcing the body to pull electrolytes out of an already electrolyte-depleted system, causing stomach shut down.
  • Excess sodium from diet and/or during exercise intake. NOTE: Not only are high sodium diets bad for your health, but those who consume high amounts of sodium in the diet are guaranteed greater sodium loss rates and require greater sodium intake during exercise. Sodium, as you know, drives thirst and thirst drives drinking until excess results... not a good scenario.
Our Basic Recommendations:
  • Fluids – 470-830ml hourly
  • Sodium Chloride - 300-600 mg hourly 
  • Calories – 120-180 calories hourly
There are many individual variations that you will need to consider (age, weight, training/racing stress, fitness, acclimatization levels, weather conditions) to determine what works best for you. However, these are the amounts - the “gauges” if you will - that are a good starting point for you, amounts we feel will serve you the best in your workouts and races.

The bottom line is that if you hope to achieve better results in your workouts and races and if you want to greatly decrease the opportunity for a whole host of maladies from occurring, you need to ditch the “replace what you lose” concept and adopt the “fuel in cooperation with your body” concept.