The "3 hour rule":

During sport, your muscles use a huge share of your blood, taking it away from your stomach and intestines: this is why the well-known "3 hours rule" that tells us to leave three hours between our last meal and starting sport, should be followed. 3 hours is the minimum time after which you can start sport knowing that you have finished digesting and thus limiting the risks of digestive problems or premature muscle fatigue.

Also, different factors such as repeated shocks with the ground as you run, or dehydration, can increase the risk of digestive problems: so you should steer clear of too many solid foods.

Everyone has their own individual tolerances, and you should take this into account.

Water is an athlete's primary need, but why do we need to drink?:

The human body is made up of 60% water. During physical effort, around 75% of the energy your body produces is dissipated as heat. To regulate body temperature, your body needs to eliminate the excess heat through perspiration, which leads to significant loss of water and minerals (1.5 to 2 litres per hour when running in temperatures of 25°C). Several factors affect how much we perspire during sport (athlete's personal factors, outside temperature and relative humidity, nature, intensity and duration of the exercise, altitude, clothing, wind levels, etc.).

So any dehydration, however mild, alters our physical abilities considerably: for example, dehydration equivalent to 1% of body weight leads to a 10% drop in physical capacity, and also increased risk of long-term muscle and tendon problems.

So you should always ensure you make up for water loss right from the start of your exercise, before you feel thirsty, because by then it is too late.

"Why do energy drinks hydrate us faster than just water?" Energy drinks contain carbohydrates to ensure constant provision of energy, and also vitamins and minerals to compensate for loss through sweating. The presence of both glucose and sodium ensures that the drink is absorbed faster than just water, helping re-hydration.

Adapted drinks:

Some drinks, called hypertonic* , are not suitable for sports use. Because they contain too high a concentration of glucose and/or sodium, they may bring on digestive discomfort during sport, especially in hot weather (stomach cramps and burning feeling, colic). Prefer hypotonic drinks, or diluted isotonic solutions, which will significantly reduce the risk of stomach pains.

Informative table giving recommended concentrations of glucose depending on outside temperature

Outside temperature	< 10 °C	10 – 25 °C	> 25 °C
Glucose concentration	80 g/l	60 g/l	30-40 g/l

 

This table only applies for drinks that contain only glucose. Carbohydrates such as maltodextrin (or glucose polymers) can increase the glucose concentration of a solution without necessarily bringing on stomach pain or giving the drink too much of a sugary taste. Varying the concentration aims to provide the same quantity of glucose, whatever the outside temperature. In hot weather, the priority is to compensate for water loss, and so the total volume drunk is higher. So it's a good idea to dilute your drink. Conversely, in cold weather, water loss is lower but energy needs are greater. This is why it's best to use concentrated drinks to get lots of energy with a low volume, providing this doesn't cause any digestive pain.

Your stomach, weakened during sport, is particularly sensitive to acidic solutions. If you suffer from indigestion, burning or acid reflux, choose an energy drink with a neutral pH, which will ensure optimum digestive comfort.

Because it slows down the emptying of the stomach, drinking too much fluid can cause bloating and abdominal pain. But drinking small quantities of isotonic energy drinks regularly can reduce the risks of stomach pain and help the body to assimilate carbohydrates.

Depending on effort:

- Exercise less than 1 hour:
• Drink regularly, from the start of exercise and throughout. Plain water is sufficient.
• Ideally, you would drink 2 to 3 mouthfuls every 15 minutes (at least 500ml per hour). Temperature at 10 to 15°C is ideal, in theory. However, in practice, this temperature is often difficult to maintain throughout exercise. You should avoid drinks that are too chilled because they can speed up your digestive transit during exercise.

- Exercise for 1.5 to 2 hours:
• Prefer an isotonic energy drink that is suitable diluted (or 1 to 2 energy gel packs** per hour, with water). Ideally, you would drink 2 to 3 mouthfuls every 15 to 20 minutes (at least 500ml per hour),
• Solids are not necessary but some "instant energy" products can also be useful depending on the intensity of your exercise and/or when extra effort is required (at the end of the race, for example) when your batteries are running low.

- Exercise for 2 to 2.5 hours:
• Prefer a maltodextrin-based drink (or 1 to 2 "endurance" gel packs per hour, taken with water). Ideally, you would drink 2 to 3 mouthfuls every 15 to 20 minutes (at least 500ml per hour).
• Depending on how you're feeling, you can also take small quantities of solids every 30 to 45 minutes: cereal bar, gingercake, dried fruits, piece of energy cake, fruit jelly, etc.

Why do you sometimes feel digestive discomfort during sport?:

Several athletes suffer from digestive discomfort during sport (bloating, abdominal pain, acid reflux, nausea, transit problems, etc.). But a few, simple-to-follow dietary rules will help you optimise your digestive comfort during sport. If you suffer from persistent discomfort, seek advice from your doctor or consult a dietician*** .

Aptonia has developed specific energy products such as the "Hydra" range to satisfy your energy needs and provide the different nutrients your body needs.

Your nutritional coach.

Stéphane D.

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*Hypertonic: refers to the osmolarity -> the quantity of active particles, including glucose and sodium, present in a solution. A solution can be called "isotonic" when in contains as many particles as plasma. However, a "hypertonic" solution contains more molecules than plasma, and a "hypotonic" solution contains fewer.
**Energy gel or honey packs are very practical because they are compact and rich in refined sugar. There is no need to consume more than 1 or 2 gel packs per hour. Also, for the same tonicity reasons as energy drinks, you must drink plenty of plain water to better absorb these sugars (equivalent to a cup of water at the same time as the gel, then again 10 to 15 minutes later).
***www.dietitiansunlimited.co.uk.