Unfit or just fatigued?

 

Air temperature

 

One of the main factors that influence fatigue is air temperature and how much a person sweats. Athletic performance is critically dependant on hydration not just because of its role in metabolism, but because water is the basis of our temperature control mechanism. When temperatures rise, the body will automatically start to sweat to cool it down, so the hotter we get, the more we will sweat and the more fluids we will lose. This will result in the loss of important electrolytes, like magnesium and potassium, one of the biggest causes of cramping due to muscles fatiguing faster and then going into a spasm.

 

The loss of fluids can lead to dehydration, a dangerous situation to be in if you don’t take the necessary precautions to ensure that your body is well hydrated at all times. But if dehydration does start to set in and you only fuel with a carbohydrate-rich drink, such as most of the energy drinks off the shelves, the process of fluid uptake will slow down because carbohydrates need water to be carried into the system. So instead of your body using the water to dehydrate the cells or an electrolyte solution to replace the lost important nutrients, it is using most of the fluids in the carbohydrate drink to transport the carbohydrates.

 

Therefore, when the body is dehydrated, all the cells take strain, as the body consist of 70% water, so everything has to work harder under a stressful situation, thus resulting in fatigue.

 

The best thing to do in this situation is to drink plain water with some electrolytes, such as electrona (available from pharmacies) or any rehydration powder, at 500-750 ml per hour.

 

Carbohydrate stores

 

A depletion in carbohydrates can also lead to fatigue and a drop in blood sugar. So, if you train for more than one hour, but less than four to five hours a day, this will result in the depletion of most of your body’s carbohydrate stores. However, if you train at least four times a week, this helps the body to adapt and make certain cardiovascular and muscle changes to cope with the continuous stress and you will use more of your fat stores, thereby saving your carbohydrate stores. But the intensity of exercise will determine what percentage of these stores is used. For example, intense training with your heart rate above 80% will result in the body using a lot more carbohydrates than fat. Endurance-type training with your heart rate under 75%, will result in the body using more fat for energy, thus saving on the glycogen stores.

 

Something else that will adversely affect your carbohydrates, which get stored as glycogen, is the strength of your energy drink solution. So when you are preparing an energy drink, keep in mind that the longer an event, the weaker your energy drink solution must be. This is because of the relatively slower pace you will be performing at, so your body will use more fat and less carbs. This doesn’t mean that you need to cut your carbohydrates, rather take in a lower carbohydrate concentration at a time.

 

The amount of fluid taken in depends on the rate of your stomach emptying and body absorbing it, which is why it's so important that you know what the concentration of your drink should be. The concentration outside the stomach must be higher than inside for it to empty (osmosis effect), so if you keep putting high concentrations of carbohydrates into your stomach, without the necessary fluids (water or an electrolyte solution), the stomach will stop emptying and this can result in vomiting, dehydration, cramping or 'running to the bushes'!

 

Although a depletion in carbohydrates is usually not a serious situation, the loss of important electrolytes can be very dangerous. Furthermore, these factors will be determined by the air temperature and humidity, as well as by the individuals’ physiological characteristics.

 

Less is not more and more is not 100% correct either. It all depends on the individual, duration of exercise, and environmental circumstances. Start listening to your body and get to know how it reacts in different training situations, as this will help you to keep fatigue at bay, train more effectively and reach your goals.

 

Source: Foods, Nutrition and Sports Performance (Scientific consensus organised by Mars and edited by Clyde Williams and John T. Devlin.)