Carbohydrates for Sports Performance

The primary purpose for carbohydrates is to provide energy for the brain and muscles. It is also the preferred macronutrient used by the body for energy so it is an important part of a sports performers diet. Carbohydrates are stored within the muscles and liver in the form of glycogen.

Glycemic Index

Carbohydrates can be separated into three groups which are part of the glycemic food index. The first category is the high glycemic index foods and are typical foods such as bagels, white bread and doughnuts. The second category is called moderate glycemic index foods and includes white rice, cereal and pita bread. The final category is called low glycemic index foods and examples of these foods would be beans and milk. 

The reason carbohydrates are split into these categories is because our body reacts differently due to the contents of the nutrient. For instance, this diagram shows a high glycemic food (white bread) and a moderate-low glycemic food's effect on our blood sugar response. Due to high glycemic foods having more glucose in them, our blood sugar levels increase rapidly after eating and then suffer a big drop after an hour. Whereas, a moderate-low glycemic food increases blood sugar levels more evenly over a longer period of time. This is important for a sports performer to understand because different types of carbohydrates will give us different functions. Depending on what sport you are participating in it may be beneficial to consume different types of carbohydrates.

Pre Exercise CHO Requirements

The aim of a pre exercise meal is to maximise the muscle and liver glycogen stores ready to be used during exercise.

A power lifter is performing at a high intensity for a short period of time. More glucose will be expended within a short period of time; therefore it needs to be provided priory to exercise. It would be more beneficial for a power lifter to consume high glycemic foods around 15 minutes before competing. This is because they require a big boost of energy to work at high intensity, high glycemic foods would be perfect for this under an hour. 

Contrasting this sports performer with a marathon runner who is working at a less intensity but require to last longer; because of the lower intensity the carbohydrates need to provide energy for the marathon runner for over 2 hours. Therefore, moderate to low glycemic foods should be apart of the pre exercise meal. The ideal time to eat prior to exercise is 2-4 hours.

Pre Event Nutrition Preparation (2015) states: 'Research suggests that endurance performance is improved when athletes consume a substantial amount of carbohydrate (200–300g) in the 2–4 hours before exercise.'

Therefore, consuming 1-5 grams of Carbohydrate per KG of BW 2-4 hours before exercise would benefit a sports performers performance. If I followed this guideline in my practice I should include between 79-395 grams of CHO in my pre exercise meal.

The video above gives an insight from a professional nutritionist and dietitian on the types and amounts of food that is good to eat before exercise.

Post Exercise CHO Requirements

According to IOC (2015) 1-2 grams of CHO per KG of BW is recommended to be included in your post exercise meal. The meal should be consumed up to 4 hours after completing exercising. Post exercise I should have 79-158 grams of carbohydrate in my meal. 

Refrences:

IOC (2015) Carbohydrate for competition [Online] Available from: http://vle.chesterfield.ac.uk/course/view.php?id=3196 [Acessed 2015]

LIFESTYLE MEDICINE (2013) The Glycemic Index Explained [Online Video] December 2013 Available from: https://www.youtube.com/watch?v=F1YDR2S7SPU [Acessed 2015]

MonkeySee (2013) What to eat before exercise [Online] Available from: https://www.youtube.com/watch?v=ou37Js1mzEU [Accessed 2015]

Class Notes (2015) Carbohydrate for Sport Performance [Online] Available from: http://vle.chesterfield.ac.uk/course/view.php?id=3196

Pre Event Nutrition Preparation (2015) Pre Event Preparation [Online] Available from:  http://vle.chesterfield.ac.uk/pluginfile.php/283037/mod_resource/content/1/Pre-Event%20Nutritional%20Preparation.pdf