A balanced and nutritious diet is imperative to optimizing your health and wellness. Now couple your knowledge on healthy eating with more insight on sports nutrition, and you begin tapping into your potential as an athlete. Everyone has different goals, whether it be to stay in shape, improve performance, or compete as a professional athlete. The field of sports nutrition is ever growing and vast in its studies and guidelines.
This peak into the keyhole of sports nutrition aims not to get into every detail, but rather seeks to appeal to different individuals’ interests and stages of their fitness and nutritional journey.
Nutrition is a valuable asset in sport; and if done correctly can optimising training and performance. Our bodies use its nutrient stores and reserves in order to generate energy to be used up during physical activity. Hence, additional energy/ nutrient intake needs to be accounted for to ensure that we still have adequate energy left for baseline physiological function. In other words:
Daily nutritional intake – Energy expenditure should
= Energy available for baseline physiological function
Carbohydrates are important for physical performance for the reason that they are our main source of energy. Carbohydrates are broken down into different smaller forms, including glucose which is used for energy. Any unused glucose is converted and stored as glycogen in our liver and skeletal muscle. The amount of carbohydrates we require can be influenced by factors such as duration, intensity, frequency, type of exercise and even environmental conditions.
Carbohydrate prior to exercise
A high carbohydrate meal 4 hours prior to exercise has shown to increases glycogen stores in our muscles and liver. Remember, glycogen is converted back to glucose to be used to make energy (fuel) for our bodies to use.
1 – 4g/kg carbohydrates is recommended to be taken 1 – 4 hours prior to exercise, if the duration of exercise is expected to last >60min.
Low GI foods may be a more sustainable source of energy if carbohydrates cannot be consumed during the workout.
‘Carbohydrate loading’ refers to the consumption of meal(s) which are very high in carbohydrates. This strategy may be beneficial for events that will last >90 minutes. This can be done by eating a high amount of carbohydrates 3 – 4 days prior to exercise. Carbohydrate loading may not be necessary if a high carb meal is taken prior to exercise and carbs are ingested during the exercise.
Don’t get a fright. You may experience weight gain, since every gram of glycogen stored there is additional 2,7g water stored.
Carbohydrates during exercise
Eating Carbohydrates during exercise can aim in the prevention of hypoglycaemia (low blood sugar), promotion of sustained energy intensity, provision of additional fuel for muscles when glycogen stores are depleted) and stimulation of the pleasure and reward centres of the brain. Recommendations of carbohydrates during exercise:
Carbohydrates after exercise
Recovery post-training is essential for ensuring intensified and continued performance.
Carbohydrate intake 30 – 60 minutes after exercise does not require insulin to be absorbed.
Recovery for glycogen stores:
o Fast recovery: 1.2g/kg/hr repeated for 5 hours (helps to maximise glycogen restoration).
o Longer recovery: >8g/kg/day (helps to maximise glycogen restoration within 24hours).
There is little significant research that proves than ingesting high GI carbohydrate meals will replenish glycogen stores better than low GI carbohydrate meals; provided that adequate amounts of carbs are ingested after exercise.
Protein requirements: 1.0 – 2.0g/kg for a physically active adult.
Here are some examples:
Endurance athlete: 1.2 – 1.4g/kg
Elite endurance athlete: 1.6 – 2.0g/kg
Regular resistance training: 1 – 1.2g/kg
Power sports (e.g.: Rugby): 1.4 – 1.7g/kg
Different sources of protein have different bioavailability values- I explain more about bioavailability in my previous blog about plant-based proteins. Bioavailability is the measure of which a substance is absorbed by the body. Food sources such as chicken, fish, egg white and milk are high quality protein sources.
The timing of protein intake is important and can aid maintenance of lean body muscle, immune function and growth. Protein requirements should be individually determined based on factors, including but not limited to: type of exercise, duration and intensity of exercise, age and gender
Evidence suggests that animal proteins may be benefit muscle mass and strength gain above plant-based protein sources.
Protein before training:
0.15 – 0.25g/kg Protein + 1 – 2g/kg Carbohydrates 3-4 hours prior.
Protein during training:
Carbohydrates with protein may be beneficial in enhancing performance and decreasing muscle damage.
Protein after training:
Protein should be given to the body as soon as possible post exercise; this may help to maintain and repair muscle.
A combination of protein and carbohydrate, within 3 hours of exercise, may assist in muscle protein synthesis.
The recommended ratio of carbohydrates to protein is 4:1. A practical example of a good post- workout snack is a flavoured milk drink.
It is recommended that you also see the blog post on Intuitive Eating, as it examples the different types of fats in greater detail.
Fat recommendation is 20 – 35% of total energy intake. Or, 0.5 – 1.0g/kg/d fat if body fat loss is desired. Again, it is important to consult a dietitian to calculate your requirements and how to practically apply this advice to your everyday life.
The type of fats we consume plays a role in our overall balanced plate of food. Try prioritising lean protein sources and ‘healthier’ fats:
Avoid saturated- and trans-fatty acids:
o I.e.: Animal fats, processed foods fast foods), ice-cream, baked goods...
Accommodate unsaturated fatty acids:
o Preference to Monounsaturated Fatty Acids, being: avocados, nuts, olives and olive oil
o As well as Polyunsaturated Fatty Acids, namely: Sunflower oil, corn oil, soft margarine, fatty fish, corn oil.
Now that we’ve covered our macronutrients, let’s touch a bit on a few other topics... Micronutrient supplementation (vitamins and minerals) is not needed for athletes if they sufficient intake of a variety of foods; unless they are vegetarian, ill, recovering from injury(s) or a medical condition (in which case a dietitian/ doctor should be referred).
Always stay well hydrated. Both over-hydration and dehydration can have negative consequences. Dehydration can lead to decreased performance, increased fatigue, muscle cramps, headaches and even disorientation.
Prior to exercise or a competition:
Slowly drink 5 – 10ml/kg of water 2 – 4 hours prior to exercise. If your urine is very dark/ concentrated, have 3 – 5ml/kg water 2 hours prior to exercise.
Drink 90 -120ml per 15 min during endurance events.
Always rehydrate after exercising.
Eat wholesome, natural foods to help replenish depleted electrolytes.
Salty snacks can help to replenish sodium levels and increase absorption of water.
WEIGHT LOSS FLUID
‘Relative Energy Deficient Diets’ have shown to impair physiological function, i.e.: metabolism, menstrual cycle, immunity, muscle building and even bone health; as well as impair performance and muscle strength, increase risk of injury and decrease motivation. Healthy and gradual weight loss is 0.5kg/week; and can be achieved through mild dietary restrictions together with exercise. Large fluctuations in weight should be avoided. Having a low intake of carbohydrates can lead to low energy/ glycogen stores. The side effects of low glycogen stores includes: reduced ability to perform high intensity exercises, reduced power of movement and increased risk of injury, illness and overtraining.
Proper nutrition can help to optimize recovery, maintain and promote immune function, manipulate body compensation and enhance performance. All you need is a little more discipline, the application of sports nutrition insight and the guidance of a qualified dietitian.
Ref: Burke LM. Fueling strategies to optimize performance: training high or training low? Scand J Med Sci Sports 20(Suppl. 2);2010: 48-58.