PART THREE - Sports Nutrition
A five-part series on nutrition and health,
by Jenna Selley
A balanced and nutritious diet is imperative to optimising your health and wellness. If you couple your knowledge on healthy eating with more insight on sports nutrition and you will 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 does not aim to delve 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 optimise training and performance. Our bodies use its nutrient stores and reserves in order to generate energy that is to be used up during physical activity. Hence, additional energy or nutrient intake needs to be taken into account to ensure that we still have adequate energy at our disposal for baseline physiological functions. In other words:
(Daily nutritional intake – Energy expenditure should
= Energy available for baseline physiological function)
NB: It is important to consult a dietitian to calculate your nutritional requirements; and seek education on how to effectively attain your nutritional needs.
Carbohydrates are important for physical performance as 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. The most effective strategy to improve muscle gain and strength is resistance training in combination with sufficient carbohydrate and protein intake.
Carbohydrate intake during exercise can help maintain blood glucose levels and fuel muscles, and carbohydrate intake after exercise can replenish glycogen stores and maximise skeletal muscle protein balance (i.e.: the balance between building and breaking down muscle).
Carbohydrate intake prior to exercise:
· A high carbohydrate meal 4 hours prior to exercise has shown to increase glycogen stores in our muscles and liver. Remember, glycogen is converted back to glucose to provide energy (fuel) for our bodies to use.
· 1 – 4g/kg of carbohydrates is recommended to be ingested 1 – 4 hours prior to exercise, if the duration of exercise is expected to last longer than 60 minutes. “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 more than 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 slight weight gain, as there is an additional 2,7g of water stored in every gram of glycogen.
Carbohydrates during exercise:
· Eating Carbohydrates during exercise can assist in the prevention of hypoglycaemia (low blood sugar), the promotion of sustained energy intensity, the provision of additional fuel for muscles when glycogen stores are depleted and the stimulation of the pleasure and reward centres of the brain.
· Recommendations of carbohydrates during exercise:
Carbohydrates after exercise:
· Post-training recovery is essential for ensuring intense and continued performance.
· Carbohydrate intake 30 – 60 minutes after exercise does not require the absorption of insulin.
· Replenishment of 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 to prove that 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.
Different sources of protein have different bioavailability values, which I dealt with previously in my previous blog-post 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. Evidence suggests that animal proteins may benefit muscle mass and strength gain above plant-based protein sources.
The timing of protein intake is important and can aid in the 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.
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
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- workout; this may help to maintain and repair muscle.
· A combination of protein and carbohydrates, 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 my blog post on Intuitive Eating, as it explains 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 in order 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:
o Avoid saturated- and trans-fatty acids:
I.e.: Animal fats, processed foods, fast foods, ice-cream and baked goods etc…
o Accommodate unsaturated fatty acids:
Preference to Monounsaturated Fatty Acids, being: avocados, nuts, olives and olive oil;
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 maintain a sufficient intake of a variety of foods; unless they are vegetarian, ill, recovering from injury(s) or have a medical condition (in which case a dietitian or doctor should be referred to).
Always stay well hydrated. Avoid over-hydration or dehydration. 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.
· Avoid alcohol.
Weight loss in Sports:
‘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 or glycogen stores. The side effects of low glycogen stores include: reduced ability to perform high intensity exercises, reduced power of movement and increased risk of injury, illness and overtraining.
Different people have different opinions on performance enhancing supplementation.
Several studies have shown that having excessive protein can lead to higher fat stores with no significant effect on muscle mass gain, beyond a certain amount. Let’s briefly talk about a few.
Whey protein is a complete protein, meaning it contains all 9 essential amino acids. Serving sizes range between 20 – 22g per serving which is the equivalent to ±90g of meat. Whey can be seen as an alternative form of protein intake. It is not necessary to prioritise having a ‘protein shake’ as the only means of attaining your muscle mass goals. Proper portion sizing of food and choice of protein source can prove sufficient to meet your protein requirements.
Some vegan options of protein sources include Soy protein, Pea protein, Hemp protein and Rice protein.
Creatine has been proven in several studies to be beneficial in muscle gain. It can lead to weight gain, which presents initially as an increase in water retention and only later as muscle synthesis.
It may also cause gut discomfort. Creatine can also be found in red meat (4.5g/kg).
Meal replacements are a method of controlling calorie intake and help with weight loss; however, caution must be taken not to become over reliant and dependant on these formulas. Meal replacements should not serve as the sole or primary source of nutritional intake especially over a long period of time.
Probiotics may be a recommended for gut health and support of the immune function.
Caffeine has shown to increase mental alertness and reaction time of athletes and increase force of muscle contractions. It can unfortunately also increase nervousness/ anxiety, act as a diuretic (causing frequent urination), cause dizziness and gut discomfort. The effects of caffeine will be best experienced at 30 – 90min after ingestion.
Remember, if you have accounted for a balanced and healthy diet and lifestyle, with the addition of incorporating sports-based nutrition intake, then the need for supplementation becomes almost void.
Proper nutrition can help to optimise 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.
Additional sources: Burke LM. Fueling strategies to optimize performance: training high or training low? Scand J Med Sci Sports 20(Suppl. 2);2010: 48-58.