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J Strength Cond Res. 2017 Oct; 31(10): 2920–2937.
Published online 2017 Jul 19. PMCID: PMC5640004
Glucose
Glucose functions as the primary energy source. Unlike fats and proteins (e.g., ketones), which the body uses as energy sources in some conditions, glucose is the only energy substrate in the body that functions solely for providing energy to cells. Circulating glucose levels during exercise depend on energy status, food intake, event intensity, and glycogen storage levels. Reduced glycogen availability is commonly associated with fatigue.
With glucose-depleting events, carbohydrate consumption before or during prolonged exercise has been shown to replenish glycogen, maintain blood glucose levels, and enhance performance, especially for high-intensity activity.
As exercise intensity increases, VO2max will increase accordingly:
• 30% VO2max is equivalent to a comfortable walking pace • 60% VO2max is equivalent to a jog • 75% VO2max is equivalent to a fast running pace
As you can see, muscle glycogen stores are depleted faster as exercise intensity increases. After 90 minutes of exercise at 75% VO2max, about 80% of muscle glycogen stores are depleted (Sherman et al, 1988).
This slide shows the consequences of not replenishing glycogen stores after an exercise session on subsequent sessions over a number of days.
After a prolonged exercise period the glycogen stores in our muscles will be reduced because glycogen has been used to provide energy during exercise. If we consume a high carbohydrate diet after exercise, our muscle glycogen stores will be quickly replenished and by the time we begin to exercise again the next day, they will be almost back to where they were on Day 1 and we will be able to perform at least as well in our next exercise session.
Adequate nutrition for a given training volume can reduce the risk of exercise-induced hypoglycemia in athletes. In addition, exercise training may reduce vulnerability to hypoglycemia in athletes because of a shift in substrate metabolism. However, overtraining may reverse this adaptation, making athletes more vulnerable to hypoglycemia in the over-trained state.
Pre-match meal
This is a carbohydrate-rich meal that is eaten about 3 hours before exercise begins. Try eating a bowl of pasta or rice with some meat or veg or a couple of sandwiches and a banana.
Pre match snack
This is a carbohydrate-rich snack eaten about 1 hour before exercise. Try eating an apple or banana with some nuts. Also within 30 minutes of training you should top up your carbohydrate stores by drinking a sports drink or eating an energy bar.
During training
It’s best to drink water as well as 30-60g of carbohydrate per hour of exercise. This can be achieved by drinking 500-1000ml of Lucozade Sport, having 1-2 sports gels or eating a couple of bananas.
Post training
The aim is to eat 1g of carbohydrate /kg of body weight per hour for 2-4 hours. So if you weight 80kg you would need to eat about 320g of carbohydrates in the 4 hours post exercises. Therefore you could use the carbohydrate content of foods is the previous post to workout what you need to eat to replenish your muscle glycogen stores.
References
Sherman, W. M. and Lamb, D. R. Nutrition and Prolonged Exercise. In: Perspectives in Exercise Science and Sports Medicine, Volume 1, Prolonged Exercise (Lamb DR and Murray R, eds), pp213-280. Benchmark Press, USA. 1988.
Fats
Fat utilization during exercise impacts lipid profiles by reducing resting levels of total cholesterol and triglycerides, thereby improving cardiovascular health profiles.
In addition to providing energy, some types of fats play important roles in recovery. Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) reduce inflammation, muscle soreness, and the perception of pain from exercise.
Moreover, omega-3 fatty acids may influence performance through their effects on neuromuscular function, nerve conduction velocity, and neuromuscular sensitivity of the acetylcholine receptor. In addition, omega-3 fatty acids may support increased training volume and support adaptations to exercise training. Levels of omega fatty acids measured in the blood reflect their clinical role more so than dietary intake.
Nevertheless, the recommended daily intake of omega-3 fatty acids (EPA + DHA) is ≤3 g·d−1 for average individuals or those moderately physically active, but recommendations may be as high as 6–8 g·d−1 (2:1 ratio of EPA:DHA) for elite athletes. Greater training demands may increase requirements for omega-3 fatty acid intake.
Optimal nutrition is one of the most important determinants of healthier ageing, reducing the risk of disability, maintaining mental and physical functions, and thus preserving and ensuring a better quality of life. Dietary intake and nutrient absorption decline with age, thus increasing the risk of malnutrition, morbidity and mortality. Specific nutrients, particularly long-chain omega-3 polyunsaturated fatty acids (PUFAs), might have the potential of preventing and reducing co-morbidities in older adults.