Post-Exercise Nutrition
We are all aware of the many health benefits of exercise. However, exercise, especially strenuous, high intensity, or prolonged exercise causes stress on the body; it may cause damage to muscles, wear and tear on the joints, increased free radical production, and an inflammatory response. Symptoms may include muscle soreness, aches and pains, inflammation, tiredness, heaviness and an increased appetite. These side effects may indicate that body tissues are damaged and that fuel stores are depleted and need replenishing. It is after exercise that the muscles rebuild and get stronger. This is called remodelling and it can only take place if the raw materials for growth and repair are available.
This month’s blog posts will look at how to nourish the body after exercise to improve recovery and restore energy. What you consume before, during and after your workout can affect antioxidant status, recovery time, muscle strength, body composition, performance and immune health.
It’s important to remember that exercise depletes stored carbohydrates and breaks down protein. After exercise the muscles are especially receptive to absorbing and utilising protein, carbohydrates and other nutrients.
Damage Caused by Exercise
Exercise, especially intense or prolonged exercise, damages our tissues at the microlevel. It also uses up fuel. It is how we behave after exercise that determines how well we recover and how much muscle growth results from the workout.
Repair and rebuilding occurs through the breakdown of old, damaged proteins (protein breakdown) and the construction of new proteins (protein synthesis). Overall this is known as protein turnover. The relationship between the rate of muscle protein synthesis and breakdown provides the basis for muscle growth.
Protein is not the only concern as during exercise carbohydrate stores are depleted.
The main aims of post-exercise nutrition are to:
- Replenish glycogen – glycogen is the storage form of glucose, our major source of energy. It is depleted from the muscles during exercise.
- Increase protein synthesis – this aids muscle and tissue repair and increases muscle size and quality.
Increased blood flow to skeletal muscle during and after exercise means that nutrients are being moved around the body to where they are needed more quickly for rapid utilisation.
Post-exercise nutrition requires:
Carbohydrates – It’s recommended to consume sufficient carbohydrates to stimulate insulin release following exercise. Insulin is the hormone that carries carbohydrates and amino acids into the muscle. In doing so muscle glycogen stores are replenished and protein is available for repair of muscle tissue. Research has shown that a carbohydrate intake of about 0.8 – 1.2 grams per 1 kilogram of body weight soon after exercise maximizes muscle glycogen synthesis and accelerates protein repair. The co-ingestion of protein with carbohydrate can assist glycogen storage (1,2,3).
Protein – since muscle protein is degraded during exercise, ingesting protein after exercise is necessary to stimulate muscle protein synthesis and to rebuild muscle. After exercise, the body decreases its rate of protein synthesis and increases its rate of protein breakdown. However, the provision of protein and amino acid solutions after exercise reverses this trend, increasing protein synthesis and decreasing protein breakdown.
Research recommendations vary in terms of how much protein to ingest after exercise. It seems between 20 – 30g of rapidly digestible protein isolate optimizes muscle protein synthesis rates during the first few hours of post-exercise recovery (4,5). Other researchers have used from 0.2g-0.4g of protein per 1 kilogram of body weight added to the post-workout carbohydrate drink.
Providing an amino acid and glucose dense blood supply during and after exercise means that the rate of protein synthesis goes up and glycogen stores are replenished.
Benefits of good post-workout nutrition include:
- Faster and better recovery
- Reduced muscle soreness
- Increased ability to build muscle
- Improved immune function
- Improved bone mass
- Improved ability to utilise body fat
- Improved performance in the next workout
- Improved muscle to fat ratio
- Reduced risk of injury
Protein and carbohydrates can come from a meal containing healthy sources of protein and carbs. However, not everyone feels like eating a hearty meal directly after exercise and whole foods digest slowly meaning the nutrients won’t be immediately available. Often a nutritious drink containing protein, carbs and other nutrients is a better option straight after exercise. See the blog post Nourishment During the Window of Opportunity for information about post workout drinks and other foods to aid recovery after exercise. See also the blogpost Nutrients for Post-Exercise Recovery for information about which nutrients to consume after exercise.
References
1. 2018 Feb 23;10(2):253. Restoration of Muscle Glycogen and Functional Capacity: Role of Post-Exercise Carbohydrate and Protein Co-Ingestion. Alghannam A et al.
2. Aust J Sci Med Sport. 1997 Mar;29(1):3-10. Nutrition for post-exercise recovery. Burke LM.
3. J Appl Physiol (1985). 2017 May 1;122(5):1055-1067. Postexercise muscle glycogen resynthesis in humans. Burke LM et al.
4. Am J Clin Nutr. 2020 Aug 1;112(2):303-317. Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial. Churchward-Venne TA et al.
5. Sports Med. 2019 Feb;49(2):185-197. The Muscle Protein Synthetic Response to Meal Ingestion Following Resistance-Type Exercise. Trommelen J et al.