Hi Carrots ”˜N’ Cake readers! My name is Nicole and I blog over at The Salted Kitchen, where I talk about nutrition, cooking, fitness and travel. I studied nutrition and dietetics in school, and rather than becoming a Registered Dietitian, I went a different route, and am now a food scientist at a large food company. I think my education and career offer two very distinctive views on the food world, and I love incorporating my passion for fitness and travel among it all.
I hope we have some science geeks out there, because today I’m going to discuss the science behind our post-exercise fuel needs. If you’re a Carrots ”˜N’ Cake reader, I can assume you are physically active in one way or another. If you’re interested in improving your performance, it’s critical that you understand the proper way to refuel after exercise. You can increase endurance, strength and improve body composition, simply by fueling properly after exercise, and who wouldn’t want to do that?!
Understanding the Basics
First thing we need to understand is the difference between anaerobic and aerobic exercise. Anaerobic exercise is any activity that does not require oxygen, it’s high-intensity exercise that’s maintained for short durations of time. Sprints are a good example of anaerobic exercise. Aerobic exercise is activity that requires oxygen and can be maintained for long periods of time. Examples are running, cycling, or cross country skiing.
Another important term to understand before going forward is glycogen. When you eat carbohydrates, it enters your bloodstream as glucose, and is taken up in the muscles and liver as glycogen. Therefore, glycogen is the stored form of carbohydrates that is pulled for energy during exercise.
What Does Our Body Use for Fuel During Exercise?
Whenever we do any sort of activity, our body is using a mixture of fats, protein and carbohydrates for fuel. There is never a time when we are exclusively using only one or the other. This is why it’s so important that we maintain a balanced diet with all themacronutrients.
Depending upon the type and duration of exercise, you will use different ratios of these macronutrients. Protein is consistently providing about 10% of our energy during exercise – whether its anaerobic or aerobic. Glycogen is the primary source of fuel in any form of exercise. In aerobic exercise, the longer you maintain that activity, the more and more fat you will use for fuel, unless you replenish your available glucose. When aerobic athletes use up their glycogen supply (which is around 2000 calories worth), they need to provide available sources of glucose for immediate energy (sports drink, goo packets). If they don’t they will continue to use more and more fat for fuel, and will experience fatigue and what many describe as "hitting the wall". The diagram below illustrates how our bodies use more and more fat for fuel the longer we exercise.
What Should You Eat After Exercise?
Whether you’ve finished a long run or lifted weights, your number one priority after exercise should be replacing fluids. Drink fluids of some kind – water, sports drink, coconut water, etc. What you choose to drink is largely dependent upon what activity you did and for what duration. Typically, sports drinks should be reserved for exercise lasting more than 60 minutes, or when exercising in extreme heat. Read more about coconut water, and when it’s best to consume, here. Aim for 20-28 ounces of fluid for every hour of exercise to ensure proper hydration.
Second priority is replenishing your glycogen stores with a carbohydrate source, ideally 15-45 minutes after your workout. Research has found that if a high-carbohydrate meal is eaten within 15 minutes after exercise, the rate of glycogen storage accelerates by 300%. If you wait longer than two hours after your workout to refuel, your glycogen storage capacity declines by half, and your protein repair by 80 percent! By eating soon after exercise, you are not only replacing lost glycogen, but increasing your glycogen capacity so you have more energy (and therefore, endurance) the next time you exercise. So, make it a priority to refuel no more than two hours after your workout. The sooner you can do it, the better! Aim for 30 – 60 grams of carbohydrates for every hour of exercise.
To further improve your glycogen storing capability, eat a carbohydrate and protein source together. Research has found that when protein is added to carbohydrates, blood insulin levels increase. Blood insulin stimulates glucose uptake in the muscle (which converts to glycogen) and increases the rate of protein synthesis. The optimal ratio is 4:1 (four grams of carbohydrates for every gram of protein). Research has found that those who refuel with this ratio of carbs to protein have twice the glycogen stores as those who only eat carbohydrates.
When you exercise, your muscles become very sensitive to certain hormones and nutrients. This is the perfect opportunity for athletes to provide the right nutrients to improve performance. The increased sensitivity only lasts for a limited amount of time, so it’s very important to use this window of opportunity.
Here are some examples of good post-workout snacks:
- cereal with milk
- fruit with greek yogurt
- toast/bagel/english muffin with peanut butter or cheese
- cottage cheese with fruit
- chocolate milk (scientifically proven to be one of the best post-exercise recovery aids!)
- smoothie made with a protein source (milk, yogurt or protein powder)
- piece of bread with sliced turkey
If you have any questions, please feel free to email me at firstname.lastname@example.org!