If you're a CrossFit athlete then you probably know that feeling well - that feeling during a workout when you suddenly "hit a wall." You're doubled over, hands on your knees, thinking that the bar feels so much heavier than it did before and it's going to be a miracle if you make it out of this WOD alive. You let your heart rate come back down and you manage to finish the workout. It's painful. It's slow. It's very disappointing.
Why does this happen? Why do we suddenly hit a wall during a workout. We've been here before. We've lifted this much before. But today, right now we're feeling more exhausted than we thought possible.
Can we prevent it from happening completely? Probably not. But can we delay it? Can we extend the duration and intensity of exercise that we're performing before it occurs? Absolutely. It's all about understanding the concept ofMetabolic Efficiency Training and its relationship to CrossFit.
Metabolic efficiency is a term that describes the body's ability to utilize its internal stores of carbohydrate and fat for different intensities and duration of exercise and at rest. More specifically, it's about teaching your body to use its almost unlimited fat stores for energy and preserve its extremely limited carbohydrate stores.
Why does this matter? Metabolic efficiency plays a key role in maximizing our workouts since it can help stave off glycogen depletion, a major nutritional factor that can dramatically limit performance for CrossFit athletes.
In the example above, hitting that "wall" is your brain sensing rapidly decreasing glycogen levels and its consequent attempt to slow the body down in order to conserve energy.
The body only has between 1,300 and 2000 calories stored as carbohydrate (i.e. glycogen) in the liver and muscles, whereas it has up to 80,000 calories of internal fat stores. Improving metabolic efficiency results in increased oxidation of these fat stores both at rest and during exercise. This preserves glycogen for use during higher intensity exercise when it is most needed.
It is likely that you have heard of this scenario before as it applies to exercise: as intensity increases, the body prefers to use more carbohydrate and less fat for energy. While it is true that you will burn more carbohydrate at higher intensities of exercise, the point at where your body crosses over from mostly fat to carbohydrate usage is highly adaptable.
Let's compare Sally and Dan.
Sally is fairly metabolically inefficient. She is a "carbohydrate burner" and her body prefers to use carbohydrate as a fuel source, even at rest. While Sally is walking her dog in the morning, cleaning her house, and sitting at her desk at work, her body is utilizing its glycogen for energy rather than its fat stores. Sally heads to CrossFit after work and she finds herself struggling through the WOD within a few minutes. She is frustrated that she is always one of the last to finish even though she considers herself a fit and athletic individual.
Dan is metabolically efficient. His body prefers to use its internal fat stores for energy, even at higher intensities of exercise. While Dan is driving his kids to school and meeting with clients at work, his body is burning fat and preserving his glycogen. Dan goes to CrossFit after work and is able to push himself hard throughout the entire workout. He is always one of the first to finish, he recovers well, and his performance at the box improves every day.
Dan has the advantage over Sally during workouts because his body is able to tap into his unlimited stored body fat for energy throughout the day. Then, when he goes to CrossFit and exercises at a high intensity, he has the glycogen stores necessary to fuel his workout. Sally, being metabolically inefficient, uses up most of her glycogen stores throughout the day. She is not able to maintain high intensity exercise for very long before hitting the wall.
Metabolic Efficiency Training
So how do you become more metabolically efficient? The answer is in your daily nutrition plan.
The concept of metabolic efficiency centers on the control and proper management of blood sugar. Eating too many refined carbohydrates or eating a large amount of carbohydrates at one time leads to an increase in the use of carbs for energy. Whenever blood sugar rises, the pancreas secretes the hormone insulin in order to reduce blood sugar. However, as insulin increases, fat oxidation significantly decreases and eventually turns "off". Having consistently high insulin levels throughout the day in response to uncontrolled blood sugar makes it incredibly difficult for your body to utilize its internal fat stores for fuel.
So how do you control your blood sugar?
By focusing on protein, fat, and fiber.
It is these three nutrients that, when eaten together, will balance and optimize your blood sugar and control your hormone levels to allow for greater fat burning. Choose quality protein sources such as meat, eggs, and fish, and healthy fats such as avocado, full-fat dairy, nuts, coconut oil, chia seeds, pastured butter, and olive oil. Focus on vegetables and fruits and occasionally whole grains for your carbohydrate (fiber) sources.
Metabolic Efficiency (ME) training is not a calorie-deficient diet, nor is it a Paleo, ketogenic, or low-carb diet. Eating to become more metabolically efficient is a lifestyle adaptation. It will take preparation and commitment on your part. Controlling blood sugar through proper food selection is the key take-home message. By pairing protein, fat and fiber-rich foods together at the majority of your meals and snacks, you will soon find yourself delaying or even preventing that dreaded "wall" during a WOD that all CrossFitters have stood before.