I did a metabolic efficiency test two weeks ago at Endurance Performance Training Center in Mill Valley, CA. It was my third time doing one and provided some very useful information. Seeing my results and understanding why knowing your metabolic efficiency is important for an athlete, I decided it would make for (what I hope to be) an interesting blog.
Without going any further though I have to give credit to Tim Fleming for this post. He’s the general manager and head of performance testing at Endurance. Tim provided the majority of content for this blog based on his education and years of experience. Endurance is the ‘home base’ of Achieve’s resistance training sessions and indoor performance testing. There aren’t many facilities in the Bay Area, let alone Marin, set up to do high level performance testing (with all the proper equipment) like Endurance. The main photo if this post illustrates this to a degree.
So without any further ado, why is it important to know your metabolic efficiency? Let’s first get a definition: metabolic efficiency refers to the degree to which fat is utilized as a fuel source at any given intensity during exercise. You may be thinking ‘ok, why do I need to know this?’. Well, if you’re an endurance athlete of any type then you probably know that excess fat doesn’t have a lot of benefits. Sure, it may add a little warmth during the winter months, but the weight of excess fat only slows you down, especially when going up hill. If only gravity didn’t exist. So most of you know that losing some fat will make you lighter (as long as you aren’t replacing it with muscle) which will decrease the effects of gravity and you will go up hill faster. This is always a good thing. Another important questions to understand is: why is it important to utilize fat as a fuel source? Before this is answered, it’s helpful to understand how the body produces energy.
The human body utilizes a combination of fuels to produce energy during exercise. This consists mainly of carbohydrate, fat and a small quantity of amino acids (protein). Carbohydrate provides a constant kindling for other sources of fuel, such as fat, so it is important for endurance athletes to be capable of “sparing” carbohydrate utilization during exercise. However, energy production for muscle contraction during exercise is more efficient when a great percentage of fat is used in the fuel mixture.
Now to answer the questions ‘why is it important to utilize fat as a fuel source?’ Mobilizing more fat to produce energy is efficient for several reason: fat burns more cleanly, thereby reducing metabolic “emissions”, fat has a greater energy density than carbohydrate and burning fat for energy spares limited stores of carbohydrate, resulting in better endurance or stamina. Furthermore, improving fat metabolism provides a great opportunity to reduce excess body fat mass. Another benefit from improved fat metabolism is less dependence on exogenous (from outside a system) sources of carbohydrate during training and competition, therefore reducing the likelihood of gastric distress.
So now that we know why it’s important to utilize fat for fuel, the next question becomes, ‘how does one train the body to utilize it as a fuel source?’ Ultimately, training your aerobic energy system provides better fat burning, and in return, better metabolic efficiency. In addition, another key component is incorporating appropriate nutrition to effectively feed the aerobic system, creating a positive feedback loop for better overall fitness and endurance performance.
All that said, the answer to the first question of ‘why is it important to know your metabolic efficiency?’ should be clear. Now that I’ve done a metabolic efficiency test, I know exactly what effort level (measured in heart rate and power) I have to train at in order to achieve optimal performance during my aerobic endurance phase. This will pay dividends throughout the season.
If you would like to schedule your own test then you can reach out to me at dwilliams[at]achieveptc.com or contact Tim Fleming directly here: http://enduranceptc.com/contact-us/.