Metabolic Testing & Analysis: Number Crunching

In this week’s training tip, I will discuss how metabolic testing & analysis allows both coach and athlete to evaluate the various metabolic pathways responsible for aerobic energy production. For the competitive endurance athlete, having a clear cut understanding of exactly “where” your energy is coming from and how much of it you are using at certain paces or power outputs, provides you with a number of substantial advantages. With this data in hand, you can effectively steer your training, and, when necessary, your nutritional practices, in order to optimize your performance on race day, thereby gaining that much coveted “edge” on the competition!

In one of my previous training tips, “Determination of Aerobic Profile” I talked at length about the use of metabolic testing to determine both VO₂ max and the percentage of VO₂ max at which an athlete’s maximal lactate steady state (MLSS) occurs. MLSS serves as one of the greatest determining factors in an endurance athlete’s performance; all things being equal, the athlete with the fastest pace at MLSS will typically win the vast majority of endurance related events he or she enters… up to a certain point.

For very long events such as the marathon, half ironman (70.3) triathlon or the grueling Ironman triathlon distance, although velocity/power output at MLSS is of critical importance, so too is the athlete’s ability to conserve much needed glycogen stores for the long haul.

We’ve all heard of the terms “bonking” or “hitting the wall” before, and if you’re a hard core fan of endurance racing, you’ve undoubtedly seen it happen to even the world’s best endurance athletes from time to time. In simplistic terms, when an athlete “bonks” they have exhausted their body’s high octane fuel source: muscle glycogen. Muscle glycogen is a substance that is used by the body to provide energy both aerobically (with oxygen) and anaerobically (without oxygen) depending upon the intensity at which the body is operating at. Generally speaking, maximal/near maximal efforts lasting between .01 and 45 seconds, do not require oxygen whereas efforts lasting longer than 45 seconds do. The longer the effort, the greater the role that O₂ plays in energy production (for a more comprehensive look at the three metabolic pathways that are responsible for energy production, click here). Regardless, glycogen is utilized by the body at just about every intensity level, even at rest; the harder the athlete “pushes” during a race or training session, the more glycogen the athlete’s body will “burn” to keep up with energy demand. As efforts approach and surpass MLSS speed/power output, a very high percentage of the metabolic energy yield is derived from glycogen metabolism. For the endurance athlete, this is where the numbers game begins.

Depending upon many factors including, but not limited to: gender, body weight/muscle mass, training and nutritional practices, etc. our bodies store somewhere between 2,000 – 2,500 calories worth of glycogen; enough energy to “only” run somewhere between 20 – 25 miles…. but don’t despair! A well trained, competitive marathon runner will run within 15 – 30 seconds per mile pace of their MLSS pace on race day. Assuming proper training & nutritional practices, glycogen stores will not be depleted late in the race thanks to the fact that the body will derive a good deal of its aerobic energy from the metabolism of free fatty acids (fats!) in addition to its glycogen stores. As such, the dreaded “bonk” is avoided and performance does not suffer late in the game.

Through metabolic testing, we are able to actively assess what percentage of energy is being derived via fat and glycogen metabolism. By doing so, we can “steer” an athlete’s training and nutritional practices to optimize the percentage of glycogen they burn at specific paces/power outputs. In my next training tip, I’ll provide two theoretical examples of how we would go about using testing data to steer the training practices of 2 runners gearing up for the marathon and discuss how testing data would shed light on the different approaches we’d have to take with both runners to ensure their respective success on race day. Stay tuned!

Inspired performance: Remembering Jim Munn as he steps down as GHS track coach - Gloucester, MA - Wicked Local Gloucester

Inspired performance: Remembering Jim Munn as he steps down as GHS track coach - Gloucester, MA - Wicked Local Gloucester

c'est la vie

Longtime GHS track coach Munn to resign

Introduction to Metabolic Testing & Analysis

Let’s get right down to it: For the competitive endurance athlete, the number one objective of any training program is to maximize your degree of event specific fitness. This being said, effective training requires both coach and athlete to first and foremost understand the unique physiological and psychological stressors that the athlete will be subjected to during competition. Simply put, if you expect your body, and mind, to be able to perform at a specific effort, for a specific period of time on a specific course while dealing with specific environmental conditions, your training program must fully prepare you to be able tolerate this very specific set of stressors come race day! As any good coach or athlete understands, event specific, or “specialized” training, is an integral part of the annual training progression; without it, peak athletic performance will not be realized. This being said, we can count on the fact that there is one, and only one approach that every athlete must take when preparing for a given competitive event or distance, right?

Wrong.

Although specialized training is in fact a key ingredient in any successful annual training progression, we must dive deeper in order to gain a complete understanding of each athlete’s unique physiology before undertaking the exact training practices that will yield the peak performance that both coach and athlete are striving so hard for. One of the “laws” of training is that in order for training to be effective, it must be individualized. In order to completely individualize an athlete’s training, we must first understand what kind of aerobic “engine” the athlete possesses, just how strong that engine is, and what kind of fuel economy it’s capable of!

Enter Metabolic Testing & Analysis

Metabolic testing is a term that is often mentioned yet quite often misunderstood. When most people hear the term “metabolic” they immediately think of calories, or basal metabolic rate (the amount of calories your body burns daily, at rest); while metabolic testing can in fact measure an athlete’s BMR, this is just the tip of the iceberg as far as its application is concerned.

In the coming weeks, I will release a series of training tips and vlog posts that will extensively examine the use of metabolic testing & analysis and discuss how its application allows both coach and athlete to attain a thorough understanding of the steps that must be taken over the course of the training progression to ensure that peak performance occurs when it’s needed most. In the coming weeks, I will release a series of training tips and vlog posts that will extensively examine the use of metabolic testing & analysis and discuss how its application allows both coach and athlete to attain a thorough understanding of the steps that must be taken over the course of the training progression to ensure that peak performance occurs when it’s needed most.

I’ve been fortunate enough to team up with Seaside Cycle in Manchester, MA to work on this project. Seaside Cycle recently invested in a New Leaf metabolic testing system, and along with JRM Training, is now offering a wide array of testing services for the cyclist or triathlete looking to maximize their performance potential. This state-of-the-art apparatus, when utilized in conjunction with power (bike) and/or velocity (run) based testing is a surefire way to pinpoint your body’s unique needs as you gear up to approach your event specific training program.

Stay tuned for our next series of vlog posts which will dive deeper into the use of metabolic testing & analysis and how you can best utilize it to maximize your athletic potential in 2010 and beyond.