Putting on the brakes

Have you ever watched the start of a workout and observed some athletes start at full speed and “gass out” quickly while others start at a slower pace and eventually overtake the faster athlete?

Or have you had that experience in Fran, usually hitting somewhere in the round of 15, or maybe the round of 9 if you are lucky?  That feeling of burning muscles, gasping for air, not knowing if you can possibly squeeze out one more rep.

If you are new to CrossFit or intense exercise, the feeling of running out of gas can be very disheartening, if not scary.  The experience of gassing out can make you feel like you are literally dying.   If you are an experienced Crossfitter, gassing out frequently in workouts is not only frustrating, but can affect your performance in competitions and ability to set PR’s in workouts.

Gassing out in a workout doesn’t exactly mean that you are doomed for success in CrossFit.   The competitive drive it takes to push you over the edge can prove to be beneficial if you can channel that mental ability and those energy systems in the right direction.  Understanding the science behind energy production and how to manage it can help you achieve peak performance.

So what happens when you run out of gas?  The energy that powers our cellular activity is called ATP (adenosine triphosphate).  It can be generated in many ways and will ultimately provide the energy to create muscular contractions.  Only a small amount of ATP is stored in the muscles and during intense activity it is depleted in about 1-4 seconds.  Now, no one is gassing out 1-4 seconds into a workout, and the reason is that there are intermediate compounds that generate additional ATP after the initial supply is used up.

The first wave is made up of phosphocreatine (PCr).  The breakdown of PCr can fuel maximal exertion for an addition 4-10 seconds.  As the PCr is depleted a separate phase of glycogen rises to meet the demand for ATP.  Glycogen does not deliver the same amount of ATP as PCr so the athlete’s work capacity diminishes slightly.  The moderate level of exertion will be fueled by glycogen and last for about 10-15 minutes.

The first two waves of PCr and glycogen make up anaerobic metabolism (anaerobic meaning without oxygen).  The third wave includes fatty acid metabolism and is where we generate anaerobically (or with oxygen).  This wave builds gradually and has a much lower peak, but can be sustained for long periods of time.  This explains the difference between that athlete who starts out full speed and then hits a wall and slows down and stops versus the athlete who has a steady, calculated pace and can keep going and surpass the other athlete.

Put simply, gassing out is the result of the energy demand surpassing the supply.  To improve this you can focus on producing more energy or better utilizing the energy you already have.

High intensity training like Crossfit is great for improving for aerobic metabolism, even with workouts 10-15 minutes in length.  Regular high intensity training also can stimulate pathways to improve anaerobic metabolism.  Furthermore, recovering properly with good clean protein sources and carbohydrate rich foods such as sweet potatoes can also give this a boost.

Finally, if you are eating right and training at sufficient intensity, you can learn to prevent gassing out by learning how to properly pace yourself through a workout.  A workout like Fran will need to be attacked with a different mindset then a workout like Murph.    But everyone needs to learn how their body functions and reacts to workouts and learn how to pace themselves for different workouts.  If you tend to be someone that starts out too fast and gasses out after a few minutes, try starting out with a slower, calculated pace.  You can always speed up if you realize that you started to slow, but you also may find yourself moving at a more consistent pace with less rest breaks and see yourself getting PR’s in your workouts.  Most importantly, work out at a pace that allows you maintain efficiency and proper range of motion from start to finish!


Federico, Tony. “Running out of gas?.” WOD Talk  March/April 2013: 32-35. Print.

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