A couple of weeks ago, I participated in a 5k and a 10k challenge that was scheduled 12 hours apart. Fitness enthusiasts would consider a back to back 5k / 10k as just another training session. I, on the other hand, am quite the opposite. I have developed a hate-hate relationship with aerobic exercise –specifically, running. I like speed, agility, quickness, strength, and power – arrg arrg arrg! I am five foot nothin’ and a hundred somethin’ (emphasis on the nothin’ and somethin’). I would rather pluck my eyelashes than run. But, I do love the exercise science.
You’d think I’d use my knowledge for exercise science as a useful tool. Unfortunately, my continued pursuit of knowledge does not translate to practical utility. What follows is what I should have done to enhance recovery and optimize performance during this short 12 hour recovery period between races. Since, I won’t listen to myself, maybe you will!
First, we must understand the physiology of producing energy, fatigue and recovery. I do not want to turn this in to an advanced exercise physiology session on metabolic pathways but this general background is helpful. When we exercise energy (ATP) is needed. This energy is created by our body using three systems: ATP-PCr system, the glycolytic system and the oxidative system. Each energy system has its own method of generating energy. Likewise, each energy system becomes fatigued after an imbalance occurs in its system.
In the ATP-PCr system our body uses stored Phosophocreatine and through a series of reactions quickly generates ATP. Unfortunately, this system gets depleted of stores rather quickly. This is why you can only perform and all out sprint for 10 – 20 seconds. After a 2 minute rest period the ATP resynthesizes giving you the ability to perform an all-out sprint again. If we going longer than 20 seconds our body must enter the glycolytic system. Here we begin to use glycogen to make energy. When glycogen is broken down without oxygen present, our cells becomes acidic (commonly known as lactic acid buildup or lactate threshold). This acidity inhibits enzyme activity. Since enzymes are the catalysts for almost all body functions, we fatigue when they stop working.
If intensity is low enough in the glycolytic system, our body has time to use oxygen to breakdown glycogen and prevent lactic acid build-up. This is the oxidative system. Using oxygen to breakdown glycogen is our long-term energy system, which we use to perform tasks like distance running. Carbohydrate is stored in our body as glycogen in muscle and liver. This is our preferred and primary energy source. However, when we exercise we deplete glycogen stores and sometimes have to call on fat to make energy. When we reach this phase our body will fatigue. So, in review, during high-intensity exercise we fatigue because we deplete ATP and Phosphocreatine stores. During moderate activity we fatigue due to lactate build-up. During long and steady state exercise we fatigue when glycogen stores become depleted.
To combat this fatigue we must train our body to adapt to these physiological changes, or provide opportunity for our body to recover through rest. You can also practice good post-exercise refueling habits. By eating and drinking macronutrients (carbohydrate, fat and protein) we replace what we just used. So, what do we eat and when do we eat to replenish?
A Study published by Howarth, et al., in 2009 found that ingesting a carbohydrate and protein mixture at a 4:1 ration provided the best benefits when compared to carbohydrates alone. Similarly, Koopman, et al., in 2005 found a 3:2 ration of carbohydrate to protein ingested post exercise was better than carbohydrate alone. The Koopman study also investigated the benefit of leucine – an essential amino acid found in soy, beef and salmon, known to facilitate muscle regeneration – and demonstrated an added benefit of this supplement. Even though some current data is contradictory most studies show that the amount of glycogen formed is significantly greater in athletes consuming the mixture of Carbohydrate and Protein.
Timing also plays an important role. You may have heard of nutrient timing – it’s getting a lot of attention lately. In order to compensate for protein loss during exercise, the timing of post-exercise protein supplementation is important. The efficiency of protein synthesis is improved by ingesting rapidly after exercise. Another challenge is the refueling with carbohydrates. Bottom line, the sooner carbohydrate is consumed post-exercise; the greater the amount of muscle glycogen is resynthesized. When time is short between fuel-demanding events, it makes sense to start refueling as soon as possible.
Keep it simple, post-exercise meals should be built on a foundation of carbohydrate-rich foods plus a smaller amount of protein. Greek yogurt or cottage cheese with fruit or bananas with peanut butter are both good options. If you are a stickler for protein powder, switch it up – make yourself a fruit smoothie and add a scoop of protein.
My times for the 5k and 10k were 29:37 and 63:26 respectively; certainly not awesome. Maybe if I’d apply what I know, I would have done better. Maybe if I replenished with a healthy carbohydrate protein drink instead of beer and pizza, I would have done better on day 2. If I’d just listen to my brain and not my fat cells I might have finished under 60 minutes. If I’d listen to my brain, not watch the ESPN, I could improve. If I chose to get up rather than drool on my pillow, I might approach 45 minutes. Someday I will get the hint and practice what I preach. Maybe I need the late Chris Farley’s famous character, Matt Foley, as my personal motivational speaker.