Finding the ratio: Why do we rest during workouts?

11
Jul

Finding the ratio: Why do we rest during workouts?

Source: CrossFit SOFLA

We train a good number of athletes that have passion for other sports besides CrossFit. We train runners, swimmers, road bikers, mountain bikers, soccer players, surfers, tennis players, and more, all of whom are training outside of the CrossFit gym. Most of these athletes do not have a home gym equipped with lots of equipment, so many times they concentrate on cardiovascular/respiratory endurance. When you train alone and design your own programming without the help of a coach, it is necessary to understand how the body works in order to gauge what you will program and how you will deal with work-to-rest ratios. Working on your cardio outside of the gym is awesome, but doing it haphazardly and without a plan will just be a waste of your time. Once you program what you’d like to do (run, swim, bike, etc.) you’ll need to know how to time your rest. Let’s take a look at how to decide upon work-to-rest ratios for your personal programming.

Some science first…

There are three systems that we can draw on to produce the energy necessary to do exercise/physical work: the phosphagen, glycolytic, and oxidative systems.

In order to fuel contraction, a muscle must produce a chemical called ATP. A small amount of ATP already exists in the muscle, but the rest must be synthesized from other fuel sources in the body such as protein, fat, glucose, or creatine phosphate stores. The chemical processes that produce the ATP from these different fuel sources are different; some require oxygen while others do not. Let’s take a quick look at these three different systems separately so we can clearly distinguish one from the other:

The Phosphagen System

  • Fuels the highest power output (4x the power of the oxidative system)
  • Has limited fuel available
  • Can provide peak power for approximately 11.5 seconds only
  • Predominantly used during high power outputs for 0-10 seconds

The Glycolytic System

  • Is the second fastest way to re-synthesize ATP (phosphagen is the first)
  • Has limited fuel available, but more fuel than the phosphagen system
  • Can provide high power for approximately 30 to 60 seconds

The Oxidative System

  • Is the slowest way to re-synthesize ATP
  • Has an abundant amount of fuel, but is released slowly
  • Can provide low power energy for very long periods of time

In addition to having an understanding of the energy systems, it is necessary to understand the basics of muscle fibers if you are going to properly program for yourself. Let’s break down the three types of muscle fibers:

Type 2b Fast Twitch Fibers

  • Are recruited for very short duration, high intensity bursts of power such as a maximal lift or all-out sprint
  • Produce high force levels quickly
  • Fatigue quickly

Type 2a Fast Twitch Fibers

  • Are recruited in sustained power activities like a 400 meter sprint or repeatedly doing lifts below your maximum (but not light weight)
  • Produce high force levels quickly, but not as quickly as type 2b fibers
  • Do not fatigue as quickly as type 2b fibers

Type 1 Slow Twitch Fibers

  • Are recruited in lower intensity exercises like light resistance work or long aerobic activities such as running a 10k
  • Do not produce high levels of force
  • Do not fatigue quickly

Ok…Now that we have some basics on how the systems work and how the muscle fibers function, let’s talk about work-to-rest ratios.

A lot of what we do in our training is nestled right in between the phosphagen and glycolytic systems. We use a combination of both of those systems during many of our CrossFit WODs, and hopefully, our athletes are tapping into those systems when they train outside of the gym. When you use these high-power systems, your body will require a decent amount of rest time between your intervals in order to stay at that high-power level. Why do you need this rest time? Well, you need the rest time because when you perform at such a high level of power, a considerable amount of lactic acid accumulates in the primary muscles involved in the exercise. If you do too much too soon, not enough of the lactic acid will have been cleared from the muscles. If the accumulation of that lactic acid gets to be too high, what comes next is major muscle fatigue and big loss of power, which will obviously affect your performance.

So now we know why we need to rest, but how long should be resting? Take a look at the chart below to see what your work-to-rest ratios should look like:

What this chart is saying is that your work-to-rest ratio depends on the amount of power you are putting out. If you are going short and fast, you need longer recovery time. If you are going long and slow, you need shorter recovery. Here’s an example:

You decide you are going to do 4x 400 meter repeats. You can personally run a hard and fast 400 meter at 2 minutes. What that means is that you will need anywhere from a 1:2 work-to-rest ratio to a 1:4 work-to-rest ratio depending on your body. So if you want to consistently hit 2 minutes every time, you’ll need to rest anywhere between 4 and 8 minutes between each 400 meter sprint. This will ensure that you get the amount of rest you need in order to perform at your peak power. And by the way, during that rest time, you should not be sitting or lying down; you need to be jogging lightly or walking. The active recovery will maintain blood flow to and from your muscles, which will contribute to the removal of lactic acid. Keep in mind that if you are recovering from work that primarily uses the phosphagen or oxidative systems, you can simply rest, as you do not produce very much (if any) lactic acid. PS: As you become a better athlete, your goal would be to aim for less and less rest. So, for instance, you may start by needing a 1:20 ratio (phosphagen system), but as you become fitter you’ll want to bring that ratio down closer to 1:12.

So, folks, the idea here is to make a plan. Decide what you are going to do and come up with your work-to-rest ratios to make the most out of your training. Avoid going for a run and instead, for example, do 10 x 100 meter repeats with a 1:3 work-to-rest ratio. You’ll get a whole hell of a lot more out of it. Happy training!

Internet Sources:

http://library.crossfit.com/free/pdf/56_07_Rest_Recovery.pdf

http://www.crossfit.com/journal/library/10_03_metab_cond.pdf

http://www.ideafit.com/fitness-library/the-three-metabolic-energy-systems