The Role of Rest In Your Workouts

Mariah May, CSCS

When exercising, it doesn’t always need to be a non stop hustle. Depending on your goals when training it can sometimes be necessary to take a break and recover during the workout. ATP is a form of energy that our cells use to do work; when you run out or is get low on ATP it can be produced in several different ways by the body. The depletion of ATP is part of the reason that rest can be so essential. 

The Energy Systems
There are 3 main energy systems our bodies use to provide energy. These energy systems are the phosphagen, glycolytic, and oxidative systems. The phosphagen system is for shorter extremely high intensity movements (0-6sec) and uses phosphagens (ATP and creatine phosphate) for energy. The glycolytic system is used for high/moderate intensities (30s to 2min) and uses glycogen stored in our muscles to make ATP. Lastly, the oxidative system for low intensity activities (3 mins and up) uses the carbohydrates and fats in our bodies to make ATP. The image below illustrates how the energy system we use changes depending on the intensity and duration of the exercise we are doing.  (PCr = Phosphagen)

All these different systems use up energy at different rates and require different amounts of rest to replenish ATP. Many of our work out blocks have exercises that fall into the phosphagen and glycolytic systems. As you go from phosagen to oxidative the intensity of the exercise decreases while the rate of ATP production increases. For example, if you did a set of heavy hang cleans, it is a very high intensity movement that is for a shorter period which means it requires the phosphagen system to get the ATP as quickly as possible. But since you used that ready to go ATP it takes awhile to get it restored. Let's switch to running 6 miles, that takes longer than 3 minutes which means our body starts getting its ATP from the oxidative system, which is very effective at collecting energy from the carbohydrates and fats in our bodies. Once you finish your run you would need way less time to get your energy back than you would those intense power movements, because the rate at which those energy systems make ATP are so different.

Rest Periods

What this means is that we need to be aware of the rest we are taking in our workouts to match our goals. If you try to blast through a 5x5 of heavy bench press with no rest you aren’t allowing your body time to recover ATP and work at your full potential. When doing interval work each energy system has a different recommendation for work to rest ratios.

Phosphagen system: 1:12- 1:20

Glycolytic: 1:3- 1:5

Oxidative: 1:1- 1:3

Next time you're doing a workout take the time to think about what system that movement or activity requires and see how much rest is recommended to get the full benefits. Just remember what your goals are and you may see an improvement in your gains just by adjusting your rest time!

Image:

https://canada.humankinetics.com/blogs/excerpt/energy-systems

Resource:

Haff, Greg, and N. Travis Triplett. Essentials of Strength Training and Conditioning. Fourth edition. Champaign, IL, Human Kinetics, 2016.