In an earlier post, I talked about how Dextrose can maximize the use of the body’s glycolytic energy system (aka, how it burns carbs), allowing us to preserve muscle mass through contest prep while giving us a little more lifting power during the off season.
Interesting stuff? Absolutely. Is that the end of the story on how we can tap into biology to benefit our gains?
( prepare yourself, more geeky science stuff 😀 )….
ATP-PCr: The Incredible Hulk of Energy Systems
Our bodies are fueled by something called “ATP” (adenosine triphosphate). ATP is to us like fuel is to our car. It can’t run without it.
However, we don’t store a whole lot of ready-made ATP. Our bodies pretty much make it as we go along. We do this through three different energy systems. These energy systems can be working at the same time, but each one uses a completely different process – some quick, others more complex – to create ATP. Determining which energy system takes precedence over the others depends on what exercise you are doing and how significant your energy demands are.
ATP-PCr in the muscle is the fastest at creating ATP and also the most powerful of all three of our energy systems. And when I say powerful, I mean explosive powerful. Sprinting off the blocks powerful. I just pounded out a 250lb deadlift powerful.
It’s the one we want dominating over the rest on our quest for muscle growth.
- ATP = Energy
- The body readily makes ATP. There is not a lot of ATP storage.
- To optimize muscle growth, performance and power we want the ATP-PCr system in the muscle to dominate as the source of energy (ATP).
How the ATP-PCr Energy System Works
Because the ATP-PCr in the energy system can create ATP so quickly, it kicks in immediately when we begin to workout. Regardless of what exercise you are doing, this energy system is going to be the first one you access. As a bodybuilder, it’s the one you want to use more than the rest.
Let me boil it down into a very basic and yet completely scientific explanation: We have what’s known as “phosphocreatine” stored in our muscles. Phosphocreatine is sort of the Brangelina of the ATP-PCr system. It begins as a marriage between creatine molecules and phosphate molecules. Together, these two are the power couple we call phosphocreatine. However, when energy is needed, the body breaks this partnership apart (so each one – phosphate and creatine – go their separate ways, hopefully amicably), which results in the creation of ATP.
Unfortunately, we don’t store a whole lot of phosphocreatine in the body. This means that we can’t rely on the ATP-PCr system for long; we have only about 8-15 seconds before it runs out.
So that’s 8-15 seconds of super explosive energy. Not a whole lot, but when we’re talking squats, it can actually contribute to a good amount of power through each set.
The more we can use the ATP-PCr system, the more explosive energy and strength we will have. The more strength and intensity we use to lift, the more damage (hypertrophy) to the muscle occurs.
And hypertrophy is what leads to increased muscle growth.
- ATP-PCr kicks in quickly and creates ATP (energy) quickly.
- It’s the first energy system to provide energy but also very short lived (8-15 seconds) because it runs out of the limited supply of phosphocreatine.
- The more we can use the ATP-PCr system, the harder we can lift and make gains!
Why Timed Rest Between Sets Matters for Muscle Growth
While the ATP-PCr system powers intense movement for only 8-15 seconds, there is good news. It can regenerate itself fairly quickly.
What this means for you is that the ATP-PCr system doesn’t have to be limited only to the first 8-15 seconds of your workout. It can actually be available for the first 8-15 seconds of each of your sets – over and over again.
By timing your rest periods.
Let me explain.
Whenever we do intense exercise – such as resistance training or HIIT – we are performing an “anaerobic” activity. This means that the activity requires more oxygen than our bodies are able to take in at that moment.
Luckily, we have two energy systems that don’t require oxygen in order for them to work.
One of them is the ATP-PCr system, which is heavily relied upon during anaerobic (intense) exercise.
However, anaerobic activity usually leads to a phenomenon known as “EPOC,” which stands for “Excessive Post-Exercise Oxygen Consumption.” What this means is that during an intense activity, we needed more oxygen than we actually had available. This creates what’s called an “oxygen debt.”
Like financial lenders everywhere, the body is a selfish bugger, so it demands that we pay the oxygen debt back before it allows us to perform intensely again. It’s at this point that the body will slow down during an activity, causing the energy systems to downshift to one that allows us to catch up on our oxygen consumption.
Think of it this way: You are pushing through a set of heavy-ass squats. With each repetition you take a deep breath, then exhale while pushing the weight up. All you notice at that moment is completing the rep before your legs give out, which of course you do because you rock. After finishing the set, you find yourself breathing heavy like you just ran a freakin’ race.
This is your body paying back the oxygen debt.
You know the oxygen debt is in the process of being paid back once you return to a normal breathing pattern.
Once the body starts to catch up oxygen, the ATP-PCr energy system begins to restore itself.
While the timing of ATP-PCr resynthesis is dependent upon the intensity of the activity, how significant of an oxygen debt was incurred, and how conditioned the body is in the first place, the consensus seems to be that it takes around two minutes for the body to regenerate phosphocreatine stores while strength training.
That means if you rest for two minutes between sets, your body has an opportunity to use the ATP-PCr energy system again. And again. And again.
If you weren’t timing your sets before, now is the time to start.
Whether using your phone, Fitbit, or other timer, set it for two to three minutes and start it up every time you finish a set. Don’t try to wing it when it comes to rest between sets; it’s easy to think two minutes have gone by when you’re pacing around looking angry or switching plates. I want you to actually time it. You might be surprised how long it feels.
Do it. It makes a difference.
- ATP-PCr system is the first to kick in, runs out quickly but it also regenerates quickly!
- This energy system is available for the first 8-15 seconds of every one of your sets!
- So time your rest periods.
- How? Once this system runs out of energy, your body needs more oxygen and you start breathing heavy. Once you rest and your breathing slows, (about 2 minutes or so) the ATP-PCr system is ready to get back into action.
A Word About Creatine and ATP-PCr
Some of you may not have missed that I’ve mentioned creatine like a hundred times in this post. Unless you are new to the sport of strength training or living under a rock, you likely know that one of the most popular bodybuilding supplements available is creatine monohydrate. You may be wondering, is there a connection?
Why yes there is!
Creatine is, in fact, one of the two most essential molecules in phosphocreatine. It’s the Brad in Brangelina.
So how does it benefit the ATP-PCr energy system?
While our bodies naturally make creatine from amino acids as well as from the meat we eat, an overwhelming amount of studies have shown that ingesting supplemental creatine increases overall uptake into the muscle.
However, we can only store and use so much creatine at a time, and exactly how much depends on who you are. People who are more active and have large amounts of muscle mass typically benefit from additional creatine than a less-active individual. However, the general guideline is that 3-5g of creatine supplementation per day is sufficient (too much and our bodies excrete the extra in our urine).
Why is this important?
Because the more creatine we store, the more phosphocreatine becomes available. The more phosphocreatine we can use, the more ATP we can make through the ATP-PCr energy system.
Remember, the more we can push the ATP-PCr energy system to be the dominating force behind our workouts means more explosive power with each repetition.
And explosive power means greater muscular gains.
- Creatine Rocks. Take it.
- Because the more creatine we store, the more phosphocreatine becomes available for the ATP-PCr energy system. Boom. Beast mode.
Bodybuilding Really Is a Science
People may be skeptical when I suggest that bodybuilding is a science, but there truly is a method to the madness. Through careful manipulation of the nutrients we eat, the maximum weight we lift, the kinds of supplements we use, and even the amount of rest we take in and out of the gym can all influence how we look, feel, and progress. If we can understand the complex mechanics of our bodies, it’s easier to get behind strategies that just might work.
Plus, knowing this information makes you feel totally bad ass at dinner parties. Though you may lose a little credibility if you refer to phosphocreatine as Brangelina.
Rest about 2 minutes between sets to make each set COUNT for optimal muscle growth, power and performance and take creatine. Boom. Now hit the gym.
If you find this post fascinating, I encourage you to explore my blog where you can find information not only on the science behind certain workout strategies, but also topics relating to nutrition, women’s health, and contest prep.
I also invite you to join the GF2 Fitness and Contest Prep Forum on Facebook. Here you can ask questions, get inspiration, and receive positive support from people just like you.