To make muscle, you need, among other things:
1) the energy to workout
2) the energy to build muscle
For the human body (and I would bet for most animals) the energy-source for the body is something called ATP. The body builds ATP just to tear it down (kinda like an ex-girlfriend of mine did with me). When ATP breaksdown it releases energy, while simultaneously creating a sub-form of itself which can be easily (for the amazing human body) built back up to more ATP to produce MORE energy and keep the cycle going.
The problem a weightlifter will face when it comes to ATP, is that the body doesn’t actually store that much of it. In the entire body, there’s only about three ounces of ATP at any given time. But less than half of that is available for a workout (the rest being used for normal body functions).
A hard workout will quickly run through the available supply of ATP, and though more is being made all the time, the balance may not necessarily be in your favor. The good news is that, as our authors tell us, “repeated bouts of intermittent high-intensity contractions” (such as weightlifting) signal the body that, yo, this is the way things are going be, so get used to it… in other words, we’re gonna need more ATP storage. And the body dutifully acquiesces.
As far as new ATP for muscle building, the body makes more in two main ways (though the details are complex). ATP can be made in the Mitochondria (this way needs a lot of Oxygen to work) or it can be made directly in the sarcoplasm of the muscle cell.
The Mitochondrial way can produce a long-lasting supply of energy, but it’s rather slow and cumbersome (again, this all relative to the amazing processes of the human body), requiring long chains of reactions taking place in molecular assembly lines with names like the “Electron Transport Chain” and the “Krebs Cycle.” As our authors tell us, what all Mitochondrial energy-production chains have in common is that they all require an Oxygen molecule at the end of the chain to absorb the leftover electron inevitably produced during the energy production activity.
On the other hand, making energy directly in the sarcoplasm of the muscle cell does NOT require long chains of molecular reactions, nor is oxygen necessary (thus making this method “anaerobic” or “non-oxygenic”). Unfortunately, this simpler quicker type of ATP production is easily exhausted. Nevertheless, it is still perfect for weightlifting, which requires only bursts of energy ever few minutes.
In the muscle sarcoplasm method of making ATP, there are three star ingredients: 1) Creatine, 2) Blood Glucose, and 3) Muscle Fiber Glycogen.
The quickest ATP-production comes from using Creatine to make ATP from its precursor, ADP (the “D” in ADP stands for “Di-“, which means it’s one P [phosphate group] short of being ATP [the “TP” standing for “Tri-Phosphate”). Muscles store four to six times more Creatine than ATP, so in this way, Creatine is like an energy reserve– it can be used to quickly make more of the scarcer ATP.
Using either Blood Glucose or Muscle Fiber Glycogen for energy production is called Fast Glycolysis. This method produces energy faster than the Mitochondrial methods, and yet– because it requires several steps– it is slower than the Creatine method.
It is the Fast Glycolysis method which produces lactate, which most every athlete is familiar with, as it is associated with soreness. Scientists still aren’t sure how lactate relates to muscle fatigue– if it is more cause or effect. The current thinking goes like this… 1) strenuous exercise requires the burning the ATP for fuel, 2) the burning of ATP lowes the pH balance in muscles and blood by pumping out positively charged hydrogens, 3) lower pH (somehow) causes muscle fatigue.
However it is that lactate concentrations and lower body pH fit into the muscle fatigue picture, according our authors there is a direct and substantial correlation of both with the release of Growth Hormone — a very good thing if you’re trying to build muscle.
And lastly, in yet another example of the body’s adaptation to the stress of regular exercise… The bodies of habitual exercisers adapt so that more energy can be derived from the oxygen-dependent (aerobic) Mitochondrial methods, thus delaying the need to use the short-term, direct in-muscle sarcoplasm method which produces muscle fatigue and lactate build-up.