Burn (efficiently) baby, burn.
Your body is one energy burning machine. That is, when you fuel it properly. But this blog isn't about how to fuel properly, it's about how your body breaks down fuel to be used as workout crushing energy. Why should you care about how your body gets the job done? Because it's freakin' cool, that's why! So, stick with me. It all begins with Adenosine Triphosphate, but to its friends, it's known as ATP. It is the high-energy molecule that stores the energy we need to do, basically, everything. Do me a favour and wave your hands in the air like you just don't care. Congratulations, you've used ATP and probably looked a little silly. Still with me? Good, let's jump into the fun stuff. (psst, you can put your arms down now) Say you're doing a heavy squat, the first system to fire into gear is called our Anaerobic System and it kicks things off by using whatever ATP is floating around in our muscles, giving us around 3 seconds of energy. I can think of a few things that only last 3 seconds, but none of them are my workouts! Luckily, our muscle cells contain creatine phosphate which works damn quick at replenishing our ATP so we can keep crushing it! Thanks, creatine! However, because creatine levels decrease quickly, you will only get around 8 - 10 more seconds of sweet, sweet energy. Right about now you are probably wondering why you don't collapse after 10 measly seconds of training. That's because your body is an energy converting machine.
Before you even hit the gym floor, your muscles & liver have taken complex carbohydrates from past meals and stored them as glycogen (also stored in the blood as glucose). So, once you're outa ATP, your body will switch into the Glycolysis System, working like mad to convert glycogen from our muscles and liver (or blood glucose) into more ATP. Nothing comes for free, though, and this process also produces a by-product called lactic acid. Otherwise known as "Ow, f*ck, slow down, it hurts, the pain!" Don't worry, as we progress in our training our bodies become better at dealing with big bad lactic acid. The Glycolysis System burns slower than the Anaerobic System and it'll give you a whopping 60 - 90 seconds of killer energy! Though that might not sound like much, it's enough time to get you through a set before you take a break. After this, if you're doing any sort of sustained activity, you'll get bumped into the Aerobic System. This is where a pre-workout meal comes into play. The Aerobic System will go digging for any glycogen left in your liver or muscles, but will also take glucose absorbed from the food you have digesting in your intestines and breaks it down to become ATP. Because we usually have food from our pre-workout eats or from our dinner the night before kicking about in our system, the Aerobic System can sustain us for well over an hour before we may need a mid-workout boost. That'll depend on how you've pre-fuelled and your own personal metabolism. The double cool thing? Our Aerobic System can burn fat for ATP. But be careful, because in extreme situations (like starvation) it'll also go after muscle building protein. I'll touch more on how you can access fat for energy and avoid burning protein in another blog post. Oooh, cliff-hanger! Can you handle the suspense?! Of course you can because you're a machine. Also, yay you for making it to the end. You get a (protein) cookie.