Aerobic vs Anaerobic Metabolism: Fuel Use During Exercise

Added: 2026-05-18

[00:00:07]in this video I want to talk a little bit about aerobic versus anerobic activities and what types of fuels we use for each of these so recall from chapter 3 that aerobic activities are those activities where we have an the activities not too intense and we can adequately Supply our body with the right amounts of oxygens it needs it so about like walking sitting going for a run at a reasonable Pace at a moderate Pace your body knows how to match fuel uh needs with fuel delivery okay Anor robic activities are those activities that are very high intensity or also those activities really at the beginning of exercise when your body hasn't figured out where to deliver uh oxygen at the correct levels okay so just to recall again actually I'll start with anerobic anerobic technically means without oxygen but that doesn't mean you're not breathing you're still taking oxygen into the body it's just that you don't have enough at the particular cells that need that oxygen usually because again it's at a high intensity or it's right at the beginning of workouts okay so these are typically high intensity activities or the beginning beginning of activity okay so uh with Anor robic activities the main type of fuel that we use pretty much the only fuel that we use is glucose okay so um you'll recall that glucose C6 h 126 can be broken down into pyruvate which if there's no Oxygen available or not enough oxygen available this is used to make something called lactate and we produce some ATP in the process okay so this really is the only fuel like dietary fuel that our body can use for Anor robic activities in the beginnings of exercise like the like the first few seconds kind of gone right away we can also use up a little bit of ATP that's already there around the tissues and something called our creatine phosphate ATP pathway but this really gets used up within seconds and for very high intensity activities we're using glucose as our main fuel source or kind of in the first 2 to 20 minutes of exercise once this has really been used up and our body is still getting getting used to that type of exercise glucose is uh the main fuel that we tend to use okay and I'll contrast that with aerobic activities okay so aerobic activities mean with oxygen which means that they're kind of steady moderate activities they're not too high intensity and our body knows how to match needs with actual delivery okay so these tend to be moderate intensity activities or just like sitting so you're in your aerobic zone right now I'm in my aerobic zone right now because I'm not doing anything at too high of an intensity for aerobic activities recall that the main equation that happens is going to be C6 h126 or glucose in this case although we can use fatty acids and proteins as well plus oxygen six oxygen and that is going to produce water uh carbon dioxide and ATP and a lot more ATP and we can consistently make a lot of ATP when we have enough oxygen available okay and the equation would uh switch around slightly but I could also use um uh fats for this process and I can also use proteins or I should say amino acids but I'll just write protein prot here for this process as well okay however our body prefers for aerobic activities to use these types of fuels okay uh glucose and fats proteins aren't really a source of fuel for physical activity a really small percentage of the fuel we use to fuel our body's needs come from proteins the majority of our fuel sources that fuel our typical needs which are typically aob come from either glucose I'll just write glucose in here or fats okay so let's put this in context if you are let's say a longdistance runner or you are doing activities it doesn't even have to be a long-distance Runner but if you're doing activities kind of more than half an hour you're at a moderate Pace you don't have any really high intensity activities you are mainly burning glucose and fats whereas if you're like Sprinter or you're doing like weightlifting really high-intensity activities you are mainly using glucose for energy okay and you can only do those for so long cuz remember this builds up this product that can be really painful to the muscles and the body okay so that hopefully gives you an understanding of what we mean by anerobic metabolism and what we mean by aerobic metabolism and the types of fuels that are used for each of these types of processes