Breathing before and after exercise

        Think about when you first start running.

It feels great

Feel like you could run forever

Fast forward to the end

It feels like you want to throw up

Ever wonder why?

    Several factors really. Could be how aerobically trained you are, intensity of workout, weather conditions. The aspects that we will investigate within the post are Oxygen deficit and Oxygen debt.

    When you start running (or any other aerobic style training. Swimming, cycling and rowing will also work here) your anaerobic system provides the initial energy levels as the aerobic system catches up. Think of the aerobic system as a turbo in a vehicle. It takes time for the turbo to catch up (turbo lag), but once it kicks in it provides more power to the vehicle. Once the aerobic system catches up the oxidative system provides more of the energy source through the Krebs cycle. For full clarity the oxidative system yields 38 ATP (Well it produces 40 ATP, but it cost 2 ATP for the system to run).

    The initial push of the anaerobic system is called Oxygen Deficit. Think of it this way when there is a deficit of something we use something else as a replacement. In this case our oxidative system hasn't caught up yet, so the anaerobic system kicks in due to the deficit. Once the oxidative system kicks in it depends on the intensity of the training on when or if Oxygen debt occurs. I say if because if the intensity of training isn't high enough to break the Vo2 max threshold then your body can maintain oxygen levels while training. This isn't a dig either. For example, long, slow distance style aerobic training is at a lower enough intensity where oxygen debt does not occur. Exercising over the Vo2 max threshold does trigger oxygen debt or excess postexercise oxygen consumption (EPOC). A good metaphor is that your body owes your oxygen...hence debt. That is the part after the run where you feel like you're about to throw up. It is the body playing catch up oxygen wise. The length of intensity determines EPOC time. Lower intensity has shorter EPOC time period, more intense exercise has a longer EPOC time frame. Those long, intense runs that suck the life out of you? Those are going to require a longer EPOC time period. During EPOC the body replenishes oxygen in blood and muscles, resynthesis of ATP/CP (energy systems) and overall recovery of the body.

    EPOC or oxygen debt does not only apply strictly to aerobic training. It can apply to resistance training as well. In fact, heavy resistance training produces more oxygen debt than circuit training. Heavy resistance training entails 3 sets to exhaustion to 80%-90% of 1RM. That in itself is a very challenging workout. For full disclosure circuit training for this study is four sets of 15 reps at 50% RM. This means that EPOC is dependent on intensity levels regardless of training style.