In a nutshell, aerobic exercise is any activity that uses up oxygen and anaerobic exercise is reached when we just cannot supply enough oxygen to the system to meet the demands of the output we are trying to maintain.  So we are primarily aerobic much of the time until we increase our output to the degree that we require more oxygen then we can provide given the current level of conditioning and physical limits of our body.  When we perform in an anaerobic environment our breathing rate dramatically increases, we begin to feel the increased lactic acid, or “the burn”, in our muscles, and very frequently our bio-mechanics (form) during exercise rapidly deteriorates until we either finish the event or become incapable of maintaining the increased output and we slow or discontinue performance altogether. 

You might be asking yourself, “Why should we care whether we are aerobic or anaerobic. Isn’t any exercise good for me?”  While there are countless responses to this question, I will sum it up by saying that raising your anaerobic threshold is simply going to make your life easier, more efficient, and less stressful. 

The obvious question that remains is: How do I increase my anaerobic threshold?  The high point of this whole article is that developing a higher anaerobic threshold is often easier than the cardio program we are used to.  Begin with several weeks of training near but below your current anaerobic threshold.  This will train your body to be more efficient at the aerobic level and typically will begin to elevate your anaerobic threshold at the same time.  If you do not know what your current threshold is then utilize 180-age=BPM and use that figure as your heart rate during cardio vascular exercise for 4-6 weeks.  This is a rough figure but helpful for this type of training.  For most of us, this output level is much lower than we are capable of and that is the point.  If you are training primarily above your anaerobic threshold, it will slow your athletic progress after a time due to the chemical stress of training at that level.  You will progress faster by training for some time at a lower heart rate and sporadically utilizing sprint or lactate threshold training.  This is like cross training for your cardio and I think we all agree that cross training creates a better athlete and a stronger more capable body. 

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Our bodies use (ATP) adenosine Tri-phosphate as its main source of energy production.  The primary reason for taking a break in between sets is to allow time for the replenishment of ATP levels.  The amount of time we take between sets depends on the objective of the set or training program.  Taking a break for 45-60 seconds allows approximately 75% of our ATP levels to be replenished.