Whether you are an elite, a top age grouper or a back of the packer everyone wants to improve their performance. An improvement in performance can be defined as winning to just feeling better and finishing upright and smiling. To facilitate this improvement you have to identify which system; cardio, muscular or respiratory limits your performance (limiter) and when your limiter becomes exhausted which system compensates (compensator). To determine this we perform an assessment using the Moxy Monitor. The Moxy Monitor assessment as it pertains to running and triathlon is a progressive treadmill, bike trainer or swimming test where a load is applied for five minutes then taken away completely for a minute then applied again for five minutes then increased for multiple 11 minute loads until the information required is derived. The body is accessed by observing how the body handles this constant challenge to homeostasis by observing blood flow and oxygen consumption at the cellular level which is important from the perspective of how the body makes energy while active. Speaking in terms of training zones, zone one is easy warm-up or recovery pace where your limiter is not even touched. Zone 2 is endurance pace where you can work for a long time, anything over 2.5 hours and your limiter is capable of keeping up with the load. Zone 3 is anything that takes less than 2.5 hours and is that speed at the low end where your limiter is beginning to be stressed and at the high end it has fatigued enough that your compensator takes over. In zone 4 your limiter is done and your compensator has taken over completely. It is not likely you can work here for very long. A cardio limitation is common in newbies and those that have been away from sport for a while. Simply it is a lack of ability to get enough oxygenated blood out to the muscles to use; essentially there are more workers available (mitochondria) than work (oxygenated blood). It is easy to improve this limitation through consistent easy running and/or HIIT intervals. A muscular limitation is when there is not enough mitochondrial density to allow you to train or compete faster and longer. Mitochondria are the power sources of cells where oxygen dependent respiration occurs. Endurance training, HIIT and/or weight training are the essential workouts to improve mitochondrial density. A respiratory limitation is most common with experienced athletes and is the most complicated/involved of the limiters. It could be as simple as a weak diaphragm, too much carbon dioxide in your blood or too much oxygen all of which can be improved by learning to breathe diaphragmatically. Sometimes it is a utilization issue where you can get all the oxygenated blood to the mitochondria and enough mitochondria to use the oxygen to make energy but you just can't use it which means you can't use fat as an energy source. HIIT workouts help with this issue.