Obstructive sleep apnea and central sleep apnea are burgeoning sleep-related breathing disorders within the general population. Most of the associated comorbidities and causes of these sleep disorders are known to negatively impact cardiorespiratory fitness; however, little is known about the direct relationships between cardiorespiratory fitness, obstructive sleep apnea and central sleep apnea. This article provides a systematic analysis of existing peer reviewed, published clinical studies pertaining to the relationship between cardiorespiratory fitness and sleep-related breathing disorders in adults.