Men and women differ in anatomy and physiology resulting in marked sex differences in neuromuscular performance and fatigability of skeletal muscle. Muscle fatigability is an acute activity-induced reduction of force or power of a muscle: it is typically quantified as the relative reduction in maximal strength and power, and the time to failure of a submaximal task (Gandevia, 2001). Multiple mechanisms are responsible for fatigability in men and women and may include activation of the motoneurone pool from cortical and subcortical regions, synaptic inputs to the motor neuron pool via activation of metabolically-sensitive small afferent fibers in the muscle, muscle perfusion, skeletal muscle metabolism and altered crossbridge dynamics in the muscle fibers. The mechanisms of fatigability are specific to the details of the task because different neuromuscular sites will be stressed when the requirements of the task are altered (Enoka & Duchateau, 2008). There are sex differences in muscle fatigability which are specific to the requirements of the task. This means that the magnitude of the sex difference in fatigability and the contributing mechanisms to this difference can alter as the task varies (Hunter, 2014). Typically, studies show that for upper and lower limb muscles, women are usually less fatigable than men for similar intensity isometric fatiguing contractions due contractile mechanisms and muscle perfusion. Less is known however, about the sex differences in fatigability of dynamic contractions and the responsible mechanisms. Data from my laboratory supports findings that for slow-to-moderate velocity contractions, women are less fatigable than men (Hunter, 2014). However, this sex difference in fatigability of dynamic contractions varies with the type of dynamic contraction (shortening or lengthening), intensity and speed of the contraction and the muscle group assessed. For muscle shortening tasks, when men and women were asked to contract as quickly as possible with a load at 20% of maximum, the decline in power for both the elbow flexor and knee extensor muscles was similar for men and women. However, the reduction in maximum voluntary isometric force (MVIC) measured immediately after the dynamic contraction was greater for men than women but only for the knee extensor muscles (Senefeld et al., 2013). Additional experiments using transcranial magnetic stimulation, showed that supraspinal fatigue (fatigue from inadequate activation of the motor cortex) increased but was similar for men and women after the dynamic fatiguing contraction. Rather, contractile properties measured from electrically evoked contractions, slowed more dramatically for men than women. Hence, the contractile mechanisms were responsible for a sex difference in fatigability after the dynamic contraction when assessed with a MVIC. These findings are consistent with muscle biopsy studies that indicate the whole skeletal muscles of women possess a greater proportional area of oxidative and fatigue resistant fibers than men (Hunter, 2014). Furthermore, these studies highlight a task specific interaction between the type of fatiguing task and the maximal strength measurements typically utilized to quantify sex-based differences in fatigability. In contrast to shortening contractions, the sex difference in fatigability for lengthening contractions may be reversed because women appear to experience greater fatigability within the muscle than men (Power et al., 2013). More studies are needed because our understanding of sex differences in response to lengthening contractions is very limited, despite their importance to daily tasks, training and rehabilitation. Finally, non-physiological factors contribute to a devoid understanding of sex-based differences in muscle fatigability. There is a historical and current sex bias of studying more males than females in human and animal experiments in both physiology and fatigability (Beery & Zucker, 2011). There is also the false assumption that men and women respond similarly to fatiguing exercise. The field is ripe with opportunities. Knowledge of the underlying mechanisms of sex-based differences in fatigability during the different types of dynamic contractions will clarify the benefits and limitations that skeletal muscle fatigability can exert during daily tasks, exercise performance, and training in both men and women.