One of the most striking findings from lowvolume HIIT studies is the dramatic improvement in exercise capacity during tasks that rely mainly on aerobic energy metabolism, despite the relatively small amount of total exercise training performed (Burgomaster et al., 2005; Gibala et al., 2006; Little et al., 2010). For example, Burgomaster et al. (2005) found that subjects doubled the length of time that exercise could be maintained at a fixed submaximal workload — from ~26 to 51 min during cycling at 80% of pretraining VO2peak — after only six sessions of Wingatebased HIIT over 2 wk (Figure 2).