Training studies are dependent on several factors, including the frequency, intensity, and duration of the training sessions and the training program. In addition, the baseline value is also important to consider. For example, one review of the literature for VO2max indicates an average net increase of 8.6% and a range in the mean response from 1% to 29% (Pfeiffer et al., 2008). Thus, some youth respond to training whereas others do not respond.