The primary rationale of those challenging the need for higher volumes is that many studies on the topic have failed to show statistically significant differences in hypertrophy between conditions. Indeed, when observing the individual studies that compare single-set training with multiple-set training, we sometimes see no statistically significant differences between the training conditions. For example, Mitchell et al. (22) compared two groups of 18 untrained men, of which one performed 3 sets of knee extensions per training session, while theother performed only 1 set per training session. Following the intervention, no significant between-group differences were noted; however, the group that trained with 3 sets increased thigh cross-sectional area by 6.8% while the 1-set group increased thigh cross-sectional area by 3.1%. Despite an inability to detect statistically significant findings, the effect size difference of 0.27 favoring the higher volume condition indicates results were potentially meaningful from a practical perspective. Similar findings have been reported in resistance trained men. In the seminal work by Ostrowski et al. (26), 3 groups were compared with subjects randomized to perform either 1, 2 or 4 sets per exercise. Muscle cross-sectional area data for the quadriceps muscle showed a 6.3%, 4.6% and 12.3% increase in size for the 1, 2, and 4 sets per exercise groups, respectively. Although findings did not reach statistical significance, the effect size difference of 0.29 between the highest and lowest volume conditions again suggests a hypertrophic benefit for greater training volumes.