Moreover, participating in a co-ed martial arts class may have affected the girls differently than the
boys, perhaps causing them to be less zealous in their participation. In their meta-analysis of adventure education programs, Hattie et al. (1997) noted that single-gender groups had greater mean effect sizes than co-ed groups. Because the majority of the single-gender groups were Australian groups, who had higher effect sizes overall, the effects were confounded. The authors reported that they were unable to contrast the effects from male and female participants crossed with single-gender and co-ed programs because the data were not available. Hattie et al.’s findings support the assertion that the co-ed nature of the LEAD classes may have impacted the gains received by girls, and further research is needed to contrast the effects of single-gender and co-ed martial arts classes on girls.
Therefore, we believe that it is premature to conclude that LEAD is inherently less effective for
girls than it is for boys. Each of the possible explanations for the gender differences is plausible. It is clear that more research is needed to address the effects of martial arts interventions by gender. In a
1997 report by the President’s Council on Physical Fitness and Sport (1997), the importance of physical exercise for the physical and mental health of girls was emphasized and it was recommended that girls should be encouraged to participate in physical activities and sports at an early age. Future studies should be conducted to test the hypotheses we have discussed; for example, future studies could compare outcomes from co-ed martial arts interventions to same gender interventions or could examine outcomes of interventions that match the gender of the instructor to the gender of the students.
4.3. Developmental effects
Post hoc analyses suggested that there might be differential gains in affective self-regulation based on a child’s developmental level, or age. Gains for participants in kindergarten/first grade were small, suggesting either that that these children did not experience the benefits of intervention to the same degree, or that there are developmental processes involved that limit the degree to which they might benefit from this particular intervention. Children appeared to benefit more at older ages, with moderate gains by second and third graders and large gains by fourth and fifth graders. These results suggest that LEAD had an impressive impact on affective self-regulation in fourth and fifth graders, with a smaller impact on younger children. The trend toward greater gains in older children was present for cognitive and physical self-regulation as well, although the interaction was not significant. However, these results must be considered cautiously, as the analyses were conducted post hoc. To further investigate intervention impact on gains in self-regulation by developmental level, future researchers should include age or developmental level in their hypotheses. Future studies should clarify at what age students begin to profit from the more structured discipline of martial arts training, as compared with
the less structured, but presumably equally physically active setting of a conventional physical education class.