To guide action to the research procedures and to achieve its objectives, the researcher assumed the following:
 There are statistically significant differences between the average of the pre and post measurements in some (physical - physiological - bone mineral density) variables in favor of the post measurement.
 There are statistically significant differences between the average of the pre and the post measurement in the level of performance of athletics competitions among 11-12 year kids' under study in favor of the post measurement.
 There are change ratios in some (physical - physiological - bone mineral density) variables and the level of performance of some athletics competitions among 11-12 year kids 'in favor of the post measurement.
 There are change ratios in the level of performance of athletics competitions among 11-12 year kids' under study in favor of the post measurement.