Fig. 4
Mixed-effects meta-regression of the changes in Intraclass Correlation Coefficient (ICC) while controlling for the effects of mean age (A); SMFT exercise intensity (HRex) (B); SMFT duration (C); age category (senior vs. youth) (D); and HRex collection method (fixed vs. mean range vs. mean overall) (E). Data points represent individual effect estimates included in our meta-analysis, and the size of the data point is proportional to their weighting. Green, red, blue and purple points represent studies using continuous fixed, intermittent incremental, intermittent variable small-sided games, and intermittent variable passing drills category, respectively. Solid lines represent the estimate of the modifying effect. Dashed and dotted lines represent 95% confidence and prediction limits, respectively. HRex exercise heart rate, y years, min minutes