Fig. 1

Schematic of data treatment to extrapolate the rates of change in fatness and fitness across Grade 4, Grade 5 and the holiday period. Outcomes (here, estimated VO_2max) were measured at the start (T1) and end (T2) of Grade 4, and at the start (T4) and end (T5) of Grade 5. Values were then forward- (Grade 4) or back-extrapolated (Grade 5) to estimate the values at the start and end of the holidays. Rates of change between timepoints, indicated by the slopes of the segments, were derived by dividing the calculated change by the number of intervening days, and then annualised. ∆T1-start = rate of change from T1 to start of holidays; ∆Start-End = rate of change from start to end of holidays; ∆End-T5 = rate of change from end of holidays to T5