The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders.

The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %.