This dataset contains anonymized cardiopulmonary exercise test data collected from trained youth male soccer players during a progressive cycling time-to-exhaustion protocol. Time-based measurements of oxygen uptake (VO₂), carbon dioxide production (VCO₂), minute ventilation (VE), oxygen saturation (SpO₂), heart rate (HR), and heart rate reserve (HRR) were recorded alongside biological maturity indicators expressed as maturity offset. The data were used to examine maturity-related differences in cardiopulmonary responses across relative exercise duration, as reported in the associated manuscript.