Evolution of the total mass of ¹⁴N inside the rapidly rotating stellar models during their evolution. For the 20 M_⊙ model (orange), the non-rotating and moderately rotating models are also indicated by dotted and dashed curves. On the x-axis the fraction of burning phases is given, where the core H-burning phase is for 0–1, the core He-burning phase is for 1–2, and the advanced burning phases are for 2–3. The non-rotating and moderately rotating models were taken from Murphy et al. (2021a).