Run: slow base + weekly HIIT

Recent exercise physiology reviews note that maximal fat-oxidation (FATmax) typically occurs at low-to-moderate intensities—roughly 40–50% of VO2max—and that whole-body fat oxidation rates often rise over the first 20–30 minutes of steady exercise, supporting why sessions longer than 20–30 minutes shift substrate use toward lipids. (nature.com) (nature.com) Controlled trials tracking fat‑oxidation during interval sessions found peak rates emerging late in 30‑minute moderate sessions (minute ~25 in one study of sedentary participants), indicating duration as well as intensity drives fat use. (ksu.edu.sa) (faculty.ksu.edu.sa) The 20‑second work / 40‑second recovery split cited in the threads is a common 1:2 work‑to‑rest HIIT template used for beginner to intermediate sessions and sits alongside other evidence‑based ratios such as 40/20 and 30/30 in coaching literature. (inscyd.com) (inscyd.com) Meta‑analyses of HIIT versus moderate continuous training report that repeated high‑intensity intervals produce larger acute increases in post‑exercise oxygen consumption and comparable or superior improvements in maximal fat‑oxidation over weeks of training in overweight adults. (sciencedirect.com) (sciencedirect.com) Canadian Running’s “Race‑day tips for a smooth spring comeback,” shared on its social feed March 20, 2026, emphasizes practical race logistics—packing warm, dry layers, post‑race snacks and electrolytes—and managing expectations after a winter break rather than chasing a personal best on the first outing back. (runningmagazine.ca) (runningmagazine.ca) Those Canadian Running tips also recommend routine pre‑race steps used by many coaches: arrive early to allow a 10–15 minute active warm‑up, plan mid‑race familiar faces for a mental boost, and prioritise recovery time after the finish to protect gains from the event. (runningmagazine.ca) (runningmagazine.ca)