Revised: mostly shaded park makes a controlled outdoor moderate session reasonable. Keep it brisk but smooth; no hard hill attacks or pace chasing. Main target 115–125 bpm. Outdoor HR is spiky: brief 126–130 readings are acceptable if they settle quickly. If HR stays >125 for 2–3 min, slow to easy shaded walk or pause at a bench. If the loop has sun patches, wind, crossings, or HR runs hot early, downgrade to Z2 at 110–120 for the rest. Hard stop 128 sustained / symptoms. Stop for dizziness, chest symptoms, unusual shortness of breath, headache, calf pain, or feverish/body-ache feeling. Drink small sips; avoid repeatedly raising the watch arm while checking HR.