Racing every run
Instagram posts stamped with the mileage and time certainly look better with faster paces. However, without recovery days, your body never has a chance to grow stronger after those hard workouts, warns Warrenburg. Plus, relaxed-pace efforts build mitochondria, tiny powerhouses in your muscles that process fat and glucose into the energy you need to run, says Hamilton. Easy runs also strengthen tendons, bones and slow-twitch muscle fibres, the type that carry you beyond short sprints.
INSTEAD Limit hard running to one or two days per week (with the hardest miles counting for only about seven per cent of your weekly total, Hamilton advises). On other runs, you should be able to speak in full sentences with your running buddies, says Warrenburg. And if the pressure of going public tempts you to pick up the pace, leave your watch at home or turn off your training app on those days.