Embrace the slow run.
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Interval training has taught us that you need to keep the intensity high to get the maximum benefit from every mile you run. This is a fine strategy for basic fitness, but it will never get you to the front of the pack for a road race. Instead, aim to make 80 percent of your runs easy and 20 percent of them hard. Research indicates that doing most of your running at low intensity, where you can speak comfortably, can improve race times more than running above the ventilatory threshold, where it gets tough to talk. Long, slow runs can be as beneficial as short, fast runs – maximizing blood flow and lowering your resting heart rate – and cause significantly less fatigue. "Those who do more running at low intensity are less tired for the high-intensity sessions and therefore get more benefit from them," says Jonathan Esteve-Lanao, an exercise scientist who specializes in endurance sports.