During prolonged exercise, the intensity of the workout and whether a person is a trained runner or not account for about one-third of the differences in how much growth hormone their body releases.

Sprint athletes get a much bigger spike in their growth hormone after a hard 30-second sprint than endurance athletes do — their bodies react differently because of their training.

Men who regularly train for endurance sports show higher and longer-lasting increases in growth hormone during and after long workouts compared to men who do not train for endurance sports.

Women have higher levels of growth hormone at rest and during the first 30 minutes of moderate-intensity treadmill exercise compared to men, regardless of their training background.

When athletes do their hardest sprints, how fast they go and how much lactic acid builds up in their blood can explain most of why their growth hormone spikes — it’s closely tied to how intensely their body is working.