Varying your training intensity always beats steady-pace jogging – but not all intervals are alike. Short, super-intense bursts of cardio with long periods of rest can enhance your speed and endurance, an Australian study found.

For six weeks, athletes did four-minute, high-intensity running bouts separated by four minutes of recovery, or 30-seconds, very-high-intensity intervals divided by two-and-a-half minutes of rest.

The two groups made similar endurance gains, but the 30-second group saw a greater increase in sprint speed. Very intense intervals boost aerobic power and train your body to recruit more muscle, says study author Dr Christian Lorenzen.