I love running, but I'm not a fast runner by any means, and I have no desire to be. I do want to be an efficient runner, though, and the two often go hand in hand. Having taken three months away from my running shoes, I was also keen to boost my cardiovascular fitness again before the new year.
But, as it's winter, I wanted to turn my outdoor runs into treadmill workouts at the gym. It was here that I discovered the Norwegian 4x4 workout, after speaking to a running specialist and personal trainer. Created by the Cardiac Exercise Research Group at the Norwegian University of Science and Technology (NTNU), it's a high-intensity interval training (HIIT) session.
