Running is good. It’s quick, free and helps boost your fitness. If you want to use running to get in shape fast, one of the best ways to go about it is to use intervals. Say hello to the Norwegian 4x4 Protocol.
The Norwegian 4x4 Protocol is a powerhouse workout designed to boost your cardiovascular health and stamina in just under 30 minutes. The protocol consists of four intense four-minute intervals at 90-95% of your maximum heart rate, each followed by a three-minute active rest period at 50-60% intensity.
