What is an interval-training workout? An interval-training workout is one in which you alternate periods of hard work (the stress phase) with periods of easy work (the recovery phase). Interval training is a heart-rate-based training program.     What exercises can I use? You can use any mode of exercise that you enjoy (walking, jogging, running, hiking, swimming, etc.). How is an interval-training workout performed? You will need to increase and decrease your intensity levels at these times: Warm up the first 2 minutes at Intensity Level 5. Minute 3 increase to Intensity Level 6. Minutes 4-7, 8-11 and 12-15 work your way from Intensity Level 6 to Level 9, maintain for one minute. Minutes 16-19 work your way from Intensity Level 6 to Level 10 (High Point at Level 10), maintain for one minute. Cool down the last minute to Intensity Level 5.