Net Takeaway: 2 minutes (4 x 30 seconds) of high intensity “all out” cardio intervals equals 90 minutes of long slow cardio. That’s one session. If you extrapolate the results for a week with 3 sessions 6 minutes equates to 270 minutes or 4 1/2 hours. High intensity exercise is both time-efficient and effective. The science of high intensity cardio is applied to the Fitness in 10 for Men workout.
Purpose: This research studied two diverse training strategies: endurance cardio training versus sprint interval training. They measured and compared exercise capacity, molecular, and cellular adaptation in skeletal muscle over a 14 day period.
16 young men were assigned to either to the SIT (sprint interval training) group or the ET (endurance training) group. Each group did 6 training sessions over a 14 day period with 1 or 2 days off in between sessions.
The SIT (sprint interval training) group did 30 second “all out” sprints on a stationery bicycle. The intervals ranged from 4-6 x 30 seconds with 4 minutes recovery. Training time per session ranged from 18-27 minutes including recovery, or 2-3 minutes including intervals only. Total training time over 6 sessions was 135 minutes (2 hr 15 min) including recovery, or 15 minutes including intervals only.
The ET (endurance training) group did continuous training of 90-120 minutes on a stationery bicycle per session. Total training time over 6 sessions was 630 minutes (10 hr 30 min).
The measured time reductions in cycling time trials were similar. The biopsy samples revealed similar increases in muscle oxidative capacity (ability to process oxygen) and muscle buffering (ability to manage the acid causing by exercise).
Conclusion: “In conclusion, the most striking finding from the present study was that two very diverse forms of training induced remarkably similar changes in exercise capacity and selected muscle adaptation that are related to exercise tolerance. Given the markedly lower training volume in the SIT (sprint interval training) group, our results suggest that intense interval training is indeed a time-efficient strategy to induce rapid muscle and performance adaptations comparable to traditional endurance training.”
Martin J. Gibala, Jonathan P. Little, Martin van Essen, Geoffrey P. Wilkin, Kirsten A. Burgomaster, Adeel Safdar, Sandeep Raha2 and Mark A. Tarnopolsky: Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. J Physiol 575.3 (2006) pp 901–911