One hard 4 minute session seems to have effects similar to 4 x 4minute sessions. The whole study is available and worth looking through:
There is a further write up here.
Low- and High-Volume of Intensive Endurance Training Significantly Improves Maximal Oxygen Uptake after 10-Weeks of Training in Healthy Men
Conclusion
Our study demonstrated that slightly overweight and healthy individuals only required brief, duration bouts of exercise with good effort three times a week, to produce large increases in VO2max and work economy and reduce blood pressure and fasting glucose levels. Additional studies to examine both adaptations at the molecular level and feasibility for public health appear warranted.
There is a further write up here.
Comments
These are the gems that are worth continuing to share.
Say I do a 4 min warmup and am running about 70% of my Max - 136... I have a hard time running it to 153... I just can't run that fast and that hard to make it jump so quickly... so is the 153 the number at the end of the sprint? or do I do the sprint at 153 the whole way?