One Minute of All-Out Exercise May Have Benefits of Forty Five Minutes of Moderate Exertion.
nyt 
Athletes rely on intervals to improve their speed and power, but generally as part of a broader, weekly training program that also includes prolonged, less-intense workouts, such as long runs.
Fundamental questions have remained unanswered about just how well these very short, very intense workouts really stack up against traditional, endurance-style training.
Scientists at McMaster University mounted probably the most scientifically rigorous comparison to date of super-short and more-standard workouts.
By the end of the study, published in PLOS One, the endurance group had ridden for 27 hours, while the interval group had ridden for six hours, with only 36 minutes of that time being strenuous.
Result is that three months of concerted endurance or interval exercise can notably and almost identically improve someone’s fitness and health.
research
Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment. plos
.
By best cycle training has been riding rolling hills outside of Portland. Second best has been riding a fixed-gear on my daily commute. Least valuable is riding with electrical assist that takes the intensity out of my commute.
Also, Contestants lost hundreds of pounds during Biggest Loser, season 8, but
gained them back. A study of their struggles helps explain
why so many people fail to keep off the weight they lose. nyt