SIT to Get Fitter

Here are the results of the study on sprint interval training or SIT. There was an 11% increase in max VO2 after the first cycle, reduced down to 6.4% after the second cycle, and finished at an 8% increase. Were the subjects fitter? Max VO2 notwithstanding, they absolutely were fitter. The reason we know that is because during succeeding sessions, their heart rates were lower for a given workload. They were working just as hard, but they didn’t need to use as much energy to do it.

Is there an explanation for the apparent dip in the max VO2 increase? I think the reason the results appear stymied was that they overtrained. Athletes do intervals of any type once, maybe twice per week. The subjects trained every other day for six weeks—and the max VO2 test is like another sprint training session. If someone were healthy enough and had the doctor’s permission, doing a sprint interval training session once every two weeks is enough. I know it sounds so easy: “It’s just 15 seconds! I get to rest for two minutes.” Trust me, with 30 years as a runner and an exercise physiologist: you get shredded every time you do it. You need complete recovery after that kind of session whether cycling, sprinting on a track, on an elliptical, or whatever.

The Bottom Line

I hope you’ve enjoyed the progression of these recent studies. From a walking program to get fitter and sustain muscle mass in exercising muscles, to the comparisons of bike HIIT intervals versus running HIIT intervals to sprint intervals to get fit a little faster, there’s something for everyone. Just make sure you have your physician’s approval to exercise at the level of each type before you begin.

What are you prepared to do today?

        Dr. Chet

Reference: Medicine & Science in Sports & Exercise. 56(5):876-884, May 2024.