Woldemar Gerschler was the first to explore the SCIENCE of anaerobic high intensity intervals (about 25-30s or 200yds) in the 1930s. Gerschler wouldn’t let you begin the next interval if your heart rate didn’t drop below 120bpm within 90s rest. If this didn’t happen, the session was deemed to be too difficult and the session would be adjusted. If only his “adjustment” would be better published to avoid those who push into greater stress and lesser performance.
Hungarian coach Mihaly Igloi in the 1950s would decrease workload if a hint of form was broken or motion stiffness shown. He watched form like a hawk. Pete Mundle at the University of Oregon wrote a paper on this that Bill Bowerman came to use. Igloi, and then Bowerman, would use such intervals 2-3x weekly, separated by easier days consisting of either a long easy workout, a lot of stretching, or strength training. Without the easier days, 8-10 weeks later produced fatigue with decreasing performance, and a lot of pulled calf/Achilles tendons, often being 6 months before normal performance could again be achieved due to down time from injury, fatigue, or simply the inability to get better.
Bowerman would tell his runners that they should finish workouts feeling “exhilarated, not exhausted.” Why should this be any different for any workout? He would say that it is better to underdo than overdo. This is the hard-easy method, and Bill would call it “stress, recover, improve.” He’d say, “…you’d think any fool could do it.”
We often try, but we usually program HIIT too often in our program, too early in our program before we are ready, with intervals that are too long, and we do not allow for proper rest/recovery between intervals and days of training.
Let’s do better. Work hard. Have fun. Plan and perform well.