As further evidence of our society's disinclination to spend time on keeping ourselves healthy, yet another study has come out regarding the benefits of High Intensity Interval Training. This one, out of Ontario’s McMaster University, aimed to get ever closer to finding the minimum effective dosage for a host of health-related cardiovascular benefits and arrived at...one minute (sort of). The protocol was as follows:

2 minute warm-up

20 seconds all out

2 minute rest, Repeated three times

3 minute cool down

….performed three times weekly.

The study showed improvements in skeletal muscle mitochondrial capacity, blood glucose levels (in men only), systolic blood pressure and mean arterial pressure, insulin sensitivity, and VO2 max over six weeks. The major caveat to the study is that it was performed on sedentary and overweight subjects, rather than people who already maintained a reasonable level of fitness. Additionally, we’re not looking at only one minute of exercise, we’re looking at 10 minutes in actual time, though it’s only one minute at the highest intensity available (450-500 watts). So how can these findings be applied?

First, take note of the work intervals. They’re 20 seconds long, which is the same length as in Izumi Tabata’s famed protocol originally used with trained speed skaters. Excluding the warm-up and cool-down, that protocol was 4 minutes long, but only gave 10 seconds rest between work periods. It’s over twice the high intensity work with less rest, and would kill the participants in the McMaster study, but together they provide good evidence that a lot can be accomplished in a 20 second work period if you maintain a high level of intensity, whether you are highly trained or sedentary.

Second, you have 2 minutes of rest in the McMaster protocol. That can be a lot as you get into better shape, and since we're talking about working around time constraints here, why not shorten the time even more? As people become more trained, this can be achieved, as long as the intensity of the work phases do not drop as well. One simple way to identify this is to record the ‘work’ achieved at ‘sprint’ intensity (calories on an airdyne, rounds on an elliptical, ‘touches’ on a slideboard, swings with a kettlebell) over a few workouts performed with a 2 minute rest period, and make sure that that workload performed during the work period stays constant--or increases--as you decrease the rest period.

Keeping the intensity of the work periods high is something I can’t emphasize enough. If the intensity drops, and the lines between work and rest become blurred, we’re getting closer and closer to steady state exercise, which when performed for short periods is not enough to effect significant changes. On the other hand, if you can maintain (or even better, increase) the intensity of the work phases, we know that you can progressively drop to even 10 seconds of rest.

Third, if you want a better workout, and can’t seem to ratchet up the work performed during the work periods any higher, before you try dropping rest time, try adding another sprint. What's another 20 seconds?

Fourth, keep in mind that if you already work out, but aerobic stuff just isn’t your thing, you can probably trim this down even further and get some cardiovascular benefit. You should be doing any conditioning work after a lifting program, so you could probably cut down the warm-up period significantly (to 30 seconds perhaps, just to get a feel for the activity). You could add bike sprints right after a small muscle group exercise. Are you doing curls for the girls or calf raises for your chicken legs to round out your workout? Do a set and immediately do your sprint, then spend another 60-75 seconds in active recovery before going back to your beachbody exercises.

Finally, this is an article reviewing a study on health benefits for those who are time-constrained. Be careful about trying to apply this information to a specific sport. The McMaster study was to determine the minimum effective dose for improving health. Athletes need to keep in mind the demands of their sport. For most sports two minutes is far too much rest to achieve the needed levels of conditioning. For pole vaulters, 20 seconds of sprinting is probably more work than you need.

The AMAZING One Minute Workout