What is HIIT?

High Intensity Interval Training (HIIT) is exercise with the target intensity existing in submaximal VO2max between 85% and 95% of your peak heart rate. This type of training was born out of the research on Sprint Interval Training, where shorter bouts of intense exercise presented an equally effective alternative to continuous endurance training of moderate intensity to improve cardiorespiratory fitness and health.

After 20 years of research, we now understand that although HIIT protocols are more time efficient, they are not superior to conventional exercise training for the general population.

But are they really time efficient?

Take the wildly popular Tabata protocol for example: 20s of work at ultra-maximal intensities at 170% VO2max (do you really think you’re working this hard?) followed by 10s rest repeated for 8 bouts, can be completed in only 14 min (5 min warm-up + 4 min of training + 5 min cool-down) versus 30 mins of steady-state cardio at a moderate intensity to achieve similar results.

Shorter, yes, but not by much. AND, the actual Tabata protocol is 6 sessions/week with 5 sessions as previously stated and 1 session of steady-state exercise at 70% VO2max for 30 minutes.

→ Is this what your CrossFit routine looks like? Maybe so, but wait, there’s more. . .

Further still, steady-state exercisers in the Foster experiment were fully recovered and ready to ‘return to normal life’ immediately following the conclusion of their cool-down period, while exercisers in the Tabata HIIT protocol remain visibly distressed at the end of their cool-down period and often require an extended period of time to recover to the point where they could again pursue normal activities.

I don’t know about you, but the extra recovery time with HIIT counts towards my total exercise time. Maybe it’s not 15 mins, but now we are eking closer to that 20-30 mins of the conventional steady-state exercise time allotment.

What about Enjoyability?

The name of the game here is sustainability. If an exercise is not enjoyable, then you are less likely to be consistently active and eventually the program will become unsustainable. Across all measures, Foster's research suggests that the enjoyment of training programs indicates that HIIT protocols are significantly less enjoyable than steady-state exercise or even moderate intensity interval training.

We also know there is progressive loss of enjoyment across all training protocols, suggesting that variety of exercise is as important as the type of exercise; particularly considering that the health benefits of exercise have to be viewed in the context of the likelihood that exercise is continued for several years, not just the weeks of a controlled study (Foster et al, 2015).

Perhaps, as Foster suggests, in our search to find the ‘perfect exercise’ we have missed the more important issue of how to make exercise enjoyable enough to be continued long term, and this is our quest as humxn's. We are not born to exercise, we are born movers: we walk, run, play sports, dance, and complete tasks. We like challenges, but the work needs to be fruitful and not mindlessly exercising ad nauseum.

Just Move,


Articles Referenced in the blog post:

  1. Gist, N.H., Fedewa, M.V., Dishman, R.K. et al. Sprint Interval Training Effects on Aerobic Capacity: A Systematic Review and Meta-Analysis. Sports Med 44, 269–279 (2014).

  2. Foster, C., Farland, C. V., Guidotti, F., Harbin, M., Roberts, B., Schuette, J., Tuuri, A., Doberstein, S. T., & Porcari, J. P. (2015). The Effects of High Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity. Journal of sports science & medicine, 14(4), 747–755.

  3. Ito S. (2019). High-intensity interval training for health benefits and care of cardiac diseases - The key to an efficient exercise protocol. World journal of cardiology, 11(7), 171–188.

  4. TABATA, IZUMI; NISHIMURA, KOUJI; KOUZAKI, MOTOKI; HIRAI, YUUSUKE; OGITA, FUTOSHI; MIYACHI, MOTOHIKO; YAMAMOTO, KAORU Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and ˙VO2max, Medicine & Science in Sports & Exercise: October 1996 - Volume 28 - Issue 10 - p 1327-1330