Recently Dave gave me an amazing book to read called ‘Think Again’ by Adam Grant.  (He is the author of the New York Times article and podcast on languishing that has made the rounds recently).  If I had to describe the book in one sentence it would be this:

There can be a lot of joy in being wrong, but only if you let yourself be wrong and are willing to reframe your thinking. 

I am now going to provide 2 examples of this concept; the good and the bad.

First the good:  In March 2019 I wrote a blog about the benefits of high intensity interval training, particularly sprint training, and how it is superior for fat loss.  I now accept that my thinking is wrong on this idea, and I enjoyed learning updated research that reframed my outlook on this topic (for now anyways).

And now the bad:  The strength and conditioning world is full of dogma.  A high profile strength personality named Brad Schoenfeld went back to school and obtained a legitimate PhD in exercise science.  His contribution has been to challenge all of the old school practices surrounding weight training that have been assumed by weight lifters to be correct for no other reason than ‘that is the way things have always been done’.

Dr. Schoenfeld has been a bastion of high quality, thought provoking research that has really turned the strength world on its head.  Yet, most involved in that community are not willing to ‘think again’ (see what I did there) and instead have chosen to attack him as a person instead of reframing their thinking on the topic.

Enter this weeks blog.

Dr. Schoenfeld and his group have just put out what will likely be a very influential paper that is pre-print (meaning it hasn’t even been released in a medical journal yet).  The topic?  The very same as the blog I wrote in 2019.

This is a meta-analysis which is the highest quality of research out there.  A meta-analysis essentially groups data from all pertinent studies on a topic and draws conclusions based on the grouped results.

This meta-analysis compared body composition changes between interval training and moderate intensity continuous training.  In short, the paper is meant to establish which method is best specifically for fat loss.

Now the dogmatic part – most folks in the strength world will insist that high intensity intervals not only have a greater impact on body composition (decreasing fat mass instead of lean mass), but some even claim they will help you increase your total lean mass.

Well……think again.

The study defined Moderate Intensity Continuous training (MICT) as moderate effort (<80% of your heart rate or aerobic capacity) and performed in a longer single bout.

Interval training (IT) was defined as multiple shorter bouts interspersed with recovery periods either at lower intensities of effort or complete rest.  This can be further divided into High Intensity Interval Training (HIIT) and Sprint Interval Training (SIT).  To make it simple, think of sprint intervals as absolute max effort for very short duration, while HIIT is slightly lower intensity and longer duration.

Historically this has been a very controversial topic.  A prior meta-analysis showed that intervals produced a whopping 28.5% greater reduction in fat mass compared to moderate intensity continuous training.  This provided a lot of ammo to dogmatic strength trainers.  In fact many STILL cite this article as absolute evidence that they are correct.  But the study was extremely flawed.  In fact it was so flawed, that the journal that published it ended up retracting the article altogether (an occurrence that rarely ever happens in published literature).

Dr. Schoenfeld’s article is a large meta-analysis so holds more merit.  They reviewed over 2000 papers and included 56 in their results after all the exclusion criteria.

To sum things up succinctly, here were the basic conclusions:

• CHANGES IN FAT MASS: The argument for intervals has revolved around something called a greater excess post exercise oxygen consumption (EPOC). Essentially your engine continues burning well after you are done exercising.  But it turns out the overall additional energy expenditure is negligible so unlikely to impact fat loss.  Their conclusion reads:
  • “Taken as a whole, these findings suggest that changes in fat loss are not meaningfully influenced by the intensity of effort during exercise.”
• CHANGES IN BODY COMPOSITION: When compared to non-exercising control groups, both intervals and longer duration exercise were better……but barely. In fact, the typical was only 0.22 or 0.25kg (about a half of one pound).  The issue is that no studies combine exercise AND dietary intervention.  The take home here is that diet plays a much more important role than either type of exercise in terms of fat loss and body composition.
• REGION SPECIFIC FAT: Interval trainers will cite old papers stating that somehow intervals specifically target abdominal fat when compared to slow cardio.  This presumption was completely refuted in this paper.  In fact, there seems to be no such thing as ‘region specific fat loss’ in terms of cardiovascular activity.
• CHANGES IN LEAN MASS: Unfortunately (yet kind of expected), neither form of exercise mediates hypertrophic adaptations (muscle growth).

So is this good news or bad?

Well you could easily look at these findings and be discouraged by the fact that neither endurance training or interval training seems to have a meaningful difference in fat loss.  In reality you must change your diet to lose fat.

OR, you could think again and realize two tangential conclusions:

• The intensity of effort doesn’t really matter. In intervals you are exercising hard, but short.  In continuous moderate intensity cardio, you are exercising light and long.  Both have the same contributions to overall health.  So you can now feel free to choose whichever is best for you.  Have a time crunch?  Do a 20 minute peloton workout.  Want a mid-day mental break?  Go for a 60 minute walk/run.  Both have the same desired positive impacts.
• We learned something new. Something important.  One old adage that I don’t need to ‘think again’ about sums this up nicely:

“You lose weight in the kitchen (diet), you look good in the gym (exercise)”.