Inspired by the latest article by @GretchenReynold in @NYTHealth about how even initially reluctant adults discover how pleasant HIIT can be, I wanted to share some tips for colleagues who review related manuscripts. This is what to look for. A thread...
The first thing to check is the participants. Look for signs that the participants were not exercise-science students of the researchers. Usually, such students already know what the researchers want to find, have seen their videos online, and their posters on the walls.
If the participants are 20-somethings, then scrutinize the characteristics of the sample. When the researchers say "recreationally active," then there is a good chance the participants were athletic. Check the VO2max, if available.
This is a trick first tried by Bartlett et al. (2011), who called their participants "recreationally active" despite a VO2max of 57 ml/kg/min, which is in the top 3% for the age-group norms. It worked for Bartlett, so the term has since been used several times.
If the researchers say their participants were "inactive" 20-somethings, this is also a sign. College students are almost never below activity recommendations. If the participants are called "inactive" but the definition does not refer to physical inactivity, there is a problem.
Another sign is when the researchers say that 20-somethings had max aerobic capacity that seems extremely unlikely (e.g., in the bottom 5% for the age-group norm). It's very difficult to find 20-somethings at the bottom 5% of fitness, especially if they are also low-BMI.
In that case, check the criteria for terminating the "max" test and juxtapose them to the standard ACSM criteria. If the researchers invented their own criteria, this may provide an explanation for the improbably low "max" values used to justify the adjective "inactive."
Next, check the intensity of the "high-intensity" intervals for the HIIT condition. This is crucial because, as the popularity of HIIT grew, the minimum threshold of intensity considered "high intensity" dropped. Now, "high intensity" is within what the ACSM considers "vigorous."
In 2008, "high intensity" meant "all-out effort" or "an intensity close to that which elicits VO2peak (i.e., ≥ 90% of VO2peak)"
In 2012, "high intensity" meant "∼90% of maximal heart rate," which is roughly 80% of maximal aerobic capacity.
In 2014, "high intensity" meant "85%-90% of HRmax," which is roughly equivalent to 75%-80% of maximal aerobic capacity.
And in 2018, "high intensity" meant "≥ 80% of maximal heart rate," which is roughly equivalent to 65-70% of maximal aerobic capacity.
It should be clear that "high intensity" does not really mean "high intensity" per se anymore. "High intensity" has now become an alternative, "sexier" label for what guidelines for the general population refer to as "vigorous intensity" (i.e., 77-95% HRmax, 64-90% VO2max).
Remember that, when participants do "85% to 90% of max heart rate," the intensity is just 75% to 80% of VO2max (in other words, just vigorous intensity).
But even that's not really true. If you remember from your exercise physiology, if the duration of the interval is just 60 seconds, oxygen uptake is still rising. So, it's not even going to reach 75% VO2max. It would still be trending toward that but will still be short.
Then, it's essential to check what the "moderate-intensity continuous" (MICT) exercise group or condition was. There are two strong signs of bias: (1) intensity close to or higher than the ventilatory/lactate threshold, and (2) longer than usual duration (e.g., 45 or 50 minutes).
70%-75% of maximal heart rate (i.e., 55%-62% of VO2max) is picked to place MICT participants at or above the VT/LT, and thus stimulate a slow component of oxygen uptake. This will cause the intensity to rise continuously, making a 45-50 min bout very hard to finish & unpleasant.
Never (ever!) accept overall means of heart rate or oxygen uptake over the entire bouts. These data are recorded continuously and must be reported as such. It's possible that, by the end, due to creep, the intensity of MICT was equal or higher than the intensity of HIIT intervals
Next, and this is absolutely crucial. Check when the participants were asked to report their pleasure-displeasure. If the MICT participants were asked DURING exercise but the HIIT participants were asked AFTER the high-intensity intervals, this is the most clear sign of bias.
As intensity rises during high-intensity intervals, pleasure declines. When intensity drops during recovery periods, pleasure increases. So, the reason why researchers ask AFTER the intervals (during recovery) is to avoid recording the lowest levels of pleasure induced by HIIT.
Yes, the relationship between exercise intensity and pleasure-displeasure is THIS close. We showed this in this recent study:…
A proper assessment protocol of pleasure-displeasure during HIIT should capture (at least) the highest point of the peaks (i.e., the end of the recovery periods) and the lowest point of the valleys (i.e., just before the end of the high-intensity intervals).
I hope that peer reviewers will check at least these basic points next time they come across a HIIT manuscript. Raise these issues with the authors & editors. You would not be "difficult" or "hypercritical." You would be doing a service to your field and helping advance science.

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More from @Ekkekakis

29 Sep
I am really surprised that, when I comment on the myriad of (mostly HIIT-related) studies involving tiny samples (e.g., 5-10 per group) and a large number of dependent variables and tests of probability, most people do not see what the problem is.…
In short, the combination of these two factors essentially guarantees two things: (1) you will find something "significant," especially if you don't take any steps to address the inflation of alpha, & (2) whatever you find will likely be non-replicable -- in other words, a fluke.
I am afraid that the Kinesiology literature is becoming so inundated with the combination of small samples and long lists of dependent variables and probability tests (almost always at .05), that we have become desensitized to its devastating consequences.
Read 15 tweets
6 Nov 19
Since we haven't done a critical-appraisal quiz in a while and people seem so fascinated with the finding that "High-intensity exercise [is] best for improving memory," let's do one. The person who identifies the most problems wins.…
So, we have two versions of the sample-size calculations, arriving at the conclusion that either N = 61 or N = 64 provides adequate power for a THREE-group trial (i.e., roughly n = 20-21 per group). The 1st is from the original thesis, the 2nd is from the peer-reviewed paper.
Here, the argument is that the target effect size, based on Colcombe and Kramer (see next tweet), is d = 0.41. And that for 80% power and α = 0.05, the required sample size is 61. Be specific about any problems you see. Image
Read 5 tweets
20 Oct 19
Word of caution: Neologisms such as "affective attitudes," "affective judgments," and "anticipated affective responses" are certainly NOT "affective determinants of behavior." They are cognitions. As such, interventions to change them rely on information, not lived experiences. Image
If you catch yourself thinking that, to change someone's "affective determinants of behavior," all you need to do is TELL someone that she or he will feel better when they exercise, please stop. And read our chapter, in which we try to clear the confusion.…
Please see Kuhn: he explains that, if a paradigm is threatened by anomalies, its proponents "devise numerous articulations and ad hoc modifications" to avoid denouncing the paradigm leading them to crisis. If "affective determinants" are information-based, the paradigm can stand. Image
Read 4 tweets
10 Oct 19
A thread based on slides I am presenting at @theNASEM on Oct 10. This is part of advising for the National Institute of Aging as it plans funding programs for the primary prevention of #dementia and #Alzheimer's Disease. Here we go... Image
@theNASEM Exercise has been shown to be perhaps the most effective neuroprotective intervention. This evidence is mainly based on animal research but some has been corroborated by human studies. At this point, no other intervention can claim the same conglomeration of benefits on the brain Image
According to a meta-analysis in 2018 exercise has a medium positive effect on cognition in individuals with mild cognitive impairment and Alzheimer's. However, most studies are small and some effects seem implausibly large. Image
Read 27 tweets
24 Sep 19
2018 US phys act guideline (left), 2019 UK guideline (right), same approach & numbers. 1) "It's good for you" assumes rationality, which is bounded. 2) "Here's how much you must be doing" based on benefits/risks (like drugs). Disregards that people must CHOOSE to do it long-term. Image
Compare the structure and underlying rationale of the 2018 US & 2019 UK guideline. They reflect the same approach we have used as a field for half a century: (1) Here's a bunch of percentages to convince you of the benefit, and (2) here's the specific amount you should be doing. Image
Exercise prescription guidelines and physical activity recommendations represent our "ultimate" product, the culmination of our knowledge production, and the epitome of the "value proposition" we offer society as a scientific field. So, they must reflect the best we have to offer
Read 16 tweets
7 Mar 18
My kid noticed I was sad this morning and asked why. I explained that one of the heroes of my youth, and a great inspiration to me in becoming a scientist, passed away. We lost an intellectual giant. Rest In Peace, John #Cacioppo. There won’t be another one like you. Image
If you felt arrogant in your knowledge, all you had to do was read Cacioppo. He knew mathematics and physics. He knew history and philosophy. He knew physiology and neuroscience. And he knew psychology. I wanted to be like him but knew I would never be able to.
I will never forget the time, after a conference talk I gave on the circumplex model of affect, out of the crowd walks THE John T. Cacioppo. Shakes my hand, congratulates me on my talk, and tells me that he disagrees with the model. I think my knees buckled.
Read 4 tweets

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