A H.I.T.-less At-Bat, Part 6: My Response to Carpinelli’s Review of My Strength Meta-Analysis

This post represents part 6 of a multi-part series where I respond to Dr. Ralph Carpinelli’s critique of my meta analysis on single versus multiple sets for increasing muscular strengthIn part 1, I gave you some background on Dr. Carpinelli and my meta-analysis.  In part 2, I showed you how Carpinelli misleads the reader by omitting important information about my paper.  In part 3, part 4, and part 5, I showed you how Carpinelli’s objections to my inclusion of the Rhea, Kemmler, and Kraemer papers were not justified.  In this section, I address Dr. Carpinelli's objection to my use of a 1-RM strength criterion.

1-RM For A Reason

Dr. Carpinelli notes how one of my inclusive criteria for my paper was that a study must have reported the pre-training and post-training 1-RM.  Dr. Carpinelli then attempts to insult my intelligence by stating:

"Perhaps Krieger mistakenly believed that the 1RM is the only way to assess strength gains."

He follows with this statement:

"That belief is not supported by the scientific literature."

By following with such a statement, he infers that I automatically believe that 1-RM is the only way to assess strength gains, and again misleads the reader as he has in earlier parts of the paper.  Nowhere did he attempt to formulate alternative explanations for my 1-RM criterion, and at no time did he attempt to contact me to clarify why I had this criterion.  He goes on to note papers that used pre- and post-training 3-RM as a measure of strength, and questions why I did not include these papers.  He again makes accusations of bias, stating:

The question is whether Krieger was unaware of these studies, which were all published prior to his meta-analysis, he did not include them because of his arbitrarily predetermined 1RM criterion, or simply because 1-set and 2-set training produced similar strength gains.

Carpinelli constructs a false trichotomy by presenting the reader with only three possibilities as to why I omitted these studies:  either I purposely left them out because of no significant differences in gains (implying that I was biased and purposely manipulating my data), I left them out because my 1-RM criteria was "arbitrary", or that I was unaware of the studies.  None of these are true.

My 1-RM criteria was not arbitrary.  Strength and endurance exist on a continuum.  For example, a 1-RM does not take much endurance, but a 20-RM does.  While a 20-RM has a strength component, endurance becomes a large component as well.  Thus, the decision must be as to where do you cut off the strength criteria.  A 3-RM has a small endurance component compared to a 1-RM; this is true because a 3-RM does not perfectly correlate with a 1-RM (although the correlation between the two will be strong).  Thus, the only logical cut-off point is to have a 1-RM.  Any cutoff point beyond a 1-RM becomes arbitrary.  Thus, Carpinelli's claim that my 1-RM criterion was arbitrary is false.

Also, the 3-RM studies that I left out would still have been omitted even if they had tested a 1-RM.  This is because these studies compared 1 set of an upper body exercise and 2-sets of a lower body exercise.   They did not compare single and multiple sets for the same exercise, and would not have met my inclusion criteria for all other factors being equal between the groups other than the number of sets.  It is baffling as to how Carpinelli would overlook this fact.  Thus, Carpinelli's insinuations of bias have absolutely no merit.

Carpinelli then goes on to state:

Most of Krieger’s [5] inclusive studies compared 1-set with 3-set training and he claimed that 2-3 sets were significantly better than one set for strength gains. If there really is a dose-response relationship between the number of sets and strength gains – as many multiple set proponents believe – then two sets should be better than one set and three sets should be better than two sets. Although Krieger had a section entitled Dose-Response Model, he failed to report on this potential relationship.

Dr. Carpinelli fails to tell the reader that only two studies in my analysis involved 2 sets per exercise, and one of them varied the sets between 2 and 4 (although the average was rounded to 2).  Since there was only two studies that involved this number of sets, the sample size was inadequate to compare this to 1 or 3 sets.  Thus, this required the 2 set category to be lumped in with the 3 set category.  There would simply be not enough statistical power to compare 2 sets to 1 set, or 2 sets to 3 sets.

For example, let's say I am comparing the average test scores of 3 classrooms; I want to get an idea of how well each teacher is doing.  One classroom has 10 people, the second had 20 people, and the third only has 2 people.  Because the third classroom only has 2 people, it is inappropriate to statistically compare this classroom to the other classrooms which have much larger sample sizes.  Dr. Carpinelli criticizing me for not comparing 2 and 3 sets is like Dr. Carpinelli criticizing someone for not comparing average test scores of a classroom of 20 people to a classroom of 2 people.  A classroom of 2 people may not be a representative sample to determine how well that particular teacher's students perform on a test, and there would be inadequate statistical power to compare the classrooms.

Also, Carpinelli's claim that if there is a dose-reponse relationship between the number of sets and strength gains, then 2 sets should be better than 1 and 3 should be better than 2 is false.  Dr. Carpinelli fails to consider that the relationship between strength gains and set volume may not be linear.  For example, perhaps the increased gains do not present themselves until a threshold of 3 sets is reached, or perhaps the difference between 1 and 2 sets is extremely small, with a sudden jump with 3 sets.  There are many possibilities that Carpinelli does not consider.

The bottom line is that Dr. Carpinelli's objections to my 1-RM inclusive criterion are not justified, and his critique of my grouping of 2 and 3 sets is inappropriate due to the lack of available studies using 2 sets, as well as the fact that the relationship between strength and set volume may not be linear.

In part 7, I will address Dr. Carpinelli's claims of "Numerological Abacadabra."  Stay tuned...


Get the latest science on muscle gain and fat loss every month

Keeping up with the research is tough, so let us do the work for you. Consider signing up for Research Explained in Practical Summaries (REPS). We cover five studies per month and break everything down for you, so you don't need a PhD to interpret the data. Click here to learn more.

Get access to over seven years of past research reviews, video content, and Q&As on training and nutrition

Get access to the Weightology Archives of over 400 video and written research reviews, evidence-based guides, and Q&As. A total of 7.5 years of content! A huge variety of topics related to muscle building, fat loss, nutrition, and fitness are covered. Click here to obtain lifetime access.  
0 0 votes
Article Rating
Notify of
Inline Feedbacks
View all comments
5 years ago

Where’s part 7?

Ken O'Neill
10 years ago

Wonderful. Carpinelli et al bring an eerie sense of the Inquisition persecuting the Scientific Heresy!

Looking forward to your next installment.


11 years ago

Lengthy but great read none-the-less James. Although Carpinelli did open my eyes to the fact that some claims upon scrutiny may not be set in stone, i think it has become a case of swimming against the tide for the sake of swimming against the tide. I also realise in saying what i am about to that this article isnt really about this issue, the issue of the dose-response relationship of volume for strength/hypertrophy gains is never static. It is always in a state of flux based on the individuals genetics and environment (training status). Yet i seldom hear this… Read more »

11 years ago

Well said James.

The ability to produce increased sub-maximal levels of force is not the same thing as increasing strength.

A powerlifter who has increased his 3-RM deadlift by 10-pounds is unlikely to be considered stronger if his 1-RM happens to remain the same as before.

Looking forward to part 7.

Would love your thoughts, please comment.x