The studio I train at rents to several other personal trainers, and while most of them are okay there are a few who have no idea what they’re doing. I usually ignore them, but last week during a session I overheard one start training her client on the overhead press behind me and was surprised to hear what sounded like cadence counting. Her instructing and the form her clients usually demonstrate is horrible, so I was happy to hear her trying to do something right even if her cadence was a little too fast.
Then I realized she wasn’t counting cadence; she was counting repetitions. More than one per second.
The only reason I didn’t notice at first was her client wasn’t performing the exercise with a full range of motion and starting each rep at bottom-out, which is a good thing because on subsequent exercises when he did he allowed the weight stack to slam down. From what I was able to observe she had him perform at least three sets of each exercise, and the more he did the worse his form became. Her client was rushing through a full set in less time than my client spent performing only two repetitions.
A few years ago I recorded one of my clients workouts at the house, during which I bumped my head on the Nautilus OME while standing after loading a barbell on the floor near it. Afterwards I was watching the video on fast-forward looking for the part where I screwed up to see if it was obvious and noticed even when viewed at four times normal speed Joe appeared to be moving more slowly and with better control than most people you see in the gym.
I’ve trained people who previously did CrossFit or similar programs emphasizing fast movement and a high volume of mechanical work over quality or efficiency of muscular loading. They always comment on how much harder an exercise is when done at a slow, controlled pace. While part of the increase in difficulty has to do with moving in a manner that more effectively loads the targeted muscles, a lot of it has to do with the longer duration. All else being equal, it is harder to perform ten eight-second repetitions than ten one or two-second repetitions simply because of the longer time under load.
This is one of the biggest problems when comparing single and multiple set programs or discussing single versus multiple sets with most trainees; most people have a very different idea of a set than the kind of strict, slow, controlled form involved in most high intensity training protocols.
Before even thinking about comparing the effectiveness of a different number of sets it is necessary to determine the most effective style of performance. Otherwise you’re just comparing the relative effectiveness of doing it very poorly one or more times.
Most exercise research on single versus multiple sets doesn’t specify or standardize repetition cadence, and when it does it is usually not supervised and timed to ensure strict compliance. Instead, subjects are often self-supervised and most people without proper instruction will use relatively poor form, moving in a fast and sloppy manner not representative of what is often recommended for high intensity training. I have trained bodybuilders and professional athletes who were convinced they had already been training with a high level of intensity comment after a workout with me how much harder it was, so I am also highly skeptical of the average subject’s ability or willingness to push themselves to train as intensely as is often recommended for high intensity training.
The majority of published research and an even larger amount of unpublished research shows little or no difference in results between performing one or more sets of an exercise (research showing no difference in the effect of independent variables tends not to be published). Considering the above, what this really means is there is little or no difference in results between performing one or more sets of an exercise with crappy form.
If we were to compare either a single or multiple set protocol performed in typically sloppy, quick fashion with a single set protocol performed in strict, slow, fashion I suspect the results would still be similar assuming both were done with a high intensity of effort. However, in the long run the group performing a single set of strict, slow reps would suffer less wear and tear and fewer training related injuries.
As for optimal training volume I don’t think the issue is the number of sets or reps or the mechanical work performed so much as the metabolic work and stress on the body, which is more a matter of set duration. This is another reason not specifying and ensuring compliance with a specific repetition protocols in exercise studies is such a huge mistake. As the stress on the body increases you will reach a point of diminishing returns, and beyond some point you will begin to plateau or even regress. While a longer set duration allows the use of a safer level of resistance the longer the time under load the more each set contributes to the overall stress on the body and the fewer can be performed before reaching a point of diminishing returns or overtraining. While there may be little or no difference in results between performing one or more sets in typical fashion, the higher the set duration and relative effort the more of a negative effect on results additional sets are likely to have.
Single set high intensity training protocols makes sense for several reasons. Safety and preservation of long-term functional ability should be the highest priority of program design, so exercises should be performed at a reasonably slow speed and using a level of resistance that can be used for a reasonable number of repetitions in strict form. Because this will result in a longer set duration it is necessary to be more conservative with the number of sets and since research shows little or no difference between performing one or more sets at typical faster speeds and very short durations it is unlikely there would be a benefit to performing more than one set of a longer duration.
With a single set protocol you can perform more exercises or more directly work more muscle groups in a single workout without exceeding an optimal volume of exercise.
It is easier to objectively compare performance of a single sets of an exercise over time than multiple sets without perfectly standardizing interset rest intervals.
All else being equal (duration of sets and rest intervals) single set programs are more time efficient.
Carpinelli RN, Otto RM, Winett RA. A Critical Analysis of the ACSM Position Stand on Resistance Training: Insufficient Evidence to Support Recommended Training Protocols. Journal of Exercise Physiology Online 2004;7(3):1-60
Fisher J, Steele J, Bruce-Low S, Smith D. Evidence Based Resistance Training Recommendations. Medicine Sportiva Med Sport 01/2011; 15:147-162.
Maisch B, Baum E, Grimm W. Die Auswirkungen dynamischen Krafttrainings nach dem Nautilus-Prinzip auf kardiozirkulatorische Parameter und Ausdauerleistungsfähigkeit (The effects of resistance training according to the Nautilus principles on cardiocirculatory parameters and endurance). Angenommen vom Fachbereich Humanmedizin der Philipps-Universität Marburg am 11. Dezember 2003
Smith D, Bruce-Low, S. Strength Training Methods and The Work of Arthur Jones. Journal of Exercise Physiology Online 2004;7(6): 52-68
Westcott WL, Winett RA, Anderson ES, Wojcik JR, Loud RL, Cleggett E, Glover S. Effects of regular and slow speed resistance training on muscle strength. Journal of Sports Medicine and Physical Fitness. 2001 Jun;41(2):154-8