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October 9, 2023

Does supervision during resistance training enhance increases in muscle strength and size

Does supervision during resistance training enhance increases in muscle strength and size in trained lifters compared to unsupervised training?

That’s the question our lab recently set out to answer. The study, led by my master’s student Max Coleman, has now been published in the Journal of Sports Sciences and the results have wide-ranging practical implications.

If you want to delve into the fine points of the methods and findings, give the paper a read. For those who’d prefer a consumer-friendly synopsis, here’s the scoop…

What We Did
We randomized 45 young, resistance-trained men and women to perform a total-body resistance training program either in a supervised (SUP) or unsupervised (UNSUP) manner across an 8-week study period. Both groups performed the exact same exercises (front lat pulldown, machine shoulder press, machine chest press, cable triceps pushdown, dumbbell biceps curl, plate-loaded leg press, machine leg extension and machine leg curl) and program variables (3 sets of 8-12 RM for each exercise with 2 minutes rest between sets).

Participants in SUP were directly supervised throughout each rep of every session, with researchers verbally encouraging them to carry out all sets to volitional failure (i.e., the point where an individual felt that he/she could no longer complete an additional repetition) and adjusting exercise technique when appropriate. Alternatively, those in UNSUP were taken through an acclimation session to demonstrate proper technique on the given exercises and instructed to carry out all sets to volitional failure throughout the training program; they charted their workouts and emailed the corresponding logs to the research staff on a weekly basis.

We assessed the following measures before and after the training program: (1) body composition via bioelectrical impedance analysis; (2) muscle thickness of the biceps, triceps, and quads via ultrasound; and, (3) maximal strength in the bench press and squat via 1 repetition maximum testing.

What We Found
In regard to hypertrophy, the SUP group showed greater increases in muscle thickness for the triceps brachii, the upper portion of the lateral thigh and all regions of the mid-quadriceps. Alternatively, the biceps brachii and mid- and lower aspects of the lateral thigh showed relatively similar hypertrophy between groups.

From a strength standpoint, the SUP group showed greater increases in the 1RM squat; increases in the 1RM bench were relatively similar between groups.

Of note, there were a considerably greater number of dropouts in UNSUP (n=7) compared to SUP (n=2) across the study period.

What Do the Results Mean?

Overall, the findings indicate that direct supervision has a beneficial effect on strength and hypertrophy in recreationally trained young men and women. The magnitude of the effects ranged from relatively small to quite large, suggesting that adaptations could be practically meaningful.

Although we did not attempt to explore the underlying mechanisms for results, it can be hypothesized that intensity of effort was a contributing factor. There is compelling evidence that training with a high level of effort is necessary to optimize muscular gains. Not only did our research team verbally coach participants to go to failure on each set, but findings also may have been influenced by the fact that people try to do their best when being observed (the so-called “Hawthorne Effect”). Notably, when asked about their perceived effort at the end of the study, almost all participants said they trained harder than they ever had before. This would suggest that those in the UNSUP group were generally training with less effort, perhaps below the threshold required for max gainz.

Results also may have been partially attributed to improved training technique. Although the participants all had been training consistently for at least one year, some did not perform exercises in a biomechanically efficient manner and/or did not properly control the weights throughout each repetition (especially on the eccentric action). For those in the SUP group, our research team corrected technique during a set when appropriate, helping to ensure that muscles were optimally stimulated. We can only speculate on the matter, but it’s reasonable to assume that a number of participants in the UNSUP group likely trained with substandard technique, potentially diminishing results.

Another important finding was that the UNSUP group had far more dropouts than the SUP group. At the end of the study, several participants in SUP stated that the supervision made them feel “accountable” to show up for the training sessions. Considering that exercise adherence is paramount to achieving results, supervision would thus be beneficial to a substantial portion of the general population who are not sufficiently motivated to train consistently.

Take-Home Conclusions
So what are the practical implications of these findings?

On a general level, direct supervision during resistance training appears to enhance muscular adaptations for a majority of the recreationally trained lifting public. The supervision could be in the form of a qualified personal trainer or attentive workout partner; essentially, someone who monitors exercise technique and suggests corrections where appropriate and motivates the lifter to push sufficiently hard during each set. Given that individuals who are relatively new to resistance training generally have spotty technique and perhaps a poor understanding/motivation to progressively challenge their muscles, they may benefit to an even greater extent from a supervised program. Alternatively, some advanced lifters (i.e., bodybuilders, etc) may be internally motivated to consistently train with high intensities of effort and hence may not meaningfully benefit from supervision.

The results also suggest that research studies intending to investigate the efficacy of resistance training-induced strength/hypertrophy outcomes should carry out data collection in a supervised environment; it’s the only way to ensure that participants train in a manner consistent with optimizing results. However, while this approach may enhance research efficacy, there may be a disconnect when generalizing the findings from resistance training research carried out under supervision to the recreational lifting public. Namely, if most lifters train suboptimally on their own, they cannot necessarily expect to achieve results similar to those found under supervised conditions. The tradeoff needs be considered by researchers when designing resistance training interventions as well by practitioners when interpreting study findings for program prescription.