Bodybuilding, Strength Training

October 1, 2022

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Do You Have to Add Load to the Bar to Build Muscle?

Progressive overload is a well-established principle for achieving continued progress in resistance training programs. In general terms, progressive overload can be defined as consistently challenging the neuromuscular system beyond its present capacity. It’s commonly accepted that this requires an increase the amount of weight on the bar as one gets stronger to maintain the intensity of effort in a targeted loading zone (i.e., repetition range). However, little attention has been given to other methods of progressive overload, such as increasing the number of repetitions over time. Surprisingly, no study to date had endeavored to investigate the topic in a controlled fashion.

Until now…

We sought to fill this gap in the literature with our just-published study, Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. Before getting into the the specifics, first a little background info…

This study actually was the brainchild of my colleague, Jared Feather. Jared was planning to carry out this study as part of his doctoral work several years ago. He contacted me in 2019 about the possibility of conducting the study under my supervision at Lehman (he had intended to pursue his doctorate at AUT in New Zealand but collect data in the USA). Ultimately, Jared decided to forego his doctorate for the time being to work for Renaissance Periodization. That said, we discussed the importance of filling a gaping gap in the literature and concluded that the topic needed to be investigated regardless. Thus, I agreed to take on the project and carry out data collection in my lab.

In Spring 2020, we set out to conduct the study. We were about halfway finished with data collection when Covid-19 hit; by mid-March, we had to cease all research-related activities. Our research team had devoted over 500 hours of time to the study, but sadly it was all for naught; none of the data could be used.

Despite this setback, we were determined to complete the study.

Fast forward to Fall, 2021. My master’s degree student, Daniel Plotkin, expressed his interest in taking on the study for his thesis, with support from our terrific team of research assistants at Lehman. (Side note: Daniel has since graduated our program and is now pursuing his PhD under the mentorship of Dr. Mike Roberts at the University of Auburn). Fortunately, there were no issues with Covid this time around, We finalized data collection and statistical analysis in Spring 2022, and received official word of acceptance of our manuscript from PeerJ in September 2022.

If you want to delve into the technical aspects of the methods and findings, give the paper a read; it’s open access. For those who’d prefer a consumer-friendly synopsis, here’s the scoop…

What We Did

We randomized a cohort of young men and women with at least 1 year of consistent resistance training experience to perform a lower body training program where they either aimed to increase load while keeping repetitions constant or to increase repetitions while keeping load constant. The training protocol itself was otherwise identical between groups, consisting of 4 sets of the back squat, leg extension, straight-leg calf raise and seated calf raise performed twice per week. Training lasted 8 weeks, with testing performed pre- and post-study. To evaluate muscular adaptations, we carried out a battery of assessments including changes in muscle thickness of the quads and calves via B-mode ultrasound, total and regional body composition via multi-frequency bioelectrical impedance analysis, and 1RM in the Smith machine squat.

What We Found

Overall, results for most measures were quite similar between groups. Rectus femoris growth modestly favored the group that progressed by adding reps; hypertrophy of the other muscles did not show appreciable differences between conditions (see image below). Although strength increases slightly favored the group that progressed by increasing load, the range of effects spanned from relatively modest negative effects to appreciable positive effects and thus are of questionable practical meaningfulness. Other tests of local muscular endurance and power showed no benefit to one progression model compared to the other.

What are the Practical Implications of Findings

The results of our study challenge the generally accepted theory that progression must be carried out through increases in load. In fact, increasing repetitions at the same load showed similar gains in hypertrophy in most of the muscles we assessed, and there was even a modest benefit for hypertrophy of the rectus femoris. While strength increases slightly favored the group that increased load, the results showed a wide spread of variance that calls into question their practical significance. When considering the findings as a whole, both progression models were effective in enhancing muscular adaptations in a cohort of trained lifters and can be considered viable programming options.

Now before jumping to absolute conclusions, it’s important to note that the study only lasted 8 weeks. Although this is typical of training mesocycles, particularly for those of more advanced lifters, we cannot necessarily extrapolate results over longer time periods. Thus, our findings do not necessarily mean that a lifter can continue to simply increase reps forever without adding load to the bar at some point. Evidence suggests that training with very high rep ranges (>40 or so per set) tends to impair increases in hypertrophy. This would seem to be most relevant to those with less resistance training experience, as the ability to increase reps to such an extent is diminished in well-trained lifters. Hence, it’s conceivable that more advanced lifters can continue progress by adding repetitions for longer periods of time; this hypothesis warrants further study.

I’d also note that our protocol targeted a moderate repetition range for the initial training loads (10RM). It is well-documented that maximal strength gains are achieved with the use of heavy loads (at or near 1RM). Thus, these results are not necessarily applicable to strength athletes (e.g., powerlifters) or those who are most concerned about optimizing dynamic strength. In these cases, some type of load progression seemingly would be necessary to maintain training close to maximal loads.

Take-Home Conclusions

Overall, our study suggests that, from a hypertrophy standpoint, progressive overload can be made by altering load, repetitions, or conceivably a combination of the two, at least over the course of typical mesocycles (i.e., 8-week training block). Given that rectus femoris growth favored the repetitions groups, it is conceivable that progressing reps may be favorable in some contexts over others.

On a more general level, the mode of progression does not have to be an either/or choice. It may be best to employ a variety of progression strategies over time to ultimately elicit optimal improvements in muscular adaptations. In this regard, variety may be the spice of gainz.