Cold water immersion (a.k.a., “ice baths”) has become a popular method amongst exercise enthusiasts and athletes to enhance recovery after an intense training bout. The strategy involves exposing either the trained limb or the whole body to very cold liquid temperatures. According to p...
Brad Schoenfeld, Ph.D, C.S.C.S., is an internationally renowned fitness expert and widely regarded as one of the leading authorities on body composition training (muscle development and fat loss). He is a lifetime drug-free bodybuilder, and has won numerous natural bodybuilding titles.
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.
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.
Finished! Yep, last week I completed data collection for my doctoral dissertation study. It is the first study to compare muscular adaptations (muscle hypertrophy and strength) between bodybuilding- and powerlifting-type routines in well-trained individuals. Preliminary results are really interesting. Can’t get into too much detail at this point but some findings were expected while others were not. The implications with respect to the strength-endurance continuum are significant and will certainly help to further our understanding of how to best structure routines for optimal muscular gains. I’ll have a lot more to say on this over the coming months, including some general observations about inter-individual responses that have important relevance to practical applications. Stay tuned.
In case you missed it, last week I wrote a rebuttal blog post to a journal review article by nutrtional researcher, Dr. John Ivy. In his review, Dr. Ivy challenged a previous paper I co-authored with Alan Aragon on nutrient timing, citing what I consider shaky evidence to support a tenuous position. My post was a point-by-point refutation of this evidence. As noted in my post, I respect Dr. Ivy’s body of work and consider him a fine researcher. In fairness, I emailed him a link to the post and offered the opportunity to write a counterpoint article on my site. As yet I’ve not received a response. If and when he replies, I will post his comments in their entirety.
Finally, here’s the lastest episode of the B&B Connection webcast. In this episode Bret and I discuss the science and art of tempo training. Topics include whether fast or slow lifts are better for strength, power and/or hypertrophy; whether there is a benefit to varying cadence; whether eccentric actions require a different cadence than concentric actions, and; whether “superslow” training has a place in a lfiting routine.
It has been well documented that mechanical tension associated with resistance exercise promotes hypertrophic gains. The forces associated with lifting weights alone are therefore capable of producing muscular growth. What is becoming increasingly clear, however, is that metabolic stress associated with moderate to higher repetition exercise also can promote increases in muscle mass. The mechanisms by which this occur are still not entirely clear, but recent research is beginning to give us insight into the possibilities. As discussed in my recent review, several potential factors have emerged as likely candidates. For those who want the cliff notes, here is an overview of each:
Fiber Recruitment: Perhaps the most established way that metabolic stress appears enhance growth is by increasing recruitment of fast-twitch (i.e. type II) muscle fibers. Recruitment follows the so-called “size principle” whereby the smaller slow-twitch (i.e. type I) fibers are recruited first during muscular activity and then larger fast-twitch fibers are progressively called into play as needed to carry out the action. It is believed that the effects of metabolic stress promote fatigue of slow-twitch fibers, thereby forcing activation the fast-twitch fibers. Understand that fibers must be recruited in order to grow; without such stimulation, there is no impetus for the fiber to adapt. Thus, increased recruitment enhances the growth potential of the muscle as a whole.
Myokines: Another possible means by which metabolic stress may enhance muscle mass is by increasing production of local growth factors. Muscle tissue directly produces a number of growth-promoting substances, which have been termed myokines. Local production of a variant of insulin-like growth factor, called mechano-growth factor (MGF), is thought to be particularly important to muscle development and metabolic stress has been shown to increase its production. Numerous additional myokines have also been implicated in the growth process including various interleukins, fibrobrast growth factor, hepatocyte growth factor and others–and many of them appear to be regulated, at least in part, by metabolic stress. Moreover, there is evidence that metabolic stress may reduce various catabolic factors, ultimately increasing the extent of muscle protein accretion.
Reactive Oxygen Species: The term reactive oxygen species (ROS) generally conjures up negative images. The popular media has demonized ROS as injurious substances that wreak havoc on bodily tissues, causing disease and even death. While this view has some credence with respect to chronically elevated levels of ROS, their acute production following exercise has actually been shown to confer positive effects on muscle development. Specifically, ROS are thought to function as key cellular signaling molecules that promote muscle anabolism. There is evidence that metabolic stress heightens ROS production, potentially helping to increase hypertrophy.
Cell Swelling: One of the most novel mechanisms by which metabolic stress may promote muscle growth is via an increase in the hydration of the muscle fiber. This phenomenon, known as cell swelling, has been found to increase protein synthesis and reduce protein breakdown. Well, it just so happens that metabolic stress is a causitive factor in cell swelling, largely from the corresponding accumulation of lactate. Lactate acts as an osmolyte, attracting fluid into the muscle cell. This, in turn, causes sensors in the cell to perceive a threat to its integrity, thereby initiating a signaling cascade that ultimately enhances anabolism.
Acute Hormonal Elevations: This is one of the more controversial areas of research. Studies clearly show that bodybuilding style training (i.e. multiple sets of moderate reps with fairly short rest intervals) substantially increases post-exercise anabolic hormonal levels. What is less clear is whether these transient hormonal spikes actually play a role in the growth process. Evicence is conflicting and there are large gaps in the literature making it difficult to draw firm conclusions on the topic. I have a review paper just published-ahead-of-print that specifically addresses this topic; I’ll have more to say about it soon. Stay tuned…
Summing up, there is compelling evidence that metabolic stress can serve to augment muscle growth. Although we have yet to fully understand precisely how this occurs, it would appear that a combination of factors detailed above are involved in the process. Note that these mechanisms remain largely theoretical at this time, and there may well be others that have not yet been determined.
So how can you use this information? From a practical standpoint, metabolic stress is heightened during resistance training protocols that involve moderate to higher repetitions and fairly short rest intervals. This is typical of the common “bodybuilding-style” method of training and if your goal is to maximize hypertrophy, it appears prudent to include such training as a primary component of your routine. What is not clear as yet, however, is whether metabolic stress provides an additive benefit over-and-above what can be achieved by simply training with very heavy loads. My lab will be exploring this topic over the coming months and I hope to be able to provide some answers in the near future. Stay tuned!
Check out the T-Nation article I wrote with my good friend and colleague Bret Contreras titled, Why Bodybuilders are More Jacked Than Powerlifters. We really worked hard to provide an evidence-based evaluation of the topic. Hope you enjoy it!
I just received word that my review paper, “The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training” will be published in the October issue of the Journal of Strength and Conditioning Research. The abstract has been indexed in Medline at the link below:
It really is sad to see what female bodybuilding has become. Back in the 1980’s, when female bodybuilding first became a professional sport, the competitors looked nothing like the women portrayed in the video. They were toned and fit. They had physiques that other women aspired to. Their bodies appeared healthy and strong and feminine.
In case you find this hard to believe, check out the photo to the left of Rachel McLish. Rachel was the winner of the first-ever IFBB Ms. Olypmia bodybuilding contest. She epitomized the look that female bodybuilders tried to replicate. At the same time, she set a terrific example for women who simply wanted to improve their physiques, proving it was possible to develop muscle while still retaining femininity. It inspired a legion of women to get into the gym, to get into shape, to get healthier. This was the heyday of the sport. Unfortunately, it is a heyday that is long gone.
Somewhere along the way, the sport of female bodybuilding got lost. Somehow it devolved into a bizarro world of she-hulks whose gender often cannot be differentiated. The goal of today’s competitors is to maximize muscle mass without any concern for retaining even the slightest semblance of femininity. Alarmingly, this “bigger is better” mentality is pursued at virtually any cost. After viewing the video you’ll see what I mean.
It’s ironic that the competitors in the video are shown complaining about the lack of prize money. Really now, what do they expect? Professional female bodybuilding has been relegated to an ultra-fringe sport. Let’s face it, the vast majority of the population simply doesn’t want to see a stage full of massively muscled women with facial hair and cro-magnon features posing down against one another. Even the most prominent female bodybuilding competitions can’t attract sufficient interest from fans to offset promotional costs. This has forced promoters to attach female bodybuilding cards along with figure and fitness competitions in order to make the financials work. The money just isn’t there for the competitors. Sad but true.
The most disturbing part of all this is that it has given some women the false impression that lifting intensely will somehow make them look like the current crop of female bodybuilders. Rest assured, hippos will fly before that happens. As depicted in the video, professional female bodybuilders take an abundance of performance enhancing substances to bulk up their physiques. And steroids are just the tip of the growth-promoting iceberg. IGF-1, HGH, thyroid hormone, insulin, clenbuterol…the list of substances these women use goes on and on. Take away the performance enhancers and their physiques would look radically different. In fact, without supplemental help, most women cannot even come close to achieving the muscularity displayed by Rachel McLish. In addition to an extreme training regimen, she had terrific genetics that allowed her to develop her award-winning shape. Only a fraction of the population will possess similar genetics–and if you’re one of the lucky ones, give a big thanks to mom and dad!
Bottom line: Don’t worry about bulking up like a female bodybuilder. It simply isn’t possible. Lifting weights will in no way detract from a woman’s femininity. On the contrary, it will help to enhance feminine curves and shape, reduce body fat, and ultimately produce a strong, fit-looking physique. Lift regularly and lift intensely. You’ll be extremely pleased with the results.
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