Recently, I collaborated with my friend and colleague, Menno Henselmans, to review the literature on the effects of rest interval length on muscle growth. I'm pleased to report that this review has just been published in the prestigious journal, Sports Medicine. If you're into the science ...
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July 23, 2014
Recently, I collaborated with my friend and colleague, Menno Henselmans, to review the literature on the effects of rest interval length on muscle growth. I’m pleased to report that this review has just been published in the prestigious journal, Sports Medicine. If you’re into the science of hypertrophy, I encourage you to read the paper as we delve into all the relevant research on the topic. In the meantime, here is an overview of the take-aways with practical implications.
General resistance training guidelines recommend that rest intervals should remain relatively short to maximize hypertrophy. In a previous review, The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training I echoed these sentiments, suggesting that rest periods of 60-90 seconds would seemingly provide an optimal balance between mechanical tension and metabolic stress (primary mechanisms in the hypertrophic response) to enhance anabolism. It should be noted, however, that these recommendations were based primarily on a logical extrapolation of mechanistic data; there simply have not been a sufficient number of studies that have investigated the topic in a well-controlled fashion.
In what is the most comprehensive study on the topic to date Ahtiainen et al. found no differences in muscle cross sectional area between 2 versus 5 minute rest periods in a sample of well-trained men. The study had several strengths including a randomized crossover design (which substantially increases statistical power), the inclusion of experienced trainees, and the use of the gold-standard imaging modality, MRI, to measure muscle growth. The one issue here is that the 2-minute rest period employed by the researchers is longer than what is generally advised for hypertrophy-type training. The impact on metabolic stress diminishes with longer rest periods, and this conceivably could have had negatively affected anabolic signaling in this study.
The other study that attempted to investigate the effects of rest interval length on hypertrophy was carried out by Buresh et al, whereby 12 untrained individuals performed their workout with either 1 or 2.5 minutes rest between sets. This study actually showed superior results for hypertrophy in the arms and a trend for greater growth in the legs in the subjects using longer intra-set rest intervals. While these results may seem compelling, it should be noted that muscle thickness was determined by anthropometric means (i.e. surface measurements) which can be quite unreliable and thus compromise accuracy. Further confounding matters is the small number of subjects (only 6 in each group) and the fact that subjects were inexperienced with resistive exercise. Thus, while the findings here are interesting they must be interpreted with caution.
So what practical applications can we derive from the literature? Based on current research, it seems highly doubtful that rest interval length has a substantial effect on muscle growth. Bottom line: It would appear that you can self-select a rest period that allows you to exert the needed effort into your next set without compromising hypertrophic results.
That said, the paucity of controlled studies on the topic make it difficult to draw concrete conclusions. Certainly we know that shortening the duration of rest between sets increases metabolic stress, which is known to stimulate muscle remodeling. We also know that well-trained individuals such as bodybuilders are able to sustain a high percentage of their repetition maximum with rest periods as short as a minute. Could the combination of these factors may provide an additional hypertrophic stimulus — albeit a small effect — over time in well-trained subjects? Could other factors such as increased hypoxia and cell swelling also contribute to such a response?
These are questions that require further research. I’m currently in the process of carrying out a study that will provide relevant answers. I hope to begin data collection before the year is out. Stay tuned.
July 6, 2014
In this post I want to delve into the specifics of a study I recently published in the Journal of Strength and Conditioning Research that investigated muscle activation in two popular hamstrings exercises: the stiff leg deadlift and the lying leg curl. While other studies have evaluated differences between these exercises in activation of the medial hamstrings (semitendinosus and semimembranosus) versus the lateral hamstrings (biceps femoris), our study is unique in that we also looked at activity in the upper and lower aspects of the individual muscles.
My interest in undertaking this work revolves around an emerging body of research showing that, contrary to popular belief, muscle fibers do not necessarily span from origin to insertion. Rather, many muscles are compartmentalized so that fibers terminate intrafascicularly (within the fascicle) with each subdivision innervated by its own nerve branch. This structure provides a mechanism by which different exercises can conceivably target different portions of a given muscle. It just so happens that several studies have shown that the hamstrings muscles are in fact partitioned in a manner that would potentially allow for such regional-specific activation. I thus decided to test this hyptothesis in the lab under controlled conditions.
What We Did
Ten young men were recruited to participate in the study. All of the subjects were experienced with resistance training, defined as lifting at least 3 times per week for a year or more. We employed a counter-balanced design where each subject performed both the stiff-leg deadlift and the leg curl. This design provides a high-degree of statistical power, thereby improving the possibility of detecting a significant difference if one in fact does exist. Testing took place over two sessions. In the first session we tested subject’s 8RM on both exercises. The second session involved assessing activation during performance of the movements at the subject’s 8RM.
Muscle activation was determined by a technique called electromyography (EMG). Electrodes were placed on the upper and lower aspects of the subject’s medial and lateral hamstrings; care was taken in placement to make sure that cross-talk between muscles did not confound results. The subjects then performed one of the exercises followed by a lengthy rest period and then performed the other exercise. The exercises were counterbalanced so that Subject 1 performed the leg curl first, Subject 2 performed the stiff-leg deadlift first, etc. This ensured that the order of performance did not confound results. All sets were performed at the subject’s 8RM to muscular failure.
What We Found
Activation of the upper hamstrings was similar between exercises. Interestingly, however, activation of the lower hamstrings, both medially and laterally, was significantly greater in the lying leg curl. The differences in activation of the lower hamstrings was stark, with the leg curl showing greater lower lateral hamstrings activity of ~170% and lower medial hamstrings activity of ~65% compared to the stiff-leg deadlift. The data for the lateral hamstrings was not unexpected; the short head of the biceps femoris does not cross the hip joint, so a knee-dominant exercise such as the leg curl would necessarily be the only way to directly target this muscle. However, the data for the medial hamstrings was somewhat surprising since both the semitendinosus and semimembranosus are biarticular muscles. Results suggest that the partitioning of these muscles may allow for greater regional-specific activation in their lower aspect.
The findings suggest that performing both a hip-dominant hamstrings exercise (such as the stiff-leg deadlift) and a knee-dominant exercise (such as the leg curl) are beneficial to maximize activation of the muscle complex. Given that muscle hypertrophy is predicated on recruiting as many motor units as possible in the target muscles and achieving high firing rates in these motor units for a sufficient length of time to fully stimulate the fibers, it stands to reason that greater activation achieved should lead to greater regional-specific muscle growth. Several recent studies have in fact shown this to be the case, with non-uniform hypertrophy correlating to the region of greatest muscle activation. However, the evidence to date remains correlational and more research is needed to draw cause-effect conclusions. In the meantime, the present study provides interesting insight into how different exercises elicit different responses in a given muscle and lends support to the potential benefits of varying exercise selection to optimize muscle development.
June 16, 2014
Been a little while since my last blog post. Here’s an update on what’s been going on:
• I just received acceptance from the Journal of Strength and Conditioning Research on study showing that you can target different areas of the hamstrings by varying exercise selection. The study evaluated muscle activation during performance of the stiff legged deadlift and the leg curl. We looked both at activation of the medial hamstrings (semiteninosus and semimembranosus) versus lateral hamstrings (biceps femoris), as well as the upper and lower aspects of the muscle. While previous studies have shown that the medial versus lateral hamstrings can be targeted, this is the first study to document differences in the upper and lower portions. Very interesting findings with novel practical implications. I’ll have lots more to say when the study is officially published, which should be soon.
• The internet has given rise to a legion of arm-chair scientists who have little appreciation for what it actually takes to carry out a research study. The upshot is rampant misinterpretation of data and absurd criticisms about study design, often based solely from reading the abstract. That’s why it’s refreshing to see when someone writes an insightful commentary on a study. Such is the case here, where Lyle McDonald provides an excellent critical analysis of my recent study comparing muscular adaptations in bodybuilding- vs. powerlifting-type training. The write-up shows keen insight into understanding the nuances of research methodology and the ability to draw applicable conclusions from the results. Really well done and worth the read.
• I have a number of speaking engagements coming up in the next few weeks. First, I’ll be at the ISSN Annual Conference in Clearwater Beach, Florida discussion how to periodize a muscle-building routine. Next, I’ll be at the NSCA International Conference in Murcia, Spain speaking on a new paradigm for hypertrophy training based on my recent research. Final stop is the NSCA National Conference in Las Vegas, Nevada where I’ll co-present with the incomparable Alan Aragon on practical applications for nutrient timing. If you’re attending any of these events, make sure to stop by and say hello.
May 24, 2014
You pretty much can’t pick up a fitness magazine these days without seeing an article on “functional fitness.” The promotion of the “functional fitness” concept was basically a reaction to popular bodybuilding-type programs that focused on structuring workouts by muscle groups such as the chest, back, shoulders, and legs. Functional fitness proponents countered that such routines did not address the complex interaction between muscles during human movement, leading to the catch-phrase: “Train movements, not muscles.”
On the surface the premise sounds logical.
In reality it’s a gross oversimplification of motor learning principles.
As I’ve previously written about, functional transfer through exercise exists on a continuum. Bottom line is that we need to stop thinking about exercises as “functional” or “non-functional” and realize that for most practical purposes all exercises can produce functional improvements depending on task requirements and the individual.
In this video, Bret Contreras and I discuss the nuances of functional training. We review the science on the topic, dispel some of the popular myths, and delve into practical applications for exercise selection.
May 20, 2014
A new research study on protein overfeeding is causing a bit of a stir in the fitness community. The study in question, authored by Dr. Jose Antonio et al, evaluated body composition changes in a group of men and women that consumed an additional 800 calories of protein each day (to the tune of more than 5 times the daily RDA for protein!) versus a group consuming a maintenance diet. Here is a brief rundown of the methodology and findings.
A total of 30 resistance-trained subjects (and these subjects would be considered highly trained, with an average lifting experience of almost 9 years) participated in the study: 10 in the control group who were at caloric maintenance, and 20 in the experimental group who ate a caloric surplus, with virtually all of the additional calories consumed in the form of a whey/casein protein powder. Subjects were instructed to maintain their normal resistance training programs, which were not supervised by the researchers. Total calories and macronutrient intake were calculated by self-reported daily food diaries. Body composition was assessed by a BodPod, which uses air displacement plethysmography to estimate fat mass (FM) and fat-free mass (FFM).
After 8 weeks, no statistically significant differences were seen from baseline levels in either group. That said, the high protein group did gain an average of 1.7 kg (3.7 lbs), all in the form of FFM. The food diaries indicated that subjects adhered to the diets as specified by the protocol, and the self-reported volume of training over the course of the study did not change from pre-study levels.
So what’s the controversy here? Well, some have questioned the study’s validity, claiming results violate the First Law of Thermodynamics (i.e. energy is neither created nor destroyed, but rather changed from one form to another). When extrapolated to nutrition, the First Law of Thermodynamics essentially states that the difference between calories ingested versus calories expended will dictate whether weight is gained or lost. Since the subjects in the high-protein group consumed 800 calories over maintenance, it would stand to reason that the subjects who overate should have gained a fairly extensive amount of weight. Using the generally accepted formula that 3500 equates to one pound of fat (which is a fundamentally flawed concept, but that’s a post for another day), total weight gain should have been somewhere in the range of 12 pounds over the course of the 8-week study period.
A closer look at the evidence, however, shows that the results were generally consistent with thermodynamic principles. Here’s why.
First, the thermic effect of food (TEF) for protein is very high. Simply stated, the TEF refers to the amount of calories expended in the digestion and absorption process. Protein has a much higher TEF than the other macronutrients, equating to approximately 30% of total calories. Thus, if you overeat 800 calories of protein, about 240 of these calories will be lost to thermogenesis.
Moreover, overeating results in an increase in a phenomenon called non-exercise activity thermogenesis (NEAT). As the name implies, NEAT refers to the energy expended during everything other than regimented exercise (i.e. fidgeting, maintenance of posture, activities of daily living, etc). A classic study by Levine et al found that subjects who were overfed 1000 calories a day compensated by increasing NEAT by a daily average of ~350 calories. Assuming a somewhat similar response in the Antonio et al study, this would mean that approximately 600 of the 800 extra calories consumed would have been expended via TEF and NEAT.
So we’re left to account for about 200 extra calories a day. Well, it just so happens that the reported weight gain of just over 3 pounds explains this away very nicely. The most interesting thing here is that all of the added weight was attributed to gains in FFM as opposed to body fat. This suggests that overfeeding protein well above levels normally thought to maintain a positive nitrogen balance may in fact have a small effect on enhancing the hypertrophic response to resistance training. Although the study did not provide any insight into potential mechanisms, one possibility is that very high protein intakes may help to suppress protein breakdown. Given that increases in hypertrophy are the result of the difference between protein synthesis and degradation, this hypothesis warrants further study.
I’ve heard a number of people criticize the fact that caloric intake was assessed by self-report. To this end, research does in fact show that self-reported food intake can be quite inaccurate. While certainly this is a valid concern, it should be noted that subjects in the high-protein group reported their dietary intake prior to the study as well as during the intervention. It seems logical to think that if these subjects misreported caloric intake during the study, they also would have done so to a similar extent when reporting their baseline intake. Thus, the net effect would seemingly be a fairly accurate representation of the extra calories consumed over the study period. So while there could be issues related to over-reporting of food intake, the results would seem to suggest that the factors I mentioned above are a more likely explanation.
Bottom line: The study, while intriguing, really serves as pilot data for future exploration into the topic. A big issue here is that the resistance training component was not supervised by the researchers. Thus, there is no way to verify what was actually done by the subjects and, importantly, how hard they actually trained. From what I understand, a follow-up study is already in the works that will address this issue. In the meantime, the take-home message here seems to be that if you intend to overeat (and care about your body composition), make sure the extra calories come from protein-rich foods.
May 16, 2014
CrossFit is perhaps the biggest (relatively) new thing in fitness. With over 7,000 gyms worldwide and more than 10 million participants, it’s an understatement to say that CrossFit is big business.
When it comes to CrossFit training methods, everyone seems to have an opinion. Thing is, opinions are rarely neutral; people invariably either hail it as the ultimate fitness experience or trash it as cultist pseudo-science.
As with most things in life, the truth lies somewhere in between.
Without question, CrossFit has positive attributes. If nothing else, it fosters a sense of camaraderie amongst participants. CrossFitters feel like they’re part of a fitness community. The focus on competition pushes them to be their best. Exercise becomes fun. Not surprisingly, adherence in CrossFit gyms tends to be much better than in traditional resistance training programs. Remember: The best workout routine is the one that you’re able to stick with.
And despite what some claim, there is nothing inherently wrong with the CrossFit training model. Is it going to maximize your muscular strength or hypertrophy? No. But it is a viable strategy for improving overall fitness. Depending on your current fitness level, you’ll generally get stronger and bigger from CrossFitting, and you’ll almost certainly improve your muscular endurance. Moreover, when combined with proper nutritional programming, it can help to expedite the loss of body fat. In other words, for a large segment of the population, the CrossFit model has applicability.
The real “issue” is not with the concept of CrossFit per se, but rather in the way that many facilities carry out its training practices. So let’s not throw the baby out with the bathwater. Here are three ways to take the basic principles of CrossFit and enhance its effectiveness and safety.
• Vary Planes of Movement: The human body is designed to move in three-dimensional space. To facilitate such movement, the musculoskeletal system is able to call upon different muscles based on the directional requirements of a given task. The problem with most CrossFit gyms is that almost all exercises are carried out in the sagittal plane. This ultimately results in strength imbalances between agonist and antagonist muscles that not only has a negative impact on your appearance, but can also hasten the onset of injury. Case in point: I recently conducted a study that investigated muscle activation in the rear delt fly – a transverse plane exercise. Guess which subject was the weakest in this movement? Yep, a CrossFitter. When questioned about his training practices, the subject stated that he never performed any horizontal abduction exercises. The result: poor posterior deltoid development. Here’s the easy fix: adopt a multi-planar approach to training by including exercises for all three cardinal planes (sagittal, frontal and transverse) in your routines. This will help ensure you achieve balance and symmetry between muscle groups, and reduce the possibility of incurring any structural discrepancies.
• Periodize Volume and Intensity of Effort: CrossFit training is generally an all-out endeavor; you go balls-to-the-wall each and every session, pushing yourself until you can’t push any more. Bad idea. Sure, high workout volumes and failure training can help to enhance muscular adaptations. But perpetually testing your physical limits over and over again is destined to lead to an overtrained state. The body simply isn’t made to endure such extreme repetitive efforts. Preliminary work from my lab shows that CrossFitters display a much greater incidence of symptoms related to overtraining compared to those who use traditional lifting practices. They report higher levels of fatigue, reductions in performance, issues with sleeping, and incidences of illness. The upshot is a training plateau and even regression of results. The solution: employ periodization principles so that volume and effort are systematically varied over time. This can include gradually increasing volume throughout the course of a training cycle, incorporating a step-loading approach so that weights get progressively heavier on a week-to-week basis, and/or interspersing “deload” weeks where both the volume and intensity of training are reduced. These types of practices will allow for the necessary restoration and recuperation of the body’s resources, facilitating continued progress.
• Focus on Form : Perhaps the biggest issue with CrossFit training practices is the focus is on doing as much work as possible as quickly as possible any way possible. There’s certainly nothing wrong with trying to pack more exercise into less time; this is a viable strategy for enhancing metabolic adaptations. It’s the “any way possible” aspect that causes problems. Potentially big problems. The lifting technique employed at many CrossFit gyms is nothing short of atrocious. Just check out the above video for proof. It’s therefore no wonder that the incidence of injuries is reported to be high amongst CrossFitters. The solution here should be obvious; don’t sacrifice proper form at the expense of exercise quantity. Make sure you have the technique to each exercise down pat so that it is ingrained in your subconscious. If necessary, regress in your exercises before you progress. This is particularly true with complex movements such as the Olympic lifts, where the potential for injury is high. Remember that safety is paramount to any routine; an injury is bound to derail your efforts.
April 18, 2014
Several months ago I wrote a blog post called A Dozen Must-Read Fitness Blogs. The post highlighted a number of blogs that I felt consistently put out great content on exercise and sports nutrition.
Recently, someone commented on the post asking why I didn’t include any blogs written by women. Hadn’t considered this point, but after giving it some thought I realized she was right! It was an oversight that needed to be addressed. Not that gender should make a difference when reading a blog — it’s the quality of course that counts regardless of who writes the post — but it’s nevertheless necessary to give credit where credit is due. Importantly, resistance training for women is an area that is still under-appreciated; the more we can do to make gals realize they need to embrace the iron, the better.
So I’m dedicating this post to feature some truly terrific female fitness pros and their respective blogs. When it comes to fitness, these gals get it. They’re not out there preaching that women should do endless reps with pink dumbbells and follow starvation diets. Quite the opposite, actually. They each have their own niche, but their philosophies are grounded in science and supplemented with a whole lot of good-old-fashioned in-the-trenches experience.
So without further ado, and in no particular, here are five must-read fitness blogs written by women for women (although most guys can certainly pick up a few pointers here as well). As with my previous post, this is by no means a comprehensive list. There are certainly a large number of other female bloggers that I’ve no doubt excluded and will look to cover in a follow-up blog.
• Jen Sinkler: Jen is a former rugby player turned fitness editor. She recently gave up her gig as the head honcho at Experience Life magazine to freelance at a number of the major women’s fitness mags and train clients one-on-one. Her blog is decidedly no-fluff. She focuses primarily on the performance-based aspects of lifting as opposed to training for aesthetics (although the two are not mutually exclusive). Articles are eclectic and range from areas as diverse as kettlebells to cycle circuits to biofeedback. Lots of good stuff.
• Molly Galbraith: Besides being one of the most down-to-earth individuals you’d ever want to meet, Molly is a true fitness pro. She was co-owner of a gym with Jim Laird where she specialized in working with female clients before recently stepping away to pursue online coaching and focus on maintaining her blog. Although the blog delves into a number of fitness topics, Molly’s focus is on helping women with body image issues. Her blogs are often very personal as she writes about her own struggles with body image and her journey to self-satisfaction through fitness. Moly is also co-founder of another excellent female-oriented blog, Girls Gone Strong that should be bookmarked for reading.
• Lift Like A Girl: This blog is written by Nia Shanks. Nia has a degree in exercise science and her in-depth knowledge of resistance exercise shows in her writings. Nia’s focus is on time-efficient workouts, particularly involving strength-based heavy-lifting routines. She covers aspects related to programming, technique and mindset. Some good nutritional articles as well. Lots of interesting reading. Make sure to watch her moonwalk!
• Flawless Fitness: This is Melody Schoenfeld’s blog. Full disclosure: Melody is in fact my sister. But before you claim nepotism, give her blog a read. Melody got her start as a trainer working in my gym back in the 90’s, then moved out to California to open her own facility. She tips the scales about 100 pounds but can out-lift a lot of guys (she holds several state powerlifting records). Her blog covers a wide range of topics. She’s big on kettlebells and holds certs as a master KB instructor. But she also gets into some cool alternative tools such as Indian clubs and even a medieval fighting implement called a mace.
• Stumptuous.com: This is Krista Scott Dixon’s blog. Krista can stake claim to being the original hard-core female fitness blogger and no doubt inspired many of the women on this list. She was churning out cutting-edge fitness articles around the turn of the century, telling women they should be squatting instead of performing a gazillion leg lifts. Her no-nonsense tone is refreshing, and she’s got a great sense of humor that makes her posts fun to read. Unfortunately, it seems Krista doesn’t post much anymore. The good news is that there is a ton of content on her blog that will keep you busy reading for weeks.
April 11, 2014
I’m stoked to announce that my dissertation study, Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men, was just published ahead-of-print in the Journal of Strength and Conditioning Research. I had actually devised the protocol during my master’s degree course in research methods back in 2008. The study I ultimately carried out had some different wrinkles than the one originally proposed, but overall the essence remained the same. Most importantly, it investigated a topic that’s been debated for many years: What are the differences in muscular adaptations (strength and hypertrophy) between bodybuilding- vs powerlifting-type training programs? Here is an overview of the study and a discussion on its practical implications.
20 well-trained subjects (minimum of 1 year resistance training experience working out at least 3 days/week) were recruited to participate in the study. Subjects were randomly assigned to one of two groups: A hypertrophy group (HT) that performed a bodybuilding style routine or a strength group (ST) that performed a powerlifting-style routine. The HT protocol was a split routine where each muscle was worked once per week with 3 exercises per session, performing 3 sets of 10 reps and resting for 90 seconds. The ST protocol was a total body routine where each muscle was worked 3 times per week with 1 exercise per session, performing 7 sets of 3 reps. The volume load (sets x reps x load) was equated so each group essentially lifted about the same amount of total weight per week. Training was carried out over 8 weeks. All sets were performed to the point of momentary concentric muscular failure.
Strength was measured by 1RM in the squat and bench press. Muscle thickness of the biceps was measured with ultrasound. Testing was carried out pre- and post-study, and results were then compared between groups to assess differences in strength and hypertrophy.
3 of the subjects dropped out of the study before completion leaving 17 subjects for analysis (9 in the HT group, 8 in the ST group). Both groups significantly increased biceps muscle thickness by ~13% with no differences seen between groups. Both groups also significantly increased 1RM strength, but the ST group had greater increases in the bench press and showed a trend for greater increases in the squat.
On the surface, the study showed that muscle hypertrophy is similar between powerlifting and bodybuilding type routines provided that volume is equated between protocols. Moreover, the study showed that maximal strength is slightly greater in a powerlifting protocol. This could lead to the conclusion that if your goal is hypertrophy then it doesn’t matter what rep range you use (at least in the heavy to moderately-heavy range) as long as you perform equal volumes, but that maximizing strength requires lifting very heavy weights. From a mechanistic standpoint with respect to muscle hypertrophy, the study suggests that either 1) the increased mechanical tension in the ST group was offset by the greater metabolic stress in the HT group on a volume-equated basis or, 2) there is a threshold for mechanical tension and once the threshold is reached, it doesn’t matter as long as the stimulus is maintained for similar timeframes. With respect to strength, this would suggest that neural factors related to training are still relevant in well-trained individuals, and that using very heavy weights does indeed have a greater transfer to maximal lifts compared to moderate intensity loads.
But the devil is often in the details and that is the case here.
First, it is important to point out that total training time in the ST group was 70 minutes while that of the HT group was 17 minutes. So from a time-efficiency standpoint, the bodybuilding-type training produced similar hypertrophy (as well as nearly similar strength increases) in about a quarter of the time as the powerlifting routine. Moreover, exit interviews revealed that those in the ST group were fried by the end of the study. Almost all of them complained of sore joints and general fatigue, and the two dropouts from this group were because of joint-related injury (and these routines were highly supervised with respect to form, so we took every precaution for safety). On the other hand, the HT group all felt they could have worked substantially harder and done more volume.
This brings up an important take-away message: While mechanistically it appears that it does not matter whether heavy or moderately-heavy weights are used for hypertrophy, from an application standpoint it simply isn’t practical to train constantly with the volumes used in this study on multiple body parts. The grinding on the joints and the taxation of the neural system that is involved with repeated performance of very heavy loads ultimately has a negative impact on the lifter; I am certain that if we had continued this program for any longer, most of those in the ST group would have been overtrained and seen performance decrements. If nothing else, these finding reinforce the importance of periodizing programs so that cycles of deloading are interspersed with very heavy loading protocols.
Additionally, realize that only three major muscle groups were worked in the study: the pecs (upper body pushing); the back (upper body pulling) and the thighs. Thus, the HT group could have easily done a couple of extra sets for each muscle group without overtaxing their resources. Although impossible to say for sure, it certainly is plausible that additional work would have enhanced the hypertrophic response in the bodybuilding-style training group. Moreover, the HT group could have performed exercises for other muscle groups, including some targeted work with single joint movements. Working specific muscles (and aspects of muscles) such as the middle and posterior delts, the hamstrings and the calves alone would definitely have benefited overall muscle hypertrophy.
So bottom line: The study indicates that the best approach to building muscle is to perform a combination of heavy and moderately heavy loads. The “hypertrophy range” is applicable from the standpoint that it allows the performance of a greater amount of volume without overtaxing the body’s resources. Adding in loads in the 1-5 RM range can enhance strength (which ultimately allows the use of heavier loads during moderate rep lifting) as well as providing a potent hypertrophic stimulus.
It should be noted that.I made a conscious decision to investigate the two types of routines as lifters usually perform them. Thus, the HT routine was a split routine since the vast majority of bodybuilders train in this fashion, while the ST routine was a total body routine since this is the way most powerlifters train. While staying true to the usual performance gives insight into how muscular adaptations generally play out in everyday practice, they also obscure the ability to attribute results entirely to the set/rep scheme. I will be carrying out a follow up study that seeks to address this issue in the near future. Stay tuned!
March 29, 2014
Admit it. You’ve probably been lured into reading a magazine article with headline such as the one above. These types of claims are the norm rather than the exception in the muscle rags and fitness websites. And for good reason: the promise of a holy grail of workouts that will maximize your muscle development is an enticing prospect to say the least.
Problem is, no such routine exists.
It’s essential to realize that the response to resistance exercise is highly individual. Remember that research simply reports the means (i.e. averages). So if a study reports muscular growth after a given protocol as say 10%, you can bank on the fact that some subjects grew a lot more and some a lot less than 10%. Thus, you can’t simply extrapolate that you, or a client of yours, will achieve similar results to the reported mean.
Nowhere is this better illustrated than in a recent cluster analysis study by Bamman et al.. Sixty-six men and women performed supervised lower body exercise (squats, leg presses, and leg extensions) 3 days a week for 16 weeks. Training was carried out in typical bodybuilding-type fashion that included 3 sets of 8-12 reps for each exercise. At the end of the study, subjects were grouped by their hypertrophic response: The top 17 subjects were considered extreme responders. Their muscular gains averaged ~58%. Pretty awesome, right? The middle 32 subjects were considered moderate responders, with muscular gains averaging ~28%. Still pretty good, although well below the extreme responders. Here’s the kicker: the bottom 17 subjects saw, get this, NO significant gains after 16 weeks or consistent training. Zilch! Again, all subjects performed the exact same program but, as noted, saw widely disparate results. Based on the research, genetic factors are highly responsible for these differences, including the expression of various proteins (such as IGF-1) as well as satellite cell population. Lifestyle factors undoubtedly play a role as well.
Now the fact that people respond differently doesn’t discount that there are certain principles that should be inherent in any routine designed to maximize muscle-building. These include:
• Vary the loading strategies: Using different rep ranges (i.e. heavy, moderate and light) will ensure that you stimulate the full spectrum of muscle fiber types in a fashion that produces maximal growth. Recent work from my lab shows that light loads are suboptimal for recruiting the highest threshold motor units, but they may be superior for targeting the type I (endurance-related) fibers.
• Train with high volumes: There is compelling evidence that a dose-response relationship exists between volume and hypertrophy. Although a single set to failure can produce substantial increases in muscle growth, multiple sets are needed for maximal gains.
• Employ some sort of periodization scheme: This simply means that you need to manipulate variables over time. In particular, volume and training frequency should be varied over the course of training to prevent overtraining. Ideally, volume/frequency should culminate with a relatively short training cycle designed to produce functional overreaching followed immediately by a period of active recovery. This will help promote a supercompensatory response that maximizes muscular gains.
Given these basic tenets, it is essential that you take individual differences into account when designing training programs. There are no cookie-cutter prescriptions for getting big. For those familiar with my book, The M.A.X. Muscle Plan, you’ll know that I reinforce this concept repeatedly throughout the text. That’s why I refer to the book as a “template” for success; optimal benefits can only be achieved by customizing the program to your own personal needs and abilities.
Bottom line: There is no “best” muscle-building program; only a best program for a given individual.
March 8, 2014
Blood flow restriction (BFR) training is an emerging technique that consistently has been shown to improve muscle strength and size in a variety of populations. If you are not familiar with BFR, you can read my recent T-Nation article that details the hows and why’s of the topic. If you’re interested in the research, you can read the review that I co-authored here.
A new BFR study by Luebbers et al. has been creating a lot of buzz. A number of people have emailed me to ask my opinion on the paper, so I figured it was worthy of a blog post.
Briefly, the study was a follow up to a previous study by Yamanaka et al. , who reported significant increases in chest girth, as well as 1RM bench press and squat performance when BFR was combined with heavy resistance training in a group of well-trained college football players. Here are the particulars of the new study followed by my commentary and take home points.
The study used a protocol similar to the investigation carried out by Yamanaka et al. Sixty-two Division 2 football players took part in the study during their off-season from competition. Subjects were randomized into 1 of 4 groups:
• H/S/R Group. This group performed high-intensity training (H) consisting of traditional strength training exercises (bench press, overhead press, power cleans, squats, etc) and auxiliary lifts (bicep curls, triceps extensions, calf raises, and abdominal work). In addition, they performed supplemental lifts (S) at the end of each workout consisting of 4 additional sets of bench press on upper body day and 4 additional sets of squats on lower body day. The supplemental work was carried out under blood flow restriction (R).
• H/S Group. This group performed the exact workout as H/S/R except no BFR was used for the supplemental exercises.
• H Group: This group completed only the basic high-intensity training routine (H). They performed no supplemental exercise with or without BFR.
• M/S/R Group. This group performed only the auxiliary exercises but not the traditional strength training exercises. They also performed supplemental work with BFR at the end of each workout.
The BFR was a “practical” protocol that employed ~3 inch elastic wraps to occlude flow. The load for these exercises was set at 20% 1RM with the first set consisting of 30 reps followed by 3 sets of 20 reps separated by 45 seconds rest. For all groups, the training program employed an upper/lower body split performed 4 days per week for 7 weeks. The split followed a 2-on/1 off, 2-on/2-off format with workouts taking place Monday, Tuesday, Thursday, and Friday.
At the end of the 7 week study period, the group performing the traditional strength training protocol supplemented with BFR (H/S/R) showed significantly greater increases in 1RM squat compared to the other groups but there were no differences in 1 RM bench press between groups nor were there any differences in thigh, chest, or arm girth.
The researchers should be commended for an ambitious study design. They had a fairly large sample size (over 60 subjects) and the 4 groups provided diverse info on a variety of possible program applications. Moreover, the subjects were all well-trained lifters (average of over 7 years resistance training experience), which rules out any confounding issues associated with an initial learning curve and inflated gains from sedentarism.
That said, the study had a number of substantial limitations that cloud the ability to draw relevant conclusions. First and foremost, the use of circumference measurements as a proxy for muscular gains is highly suspect as the technique does not specifically measure muscle tissue in isolated areas of the body. Indeed, imaging techniques such as ultrasound have been shown to detect increases in muscle hypertrophy not seen by measures of girth. Compounding matters, the researchers made no attempt to control for nutrition. Remember, the subjects were college football players in the offseason from competition. To put it mildly, it’s highly unlikely they weighed their food and adhered to a balanced nutritional regimen. Since girth measurements cannot discern between muscle tissue and subcutaneous fat, this certainly could have confounded results.
Another thing that jumped out at me when reading the methodology was the following statement: “All sessions were supervised by the same two primary researchers in order to ensure compliance.” The study had over 60 subjects who trained at one of three times during each training day. That means that there were over 20 subjects training at a given time. How can two researchers adequately supervise all these subjects and ensure that they are training as per protocol? In my lab, I have a dedicated research assistant work with each subject in a training study. They supervise every aspect of the workout protocol – from using proper technique, to exerting sufficient intensity of effort, to making sure that the rest intervals are rigidly upheld. If research assistants did not in fact help out with supervision here, I’d have to question how well subjects actually complied with the protocol.
Finally and importantly, the results don’t make a whole lot of sense. Specifically, how could lower body strength show greater increases with BFR without concomitantly greater increases in hypertrophy? There are two primary mechanisms for strength improvements: an increase in muscle size (there is a direct relationship between muscle cross sectional area and the ability to produce force) and/or an enhancement in neural response. Research indicates that neural enhancement is primarily achieved through the use of heavy loads, particularly in a well-trained population who have transitioned past the initial motor learning stage. Thus, I find it difficult to believe that BFR — which uses very light loads — had a significant impact on neural aspects such as rate coding or synchronization. If strength was significantly increased in the BFR group compared to the non-BFR groups, it would seem that these improvements would have to be due to greater gains in muscle mass.
While this study (as well as the previous study by Yamanka et al.) provides interesting data on the potential use of BFR as an adjunct to traditional resistance training, the aforementioned limitations make it difficult to draw an practical conclusions. Similar studies should be carried out using a validated imaging technique (i.e. MRI, CT, ultrasound, etc) under well-supervised conditions to determine if there are in fact any benefits to combining BFR with heavy loads.