I have personally trained with weights since right before my 16th birthday. As was standard then, and seems still standard now, low repetition training with heavy weights has been the dogma for that entire time as the the ONLY way to build muscle on the body. Yet, among all those years, no matter how careful the form, came persistent nagging injuries and persistent joint pain, both large and small. Around my 28th year of life, and 13 or so years into training, I sustained a bulging disc in my lower back doing a set of squats with weight, for me at the time, I could do only 8 or so times.

This started a train of thought that continually plagued me for the next couple decades: why can’t I train to failure with high reps, use lower weight that presents no real threat to the joint structure of my body, and still gain muscle as long as I continue to increase the reps over time and the weight? It made no sense to me why it wouldn’t, but I was so locked into the flashy big weights I never really gave it a try: mark one for cowardice on that one.

Somewhere in 2006 or so (if my memory serves me correct here) I saw a big hubbub on the bodybuilding.com forums as a poster introduced him as Serge Nubret (hopefully you know him; the man in Pumping Iron who presented the only TRUE risk to Arnold’s reign). After much contention, guffawing, and general abuse to the poster, he confirmed his identity with the overseers of the forum and the real discussion began. Much was discussed, some standard some controversial, but the one topic that stood out in my mind were two things he stated outright that many found interesting in the thread but I don't think to the level I did: he ALWAYS trained with high repetition training and NEVER had an injury. Now that is a fantastic claim for a guy who was in his 70’s at the time of the thread and had trained for DECADES. Never injured? Never did lower reps? Yet, Serge was huge at any age compared to normal men and even to other high level weight trainers at every age he could be compared to his contemporaries (imho, his physique at the time of Pumping Iron, in my humble opinion, is perhaps one of the best the world has seen in any era and may be the pinnacle of human muscular development presented in aesthetic perfection).

And that STILL did not change my training to doing high repetition training. At the time I was in my late 30’s, and my joint structure was weathering some heavy workouts every week quite well. This continued into my early 40s, when with what felt like a fairly rapid drop in energy levels linked to overwork, the ensuing stress and sleep deprivation, and consequent lowered testosterone levels and persistent raised cortisol levels led finally to joints starting to hurt not from injury but from just working out itself (most particularly the rotator cuffs).

I began to experiment with high rep training, found my joints felt better, but I found myself wincing from the heavy lactic acid buildup that was a whole different level of overcoming pain and discomfort that low rep training required. Like a good addict, it gave me an excuse to relapse into low rep training again and I’d be fine a while, as the joints and tendons had apparently healed well while doing the high rep training a while, but sooner or later the nagging pains returned, the aching rotator cuffs, the cracking knees, the pulsating elbows, all of it. I was exasperated: high rep training was taxing as hell, not as ego rewarding, but my joints and tendons felt great; low rep training fulfilled my precious ego, was thrilling to engage in due to the sheer danger it presented at times, but after decades of low rep training, despite form changes and speed of rep changes, it inevitably led to aches and pains beginning anew.

I began to search into high rep training, as I had been wont to do many times the previous years. Before, nothing would come up in a search, but around 2010 I started to see some research start to surface and come up in my searches. A very curious sports scientist, a Mr. Burd, had begun the research I had waited half my life to see.

Oddly, there had been a decent study in 2002 I had failed to notice. Splitting 32 untrained men into 4 groups of varying repetition ranges, it concluded that “Although all three training regimens resulted in similar fiber-type transformations (IIB to IIA), the low to intermediate repetition resistance-training programs induced a greater hypertrophic effect compared to the high repetition regimen.¹ The High Rep group, however, appeared better adapted for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion”. So there was some fiber type transformation that occurs whenever you have significant load in weight training studies (and transformation to fibers meant more for endurance work occur in studies where heavy endurance training is done), I think they wrongly concluded that low repetition training leads to greater muscle hypertrophy gains simply because the testing protocol prevented it. In the experimental design they gave the low reported group 3 minutes rest between sets, but the high repetition group only one minute rest between sets. It is my view that may not be sufficient on a biochemical level, and for the participants themselves the rest time should have been equivalent, as high rep training is exhausting and the lactic acid accumulation can be so intensely painful and fatiguing that further sets would NOT be approached with the same intensity that the low rep trainers had with a three minute rest, therefore diluting any training effect of further sets the high rep training might have had on muscle hypertrophy. The fact ALL rep ranges led to the same fiber-type transformation lends to the idea that ALL rep ranges would experience muscle hypertrophy, and the minimal rest the high rep trainers got is simply poor experimental design in my view and should have been kept as a constant variable across all training groups as it just confounds the results with a variable which was not necessary to vary whatsoever. For the researchers to conclude, “both physical performance and the associated physiological adaptations are linked to the intensity and number of repetitions performed”, seems disingenuous since “intensity” cannot be held constant when rest times vary 3-fold among training groups.

In 2010 occured the study I had waited years for. Our Professor Burd tested low repetition versus high repetition training to failure. Yes, training to failure, the only way to train that really is “progressive resistance training”, where each set is done to failure for the participant, and in my view, done to better the previous performance of the preceding workout. There were three groups in the experiment, but the two we will look at were the train to failure groups: one used 90% of 1 repetition maximum, the other used only 30% of 1 repetition maximum. I love how Burd used such a low weight, as it runs full force into resistance training dogma: “there is no way weight training even to failure with such a low weight will do anything!”. We shall see...

He found astonishing results. For both the 30% and 90% training to failure groups were similar results in several biochemical markers of muscle growth and protein synthesis, but “the increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30 FAIL was greater than 30WM [the third group working out with a standard protocol], with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30 FAIL.” MYO was myofibrillar protein synthesis (the main one we want to see), and MIX was both myofibrillar and sarcoplasmic (less important but still constituent to muscle) protein synthesis. The key here is ONLY in the 30% training to failure group was myofibrillar protein synthesis elevated 24 hours later.² This was a colossal finding, but… our profound Professor Burd needed to confirm if such changes biochemically really translated into muscle hypertrophy, as not all roads in science lead to where you’d hope they would, sadly.

A further clue was done in 2012. It found that though muscle volume was similar in three groups (30% of 1 repetition maximum -3 sets , 80% of 1RM -1 set, and 80% of 1RM -3 sets), that isotonic [fancy term for concentric and eccentric repetitions under resistance] strength gains were greater in the two groups training at 80% of 1 rep max, than the group training at 30% of 1 rep max.³ We are going to see this trend further on: high rep training leads to similar, if slightly less, hypertrophy, but also significantly less strength gains. My view is: so what? What isn’t measured is injury probability, which I’m going to say plummets so low on high rep training that the risk to benefit analysis makes high rep training astoundingly better than low rep training.

Also, in 2012 Burd came out with an interesting paper discussing that what he called “high-intensity contractions” [those contractions done under heavy weight load] were not the only drivers of “resistance exercise-induced changes in muscle protein synthesis rates”.⁴ I will discuss this paper later in an article, but suffice it to say this had been occurring through all the research into muscle hypertrophy: that the picture is far more complex than previously thought, and is largely mediated by an interplay between muscle contraction, time under tension of those contractions, hormonal interactions, and nutritional intake of a whole medley of proteins and fats.

A study in 2012 with untrained female participants was studying slow speed training versus normal speed training ( something I’ll investigate in a later article), but also used subsets of 40-60% 1 rep max and 80-85% 1 rep max (the part we are obviously interested in here).. It concluded basically that normal speed training done at 80-85% of 1-rep max was most effective at provoking a “greater adaptive response”⁵; however, I will contend with these results because they are NOT training to failure, and that is where Burd’s genius lay: lower 1 rep max training (i.e. high rep training) is exhausting and crippling for most people and they will quit long before true failure. I would bet a huge sum of money that the women in this study, had they been experienced trained participants, or been taught to work to true failure, would have seen far greater “adaptive responses”, most especially muscle hypertrophy. It’s these type of badly designed studies that really confuse the issue of high-rep versus low-rep training. We NEED training to failure to see how the body will adapt to significant stress to the skeletal-muscular system.

In 2013, Schoenfeld, another big-wig in this area of study, asked a profound question in the title of a paper he wrote: “Is there a minimum intensity threshold for resistance training-induced hypertrophic adaptations?” In other words, is there some minimum percentage of 1 -rep maximum that has to be used to cause muscle growth? He relates that researchers were beginning to do studies on high rep training using training to failure methods that essentially mimic some studies that were done that used blood flow restriction. Schoenfeld admits that in untrained subjects that this kind of training seems to have effects that may be meaningful even in relation to typical approximately 60% 1 rep max training. However, he states finally that “... whether hypertrophic adaptations can equal that achieved with higher intensity resistance exercise (≤60 % 1RM) remains to be determined. Furthermore, it is not clear as to what, if any, hypertrophic effects are seen with low-intensity exercise in well-trained subjects as experimental studies on the topic in this population are lacking”⁶ This is precisely what has been done since his paper, thankfully.

In 2013, a study was done with older male adults, where the participants were given the leg extension and leg press over 12 weeks and assigned to three groups: a HIGH group (2×10-15 repetitions at 80% of one repetition maximum (1RM)), a LOW group (1×80-100 repetitions at 20% of 1RM), orn alast group, LOW+ (1×60 repetitions at 20% of 1RM, followed by 1×10-20 repetitions at 40% of 1RM). tHough the HIGH group had an advantage from week 5 on with a dynamometer at 240{put angle bubble] (which would indicate a greater power production for maximal exercise), the researchers found similar results in all other areas, including muscle volume. The researchers concluded, “ ... high- and low-resistance exercises ending with muscle failure may be similarly effective for hypertrophy. High-resistance training led to a higher increase in 1RM strength than low-resistance training (20% of 1RM), but this difference disappeared when using a mixed low-resistance protocol in which the resistance was intensified within a single exercise set (40% of 1RM).”⁷ Some things to note in that statement:

In 2015, Schoenfeld conducted a grueling study on eighteen well trained male subjects in 2015. They performed three sets of seven exercises three days week (63 sets a week). This is far too many for this to have been training to failure and nowhere is it stated it is training to failure, so we can assume it was done to discomfort levels for participants. There were two groups for the experiment: 9 trained with high resistance (8-12 repetitions) and nine with low resistance (25-35 repetitions). It isn’t stated, but lets assume the repetitions were based off similar uses of 1 repetition maximums that previous studies had done (80% and 40%). He found that the high resistance low rep group made much more significant advances in peak strength, for both squats (approximately double) and bench press (approximately triple), but “Both HL [high resistance, low rep group] and LL [low resistance, high rep group] conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups.”⁸ Now that is fascinating: you get much greater strength increases with high resistance low rep training, almost embarrassingly so; however, your muscle volume increases for low resistance, high rep training approximately the same. And, again, never talked about, the risk of injury is absurdly lower for low resistance, high rep training.

Of note is something most ego-driven lifters don’t consider; the low resistance, high rep group got a nice increase in muscular endurance whereas the high resistance low rep group actually LOST some of their muscular endurance (oh, you thought the loss of some strength gain was not offset by some advantage to the other side? Silly buffed rabbit). As the researchers stated, “upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively).” I would bet the increase in muscular endurance for squats would be even better, as it involves greater muscular mass and thus greater use of substrates necessary for high rep training and the requisite muscular endurance.

In 2016, a study was performed on untrained adolescents. Perhaps not a group fitting the trained athletes probably reading this, but it’s finding may generalize still to some extent for all trainers. Fitting the teenagers into three groups: a control, a group doing 4-6 reps for 3 sets, and one group doing 12-15 reps for 3 sets. The two training groups trained twice a week for 7 weeks doing bench press and squat. No significant differences were found by the end of the study on any measure.⁹ This study doesn’t help us look at true high rep, low resistance training, but it DOES show that if you insist on training with high resistance, that a rep range of 12-15 should be just as sufficient for your goals at 4-6, a significantly more prone to serious injury rep range.

A truly eye-popping study occurred in 2016. It was even measuring acute hormonal response to training to see if that affected training effect. They took forty-men, all “resistance-trained” [had previous weight training experience of significant length of time] and put them randomly into two groups: one would do 3-50% of 1-rep maximum for 20-25 reps, the other 75-90% of 1RM for 8-12 reps. Thankfully, all sets were done to “volitional failure”, i.e. where participants felt they could not do another rep, i.e. training to failure. This study was extremely thorough in its testing measures, using muscular biopsies (the gold standard for muscular volume increases and muscle fiber type growth and transformations), strength testing, and dual-energy xray absorptiometry scans (i.e., DEXA scan, used to determine bone mass and secondarily muscle volume through standard formulas). They found 1 rep max increased in both groups, with the lower rep trainers achieving a 14 kilogram increase versus the 9 kilogram increase for the high rep trainers. There were no significant differences in muscular hypertrophy nor in the type I and Type II cross sectional areas following the training.¹⁰

This study is key because we see the training to failure we need to TRULY assess differences between low rep and high rep training. Also, we see measure protocols using the best technology possible for such measures: muscular biopsies and DEXA. Training to failure shows what we’ve now seen a few times: same or significantly similar increases in muscular hypertrophy, muscular volume, but less strength increases for the high rep group (but let’s be really clear here: they STILL get strength increases but not as much).

And, my old bugaboo: the high rep trainers are under incredibly less probability of injury compared to the low rep trainers, yet get to have most of the advantages of the low rep group (and as we just saw, get some muscular endurance benefits that the low rep group does not get to enjoy at all, in fact, seem to lose).

Final note on the study: what did they find out about acute hormone changes from training? That it had NO correlation to the training effects. This, however, did NOT look at chronic effects on hormones that continued training could possibly do over time for hard trainers, thus why I advocate phosphatidylserine and acetyl l-carnitine for trainers who like to enjoy frequent training and not incur possibly chronic deleterious effects to testosterone, cortisol, etc.

In 2016 (published electronically in 2014 though, so I don’t think he incorporated the study just discussed), Schoenfeld, produced a meta-analysis of 32 effect sizes and 25 subjects, and looked for studies that “randomised controlled trials to compare the effects of low-load (≤60% 1 repetition maximum [RM]) versus high-load (≥65% 1RM) training in enhancing post-exercise muscular adaptations”. What did he find? He found a trend for muscular hypertrophy in high-loads compared to low-loads (.82 +- 0.17 vs. 0.39 +- 0.17). He concluded that training with loads under 50% 1Rm promoted “substantial increases” on muscle strength and growth, but that a trend was found for high-loads, and that results that didn't’ fit that conclusion was due to a small number of studies on the topic.¹¹ In other words, he is fairly sure of his conclusion and blames the lack of confirmation through actual data will be forthcoming with further studies (“the findings don’t fit my conception I really want to be true”). And, once again, no mention of the possibility of injury being much greater for high-load training. Researchers in this particular area of study never bring this up, possibly from being fully wedded conceptually to high load training as the holy grail of training.

Though far too short of a study for an experiment using weight training, there was one done in 2016 that measures muscular hypertrophy and muscular strength changes on trainers using 30% versus 80% of 1rm maximums. It measured at 2 weeks and 4 weeks into training (absurd, I know). To cut ot the chase, it concluded, “Resistance training to failure at 80 vs. 30% 1RM elicited similar muscle hypertrophy, but only 80% 1RM increased muscle strength.”¹² No mention is made about training to failure, but despite that, we see the same old song we have seen several times: high rep, low resistance training leads to muscular hypertrophy similar to low rep, high resistance training, but with not the same increase to muscular strength, And, of course two things not mentioned: the high rep group would have greater increases in muscular endurance and be at much less risk of injury

Lastly, let’s wrap this up with another meta-analysis by Schoenfeld et al, this time done in 2017. This time, feel, he was much more careful to use studies that had greater similarity of purpose: all were at least 6 weeks or more duration; all sets were performed to “momentary muscular failure” (thank god!), and they had at least one method to measure changes in muscle mass or strength.

Using 21 studies that qualified, he concluded that, “ Gains in 1RM strength were significantly greater in favor of high- vs. low-load training, whereas no significant differences were found for isometric strength between conditions. Changes in measures of muscle hypertrophy were similar between conditions. The findings indicate that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges.”¹³ In layman's’ language: low-rep , high resistance training leads to better strength increases, but both types of training can achieve EQUALLY increases in muscular hypertrophy.

And, not mentioned, but something I will conclude with as my conclusion: farrrrrr less chance of acute, chronic, or catastrophic injury with high rep, low resistance weight training. I will stand by that as the final variable NEVER discussed in even one of these studies that is of such a benefit if you intend to weight train for any length of time in your life that it profoundly skews our results to high-rep, low resistance training to be the key to decades on continued fitness in your life if you intend weight training to be one of the key components of it. Serge Nubret figured this out from carefully and honestly looking at feedback from his own body from working out, and if his claim to being injury free his whole life was true, his amazing physique he kept over DECADES is a living testament to this type of training.

On a different level of observation, if you want to mitigate some of the soreness and other changes ANY kind of intense training incurs, give a look at my articles on phosphatidylserine, Acetyl l-Carnitine, and HMB. I’ve used them for years and truly see their benefits in my own life and the research is there in my articles to give you food for thought as to their effectiveness.