Training for maximal muscle growth – is heavy low/medium rep really the best way to go?

HighOrLowReps

I. High Reps vs. Low Reps 

Gym. Handsome man during workoutAre you one of those old school gym rats who believe heavy and low 6-10 rep resistance training the best stimulus for muscle growth? If so, you’re not alone. Many of us (yours truly included, so I’m not pointing any fingers) believe that the best stimulus for muscle growth is heavy lifting in the 6-10 rep range. However, recent scientific findings show that the classical heavy and low 6-10 rep training might not be the best way to induce muscle anabolism…

More reps might be better…

The classic weight lifting recommendation for building muscle is to lift relatively heavy (over 70% of 1RM), or within the 6-10 rep range 1,2. However, a recent study has shown that a training mode with lower weight and higher reps actually is more effective at inducing muscle anabolism and muscle growth 3.

This study had subjects perform 4 sets of leg extension at different loads and volumes (reps):

90% of 1RM to failure: corresponding to 180 lb for 5 reps (90 FAIL)

30% of RM to failure: corresponding to 62 lb/24 reps (30 FAIL)

30% of RM with a total work output similar to the 90% 1RM test: corresponding to 62lb for 14 reps

The scientists measured myofibrillar protein synthesis (the type of muscle protein synthesis that makes the muscles grow) and several anabolic signalling pathways in the trained muscles.

This is the first study to show that low-load high volume resistance exercise (30FAIL) is more effective at increasing muscle protein synthesis than high-load low volume resistance exercise (90FAIL). Specifically, the 30FAIL protocol induced similar increases in myofibrillar protein synthesis to that induced by the 90FAIL protocol at 4 h post-exercise but this response was sustained at 24 h only in 30FAIL protocol. The 30FAIL protocol also stimulated the anabolic signalling pathways to a greater degree than the other exercise modes.

What Does This Mean?
Gym. Handsome man during workoutThis finding counters previous recommendations that heavy loads (i.e., high intensity) are necessary to maximally stimulate muscle protein synthesis 1,2,4,5. It is now apparent that the extent of muscle protein synthesis after resistance exercise is not entirely load dependent, but is also related to exercise volume (that is, number of reps in this case). Thus, the total volume of contractions (number of reps), independent of load (intensity) apparently results in full motor unit activation and muscle fiber recruitment

Now, probably you’re thinking “am I supposed to start lifting like a chick” to build muscle? I want to point out that this study only investigated the effect of one bout of resistance exercise, comprising four sets) on muscle (myofibrillar) protein synthesis. In order to get a definite answer, long-term training studies need to be conducted. According to a personal communication with the head researcher 6, one such training study has been done and is now awaiting publication. With the reply “we are very confident in the short-term data”, at least I will start to throw in some high rep sets here and there in my training program. But in order for this to work, you have to train until complete failure. No sissies!

II. Muscle Growth with High Rep Training – Has Time Come to Challenge Our Egos? 

In the previous section I reported the controversial results of a study that compared the muscle (myofibrillar) protein synthetic response of a traditional “bodybuilding” high-load low rep workout (90FAIL) to a higher rep low load workout (30FAIL), both taken to failure 1.

The workout with higher rep lower load sets (30FAIL) was equally effective in stimulating muscle (myofibrillar) protein synthesis as a workout with low rep high load sets (90FAIL) 1. But more notably, the high-rep low load workout (30FAIL) resulted in a more prolonged muscle protein synthetic response and a greater elevation of muscle protein synthesis rates than the low rep high load workout (90FAIL) 24 hours after exercise, and also induced a greater stimulation of anabolic signalling pathways 1.

However, this study only measured the effects of one single workout bout. This doesn’t tell us whether higher rep sets would lead to long term increases in muscle mass, which is what we are ultimately interested in. Well, the same research group just published an actual 10 week training study 2 to find the answer this nerve-itching question….

Training program

The subjects in this study 2 were healthy young men (21 years old, 5ft 7in tall, 162 lb), who were recreationally active with no formal weight-lifting experience or regular weight-lifting activity over the last year. The training program consisted of unilateral knee extension training. Each leg was randomly assigned to one of three workouts:

1) one set performed to failure at 80% of 1RM (80%-1) – 8-12 reps
2) three sets performed to failure at 80% of 1RM (80%-3) – 8-12 reps
3) three sets performed to failure at 30% of 1RM (30%-3) – 20-30 reps

While the previous single workout study used an intensity of 90% of 1RM 1, in this training study the researchers chose 80% of 1RM, because this is touted as being optimal for muscle grown. Also, training at 90% of 1RM non-stop for 10 weeks would be pretty though and not representative of a typical muscle growth training program.

Each participant trained both legs and was therefore assigned to two of the three possible training conditions. Immediately after each training session subjects consumed a high quality protein (PowerBar Protein Plus, 360 kcal, 3.5g leucine 30g protein, 33g carbohydrate, 11g fat; Nestle Nutrition) in conjunction with 300ml of water to standardize the post-exercise meal and maximize training adaptations.

Before and after the training program, whole muscle volume was measured (using MRI, magnetic resonance imaging) and changes in muscle fiber area were determined. Knee extension performance was measured by 1RM, maximal voluntary isometric contraction (MVC), rate of isometric force development (RFD) and peak power. Changes in anabolic sinaling were also measured.

Results: Muscle Growth

After 10 weeks of training, the quadriceps muscle volume (indicating muscle growth) increased significantly in all groups. Also, the type I and type II muscle fiber area increased with all training conditions, with no significant between group differences.

Muscle Function

Gym. Handsome man during workoutAfter the training period, all conditions significantly increased 1RM strength. However, the increase in 1RM strength was greater in the 80%-1 and 80%-3 conditions compared to the 30%-3 condition.

MVC (maximal voluntary isometric contraction) force, knee extension maximal power output and RFD (rate of isometric force development) increased in all conditions with no between condition differences. The total work that could be completed at 30% of the subject’s 1RM also increased, with no differences between conditions.

The total work that could be completed at 80% of the subject’s 1RM increased in all groups. The magnitude of the increase was significantly less in the 30%-3 condition compared to the other conditions.

The number of repetitions that could be performed with 80% of current 1RM increased in all groups, with no between condition differences in the magnitude of the increase:

Pre-training

30%-3: 10 reps
80%-1: 10 reps
80%-3: 11 reps

Post-training
30%-3: 12 reps
80%-1: 13 reps
80%-3: 12 reps

Not surprisingly, muscle endurance (indicated by the number of repetitions that could be performed with 30% of 1RM) increased only in the 30%-3 condition.

It was also found that anabolic signaling (p70S6K activation) was activated 1 hour post-workout in the 80%-3 and 80%-1 conditions, but not in the 30%-3. However, the previous single workout study showed that the 30%-3 did activate anabolic signaling 4 hour post-workout (no 4 hour measurement was done in this training study).

Conclusions

Gym. Handsome man during workoutSo what’s the take home from this groundbreaking study and its predecessor?

First, it refutes the traditional recommendation that heavier loading, in the range of 6-11 reps to failure is the optimal (and only!) way to maximize muscle hypertrophy 3 , 4. In a heavily cited study, eight weeks of training in a 20-28 repetition range did not elicit muscle growth despite increases in the number of repetitions that could be completed with 60% of 1RM 4 . However, in a subsequent study which employed the same training method, equivalent muscle growth was found in high and low load training groups 5 . It is often claimed 3, 4 that high training loads are necessary to induce muscle growth because they cause full muscle fiber recruitment and activation of type II muscle fibers, which have potential to increase in size more than type I muscle fibers 6. However, this statement is only accurate during a single repetition, since the well known size principle of motor unit activation states that motor units are recruited in an orderly fashion from smallest to largest with increasing requirement for force generation 7, 8. Thus, it is true that one single contraction performed at 30% 1RM will recruit less muscle than a single contraction performed at 80% of 1RM. However, when a sub-maximal contraction is sustained, motor units that were initially recruited will fatigue (produce less force) or cease firing completely, necessitating the recruitment of additional motor units to sustain force generation 9. In this way, as repetitions at lighter loads are repeated to failure, near maximal motor unit recruitment will be achieved 10. Thus, lighter loads lifted to the point of failure would result in a similar amount of muscle fiber activation as compared to heavier loads lifted to failure 7, 11.

Second, although training load did not impact the magnitude of the hypertrophic response (nor maximal voluntary contraction strength, maximal instantaneous power output, and rate of force development), it did have a clear impact on max strength gains. Both the 80%-1 and 80%-3 conditions resulted in a larger increase in 1RM strength compared to the 30%-3. Thus, training with heavy loads (and lower reps) is still necessary to maximize gains in 1RM strength, because strength gains are due not only to muscle growth but also neural adaptations that are only induced by heavy lifting 12. This is important to remember if you are a power or weight lifter, but not directly relevant for bodybuilders or folks who lift weights with the goal to gain muscle.

Finally, it shows that heavy and light relative loads lifted until the point of failure result in a different time course of anabolic signaling, with p70S6K activation occurring later after exercise with light compared to heavy relative loads. It is possible that a training program that elicits increases in anabolic signaling at different time points, might induce a larger muscle growth response than a training program that constantly activate anabolic signaling either early or late post-workout. There are also many other anabolic signaling pathways that are possibly responsive to different weight lifting loads 5. How different training program manipulations affect these molecular level anabolic mechanisms is unknown and certainly warrants further study.

So bottom line; if you are looking to build muscle, don’t get stuck in the 6-10 rep range. Break out of your ego’s comfort zone. Just because you’re lifting lighter doesn’t mean you are “weaker”. So my advice is to spice your traditional 6-10 or 6-12 rep ranges with pump and burn sensation inducing higher rep ranges. In addition to avoiding injuries (which is common with constant heavy lifting), training with strict form in rep ranges in the range 20-30 to failure will nicely chock your muscles and make for a nice workout variety. And as we all know, workout variety and training periodization is essential for performance progress and continued muscle growth 13 , 14.

III. Is There a Place for High-Rep Sets in Serious Muscle Building Training Programs? 

Gym. Handsome man during workoutNow I will show some examples of how high-rep sets can be implemented in a serious weight lifting program, and look at the results of some studies that have investigated this.

Periodized weight training and training variety – a necessary strategy for continued progress

I will save an in-depth discussion on periodized weight training for a separate article. The take home from studies on periodized weight training is that training periodization, or variation, is key for breaking through training plateaus and for making continued progress in both strength, power and muscle growth 1. Benefits with periodized weight training have been seen in both beginners 1-4 and experienced athletes 1, 2, 5-9, but it is especially critical for advanced weight lifters, bodybuilders and other athletes.

Training periodization can be accomplished in many ways; the training variables that are most commonly manipulated are intensity (weight lifted and number of repetitions), number of sets, rest between sets, and lifting speed. In this article I will cover training intensity and lifting speed, since these training variables are directly related; the slower you lift the lighter the weights you can move, and vice versa.

High-rep finishing sets after heavy, high intensity workouts in a periodized training program – how does it affect gains in muscle mass and strength?

An interesting study investigated muscular adaptations to a combination of high- and low-intensity resistance exercise in a periodized training program 4.

The following 3 different types of workouts were tested:

– Hypertrophy (classic muscle building)
9 sets of medium intensity (10 repetition maximum [RM]) short inter-set rest period (30 s) with progressively decreasing load.

– Strength
5 sets of a high-intensity (90% of 1RM) and low-repetition exercise.

– Combination
1 set of low-intensity and high-repetition exercise added immediately after the last (5th) set in the strength-type regimen.

The hypertrophy type phase consisted of nine sets at 80–40% of 1RM. Each workout was divided into three parts with three sets each, and the rest periods between sets and parts were 30 seconds and 3 minutes, respectively. In each part, the intensity was gradually lowered set-by-set (multi-poundage or descending set system). The diagrams below outline the training periodization, and the workout protocol in each phase.

workout-types

Workout Types

The subjects were young men (20-23 years) with a couple of months of recreational resistance training experience, but they had not taken part in any regular training program for at least 6 months prior to the study.

Before the start of the 10 week training program, acute changes in blood levels of growth hormone (GH) were measured after one bout single of each workout type, using leg extension. As illustrated in figure 2, there were significant differences in post-exercise increases in GH levels: hypertrophy-type > combi-type > strength-type.

Next, the long-term effects of a periodized training protocol with these different types of workouts was conducted. The subjects were assigned to either a hypertrophy/combi (HC) or hypertrophy/strength (HS) group and performed leg press and extension exercises twice a week for 10 weeks.

During the first 6 weeks, both groups used the hypertrophy-type training to gain muscular size.

During the subsequent 4 weeks, the HC group performed combi-type training, and the HS group performed strength-type training.

Muscular strength, endurance, and cross sectional area (muscle size) were examined.
After the initial 6 weeks, no significant between group differences was seen in the percentage changes in any of these outcomes.

However, after the subsequent 4 weeks, 1RM of leg press and muscular endurance of leg extension showed significantly larger increases in the HC group than in the HS group. In addition, increases in muscle growth (cross sectional area) after this period also tended to be larger in the HC group than in the HS group. It was also found that adding low-intensity high-repetition set didn’t interfere with neuromuscular adaptations 4.
Lifting speed and time under tension – another variable to consider in high-rep sets

High-rep sets differ from low-rep sets in that they allow more control of lifting (repetition) speed, due to the lower weight lifted. And lifting speed deserves way more attention than it has been getting…

Lifting speed is important because it determines time under muscle tension, which is the amount of time muscles must contract to complete a set. According to the most successful strength coach in the world, Charles Poliquin, to develop maximum muscle mass, the muscles should contract 20-70 seconds during a set 10.

An interesting recent study compared the effects of different lifting speeds on synthesis of different muscle protein fractions 11. The subjects (recreationally resistance-trained young men) did an exercise bout consisting of 3 sets of unilateral leg extension (one leg lifting slowly, the other fast), at 30% 1RM, with 2 min rest between sets:

Slow lifting speed: 6 seconds up and 6 seconds down, no pauses until failure

Fast lifting speed: 1 second up and 1 second down, no pauses

The fast lifting speed condition was matched to the slow condition for contraction volume (meaning that the leg performed an identical number of reps at the same load), but not to failure.

Participants ingested 20 g whey protein immediately after the exercise bout. The number of repetitions performed was 12, 7 and 6 for set 1, 2 and 3. As planned, the muscle time under tension (measured in seconds) was greater for each set in the slow condition compared to the fast:

Slow lifting speed time under tension: set 1 – 144 s (12×12); set 2 -84 s (12×7) and set 3 – 72 s (12×6)

Fast lifting speed time under tension: set 1 – 24 s (2×12); set 2 -14 s (2×7) and set 3 – 12 s (2×6)

The interesting finding in this study was that myofibrillar protein synthetic rate was about 30% higher in after the slow lifting speed bout versus the fast lifting speed bout after 24-30 h recovery, and correlated to p70S6K phosphorylation (which is a marker for anabolism and hypertrophy 12). The slow lifting speed bout also significantly increased both sarcoplasmic and mitochondrial protein synthesis rate 6 hours post-exercise, compared to the fast lifting speed bout.

A slightly faster lifting speed than used in this study, 3 s up and 3 s down (this is still slower than the usual 1 s up – 1 s down), with a slightly heavier load (around 40-50% of max strength) would be more anabolic towards the myofibrillar fraction (which is the muscle protein fraction that is responsible for muscle growth) 13. This agrees nicely with Poliquin’s suggestion that muscles should contract 20-70 seconds during a set to develop maximum muscle mass.

Another study compared a slow lifting speed of 3 seconds up and 3 seconds down at an intensity of 40% 1RM to failure, with a fast lifting speed of 1 second up and 1 second down at an intensity of 80% 1RM to failure, in 5 sets of leg extension 14. The subjects were heavy-resistance exercise trained young men. A striking finding in this study was that the slow lifting speed bout resulted in almost a 3 fold higher elevation in free testosterone than the fast lifting speed bout 14.

It has also been shown that low-intensity exercises with different slow lifting speeds on the up (concentric) and down (eccentric) phases of contractions (3 s up – 3 s down, 5 s up – 1 s down, 1 s up – 5 s down) all significantly result in greater GH elevation compared to fast lifting speeds (1 s up – 1 s down), regardless of the time to complete up and down actions 15.

Finally, there are indications that going faster on the lowering (eccentric) part of contractions than the lifting (concentric) part, leads to greater hypertrophy and strength gains than slow lengthening contractions 16.

Practical Implications

Gym. Handsome man during workoutOki, let try to make sense out of all this…

The above mentioned studies, in conjunction with the findings that high-rep training is as effective as the traditional medium rep training for muscle growth (as outlined in part 1 and 2), underscore the effectiveness of incorporating lighter higher rep sets with slower lifting speeds into your workouts for muscle growth.

In a periodized training program, adding some light high reppers to the end of heavy lifting sets actually increases strength more than just doing the heavy lifting sets alone. However, this might only apply to novice trainers. In recreationally resistance-trained men, light high reppers, especially when performed with a slow lifting speed, have been shown to stimulate muscle growth. It is not necessary to follow that classic linear periodization model where one trains in a specific way for several weeks. Actually, making program alterations on a daily basis is more effective in eliciting strength gains than doing so every 4 weeks 17. The increase in exercise induced elevations of GH seen with lighter high rep sets done with a slow lifting speed is especially interesting for you if your goal is to lose fat, since GH plays a key role in metabolism and boosts fat burning and energy expenditure18-22.

To add variety to your typical workouts, doing lighter high rep sets with a slow lifting speed, especially on the up (concentric) part of the contractions, not only markedly increases exercise induced elevations GH and free testosterone, but also leads to greater hypertrophy and strength gains. This can be explained by a greater muscle time under tension, which increases muscle protein synthesis. For maximum muscle mass development, aim for sets that keep your muscles contracted at least contract 20-70 seconds.

Ok, here’s the final exam question:

– What’s the difference between an exercise novice, old ND fragile lady who does 30 rep sets, and a muscular bodybuilder who does 30 rep sets?

Answer:

The old lady does light high rep sets in order to practice correct exercise form, develop basic conditioning, and avoid injuries. The muscular bodybuilder does light high rep sets in order to add variety to his relatively intense training program and thereby get muscle stimulus from a new type exercise stress, which is necessary for continued training progress.

Even though both the old lady and the muscular bodybuilder might periodically be working out at the same relative intensity (that is, the same percentage of their respective 1RM), the bodybuilder will of course be moving much heavier weight than the old lady because his maximal strength is so much higher. Hey guys, remember that when your egos start acting up!

When looking at bodybuilders and other athletes it’s important to keep in mind that the type of training they did in the past to get where they are in the present isn’t necessarily the best for taking their physiques and performance to the next level. Training variety is essential for continued physical (and mental!) development.

Bottom line, lighter high rep sets with slow lifting speeds, when taken to failure, are not a waste of time in the gym, like many bodybuilders and strength athletes think. To the contrary, lighter high rep sets with slow lifting speeds add two new training variables to your workout, which can help you to break through training plateaus and boredom that arise from constantly doing the same thing in the gym. Thereby, high reppers and sets with slower lifting speeds will help ensure continuous training progress and propel you towards your weight lifting goals.


Monica-Mollica-steakAbout the Author
Monica Mollica
holds a Master Degree in Nutrition from the University of Stockholm and Karolinska Institue, Sweden. She has also done PhD level course work at renowned Baylor University, TX.

Monica is a medical writer and clinical website developer. Being a fitness athlete herself, she is also sharing her hands-on experience by offering nutrition & health consultations, and body transformation coaching.

Having lost her father in a lifestyle-induced sudden heart attack at an age of 48, she is very passionate about health promotion and specializes in preventive medicine.

Monica is currently in the process of writing a book on testosterone, covering health related issues for both men and women. You can visit her website at www.Lean.Fitness.

You can follow Monica here:
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References (Part 1):

1. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Medicine and science in sports and exercise. Mar 2009;41(3):687-708.
2. Kraemer WJ, Fleck SJ. Optimizing Strenght Training: Designing Nonlinear Periodization Workouts: Human Kinetics; 2007.
3. Burd NA, West DW, Staples AW, et al. Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men. PloS one. 2010;5(8):e12033.
4. Campos GE, Luecke TJ, Wendeln HK, et al. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. European journal of applied physiology. Nov 2002;88(1-2):50-60.
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References (Part 2):

1. Burd NA, West DW, Staples AW, et al. Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men. PloS one. 2010;5(8):e12033.
2. Mitchell CJ, Churchward-Venne TA, West DD, et al. Resistance exercise load does not determine training-mediated hypertrophic gains in young men. J Appl Physiol. 2012.
3. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Medicine and science in sports and exercise. 2009;41(3):687-708.
4. Campos GE, Luecke TJ, Wendeln HK, et al. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. European journal of applied physiology. 2002;88(1-2):50-60.
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References (Part 3):

1. Kraemer WJ, Fleck SJ. Optimizing Strength Training: Designing Nonlinear Periodization Workouts Human Kinetics 2007.
2. Rhea MR, Alderman BL. A meta-analysis of periodized versus nonperiodized strength and power training programs. Research quarterly for exercise and sport. 2004;75(4):413-422.
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11. Burd NA, Andrews RJ, West DW, et al. Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men. The Journal of physiology. 2012;590(Pt 2):351-362.
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