Do post-workout spikes in GH (and testosterone, IGF-1) increase muscle growth?

An ongoing obsession of bodybuilders and strength athletes is boosting growth hormone (GH) levels. This preoccupation extends back to the 1980s when, inspired by the infamous “Life Extension” duo Durk Pearson and Sandy Shaw, bodybuilders gulped down ungodly amounts of the GH-spiking amino acid l-arginine (and, in some instances, l-ornithine) in the hope of experiencing steroid-like muscle growth.

It didn’t work. These amino acids failed to produce the promised anabolic effects and, like so many highly-hyped muscle-building supplements, eventually fell by the wayside (and, like so many highly-hyped nutrition fads, were recently resurrected and marketed to a new generation of suckers, um, pardon me, customers too young to remember the fad’s original failure. In this case, arginine and ornithine have recently been doing the rounds in the form of largely useless pre-workout “nitric oxide boosters”).

In recent times, strength athletes have tried manipulating both their workouts and diets in an attempt to increase GH levels. The two best-known training methods for boosting GH are inclusion of compound multi-joint leg exercises such as squats and the use of short rest periods between sets (60 seconds or less).

As for diet, some strength athletes have been convinced by promoters of low-carbohydrate diets that these regimens will produce marked increases in GH. We’ll discuss the evidence, or complete lack of it, for this contention in Part 2. Today, we’ll take a critical look at the belief that workout-induced spikes of GH and other anabolic hormones result in greater muscle size and strength gains.

Squatting for Upper Body Growth?

Weight training folklore has long held that performing heavy lower body exercises such as squats results in extra muscle growth, not just in your legs but in your upper body as well. According to this theory, by regularly performing heavy squats your chest, shoulder, latissimus and arm exercises will produce more muscle growth than they otherwise would. The reason for this extra muscle growth, so the story goes, is that squats cause your body to pump out greater amounts of GH.

A lot of folks in the Iron Game regard the squats-boost-GH-boosts-upper-body-muscle-growth theory as a sacred tenet, and can readily regale you with tales of how their best whole-body muscle gains were made whilst regularly performing gut-busting squat sessions.

Others think the squat-upper body growth theory is a load of bollocks and maintain they’ve never noticed any difference in upper body growth as a result of regular squatting.

So who’s right?

Gone in Sixty Seconds

The fact that short rest periods (60s or less) produce greater GH spikes than longer rest periods between sets is not in dispute – it has been shown time and time again in controlled studies. Science has also clearly demonstrated that performing heavy leg workouts results in a far greater GH spike than performing workouts comprised solely of exercises for small muscle groups such as the upper arm muscles.

The real question is, do the brief growth hormone spikes that occur in conjunction with weight training workouts actually help to increase muscle growth or strength?

In 2001, a study was published in which 16 young untrained males were assigned to an arm-only training group, or a leg plus arm training group[1]. The study lasted nine weeks, and hormonal responses were tested during the first and last training sessions.

During this time, no difference was seen in resting hormone concentrations between the two groups. However, during the first training session plasma testosterone as well as plasma cortisol increased significantly in the leg+arm training group but not the arm-only group. Plasma GH rose in all exercise tests, except during the last test in the leg+arm group group. However, plasma GH was significantly higher in leg+arm training group than the arm-only group in the first training session.

At the end of the study, isometric (static) arm strength increased to a significantly greater degree in the leg+arm group. This finding is often used as ‘proof’ that training-induced GH and testosterone spikes have a positive effect on training outcomes. However, the leg+arm group started the study with significantly lower isometric arm strength, so this may have been the real factor behind their greater improvement. The fact that there was no difference between the two groups in functional strength gains adds further credence to this contention.

More Recent Research

In 2009, West et al published a study showing marked spikes in GH, testosterone, and IGF-1 after an arm+leg training workout. When the same subjects performed an arm-only workout, no such spikes in these hormones were seen. To see if the acute elevation of anabolic hormones was stimulating greater arm muscle growth in the arm+leg group, the researchers performed muscle biopsies four hours after both workouts. To further boost muscle protein synthesis, twenty-five grams of whey protein was given to the subjects post-workout on both occasions. No differences in muscle protein synthesis were observed between the two workout conditions[2].

These results indicate that acute training-induced hormone spikes have no anabolic effect during the post-workout recovery period.

But West et al didn’t stop there – they wanted to see what happened over the longer term. In a subsequent study, they took twelve healthy young men and studied the effects of training-induced hormone spikes on arm growth over a 15-week period[3]. Instead of dividing the lads into two groups, the researchers had them train their arms on separate days during the study. One day, their arm workout was followed by leg training. On the other day, they performed the arm workout only.

In weeks 1–6, the subjects trained each arm three times over 2 weeks, allowing 72 hours between the arm+leg and arm-only workouts. This format was used to ensure that enhanced post-workout muscle protein synthesis, which can be elevated in the untrained state for around forty-eight hours, occurred exclusively on the background of basal hormone concentrations after the arm-only workout and was not influenced by the hormonal spike from the arm+leg workout.

The researchers had previously shown that regular weight training shortens the duration (i.e. <28 hours) for which muscle protein synthesis is elevated after exercise, so in weeks 7–15, an extra training session was added to enhance the training stimulus. This meant each arm was now being trained twice per week with at least 48 hours between workouts.

Participants consumed eighteen grams of whey protein immediately before exercise and 18 grams at 90 minutes after all arm workouts to support maximal rates of muscle protein synthesis both in the absence and presence of elevated hormone concentrations. This procedure also helped to reduce variability of and standardize the nutritional environment surrounding the training sessions.

The workouts in the arm-only group consisted of bicep curls performed with one arm only. Three to four sets of 8–12 repetitions at a load around 95% of the subjects’ 10-repetition maximum (RM) were performed, such that voluntary failure occurred during the final set.

The same bicep curl routine was performed by the arm+leg group, but was then immediately followed by five sets of 10 repetitions of leg press and three sets of 12 repetitions of leg extension/leg curl “supersets” (1 set of each exercise, back-to-back, with no rest between sets) at around 90% of 10 RM. Between-set rest intervals for arm and leg exercises were 120 and 60 seconds, respectively. Participants followed a progressive training protocol, increasing the amount of weight lifted as their strength increased. Each training session was supervised individually, and compliance across 56 sessions (28 per arm) was 96%.

There was no elevation in serum growth hormone (GH), insulin-like growth factor (IGF-1), or testosterone after the arm-only protocol but significant elevations in these hormones immediately and 15 and 30 minutes after the leg+arm protocol. This significant difference in hormonal output was seen at both the start and end of the study.

So, once again, heavy leg training and short rest periods produced markedly higher post-workout hormone levels. But did this have any positive effect on muscle growth or strength increases?

Nope.

At the end of the study, there were no significant differences in any of the measured hypertrophy or strength variables. The cross sectional area (CSA) of type I muscle fiber increased 9% and 11%, type II muscle fiber CSA increased 21% and 24%, and elbow flexor CSA increased by 12% and 10% in in the arm-only and arm+leg groups, respectively.

Isometric strength increased by an average 20% and 19% in the arm and arm+leg groups, respectively. Similarly, 1 RM increased 23% and 25%, and 10 RM increased 46% and 47%.

More Research Debunks the GH-Spike Theory

de Souza et al, from the Metropolitan University of Santos in Brazil, compared the effect on strength and hypertrophy of eight weeks’ weight training using constant rest intervals and decreasing rest intervals between sets[4]. Twenty young men recreationally trained in strength training were randomly assigned to 2 groups. During the first two weeks of training, 3 sets of 10-12 repetition maximum with 2-minute rest intervals between sets and exercises were performed by both groups.

During the next six weeks of training, one group continued using 2 minutes rest between sets and exercises (4 sets of 8-10RM),while the other used rest intervals that gradually declined from 2 minutes to 30 seconds as the remaining 6 weeks  progressed (4 sets of 8-10RM).

Total training volume (load × repetitions) of the bench press and squat were significantly lower for the decreasing rest interval group compared to the constant interval group (bench press 9.4% and squat 13.9% lower).

No significant differences were shown between the constant and decreasing rest interval groups for muscle cross sectional area (arm 13.8 vs. 14.5%, thigh 16.6 vs. 16.3%, respectively), 1RM (bench press 28 vs. 37%, squat 34 vs. 34%, respectively), and isokinetic peak torque.

de Salles et al randomly assigned thirty-six recreationally trained men to 1 minute, 3 minutes or 5 minute rest intervals[5]. Each group performed the same resistance training program for sixteen weeks. Four workouts were performed each week with the target rep ranges (4-6 RM and 8-10 RM) alternated every other workout.

The total training volume performed by the 3- and 5-minute groups was significantly greater for the bench press and leg press over the 16-weeks. Despite similar baseline bench press strength, the final results in this lift were 92.5 versus 98.2 kg in the 1- and 5-minute groups, respectively. For the leg press, the final scores were 276.7, 305.and 321.7 kg in the 1-, 3-, and 5-minute groups, respectively. Muscle hypertrophy was not measured in this study.

Robinson et al assigned thirty-three strength trained men into 3 equal groups[6]. All used the same set, rep and exercise scheme except that rest periods varied according to group (30, 90 and 180 seconds). Training was performed four days per week for 5 weeks. At the start and conclusion of the study the following variable were measured:

• 1 RM squat
• vertical jump height
• performance during intermittent stationary bicycle sprint exercise (peak power, average peak power across 15 sprints, average power during each sprint, total work during each sprint and average total work of 15 sprints)
• Body mass and composition

One rep maximum in the squat increased by 3kg, 7 kg and 9 kg in the 30, 60, and 180-second groups, respectively. Vertical jump ability did not improve significantly in any group. No significant difference in cycle sprinting outcomes was observed. No significant differences in body weight, skinfold or girth measurements were seen between the groups.

Western Australia researchers also examined the effect of manipulating rest period length on cycling sprint performance[7]. This study varied from most in that it involved female subjects and used higher rep ranges (15-20 RM) during the 5-week training regimen.

The eighteen active females were matched according to leg strength and repeated-sprint ability and randomly allocated to one of two groups; one group performed weight 3 days a week with 20-second rest intervals between sets, the other  used 80-second rest intervals. Repeated-sprint ability (5 x 6-second maximal cycle sprints) improved to a greater degree after training with 20-second rest intervals (12.5% vs 5.4%) while greater increases in 3 RM squat strength occurred after training with 80-second rest intervals (45.9% versus 19.6%). There were no changes in body composition or weight for either group following training.

Buresh et al compared 60 and 150 second rest periods on changes in hormone response, strength, arm and thigh cross-sectional area and body composition during a 10-week training period[8]. Twelve untrained males trained four times per week and were instructed to consume 1.7 grams of protein per kilogram of body weight during the study.

One potential flaw of this study is that, unlike most other similar studies, the subjects conducted the majority of their workouts unsupervised. In other words, there were no researchers or trainers to ensure that the subjects adhered to the prescribed rest intervals; as anyone who has trained on both short and long rest interval routines, the former often require far greater discipline. Getting back under the bar after a mere minute’s rest, while you are still puffing like a locomotive from your previous set, requires a certain level of internal fortitude. One may reasonably question whether a group of subjects with no previous weight training involvement possessed this requisite level of fortitude. However, training logs maintained by both groups indicated shorter workout duration in the 60-second rest group, as would be expected due to their shorter rest intervals.

In week 1, postexercise plasma testosterone and cortisone levels were greater in the 60-second group, but no differences were seen in GH levels. At weeks 5 and 10, there were no differences in hormone levels. Arm cross sectional area increased significantly more with 150-second than with 60-second rest periods. There were no differences in strength increases.

Training in Tokyo

Japanese researchers measured acute changes in serum GH after 3 types of knee extension routines:

• “hypertrophy-type”
• “strength-type” (S-type),
• “combi-type”

The male subjects aged 20–23 years had a minimum of several months’ weight training experience, but they had not taken part in any regular training program for at least 6 months prior to the beginning of the study[9].

In the hypertrophy-type routine, eight of the subjects performed nine sets of leg extension at 80–40% of 1RM. The session was divided into three parts with 3 sets each, and the rest periods between sets and parts were 30 seconds and 3 minutes, respectively. In each part, the percentage of 1RM was gradually lowered set-by-set.

The strength-type routine consisted of five sets at 90% of 1RM with 3-minute rest periods between sets.

In the combi-type regimen, subjects completed a routine identical to the strength-type protocol, but with an additional set of exercise of 50% of 1RM after the last set, with a 30-second rest period (similar to the final “back-off” set concept that used to be popular with bodybuilders back in the 80s).

GH concentrations were significantly higher after the hypertrophy-type regimen (419.8 ng·ml-1) than after combi-type (221.5 ng·ml-1) and strength-type (56.1 ng·ml-1) regimens.

To ascertain whether this made any difference to long-term weight training outcomes, the researchers then got sixteen subjects to perform leg press and leg extension exercises twice per week. During the first 6 weeks, all subjects used the hypertrophy-type regimen to gain muscular size (in this phase, the hypertrophy protocol consisted of two parts of 3 sets). During a subsequent four week strength phase, they were divided into two groups performing combi-type and strength-type regimens.

No significant changes were observed in body mass or percentage of body fat at any time points over the training period. Cross sectional thigh muscle area significantly increased in both groups during the hypertrophy phase. During the subsequent strength phase, CSA showed a further increase in the combination group but not the strength group but the difference was not statistically significant.

Muscular endurance assessed by work volume performed in the knee extension exercises improved significantly in both groups during the hypertrophy phase but showed a further increase during the strength phase only in the combination group (18.8 vs 24.7%).

1RM increased similarly during the first six weeks in both groups, but rose by significantly higher during the subsequent strength phase in the combination group (14.7%) than in the strength group (9.3%).

So in the final four weeks, a routine associated with higher GH output did result in statistically significant greater gains in 1RM and muscular endurance. Given the evidence so far, it’s probably safe to assume that these improvements had little to do with GH release but rather the neuromuscular and metabolic effects of the extra high-rep set. The light weight used in this set would have allowed a more explosive lifting action, possibly assisting in power and force development during performance of heavy lifts (explosive lifting with light weights is now  a mainstay of many powerlifting routines). Meanwhile, the high repetition range of the extra set would have allowed for greater improvements in muscular endurance than the routine comprised only of low rep sets.

Another ‘Bro-Science’ Myth Busted

While certain training strategies can spike post workout release of GH (and testosterone and IGF-1), there is no evidence to show that these spikes in any way enhance muscle growth or strength gains.

Many weight trainers, having become especially enamored with the hormone-spiking theory, will have a hard time accepting this finding. However, when one considers the broader research findings, it makes perfect sense. Daily injections of recombinant growth hormone fail to add lean muscle to young men[10], so it’s hardly surprising that short-lived post-workout spikes in GH fail to do the same. Testosterone injections do indeed pack plenty of muscle onto a young buck’s frame, but only after raising blood levels of the mighty T to far higher levels than would ever be seen as a result of training-induced manipulations[11]. Interestingly, it’s well-known among the juicing fraternity that while GH injections often amplify the muscle-building effects of exogenous testosterone and anabolic steroids, used alone they have little effect on muscle hypertrophy.

While a minimum level of natural testosterone production is necessary for growth, and suppression of this production impairs the response to strength training[12], any short-lived spike achieved after training does not appear to exert a meaningful impact over and above that exerted by endogenous testosterone levels.

The mechanisms behind increases in exercise-induced hormones are unclear but, as West et al point out, are more likely related to metabolic stress and/or fuel mobilization rather than muscle anabolism. For example, strenuous regimens involving reduced rest times impede intra-workout recovery and result in greater lactate accumulation, which in turn appears to trigger greater GH output.

What Does This Mean For You?

Should you stop doing squats and discard short rest periods to the scrap heap of training history?

Hell no.

Irrespective of their effects on GH, squats are one of the most highly productive exercises a strength athlete could possibly perform. Not only do they provide a high degree of stimulation to the thigh, gluteus and lower back musculature, but they force a myriad of other muscles to assist in stabilizing the torso and fixing the loaded barbell in place on the lifter’s back or clavicles (in the case of front squats). Furthermore, the hip control learned during squatting is invaluable when instructing trainees in proper performance of many other lifts, especially the Olympic lifts and their variants. These training effects simply cannot be mimicked by using squat alternatives such as the leg press or machine hack squat.

As for short rest periods, I have witnessed some rather spectacular hypertrophy and strength gains in trainees performing routines with rest periods as low as 30 seconds. If this seems counter-intuitive in light of the evidence just presented, let me emphasize some important points:

• With the exception of the Japanese study which used an extra high-rep set, the studies discussed above invariably prescribed the same number of sets and reps. In the long rest groups, where greater recovery between sets occurred, this allowed a higher weight to be used during subsequent sets, because the load on the bar often had to be reduced to maintain the desired rep range in the short-rest groups. This means that total volume (in terms of total greater poundage), a critical factor in strength and hypertrophy outcomes, was significantly greater during the longer rest routines. However, perhaps the greatest value of using short rest periods is that they will allow more sets, and hence greater total volume, to be performed during a given time frame. If your weight training sessions last 40-60 minutes, you’ll fit many more sets in when using short rest periods.
• The impressive gains I have witnessed during short rest protocols were made in the context of programs that interspersed lower- and higher-volume phases, a highly effective technique for eliciting hypertrophy and strength gains and routinely used by elite weightlifting teams. The short-rest periods were used during the high volume phases for the reason just discussed above.

Also, I’ve observed that as a trainee adapts to using short rest periods, there is often little to no drop in weight on many exercises when working in the 5-6 rep range, while drops in weight are still necessary when using > 8 reps, no doubt due to the different primary energy pathways employed by these divergent rep ranges.

So keep squatting, and strongly consider interspersing training phases employing short rest periods with those using longer rest periods. Also be aware that there’s a way to minimize the reduction in weight that occurs during short-rest routines: performing exercises for different bodyparts back-to-back. This allows you to maintain a high volume of work during your training sessions (and a high calorie burn, which is especially helpful when trying to create a calorie deficit for fat loss).

Few studies have looked at this strategy; a recent study by researchers from the University of Ballarat in Victoria, Australia compared the acute effects of performing paired set versus traditional set training over 3 consecutive sets on volume load and electromyographic (EMG) activity of the pectoralis major, anterior deltoid, latissimus dorsi, and trapezius muscles[12]. There was no difference between volume load or EMG activity of the four monitored muscles was not different for the 2 conditions. However, the average rest between sets was 4 minutes in the traditional sets group, and 2 minutes in the paired set group, which is far longer than what I’ve successfully employed with myself and others (typically 10 – 30 seconds).

The paired set approach is a viable way to increase workout efficiency by greatly increasing volume without increasing the duration of your workouts. Caution should be exercised when using the paired set (or “superset”) approach with little or no rest – exercises requiring a high level of concentration and co-ordination, such as the Olympic lifts, are best performed in the traditional straight set manner, with sufficient rest periods to allow the performance of subsequent sets with minimal fatigue in order to maintain optimal technique. High demand exercises like squats and deadlifts are also probably best performed in straight set fashion.

Conclusion

Don’t waste your time chasing GH spikes during and after your workouts. The evidence overwhelmingly indicates that workout-induced hormone spikes have no effect on muscle growth and strength gains. Focus instead on optimizing far more important training variables such as volume, frequency and exercise selection.

Stay tuned for part 2, where we’ll destroy another laughable low-carb myth, that of wonderfully high GH output as a result of carbohydrate restriction.

—

Anthony Colpo is an independent researcher, physical conditioning specialist, and author of the groundbreaking books The Fat Loss Bible and The Great Cholesterol Con. For more information, visit TheFatLossBible.net or TheGreatCholesterolCon.com

References

Hansen S, et al. The effect of short-term strength training on human skeletal muscle: the importance of physiologically elevated hormone levels. Scandinavian Journal of Medicine & Science in Sports, 2001; 11: 347–354.

West DW, et al. Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men. Journal of Physiology, 2009; 587: 5239–5247.
http://jp.physoc.org/content/587/21/5239.full.pdf+html

West DW, et al. Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors. Journal of Applied Physiology, 2010 Jan; 108 (1): 60-67.
http://jap.physiology.org/cgi/content/full/108/1/60

de Souza TP Jr, et al. Comparison between constant and decreasing rest intervals: influence on maximal strength and hypertrophy. Journal of Strength & Conditioning Research, Jul, 2010; 24 (7): 1843-1850.

de Salles BF, et al. Strength increases in upper and lower body are larger with longer inter-set rest intervals in trained men. Journal of Science and Medicine in Sport, 2010 Jul; 13 (4): 429-433.

Robinson JM, et al. Effects of different weight training exercise-rest intervals on strength, power and high intensity exercise. Journal of Strength & Conditioning Research,1995; 9: 216-221.

Hill-Haas S, et al. Effects of rest interval during high-repetition resistance training on strength, aerobic fitness, and repeated-sprint ability. J Sports Sci. 2007 Apr; 25 (6): 619-28.

Buresh R, et al. The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training. Journal of Strength & Conditioning Research, 2009 Jan; 23 (1):62-71.

Goto K, et al. Muscular adaptations to combinations of high and low intensity resistance exercises.Journal of Strength & Conditioning Research, 2004; 18: 730-737.

Yarasheski KE, et al. Effect of growth hormone and resistance exercise on muscle growth in young men. Am J Physiol Endocrinol Metab, 1992; 262: E261–E267.
http://ajpendo.physiology.org/cgi/reprint/262/3/E261?ijkey=52412d739c04b9f120ffe4bce648bcc0b184935c

Bhasin S, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. N Engl J Med, 1996; 335: 1–7.
http://content.nejm.org/cgi/reprint/335/1/1.pdf?ijkey=58de964f45a998acc7eb83f9d6f777a8efd54922

Kvorning T, et al. Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study. Am J Physiol Endocrinol Metab, 2006; 291: E1325–E1332.
http://ajpendo.physiology.org/cgi/reprint/291/6/E1325?ijkey=f4686a7d641507dc9e11c406c533a8fff0eb92ab

Robbins DW, et al. Physical performance and electromyographic responses to an acute bout of paired set strength training versus traditional strength training. Journal of Strength & Conditioning Research, 2010 May; 24 (5): 1237-1245.

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