Three is More Than One: Higher Volume Increases Strength Gains in Legs, and Satellite Cell Recruitment and Fiber Size in Legs & Traps. Plus: Data on Myostatin, IGF1, MGF & Co.

Image 1: The green dots that are crowding left and right from the blue myonucleus are the satellite cells (Hanssen. 2012)

In case you are not really sure what a "satellite cell" is and why you should care abouts it's "recruitment", you have probably missed the Intermittent Thoughts on Building Muscle series and should get into detention. Otherwise, here is the news: In a study that has been published in the latest issue of the Scandinavian Journal of Medicine in Sports Science T.S. Hanssen et al. published a paper with the auspicious title "The effect of strength training volume on satellite cells, myogenic regulatory factors, and growth factors" (Hanssen. 2012). Exactly that kind of study that would have the potential to take the mostly common or bro-sensical reasoning behind the current recommendations on training volume to the next, a scientific level, if it the scientists would finally realize that strength training noobs are hardly a better model for advanced trainees than rodents :o(

Full body training 3x /week: How many sets are optimal?

For their study, Hanssen et al. recruited twenty two healthy untrained men (age 26.5y; height: 181.8cm; weight: 81kg) and assigned them to one out of two full-body workouts, with identical exercises (leg press, leg extension, leg curl, seated chest press, seated rowing, latissimus pull-down, biceps curl, and shoulder press), but different amounts of sets for a given body part:

• 3x Legs & 1x Upper Body: Trainees in this group performed 3 sets for each of the leg exercises and 1 set for the upper body exercises
   
• 1x Legs & 3x Upper Body: Trainees in this group performed 1 set for each of the leg exercises and 3 sets for each of the upper body exercises

All subjects started out with 10 reps per set in the first two week. In weeks 3-6, the intensity was increased to 8RM and in the last 5 weeks (7-11) all participants trained at their "7-rep max":

Participants were encouraged to continuously increase their RM loads during the intervention and they were allowed assistance on the last repetition.

In addition to the three strength training sessions per week, the participants were allowed to perform one (not more!) additional steady-state cardio session. And while this may help with standardization, my mathematical skills tell me that the 3L-1UB group performed only 14 sets per workout, while the 1L-3UB group performed 18 sets, simply because the number of lower and upper body exercises was not identical. Now, everyone who does not claim that he or she does not need to train legs (for whatever stupid reason) will know leg training is much more draining than upper body workouts, so "intensity-wise" the workouts were probably still identical.

Single vs. multiple-set training? Nothing new or exciting if it was not for the specific data

We have seen similar studies before - most of them with the same, very unfortunate limitation of being performed on strength training novices, by the way - and the results of this study would hardly be exciting, if it were not for the sheer amount of data Hansson et al. recorded:

Image 2: If those acronyms don't ring a bell, click here to learn more.

• muscle strength and muscle fiber size,
  
  
• the number of satellite cells and number of satellite cells positive for myogenin and MyoD,
   
• the number of myonuclei, myogenin and MyoD content of muscle samples, and
  
  
• myostatin and a whole host of growth factors, namely IGF-1, MGF, HGF, FGF2 and VEGF

This is what I call a "comprehensive" analysis ;-) And one which brought about some pretty interesting results, of which the increases in muscle strength and fiber size are unquestionably the most straight-forward and least surprising ones (cf. figure 1):

Figure 1: Changes in 1RM strength and fiber area after 11 weeks on the training regimen with different set schemes (data calculated based on Hanssen. 2012)

As you can see in figure 1 strength-wise, only the leg (m. vastus lateralis), yet not the back (trapezius) muscle benefited from the increased training volume. When you do take a look at the fiber size, however, it becomes obvious that as long as we compare 1 vs. 3 sets more is actually more +24%, to be precise (the 4% difference for the fiber size in the legs is statistically non-significant).

Figure 2: Relative changes in myonuclei number per muscle fiber and the number of satellite cells after 2 and 11 (post) weeks of the training intervention (data calculated based on Hanssen. 2012)

If you also take into account that the data in figure 2 clearly shows that an increase in training volume leads to increased satellite cell recruitment (indicated by the increases in the number of myonuclei per muscle fiber) and number, it becomes obvious that you are missing out on the growth promoting effects of strength training. The decrease in myonuclei per muscle fiber in the latter 9 weeks of the training intervention in the low volume upper body group (dark red bars in figure 2) would also suggest that this is particularly true for the experience strength trainee in whom the initial 2-week growth spurt of which Hansson et al. state that it was one of their two "main observations":

The novel finding in our study was the early increase in the proportion of activated satellite cells, the early increase in total number of satellite cells and the dependence on training volume in the leg muscle. The number of activated satellite cells, indicated by myoD and myogenin expression, increased from ~2% before training to 6–10% 2 weeks into the intervention.

So as "novel" as this finding may be, it is still somewhat unsatisfying for experienced strength trainees, who will have to rely on the hypothesis that their response will be an ameliorated version of the "late" growth response in the study at hand, which would support my personal observation that 3x3 i.e. three exercises à three sets per body part is at the lower end of the "optimal" volume continuum for advanced trainees. A volume continuum, by the way, that is capped at 12-15 sets for the largest body parst, i.e. legs and back and does by no means extent into the "insanity realm", where people perform 20 sets for biceps and 20 working  sets for triceps on a 5-day body-part split.

Surprise: No statistical significant differences in growth factors

What I found quite surprising though, is that this advantage of 3- vs. 1-set training was not reflected by greater increases in myostatin and/or MGF (want to know more about MGF, click here for the pertinent installment of the Intermittent Thoughts). MGF was even higher in the vastus of the 1 set group and the smaller incline in myostatin levels in the 3-set group (1.1x vs. 1.8x) did not reach statistical significance.

Figure 3: Changes in mRNA levels of myostatin, IGF-1, MGF, HGF, FGF2, and VEGF in the 10 subjects with the largest satellite cell response (seven from 3L-1UB and three from 1L-3UB; data adapted from Hanssen. 2012)

If we do yet take a look at the changes in mRNA levels of myostatin, IGF-1, MGF, HGF (hepatocyte growth factor; growth factor for satellite cells, cf. Sheehan. 2000), FGF2 (fibroblast growth factor; promotes cell adhesion and proliferation, as well as the build up of callege, cf. Yun. 2012) and VEGF (cf. figure 3) in the 10 subjects with the largest satellite cell response (seven from 3L-1UB and three from 1L-3UB), we do see that all but myostatin and VEGF were statistically significantly elevated above baseline. These results stand in line with the main message of the Intermittent Thoughts which was that it is the interaction of a whole host of "hormones" (and peptides) that "builds muscle" - and not as the producers of a certain category of 100% useless "all-natural" supplements want to make you believe, testosterone (or any other growth factor) alone.

And while it was to be expected that the expression of those growth factors would decline over the course of the 11-week intervention period, I am honestly wondering, whether the decrease in reps from 10 (initial two weeks) to 8 and subsequently 7 reps per set had anything to do with it... but I guess, this is an issue for the next study, about which, you will read nowhere else than right here, at the SuppVersity, the place where bro- and pro-science unite in the spirit of true wisdom - but I guess you know that by now, don't you? ;-)