Tuesday, November 3, 2015

Muscle Regeneration & Hypertrophy Update: Vitamin D and Super-Slow Training - What Are They Good For?

Is it worth to replete vitamin D, but not to train super-slow, right?
No, I haven't dug up a study that deals with vitamin D and super-slow training at once, but I've found two very recent studies that are in one way or another related to muscle regeneration and hypertrophy and the way/s vitamin D and different training methods affect these outcomes. More specifically, the researchers investigated the effects of vitamin D (20OHD) repletion and the use of higher times-under-tension (TUT) and super-slow training.

Before I go ahead, though, I would like to point out that the long-term implications of some of the results are not totally obvious - a fact I will therefore (re-)address in the bottom line.
If you periodize appropriately you may actually be able to benefit from super-slow training.

30% More on the Big Three: Squat, DL, BP!

Block Periodization Done Right

Linear vs. Undulating Periodizationt

12% Body Fat in 12 Weeks W/ Periodizatoin

Detraining + Periodization - How to?

Tapering 101 - Learn How It's Done!
  • (Super-)slow training and its inferior effects on early-phase satellite cell and myonuclear domain adaptation (Herman-Montemayor. 2015) -- The purpose of one of the latest studies from the Rocky Vista University was to identify adaptations in satellite cell (SC) content and myonuclear domain (MND) after 6-week slow-speed vs. “normal-speed” resistance training programs.

    To this ends, thirty-four untrained women were divided into slow speed (SS), traditional strength (TS), traditional muscular endurance (TE), and nontraining control (C) groups. The ladies performed a leg work consisting of three sets of each of the following exercises twice per week in the first and thrice per week in the fifth week: Leg press, squat, and knee extensions. To investigate how the way these workouts were performed would affect the adaptive response, the scientists randomly assigned their subjects to four different groups:
    • The Super-Slow (SS) group performed 6– 10 repetition maximum (6–10RM) for each set with 10-second concentric (con) and 4-second eccentric (ecc) contractions for each repetition.
    • The Traditional Strength (TS) group and the Traditional Muscular Endurance (TE) group who performed 6–10RM and 20–30RM, respectively, at “normal” speed (1–2 seconds per con and ecc contractions).
    • The sedentary control group (C) which did not work out at all.
    To allow for a similar number of reps in the TS and SS group, the intensity (=weight used) in the SS group was reduced to the same 40–60% of the 1RM that was also used in the TE group. The TS group, on the other hand trained at 80–85% 1RM.
What do the changes in fiber type satellite cell increases actually tell us? Unfortunately, the answer to this question is by no means straight forward. In conjunction with the overall increase in domain sizes, cross sectional fiber size and myonuclear domain numbers (see Figure 1) the increased satellite cell recruitement in the traditional training group does yet support its superiority over super-slow training (learn more about satellite cells).
  • I know that this is not ideal, but there's no way you do 6-10 reps with a time-under-tension (TUT) of 10-0-4 with the same weight you'd do 6-10 reps at a normal TUT of 1-0-1 or 2-0-2, accordingly, the results the scientists' analysis of the pretraining and posttraining muscle biopsies the authors analyzed for fiber cross-sectional area, fiber type, SC content, myonuclear number, and MND still have practical relevance.
    Figure 1: Percentage change (%) in mean fiber cross-sectional area, myonuclear domain size (domain), and number of myonuclei per fiber cross-section (myonuclear number) from pretraining to posttraining for each group (TS, SS, TE, and C). *Significant increase after training, p , 0.001. §Significant increase after training, p # 0.05. #Significantly greater increase after training compared with all other groups (SS, TE, C), p , 0.01. TS = traditional strength (Herman-Montemayor. 2015).
    And what does the scientists' analysis tell us? Well, along with the data in Figure 1, the exclusive increase in satellite cell content of type I, IIA, fibers (IIX and IIAX increased in both SS and TS, but not TE or control) that was observed in the traditional strength (TS) training group appears to confirm the superiority of this way of training when it comes to lying the foundations of further myonuclear domain growth (learn more in the "Muscle Hypertrophy 101").

    The fact that myonuclear domain increases of type I, IIAX, and IIX fibers occurred exclusively in the TS, yet not in the SS group, where only the domains of the type IIA fibers increased, does still appear to confirm the common prejudice that - for the average trainee - training at higher times under tension (TUTs) does not offer benefits that suggest faster or more robust size gains. Compared to strength-endurance training, however, super-slow training is still the better option. On a "per load basis" it is thus more effective to do fewer reps slower vs. more reps at a normal speed if your goal is to "grow" muscle.
  • Vitamin D affects muscle recovery directly (Owen. 2015) -- We already know that vitamin D figures in one way or another in (a) the adaptive response to exercise and (b) the recovery process after strenuous workouts. Unfortunately our "knowledge" is based mostly on correlations and associations and can thus hardly be considered reliable evidence. That's something researchers from the Liverpool John Moores University, the Charité in Berlin, the Norwich Medical School and other European labs weren't happy with, either. Accordingly, they designed a randomised, placebo-controlled trial that involved twenty males with low serum 25[OH]D (45 ± 25 nmol.L-1) who performed 20×10 damaging eccentric contractions of the knee extensors with peak torque measured over the following 7 days of recovery prior to and following 6-weeks of supplemental Vitamin D3 (4,000 IU.day-1) or placebo (50 mg cellulose).

    To complement the results of this human trial, the authors conducted a parallel experimentation using isolated human skeletal muscle derived myoblast cells from biopsies of 14 males with insufficient serum 25[OH]D (37 ± 11 nmol.L-1) that were subjected to mechanical wound injury. Thus, the scientists tried to emulate the process of muscle repair, regeneration and hypertrophy in the presence and absence of 10 nmol or 100 nmol 1α,25[OH]2D3 in the petri dish.
    Figure 2: In view of the fact that the scientists used active vitamin D3 (calcitriol) in the in-vitro study, the improved recovery in the human trial is all the more the more relevant results of the study. It does yet pose the question whether similar or any effects had been observed in subjects with sufficient vitamin D levels in whom the provision of extra vitamin D3 may have increased 25OHD, but not the systemic calcitriol levels of which the scientists' in-vitro dta shows that it is responsible for the effects (Owens. 2015).
    What the results of both studies have in common is that they support the previously claimed role of vitamin D in muscle repair and regeneration. How's that? Well, the supplemental Vitamin D3 the D-ficient human subjects received didn't just increase the serum 25[OH]D levels. It also lead to measurable improvements of the recovery of peak torque at 48 hours and 7 days post-exercise. In conjunction with the observation that 10 nmol 1α,25[OH]2D3 aka calcitriol (=active vitamin D3, not the supplement you consume) improved muscle cell migration dynamics and resulted in improved myotube fusion/differentiation at the biochemical, morphological and molecular level in the cell study, where it also increased the myotube hypertrophy at 7 and 10 days post-damage, these preliminary data do just as the scientists say "characterise a role for Vitamin D in human skeletal muscle regeneration and suggest that maintaining serum 25[OH]D may be beneficial for enhancing reparative processes and potentially for facilitating subsequent hypertrophy" (Owens. 2015).
"Explosive Reps May Pay Off - At Least on the Bench: Fast Reps = Higher Muscle Activity, Higher Volume... Gains?" Find the answer to this question from a previous SuppVersity article here.
So what? Yes and no! Those are the answers to the questions you are probably about to ask. Yes, it does make sense to keep an eye on your vitamin D (25OHD in serum) levels, to do blood tests regularly and to supplement according to your personal needs. Yes, it does also make sense to get 1,000 IU of vitamin D3 per day even if you don't know you're deficient. And yes, all that may actually help you to recover faster.

What neither vitamin D3 nor super-slow training will do, though, is to turn you into a ripped super-muscular freak. In fact, the answer to the rarely asked question whether it makes sense to switch from a regular hypertrophy training regimen with a TUT of 1-0-1 or 2-0-2 to a super-slow regiment, is "no". Or more precisely: No, it is not generally recommendable to do super-slow training instead of regular resistance training if your goal is max. muscle hypertrophy.

A question the study by Herman-Montemayor cannot answer, however, is whether doing super-slow training only least temporarily (as part of a perdiodization scheme, for example) would help pro-athletes to make further or faster progress. Even without a study, though, it can be said that someone who has been training with a TUT of 1-0-1 and weights corresponding to his/her 6-10RM (=80-85% of 1RM) for years and for whom the super-slow training would constitute a novel training stimulus is probably more likely to benefit from intermediate super-slow training than the subjects in the study at hand for whom this was the first 6-week gym experience | Comment on Facebook!
References:
  • Herman-Montemayor, Jennifer R., et al. "Early-phase satellite cell and myonuclear domain adaptations to slow-speed versus traditional resistance training programs." Journal of strength and conditioning research/National Strength & Conditioning Association (2015).
  • Owens, Daniel J., et al. "A Systems Based Investigation into Vitamin D and Skeletal Muscle Repair, Regeneration and Hypertrophy." American Journal of Physiology-Endocrinology and Metabolism (2015): ajpendo-00375.