Monday, January 14, 2013

Exercise Research Quickie: HIIT vs. Steady State, More on the Hormonal Response. Light Training, High TUTs & Peak Contractions - Not Just for The Elderly. Train Your Left, Grow Your Right Leg - Contralateral Training Effects

The role of the innervations between our muscles as well as to our brain is often overlooked, when we are talking about size gains. The image shows stained nerve fascicles from the Song study, which brings this wiring back onto the radar.
I know that we have had the short news on Saturday only and that there are of course tons of short news on Facebook everyday, but the studies I am going to present you in this exercise research quickie were so in-between (meaning not really worth a full post, but still way too good to be wasted on facebook) that I decided to devote a post of its own to the research on the hormonal effects of interval vs. steady state training by Hackney et al. (Hackney. 2012b), the impressive and certainly not totally irrelevant effects of slow movement, low-intensity resistance training in the elderly Watanabe et al. describe in their latest paper and the surprising muscle building (Watanabe. 2013) and growth priming carry over effects Song et al. observed in response to unilateral electrical muscle stimulation (Song. 2012).

Although, the latter post is pretty theoretical I hope that all of you will find something that enlightens, amuses or entertains them in this "threesome" ;-)

More T, more DHT, more cortisol - that's the HIIT vs. LISS formula

(Hackney. 2012b) -- In fact the results of two subsequently published papers by Hackney et al. would suggest that it's about as easy. Work out hard and fast and see greater increases in testosterone levels, but also testosterone turnover (into DHT via 5-alpha reductase), but don't forget that aside from these (questionable) anabolic benefits, your thyroid hormone levels are going to take a dive (as reported previously), as well.

Figure 1: Comparison of the hormonal responses measured in the plyometrics (left) and the HIIT vs. LISS (right) study (based on Ozen. 2012 and Hackney. 2012)
The figure above is actually from a post where I discussed this before, so if you cannot remember all the details, briefly go back before you take a look at the summary of results of the more recent study by Hackney.

"Dihydrotestosterone (DHT) - Bigger, Stronger, Faster or just Balder, Fatter and Unhealthier?" That's the question I asked in one of the installments of the Intermittent thoughts on building muscle. A post I would highly suggest you read, by the way ;-)
In this 2nd paper that was published right before Christmas in the Journal of Endocrinological Investigations the researchers were able to show that repeated periods of 90-sec treadmill running at 100-110% maximal oxygen uptake (VO2max) and 90-sec active recovery at 40% VO2max for 42-47 min (which is obviously pretty long!) caused  just a significantly more pronounced increase not just in free testosterone, but also in its conversion to testosterone's big brother DHT (as indicated by statistically higher levels of the 5α-reductase marker 3-α Diol G at 12POST HIIT vs. LISS). This is interesting, as dihydrotestosterone (DHT) which is often falsely associated only with hair loss, prostate cancer and even obesity, does also play an important role in strength development (click here to learn more) and appears to do it's magic via the MAPK receptor. Now, MAPK in turn can activate PGC-alpha and that the latter is way more than just the endurance / mitochondria builder it was long thought to be is something you should still remember from the post on the"The IGF-1 Promoting, Myostatin Reducing, Muscle Building Effects of PGC-1 α-4" (read more).

Bottom line: It is becoming more and more clear that HIIT is in fact somewhat of a chimera that shares beneficial and detrimental effects of both classic cardio and classic strength training with mammoth sessions like the one performed in the studies at hand triggering similar hormonal cascades that will - despite probably causing beneficial adaptations - simply require longer rest times than a classic LISS regimen.
A  note of caution: Both these studies point to the highly questionable "value" of taking a bunch of people letting them do whatever type of training once, measure some stuff of which you do only have a very rough idea of what it's actually doing and then have a bunch of morons like myself try to come up with "practical implications"
So if you do HIIT, stick to the principles "short and hard" (I would never suggest doing the >40min interval sessions for anyone whose primary goal is to be healthy and look good naked, by the way; add a walk on the treadmill if you want to train longer like on a combined HIIT + LISS cardio only day. But most importantly don't forget to enjoy your well-deserved, highly productive off-time and remember that it's during those hours, when all the hard work is paying off... ah I almost forgot, this is a tried and proven way that happens to be confirmed by studies like Hackney's and not vice versa.

 Light training, high TUTs and peak contractions - not just for the elderly?!

You cannot only implement"light" training into your established routine (see last paragraph), but should also think of the often forgotten benefits of periodization, detraining & co (learn more), as well as times, when you may be injured or otherwise disabled and cannot lift heavy.
(Watanabe. 2013) -- It may sound like a study for the elderly, but just as the best-agers among the SuppVersity readers can learn something from studies done in the the younger fellows, the younger weightlifters may well get some intriguing insights from studies with older participants - studies like the one by Watanabe et al., for example.

When the researchers from the Department of Life Sciences at the University of Tokyo compared the hypertrophy and strength gains of two exercise regimen using a low resistance of 50% of the personal 1-RM max of their 59-76yr old subjects, the scientists found that slow movements with tonic force generation were superior to the regular 1s concentric vs. 1s eccentric reps I guess most of you will be employing in their training routines.

The subjects who had been randomized to the LST group and performed their reps with a 3s concentric, a 3s eccentric and phase and most importantly a peak contraction in-between did gain a similar amounts of strength as those subjects who performed the standard protocol for 10 weeks (the 12-week study had a 2-week familiarization phase), but contrary to they did also record statistically significant increases in muscle size.

Alternative exercises on which peak contractions work well, are the fly (preferably on a machine or using cables), the lat pulldown, cable crunches, all sorts of triceps extensions, the scott curl (where you would do them midrange), every form of calf raises. Always remember, though: A peak contraction is never done in the full stretch position, but always either midrange or as the name implies at the peak of the contraction, before the eccentric phase begins.
So what does that mean? Certainly not that all of you should stop lifting heavy weights, because 50% 1-RM was enough if not superior to the regular 70-90% that are recommended in most serious training regimen. Rather, these results should remind young and old trainees alike of keeping an eye on your form and making sure that you stimulate the muscle and don't just move whatever weight from place A to place B.

That said, try to incorporate peak contractions with every rep on the auxilliary movements of your next workout. Start your leg workout with regular squats, for example, 5x5 TUT 101 (meaning 1s eccentric, 0s rest at the bottom, 1s concentric), but instead of the 4x10 leg extensions you would usually do for your quads, you lower the weight somewhat and do them with a slower rep-speed (somewhere in between 1-3s) and a peak contraction (meaning you really squeeze the muscle in a position, where your knees are almost locked out). Done right, this is going to give the word DOMS (=deep onset muscle soreness) a whole new meaning + you will have to reduce your weights, anyways.

Train your left leg and your right one will grow as well

(Song. 2012) -- Do our bodies know something about aesthetics? Well, if that were the case, the legs of some of the gymbros who "don't train legs, because [they] play soccer" shouldn't look the way they do... but I am digressing here. According to the study by Yafeng Song et al. have just published in the open access journal Plos ONE, there appears to be a certain carry-over effect - at least if the growth stimulus is chronic and profound.

To achieve the latter, i.e. a chronic and profound training stimulus, the researchers from the Umea University in Sweden exposed the soleus and gatrocnemius muscles of rabbits to a 6-week electrical muscle stimulation + exercise protocol and measured muscle changes and inflammation on weeks 1, 3 and 6 of the study. Now, the clue of the study was that the unilateral "exercise" was actually mechanically and electrically enforced, so to say:
"The movements are produced by a pneumatic piston, in which the range of motion can be controlled. The range of movement was set to 9.5 cm, given a range of motion in the ankle of 55–65u of which 20–25u was dorsiflexion and 35–40u was plantarflexion. The right leg was attached to the piston and the pelvis/hip region was strapped down to restrict the motion in the left non-exercised leg. The left leg was unattached. During the plantar flexion of the right leg, an active contraction was induced by electrical muscle stimulation via surface electrodes placed 2 cm apart over the right triceps surae muscle. The stimulation was synchronized with the plantar flexion movement of the piston by a microswitch, which trigged the stimulator unit".
I will spare you the further details... just think of a modern rabbit torture machine that was designed to "work the rabbits right extremities out". As you would expect from any good torture machine this device brought about a significant amount of tissue damage and a corresponding increase in the number of necrotic fibers.
Figure 2: Variability in fiber size, fibers with internal nuclei, inflammation in soleus (left) and gastrocnemius muscle (right) in response to the exercise + electrostimulation program. Mind the similar responses in the exercised (E) and the non-exercised (NE) limb (Song. 2012)
Now what's surprising though is the fact that despite the local damage, the inflammation had a systemic component, which happened to be more pronounced in the untrained soleus vs. gastrocnemius muscle (slow vs. fast twitch, by the way).

Against that background it is still only a little less surprising that the variability in fiber size, the number of fibers with internal nuclei (=sign of restructuring process, cf. "The Skeletal Muscle Hypertrophy 101") and even the fiber splitting were virtually identical. After all, this would mean that systemic parameters do matter. But haven't we just discarded this notion yet another time in the first of the items in today's exercise research quickie? Yes we have, but in that case we were talking about the usual subjects, the "anabolic" and "catabolic" hormones, Song et al. on the other hand speculate that
"[t]he collateral muscle changes and inflammation after unilateral EMS/E observed in this study may be caused by [a] neuronal mechanism. Since there is some evidence for a commissural system in the spinal cord that mediates transmedian signaling with a fairly precise bilateral representation, nerve signals from the trained side may pass over to the contralateral muscles through commisural inter-neurons. If this is the case, unilateral injury caused by EMS/E may cause a cross-transfer up-regulation of neuropeptides that can be involved in the inflammatory response in the contralateral muscles." (Song. 2012)
The researchers indicate that their current, as well as previous results from their laboratory would support this hypothesis and that any systemic or circulatory effects must actually be excluded, because these would not have occurred only focally, but generally within all muscles. They also point towards previous studies in which the signalling between contralateral and ipsilateral limb was blocked and the observed cotralateral responses were abolished.

So what's the point? I will openly admit that the practical relevance of these results (esp. for you as a hopefully healthy trainee) is as of now still very questionable, but the fact alone that it brings the nervous system back on the "scientific" radar was certainly worth including it in this "threesome" - don't you think so? No, well... maybe you like the scientists own rational who argue that the findings are (a) important in the context of a wide range of musculoskeletal and neuromuscular disorders and (b) relevant for each and every unilateral exercise experiment, where the contraleteral limb is used as a control - and you know there are plenty of them!

References:
  • Hackney AC, Kallman A, Hosick KP, Rubin DA, Battaglini CL. Thyroid hormonal responses to intensive interval versus steady-state endurance exercise sessions. Hormones (Athens). 2012a Jan-Mar;11(1):54-60.
  • Hackney AC, Hosick KP, Myer A, Rubin DA, Battaglini CL. Testosterone responses to intensive interval versus steady-state endurance exercise. J Endocrinol Invest. 2012b Dec;35(11):947-50.
  • Ozen, SV. Reproductive hormones and cortisol responses to plyometric training in males. Biol Sport.2012; 29 (3).
  • Song Y, Forsgren S, Yu J, Lorentzon R, Stål PS. Effects on contralateral muscles after unilateral electrical muscle stimulation and exercise. PLoS One. 2012;7(12):e52230.
  • Watanabe Y, Tanimoto M, Ohgane A, Sanada K, Miyachi M, Ishii N. Increased muscle size and strength from slow-movement, low-intensity resistance exercise and tonic force generation. J Aging Phys Act. 2013 Jan;21(1):71-84.