Classic Beats Super Slow; Single 198 Second Sprint More Time Efficient Than Work-Matched HIIT; Exercise Better Than THC; Metformin + Cardio + Lifting = Anti-Obesity Triplet; Self-Efficiacy & Training Adherence - Plus: More!

This is just a random selection of the unlimited movement patterns your body has been designed to execute - don't make the mistake and rely on only one of them!

The amount of really interesting, let alone revolutionary new studies on the effects of different exercise modalities is not exactly high, to say the least. I am not quite sure, what the reasons are, but as I have stated before, part of it certainly is that you cannot monetize on the results by producing patentable drugs based on your findings and will thus have a hard time to find sponsors / get funding. It is therefore no wonder that many published papers are spin-offs of small scale trials that have been conducted as part of dissertations. Others simply use rodent models, which may provide relatively reliable data, when it comes to the effects of running on a treadmill, but are not exactly what I would want to see, when it comes to weight lifting or any other of the myriad complex movement patterns our bodies can, but these days way too often don't do.

I have nevertheless been able to compile another potpourri of studies of which I would hope that one or the other will enlighten or at least entertain you. That being said, let's get started with this weeks installment of the Exercise Science Special of "On Short Notice", here at the SuppVersity...

---

HIT it short, hit it hard, hit the glucose and be smart! Yo, this awesome rhyme would be my advice to the very busy chubby manager-types with compromised insulin sensitivity out there and it's based on the results of a very recent study by scientists from the Institute of Cardiovascular and Medical Sciences at the College of Medical, Veterinary and Life Sciences of the University of Glasgow in the UK (Whyte. 2013)

Figure 1: Power, workload (top) and metabolic effects of SIT and ES regimen (vs. control; bottom)

When Laura J. Whyte and her colleagues compared the effects of the single bout of very high-intensity exercise (SIT: 4x 30-s maximal sprints w/ 4.5min recovery between each) to a single maximal extended sprint (ES) matched with SIT for work done, they found that the immediate advantage of higher insulin sensitivity (measured via oral glucose tolerance test) in the work-matched continuous sprint the shorter duration 190s (TOTAL!) as well as almost identical...

• decreases is RER and carbohydrate oxitation, and
• increases in fatty acid oxidation

on the day after the exercise bout, in the presence of statistically significant reductions in insulin sensitivity only after the ES trial.

In other words: A single all out sprint on a braked cycle ergometer (as fast as you can; with obviously decreasing power in the course o the sprint) elicits greater metabolic effects within a 85% shorter timespan (198s vs. 1360s!), than work-matched classic HIIT training, with allegedly very long periods of active recovery.

That being said, I strongly caution against taking the results of this study as an incentive to perform the classic "go as fast as you can, for as long as you can" HIT sessions on exercise bikes, treadmills or ellipticals - those SUCK! *full stop* Be smart and either perform that one 3min sprint (if you really have no more time), or modify your HIIT training to incorporate longer high intensity phases (45-90s) at a work to active recovery ratio of 1:3 - 1:2, so that a resulting workout could look like that 4x 60s sprints, interspersed by 120s of active recovery. I would bet money that this protocol outperforms a work-matched continuous sprint in terms of its immediate and long-term metabolic effects.

---

Opioid-like effects of exercise depend on intensity I guess you will be familiar with the term "runner's high"? Now, while the latter is usually ascribed to the exercise induced release of serotonin, the improved affect, the sense of well-being, the anxiety lowering and calming effects of exercise are probably mediated by the release of endocannaboids, of which scientists from the University of Arizona, the University of Texas Health Science Center and the Eckert College in St. Petersburg, Florida, have recently shown that the levels of these endogenous THC-like compounds depends on the intensity of the workout (Raichlen. 2013).

Liar, liar, THC junkie on fire ;-) You don't need to smoke weed before a workout if you get the intensity right! But could exercise also help people who recover from major depression to battle their tendency to obsess with negative thoughts and feelings?

At least in the 10 healthy regular runners who participated in the study, the results of which have been published in the Journal of Applied Physiology the endocannaboid exercise induced increase in circulating anandamide was most pronounced (~2x), when the subjects exercised at ~72% of their maximal heart rate (the workout consisted of 30min of treadmill walking, jogging, running at 45, 72, 83, and 92% of their maximal heart rate). Moreover, the post hoc analysis of the blood samples that had been immediately before and after the workout revealed that exercising at both the lowest and highest intensities had the exact opposite effect, although the reductions in serum anandamide were - when considered in isolation - were not statistically significant.

In conjunction with the results of another recent study that has been conducted at the Stanford University, it becomes evident that these results could actually be more than just "scientific masturbation", so to say. The Stanford researchers compared the reactions of 41 female patients who had recovered from major depressive disorder (MDD) and those of 40 healthy control, both of whom had been randomly assigned to either exercise for 15 minutes or quiet rest, to two sad mood inductions (once before and once after exercise or rest) and found that

"[while r]ecovered depressed participants who had not exercised exhibited higher NA [neagtive affect] after the second sad mood induction [...], both recovered depressed participants who had engaged in acute exercise and healthy control participants showed no increase in NA in response to the repeated sad mood induction." (Hogan .2013)

A reaction that goes against the so-called sensitization effect, which describes the tendency of depressed people (or people with a propensity to develop depression) to react with an increased level of negative effect to a repeated negative stimulus (Eisenstein. 2001) and would thus predict an increase in negative affect in response to the second stimulus as it was observed in the non-exercise group (figure 2, red box).

Figure 2: Negative and positive affect after 1st and second sad mood induction (left) and before and after exercise (right), respectively, in 41 female patients who had recovered from major depressive disorder (data from Hogan. 2013)

Moreover, the 15 minutes of exercise at an intensity the participant felt comfortable with led to an increase in positive affect participants in the exercise groups after the exercise bout, but failed to produce the same beneficial effect on the positive affect in the subsequent double-exposure to the filmic sad mood stimuli:

"However, in contrast to our hypothesis, we did not find any interaction between exercise condition and diagnostic group in level of reported PA following the repeated sad mood inductions that would be consistent with the notion of sensitization or habituation." (Hogan. 2013)

And who knows, if the exercise intensity had been higher, so that there had been more anandamide and other endocannaboids floating around in the brains of the study participants, this could even have changed the positive affect trajectory from the first to the second filmic sad mood induction? "Yo, that's so sad... hahaha" ;-)

---

Image 1: Otsuka Long-Evans Tokushima fatty rats (OLETF, right) have a  genetic disposition to develop type II diabetes.

When metformin is good for the obese (pre-)diabetic and exercise is good, as well, metformin + exercise cannot be bad, right? At least in OLETF rats, one of the common rodent models of the metabolic syndrome, this assumption appears to apply (Jenkins. 2013).

According to the recently published paper by Nathan T. Jenkins and his colleagues, metformin and exercise do in fact work synergistically - at least as far as the obesity induced inflammation is concerned. While metformin decreased the pro-inflammatory overexpression of leptin, the rodents that have been exposed to an endurance type exercise regimen exhibited higher levels of the anti-inflammatory cytokine IL-10, which limit and ultimately terminate inflammatory responses (Moore. 2001).

Not just in view of the fact that IL-10 has also been implicated in the prevention and even treatment of auto-immune diseases, such as lupus erythematosus and multiple sclerosis (Beebe. 2002), I would always choose exercise over metformin - this is all the more true, if you are not morbidly obese in the first place!

And if you want to go even one step further, you simply add couple of interval sprints to the equation as those have been shown - in the same rodent model, by the way - to elicit greater improvements in HbA1c, the long-term marker of glucose management that "classic" steady state endurance exercise (Martin. 2013). Since the latter were mediated via differential microvascular changes than those Martin et al. observed in endurance trained OLETF rats, it is furthermore almost certain that they will add up. Probably not 1+1, but 1.5 and even 1.1 would still be better than 1.0, wouldn't it?

---

The lack of the feeling of  self-efficacy is one of the best predictors of not sticking to a workout routine. And you know what? Oftentimes it's not your your, Joe or Jane who is to blame, but simply their cookie-cutter trainer or unqualified cousin who's dragging them to the gym. Now, think about that... could it be that you are a cousin / trainer like that!? No way, right?

A feeling of accomplishment is one of the main determinants of exercise compliance Have you ever wanted why you really enjoy going to the gym, while your obese cousin will only drag his ass over there if you kick him into the latter? Well, according to the latest study from the Johns Hopkins University School of Nursing and Division of Cardiology at the The Johns Hopkins University School of Medicine in Baltimore, Maryland, it may in fact be you and not Joe or whatever his name is, who is to blame. Probably you are just having him copy what you do, with either way too much weight, or so little weigh that he does not just feel bad about it, but cannot make real progress either (Nam. 2013).

The scientists call that which Joe is lacking a feeling of "self-effiacy", when he is going to the gym training next to his 75lbs lighter cousin, lifting sissy weights and looking like a fat balloon.

No wonder he is falling off the wagon! Specifically, if you also take into consideration that in addition to the missing feeling of accomplishment, which increases his chance of non-compliancy by 19%, Joe also exhibits most of the other features Nam et al. have found to increase the chance of dropping out, specifically,

• low fitness - 26% increased chance of dropout and
• higher insulin resistance - 17% increased chance of dropout,

in the course of their experiment with 140 overweight, sedentary individuals with type II diabetes, who were randomly allocated to a 6-month, 3 times per week exercise intervention or a non-exercise control. And while bodyfatness, i.e. a higher total and subcutaneous abdominal fat percentage appeared to be indicators of higher compliance, when the scientists just looked at the raw data, these positive effects vanished, when they plied a multiple logical regression analysis.

So what's the take home message, here? Cousin or not, people won't do well on cookie cutter plans that won't allow them to make, see and feel progress.

---

Isn't it astonishing how versatile and important these stem cells from the bone marrow are (image NIH. 2001)

1h of exercise thrice a week increases hematopoietic stem cell (HSC) count in the bone marrow With the almost magic effects of stem cell therapy being on everybody's lips, these days. You will probably be intrigued to hear that researcher from the McMaster University have recently established that a very reasonable amount of 3x 1h of exercise per week increased the quantity of hematopoietic stem cells in the bone marrow of exercised mice by +20% compared to their sedentary peers (de Lisio).

With it's likewise statistically significant effect on the proportion of whole BM cells in G(2)/M phase of cell cycle (p<0.05 and an increase in the number of spleen colonies (+48%, p<0.05) in those "model patients" who received transplants from the exercised compared to transplants from sedentary mice, it is thus likely that people who exercise regularly will benefit from both the quantitative increase, as as well as the qualitative improvements these multipotent stem cells, which  give rise to all the blood cell types from the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells), undergo in response to a moderate amount of exercise.

---

Finally acknowledged: "[C]ombination exercise g[ives] greater benefits for weight loss, fat loss and cardio-respiratory fitness than aerobic and resistance training modalities", alone! And this is only the first part of the conclusion of a recently published paper by Suleen S Ho, Satvinder S Dhaliwal, Andrew P Hills and Sebely Pal, who explicitly suggest that

"Therefore, combination exercise training should be recommended for overweight and obese adults in National Physical Activity Guideline" (Ho. 2013)

How the scientists came to that conclusion? Well they could simply have read the SuppVersity news, but instead they conducted a 12-week trial, in the course of which 97 overweight or obese men (n = 16) and women (n = 81) (BMI >25 kg/m² or waist circumference >80 cm for women and 90 cm for men), aged 40 to 66 years, were randomly assigned to a either aerobic, resistance or combined training regimen (n=16 for each) or a sedentary control group (n=15). The results, spoke for themselves.

Figure 3: Changes in body fat (%; top) and VO2Max (bottom) in the course of the 12-week trial (based on Ho. 2013)

In the absence of statistically significant reduction in energy intake, or macronutient composition, the combination subjects in the combination group were the only ones to lose statistically significant amounts of

• body weight (-1.6kg),
• body fat (-1.9kg or 1% body fat), 
• android (=visceral) fat (-1.3kg),

had the most pronounced reduction in waist circumference (-2.6% vs. -2.5% in RT and -2.0 in AT) and were the only ones with statistically significant improvements in VO2Max, a marker of general cardiovascular fitness.

---

Is there maybe more room in your training regimen for slow reps, than you may have thought? If you go by the statement "Slow speed-resistance training induced a greater adaptive response compared to training with a similar resistance at 'normal' speed" from a paper by Mark D. Schuenke and his colleagues from the University of New England, the Rocky Vista University, the College of Health Sciences and Profession and the Ohio-University that was published in the October Issue of the Journal of Applied Physiology (Schuenke. 2013), it would seem so.

If you do however take a closer look at the actual results you realize how important the adjoining qualificatory remark "However, training with a higher intensity at 'normal' speed resulted in the greatest overall muscle fiber response in each of the variables assessed" really is. After all, the "intensity" is per definitionem 20-45% higher in a classic strength training regimen compared to the often laughed at slow-speed resistance training (SS), which was - at least in the study at hand - defined as follows:

• SS: 6-10 reps, super-slow (10s) concentric (no typo!) and slow (4s) eccentric TUT, 40-60% of the individual 1-RM

Both the traditional strength training (TS) as well as the strength endurance regimen (TE) to which this protocol was compared used a TUT of 1-2s on the concentric and eccentric phase, but differed in terms of the weight and rep-numbers, which were

• TS: 6-10 reps at 80-85% 1-RM
• TE: 20-30 reps at 40-60% 1-RM

So, based on the qualificatory remark and a short glimpse on figure 4 you already know that the TS regimen yielded the best results during this 6-week resistance-training program that targeted the quadriceps femoris muscle group, in a total of 17 training sessions (only 2 in the first week), which were supervised to ensure that the 34 young, untrained female participants went to positive failure within the targeted repetition range on all three sets of the three exercises (leg press, squats, and knee extension) they performed after brief warm-up with ~2 min rest between sets and exercises.

Figure 4: Changes in body composition (left) and changes in muscle fiber cross-sectional area (all expressed relative to group baseline; data calculated based on Schuenke. 2013)

What's still missing though is the effect on overall body composition, where the super slow regimen did in fact produce almost identical results, while the "pump" workout ... ah, I mean the "strength endurance workout" sucked here just as it did as far as its effect on the increase in growth the number of hypertrophy-prone type II fibers is concerned.

So what's the take home message here? If you want some diversity, you can incorporate super slow sets into your regimen... but do you have to? At least based on the results of the study at hand, which was unfortunately conducted with untrained young women (who by the way love this alternative training styles) and is therefore not exactly representative for the average advanced trainee, the answer is "rather not, no!"

What neither the advanced nor the rookie who is striving to improve his or her body composition should do, however, is to train in the hilarious strength endurance range of 20-30 reps per set. If you want to build muscular endurance you either go out sprinting, beat the punching bag or do plyometrics.

---

As I know you, you still want more, hah? Well, too much volume is not good for you and in case you cannot wait until next week, there will be some intriguing exercise news in the days to come, probably more on the SuppVersity Science Round-Up with Carl Lanore, on the Super Human Radio Network on Thursday, this week and obviously every day on the SuppVersity Facebook Wall @ www.facebook.com/SuppVersity - like it and always be the first to now!


References:

• Beebe AM, Cua DJ, de Waal Malefyt R. The role of interleukin-10 in autoimmune disease: systemic lupus erythematosus (SLE) and multiple sclerosis (MS). Cytokine Growth Factor Rev. 2002 Aug-Oct;13(4-5):403-12. 
• Eisenstein, E. M., Eisenstein, D., & Smith, J. C. The evolutionary significance of habituation and sensitization across phylogeny: A behavioral homeostasis model. Integrative Physiological & Behavioral Science. 2001; 36, 251–265.
• Ho SS, Dhaliwal SS, Hills AP, Pal S. The effect of 12 weeks of aerobic, resistance or combination exercise training on cardiovascular risk factors in the overweight and obese in a randomized trial. BMC Public Health. 2013 Aug 28;12(1):704.
• Jenkins NT, Padilla J, Arce-Esquivel AA, Bayless DS, Martin JS, Leidy HJ, Booth FW, Rector RS, Laughlin MH. Effects of Endurance Exercise Training, Metformin, and their Combination on Adipose Tissue Leptin and IL-10 Secretion in OLETF Rats. J Appl Physiol. 2013 Sep 27. 
• de Lisio M, Parise G. Characterization of the Effects of Exercise Training on Hematopoietic Stem Cell Quantity and Function. J Appl Physiol. 2013 Sep 27.
• Martin JS, Padilla J, Jenkins NT, Crissey JM, Bender SB, Rector RS, Thyfault JP, Laughlin MH. Functional adaptations in the skeletal muscle microvasculature to endurance and interval sprint training in the type 2 diabetic OLETF rat. J Appl Physiol. 2013 Aug 23.
• Moore KW, de Waal Malefyt R, Coffman RL, O'Garra A. Interleukin-10 and the interleukin-10 receptor. Annu Rev Immunol. 2001;19:683-765.
• Nam S, Dobrosielski DA, Stewart KJ. Predictors of Exercise Intervention Dropout in Sedentary Individuals With Type 2 Diabetes. J Cardiopulm Rehabil Prev. 2013 Sep 24.
• National Institute of Health (NIH). Stem Cell Information Webpage. June 17, 2001. < https://stemcells.nih.gov/info/2001report/chapter4.asp > retrieved on Oct 01, 2013.
• Raichlen DA, Foster AD, Seillier A, Giuffrida A, Gerdeman GL. Exercise-induced endocannabinoid signaling is modulated by intensity. Eur J Appl Physiol. 2013 Sep 19.
• Whyte LJ, Ferguson C, Wilson J, Scott RA, Gill JM. Effects of single bout of very high-intensity exercise on metabolic health biomarkers in overweight/obese sedentary men. Metabolism. 2013 Sep 19.

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. 2013b), 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. 2013).

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. 2013b) -- 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. 2013 and Hackney. 2013)

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. 2013) -- 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. 2013)

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. 2013)

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). 2013a 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. 2013b Dec;35(11):947-50.
• Ozen, SV. Reproductive hormones and cortisol responses to plyometric training in males. Biol Sport.2013; 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. 2013;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.