Thursday, 2 January 2014

Evidence Based Resistance Training Recommendations for Muscular Hypertrophy

Two years on from our 2011 review titled 'Evidence Based Resistance Training Recommendations' and me and my colleague and friend James Fisher were sat chatting over coffee as we often do on our lunch breaks. We had been reading alot of the excellent recent review articles regarding hypertrophy from people like Brad Schoenfeld but had some concerns regarding recommendations stemming from these articles. Many of the recommendations appeared to be heavily influenced by acute studies measuring proxy markers of hypertrophy or utilising methods that do not consider whole muscle hypertrophy such as biopsy.

So we decided we should set about conducting a similar review of training studies utilising what we considered to be the most valid means of determining muscular hypertrophy in order to provide a set of recommendations that we considered to be best supported by the available evidence. 

So here is that review paper, covering the same areas as our previous and a few additional ones.
Evidence Based Resistance Training Recommendations for Muscular Hypertrophy
ABSTRACT 
Objective: There is considerable interest in attaining muscular hypertrophy in recreational gym-goers, bodybuilders, older adults, and persons suffering from immunodeficiency conditions. Multiple review articles have suggested guidelines for the most efficacious training methods to obtain muscular hypertrophy. Unfortunately these included articles that inferred hypertrophy markers such as hormonal measurements, used older techniques that might not be valid (e.g. circumference) and failed to appropriately consider the complexity of training variables.
Methods: The present commentary provides a narrative review of literature, summarising main areas of interest and providing evidence-based guidelines towards training for muscular hypertrophy.
Conclusions: Evidence supports that persons should train to the highest intensity of effort, thus recruiting as many motor units and muscle fibres as possible, self-selecting a load and repetition range, and performing single sets for each exercise. No specific resistance type appears more advantageous than another, and persons should consider the inclusion of concentric, eccentric and isometric actions within their training regime, at a repetition duration that maintains muscular tension. Between set/exercise rest intervals appear not to affect hypertrophy, and in addition the evidence suggests that training through a limited range of motion might stimulate similar results to full range of motion exercise. The performance of concurrent endurance training appears not to negatively affect hypertrophy, and persons should be advised not to expect uniform muscle growth both along the belly of a muscle or for individual muscles within a group. Finally evidence suggests that short (~3 weeks) periods of detraining in trained persons does not incur significant muscular atrophy and might stimulate greater hypertrophy upon return to training.
It's already received some attention across the interwebz via reddit and Chris Highcock has offered some down to earth thoughts on the main point to be drawn from the article here

The main variable that can be manipulated in a resistance training program that likely has the biggest impact upon both strength and hypertrophy is effort. As long as this is high enough by attempting to train to momentary muscular failure, everything works. Just do what fits your personal preferences best and make it sure it is safe.

Monday, 16 December 2013

Deconditioning and Low Back Pain

The recent review that came from my PhD work examined the exercises most effective for conditioning the lumbar extensors. We have another paper presently in review examining many of these exercises, particularly ILEX, with respect to outcomes in those suffering from CLBP (pain, disability, GPOs etc.). However, much of my present work is based upon the assumption that specific deconditioning of the lumbar extensor musculature is a predominant factor in LBP, both prospectively and cross-sectionally. Hence why we are looking at ways to most effectively condition the musculature for prevention, and arguing that such specific exercises may be most effective in treating CLBP.

The research on 'disuse' and 'deconditioning' in LBP is vast, and very conflicting. Many do not find the hypothesis very convincing for this reason - you can pull a number of studies out to either support or refute it. However, there are a number of issues with prior studies and reviews on the topic. 'Disuse' and 'Deconditioning' are often not distinguished between and this lack of distinction in definitions often influences discussion of the concept. In addition most reviews have not considered all possible methods of examining the hypothesis, both prospectively and cross-sectionally. 

So, one of the first things I set out to do during my PhD work was to begin accumulating all the evidence available that had looked at the deconditioning hypothesis in LBP, as it specifically related to the lumbar extensor musculature. Over the first couple of years of my studies I looked for research meeting my broad inclusion criteria for answering the question of whether lumbar extensor deconditioning was associated with LBP, and whether this might be causative. This culminated in reviewing a vast number of studies, many of which it became apparent had a number of methodological issues which likely caused the conflicting results. After considering all the available evidence though in the context of its strengths and weaknesses it did seem that there was something to the 'deconditioning hypothesis' as it pertained to lumbar extensor deconditioning specifically. 

After all the time spent reviewing this area and writing about it we have finally had a version of the reviews manuscript accepted and published. 
Publishing this piece proved difficult due to its size. I wasn't prepared to scrimp on quality or cut out studies that might be relevant so finding a journal prepared to accommodate our manuscript, assuming it passed peer review, was an extra challenge in itself. The final piece will also include an extensive appendices summarising every study considered in the review which further added to its length.
Here is the abstract and link to the paper as a Just Accepted piece (I'll update when the copy-edited version is available).
A Reappraisal of the Deconditioning Hypothesis in Low Back Pain: Review of Evidence from a Triumvirate of Research Methods on Specific Lumbar Extensor Deconditioning
Objective: ‘Disuse’ and ‘Deconditioning’ in relation to low back pain (LBP) are terms often used interchangeably. Discussions of ‘disuse’ refer to general physical inactivity, which evidence suggests does not differ between symptomatic and asymptomatic persons. ‘Deconditioning’ refers to a decrease in function, commonly both cardiovascular/aerobic fitness and muscular strength/endurance again noting little difference. However, examination of decreased function relating specifically to lumbar extensor musculature deconditioning has yet to be examined corroborating all possible methods. Thus, this review attempts reappraise the deconditioning hypothesis in LBP specifically considering lumbar extensor deconditioning.
Methods: A literature review was conducted examining both cross sectional and prospective data on specific lumbar extensor deconditioning and LBP. A narrative approach and ‘snowballing’ style literature search was used involving initial use of PubMed and Google Scholar databases searching up to December 2012. Included where studies utilising the following three research methods allowing specific induction of the role of such deconditioning; 1) strength/endurance testing of the isolated lumbar extensor musculature, 2) imaging and histochemical examination of the lumbar extensor musculature, and 3) fatigue testing of the lumbar extensor musculature using electromyography.
Results/Findings: Despite issues interpreting individual studies due to methods, the majority of evidence suggests LBP is associated with decreased strength/endurance, atrophy, and excessive fatigability of the lumbar extensors. Prospective studies also suggest lumbar extensor deconditioning may be a common risk factor predicting acute low back injury and LBP.
Conclusions: The hypothesis of specific lumbar extensor deconditioning as being a causal factor in LBP is presently well supported. It is by no means the only causative factor and further research should more rigorously test this hypothesis addressing the methodological issues highlighted regarding previous studies. However, its role suggests specific exercise may be a worthwhile preventative and rehabilitative approach.
This piece hopefully brings the deconditioning hypothesis back to the table for debate where at present there seems to be little consideration of it within the academic literature - it seems to have been already dismissed. Our conclusion is that it does present a quite robust account of LBP, though likely not the only one.
In considering other areas such as human evolution there is further corroboration for the role that weak lumbar musculature might play in LBP. This is what I discussed at the Ancestral Health Symposium earlier this year.
At the moment our work is further trying to understand the role the lumbar extensors play in LBP, and also how specifically addressing them might impact those who are symptomatic. LBP is associated with a number of dysfunctions and we are trying to see how lumbar extensor dysfunction sits in a multifactorial consideration of LBP. It does seem to be a factor, though as with any hypothesis this is still open to more thorough attempts to disprove it, and there is also a lot more we have yet to examine with regards to predictions from the hypothesis.



Friday, 8 November 2013

What Exercise is Best for the Lumbar Extensors?

Ok so things have been pretty hectic for me at the moment. I am coming to a critical point in my PhD work, I have been moving about regarding jobs, and have had plenty of other projects on the go. Hence little activity on the blog recently. 

I have a few posts lined up and will get to them in the near future. In the meantime I wanted to highlight the paper that we have just had published. As most may be aware my PhD research involves the use of a specialised form of exercise for the lumbar extensors that utilises a specific restraint system in order to prevent concurrent hip extension and thus involvement of the hip extensor musculature during the exercise. Although in theory this should make for a more specific means of exercising and thus conditioning the lumbar extensors to date no one has reviewed the literature in this respect, nor have they compared studies examining other exercises aimed at conditioning the lumbar extensors.

So as part of my PhD literature review I wanted to examine whether or not evidence showed that isolated lumbar extension (ILEX) was indeed more specific in conditioning the lumbar extensors. Understanding this may go some ways towards understanding the mechanisms through which such exercises are effective at reducing pain and disability in CLBP as it seems ILEX is more effective than unrestrained trunk extension (see Smith et al., 2011).

As a note, and this is discussed in the article, ILEX is essentially allowed by having the pelvis restrained against a posterior pelvic restraint,  a semi-seated position and thigh belt, such as in the picture below.


So we first reviewed the literature pertaining to what effects different exercises aimed at conditioning the lumbar extensors had upon acute activation of this musculature. Although acute activation measured using EMG is not necessarily indicative of the effectiveness of a particular exercise or approach in inducing chronic adaptations it is a good place to start to generate hypotheses or to understand mechanisms. 

Finally we reviewed the literature pertaining the to what effects different exercises aimed at conditioning the lumbar extensors had upon chronic adaptation of this musculature. These studies give us the real information regarding how specific exercises may or may not be for conditioning the lumbar extensors.

Here's the abstract: 
A review of the specificity of exercises designed for conditioning the lumbar extensors
Abstract
Objective To review the specificity of exercises designed to condition the lumbar extensor musculature (ie, lumbar erector spinae and multifidus).
Methods A review of studies examining effects of exercises designed to condition the lumbar extensors was conducted. Included were studies that examined the acute activation and chronic adaptation of the lumbar extensor musculature in response to benches and roman chair trunk extensions, free weights exercises (ie, deadlifts, squats, good-mornings, etc), floor and stability ball exercise (ie, trunk extensions, bridging, four-point kneeling, etc) and resistance machines (ie, those with and without pelvic restraints).
Results Evidence suggests that the reviewed exercises designed to condition the lumbar extensors all may result in significant activation of this musculature during their performance. However, examination of training studies shows that for benches and roman chair trunk extensions, free weights exercises, floor and stability ball exercise and resistance machines without appropriate pelvic restraints, evidence suggests that they may be less effective for inducing chronic adaptations in the lumbar extensors as a result of their performance. Contrastingly, resistance machines that employ appropriate pelvic restraint to isolate lumbar extension are better evidenced to confer specific adaptations to the lumbar extensors.
Conclusions Numerous exercise approaches have been designed with the intention of conditioning the lumbar extensors. Those examined appear to activate the lumbar extensors; however, the specificity of many of these exercises for producing chronic adaptations may be questionable, potentially due to the compound nature of them allowing involvement of other musculature such as the hip extensors. Many of the reviewed exercises offer potential to condition the lumbar extensors, however, isolation of lumbar extension through appropriate pelvic restraint appears important for optimising specific adaptations in the lumbar extensors.
The results of our review indeed did suggest that ILEX may be most optimal for conditioning the lumbar extensors, however, some of the other exercises examined (particularly trunk extension based movement i.e. roman chair, swiss ball or floor trunk extensions, deadlifts, other 'unrestrained' back extension machines) may induce some degree of conditioning the lumbar extensors. It just might not be as effective as ILEX.

This publication was timely with respect to another in British Journal of Sports Medicine recently. We highlighted in our review that the ability to identify which exercises were most specific for the lumbar extensors may be important from a prehabilitative perspective. A few days later the following study was also published indicating the effectiveness of resistance training in preventing injury:
The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials
Abstract
Background Physical activity is important in both prevention and treatment of many common diseases, but sports injuries can pose serious problems.
Objective To determine whether physical activity exercises can reduce sports injuries and perform stratified analyses of strength training, stretching, proprioception and combinations of these, and provide separate acute and overuse injury estimates.
Material and methods PubMed, EMBASE, Web of Science and SPORTDiscus were searched and yielded 3462 results. Two independent authors selected relevant randomised, controlled trials and quality assessments were conducted by all authors of this paper using the Cochrane collaboration domain-based quality assessment tool. Twelve studies that neglected to account for clustering effects were adjusted. Quantitative analyses were performed in STATA V.12 and sensitivity analysed by intention-to-treat. Heterogeneity (I2) and publication bias (Harbord's small-study effects) were formally tested.
Results 25 trials, including 26 610 participants with 3464 injuries, were analysed. The overall effect estimate on injury prevention was heterogeneous. Stratified exposure analyses proved no beneficial effect for stretching (RR 0.963 (0.846–1.095)), whereas studies with multiple exposures (RR 0.655 (0.520–0.826)), proprioception training (RR 0.550 (0.347–0.869)), and strength training (RR 0.315 (0.207–0.480)) showed a tendency towards increasing effect. Both acute injuries (RR 0.647 (0.502–0.836)) and overuse injuries (RR 0.527 (0.373–0.746)) could be reduced by physical activity programmes. Intention-to-treat sensitivity analyses consistently revealed even more robust effect estimates.
Conclusions Despite a few outlying studies, consistently favourable estimates were obtained for all injury prevention measures except for stretching. Strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved.
So there we have it. Strengthening looks to be most effective for reducing injuries in sport and being that ILEX is most specific in conditioning the lumbar extensors may be best for reducing low back injuries and LBP. Though prospective ILEX exercise has been used in occupational settings and shown reducec low back injury rates ideally future work should look to actually conduct prospective interventions utilising follow-ups to rigorously test this in athletic populations. 

Obviously not everyone has access to equipment capable of providing ILEX but they shouldn't fret. Utilising some type of trunk extension exercise and attempting to focus on lumbar extension through the movement will likely provide some degree of conditioning and some is better than none in this respect.


Tuesday, 3 September 2013

Do Resistance Machines Increase Risk of Developing Low Back Pain?

I caught the following paper after Martin Berkhan shared it.

Are flexibility and muscle-strengthening activities associated with a higher risk of developing low back pain?

I initially commented on facebook the following:
"Umm 'observational cohort study' - maybe people with back pain are more likely to use resistance machines because other exercises exacerbate their pain? Haven't read the full text yet but the abstract conclusions are misleading "...use of weight training machines is associated with increased risk of developing low back pain compared to use of free weights..." The word 'developing' should be 'reporting' as this misleading gives an indication of temporal direction which this study can't determine."
I've managed to get hold of the full text now and read through so I thought I'd comment on it here as although the authors wordings may not be as misleading as I first thought, there are still issues with the study (or at least how it is reported) that give cause for concern with such strong conclusions.

The vague reporting in the methods section leaves me with a number of questions. In essence the researchers in the study drew upon data from he Aerobics Centre Longitudinal Study (ACLS) for reanalysis in order to examine the incidence of LBP in those using muscle-strengthening and flexibility exercises. Participant data was used as long as they had undergone at least 2 medical examinations as part of the ACLS between 1977 and 2005. Participants with a number of morbidities reported during their last examination were excluded so that the population consider was essentially healthy. The authors also report that they excluded any participants who reported LBP at 'baseline.' During examinations participants were asked to indicate yes/no as to whether they had ever had a problem with LBP or whether they were currently suffering from it. They were also asked to answer the following questions:

  1. "Are you currently involved in a muscle-strengthening program?"
  2. "Can you specify the muscle-strengthening activity as "Callisthenics", "Free Weights", "Weight Training Machines" or "Other"?"
  3. "Are you currently involved in exercises to maintain or improve your joint flexibility?"
  4. Can you specify the flexibility activity as "Stretching", "Callisthenics", "Exercise Class, "Yoga" or "Other"?"
Now the reason I italicised 'baseline' is because based upon the methods and the reporting of their results it is very difficult to discern when, relative to the follow-up period, baseline actually was.

The population were followed for  4.9+3.8 years. The results notes that 'new incidence of LBP' was reported and examined, however it is not indicated during what examination (out of the 'at least 2' across the follow-up) this data was taken from relative to the baseline nor how many examinations were even conducted on average for each participant. So we have no idea as to 'when' over the follow-up period LBP was actually reported and based upon the incongruity between the question asked for determining the presence of LBP reported in the methodology (ever had a problem with LBP or currently suffering from it) and the reported 'new incidence of LBP' it is difficult to discern.

As baseline reporting of LBP (whenever baseline indeed was) was considered exclusion criteria it is reasonable to conclude that any relationship between baseline variable and LBP at follow-up (whenever that indeed was) was prospective, despite not knowing any more details. 

So what relationships were reported? At baseline there were differences between those reporting that they engaged in either muscle-strengthening or flexibility exercises compared with those who did not. Generally those engaging in either were 'healthier' across a range of markers in their health examination. However, what was not reported was whether within the groups engaging in muscle-strengthening or flexibility exercises there were any other differences between those using different approaches.

The researchers did however adjust for many of these health markers in 3 other models and found quite consistently that those reporting they engaged in muscle-strengthening using either weight training machines or 'other' methods were significantly more likely to report LBP ('new incidence' or past problems is unclear?). Stretching exercises also significantly increased the likelihood of reporting LBP though the results were not as consistent across the models.

Though the analyses of these relationships appears robust enough my concerns about the lack of clarity in the methodology for reporting of LBP, and thus the validity of the data collected, leaves me questioning this. It's unclear to me as to whether this relationship is indeed truly longitudinally prospective and that for whatever reason engaging in exercise using resistance machines increases risk of 'developing' LBP. Despite the authors comments in the discussion regarding free weight exercise potentially doing a better job of strengthening the paraspinal musculature there is actually little to no evidence to suggest that they are indeed better at doing so. The conclusions are also extremely broad in nature and do not consider the specific exercises engaged in. There are very likely exercises, both free weight and machine based, that when compared to others are either better or worse in terms of development of LBP. It would have been interesting to understand what 'other' methods of muscle-strengthening were used also in order to better speculate regarding a potential mechanism for how LBP might develop from engagement in both resistance machines and 'other.'

All in all this study in my humble opinion doesn't really tell us very much and it concerns me that it may put people of the use of resistance machines for reasons not wholly valid.

Thursday, 22 August 2013

Ancestral Health Symposium 2013 - Back from Atlanta!

I got back on Monday from Atlanta after me and my girlfriend Emma attended the Ancestral Health Symposium 2013. I was attending in order to present but really it was so much more than that. The event was enjoyable for a variety of reasons not the least the chance to meet a number of people who until now have only existed as online personas via scientific articles, blog posts, twitter/facebook feeds and online video. 

AHS13 was very much about bringing the movement, it's people and their ideas together IRL (in real life). I'm not going to labour the point or try to recap everything I saw, everyone I met etc. There were so many valuable moments that I couldn't do them all justice. 
Everyone I met you all know who you are - and we had an awesome time!! (or at least I think we did - great food, tequila and sexy Farm Burger tattoo's anyone?). Anyone I didn't get the chance to meet - see you next year!!
But in all seriousness, a few key things were the chance to discuss my research and idea's with other knowledgeable people - or put them to test really and see if they stood up to their scrutiny. On the way to Boyd Eaton's house for dinner with the inimitable Ben Sima driving (not word used often but Ben is inimitable enough that I've seen him use it more than once -Great to finally meet Ben who I've been in email contact with for a while - He was a really driven, inquisitive, and overall awesome guy), along with Miki Ben-Dor and his partner we discussed our respective research for our Ph.D.'s, what we were presenting at the conference, and general life as a Ph.D. student. 

I managed to meet with Aaron Blaisdell, David Pendergrass and Paul Jaminet - all co Editor's-in-Chief for the now officially launched Journal of Evolution and Health. This was a great opportunity as I will acting as an Associate Editor for the journal offering my expertise particularly in area's relating to exercise physiology. Speaking with them about the future for the journal and what we can all do to make it succeed was great.

There were so many awesome talks of high caliber in terms of academic content with a number of MD's, Ph.D.'s and Ph.D. candidates presenting (alongside a number of also very high caliber presentations from practititioners, bloggers and laypersons). AHS is really 'growing-up' so to speak and maturing into a proper academic conference. Hopefully this along with the newly launched journal will give it greater standing in the academic communities.

My talk went well, according to those who watched it, but I was left feeling like I tried to include to much which ended up being skimmed over towards the end. I would have loved the opportunity to get into much more detail and next year will definitely be more ballsy making sure to request a 40 minute slot.

As Peter Ballerstedt said to me one morning - When you give a talk there are really three - The one you planned to give, the one you gave, and the one you wish you gave. Meeting Peter was great too. We sat next to each other at breakfast and even though it was a short discussion both me and Emma found him to be the pinnacle of friendliness as he shared some interesting factoids and stories with us (Peter, if you read this, honestly if I mention you Emma responds immediately with how nice she thought you were).

Anyway, all this years presentations will be made available online on the AHS YouTube channel soon enough including my own so you can all judge it for what it's worth. In the meantime I've uploaded the slides and my abstract with a full reference list (there are 240 references in total cited throughout the presentation -see how I struggled to keep it to 20 minutes now) to dropbox for anyone who wants to get a head-start . As always any questions shoot me an email.
To those who have emailed me in the past month or so who I haven't replied to yet, I haven't forgotten you, just been very busy. I've kept any messages and will get round to them as soon as I can.
I've already decided and begun planning what I want to present next year (assuming they will; have me back again). Hope to see as many of you as possible in California next year!!

Thursday, 25 July 2013

Examine.com - Supplement Goals Reference Guide



I've been so rammed with work over the past few months that I've had little time to spend writing any blog posts despite having a number I'm itching to get done.

Anyway I've a good reason to fill the interlude now with an independent recommendation.

Supplement Goals Reference Guide

Examine.com have been around for only ~2.5 years so far but they have already set themselves apart as the leading resource on nutrition and supplement information.

I was contacted by Sol Orwell, one of the co-founders, a little over a year ago and introduced to Examine.com. Since then he's been one persistent mofo in keeping in contact with all their latest updates and changes. Every email I get from him brims with enthusiasm and he's got every right to be enthusiastic.

I've been using Examine.com personally now for the past year as my go to resource for nutrition and supplement information. The fact that the supporting studies are linked makes it so much easier to follow up the evidence and check to see if the recommendations are valid. I've recommended it to my students and to my colleagues at the University who have also been utilizing it. It really is the most comprehensive, unbiased, science based resource available. And now they've made it even more user friendly with the release of their Supplement Goals Reference Guide.

Please head over and check it out:

The Supplement Goals Reference Guide

Also head over and check out Chris Highcock's interview with Sol to get a feel for the motive power behind this.

Friday, 12 April 2013

Letter to the Editor - Controlling Resistance Training Variables in Interventions for Chronic Nonspecific Low Back Pain

Spine have just published online a letter I submitted to the Editor regarding a recent publication by Willemink et al. which I discussed on this blog earlier in the year.
If anyone would like a copy please contact me.
The letter highlights my concerns with the authors conclusions in light of the methodology employed and follows on to a degree from the letter I wrote in response to Steiger et al. last year in European Spine Journal.

The main issues refer to the poor control of resistance training variables, in particular the intensity of effort, load and also frequency.

In their paper Willemink et al suggest that adaptations on the multifidus musculature are not related in any way to clinical improvement i.e. pain and disability. However another issue with their methodology relates to the lack of control group. Their training protocol was likely insufficient to induce muscular adaptation anyway, but it is also not possible to rule out that the clinical improvements may have been due to placebo type effects.

I think it is premature to suggest that changes in muscular morphology or performance are unrelated to clinical improvements at present. Especially when our own research utilising very specific isolated lumbar extension exercise has just reported that improvements in isolated lumbar extension strength are in fact significantly related to clinical improvements.