On my mind #4

Tacking on a full-time, professional grad program after finishing up my PhD has meant some sacrifices to my research program. That being said, I’ve been fortunate to have some great (and understanding) collaborators, and I’ve had a few articles go live in the last few months.

Effects of age and unaccustomed resistance exercise on mitochondrial transcript and protein abundance in skeletal muscle

This article represents a large chunk of my PhD thesis. Previous work in patients with mitochondrial diseases had found that muscle regeneration [1,2] and/or strength training [3] could alleviate mitochondrial mutational burden . This lead to the theory of mitochondrial gene shifting, where “fresh” mitochondrial DNA (mtDNA) is “donated” to myofibres stimulated and/or damaged by resistance training when satellite cells fuse with them as a part of the repair/regenerative process [4]. This model is particularly appealing given that mtDNA deletions and mutations increase with age [5-11] and are therefore thought to contribute to the aging process as a whole [12-14]. Strength training may then promote optimal mitochondrial aging through the provision of “fresh” mtDNA on a regular basis.

We thought to look at this concept in an acute model (single session) of resistance training [15]. Even though, contrary to popular belief, there can be mitochondrial benefits to strength training, predominantly in the elderly [16-22], our data found a general reduction in mitochondrial transcript, protein, and DNA abundance, suggesting an immediate reduction in mitochondrial content. We’d like to hypothesize that this was related to the pruning of sub-par mitochondria, that would then be followed by amplification of the “fresh” mitochondria from satellite cells, but have no data to support this assertion at this point.

Read more here.

Daily chocolate milk consumption does not enhance the effect of resistance training in young and old men: a randomized controlled trial

I was fortunate to have the chance to collaborate with Dr. Stu Phillips and his lab for this paper [23]. Recently we’ve seen some great work from Brad Schoenfeld and Alan Aragon discussing the importance, or perhaps lack thereof, of a post-exercise “anabolic window” to the hypertrophic adaptations to training [24,25].

Consistent with their work, chocolate milk consumed immediately post-exercise during twelve weeks of strength training did not enhance muscle growth in either young or older men compared with training with isocaloric, carbohydrate control. This seems to fit the ideology that overall nutritional status and consumption has a larger impact on the hypertrophic adaptations than the immediate consumption of specific macronutrients in the peri-workout period, at least within a one-hour post-exercise period and controlling for total protein intake [25].

Read more here.

Effect of repetition duration during resistance training on muscle hypertrophy: a systematic review and meta-analysis

I have to admit that I’ve never been a huge proponent of complex tempo prescriptions for hypertrophy, having never seen any convincing evidence that it was necessary. That being said, lifting with slow tempos, to purportedly maximize time under tension and therefore hypertrophy is one of the most common recommendations circulating in the popular press. In this article [26] I teamed up with Brad Schoenfeld and James Krieger to analyze whether the data supports slow tempos, and what we found was that when concentric failure is used as an end-point, there is a wide range of tempos that support muscle growth.

If someone recommends specific tempos to optimize or maximize growth, it’s probably worth asking them for a citation or two.

Read more here.

Cardio Kills

I told myself when I started the site to resist the urge to become the online fitness industry’s unpaid fact checker, as is often the case for those who push an evidence-based approach. That being said, a now not-so-recent article titled “Cardio Kills” made the argument that chronic endurance exercise would, through various mechanisms including the production of reactive oxygen species, result in damaged and/or shortened telomeres. Others have ripped the article apart, but I haven’t seen someone address the telomere argument from the article – and it’s definitely worth addressing.

Telomeres are specific repeating sequences that are required to allow DNA polymerases to copy the full-length of a DNA sequence, as they require a few base pairs to run through to ensure the end of the sequence is properly copied. Now telomeres act as a biological clock of sorts as many replications means lots of copied DNA but each run makes telomeres just a little bit shorter (approximately 60 bp). Run out of telomere and the next thing you know is your DNA polymerases can’t copy the good stuff in your DNA with the same fidelity as when there were telomeric sequences that gave them room to run. Next thing you know your cells are in a state of replicative senescence.

Telomere Length

So this article takes the stance that free radicals produced during endurance, presumably along with increased replicative demands, damage and shorten telomeres, and your lifespan as well.

Unfortunately the argument here relies on indirect, physiological mechanisms to support a position while ignoring any data on the actual outcome of interest, that is, the effects of endurance exercise on telomere length. Surely if the argument holds true, studies on endurance athletes should demonstrate reduced telomere length, but they don’t [27-30]. Only Rae et al [31], who found comparable telomere length between runners and sedentary individuals, displayed a negative relationship between years and hours of running on minimum telomere length in DNA extracted from skeletal muscle. There are limitations in the data, such as the reliance on cross-sectional designs on relatively small sample sizes along with variability in the cell-types studied (leukocytes, skeletal muscle), but you’d be hard pressed to turn the existing evidence base to suggest that endurance exercise is reducing telomere length, or to an extent that would represent a risk of premature mortality.

This indirect argument, that free radicals from the elevated metabolic demand during endurance exercise can damage telomeres and therefore “Cardio Kills” doesn’t hold true when we look at data on the actual outcome of interest.

Let’s not forget that exercise in general has a positive effect on, or is associated with reduced mortality [32], and that arguments of detriment often consider higher volumes of near exhaustive or exhaustive exercise. Telomere length also isn’t a single component system and exercise can stimulate telomerase activity, which can act to maintain telomere length depending on the tissue [33]. Finally, the same, supposedly detrimental effects of endurance exercise (replicative demands and free radical production) also occur with strength training.

Spending a few years surrounded by endurance athletes while completing my PhD may have made me soft on endurance athletes, but in this case, while there’s definitely room for further investigation, the existing data just doesn’t support the argument.

So while their shorts may be too short, their telomeres probably aren’t.

Wishy-washy scientists

I’ve recently become more interested in knowledge translation, or more specifically, how can I make evidence-based recommendations appealing to a general audience, not just other researchers and professionals. I’ve been a long-time follower of Tony Gentilcore’s blog, and a recent guest post by Tony Bonvechio caught my attention.

The post dealt with tips to become a better fitness writer, to which there is no shortage of articles. In this one, Tony has a collection of useful tips, including learning how to correctly cite research, but I found the one on ambiguous writing as it relates to conveying research findings most interesting. I’ve screen captured the article and the two example statements are shown below.

Wishy washy scientists

The first statement (“Research suggests…”), if referenced correctly, while appearing “wishy-washy”, actually conveys very specific information about the underlying studies that were used to formulate the argument. The sentence structure indicates that there were likely two separate studies, one showing that deadlifting induces growth of the glutes and hamstrings, and another study that made a connection between size of the glutes and hamstrings to faster sprint speeds. This also indicates that it likely wasn’t a single study whereby deadlifts were observed to increase hypertrophy of the glutes and hamstrings that occurred alongside increased sprint speed.

The second sentence (“Deadlifts can make…”) would indicate an entirely different structure for the argument, mainly that deadlifts have been shown to improve sprint speed in a single study.

In the examples above, deadlifts may relate to glutes and hamstring growth, and glutes and hamstring size may be related to sprint speed, but deadlifts weren’t directly shown to contribute to sprint speed. The second example suggests that they were. Keep in mind these are hypothetical examples, but the point here is to highlight the structure of the argument and not whether there is underlying data to actually support the claims themselves.

So what’s “wishy-washy” to some, is actually pretty damn precise to others. For me, the question that’s really raised here is how do we acknowledge the limitations of the underlying evidence for our arguments while presenting the information in a way that is both actionable and appealing to the audience?

Does there have to be a trade-off between accuracy and audience appeal?

Doing what it takes versus

Anyone who follows me on Twitter knows I’m a huge fan of Cal Newport’s work on his blog “Study Hacks”. In fact, the one book I consistently recommend to pretty much anyone who emails a question even remotely related to career development is his 2012 book “So good they can’t ignore you” . If you don’t already own it, it’s well worth the money.

In this article, Cal recounts the story of Nobel laureate Eric Betzig, who had to reconcile a desire for a job in academics with a less than stellar publication record after a few years out of the scientific community. Instead of continuing to do what he had always done, Betzig asked what it would take to achieve his goal, and set to work to make it happen.

This story has parallels to any profession. In the fitness industry, I often get emails asking whether a degree or a certification is necessary to be a personal trainer. It doesn’t end there, is this book, course, seminar worth the cost? While my credentials probably make my answer obvious, and contrary to my opinion there are certainly individuals who are successful without these, what I really feel is being asked is can I get what I want by doing what I already know how to do.

Donotlink.com

I stumbled across this site as a recommendation in the comments section of one of Bret Contreras’s recent “Grill the Guru” posts. It’s well known now that authors take very polar stances on topics to generate traffic, as they capture both those who agree, and garner even more attention from those who they’ve “enraged” with their supposed controversial content.

Now if donotlink.com works as it claims, which is for somebody that is more technologically savvy than me to figure out, you still have the evidence-based pile on you enjoy, while not boosting the ranking of the article in search engines at the same time. In reality, this seems like a pivotal tool to the evidence-based movement. You can still link and initiate discussion on the pseudoscientific garbage that people use as link bait, but at the same time limit its spread not having your linking to it increase its search engine rank. 

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Dan Ogborn