Thursday, August 7, 2014

Are we on a Quest for Mitochondria or a Quest for Maximized Performance?

What I don’t understand is when I see teams and athletes pursuing marginal gains and ignoring the basics and fundamentals of sound training. There is no sense pursuing the last 2% until you have taken care of the first 98%.
-Vern Gambetta
As science advances, we identify transcription factors and map cellular signalling pathways in clinical settings to potentially maximize muscles' oxidative capacities. While mitochondrial biogenesis and angiogenesis are undoubtedly important for improving a muscle fiber's resistance to fatigue, we have to ask - should these be the target or the byproduct of training?

In other words, is it practical and worthwhile for athletes to manipulate their environments and diets in search of additional stress? What effect might this have on performance? An interesting review has been published recently: Link Here

The review from Baar is focused on using the available molecular knowledge to potentially maximize the activity and number of PGC-1a to stimulate mitochondrial biogenesis and angiogenesis. Essentially, maximizing metabolic stress through manipulation of an athlete's diet. The review notes that prolonged, low intensity training in fasted, glycogen depleted states and calorie restriction may maximally activate PGC-1a, as does training >75% VO2max.

This reminds me of the stories I've heard about cyclists filling their tires with sand or mounting lead filled water bottles on their bikes in an effort to make training harder. But in reality, the athlete could just ride harder and faster without the hassle of these unique "training aids."

I can't help but think dietary manipulation (calorie restriction, glycogen depletion) is much like these training aids. Yes, they will likely make training more difficult - increasing metabolic stress at a given workrate or pace - but could the athlete work harder or go faster without the intervention? How much is a rider's power output going to decline if he trains in a fasted state? How will it affect tomorrow's training? Do you put the athlete at a greater risk of illness? What's more important here - training for mitochondria or training for performance?

As my mentor Dave would say at the end of the day, "mitochondria don't win races, power outputs do."

Looking beyond the molecular aspects of training and beyond anecdotal reports, we have little research on the effects of training in a glycogen depleted state on performance. A few marathoners used periodic low carbohydrate training in preparation for the London marathon, but as this was a case study, there was no control group. And yes, many east African distance runners may voluntarily or unknowingly train in depleted states - but I have yet to see research indicate that their VO2max values are higher than those of runners from other cultures.

The potential of maximizing metabolic stress without added mechanical stress is appealing, particularly for runners, whose training volume may be limited by mechanical stress. And perhaps it can be appropriate as part of a periodized approach, but we should not forget that mechanical stress is also a stimulus for adaptation. More research is needed to address the effects of glycogen depletion/fasted state training on performance - Isn't performance the goal?

Tuesday, August 5, 2014

Endurance Training: Running vs. Cycling

A lot of people ask me, "What's the biggest difference between training for running and training for cycling?"

The simplest answer is that an athlete should have so much more opportunity to suffer on the bike.

If a runner's training not limited by time, motivation, or illness; what is it limited by?
It's fatigue and the ability to recover from previous workouts. If recovery was not a limiting factor, he could go out and run 3+ hours, or complete intervals at 5K race pace day after day without the fear of injury or exhaustion.

What about the cyclist? Yes, fatigue is a real thing for the cyclist; but mechanically, cycling is very different from running. During cycling an athlete experiences very few eccentric muscle contractions.

Meanwhile, the runner is constantly subjecting his quadriceps, hamstrings, hip and plantar flexors to impact forces and eccentric muscle contractions. These eccentric contractions cause muscle damage, in turn causing muscle soreness. Muscle soreness may alter stride mechanics (Tsatalas et al., 2013), decrease economy (Baumann et al., 2014), making running fast more difficult and potentially leaving runners vulnerable to injury.

So, the muscle damage incurred during running puts limits on the volume of work that can safely be completed by the runner.

To demonstrate my point, here's an 8 day block of training aimed at increasing maximal sustainable power output (MSPO), for the cyclist:

Cycling
Day 1 - 6 x 5:00(5:00) @ 110% MSPO
Day 2 - 5 x 2 x 3:00(90) @ 115-120% MSPO, 8:00 between sets
Day 3 - 5 x 4 x 90(60) @ 120+% MSPO, 6:00 between sets
Day 4 - off
Day 5 - Easy 60-75:00
Day 6 - Easy to Moderate 90:00 - 2 hrs
Day 7 - 6 x 5:00(4:00) @ 110% MSPO
Day 8 - 5 x 2 x 3:00(75) @ 115-120% MSPO, 6:00 between sets

This is nothing outlandish for many cyclists, but outside of Canova's one or two day, "special blocks." Have you ever seen a runner complete a block of training like this? If you have, I'd love to hear about it. The closest thing I can think of is the training of Brenda Martinez from Joe Vigil (HERE). Even that schedule on the bike would not be very daunting.

You'll never see professional runners complete the same amounts of volume as professional cyclists. Cyclists will log 3-6 hours in the saddle a day, even the best marathoners will not equal this volume. And you'll never see a running stage race like that of the grand tours - simply because no runner could survive 3 weeks of 3-6 hours of racing/day - not at the same intensities (I'm not talking about some multiple day charity jog).

So, why then don't we see more block training from runners? The technical answer is eccentric muscle contractions. But simply put, it is the product of common sense and trial and error - the risk of injury is too great.

I will not deny that there could be potential in block training for runners, but with careful manipulation. I think there are components athletes and coaches can transfer across disciplines, but you can't simply mimic cycling training if your a runner and vice versa.

Friday, August 1, 2014

Uncoupling Proteins, Metabolism, Economy

What if I said, overweight people have the potential to be very good endurance athletes. Or you could say; very good endurance athletes are especially susceptible to becoming overweight when they're no longer training for competition.

Well, this is largely rooted in speculation, but for curiosity's sake - stay with me.

The theory is based on mitochondrial efficiency, or how well the electron transport chain can create and maintain a H+ concentration gradient across the inner mitochondrial membrane. This concentration gradient is used to drive ATPsynthase to generate ATP. If you had a leaky membrane and you were losing hydrogen ions, you'd be losing that gradient you worked so hard to create. Like trying to fill a bucket with a hole in the bottom, you'd have to turn up the water (substrate) to get it to fill up.

Uncoupling proteins essentially act as holes in the mitochondrial membrane, allowing protons to pass through them without harnessing their potential energy and this makes the electron transport chain less efficient - requiring more substrate to create "X" amount of ATP.

Depiction of an uncoupling protein releasing H+ from intermembrane space
Now consider the inverse relationship of VO2max and economy (here and here).

Could uncoupling proteins be the culprit? How does training effect mitochondrial efficiency? Could obese people just be really efficient at making ATP? Does it matter?

Further reading:
http://www.ncbi.nlm.nih.gov/pubmed/24336883
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1805795/
http://www.ncbi.nlm.nih.gov/pubmed/23084644
http://www.ncbi.nlm.nih.gov/pubmed/18845781