Training Tip Tuesday #9- A Look at Running Economy: Part 3

I hope everyone had a great thanksgiving and has had some time to work off that delicious turkey, gravy, dressing, sweet potatoes and pumpkin pie! Actually, I contend that thanksgiving food is relatively healthy if it weren't for the enormous quantity we feel compelled to consume. How is meat, potatoes, maybe a salad and some rolls bad for you? It's the sheer volume of food that does us in and lays waste to our ambitious holiday goals of staving off the ever reproducing lipids appearing about our torso. Oh well, whatever you ate for thanksgiving I hope it was delicious and enjoyed with friends and family!

To continue our discussion of running economy I will finally divulge what Saunders et al., concluded can actually be done to improve RE. 

1) Altitude exposure

There are various mechanisms that researchers believe may play a role in lowering RE with altitude exposure. However one thing is for sure- numerous studies have found a lower VO2 (oxygen) during a steady state test in athletes following 3 weeks at altitude. The performance gains are well proven but exactly WHY or HOW isn't as conclusive. Studies have shown that Kenyan runners (living and training at altitude) did not "accumulate lactate during running until near very high or peak exercises intensities, and had much lower lactate both at altitude and sea level at high relative exercise intensities." This was in comparison to Scandinavian runners who lived and trained at sea level. One of the reasons for this is thought to be the greater skeletal muscle oxidative enzyme capacity exhibited in Kenyan runners which shifts their metabolism from anaerobic to aerobic. Easier said than done altitude training obviously has it's benefits but the expense and length of time you must remain at altitude doesn't make it a viable option for most of us to improve our RE.

2) Training in the Heat

Slightly easier to attain for those of us living in Texas, a mildly elevated core temperature is thought to increase RE by "increasing the efficient of the working muscle." Heat training promotes an increase in plasma volume and decreased blood viscosity. Another adaptation is the ability to run at a given speed with lower heart rate and core temperature following a period of heat training. For most of us, heat training isn't a choice in the summer and I don't recommend post-poning your runs until 3:00 pm during a warm July day just to accomplish this benefit. The article doesn't state what temperature constituted "heat" training but I'd be willing to guess it isn't 110 degrees that is relatively common for a Texas summer day.

3) Strength Training

NOOOOOOOOOOOOOO… I can nearly hear the moans emitting from my laptop speakers. For the most part, us triathlete HATE strength training. And I totally understand and can sympathize with the time-crunched triathlete who is having a hard enough time fitting in three sports a week much less a fourth. Well, the studies are in and other than helping injury prevention (another benefit I think strength training has), strength training can and WILL help you run faster. I apologize for the slightly wordy quotation but I think Saunders et al., summarizes things much more nicely and intelligently than I can-

"Endurance athletes must be able to sustain a high average running velocity for the duration of a race." (That's called going as fast as we can for a long time) "This emphasizes the role of neuromuscular characteristics in voluntary and reflex neural activation, muscle force and elasticity, running mechanics, and the anaerobic capacities in elite endurance runners.” (Helps your brain and sympathetic nervous system fire muscles quickly so you can go fast).

This strength training can be either in the form of heavy-weight training or plyometric type explosive-training. Both have their place and their advantages.

Heavy-weight strength training was shown to enhance RE in well trained triathletes (average VO2max of 69 mL/kg/min, which is very high). If it’s benefitting very high level athletes who are already operating further towards the ceiling of their performance capabilities then chances are it can benefit you as well. A great example of someone promoting this in our local San Antonio community is Jen Rulon, of Endurance-Fit. I highly discourage jumping into deadlifts and deep squats if you don’t have a personal trainer or someone who can coach you in the proper technique.

Plyometric training is very popular with sprinters, throwers, football players and other power athletes but it also has its place in the endurance community. By enhancing the muscles ability to generate power and promoting storage and use of elastic energy plyometric training can help a runner produce more force “without a proportionate increase in metabolic energy requirement.” Basically, you can push off the ground harder and faster without using more oxygen. A good thing! Plyometric training is a little easier to do on your own or with a coach because all you need is some space and lots of sweat. Here are a few basic, introductory drills and plyometrics for runners.

The area of strength training is one I think triathletes and runners have the most room for improvement. If strength training can elicit significant performance gains from elite athletes who are at the very tip of the their ability than it will definitely help beginner, intermediate and advanced triathletes as well. 

Training Tip Tuesday #8- A Look at Running Economy: Part 2

Last week we discussed what (the deuce) running economy is and why it is an important marker for endurance performance. Being able to use our precious oxygen in the most economical way possible is extremely advantageous whether we be racing sprint triathlons or Ironman. Originally I was going to talk about how we can improve RE this week but after further review of the material I've decided to extend this discussion one more week. This week I'll be covering some of the various biomechanical, physiological and anthropometric characteristics that effect RE. This doesn't necessarily mean you should start employing an intervention method to enhance RE. It's simply a sampling of variables that effect RE. NEXT week I'll talk about specific interventions that might help you improve yours. There is one in particular that is easy to implement and carries a host of benefits. Below, I've highlighted a few of the interesting and relevant factors effecting RE. Once again, the Saunders article is my primary source along with some confirmation from various other articles.



Anthropometric Characteristics

I'll place my bet on skinny calves all day long

Since none of us have control over how tall we are, how wide our pelvis is or the size of our feet I'll brush over these factors relatively quickly. The biggest take away is that less body mass on the extremities is conducive to better RE. Small calves are better than big calves when it comes to running fast. This is also part of the reason we wear lighter weight shoes in racing. Less mass at the extremities means less effort to move that mass and less oxygen required.

Physiological Factors

It's generally accepted that a higher percentage of slow-twitch muscle fibers is associated with better RE. We'll touch on this more next week when we discuss specific interventions to improve RE but more running results in an increase in oxidative mechanisms and enzymes. From the Saunders et al., article- "An increase in the respiratory capacity of skeletal muscle permits trained runners to use less oxygen per mitochondrial respiratory chain a given sub maximal running speed." Quite a mouthful I know but the takeaway is this- improving our aerobic energy system makes us more economical.

Stride length

Research has shown that RE is best with a self-selected stride length during running. That is, RE gets worse when subjects consciously tried to shorten or lengthen their stride different from how they normally stride when running. I don't think this has to mean that we should never try to adjust our stride. Most of these studies were done on well trained individuals running at a speed of 8-10 mph (7:30-6:00 min/mile pace. For a well trained runner that is a fairly relaxed pace and they have undoubtedly run hundreds and hundreds of miles at that pace and become very economical. Below we'll discuss the difference between over striding and heel striking. I believe that correcting over striding is a good thing. There is also a difference in whether our stride length comes from in front of us or behind us. If you aren't already running sub 7:00 or 6:00 min/mile pace for a half marathon than don't completely throw the idea of adjusting stride length out the window.

Footstrike

Oddly enough, HEEL STRIKERS were found to have better RE than forefoot strikers! Utterly shocking and utterly conflicting with what is the current day trend of forefoot running. Personally, I don't think HOW the foot hits is the ground is quite as important as WHERE it hits the ground in relation to our center of mass. I will try not to climb on too much of a soap box here but I definitely think this point deserves note. There is a difference between heel striking and over striding. Over striding is bad, heel striking isn't necessarily bad.  I don't think the issue of over striding should be fixed by focusing on what part of our foot touches the ground first but where the foot touches the ground. Many elite runners are known to be heel strikers and I know of at least one extremely successful triathlon coach who actually tries to coach his athletes to become heel strikers.  It's a point worth considering anyways.

Flexibility

No consensus was found on this issue. Some studies found that improved hip flexion and extension resulted in improvement in RE. Many others have found that poor flexibility actually resulted in better RE. This is thought to be due to better elastic return of energy because of stiffer joints, muscles and tendons. My personal belief is that there is an appropriate level of flexibility and that each person is different. Some people are naturally quite flexible and don't need specific stretching exercises to stay that way. Others, I think, can benefit from stretching muscles around the hip that allow them to have full range of motion during their running stride. If tight hip flexors are preventing you from extending fully at the toe off phase of your run stride then you might benefit from stretching your hip flexors.


I want to be careful in mentioning these various variables that coerce to generate running economy. Many of them might seem contradictory. For instance- if a self selected stride length is best then why might flexibility and increased hip extension improve my RE? None of what I've outlined above are interventions that should be taken to augment RE. I will cover that next week. In the meantime I wanted to paint a broader picture of the issue in hopes of eliciting better understanding. Another confounding is that each individual is different with a different physiological, anthropometrical (I just feel really smart typing that word) and biomechanics make up. Even among elite runners there is a wide discrepancy in stride mechanics, muscle fiber type and flexibility. My goal is to educate and elicit thought.

ipsa scientia potestas est

Knowledge itself is power

Training Tip Tuesday #7- A Look at Running Economy: Part 1

Ahhh running economy. That elusive, mystic enigmatic variable we have heard reference to but aren't quite sure exactly what it means. We shall attempt to delve into the intricacies of this nebulous term and hopefully come out better informed and wiser on the other side. In this post I will do my best to explain the definition of running economy, what it measures and the implications thereof.

Much of the information on running economy I will present today comes from a review article titled, "Factors Affecting Running Economy in Trained Distance Runners (Saunders, Pyne, Telford & Hawley 2004)." In their article, Saunders et al., summarizes the information on running economy gathered from over 100 pieces of literature. For the purposes of this post I will be mainly referring to the Saunders, piece. If you have questions about the other sources and references please feel free to contact me and I will be happy to provide the references for you.

What the deuce is running economy, you ask? Well, allow me- "Running economy (RE) is typically defined as the energy demand for a given velocity of sub maximal running." Say whaaa???? To put it more simply, running economy is essentially how much oxygen we use to run at a given speed. RE is measured at a much lower speed than maximal intensity because it's not very applicable to see how efficient we are with oxygen while sprinting. The reasons for this are 1) because sprinting 100m has little to do with the aerobic energy system and 2) because we don't sprint a 5k, 10k or marathon off the bike. It is much more applicable to find out how efficient we are with oxygen while running 10k pace or half marathon pace than running 4:00 minute pace for 200 meters.

An example protocol for testing RE would be to have all subjects perform a 10min run at 8 mph (7:30 pace). During this run the subjects VO2 and respiratory exchange ratio (RER) would be measured. (RER shows what percentage of fat versus carbohydrate our body is using for fuel. An RER of 1.00 reflects 100% carbohydrate utilization to fuel the working muscles). Having better running economy basically means that we need less oxygen to run at a given intensity. I don't know about you but I'm all for conserving every spare O2 molecule I have when I'm racing hard trying to beat the fellow next to me.

This helpful little graph from the Saunders paper shows how two elite level runners can have nearly identical values for their VO2max but have drastically different running economy (and different 10k times).

With RE it isn't about how fast or how far you can go, or how high your VO2max is, It's about how efficiently you can use the resources (oxygen) you have while running at a given intensity.

This is important because racing is all about efficiency. The goal of a race is to get to the finish line as fast as we can. Now, if we can conserve energy by being more… dare I say economical? This will allow us to go faster at the same level of effort.

To put it another way- lets say my "threshold" intensity is 50 mL of oxygen per kilogram of body weight per minute (mL/kg/min) and I can run 7:30 pace at this intensity. If I can improve my running economy so that I only have to use 45 mL/kg/min of oxygen to go 7:30 pace, that means that I can now bump my intensity back up to 50 mL/kg/min (my threshold) but I'm now running 7:15 pace instead of 7:30 pace. I'm running at the same intensity but my pace is faster at that intensity because I'm more economical That means I'm going faster and more likely to beat you!!

Hopefully this exiguous attempt at analyzing running economy was somewhat enlightening and didn't confuse the issue more. Next week I'll discuss ways we can improve running economy. In the meantime feel free to chime in with comments, questions, complaints or disagreements you may have.

Until next time!

Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004). Factors affecting running economy in trained distance runners. Sports Medicine, 34(7), 465-485.