More On Levels and Zones

An example of a power duration curve in WKO4

I had a few people ask for some explanation on my comment about training levels being more descriptive, not prescriptive in the last article “Not So Secret Sauce.”  I thought it would be helpful to explain and to expand a bit more on training levels, zones, and threshold to help athletes and coaches have a better understanding of these concepts.

Why zones and levels?  Seems redundant right?  Actually there is a fundamental difference in how we define these.  Levels are descriptive and used in post ride analysis.  They tend to be broader than training zones, and have some dependency on the workout as a whole. For example, an endurance training level may be anywhere from 200 – 265 watts, but we may want an athlete to be more at the lower end versus the higher end of that range depending on the goals of the workout.

Technically we really only have 3 levels: above Threshold (anaerobic), between aerobic and anaerobic (between threshold), and aerobic.  In other words, this is easy, moderate, or hard.  Of course there are transitional zones between these that can elicit different responses.  This is where training zones start to come in.  Zones are prescriptive and include how hard and for how long.  As technology evolved we started to have ways to provide more detail and specificity.  This detail allows us to hone in on specific aspects of fitness adaptation.  To achieve these definitions of zones we had to have an anchor that varied by fitness.  Thus threshold (however you want to define it) became the anchor as the alternative of anchoring at “max” wasn’t as accurate.  Whether you are using heart rate or power, anchoring your training zones at threshold will provide you a lot more accuracy in your training.

These are the traditional training levels created by Dr.Coggan

These are the traditional training levels created by Dr.Coggan anchored by threshold in level 4.

With power becoming more prevalent, we were able to test as often as we would like to set accurate functional threshold numbers.  You didn’t need to travel to a lab to find out where VO2, lactate threshold, or any other physiological number was at.  You could easily go out and do a test to figure out where your functional threshold is and set your training levels optimally.

One important note: functional threshold power is really a surrogate power for maximal metabolic steady state and does have its definition rooted in physiology, but is much more actionable and  predictive of success in sport than a lab derived number like VO2. 

As a definition, functional threshold is the max power or pace you can maintain for an hour.  Doing an hour-long effort can be technically challenging (where to do a steady state 1-hour effort, pacing, fueling) that we often use a 20-minute test done after an all-out 5-minute effort to exhaust anaerobic ability and then take ~95% of that 20-minute effort to determine threshold.  We could then use that functional threshold number to create individuality in our training levels as well as track changes in fitness over time.

Sea Otter CX

This works well for about 80% of the athletes out there.  In a typical bell curve application, the 10% of the athletes on either end need a bit more customization.  This is where using diagnostic tools can be very helpful in determining those outliers and creating a more individualized approach for those athletes that fall outside the bell curve.  Individualization is one of the core training principles and is the key to increasing training efficiency and effectiveness (I will write more on the other core training principles in the future).  It is defined as training that recognizes the unique physiology of the individual athlete.

One of the most powerful diagnostic tools we currently have is the power duration curve for cyclists using power.  This is essentially what is your maximal workload for any time frame.  While this is an extremely valuable and informative chart for cyclists with power, the core principle can be applied to all athletes even if not using power, heart rate, or any training metrics.  Essentially, your maximal intensity will decrease as time duration increases.  All athletes can produce a higher output for 5 minutes than they can for 10 minutes.  Most coaches have used this principle in prescribing workouts for shorter durations for quite some time.  In athletes using heart rate, we often wouldn’t even prescribe a specific heart rate for efforts less 5 minutes due to the limitations of how heart rate responds.  Instead, we would have athletes do close to maximal efforts for the prescribed duration.  There are some limitations to this, but it often works well for those athletes not using power.  In runners, I have also found that running pace on flat ground or normalized graded pace in the hills is a good proxy for power and while fundamentally a bit different, the same power duration curve principles apply.

An example of a power duration curve in WKO4

An example of a power duration curve in WKO4

Back to cyclists that have power, using the power duration curve allows us to customize power prescriptions for workouts based off their unique physiology and not off generalized percentages of threshold.  Don’t get me wrong, using percentages of threshold is pretty accurate for efforts up to and including threshold workouts but when we start working on those efforts that are higher than threshold percentages don’t give us a level of specificity that respects the individuality of the athlete.  For example, we may have two athletes at the same threshold power but one can produce 10% more power at 5 minutes than the other.  Prescribing a 5-minute effort based off a percentage of threshold for those two athletes would produce two different workouts and two different results from that workout.

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Achieving this level of individualization was the goal of Dr.Coggan in using the concepts of the power duration curve to create iLevels.  This gives us 9 training zones based on the data from the power duration curve.  Before the release of the iLevels, we would often have to look at mean maximal powers for a variety of durations to set prescribed powers in workouts.  Now we have the very robust iLevel algorithm that does a lot of that work for us.  There is still some need to tailor the prescribed powers and durations for athletes, but the heavy lifting is done.

iLevels

iLevels

Using the power duration curve we are also able to phenotype athletes, or defining the specific type of an athlete.  Some cyclists are TT specialists while others are road sprinters and others are all-arounders.   Defining the type of the athlete is useful in guiding training and better preparing them for the demands of their goals. For athletes that are using heart rate, we tend to use performance results from races, group rides, and rider feedback to phenotype an athlete and get an idea of where their strengths and weaknesses lie.  While this is significantly less precise than what we are able to do with power it can still be a very powerful tool in individualizing training for an athlete.

Hope that explains a bit more the function, definition, and value of training zones as well as highlight the heightened specificity that results from using a power meter.  Training with heart rate or even perceived exertion can still be very effective, but it is hard to beat the added specificity and individuality that training with power can give us.

Happy Training!

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Interbike 2015 Part 2

Open U.P.

In case you missed it, I covered the latest on power meters and a few other technical items from interbike earlier this week here.  This is the post on of the other fun things seen at interbike plus a few other bits of tech.

Between the fit symposium, technical power meter reviews, and discussions over new fitness products we are able to sneak in some time to check out some cool new bikes and products.  This year didn’t disappoint either.  There was plenty on convention floor that count our attention and we were stoked on to try.  There were a few other things that had us shaking our heads as well.  Here is a little bit of both.

Open U.P.

Open U.P.

Open’s U.P. (unbeaten Path) 650b cross bike with full 2.0 mountain bike tires, or 700c x 40 cross tires, was one of the first bikes to catch our attention.  Not only was the concept of an adventure cross bike with more capable tires pretty rad, the attention to detail on this bike was amazing.  Direct mount disc brakes, fully internal cables and hydraulic lines, top bag adventure mount, and through axles to keep the frame stiff all made this bike one of the top of the show for us.  

Merckx EM525

Merckx EM525

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More on the road side, the Merckx EM525 was another bike that really caught our attention.  The disc brake DI2 bike had swoopy clean lines, with internally routed cables and hydraulic lines, as well as direct mount disc brakes (which is thankfully becoming the standard).  

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One of the more awesome displays was Bradley Wiggins hour record-setting TT bike on display at Pinarello.  This had to be one of the sleekest TT bikes I have seen.  Every detail was meticulous on this bike down to the 3-d printed custom aero bars used by Wiggins to set the record.  _DSC5568

A bit more on the tech side, new GPS computers were everywhere at the show with Wahoo, Lezyne, and Garmin showing off new bar mounted units.  The new Wahoo Elemnt is their first computer that can work as a standalone unit and doesn’t have to be paired with your phone, although there is some pretty awesome features on this one when you do have it paired including map integration with third-party services like Strava, and direct upload of workout files to Garmin connect, Training Peaks, or Strava.  The Elemnt can also pair with power meters and heart rate straps via ANT+ or bluetooth.

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Lezyne debuted a full suite of GPS computers including the mini GPS (10 hour of battery lift and 40 hours of recording), the Power GPS (22 hour battery life with 200 hours of recording time), and the Super GPS  (22 hours of battery life with 400 hours of recording time).  The Mini GPS is just a simple GPS cyclometer with no power or HR integration, the Power GPS has bluetooth connectivity but no ANT+ (ironically making the Power GPS not compatible with a lot of power meters on the market), and the Super GPS can do both bluetooth and ANT+.  All of the Lezyne computers look like a nice option for a small, simple computer that can give you solid core functionality.  

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Last but not least, Garmin was showing off the compact 25.  This being the smallest GPS computer I have seen, it was nice to see that it still has bluetooth connectivity for heart rate straps and works on the more sensitive GLONASS GPS system for better accuracy.  At this point it doesn’t have any power meter integration (though they indicated that might happen for bluetooth enabled PMs through a firmware update at some point) not ANT+ integration.

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One of the more ridiculous things I saw at the show was WTBs new lock on grip system that requires cutting your bars at a 45 degree angle to allow for the locking mechanism.  To cut your bars you will need a special tool that fits into a standard Park Tool steerer cutting guide.  Alternatively, WTB makes a special bar to use with these grips as well.  I still don’t know why this is any better than a standard clamp on grip…  A close second in the ridiculous category is Rotor’s hydraulic drivetrain.  While impressive from an engineering standpoint, electronic drivetrains is where it is at…

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A few other quick notes in general:

  • Electronic integration in bikes is continuing to progress.  Electronic drivetrains, wireless drivetrains, electronic wireless mountain bike dropper posts, and electronically controlled lockouts for dual suspension mountain bikes have continued to progress and finding their way on to more and more bikes. _DSC5591
  • As a whole, the cycling industry has really stepped aerodynamic technology.  No doubt driven by Specialized who has led the industry in aerodynamic advances (it helps having your own wind tunnel).  
  • Matte paint (preferably high vis and black) for road, cross, and mountain bikes is definitely the new trend.  Norco bikes had some of the best looking bikes all with matte paint treatments. _DSC5574
  • The better the shoe, the brighter the colors.  At least that is the theme at Sidi, Scott, Giro, and Shimano.  Also, laces are rad!
  • Lastly, Cross Vegas is awesome and this year was made all the better with it being the opening round of the UCI World Cup.  20150916_220555

 

Full gallery of photos here!

Racing at Altitude

Donner Pass

This has been an interesting year with mountain bike, elite road, and masters road national championships being held at altitude.  Throw in races like Ironman Tahoe, Ironman Boulder, Leadville 100, lots of  XC mountain bike races, and events like the Death Ride and it is becoming very common for athletes to do at least one event a year at higher elevations.  For those of us living at lower elevations, racing at higher elevation events can be very challenging.  Not only do we see a decrease in aerobic capacity at elevation but pacing, nutrition, and hydration are all more complex at elevation.  Estimating how altitude will affect you as an athlete as well as the metabolic changes are very important in an athlete’s race preparation.

Monitor Pass

East Side of Monitor Pass

Most of the research done on the effect of altitude in athletes was conducted before the 1968 Olympics in Mexico City (approx. elevation of 7400ft).  The consensus from the studies concluded that an athlete loses 2% of VO2 for 1000ft above the first 1000ft.  So what does that mean to actual performance?  Bassett et. al. (1999) did a comparative analysis of cycling world hour records to put those loses of aerobic capacity into power terms for both acclimated and unacclimated athletes.

Bassett formula For acclimated athletes, in % of zero elevation power:

y = -1.12x^2 – 1.90x + 99.9 (R^2 = 0.973) where x=elevation in km

Instead of having to do all that math, here is an easy to read chart on the results from the Bassett study:

Effects of Elevation

To put these into a real life example, if you were traveling to Truckee CA for Elite Road Nationals (~6000ft) a day before your event you would expect to experience a 11.1% drop in aerobic performance.  However, if you were able to spend extra time at elevation and become acclimated your aerobic performance would only drop 7.3%.  For an athlete with a sea level of threshold of 300 watts that is an almost 12 watt difference.  While that may not seem like a lot, it can be huge when trying to make that breakaway stick or going up that final climb at the end of a long hot race.

Donner Pass

Donner Pass

The big question for a lot of athlete is how long does it take to acclimate?  This where things become a little fuzzy.  Several studies have been done on acclimatization all showing a pretty wide variance of individual responses.  What we can conclude from these studies is that most athletes will need at least 2 weeks of altitude exposure and a maximum of 4 weeks to become complete adapted.  This is assuming adequate iron and B vitamin stores.  If either of those are low than adaptation to altitude will be slower and potentially incomplete.  If you are targeting an event at elevation it may be useful to get a blood test done to ensure you have adequate serum ferritin, folate, and B12 levels.

Since most athletes can’t afford to spend up to a month at altitude before an event, we are seeing more and more athletes getting altitude tents to help with acclimatization.  Altitude tents are essentially tents that go over an athlete’s bed and a device that lowers the oxygen content to create a hypoxic environment.  This stimulates the lower oxygen absorption rate experienced at altitude and can help in the adaptation process, however in my experience the total time to be maximal adaptation from an altitude tent is about double the time needed at constant altitude exposure.  Also, having optimal levels of iron and B vitamins is crucial in making this adaptation since the altitude tents primarily only alter hematological levels and don’t address the other physiological adaptations to altitude (breathing rates, reduced blood volumes, etc.).  It is also because of this that we see slightly lower acclimatization rates from altitude tent use than full altitude exposure.

Altitude Tent

Altitude Tent

One important factor to keep in mind while spending time at altitude is that while your aerobic system is improving to the increased demands at altitude, muscular power will decrease due to the reduced workload.  Essentially power, not heart rate, will be limited at altitude compared to what is possible at lower elevations and provide less stress to the muscles.  Over time that can result in less anaerobic or sprint power.  That is very important to take into consideration in that final preparation.  If your event requires a lot of anaerobic power it may be important to include some trips to lower elevations to work on more powerful shorter duration efforts to maintain that ability.

Altitude not only affects aerobic capacity, it also can have a large affect on your fueling and hydration plan.  For longer events like Ironman races, maximal VO2 is almost never a limiter.  Instead we see metabolic fitness, how quickly and for how long can your body create energy, becomes a bigger limiter in athletic performance.  There has only been a few studies on how metabolism is affected by altitude, but what has been done shows a shift to higher carbohydrate metabolism for any given work rate.  This makes sense since relative intensity goes up as elevation increases at any given work rate.

The actual increase in carbohydrates varied by over 8 percent, but typical results showed an average 20% more carbohydrate utilization at 7500ft compared to 2500ft.  The larger and more fit the athlete resulted in a bigger metabolic effect on athletes.  Smaller, less fit athletes are less metabolically affected.  Just as with aerobic function, becoming acclimatized to the higher altitudes will also affect the metabolic shift.

This metabolic shift in carbohydrate oxidation is very important for 70.3 and Ironman athletes.  Just as it is important to adjust a long course athlete’s pacing strategy to account for reduced aerobic capacity, it may also be important to reduce intensity to spare carbohydrate stores.  Beyond acclimatizing to the higher elevation, working on becoming more metabolically efficient may also have a huge impact on performance.  Through a combination of diet manipulation and specific training it is possible for athletes to increase the amount of fat they burn at any given intensity.  This is a pretty complex topic and something I will cover in a separate article in the near future.

Road Nationals finish at 6700ft

Road Nationals finish at 6700ft

Hydration also becomes a bit more difficult at altitude since the absolute humidity decreases as you go up in elevation.  It isn’t uncommon to see absolute humidity in the mid to low 30% range which would increase fluid loss through respiration and may increase sweat rate.  One of the biggest preventable issues I see with athletes competing and training at altitude is dehydration.  Nothing will slow you down faster than becoming dehydrated and it is a huge risk at higher elevations.  It isn’t uncommon for endurance athletes to go through 20 – 32 ounces of fluid an hour at altitude. That is 2 big bike bottles for every hour of exercise!  With that much fluid it is important to pay attention to electrolyte content as well to avoid becoming hyponatremic.  I would recommend using a product like Salt Stick tabs, or Skratch Hyper Hydration to maintain sodium levels with the increase fluid intake.  It is also important that you maintain hydration outside of your sport as well.  I recommend that all athletes start the day with 16oz of water with electrolytes (salt stick tabs, Nuun, 1/4tsp good quality sea salt, or trace minerals) and never go anywhere without a water bottle when at elevation.

Since there is quite a bit of individual variance in responses to altitude it is important for athletes to work out their individualized plan.  Of course if you have the time spending 2 – 4 weeks at your favorite mountain resort is by far the best option, just not very practical for most of us.  Another useful strategy is to minimize altitude exposure leading up to an event and going up as late as possible before an event.  While this doesn’t help to become physiologically adapted, it does limit some of the short-term negative effects of altitude.  It is common to see performance decline rather rapidly the first few days at elevation, then it slowly starts to come back up as the body becomes adapted.  Going up the day before or day of an event can limit the initial decline in performance and be a better plan than going up 2 – 4 days before an event.

However you approach events at altitude, make sure you make a plan and address the unique demands of these events.  Some of my best racing experiences have occurred over 5000ft and I wouldn’t of enjoyed them as much without addressing the unique demands of performing at altitude.  Maybe it is time for you to join the athletic mile high club…

Leadville 100

Leadville 100

Myth of Pedaling Circles

Pioneer has some of the best pedaling metrics in the market.  This is a good example of data from elite athletes in national level events.

How many times have you read an article in your favorite cycling magazine about how the key to your cycling success lies in pedaling better circles?  It seems every spring and early summer we start seeing articles explaining the benefits of pedaling circles and if you are concerned with performance you need to stop mashing the pedaling to increase efficiency.  Usually included in these articles are some fancy one leg-pedaling drills that not only help you improve your pedaling, but also show you how weak and inefficient you pedal your bike.  Surely professional cyclists and triathletes must pedal perfectly round circles….not really.  The reality is that the fitter the athlete, the more they mash on the pedals.  Pedaling circles is just a myth and trying to do it may actually be hurting you.

“It appears that ‘elite-national class’ cyclists have the ability to generate higher ‘down-stroke power.’  Compared with group 2 (amateur group), group 1(elite group) also produced higher peak torques and vertical forces during the down-stroke even when cycling at the same absolute work rate as group 2.”- Physiological and bio-mechanical factors associated with elite endurance cycling performance. Coyle EF et. al.  1991

Wait a second, how can that be when we have products like Computrainer showing fancy graphs that my spin isn’t perfect and Power Cranks to help me fix my spin?  Marketing has never lied to me before, how could this happen?!

Power Cranks

This is a pretty common conversation I have had with athletes over the last several years.  With power meters dropping in price and providing more data, the question of how to best pedal a bike has come up over and over again.  There is so much miss information on this that I think it is important to put out what science has said on the myth of pedaling circles.

Pioneer has some of the best pedaling metrics in the market.  This is a good example of data from elite athletes in national level events.

Pioneer has some of the best pedaling metrics in the market. This is a good example of data from elite athletes in national level events.

Before we dig deeper into the studies, I think it would be beneficial to go over a bit of biomechanics and physiology.  Cycling is essentially looking at hip and knee extension and flexion as you pedal. Extension in cycling is essentially pushing down, while flexion is the upward phase of the pedal stroke.  There are other smaller muscles and joints involved but to keep this somewhat simple we will just look at the knee and hip. Extension in the hip and knee primarily uses the gluteus maximus, hamstrings, and quadriceps.  Flexion in the knee and hip primarily involves the hip flexors (psoas, iliopsoas) and rectus femoris.  Before we go any further, it is pretty obvious that the extension muscles are quite a bit physically bigger than the flexion muscles.  If we also think about how we use those muscles most of the time, extension is used to push against gravity while we really only use the flexion muscles to lift up our leg.  The amount of force to lift our bodies is always going to be more than it takes to lift our leg and this is the first blow against the myth of pedaling circles.  Unless you have very weak extensors, it is impossible for the muscles responsible for flexion (pulling up on the pedals) to produce equal force as the extensors.  That would be required to provide meaningful power to the pedal stroke since in pedaling both legs are connected through the crank and bottom bracket.  As your left leg pushes down it in effect lifts your right leg as well.  At best, all you can really do is lift the weight of your leg on the upstroke.  Metabolically speaking, there is no difference in your left flexors lifting the leg or your right extensors pushing the left leg up as long as you aren’t still actively pushing down with your left leg.  We are moving the same mass the same amount so the energy cost is exactly the same.

Yep, his hip flexors are totally bigger than his quads...

Yep, his hip flexors are totally bigger than his quads…

Even though it is the same metabolic cost, pulling up on the pedal stroke can still be problematic.  The primary hip flexors, psoas and iliopsoas, originate on the transverse process and body of the T12 – L5 vertebrae.  Essentially the pull on your lower back.  If you are using the muscles extensively they can start to fatigue your lower back and lead to a lordotic curve in your lumbar spine.  This is often a cause of lower back pain in cyclist and triathletes.  Furthermore, if you are a triathlete that is fatiguing the hip flexors on the bike by trying to pedal circles it will be even harder to lift your legs up on the run which can have a huge impact on performance, getting full hip extension, and maintain proper posture.  In extreme cases, pulling up on the pedals can even lead to an impingement on the iliac artery leading to numbness and a loss of power.  Even if you aren’t a triathlete, over activation of hip flexors and the resulting tightness of the muscle group can result in anterior pelvic tilt, lordotic back, and lower back pain.  Not of that is athletic, powerful, or attractive.  Seriously, anterior pelvic tilt does not bring sexy back.

Anterior Pelvic Tilt

When we look at the independent studies down on cycling bio-mechanics the picture is pretty clear.  Pedaling circles results in impaired performance, loss of efficiency, and potentially increases the risk of injury. In a literature review by Simon A Jobson, et. al. (Gross efficiency and cycling performance: a brief review. 2012) it was concluded that  “‘pedalling in circles’ allows pedaling to become mechanically more effective, this technique does not result in short-term improvements in gross efficiency.”  In another study by Korff T, et. al. (Effect of pedaling technique on mechanical effectiveness and efficiency in cyclists.) they found that “When the participants were instructed to pull on the pedal during the upstroke, mechanical effectiveness was greater (index of force effectiveness=62.4+/-9.8%) and gross efficiency was lower (gross efficiency=19.0+/-0.7%).”  What really matters is gross efficiency since that is the net result of your physiological energy propelling the bicycle.

Bottom line, pulling up on your pedal stroke and trying to achieve the perfect pedal stroke or circle spin scan will not increase performance.  In fact, it is more likely to see a decrease in performance by working on mechanical efficiency since the best way to achieve the perfect circular pedal stroke is to push down easier.  If you push down easier, the extensor muscles will produce a similar torque to the flexion muscles and hence produce a better mechanical efficiency but who wants to go slower.  I would rather give up mechanical efficiency and just go faster.  How about  you?

Sea Otter CX