MAF Test Revisited

Probably my most frequent ride is a MAF Test. Designed by Dr. Philip Maffetone as a diagnostic, I have been using my modification of his test not only as a diagnostic, but also as my daily training ride. The way I ride a MAF test is to ride 20 minutes at low speed from my home to the Rice Track to warm up, ride for 45 minutes on the Rice track maintaining my heart rate at just below 140 beats per minute, and then ride the 20 minutes back home to cool off. From a lot of experimentation, I have determined that, for me, on Joe Friel's scale of heart rate zones, 130 to 140 beats per minute is zone 2, the aerobic zone. MAF stands for Maximum Aerobic Fitness, the Test being the average speed I can maintain while staying within zone 2. I have posted on MAF tests on this blog many times before. I began riding MAF tests at the end of 2012 and for the first nine months, I posted an update of my MAF test results at the end of each blog post. Thereafter, I posted periodic updates and analyses of these results. I have recently made some new observations and drawn some new conclusions from my MAF Test rides and the purpose of today's post is to share these with you.

The Graph

The figure at the top of this post is a graph of every MAF test I have ridden, from when I first started riding them at the end of 2012 until a few days ago. I have been riding MAF Tests fairly regularly for going on 3 years now, and when I look at the pattern of MAF Tests scores, I see that the major pattern is that the scores go up and down, corresponding to major events in my life that interfere with my cycling. The lows seem to come every December. In the first place, December weather in Houston is particularly hostile to cycling, and in the second place, chance has decreed that some of the biggest disruptions in my life have occurred during recent Decembers. The main comfort I take from this observation is that when life keeps me from riding for a while, I can quickly regain my lost fitness.

Overlaying the daily, weekly, and monthly ups and downs in my MAF Test scores may be a long term increase in my average score, as indicated by the straight line overlaying the graph, courtesy of Microsoft Excel's best fit function. To be honest, I am far from sure that this long term increase in meaningful, but am open to the possibility that it might be. An alternative explanation is that my life has become more compatible with cycling recently, that I have been riding more regularly for the past few months, and that as a result, my fitness is at a high. Rather than getting progressively better and better, I just happen to be at a peak of fitness right now. There is no way I can think of to distinguish between these two explanations.

What Does a MAF Test Measure?

At a technical level, the answer to this question is obvious and is given above; it measures speed at a constant heart rate. But at a more pragmatic level, that is, what does a MAF test result tell me about my cycling ability, the question is much more difficult. I certainly don't know the answer for sure, but I believe it measures something proportional to how fast I can ride at the end of a "long" ride. (A long ride might be as short as 50 miles or as long as 130 miles, depending on my fitness at the time.) That is, if my MAF Test score is 16 miles per hour, I might be able to ride 14 miles per hour at the end of a 130 mile ride, but if my MAF Test score were 14 miles per hour, my speed at the end of a long ride might be 12 miles per hour.

At the level of physiology, I think it is fairly well established that the MAF Test measures cardiovascular fitness. This consists of two components, the heart, which is used by all exercise, and the blood vessels servicing my cycling muscles, which are mostly specific to cycling. It does not measure the strength of those cycling muscles, and in fact, when I am fit and ride fast MAF Tests, my leg muscles get much more tired and overtraining is much more likely than when I am less fit and ride slow MAF Tests.

Finally, at the level of health, I think my MAF Test score is a measure of that aspect of my cardiovascular fitness that the medical community is so concerned I keep up. Thus, I believe that if my MAF Test score is 16 miles per hour, I am healthier than if it is 14 miles per hour. My reason for saying this is that a MAF Test corresponds exactly to the kind of exercise the medical community recommends for cardiovascular fitness, so if I do as the medical community recommends, and if a score increases as a result (e.g. the MAF Test mph), then I think it is reasonable to suggest that the score is measuring what the medical community cares about.

Is Speed the Only Output of a MAF Test?

According to Philip Maffetone, yes. However, over the years, I have started tracking other outputs that I think give me insight as to my fitness. These are as follows:

• I use the lap timer on my Garmin cycling computer to measure the MAF Test score both for the whole 45 minutes, but also for the first, second, and final 15 minutes of the ride. On one ride, these speeds may be almost the same. On another, each 15 minute period might be slower than the previous one.
• I carefully note how I feel. Some of the things I pay attention to is how tired my legs feel, how generally tired I feel after the ride, and, during the ride, if I feel like I want to ride faster and my heart rate is holding me back, or if I am pushing a bit to keep my heart rate up near 140 beats per minute.
• Although my heart rate during a MAF Test is fixed, there are nonetheless aspects of this heart rate that vary, and which I note. In particular, I note if my heart rate is steady, and thus easy to maintain at the desired rate, or if it is jumping up and down, requiring me to make constant adjustments to keep it in the desired zone. I also note how quickly and how far my heart rate falls during the cool down ride on the way home.

What is the Best Way to Improve my MAF Test Score?

If I have taken a couple of weeks off riding and I ride a MAF Test, my score might be as low as 12 miles per hour. A common strategy I might employ under such circumstances is to ride 6 MAF Tests a week, taking one day a week as a rest day. If I do that, I can eventually get my MAF Test score up to something between 15 and 16 miles per hour, but typically cannot get over 16 miles per hour. This process takes about 6 weeks. If I continue that schedule thereafter, I will maintain that level of fitness, but not improve it.

Once I have reached the steady state described above, I have found two ways of further increasing my MAF Test score; ride intervals¹ (riding "fast") and/or ride longer rides². Both of these raise my overall score, but in different ways. Imagine that after months of riding 6 MAF Tests a week, my average MAF Test score is 15.8 mph. If I look at the 15 minutes splits, I might find that the first 15 minutes I am riding at 16 mph, the second at 15.8 mph, and the third at 15.6 mph, resulting in the observed overall average.

If I replace one of my MAF Test rides each week with an interval ride, I might find that my overall average speed increases to 16 mph. When I look at that result more closely, I will find that my speed for the first 15 minutes of the ride might be 16.2 mph, then 16 mph for the second, and 15.8 mph for the last, for an average of 16 mph.

If I replace one of my MAF Test rides each week with a long ride, my average MAF Test speed might also increase to 16 mph. However, when I look at that result more closely, I find this increase is due more to an increase in endurance than an increase in speed; when I look at the 15 minute splits, the first remains at 16 mph, but rather than falling off, the second and third 15 minutes remain at 16 mph, resulting in an overall increase in the average.

Given the different ways that intervals and long rides increase my MAF Test scores, might I get an even greater increase by adding both to my routine? As described below, I find that I risk exhaustion and overtraining if I do that. There may be training schedules that could overcome this difficulty, and I hope to try just than in the future, but have not done so to date.

Getting Tired

Everything I have read and all of my experience indicates that an optimum training protocol is governed by what I call a "Price Is Right" algorithm; train as hard as possible without going over the limit where exhaustion and overtraining occurs. Regular readers of this blog know that overtraining has been a real problem for me. After searching for an objective measure of overtraining for years, I have given up. What I am doing now is subjectively monitoring how I feel to determine when I am training too hard, and I find that is working pretty well. I find that if I attempt to ride a MAF test 7 days a week, within a couple of weeks, I will experience exhaustion. If I cut this back to 6 days a week, I can continue this schedule indefinitely, and never feel close to exhaustion. If I replace one of those 6 rides with either intervals or a long ride, I can almost maintain a six day a week schedule, but find that I am teetering on the edge of exhaustion and overtraining, and have to take an extra rest day now and then. When I have tried to ride 5 days a week, with 3 of those days being MAF Tests, one a long ride, and one intervals, I was exhausted at the end of two weeks. Could I ride both intervals and a long ride by reducing the number rides per week to 4? How about if I took 1 week out of every 3 as an easy week where I rode only MAF Tests? These are ideas that I have not had the opportunities to test, but would very much like to. Stay tuned!

Loose Ends

Besides monitoring the speed of a MAF Test, I also note my heart rate at the end of cool down, and how steady my heart rate is during the Test. What I have found is that these indicators seem to provide the same information as the MAF Test score; when my MAF Test score is high, I also find it is easier to maintain my heart rate during ride, that it is steady instead of jumping up and down, and that my heart rate falls faster and farther on the cool down ride at the end. That said, these alternative indicators are useful because the MAF Test speed is affected by external factors; it is lower when the temperature is high, when the temperature is low, or when it is windy. If my MAF Test scores are lower than I would expect, and if I am wondering if it is my training plan or the weather, if I see that my heart rate is steady and decreases nicely during cool down, then I am reassured that my training is on track.

Does it make any sense to use a MAF test as a training ride? After all, that was not Philip Maffetone's intent. To answer that question, I would have to know why I am training. One big reason is health, and for that purpose, 4 to 6 MAF test rides a week could not be a better training plan, at least according to the medical establishment. The other is to be ready for more interesting rides as they present themselves. Unfortunately, I do not currently know what interesting rides I am likely to be doing, so to answer that question, I have look backwards. To date, I have successfully completed two brevets³, one in 2012, one in 2013. I had not discovered MAF Tests in 2012 so they were not part of my preparation for that ride. By 2013, MAF Tests were the most frequent ride I did in preparation for my brevet. I was better prepared and turned in a better performance in 2013 than in 2012. Whether that was due to the MAF Tests or due to the greater experience I had acquired is impossible to know, but I do think it suggests that MAF Tests are not harmful as training rides for distance cycling.

Bottom Line

If you have made it this far into the post, you may think me a humorless, unpleasant person, riding around and around the Rice Track, monitoring my heart rate, and ignoring my friends and family. What about fun rides and riding with my wife? Not to worry, I will never pass up a fun ride for a MAF Test, and I ride with my wife whenever and wherever she likes. One of the main reasons I ride so many MAF Tests, and that I ride them on the Rice Track, is because it is on the way to my wife's work. We leave the house together in the morning, she continues on to work, and I turn off to the track to get in my daily workout. When we can manage a fun ride, we do; nothing would please me more than to have my MAF Test rides displaced by beautiful rides through the countryside. While I wait for that to happen, however, my MAF Test rides keep me healthy and fit. See you at the track!

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Footnotes

1) Examples of intervals are as follows:

• Ride from home to the Rice Track as for a MAF test. Ride 15 minutes at MAF Test speed. Then ride 6 laps as fast as I can, ride at MAF Test speed for two laps, and repeat for a total of three times. Ride, maintaining a MAF Test heart rate, to complete a total of 45 minutes on the track; typically 5 to 10 minutes. Ride home from the Rice Track as for a MAF test. 
• Ride from home to the Rice Track as for a MAF test. Ride 15 minutes at MAF Test speed. Then ride 1 lap as fast as possible, 2 laps slowly, 2 laps as fast as possible, 3 laps slowly, 3 laps as fast as possible, 3 laps slowly, 2 laps as fast as possible, 2 laps slowly, and 1 lap as fast as possible. Ride, maintaining a MAF Test heart rate, to complete a total of 45 minutes on the track; typically 5 to 10 minutes. Ride home from the Rice Track as for a MAF test. 

2) Long rides are 30 miles long or longer. I selected this number from experience, this is the minimum length of ride I have found that will increase my MAF test scores.

3) A brevet is a challenge ride where the challenge is to complete a relatively long distance in a generous but fixed amount of time. A more detailed description can be found on the United States Randonneuring website. The brevets I completed were each 200 kilometers (124 miles) long and had to be completed in 13½ hours.

Track Addict

A photograph of the Tioga Pass Road taken in 1966. This is at the beginning of the descent described below. Yes, the road we were descending was unpaved.

As a teenage cyclist, I took tremendous risks. I remember passing cars at high speed while descending some of the steeper roads in the Sierra Nevada mountains. I remember being puzzled as to why the drivers of those cars were so upset with me. However, I also remember a turning point, which happened as I descended from Tioga Pass heading towards Nevada. The road is steep, narrow, has switchbacks, and has a sharp fall-off on its southern side; if I had missed a left turn, I would have plummeted thousands of feet to my death. I thought nothing of it, I wasn't planning on missing a turn, so what was the problem? As I was hurling down this road at some very unsafe speed, weaving through the switchbacks, I heard a spoke break in my rear wheel as I banked hard through a left turn. I didn't think much of it and continued at the same breakneck speed. On the next left turn, a second spoke broke. "What can I do?" I remember thinking, "I've got to get to the bottom of the hill, and I don't want to be left behind by my friends." The turn after that, two spokes broke. I may have been stupid, but even back then, I could do math. Not only was I loosing more and more spokes, I was loosing them at a faster and faster rate. I would not be long before my back wheel collapsed, causing me to plunge to my death. So I slowed down, let my friends get ahead of me, and eventually made it to the bottom of the hill where I replaced the missing spokes, and more importantly, started riding as if I were mortal.

Of course, my memory cannot be accurate. Even back in the day of robust, 36 spoke wheels, my bike would have become unrideable with four spokes missing. So maybe I slowed down after the second spoke, or maybe even the first, but the point is the same. I learned my lesson and rode more sensibly, and that is good. Unfortunately, those who are not busy being born are busy dying. In the blink of an eye, I turned from a reckless teenager into a timid old man. Pass cars? Now I don't even want to be on the same road with them! And it gets worse when I don't challenge myself. If, for some reason, I don't ride for a few days, a ride which I previously found pleasant becomes an exercise in terror. Although there are many reasons besides safety that I ride the Rice Track, after spending so much time on that track, I find it terrifying to ride on the streets; I have become addicted to the Rice Track!

There are two problems with being a Track Addict. Firstly, and perhaps most importantly, whatever good things I can say about the Rice Track (and there are many) it certainly lacks the variety, beauty, and much of the fun of a ride on the roads (assuming I pick good roads.) Thus, by spending all my time on the track, I miss out on what many would argue is the best part of cycling. A lesser but still serious disadvantage of track addiction is that the track is not always available and this gives me one more excuse not to ride.

So, is the answer to "just say no" to riding on the Rice track? Heck, no! The Rice Track is just too useful. And besides, I can control my addiction, I promise. Last week, the Rice track was closed all week, as the space was being used for other (non-cycling) activities, and rather than not ride, I girded up my loins and rode out on the Bayou. And to be honest, it is not as if I am giving up interesting rides to ride the track. Heck, I have done the Bayou ride about as often as I have ridden on the Rice Track, and at this point, it is almost as boring. Rather, I use the Rice Track to stay in shape so that when opportunities for more interesting rides come along, I am ready for them. But still, when I get to the bike track, all prepared for a low stress ride during which I can get lost in my thoughts, find the track closed, and have to shift to riding in traffic, my feelings make the fact that I am undergoing withdrawal undeniable.

This all segues into a broader discussion within the cycling advocacy community, and a heated one at that. Vehicular Cycling refers both to a set of rules for how cyclists should behave for maximum safety when riding in traffic as well as a preference for riding in traffic as opposed to riding in bike lanes, on bike paths, or using other dedicated infrastructure; it is the latter definition that is relevant here. Advocates for vehicular cycling argue against an investment in dedicated cycling infrastructure because they feel that, ironically, they make cyclists less safe. This distinction came up in a recent discussion on the Facebook page for Houston Critical Mass.  On their last ride, a combination of the normal ride policy, questionable behavior by the Houston Police, and possible lapses by the volunteers who help with the ride, resulted in a large number of riders getting separated from the main group and finding themselves either lost or in neighborhoods where they were not comfortable. The old timers in this group tend towards an urban sensibility and snarkiness towards new riders which caused them to ridicule those who complained about having been abandoned. The suggestion was made that these "whiners" just ride on the Rice Bike Track if they were too wimpy to handle the streets.

Research seems to support the hypothesis that provision of protected bicycling infrastructure is the best way to significantly increase the number of cyclists on the road. Recently, I posted about some recommended bike routes that I felt were unsafe. That said, I would not want cyclists to be discouraged from riding with traffic. There are simply way more places to go on a bicycle than there are dedicated bike routes. But in the end, I very much appreciate dedicated cycling infrastructure when it is available, even if it is just a third of a mile oval in the middle of a parking lot. So let me take the opportunity to say "Thank you for the track, Rice University!"

Tour de Pink V

A selfie taken at our start of the 2015 Tour de Pink. The start/finish line is to the left of my head, marked by the pink and yellow decorations. There is nobody else there because we got there a bit late and everyone else had already left. This picture would have been better had we used a selfie-stick, but when I attempted to purchase one at Best Buy, I was told that I was over the legal age for purchasing this device.

This year, my wife and I rode in the Tour de Pink for the fifth year in a row. As in previous years¹, there were rides of 12, 23, 34, 47, 63, 81, and 100 miles. The routes were the same as for the previous four years and are shown on the map I posted in 2012. Because of my dad's illness and death, we were unable to train this year, so instead of our usual 63 miles, we rode the 34 mile route. I confess that it was discouraging to "go backwards", to have to decrease our mileage from previous years rather than increase it. On the other hand, because the 34 mile route goes over different roads than the 63 mile route, this change provided some much appreciated variety.

There were changes to the signup and fundraising aspects of the ride this year that I did not like. Since last year, the organizers had their website redone. Somehow, the developers who did that were not able to bring forward the membership information from the previous design so I had to re-enter all my information. Then, after I had committed to riding, I was informed that the fundraising schedule had been changed. In previous years, we had until one month after the ride to complete our fundraising. This year, I was informed, fundraising had to be completed before packets could be picked up, a few days before the ride. Honestly, I always self-fund so I really didn't care, but my wife enjoys getting some of her friends to support her ride, and this made it more difficult for her to do so. Compounding the problem, and another consequence of having had a rough year, we were signing up relatively late, not the organizers fault, but had we known about the tighter fundraising deadline, we might have pulled it together to sign up earlier. But the coup de grâce came when, in a last minute email, the organizers told us that although the deadline for fundraising was Thursday, they needed to "run the numbers" on the previous Monday, so the real deadline was not Thursday but Monday. At that point, we gave up on my wife being able to fundraise and I sat down to donate to both me and my wife. I did that the Sunday prior to the new deadline of Monday, since I had no idea what time on Monday they would "run the numbers." When I went to donate to myself, I was dismayed by the huge amount of information the organizers insisted they get from me before they would deign to take my money, but in the end, the donation was made. I then went to donate to my wife. After redundantly entering all the same information, I was told that "something had gone wrong" and that I had to "contact their fundraising department."  I would have hoped for a phone number for the fundraising department as part of this message, but it was not provided. Further, try as I may, nowhere on their website could I find any such thing as a fundraising department. I called their main number and left a message, hoping they would call me back before "running the numbers." The next day, my wife called them to resolve this issue, and they told her that this was a feature, not a bug. "The anti-fraud feature of our new website was triggered when two donations came in right after another from the same credit card." (Of course, nobody would ever want to make donations to more than one rider. Sheesh!) Next, they didn't want to take her money. "Just pay when you pick up the packet" they suggested. This didn't work for us because our team captain was picking up packets for the whole team, so when my wife insisted, they reluctantly took her credit card number. The final irony came when I went to my LBS to pick up some last minute parts and found that, coincidentally, they were the site of packet pickup. I asked the people giving out packets if our team captain had picked up our packets, and when they checked, they said he had not. "We had a very early deadline for registering teams for team pickups this year" the person behind the counter said. I am sure I am just projecting, but I could have sworn that person took perverse satisfaction in this inconvenience. When we got to the ride the following Sunday, it seemed to us that there were many fewer riders this year than previously. I wonder why (he asks sarcastically)?

So, bad year, discouraged at doing a shorter ride, annoyed at the organizers, getting up at 5 am to drive in the dark to the ride start, getting there a bit late and missing our team, this was not a good start. A few miles into the ride, we encountered an unfortunate stretch of road with a lovely wide shoulder ruined by a rumble strip. It looked like there might have been enough shoulder on the far side of the rumble strip to use, so I gave it a try. The rumble strip was brand new and especially aggressive, and riding over it caused my headlight to fall off and be ruined, and shook my cadence sensor to bits, both ruining it and preventing me from collecting stats for this ride. To top it all off, we got back to the finish early and lunch was not ready. We had the choice of sitting around and waiting for what in the past has been a mediocre lunch, or just blowing it off and going home. We chose the latter. I was all set to entitle this post "The Last Tour de Pink?" but as we were riding back to the car, my wife turned to me, graced me with her world-famous smile, and said "What a lovely ride!" All of a sudden, it was worth it. I guess we will be going back next year.

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1) We rode the Tour de Pink in 2011 before I started this blog, so that ride is described in my post for the 2013 ride. Here are the links for the rides we did in 2012, 2013, and 2014.

What Does Decoupling Mean?

This graph, taken from my Garmin cycle computer, recorded on the Rice Track, probably is recording something other than classic decoupling, except perhaps at the very end. Note the relatively constant reduction of speed at a constant heart rate over the entire time of the hour and a half ride. This is something I almost always observe, but it probably reflects something other than decoupling because it happens too soon; classic decoupling normally appears after a couple of hours of riding. The fall off in speed seems to accelerate at the very end of the ride, which might be decoupling. I do not know what the relatively constant fall off in speed vs heart rate is, but one guess is that it is due to heat. This ride, like many of my rides, starts early in the morning to avoid the heat, and the temperature rises significantly over the course of the ride.

A frustration I have reading the training literature is that it seems that nobody puts all the facts together in logical order in one place. I feel like I pick up a fact here, a fact there, and it is only months later that I can start putting all the pieces together and make sense of it. Such is the case with decoupling. A brief description of decoupling is as follows: My heart rate is normally determined by the intensity at which I exercise. If I ride my bicycle on a flat course (e.g. the Rice Track) with no wind, the faster I ride, the higher my heart rate is. If I ride at a steady speed, my heart rate stays constant, at least for a while. However, after some period of time at that steady pace, my heart rate will start to increase. This phenomenon is called decoupling. How quickly decoupling occurs is used as a measure of endurance. The longer I can ride before my heart rate increases, the more endurance I have. But, despite having read a number of well respected training manuals, it is only now, after years of research, I feel like I am beginning to get a sense of what causes it.

There a lot of indicators I can use while training to let me know if I am training at my intended level of intensity. I can monitor how I feel; if my legs feel sore or if I am breathing heavily, for example. This is sometimes referred to as Relative Perceived Exertion (RPE). I can monitor my speed using my Garmin cycle computer. Of course, the meaning of that speed is influenced by many factors: whether I are going uphill or downhill, the intensity and direction of the wind, and which bicycle I ride to name but a few. I could remove many of these variables by using the output of a power meter instead of speed to measure how much effort I am expending, but power meters cost more than I am willing to spend (in the ballpark of $1,000). And finally, I can monitor my heart rate.

Speed and heart rate are two different ways to measure the intensity of a ride. Both are affected by issues other than the intensity of the ride, so can be misleading. However, in both cases, if I stay aware of these other factors, I can allow for them and avoid being misled. Because heart rate and speed reflect somewhat different things, more information can be gathered by comparing them than by looking at either one by itself. In fact, I have used comparison of speed and heart rate many times on this blog. That is, after all, what a MAF test is. After warming up, I ride on the Rice Track which is flat and contains no traffic or stops, keeping my heart rate between 130 to 140 beats per minute, and measure my average speed over 45 minutes. If I am off the bike for two months or so, I return to a low level of fitness and that speed may be as low as 12 miles per hour. If I am at my peak fitness, that speed can be over 16 miles per hour. Another way I have used this comparison is to note not just the average speed, but how that average changes over time; is the average speed for the second half of a ride significantly slower than for the first, for example? If they are almost the same, then heart rate and speed are coupled. If they are significantly different, then heart rate and speed are decoupled. What would cause these two factors to become decoupled over the course of a ride?

Answering this question is difficult. It would seem that muscle fatigue must be involved, but much less is known about muscle fatigue than I would have expected. As recently as 2010, the our whole understanding of what limits aerobic exercise was turned upside down (European Journal of Applied Physiology (2010) Volume 109 Pages 763-770; explanation here.) I hope to return to this topic later, but for now, I suggest we consider some aspects of muscle fatigue to be an observation without explanation, it happens and we don't know why. However, one part of muscle fatigue is well understood, and that one is important; glycogen depletion. To to explain how this contributes to decoupling, I have to talk about two¹ different kinds of muscle fibers, fast twitch and slow twitch,and the fuels that they can use.

The names fast twitch and slow twitch refer to technical aspects of the electrophysiology of these different kinds of muscle fibers; it is only coincidence that fast twitch muscle fibers are used when I ride fast, and slow twitch when I ride slow. Fast twitch muscle fibers are very strong but tire quickly. They are used in a sprint, for example. Slow twitch muscle fibers are relatively weak, but can keep going for hours. They are used in a long bike ride. Both fast twitch and slow twitch muscle fibers can use glucose as a fuel. This glucose can either come from glycogen stored in the muscle fiber itself or from the blood, which mostly comes from food I eat. However, the glucose from glycogen can be provided much more quickly than glucose from blood; no matter how much I eat, I will have to slow down when my muscle glycogen is gone. In addition to glucose, slow twitch muscle fibers can use fat as fuel. (Fast twitch muscle fibers cannot use fat, they can only use glucose.) Again, this is a slower process and turns out not to be all that directly relevant to decoupling, but does have an indirect effect, discussed at the end of this post. The final, key point is that glycogen cannot be shared between muscle fibers. When fast twitch fibers run out of glycogen, they cannot borrow from slow twitch fibers, and vice versa.

It turns out that the rate of availability of different kinds of fuels is a major contributor to decoupling. If I am riding at a relatively slow pace, it will primarily be my slow twitch muscle fibers pushing the pedals. However, after a couple of hours, the glycogen in my slow twitch muscle fibers will be used up. These fibers can continue working using blood glucose or fat, but not at the same rate; fast twitch muscle fibers will have to make up the difference. The problem is, fast twitch muscle fibers are stronger but less efficient than slow twitch muscle fibers; my heart will have to beat faster to accomplish the same amount of work, resulting in decoupling.

I had always assumed that there are mechanisms for fatigue of slow twitch muscle fibers other than glycogen exhaustion, but truth be told, I do not know if there are or are not. However, if there are, they should play an almost identical role in decoupling as glycogen exhaustion. Once slow twitch muscles loose their ability to function at the same level, fast twitch fibers will be called upon to pick up the slack and their lower efficiency will result in decoupling.

The above explains "classic" decoupling, where after some period of riding, heart beat rises with no increase in effort. There are other situations where heartbeat is higher than expected for a given level of exercise. Three conditions, besides fatigue, that can cause this are emotional upset, dehydration, and heat. Heat turns out to be very important, as is the correct response to the decoupling created by heat. If one is competing in a race and attempts to maintain constant speed under conditions of high heat, one will "run out of steam" by the end of the race. Rather, one should maintain constant heart rate and allow speed to drop.

If "classic" decoupling is a measure of endurance, and endurance is something I am trying to train, what are the changes in my physiology that occur during training to improve my endurance, to delay decoupling? I'm think it is highly likely that these effects are not yet completely understood, but here are two that I think are fairly well established. First, the amount of glycogen stored in my slow twitch muscle fibers will increase. This will allow me to ride for a longer period of time before that glycogen is exhausted and decoupling begins. Second, my slow twitch muscle fibers will become "better" at using fat as a fuel. Fat will never be able to completely substitute for glycogen, but the more efficiently it can be used, the more it will slow down the use of glycogen, making it last longer.

So who cares? I do, but not because I expect any of this to improve my fitness. I care because I am curious. I like to understand why my body behaves the way it does when I ride and when I train. That said, I firmly believe that our current understanding of normal muscle physiology is woefully lacking, and that as a result, we are far from being able to design a training routine based on theoretical considerations. That is why I am such a fan of coaches like Joe Friel. I think the years of experience that the best coaches have provide a much better basis for designing a training program than the kinds of theoretical understandings discussed in this post. Finally, I think for the kind of cycling I want to do and the goals that I have, training is not all that complicated; "just ride" is probably pretty good advice. Still, trying to figure this stuff out, while not all that useful, I find to be a great deal of fun.

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1) There are more than two kinds of muscle fibers, there are at least three, but my simplified explanation is adequate for this post.

Bike Lame

Clearly, this is social commentary, but what is it saying? That bikes are lame, they shouldn't be on this road? That bike lanes are lame? That the absence of a bike lane on this road is lame? Who knows? This photo was taken just outside of the town of Point Reyes Station in California.

There is a heated debate within the cycling community about the best infrastructure to support cycling. Some argue for the construction of bike lanes and bike paths, so that we can have a protected space where we can ride without having to contend with automobiles. Others within our community feel this is a tragic mistake; that bike lanes and bike paths actually make us less safe, that we should ride in the same lanes as motor vehicles. What most of us agree on is that where bike lanes do not exist (e.g. most places), bicycles should be free to use the same roads as motorists, and that motorists should behave in ways that are safe and courteous. For example, most of us bemoan the passion with which many motorists feel that they need to immediately pass every cyclist they see; we wish they would show a little patience and to wait to pass until safe. That said, most of us cyclists are also motorists, and thus have the opportunity to see things from the other person's perspective. Thus was our recent experience when vacationing in Point Reyes, California.

Point Reyes is just north of San Francisco and Silicon Valley, and what makes it so attractive is that in stark contrast to the teeming megapolis to the south, the Point Reyes area is very quiet and rural. To that end, it would make no sense to shatter it with high speed freeways, and thus the major freeway in the area, Highway 101, lies well to the east. What that means is that Point Reyes can only be accessed via narrow, winding, country roads. Point Reyes is a major tourist destination, encouraged in part by the location therein of Point Reyes National Seashore (a real treat!) On the one hand, it would be a shame if folks did not appreciate and use this beautiful recreation opportunity. On the other, the success of Point Reyes as a tourist destination means that these narrow, winding country roads are heavy with traffic; automobiles, of course, but a plethora of bicycles as well. Because of the circumstances of this visit, I traversed these roads by automobile only. And as much as I wanted to celebrate my fellow cyclists without reservation, I found myself in what seemed to be an insoluble dilemma. It goes like this:

The speed limit on many of these roads is 55 mph. Due to the hilly terrain, the roads go up and down as well as wind around the hills, and as a result, there is no legal place to pass; there are double yellow lines for mile after mile. Many of the roads have no shoulders whatsoever. And, as noted above, they are heavily travelled. So what happened when I encountered a cyclist? In theory, I should slow to the speed of the cyclist and follow them thereafter, for as many miles as necessary. If I had done that, I would have been the only driver to do so and would have, in my opinion, created a very dangerous situation. So, in practice, I did what everyone else did, the cyclists being full participants in this illegal and unsafe ballet. The cyclist would cringe as far to the right on the narrow road as possible. I would slow down as much as possible. I would pass, leaving as much room for the cyclist as I could while trying to cross over the double yellow line as little as possible. Although passing is unsafe and illegal everywhere as indicated by the double yellow lines, I would try to pass at the least unsafe place I could find. Having done all that, I probably passed closer to the cyclist than the law allows and I certainly crossed over the double yellow line in violation of the law. Post all the caustic comments you like, I am 100% convinced I had no other realistic choice, and certainly this is the community standard for these roads, agreed-upon by both the cyclists and the drivers.

Am I saying that cyclists do not belong on these roads? Absolutely not! And even if I did, I would be in conflict with the State of California which posts "share the road" signs on these roads, along with numbered bike route signs. I believe that some of the roads to which I refer are part of Adventure Cycling's routes, and this I find very discouraging. I have a long term dream of taking a tour of the United States using the Adventure Cycling routes, and now having seen what roads these routes use, I would be unwilling to ride on them. What I am saying is that all of us, the State of California, Adventure Cycling, the cyclists, the drivers, need to admit that we have created an impossible situation, and to develop and implement a realistic solution. Of course, this is not just a problem in California. I have cycled on roads here in Texas that have many of the same problems.

So what is the solution? It would be arrogant to think I had the answer, but I do have some thoughts. Being the scientist I am, my first reaction is always to gather more facts. Implicit in everything I have said so far is the assumption that it is dangerous to put bicycles moving at 10 to 20 mph in the same lane with automobiles moving at 55 mph, but is that true? My son, the Google data scientist, was with me on this trip and cited a study showing that when the speed limit on freeways was set too low, the mixture of drivers who drove at a faster but still safe speed with those drivers who felt compelled to follow the speed limit created more accidents than if the speed limit were raised so that everyone drove at the same, fast speed. When I looked into these studies, they were less than ideal. In addition, what may be true for motor vehicles moving at mixed speeds may or may not apply to a mixture of fast motor vehicles and slow bicycles; unbiased, well designed studies are needed, and they need to be extended to study what happens when bicycles and motor vehicles mix. Many related questions can be asked. To what extent does the risk of mixing slow bicycles and fast cars depend on the level of traffic? To what extent is risk reduced by a wide shoulder/bicycle lane? On roads where passing is dangerous, how effective would periodic pullouts be where slow traffic such as bicycles could temporarily pull out of traffic to allow faster vehicles to pass? What would be the optimum spacing of such pullouts? The cost of various options would have to be considered as well.

I follow Houston Critical Mass on Facebook, and there are voices there who believe the answer is to lower the speed limit. To be effective on the roads I am describing, I suspect that the speed limit would have to be lowered from the current 55 mph to something like 25 mph. Thinking about the situation around Point Reyes, this would certainly cause considerable consternation among the locals who have lived and worked in this area their whole lives and whose ability to function would be significantly degraded. But that aside, if this were to work, strict enforcemen would be essential or the new speed limits would be ignored. In anticipation of hard facts, my preferred solution is wide, paved shoulders. Whether these are shoulders or bike lines is to a large extent a matter of signage. Certainly motor vehicles should not drive on these shoulders, they should be reserved for emergencies (e.g. breakdowns) and for unpowered, slower vehicles such as bicycles. My intuition tells me that this would increase safety not only by providing a safe way for motor vehicles to pass bicycles but also providing a way to get broken down vehicles out of the traffic lane. What I do know for certain is that the status quo is unacceptable. What do you think?

Addendum: A few days after I posted this, my son and daughter in law posted about their experiences bicycling in China. One post in particular put the post above into perspective. Everything is relative; as dangerous as I found some of the roads in California, they are safety personified compared to what my son and daughter in law experienced in China.

Good Bye, Dad

Me, receiving the flag that had been covering Dad's casket, from one of the representatives of the United States Navy who honored Dad by participating in his funeral.

A recurring theme of this blog is that life is complicated and sometimes difficult, and that it often gets in the way of cycling. Over the last few years, I have spend a considerable amount of time in California taking care of my parents. Mom died before my first blog post, so her care did not receive much mention here. In contrast, visits to Dad were frequently mentioned¹. Sadly, I will never have the privilege of mentioning them again, because Dad died a few weeks ago. We had a lovely funeral service for him, beginning with a military burial at the Sacramento National Cemetery followed by a luncheon where we all shared stories about Dad. One of my stories concerned cycling, and I thought it would be appropriate to share it here.

How Dad Taught Me to Be a Bicycle Racer

My Dad was a gifted athlete. Despite being somewhat short, he was a highly successful basketball player in high school, in college, and in The Navy. That being the case, I always worried that it might have made him sad to have had as a son one of the most untalented athletes on the planet. Eventually, I did find my sport, bicycling, and even got to be rather good at it, but even that began somewhat inauspiciously.

The story starts when I was in elementary school. Most kids, when they get their first bike, ride for a few weeks with training wheels, not really using them, and quickly thereafter, head off down the road on two wheels. Not me. I wore out my training wheels, and when Dad finally had no choice but to take them off, all I could do with my bike was fall over. Dad's solution to that was to start me out at the beginning of our driveway, and to use a piece of chalk to mark the spot where I fell over. Thereafter, my goal became to get past that spot before falling over again, at which point, Dad would move the line and I would now attempt the surpass the new, harder goal. Despite the lack of promise this evidenced, Dad kept at it and eventually taught me to ride a bike.

Fast forward a few years to High School, and I had taken up bicycle racing. Despite the fact that this is perhaps the most boring sport on the planet to watch, Dad was an enthusiastic participant, driving me and the other members of The Modesto Roadmen all over Northern California to race. I remember him telling me "Never play by the other guy's rules." I had no idea what he was talking about at the time, but I now realize that bicycle racing is highly strategic and that the winner of a race is often the guy who makes the other riders ride his race.

If you know anything about bicycle racing, you know that falling off your bike is a big part of it. I remember one race where I was involved in a particularly nasty crash near the finish. Back in those days, we didn't wear the hard, plastic helmets of today, but thin strips of lightly padded leather, so I was pretty shook up and disoriented by the crash. By the time we got home, I had recovered and was able to tell Mom all about it. I regaled her with tales of abrasions and lacerations and finished with "...but after all that, I still would have been able to finish if some fat old man hadn't pulled me off the course!" At this point, Dad cleared his throat and said, with remarkable calm, "I pulled you off the course, David." He had been protecting me from being struck by the riders behind. Dad was not old then, though he eventually got old, and unlike me, Dad never got fat. However, he also never gave a thought to the unpromising material he had to work with, but gave of himself without reserve so that I might develop the love of a sport which I am still enjoying today, sixty years later.

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Footnotes:

1) Posts mentioning trips to California to care for Dad:

• Sep 27, 2014: Hanging It Up
• Jan 13, 2015: Faster, Higher, Stronger
• Mar 23, 2015: To BART and Back
• Jun 17, 2015: Training or Exercise?

The Billion Kilowatt Dam

Hoover Dam, an hydroelectric dam with a capacity of two billion kilowatts. Picture courtesy Wikipedia.

"High Hopes" is a song first popularized by Frank Sinatra, now a staple of childrens' television, that preaches the power of positive thinking. In the narrative of this song, a ram decides to knock down a hydroelectric dam roughly the size of Hoover Dam. Because he has "high hopes", he succeeds despite the apparent impossibility of the task; in the words of the song, "there goes a billion kilowatt dam." Being the dour and humorless person that I am, my thoughts immediately jump to an astonished and terrified ram in the spit second before he is crushed by the concrete fragments of the ruptured dam, the young children playing downstream from the dam, looking up to see the wall of water about to crush their fragile bodies into lifelessness, and the many lives that would certainly be lost as a consequence of the loss of a billion kilowatts of power from the power grid. I see the ram not as a hero, but as a terrorist.

But perhaps it is I, not the ram, who is the villain of this post. There is exactly zero chance that a ram could contribute to, much less cause, the failure of Hoover Dam; the young children in this post are at no risk from the ram.  On the other hand, they is at real risk of having me ruin a perfectly nice and life-affirming song for them. So what's my problem? It's not that I don't believe that positive thinking is a good thing. As a card carrying member of the medical research community, I am appropriately skeptical and ask for the same carefully controlled clinical trials documenting the power of positive thinking as I would for any prescription. That said, the evidence that people with a positive attitude are healthier than those who have a negative attitude has been pretty convincingly demonstrated. No less an authority than the Mayo Clinic has very specific recommendations for attempting to cultivate a positive mental attitude. Given that, does it make sense for the ram to have a positive attitude ("high hopes") and just go at the dam? And what does any of this have to do with cycling?

Where the life of the fictitious ram and my bicycling intersect is in the confusion I have had about what was realistic for me to accomplish in cycling. When I was in my cycling prime, back in the 1960s, I was not bad as a bicycle racer, but I was nothing special. I had fun, stayed with the pack in a lot of races, occasionally surprised the leaders by winning an intermediate sprint, but never became one of those leaders. I confess I was not all that diligent, however, so I don't really know what my potential was back then. Forty years later was a different story. I read books on training, followed them carefully, and prepared for a career as a randonneur¹, but it was not to be. I found I was capable of one 200K brevet a year, but that was about my limit. It wasn't just my age that was holding be back, there are plenty of randonneurs in their 60s and even there 70s. It may not even have anything to do with age; is actually possible that had I attempted randonneuring in my prime I would have discovered the same limitations. What is clearly true is that when I followed training plans that allowed others to complete a 200K, 300K, 400k, 600K brevet series and then complete a 1200K grand randonnée, I would find myself exhausted after the first ride. Can I prove that I could not have done more if I had tried harder? Of course not, that is not the kind of thing that can be proven, practically speaking anyway. Do I believe it with all my heart? I do.

So what is my point? My point is, might it be possible, and if so, might it be useful and/or fun to include in training plans indicators as to what the highest level of performance you can expect in that sport, the facets of that sport in which you might be most successful, and what other sports you might want to try? Not surprisingly, I believe that such indicators are possible, useful, and fun. In fact, I feel like Joe Friel's "Cyclist's Training Bible" has most of the pieces needed to do just that, they only need to be connected. I will discuss the science and practicalities of such indicators in future posts, I wish to reserve this post for a discussion of their desirability.

So, the bottom line is, supposing I am as brevet-challenged as I claim I am. Would I be better off knowing that, and living within my limitations, or would I be better off being like the dam-hating ram, trying and failing to be the brevet rider I never can be, over and over and over again? My gut tells me the former: "And ye shall know the truth, and the truth shall make you free." What do you think?

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1) Randonnering is a kind of cycling where completing a distance within a fixed period of time is the challenge. This ranges from completing 200 kilometers (124 miles) in 13.5 miles to completing 1200 kilometers (about 750 miles) in 90 hours, just under 4 days.