As I was riding the Coast last week I had plenty of time to myself, to think. I was riding sweep for a group of 28 cyclists, 495 miles down the CA coast from SF to Santa Monica.  In past years I used this ride for many different approaches to my training.  Last year it was my last prep aerobically for my 100 mile running race 12 days later – less pounding on the legs, but still 8 hrs a day of time in a HR zone.  Other years I have used it to go from out-of-shape cycling to in-shape cycling – BAM – in a matter of a week!  And, of course, there are the years where I have been fit and hammer with the front groups….key words being “already fit”…so I had my base miles in me.  After 17 years of riding a January Coast Ride, I figured it out pretty well on how it works best for me, and, I’d like to say for my athletes.  And, it keeps coming back to the same concepts…you can’t escape the base miles…

This year I finally made the decision to depart a day ahead of a bigger Coast Ride group that comes together every year.  That ride has gone from what the original Coast Ride was back in the early 90s to a mini race down the Coast.  Roadies and weekend warriors putting their fitness on the line to thump their chest that they had a solid Coast Ride….in January…!   Originally a bunch of very accomplished pro and elite triathletes started this in order to force themselves into 600 miles of easy aerobic riding back to San Diego.  It was on the Monday after SuperBowl Sunday every year, and since the 49ers seemed to be in it a lot back then, San Francisco was a fun place to be.  Besides many injuries, broken collar bones and road rash, the faster Coast Ride accomplishes very little other than going deeply anaerobic repeatedly for a couple of hours every day for 3 days (they only go to Santa Barbara, 370 miles).  That’s great when I’m preparing to race. In the winter, however, my training purpose is not race fitness; it’s base fitness. You don’t establish base fitness by going deeply anaerobic repeatedly for a couple of hours.

My notion of a base ride is a long, steady workout with heart rate mostly in zone 2. This is roughly a well-conditioned athlete’s aerobic threshold. Riding two or more hours at this effort challenges the body to make some improvements. One is to become better at using fat for fuel while sparing muscle glycogen stores. The longer your races are, the more important this shift is. The other critical shift has to do with increasing the capillary bed in the working muscles. The more capillaries you have the easier it is to get fuel and oxygen to the muscle. There are other benefits also, but for now we’ll focus on these.

The problem with this base workout is that it seems too easy at first so the athlete is tempted to abandon zone 2 and start riding variably paced with hard and easy efforts – fartlek intervals, essentially. And by so doing reduces the aerobic benefits of the day’s workout.

The aerobic threshold ride is sort of like Chinese water torture. What at first seems easily manageable eventually becomes challenging. One has to have the patience to hang in there to see what I mean. (This is one of the numerous reasons why I so often say that patience is necessary to be a good endurance athlete.) Ride for three, four, five, six hours at this effort and you soon learn what the aerobic system is all about.

Doing such a workout with a group presents problems, however. The greatest is that not everyone’s Zone 2 HR produces the same power or speed. The highly fit, usually young riders are talking easily while riding in zone 2 – as they should be. The slower, usually older riders who try to keep up are often well out of zone 2 but determined to hang on. While this workout is best done alone, if in a group the best option is for the group to split up into smaller groups of like ability – which I noticed many did during the Coast Ride – but not well enough I suspect…

The best way to do this ride is to have a power meter onboard in addition to your heart rate monitor. While in the base period I like to have athletes use their heart rate monitors to set the effort, what happens to power is the real story. The best way to explain this is to use graphics.

Example 1: 1% decoupling	Example 2: 11% decoupling

Here you see two examples (double click for a larger view) of riders doing a steady, multi-hour, zone-2 ride. In both cases they are doing an excellent job of maintaining a steady heart rate as evidenced by the red line staying almost flat on both charts. But notice what happens to power (black line). In example 1 power closely parallels heart rate. That’s good. It says that the rider is staying “strong” throughout the ride. There is no fading of power (or slowing down, if you will, even though that’s not a very precise way to measure output on a bike). I call this separation of heart rate and power ‘decoupling.’ In fact, the graph shows us that in example 1 there was only 1% of decoupling. In other words, power declined only 1% over the course of two hours of riding.

For the rider in example 2, however, the decoupling is 11%. He is fading significantly as the ride progresses. From these two examples I can tell you unequivocally that rider #1 is in much better aerobic condition than rider #2. If all they had were heart rate monitors we wouldn’t know this. Heart rate is only effective when we can compare it with something else. By itself it tells us nothing about aerobic fitness.

So does this mean that if you don’t have a power meter you shouldn’t do this workout? No, not at all. It’s still beneficial to your aerobic system. You just can’t measure your progress or know for certain when you’ve achieved good aerobic fitness. What you can do is maintain a steady HR on a familiar loop, and watch how your avg speed drops off later in the ride (decoupling) vs. past rides where you might have been fitter – or monitor for future rides on this loop that at same constant low HR you are holding on to your avg speed better, late in the ride.  What you can always do in this case is to pay close attention to how you feel. If in good aerobic condition you should be able to finish the ride strongly, albeit tired. If you’re totally wiped after four hours and are struggling just to limp home although heart rate remains in the 2 zone, your aerobic fitness probably needs a lot of work.