Tag Archives: cycling

Cycling Nutrition: The Basics – Glucose, Glycogen and Carbohydrates

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More information about the basics of fueling the muscles and hydration can be found in Nutrition for Cyclists: Eating and Drinking Before, During and After the Ride which can be purchased on Amazon.com.  For information about the book and how it relates to what I’ve posted to Tuned In To Cycling, please check out this post.

While proper nutrition is one of the most important factors affecting long-distance cycling on a day-in, day-out basis, there is so much misinformation out there that knowing what to eat and when to eat it can be Burning glucosedifficult.  Part of the reason for this is that it’s early days yet for nutrition science; much remains to be learned and nutritional theories are often revised as new information becomes available.  Another reason is that the subject of sports nutrition is confused in the minds of many with the subject of dieting.  Unfortunately, dieting in the US is a multimillion dollar industry that is fat with fads and outright foolishness.  Finally, many cyclists seem to have a deep emotional commitment to their cycling-related eating habits and resist change.  In these Cycling Nutrition posts I’ll try to present nutritional information that is based on research found in peer-reviewed scientific journals on nutrition and cycling and endurance sports in general.  In this post we look at the basics of how muscles are fueled that underlie every discussion of nutrition for cyclists. In other posts we examine eating during a ride, eating after the ride, and bonking.

Muscles burn glucose for energy.  The longer you ride or the faster you ride, the more glucose your muscles need for fuel.  When you get on the bike and start pedaling, the demand for glucose for your leg muscles increases and a signal goes out to the body to start supplying the glucose you need.

Glycogen and glucose

Where does the glucose come from?  The body doesn’t store raw glucose.  Instead, it makes glucose from other substances.  Glucose can be derived from breaking down stored fat and protein.  Subcutaneous fat (the excess fat stored under the skin) is an especially good energy source because fat contains roughly twice the number of calories as either protein or carbohydrate.  This means you get more fuel in the form of blood glucose from breaking down a gram of fat than from a gram of either protein or carbohydrate.  Indeed, breaking down stored fat to increase the level of blood glucose is the reason why exercise leads to weight loss.  The problem with relying on breaking down fat to produce glucose is that the process is relatively slow and energy intensive.  Metabolizing (breaking down) fat can be a useful long term source of energy but it is too slow and inefficient to support immediate and short term demands for glucose to fuel ongoing athletic activity.

In order to have fast access to glucose when needed, excess glucose in the blood is stored in a form known as glycogen.  Glycogen can be quickly broken down to supply glucose as needed.  The main storage locations for glycogen in the body are the muscles and the liver.  Liver glycogen is volatile in the sense that it doesn’t last long.  This is because liver glycogen serves as an energy source for the entire body.  When liver glycogen is metabolized the glucose that is produced enters the blood stream and can be used any place in the body where it’s needed.  If you go to bed with with liver glycogen stored at maximum capacity, a large proportion of it will be gone when when you wake up because it was used to fuel the body’s needs while you slept.

Muscle glycogen is more stable in the sense that once stored it remains in place much longer.  This is because muscle glycogen does not enter the bloodstream.  The glycogen stored in an individual muscle can only provide glucose for that muscle.

So, you’re pedaling along burning glucose derived from glycogen stored in your liver and your cycling muscles and everything’s just peachy.  Until you run out of stored glycogen.  The body can store enough glycogen to support approximately 90 minutes of moderate intensity exercise.  What happens when that glycogen is used up?  Where do your muscles get the glucose they need to keep working?  Some of it can come from fat that has been slowly breaking down while you’ve been riding but that won’t be enough to supply your needs.  Once you’ve exhausted your glycogen stores, most of the glucose you need is going to come from what you’ve been eating and drinking during the ride.  This is where carbohydrates enter the picture.

Basic nutrition for any endurance sport such as cycling is primarily about carbohydrates for the simple reason that carbs can be broken down to supply glucose much more quickly and efficiently than either fats or proteans.  While you’re on the bike you need a steady supply of carbs to both fuel ongoing activity and stretch the time before your stored glycogen is completely exhausted.  When you’re off the bike you need carbs to replace the glycogen you burned during the ride you just finished.  For anyone engaged in an athletic activity that lasts for 90 minutes or more, carbs are what basic nutrition is all about.

 

 

Cycling with Cars: Riding the Line

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Many new cyclists or cyclists who are thinking about using their bike to commute to work are anxious about riding in the road with traffic.  It’s not as scary as it looks and in many circumstances riding with Cycling in traffic - picture from labreform.orgcars is actually safer than riding in segregated bicycle lanes or what are euphimistically called “bicycle paths”.  If you’re going to be at all serious about road cycling or are going to commute to work you are going to have to share the road with cars.  How to ride a bike in traffic can be a controversial topic that generates discussions informed by passionately held ideologies and beliefs.  The advice and opinions expressed here are based on many years and tens of thousands of miles spent sharing the road with cars.  I ride with cars every day and I don’t want to be killed, maimed or seriously injured on the bike.  These are some of the ways I’ve found to most effectively accomplish those things.  Keep in mind that there are no hard and fast rules about riding in traffic.  You have to evaluate and adapt to each situation separately.  Riding safely with cars involves riding the line and riding defensively among other things.

The first question you have to ask if you’re going to ride in the road with cars is where in the road you should ride.  People who are not used to riding with traffic are likely to say, “as far away from the traffic as I can get.”  That seems like it makes sense but in most cases it’s exactly the wrong thing to do.  Why is that?  One of the most important things to keep in mind when sharing the road with cars, maybe the most important thing, is that it is absolutely essential that the drivers of the cars see you and be aware of you.  This seems so obvious that you might wonder why it needs to be mentioned at all.  The reason is that drivers generally aren’t looking for cyclists, they’re looking for other cars, and it’s very easy not to be aware of something that’s right in front of you when you’re looking for something else.  To see a terrific example of what I’m talking about, check out this video.  It’s only about a minute long and it’s very cool. . . . .  See what I mean?  You’re already wearing that bright and garish jersey to make yourself more visible to the drivers, you also need to ride where they have a better chance of both seeing you and being aware of you.

Riding the line

So where should you ride?  On the outer (right hand) edge of the driving lane, not on the outer edge of the road near the curb.  Many roads have a solid white line that separates the roadway from the shoulder.  You should ride as close to that white line as you can.  Depending on road conditions and the width of the shoulder, you can ride on either the roadway side of the line with the cars or the shoulder side of the line but you should try to stay close to the line.  It’s also a good idea not to get in the habit of riding directly on the line.  Road markings are usually made using a plastic or epoxy based paint and they get slippery when wet.  You’re more likely to have your wheels suddenly go out from under you on a wet road when you’re riding over the painted lines on the road.  If you get in the habit of riding directly on the painted line in dry conditions, you’re likely to unthinkingly ride on the painted line when the road is wet as well.  Practice riding to either side of the line.

Road debris - picture from humantransport.orgOn a road with a paved shoulder of even a few feet, the closer you ride to the outside edge of the roadway, the further you move away from the area of the road the driver is watching.  The drivers may be able to see you but they will be less likely to be aware of you.  In addition, the closer you get to the edge of the roadway the more likely you are to run into road debris like stones, rocks, gravel, sand, sticks, glass, garbage, bits and pieces of metal and other junk that has been swept to the side of the road by rain and passing cars.  Riding through this stuff is dangerous and you want to avoid it whenever possible. 

Unless a road is extremely narrow, traffic lanes are usually wide enough for a car to comfortably pass you when you are riding on the road side of the line.  On roads with virtually no paved shoulder like the one in Road with no shoulderthe picture at the left, you have no choice but to ride on the road side of the line.  However, even this country road is wide enough that passing shouldn’t be a problem.  If there is no line at the side of the road, ride near the outer edge of the roadway but not so close to the edge that you’re having to weave in and out of the traffic lane in order to avoid road debris.

When you’re riding down a street that has an occasional car parked along the side you want to avoid the temptation to weave out to pass the car and then drop back in toward the curb once the parked car is behind you.  When you drop in toward the curb the parked car is blocking you from the field of view of drivers who are behind you.  If there are several parked cars spaced at intervals along the side of the road, a rider who weaves in and out to pass the cars is popping in and out of the driver’s field of vision and this can be very dangerous for the cyclist.  The solution is to ride far enough into the road to pass the parked cars and stay there.  When approaching a parked car, try and see if there is someone sitting in the car who might open a driver’s side door and hit you as you go by.  People rarely look for cyclists when they’re getting out of their car and this type of collision happens more often than you might think.

Riding near the line is only part of what you can do to maximize your safety when sharing the road with cars. How you ride the line is also important.  You want to ride a smooth, steady line without weaving back and forth.  There are several reasons for this.  If you’re weaving around you may be pulling out of the driver’s zone of awareness when you go one way and into the line of traffic when you go the other.  Another benefit of riding a smooth, straight line is that it gives the driver coming up behind you confidence that you know what you’re doing so that they can reliably predict where you’re going to be when they pass you.  Think about what’s it’s like when you’re driving and come up behind a cyclist.  If the bike rider is wobbling all over the place, passing them can be a nerve-wracking experience.  If they’re riding straight and sure, passing is usually no problem.

Holding to a straight, sure line when you ride is a valuable skill for the road cyclist to have for many reasons and one of the best ways to practice this skill is by riding the line along the side of the road.  Part of this skill involves learning to turn and look back over your shoulder to see what’s behind you without straying from your straight line.  When you turn to look over your shoulder, there’s a tendency to drift in the direction you’re looking which means drifting into the line of traffic.  You can practice line riding skills like looking over your shoulder when you’re riding the line and there’s no traffic behind you.

Remember that the drivers don’t want to hit you almost as much as you don’t want to be hit.  You can make their job easier and increase your level of safety by riding the line in a straight, smooth and sure fashion.