Ask the Coach: Dead Legs on a Century

By Coach John Hughes

Eddie writes, “Last weekend I attempted the Big Bear Century. It’s challenging with 8,700 feet of climbing in the 100 miles. Most of the climbing is in the second 50 miles – two climbs up to 8,500 ft. I live at sea level in the Los Angeles area so the altitude was also a factor. With all the climbing and the altitude I’d planned to take 8 hours or so. I’d trained well with 2,770 miles in my legs this year and I’d ridden a couple of 6-hour flattish centuries. Two weeks before the Big Bear I rode the two big climbs to familiarize myself. For the last two weeks I cut back on my miles so I’d be fresh at the start.

The first 50 miles were rolling terrain. I got into a strong group and we made good time. We stopped briefly at the rest stops but I didn’t like most of the foo. I felt strong on the first climb. After descending there were to two minor climbs and I started to fade. By the time I got to the start of the second 2,000-foot climb my legs were dead.  What happened?”

Coach Hughes responds

Your dead legs are the result of several different factors:

Training

You trained very well with plenty of miles in your legs.  As a rule of thumb you needed to do at least one long ride that takes 2/3 to 3/4 of the projected duration of the century. The lengths of the longest train rides are in hours, not miles, so you can relate a flattish century to a mountainous one. You rode a couple of six hour centuries, 3/4 of the duration of your planned Big Bear. You were smart to scout the course by riding the tough last 50 miles – this is what the pros do. You then tapered so you had good legs at the start. Your dead legs weren’t the result of your training.

Pacing

You rode the first 50 with a strong group. You stayed with them but it might have been a little fast and fatigued you. Pacing is critical: the level of effort in the first half should be about the same as the planned level of effort in the second half. In rides often the best group for you to ride with is behind you.

I wrote a column on Ask the Coach: Lessons from a Did Not Finish

Fuel

When you’re riding your burning a mix of glucose and fat. Your body has about 100,000 calories of energy stored as fat, an unlimited supply. Even the skinniest pro has enough body fat to fuel a long race. The glucose comes from glycogen, which is stored in your muscles and liver. You can store approximately 450g of glycogen (1,800 calories) although the amount varies widely based on body mass, diet, fitness, and recent exercise. Glycogen stores are limited: “During intense, intermittent exercise and throughout prolonged physical activity, muscle glycogen particles are broken down, freeing glucose molecules that muscle cells then oxidize through anaerobic and aerobic processes … The rate at which muscle glycogen is degraded depends primarily upon the intensity of physical activity; the greater the exercise intensity, the greater the rate at which muscle glycogen is degraded.” (Fundamentals of Glycogen Metabolism for Coaches and Athletes)

I wrote a column on What’s the Best Food for Cycling.

Daily diet

Because you can burn through all your glycogen stores it’s important to eat enough during the week.

In the Cyclist’s Food Guide, 2^nd ed. Nancy Clark recommend a daily caloric intake for a recreational cyclist who rides an hour or so a day and who weighs:

• 100 lbs (45 kg) — eat 200 – 300g (800 – 1,200 calories) a day
• 125 lbs (57 kg) — eat 250 – 375g (1,000 – 1,500 calories) a day
• 150 lbs (68 kg) — eat 300 – 450g (1,200 – 1,800 calories) a day
• 175 lbs (80 kg) — eat 350 – 525g (1,400 – 2,100 calories) a day

She recommends a daily caloric intake for a highly competitive cyclist with high intensity workouts and some double workouts who weighs:

• 100 lbs (45 kg) — eat 400 – 500g (1,600 – 2,000 calories) a day
• 125 lbs (57 kg) — eat 500 – 625g (2,000 – 2,500 calories) a day
• 150 lbs (68 kg) — eat 600 – 750g (2,400 – 3,000 calories) a day
• 175 lbs (80 kg) — eat 700 – 875g (2,800 – 3,500 calories) a day

For any rider about 65% of these calories should be from carbs.

Your personal caloric need is somewhere in between these recommendations depending on how much time per week you ride and how hard you ride.

Put simply at each meal cover your plate with carbs with a serving of protein the size of a deck of cards and a limited amount of oils and fats

Sources of carbs

Carbs aren’t just bread, pasta and potatoes. Fruit, veggies and unsweetened fruit or vegetable juices are great sources of carbs. Cereal, rice and legumes such as beans and lentils are also good sources of carbs. Dairy products also have some carbs. (Swiss Food Pyramid for Athletes). The pros consume copious amounts of these.

You may have read that carbs are bad for you and cause weight gain. Not true! Weight gain comes from eating too many calories from any source. Fats and oils are more of a problem because one gram of fat has nine calories while a gram of carbs has four calories and a gram of protein also has four calories.

Calorie King is a great resource for thousands of foods. For each food it tells you the total calories, calories from carbs, fat and protein and the amounts of vitamins and minerals, e.g., sodium and potassium.

High fat – low carb diet

Some riders follow a ketogenic diet (low carbs and high fat) on the theory that this improves fat metabolism and spares precious glycogen. According to a position paper on Nutrition and Athletic Performance by the American College of Sports Medicine a high fat – low carb diet doesn’t improve performance.

I wrote a column on the ketogenic diet.

Carbo-loading

To be sure your fuel tanks are full of glycogen for the century, starting three days before the ride increase the daily proportion of the carbs you eat to about 75% of total calories and cut back on the protein, fats and oils so your total caloric intake doesn’t increase. You may gain a little weight because glycogen is stored with water, which you’ll use during the ride. The morning of the century eat a breakfast primarily of carbs.

My column on Carbo-loading explains more.

Caloric burn rate while riding

If you are riding at 15 mph (24 km/h) you are burning about 4.5 calories / lb. / hour (10 calories / kg / hour). If you weigh 150 lbs, then you are burning about 675 calories / hour, about half from glucose (338 calories) and about half from fat (338 calories). You have 1,800 calories of glucose stored as glycogen so burning 338 calories of glucose per hour so you’ll run out of glucose in about 5-5:30 hours.

If you are riding at 20 mph (32 km/h) you are burning about 7.5 calories / lb. / hour (16 calories / kg / hour). If you weigh 150 lbs, then you’re burning about 1,125 calories / hour, primarily from glucose and you’ll run out of glucose in about 1:30 – 2:00 hours.

These burn rates are rough estimates if you’re riding solo on flat terrain with no wind.

The first half was hilly so you were burning more calories than the above estimates and later on the first big climb you were burning a lot of calories.  You didn’t like the food at the stops and didn’t eat enough to avoid glycogen depletion.

During the ride

American College of Sports Medicine (ACSM) recommends consuming 25 to 60 grams of carbs (1 to 2 ounces or 100 to 240 calories) per hour after the first hour of exercise. This is sufficient for several hours of exercise. If you are riding for three hours or more start eating carbs in the first hour. If you are relatively small or exercising lightly then 25 grams / hour is enough. If you are larger or riding at a moderate to fast pace eat up to 60 grams / hour.

These are calories of carbs, not total calories. A medium size banana has about 100 calories, all carbs. A chocolate chip cookie (2-1/2 inch in diameter) has 48 calories but 27 calories from carbs.

You were in a strong group and it can be hard to eat enough if you’re riding briskly. It’s also hard to consume enough on a sustained climb. Eating at altitude is particularly difficult when you’re breathing heavily and eating interferes with the breathing. At altitude it’s wise to stop briefly and eat something at least every hour.

You had dead legs because you didn’t eat enough carbs, ran out of glycogen and bonked. Next time try to find out in advance what food and drink will be at the stops. If they aren’t appealing bring some of your own. Also, carry a couple of reserve gels (100 calories of carbs in each) in case you start to bonk.

You trained very well and built up the fitness necessary to complete the century. In your future training, practice eating carbs every hour so it becomes a habit. Eat by your watch. Note what time you start to ride and every hour ask yourself if you’ve eaten enough — if not make up the deficit.

Related columns

• How to Avoid Bonking
• Nutrition for Performance
• 14 Tips for Endurance Riders
• Anti-Aging 7 Nutrition Myths

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Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written over 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.