Fit Or Fat: Nutrition and Exercise

Why Can I Run Faster Than My Super Strong Boyfriend?

Posting Date: 10/25/2000

Q: I?m a runner and my boyfriend is really into weight lifting. We?re both quite fit, but I am able to outrun him by a long shot. This makes him mad. How can he be so strong and yet do so poorly at endurance activities?

A: Good for you! I?m sure a quick ego booster for your boyfriend would come with a few minutes in the gym -- with you trying to lift the same weight that he lifts! No way, right? Remind him that you both have trained your bodies to excel in different ways.

It?s easy to see why you wouldn?t be able to lift as much as he, but it isn?t so clear going the other way. It seems that if he is so strong he would be able to run as well. Not so -- here?s why.

When weight lifters get bigger muscles they don?t increase the capillaries that feed these muscles. The muscle doesn't lose capillaries, but new ones don't grow to nourish the added bulk, so there are fewer capillaries per square inch. Additionally, muscles that have enlarged from weight lifting have proportionately fewer fat-burning enzymes. While they're great for explosive or power moves, hypertrophied, or enlarged, muscles often lack endurance. Despite their muscle mass, weight lifters have limited capacity for sustained exercise.

You may also wonder why some serious power lifters -? not your typical weight lifter, but the guys who do explosive, high-weight/low-repetition power lifting ?- tend to be a bit fat.

The type of training they do is mostly anaerobic, sugar burning, which does not burn fat. This kind of high-intensity training means that their muscles rely largely on a quick, sugar-burning system for energy. Very little of their glycogen (stored sugar in the muscles) or fat is used during such workouts. This also means that little fat is needed after their workout to replace glycogen. So, while they are incredibly good at building large muscles, they don?t burn fat very well and they tend to have more body fat.

On the other hand, the bodybuilders whose workouts involve slightly lighter weights with more repetitions and include running, cycling, or other aerobic exercise get the best of both worlds. Their workouts use more of the lactate and aerobic systems. Fat is burned only in the aerobic system, but both systems drain the muscles of glycogen, which then has to be replaced following exercise. Replacing glycogen requires burning fat.

So the bodybuilder gets the muscle enlargement and strength associated with sugar-burning sports and the oxidative enzyme growth and new capillaries associated with endurance sports. Also most body builders are quite strict about the amount of fat in their diet. Added together, these three things -- weightlifting, aerobic exercise, and careful dieting -- make for very attractive, highly muscled, low-fat bodies.

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