The Marine Corps 3X Fitness Program for Men and

"Of all the military services, the Marines are the fittest and trimmest," Martin Cohen says. The U.S. Marines are "probably the best-conditioned men and women in the world."

While it may be true that virtually all of the few good men and women who make up the Marine Corps are lean and strong, they weren't born that way. They worked their way into shape and continue to work to maintain strong, slender bodies. "The Marine Corps 3X Fitness Program" tells how to emulate the Marines and turn yourself into a lean, mean fighting machine -- well, at least a lean, strong machine.

You might expect this book to be the written equivalent of a drill instructor in boot camp, yelling, screaming and intimidating you to work, work, work. But Cohen's book is nothing of the sort. His style is direct, but very well reasoned.

With minor exceptions the program Cohen lays out in this short book is a standard, no-frills exercise routine. It's made up of the three components needed for total fitness: stretching for flexibility, calisthenics for strength building and aerobics for cardiovascular conditioning.

The basic program consists of three one-hour workouts per week. Each workout contains a five-minute stretching warmup followed by 15 minutes of calisthenics, 35 minutes of aerobic acitivity and five minutes of cooling down stretches. It's all designed to be done in and around your home with little or no equipment.

All of this is pretty standard stuff. But there are a few unique and helpful ideas here that make the book particularly useful to those starting out on exercise programs.

First of all, the book basically is aimed at beginners. If you can run 10 kilometers in 50 minutes or bench press 225 pounds, this book is not for you. But if you want to lose weight and get stronger and don't know where to start, this book may be the ticket.

The most helpful information for the budding regular exerciser is contained in the sections where Cohen explains how to assess your fitness level. Once you figure out where to begin, the book takes you step by step up the calisthenics and aerobics ladders.

The program includes only four calisthenics: situps, pushups, pullups and tricep dips. But those four are enough to build strength in all the major muscle groups from the waist up. Leg strength is gained through aerobic exercises.

Marines believe in running. So the aerobics component of the routine is heavily weighted toward getting a running program going. Cohen pays lip service to other aerobic exercises -- running in place, jumping rope, cycling and swimming. But running is the clearly preferred aerobic exercise. Incidentally, for no discernible reason Cohen does not use the word "aerobic" to describe these cardiovascular conditioning exercises. Running, swimming, et al are called "cardiorespiratory workouts."

As is the case with the calisthenics, the running program is a sensible one. It pays close attention to the cardinal rule of all aerobic exercises: start slowly and increase gradually. The running program also has different levels, beginning with walking and ending up with a running pace that enables you to cover three miles in 28 to 30 minutes. The one major difference between the running program and the aerobic workout recommended in most exercise books is that Cohen recommends a minimum of 30 minutes. Most exercise authorities say a minimum of 20 minutes of aerobic activity three times a week will bring increased cardiovascular benefits.

Evidently, the Marines do not believe in taking your pulse to determine if you are pushing yourself enough to gain aerobic benefit. Most exercise physiologists today go along with Dr. Kenneth Cooper's aerobics theory: in order to get aerobic benefit you have to get your heart beating between 70 and 85 percent of its maximal attainable rate. This is called the target zone. Anything lower does not stimulate the heart enough. Anything higher and you risk putting too much stress on the heart.

Most exercise experts say that the best way to determine if you're in your target zone is to take your pulse while exercising. Maximum heart rates are determined by age. To figure out yours, subtract your age from 220. Your target zone is 70 to 85 percent of that figure. A 40-year-old, for example, has a target zone of 128-155 heart beats per minute.

Cohen says that most Marines don't use pulse readings. To judge if you're working too hard, Cohen's advice is that if you feel "lightheaded or exhausted, immediately reduce your pace until your breathing and heartbeat return to a normal level." If you don't feel exhausted, he says, the best way to judge if you're on track aerobically is to work toward the point where you are able "to sustain vigorous cardiorespiratory workouts for 30 or more minutes."

Cohen ends this book with two helpful guidelines for exericing. One is the Marine Physical Fitness Test. This simple, three-part test allows you to see how you stack up against Marine qualifications. It's also a good measurement of overall fitness. And it can help you judge your progress once you've begun an exercise routine. Few things provide more incentive to continue working out than seeing concrete improvements.

The Marine PT Test consists of doing as many situps as you can in two minutes (one minute for women). Men then do as many pull ups as the can with no time limit, and women time themselves in a flex-arm hang. The final component is the three-mile run for men and the a 1.5 mile run for women.

Finally, there are instructions for measuring your body fat percentage -- a better indicator of fitness than absolute weight. There are more accurate ways to measure body fat, but the tape measurements Cohen presents seem to be accurate. As is the case with keeping track of your PT scores, knowing your percentage of body fat can be a good incentive to keep exercising. Once those pounds of fat begin melting away, you'll want to stick to the exercises that helped get you to that point.