Walking is an excellent exercise, but it is not a complete exercise program. People who get their only exercise from walking can become stiff and inflexible, with short, tight muscles in their backs and the backs of their legs. They also may lack muscle tone and strength in their upper bodies - conditions that can lead to poor posture and chronic low back pain.

The President's Council on Physical Fitness and Sports recommends the following exercises before walking:

• Stretch: Stand facing a wall, arms' length away. Lean forward and place your palms flat against the wall slightly below shoulder height. Keep your back straight, heels firmly on the floor, and slowly bend your elbows until your forehead touches the wall. Tuck your hips toward the wall and hold the position for 20 seconds. Repeat with your knees slightly flexed.

• Reach and Bend: Stand with your feet apart and arms extended over your head. Reach as high as you can while keeping your heels in the floor, and hold for a count of 10. Flex your knees slightly and bend slowly at the waist, touching the floor between your feet. Hold for 10 counts. Repeat 2 - 5 times.

• Knee Pull: Lie flat on your back with your legs extended and your arms at your sides. Lock your arms around your legs just below the knees and pull your knees to your chest, raising your buttocks slightly off the floor. Hold for 10 - 15 counts. Repeat 3 - 5 times.

These exercises are designed to increase flexibility and strength and to serve as a warm-up for walking.