When you put demands on bone, it responds by becoming stronger and denser. Any activity that works against gravity, including walking and climbing stairs, stimulates the growth of new bone tissue. Here are six bone-building exercises from Johns Hopkins.

Exercise and adequate calcium are two of the three essentials for preventing osteoporosis. Vitamin D is the third. Regular exercise can help limit bone loss, improve your balance and coordination, and strengthen the leg and torso muscles that help you stand upright. Calcium within bones makes them strong, and taking daily calcium supplements can ensure that your bones will remain strong.

Here are six weight-bearing and resistance exercises you can try to help prevent bone loss. You would achieve the best bone-building results by doing this regimen with exercise machines. However, you can do a similar workout at home using dumbbells and resistance bands (such as Theraband or Dynaband).

For starters, do one set of six to eight repetitions of each exercise and build up to doing two sets. Once you can easily do two sets of six to eight repetitions, increase the weight by a few pounds or move up to a higher-resistance band.

Exercise 1 -- Wall Squat. Stand with your feet shoulder-width apart, back against a wall. Hold a dumbbell in each hand, with your arms at your sides, palms facing inward. Slowly bend your knees and lower your buttocks 8 inches or more (but do not allow your hips to sink below knee level). Pause, then slowly return to the starting position.

Exercise 2 -- Back Extension. Lie face down on the floor with your legs straight, arms extended flat on the floor above your head, palms down. Keep your nose pointed downward and slowly raise your right leg and left arm off the floor (reach out as well as up). Keep your head and neck in line with your arm. Pause, then slowly return to the starting position. Now slowly raise your left leg and right arm together. Change sides and repeat.

Exercise 3 -- One-arm Military Press. Lie with your back on a bed or bench with your feet flat on the floor, holding a dumbbell in each hand on top of your chest. Press the weight straight up with one hand. Pause, then return it back down. Barely touch your chest, then repeat with the other hand. Alternate sides and repeat.

Exercise 4-- Seated Row. Sit on the floor with your legs fully extended. Hook a resistance band on the balls of your feet. Wrap each end of the band around your hands. Keeping your back straight, pull the band toward you with both arms. Pause, then slowly release your arms straight in front of you again.

Exercise 5 -- Leg Press. Lie on the floor, flat on your back, with your knees hugged into your chest. Place the center of a resistance band on the balls of your feet. Wrap each end of the band around your hands. Keep your elbows close to your sides and squeeze your inner thighs together as you press your legs up toward the ceiling. Pause, then draw your legs back down.

Exercise 6 -- Lat Pull-down. Stand with your feet shoulder-width apart, knees unlocked, and abdominals tight. Grasp a resistance band with your hands slightly wider than shoulder-width apart. Lift your arms just above your head, palms facing forward as you look straight ahead. Extend your arms out to the sides at shoulder height, with your wrists firm and your elbows slightly bent. Pull your shoulder blades back and together and expand your chest. Return to starting position. Repeat.