Muscle groups and their corresponding functions
Strengthening exercises for the quadriceps using body weight
Sitting leg extensions
Sit on a chair or on the edge of a table. Extend your one leg and tighten it, holding your kneecap parallel to the floor. Tighten your muscles for 2 to 3 seconds in isometric contraction—wherein there is no movement at the joint but the muscle fibers are working or contracting. Complete 10 to 20 times. You can repeat the same procedure with the other leg. If you believe your legs have grown stronger, you can add a 2-pound ankle weight and do the physical exercise .
Stand with your feet around one foot apart, and then slowly squat to one-fourth or one-third of the way down and hold for 2 or 3 seconds before slowly returning to the starting or standing position. Complete 10 to 20 times. Do not squat exceeding halfway down to avoid injury! To provide yourself with added protection, you can do chair squats wherein you can lower your buttocks slightly over the chair and proceed doing the full exercise as described in the preceding.
The principal muscle in the buttocks is the gluteus maximus, and it is regarded as one of the strongest muscles in the human body. It is attached to the coccyx, otherwise known as tailbone, and to the nearby bones. It is responsible for the movement of the hip and the thigh. Specifically, it aids in standing up from a sitting position, climbing stairs, and in maintaining erect position. Other muscles in the buttocks are gluteus minimus and medius.
Strengthening exercises for the buttocks using body weight
Butt raisers 
Lie on your back with your knees bent and your feet flat on the floor. With your heels serving as the fulcrum, raise you pelvis one inch off the floor and hold it for 10 seconds, release and relax. Do this exercise for 5 to 10 times .
Lie flat on the floor in supine position, with your knees bent and your feet flat on the floor. Simultaneously tighten your butt muscles and your abdominals while raising your pelvis from the floor. While raising your pelvis, press your lower back towards the floor. Hold contracted muscles for 3 to 10 seconds while exhaling. You can do this for 3 to 5 times .
Hips and groin[1,2]
The most prominent muscle in the groin is the gracilis. It is quite a long muscle because it extends from the pelvic bone up to the bone of the lower leg. Its main functionsare to assist in knee flexion and to adduct the legs. Adducting the legs means bringing them from the outside toward the center; hence, it means bringing the feet and legs together at the center. It is also responsible for stabilizing and rotating the knee inward. Aside from the gracilis, there are other important muscles in the groin. These include the pectineus, adductor brevis, adductor longus, and the adductor magnus.
Strengthening exercises for the hips and groin using body weight
Inside leg raises (for the adductors) [1,2]
Lie on your right side with your head resting on the outstretched right arm and your left arm aligned with your body. Flex your left leg at the knee and place the left lower leg in front of the right upper leg. Slowly raise your stretched right leg as high and as far as you can and then slowly returning to the starting position. Complete 2 or 3 sets of 10 with each leg. If you feel that your adductors have gained strength, you can add weight in your ankle to increase the resistance.
(To be continued)
- Glover B, Shepherd J, Glover SF. Strengthening. In: The Runner’s Handbook. 2nd revised ed. New York: Penguin Books USA Inc.; 1996:578-597.