Muscle groups and their corresponding functions
When you mention upper body, you are referring mainly to the arms. Thus, the muscles in this region will be discussed, and the most important ones are: (1) biceps brachii, (2) triceps, (3) brachioradialis, (4) extensor carpi radialis longus, and (5) deltoid muscle. The biceps is very much attached to the humerus, which is the bone of the upper arm. With that position, it rotates the forearm and flexes the forearm at the elbow. The triceps, on the other hand, is located at the back of the upper arm, and it assists in straightening the whole arm. The brachioradialis covers parts of the upper and lower arms, and it is mainly responsible for flexing the forearm at the elbow. In addition, it helps in the rotation of the forearm both outwardly and inwardly.
The extensor carpi radialis longus is located near the brachioradialis, and it is one of the five major muscles responsible for moving the hand at the wrist in different directions. When you clench your fist, this muscle becomes visible as it rises below your skin. The deltoid is the main muscle at your shoulder, and it controls all movements arising from the shoulder joint.
Strengthening exercises for the muscles in the upper body using body weight
Lie flat with your face against the floor. With the use of your arms, raise your body from the floor until your arms are fully extended. When your arms are fully extended, ensure that your hands are parallel,while your arms are perpendicular, to the floor. From an elevated position, go down to your starting point. Complete two or three sets of five, having breaks in between sets to perform other physical exercises. Gradually, increase your daily goal to sets of 20 or so with the right form .
Reverse push-ups 
Stand with your back facing a table or chair. Place your hands on the table or chair with your extended legs moved forward in front of you. Slowly lower your body towards the table or chair and with your legs slightly flexed at the knees and your heels serving as your fulcrum. After lowering your body as far as you can, you can return to your starting position. Do 10 to 20 times. To increase the difficulty of this exercise, you can select another support which is lower than a chair or table. A good suggestion is a bench. Before starting this exercise, however, ensure that your support is in good condition and stable so that you will not be injured. This specific exercise is intended for the triceps which are located at the back of the upper arms .
The quadriceps are group of four muscles located at the front of the thigh. These muscles are: (1) vastus lateralis, (2) vastus medialis, (3) vastus intermedius, and (4) rectus femoris. Each of the vastus muscles is attached to the femur, which is the primary bone of the upper leg, and is attached down under in the patella or the kneecap. The rectus femoris is also attached to the patella; however, in the higher portion, it is attached to the hip bone—and not to the femur.
As suggested by their location, the quadriceps are very important in extending the lower legs at the knees. In addition, these are used for walking, running, and other physical activities; hence, they are prone to injuries, such as strains, tears, and ruptures .
(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.