Strengthening physical exercises are movements that you need to do repeatedly in order to develop and improve the strength of a group of muscles. The groups of muscles are abdominals, ankles, arch, back, buttocks, calf muscles, hamstrings, hips/groin, quadriceps, shins, and upper body. As to which group(s) of muscles you would like to develop depends on your purpose. If you would like to be a good runner, then the groups of muscles that you need to strengthen are the calves, hamstrings, and buttocks. If you would like to firm up your abdomen, then you strengthen your abdominals. If you would like to have firm and sturdy shoulders and chest, then strengthen your muscles in your upper body.
Means of doing strengthening exercises
Using body weight
In this method of strengthening exercises, you do not use any gym equipment and gadgets. You use your own body to do them. Examples are modified sit-ups, reverse sit-ups, pelvic tilt, ankle push, towel sweep, and many more. This means that you can do these exercises at home, without even going to the gym.
Using free weights 
In contrast to the exercises using your body weight, you may need to report to the gym if you will use the free weights. Generally, there are two kinds of free weights that you can use: (1) handheld dumbbells, or (2) the weight plates on barbells. The need for gym in these exercises is not solely due to the availability of these equipment; more importantly, there are personnel in the gym who could guide you on how to properly use these equipment.
Using body weight and free weights will not totally strengthen all of your muscles. In addition, you will use some machines which are intended to strengthen other sets of muscles. Examples of these machines are the biceps curl machine, triceps machine, pull-down machine, and many others. When you visit the gym for the first time, you can look around and familiarize yourself with these machines. Each machine has its own use and purpose. Use it (them) if it (they) is (are) what you need. Thus, before using any machine in the gym, consult any fitness adviser around so that you could be guided accordingly.
Muscle groups and their corresponding functions
The abdominalsare muscles located in the front section of your abdomen. Their function is to provide you with postural support, protect your internal organs located in the abdomen and pelvic area, and to allow you to perform some movements, such as rotating the spine, bending, breathing, and defecating. The most prominent muscles are the rectus abdominis, external oblique muscles, internal oblique musclesand the latissimus dorsi.The rectus abdominis runs downward from the sternumdown to the pelvic bone, and the external oblique muscles are located at its sides, running downward in oblique direction—hence, the word external oblique. Beneath the external oblique muscles are the internal oblique muscles. Covering the back is the latissimus dorsi muscle.
Figure 1.0.Diagrammatic illustration showing the major muscles in the front abdomen.
The rectus abdominis is activated when you do crunches because it is responsible for pulling the rib and the pelvis toward each other. In addition, it curves the back. In terms of bodily functions, it is very important during the delivery of your child, for bowel movements, and for coughing. When you have a bulging belly, the accumulated fat is lying over your rectus abdominis. Thus, when you do periodic physical exercises for the abdominals, the fats will be burned, and you will see the exposed rectus abdominis as a six-pack muscle.
- Glover B, Shepherd J, Glover SF. Strengthening. In: The Runner’s Handbook. 2nd revised ed. New York: Penguin Books USA Inc.; 1996:578-597.