When designing your training program, you are faced with the decision of choosing a set of exercises for properly training each muscle group. There are a great amount of different exercises (probably several hundred), thus complicating this selection. This post presents some issues you must take into account for performing an adequate exercise selection.
Exercises can be classified depending of the type of movement performed. On one side, compound exercises involve two or more joint movements and thus stress several muscle groups. On the other side, isolation exercises involve only one joint movement at a time, stressing only one specific muscle. Compound exercises are superior to isolation in building muscle mass. However, although you can build plenty of mass using only compound exercises, isolation work is mandatory for a complete muscle development, because it allows emphasizing on every muscle striation. Your routine for a given muscle should include movements that hit that muscle in different ways and from different angles using both compound and isolation movements. That is why you should include 2-3 exercises when you work each muscle.
Some movements offer the possibility of being performed using free weights (barbell and dumbbells) or machines. Free weights provide a more complete work and are better at preventing muscle imbalances, since they involve stabilizer muscles more than machines. Therefore, the basis of your routine should be using free weights. Machines have to be minimized except of some exceptions like the cable station and the leg extension, but don't look down on machines because they can be used to introduce some variety occasionally.
Your selection should avoid dangerous exercises that can lead you to injury. There are some popular exercises (e.g. behind-the-neck pulldown or behind-the-neck shoulder press) that involve movements with wrong biomechanics, being a chance to injury yourself. In a future post, I’ll go deeper in the trouble with these exercises.
However, your exercise selection should not be immovable. The muscles grow because they accustom themselves to the stress being put onto them. If you train a muscle always in the same way, your progress will slow, and possibly even halt because your body adapts to the motion, and no longer needs to build new muscle to do that motion. The key is varying your workouts every 4-6 weeks by altering one or more factors (i.e. number of reps, sets, tempo, exercise selection, etc.).
For supporting your exercise selection process, you can find a comprehensive exercise directory in the
“Exercise Instruction & Kinesiology” section of
ExRx.net site. Each exercise description contains the preparation and execution instructions (demonstrated with an animated gif), the involved muscles and the exercise classification (compound/isolation, push/pull, etc.). The
Bodybuilding.com site provides another complete exercise directory in its
“Exercise Guides” section, including video guides for describing the exercises correct execution.