If I’ve been asked once, I’ve been asked 1000 times: “Is this exercise GOOD for me?” “How about this machine, is it GOOD for me…should I use it?”
The reality is there aren’t any “good” or “bad” exercises; it’s all relative to what you’re training for, and how your training program is constructed to help you reach your goal. For example, if you’re training to run a marathon, running is a great exercise to help you reach your goal, and a bicep curl is a terrible exercise (for the goal of running a marathon). If you want bigger or more toned arms, a bicep curl is a great exercise, and running probably isn’t so great. Now maybe I’m overstating the obvious here, but the answer to “good” or “bad” exercise is contextual.
One of the more (needlessly) debated topics in the resistance training world is the use of machines vs. free weight (dumbbells, barbells, etc.) vs. small apparatus equipment (medicine balls, BOSUs, kettlebells and so on)–which is good, which isn’t good, and what should you do? First and foremost, anyone who actually debates this doesn’t understand the true essence of exercise prescription in the sense that any one of these types of equipment can apply a positive exercise stress to the body and cause the body to make positive changes. It’s all about how the stress is applied (sets, reps, rest intervals between sets, frequency of exercise and so on) and that is relative to your goal.
For example, I could use a series of machines, go one to the next, to the next, to the next, with little to no rest and get a circuit training effect. This would burn calories and aid in developing general muscular fitness. I could use those very same machines, do VERY heavy loads, very low reps, with very long rest intervals and enhance only muscular strength (probably WITHOUT making my muscles a lot bigger). Now the funny thing is I could apply the same parameters (circuit training vs. heavy training) to free weights or small apparatus exercise and get the same effect.
The bottom line is all exercises are GOOD when they’re put into a program properly. Proper exercise prescription is dictated by the training goal and fitness level of the individual. So don’t ever let anyone tell you an exercise is “bad” or “good” in and of itself. It might be “bad” because it doesn’t help you achieve your goal OR could result in injury, but there’s no such thing as a “good” or “bad” exercise.