Physical Fitness Stack Exchange is a question and answer site for physical fitness professionals, athletes, trainers, and those providing health-related needs. It only takes a minute to sign up.
Sign up to join this community
Consider a person who can't make a routine plan to go to gym (because of a lot of personal problems) who wants to get in shape, a really good and fit shape and gain muscle.
As that person you can search and see hundreds of exercises with body weight all over the Internet.
Now my question is, why do we need dumbbells and other weights? What they offer more than body weight for fitness and gaining muscle programs?
Two words - progressive overload.
With bodyweight exercises, no matter how hard you try and how fancy you go with exercise, eventually you will hit the limit in muscle and strength growth because you will not be able to apply resistance sufficient enough to cause the process of muscle tissue damage and repair, i.e. muscle growth. You'll be limited by your own body weight.
On the other hand, with free weights you are absolutely not limited in anything except your genetics and physical abilities. You can continue loading the bar infinitely even by the smallest possible increments and still have enough resistance for your muscle and strength growth.
Don't think though of your muscle and strenght growth as in y=|x| function. It's more like y=sqrt(x) function.
Bodyweight skills definitely have an upper limit, unlike weightlifting which is limited only by how many plates will fit on the bar, leverage can be varied quite a bit, increasing the difficulty of these skills. Progressive resistance makes you stronger. It does not matter if this comes from varied leverage, or extra weight.
Both bodyweight and barbell training will help you gain muscle but for example with squat you cannot add more resistance with bodyweight to develop raw power.
Also, its well established that for barbell training, if done correctly at high intensity, will stimulate more muscular growth than bodyweight exercises for the same muscle groups.
There are many stories of people who don't weight train and end up lifting very large amounts their first time out, due to body weight skills. Here is a video of Ross Enamait deadlifting 495lbs (at 170lb body weight) with no deadlift skills and a primarily bodyweight-only training routine.
Simply, it's going to take me too long to develop the strength to squat 495lb if I go down the bodyweight-only route compared to if I were to go down the barbell route.
Technically, we don't, but for some people, that works better for them or is more enjoyable. With so many different kinds of weights and ways to employ them, if it is your desire to isolate and overload specific muscle groups, that will be much easier with weights than natural body movements which tend to incorporate more of the body.
Some muscles are simply not possible to train with just your body. How would you train your deltoids, traps, obliques without using any kind of resistance? To create a aesthetic look, you need to train muscles you can't target properly using just your body. As others have pointed out, there is also a limit to how much you can stimulate a muscle to grow without increasing the resistance.
