Throwing a ball - What makes a good arm?

The expression “good arm” generally means the distance someone can throw a ball and at what speed he can do so. What exactly determines someone’s ability to throw a ball harder and faster than someone else? Muscle mass? The physics of one’s arm & shoulder? Can someone increase his/her “arm” via certain exercises?

Golf certainly requires no huge amount of muscle mass; it’s all technique. I imagine throwing a ball is exactly the same: all physics.

I would say:

  1. the ability to time all the muscles in the body to convulse/relax (nearly) simultaneously in order to put as much energy into the ball as possible
  2. flexibility in order to extend the amount of distance and time one is in contact with the ball in order to place as much energy as possible into the ball

and lastly and probably most importantly, especially for pitching:
3. control of fine motor ability to accurately release the ball in the correct trajectory or with the correct spin.

If you mean the difference between “throwing like a girl” and a normal throwing motion, it is all technique and muscle memory. Ball placement, leading with the elbow and snapping the wrist.

If you mean the difference between a high school pitcher and a 120 million dollar contract; I can’t back this up but I heard at one point a lot of studies were being done on the length of tendons in the arm, where the tendons were attached and the ratio of bone length to tendon length.

(I know “throwing like a girl” is not true but it’s the only way I can think to describe what we have all seen, and “throwing like your using your non dominant hand” just doesn’t have the same ring.)

In throwing, particulary baseball pitching, the power comes from the legs. This may not be intuitively obvious, especially with phrases like, “He’s got a good arm.” The legs rotate the body to allow the arm to follow in a whipping motion. Try throwing from a seated position sometime and you’ll see what I mean right away. Sure, the motion of the shoulder, arm, and wrist are critical and have to have the correct timing and coordination, but the legs make the difference in the power.

Much the same is true of batting, and the golf swing. The legs power the motion, the hips follow, and the upper body becomes the whip.

Put in a simpler way, I can throw a ball from the outfield on a fly “X” number of feet. What, if anything, can I do to increase the distance?

The ability to throw hard is a natural thing, mostly luck of birth. A good arm translates into hitting balls farther, longer drives in golf and hitting racquetballs harder. People with poor arms have to rely on learning the proper technique. But are limited .
Most coaches say you can not teach running peed and how to throw hard. Tecnique will help .but you have natural limitations.

Make sure you have good form. Go to the weighlifting room and do squats. Do exercises for shoulder flexibility. Choose your parents carefully.

Some gains can be had from strength training in the gym, though you don’t want to overdo it and end up so bulky as to restrict your arm motion. Particularly shoulder and triceps exercises, as these are the main muscle groups active in the throwing motion.

Aside from gym work, throwing long distance with regularity will help. This is often called “long toss” and involves you and a partner starting close in at a normal distance for playing catch and slowly backing apart until you are just barely getting it to your partner. Throw some balls back and forth at this distance and then reel it back in, throwing shorter and shorter distances until you and your partner are to where you started.

There are, of course, a lot of natural factors as well, you’re not gonna be pumping it up there at 100MPH no matter how much you work on it, some people are just more naturally gifted. But there’s definitely room for improvement if you work at it.

There are “good” arms and there are “major league” arms. Scouts have trained to know the difference.

The power comes from the legs. The fine motor skills that determine spin and accuracy come from the brain, shoulder and arm. If they all work together there is a career in it. If not, struggle.

I’d agree with most of the previous posts. Like every good American boy, I played little league for a few years (3rd base, mostly) and wasn’t bad. Then I left for a sport that didn’t involve a ball (wrestling). Fast forward 20 years, and… well, I throw like a girl. My muscle memory for that action is shot to hell.

Heh. Now that I think of it, my father (who never played any organized sports - just “pick-up” games) always kind of had a hand grenade throwing motion. Perhaps he retained muscle memory from a different place.

There are weighted balls available that purport to strengthen the muscles used in throwing. Most improvements will come by changing form such as by striding correctly, sufficient shoulder and hip turns, and keeping your shoulder closed for the correct amount of time.

Former coach here. It’s largely about hip flexion.

Forget about being a major leaguer. Most people who don’t throw well lack leg and hip movement. With kids, you have them stand sideways to the target so they have to step and twist as they throw.

Also, have them throw at something FAR AWAY. This requires good biomechanics, and makes it more likely they’re going to start using the right body parts.