I’m going to buck the normal trend here and say loose all the long distance running. Forget it ever existed (you’re welcome). Long distance exercise is counter-intuitive to the development a pitcher needs.
Switch to a sprint based workout/training regimen. A pitcher is nothing more than a VERY short distance sprinter… i mean think about it. They walk around the mound… toe the rubber, come set… then WHAM a 2 second sprint… then they walk around on the mound again, some time passes, they toe the rubber, come set, then WHAM another 2 second sprint. A pitchers outing is nothing more than 100 super short sprints with nice breaks in-between each sprint. And even longer breaks every 15 pitches or so (between innings)
Really what you are dealing with is aerobic vs anaerobic respiration. Not to get into too much scientific detail, long story short, when long distance running you are training anaerobic. Pitchers literally NEVER reach an anaerobic state so you are essentially training something you will NEVER use on the mound (what a waste of time right?). What pitchers do utilize is aerobic facility. In a nutshell, a short sprint, the muscles are never starved of oxygen.
So first off, train in short sprint, high-intensity type exercise rather than long distance or extended. Short interval training with long breaks between intervals is great for pitchers. And by short I mean seconds. Maybe 5-10 secs of SUPER high intensity and then a break for a min or so to fully catch breath before repeating. You literally need zero equipment other than a stop watch or an interval trainer phone app. If you do 2 interval training sessions a day for 10-20mins each session you will be amazed at how quickly you will start to see results.
It’s ok if you are unsure of heavy balls at the moment, I think you have a lot of lower hanging fruit that will give you better gains than them right now anyways.
Arm bands really are an absolute necessity. You can have your body in tip top shape but if the supporting intricate muscles and tendons in your arm can’t handle it you are going to end up with a VERY short career. Plus they will indeed add velocity. In the name of full disclosure we specialize in arm bands and more detailed info on them, and workout videos, is on our site: http://jamzbandz.com/index.php/product/baseball-bandz/ (since things are tight put ‘ship’ in the coupon code at checkout for free shipping, will save you $5). If I asked you if you wanted to add 2-4 mph velocity to your fastball for $30 would you do it? Eat Ramen for a couple of days instead of Taco Bell and consider it an investment in your future!
Throw, Throw and throw some more. Even if it’s throwing/tossing a bucket of balls into the side of a batting cage. You don’t have to have 2 people to throw.