1) I agree with the part of the info which said that,

‘ The most common mistake that people focus too much on building is their calve muscles for jumping. If you actually lock your knees and try to jump using only your calves, you’ll quick notice that your calves can only jump you about 4-5 inches high if not less. Your upper legs actually power most of the jump height.’

However, the problem I have with this info is this. If the calves are not very important to your VJ, then WHY TRAIN THEM AT ALL???!!! This is where the author contradicts himself/herself. If the upper legs generate the bulk of your power for your VJ, THEN TRAIN THE UPPER LEGS AND TO HELL WITH THE CALVES!!! Which brings me to my next point.

2) Now I’ve answered questions on improving VJ for a few weeks now, and apparently people are afraid of lifting heavy weights, thinking that weight training WILL make you bulky, slow and awkward. ANY STRENGTH COACH WILL TELL YOU THAT THIS IS A TOTAL LOAD OF BS!!!! The top athletes in almost any sport (except maybe poker or chess), THEY LIFT WEIGHTS!!!!

Kobe Bryant and Vince Carter do > 400 lb squats routinely. So did Michael Jordan. The average NFL defensive back squats 450 lbs and has a 42" VJ. The average sprinter (100m, 200m) and HIGH JUMPER squats 3x their BW. A shot putter bench presses > 400 lbs.

The only way that weight training will make you big & bulky is if your volume is high, e.g. 10 sets of 6 reps or 4 sets of 15 reps of a weight training exercise. This is what bodybuilders do. ATHLETES TRAIN WITH LOW VOLUMES, such as 2 sets of 5 reps with heavy weights to keep their BW down.

The long and short of this point is that, unless you are really light and your legs are naturally strong, YOU MUST TRAIN WITH WEIGHTS. IF YOUR UPPER LEGS ARE NOT STRONG, YOU WILL NOT HAVE A HIGH VJ. So go in the gym, strengthen your glutes, hamstrings and quads with squats and deadlifts, and you will see your VJ improve.

3) High intensity plyometrics help with your VJ. However, plyometrics teach you to improve your VJ by expressing your leg strength better (improving power). However, if you have very little or no leg strength to express, plyos is a waste of time. Get your squat and deadlift up to 2x your BW, then you can think about plyos.

4) Isometrics just teach you to generate tension in your muscles, which is good for weight training, especially in preventing injuries. However, isometrics are not very effective when done by themselves.

These are the main rants that I have about this info. Hope this helps. Here is an article that I think will help you in your quest to improve your vertical. See source below
References :
http://www.higher-faster-sports.com/verticaljumpfaq.html

TECHNIQUE – Do not forget that the body moves all at once to deliver the maximum height of the jump. If your legs are quick but your back is slow to spring up, you will lose on the height of the jump. Most people actually have a very weak back so you’ll have to train it for power! A good strong back doesn’t just spring up fast but it also drops fast as well. Do keep in mind that your jump is generated by 3 different muscles, your back muscles, your upper leg muscles, and your calve muscles. The most common mistake that people focus too much on building is their calve muscles for jumping. If you actually lock your knees and try to jump using only your calves, you’ll quick notice that your calves can only jump you about 4-5 inches high if not less. Your upper legs actually power most of the jump height. Your back however can also jump. You can see for yourself by bending over at the waist and lifting your toes so that you’re awkwardly bent over and balancing on your heels. From here, straighten out your back fast so that your back is springing your body off the ground. You’ll realize that your back muscles can jump you about as high as your calve muscles.

ON TO THE JUMP TRAINING….

Forget about calf raises…just walk around all day long on the balls of your feet and make sure your heels never touch the ground! Yes, do it all day. The first couple days it will hurt like well but soon your body and calves will adjust to it giving you monster strength/stamina there. Make you can get some old shoes and rip off the heel and walk around at home all the time. You don’t have to be tippy-toe like a ballerina, just make sure your heels don’t touch the ground. You should also go running on the balls of your feet. ALWAYS run on the ball of your feet. Especially on flat ground or uphill. Do it on the grass if the concrete hurts too bad.

Forget about weights…you’re looking for power, not strength. Lifting weights makes you get big and slow and use up more oxygen meaning you get tired faster. Also when you use weights it only trains you to be effective when you jump in the exact same direction and range of movement. What you want is overall increase in jump height no matter what angle you jump from. For more proof compare the legs of a bodybuilder versus a high-jumper’s. The jumper’s legs are well shaped and lean but very powerful and move quick. The bodybuilder’s legs are big and strong and can carry a car but they’re just not fast enough to really shoot them into the sky. Again, AVOID weights. Don’t lift weights, and don’t jump around with weight on you. You want RAW POWER, not strength.

Now, you should really do plyometrics….they are silly and slow-looking but they do help. Get a bucket or boxcrate or something and jump from the ground up and then down and then over and side to side or whatever but do those. They help!

Now comes the isometric part part….this is going to be awkard. Find a REALLY low ceiling or like a table that has a ton of stuff on it. Get under the table and bend your back over so that you’re like standing under the table bent over at the waist and the table is on your back as if your about to carry it. The table should also be low enough that you have to bend your knees so your knees can get into the push. NOW! Try to stand up and apply force against the table. (There should be enough weight so that you’re not actually lifting the table.) Push hard against the table for like 15 seconds and then release. Keep doing it. What this is doing is turning your body into like a rubber band. When you push hard but you don’t move, it’s like training your body to store up tons of energy and once the *hold* is released…KABAAM!!!, you fly up like a rubberband.

NOW…….time for the actual high jumping practice. First off, when you jump around on the court, you’re not doing it to good form because you’re probably too occupied with stretching with one arm and throwing your body out of balance so that you can reach the rim. Keep in mind that when you’re practicing your jumping, your goal is to get your CHEST as high as possible. OK! Let’s get to it. First, off get some open flat ground, practicing right by a basketball rim is nice BUT DON’T REACH FOR IT. Stretch your body out first or else you will pull a muscle.

thanx in advance