I think this is nothing more than an advertisement, which makes it worse since it shows that whoever is peddling this doesn't know much about what he/she is talking about. There are two very strange physics in here and they both occur in the same paragraph.
Being Able to slam dunk is almost as much in the mind than it is in the legs but in the end it comes down to one thing – power. In physics power is strength x speed. Strength is the amount of energy that your legs can push up with and speed is how long it takes to push out the strength.
Close, but no cigar.
In physics, Power = Energy/time, or Force*speed. And "speed" isn't "how long it takes to push something", which is really a quantity of time, not speed. It is really the time rate to move something.
Again, this is basic, intro physics that first year college kids, or even high school kids, would have come across. The terms "power", "energy", and "speed" are very well-defined at this level. One simply can't just mix things up as one pleases. So for this person to invoke "in physics...." and then proceeded to mess things up is really astounding.
I don't know about you, but I certainly won't buy whatever it is that is being peddled here. :)