Starting out, athletes should always err on the conservative side and only perform 10-20 maximal effort jumps in a training session. Because of the explosive nature of a vertical jump, the body can only perform a handful before performance starts to drop. Training beyond this point will not improve jumping height and will only lead to injury. At the completion of a training session, it is generally recommended to rest 48 hours before completing another intense training session.
Because jumping ability is a combination of leg strength and explosive power, jumping can be developed in the same fashion as any other muscular activity. The ultimate limit to how high any athlete can jump will be determined to a significant degree by the distribution of fast-twitch versus slow-twitch fibers present in the muscles of the legs. This distribution is a genetic determination. Fast-twitch fibers are those whose governing neurons, the component of the nervous system that receives the impulses generated by the brain to direct muscular movement, fires more rapidly, which in turn creates the more rapid muscle contractions required for speed. As a general proposition, an athlete with a greater distribution of fast-twitch fibers will be able jump higher than one with a preponderance of slow-twitch fibers.
I just got the bike on Friday and used it twice over the weekend so this isn't a long-term review but my initial impression is highly favorable. I am a "serious" cyclist, which is not to say I'm a professional or anything like that but I log a lot of miles on my road bike and use high-end equipment. I've always hated hooking a bike up to an indoor trainer and I've avoided that type of training for many years. I finally went in on a spinning bike and I am very impressed with the results.