Hot answers tagged muscle-mass
Increasing 5-7kg in 2 months is something you can do while staying pretty lean. To increase primarily upper body mass and still maintain your vertical jump is also pretty easy. Diet Your diet needs to change so that you are increasing your mass by no more than .75 kg a week. That will keep you pretty lean, so it won't adversely affect the vertical too ...
Considering that one of the biggest improvements you can make for improving your vertical jump is to get strong (PDF), I'd say there's no problem with gaining upper body muscle mass at the same time as you improve lower body strength. Get started squatting, deadlifting, chin-upping, and dipping.
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