Hello, Thank you for writing to us, Masturbation only becomes a problem if it becomes a substitute for other forms of sexual activity. It is a perfectly normal and healthy form of sexual expression. Ninety-five percent of men begin to masturbate at puberty, and many continue to do so throughout life without negative consequences. Conclusively, yes it can and will reduce your stamina, it is best to be done when you are not training or close to training, instead you should do it while you are resting over the weekend (or whenever you rest.) With limiting the amount you masturbate keeping you focussed on your athletic goals and helping you by producing more testosterone. Hope you find my answer helpful here, Thanks & Regards, Gaurav Prajapati