The human brain lays down physical nerve pathways for motor skills. They even show up when the brain is examined.

But you need about 3 months for this basic growth to occur. After that, the more you work at the practising of the skills, the more instinctive they become, and the stronger the pathways grow.

Actually, since much of this growth (a fat insulating layer around the nerves fibres in the pathways which increases their electrical insulation, and the effectiveness of carrying the electrical signal) is sourced from Omega 3 based fat, you should make sure your diet includes sufficient Omega 3 - a good source is fish oil, or just eat fish a couple of times a week.

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As an ex-ASMF Sports Trainer, I can also tell you that the rule for growing muscles in the gym was:
"A day break a week: a week break a month: and a month break a year".

Muscles grow ONLY when resting: the stress of exercise actually causes real physical micro-damage which the body will repair and increase strength and bulk when resting; if no rest period occurs, you get the physical side effects of 'over training' - cramp is then the very least of your worries, merely a mild warning symptom...