Height plays no significant factor in a person’s ability to grow muscle. Whilst shorter people may appear to have gained more muscle in less time, it’s simply because they need less muscle to fill out proportionally. In contrast, a taller individual with longer limbs may take more time to fill out.
The most common cause of sharp knee pain when squatting is patellar tendinopathy. The patellar is a ligament that connects the patella to the tibia, and overuse can cause the tendon to wear and inflame, resulting in sharp pain just below the kneecap.