Friend of the blog Tom Moore did some digging on Sam Hinkie's athletic days for the Bucks County Courier Times, and it turns out Yung Hinkie (patent pending) hit the weights hard to offset his diminutive size:
He couldn't have just walked out on the court or field and competed with other kids at the time without putting in the behind-the-scenes dirty work, [Defensive coordinator Kenny] Ridley said. He spent tons of time in the weight room. By the time he was a senior, he squatted close to 500 pounds. He was always looking for things to make him better, individually. He maximized his ability.
There are a ton of great details in the piece on Hinkie's backstory, so you should definitely check out the full piece here.