I think here is a mistake.

[v0031]

Have you ever heard of a "heavy athlete"? No, it's not an overweight ballplayer; it’s someone who takes part in traditional Scottish games. The Highland Gaines in Ligonier. Pennsylvania, offer plenty of heavy athletes the opportunity to compete in events like tree-throwing. How would you like to throw a tree?
By the time of the Revolutionary War, it was said that one out of every three people living in western Pennsylvania was of Scottish ancestry. Today, the people of Ligonier celebrate their Scottish heritage by holding the Ligonier Highland Games. The most popular games are called "heavy athletics". These games are a test of strength and skill for those who compete. Ancient Scottish leaders, chieftains, originally used Highland games to carefully choose the best men to go into war. But in Ligonier the games are just for fun!
Heavy athletes do things like throw big stones or even hammers to see who can throw the farthest. They also compete in a game called the caber toss. Caber is Gaelic the traditional language of Scotland for tree. The caber used in the Ligonier Highland Gaines is a tree trunk more than 14 feet long!    

I think the red should be throwing.

[FairBol]

Hmm...since the subject seems to be in the present tense, I'd say "throw" and not "throwing" is correct.  "Heavy athletes do things like throw big stones"

Example: "The pitcher is about to throw the ball" (in this sentence, "the pitcher" is the subject, and in the present tense...he hasn't thrown the ball yet)

[Dr. Arch]

Linguist here. That "throw" is in the bare infinitive. Only one verb per clause may have tense assigned to it, and for this clause, the main verb is "do," which is in the simple present. "Like throw..." is an adjunct phrase and does not have tense. As such, "throw" does not have tense.

You can further test this observation by translating the sentence to a more morphologically complex language, like Spanish.

The sentence reads: "Atletas pesados hacen cosas como tirar piedras grandes..." "Tirar" (throw) is in the morphological infinitive.