The word for today is GYMNASIUM which comes from the Greek word GYMNOS – which means – THE PLACE OF THE NAKED. In ancient times the Greek athlete worked out and exercised in the raw, i.e. without any garments. The tunic or toga did not lend itself to such exercise as spandex does today.
The word ATHLETE comes from the Greek word ATHLON – which means – CONTEST, STRUGGLE.
Therefore a DECATHLON means TEN EVENTS or TEN STRUGGLES. A TRIATHLETE is one who competes in THREE EVENTS.
The Greek word for WRESTLING is AGONIA, and that gives us the connotation of pain as in the word AGONY.
Also we have the words PROTAGONIST and ANTAGONIST. In dramas and stories we have characters and the protagonist is the first wrestler, and the antagonist is the one who wrestles against him or her. The Greek word PROTO means FIRST, and the prefix ANTI means AGAINST.