expression, godan verb (-su)
lift opponent's arms from below to prevent overhand grip on the mawashi
Sumo technique: the wrestler places his arms under the opponent's arms and lifts them upward, disrupting an overhand belt grip.
相手のまわしを取らせないように、腕を返して攻めた。
He attacked by lifting the opponent's arms from below to prevent him from grabbing the mawashi.
Compound of 腕 (かいな, 'arm') + を + 返す (かえす, 'turn back, lift'). The exact historical derivation is uncertain; the phrase is a specialized sumo term.