You and another responder find an unresponsive adult on the floor in the locker room. you size up the scene, form an initial impression and perform a primary assessment. you find the victim is not moving or breathing, but has a pulse. you should summon ems personnel, then:

Give ventilation's at a rate of 1 about every 5-6 seconds.

Explanation: Cardiopulmonary resuscitation (CPR) is a lifesaving technique useful in many emergencies, including a heart attack or near drowning, in which someone's breathing or heartbeat has stopped. Both trained and untrained personnel can perform CPR.

If you're not trained in CPR, then provide hands-only CPR. That means uninterrupted chest compressions of 100 to 120 a minute until paramedics arrive without gibing rescue breaths.  

If you're well-trained and confident in your ability, check to see if there is a pulse and breathing. If there is no breathing or a pulse within 8-10 seconds, begin chest compressions. Start CPR with 30 chest compressions before giving two rescue breaths.