Swings for grip and cardio

Which is better for grip and cardio: one handed or two handed swings? My goal is to get a better grip, but also get some heavy cardio work in as well. I pull security and need grip to grab hold of people, but also cardio fitness for the people who feel they can out run security guards. Most of them do because the team I was assigned to were a bunch of slow and big muscle heads. They feel they can out run my team, so that is where I get called in. I catch up to them and take them down. That is kind of where I got the nickname snake. Anyways, I am trying to get a better grip and cardio for this work. However, I do not know whic type of swing is better for my goal. I am comfortable doing both, but I just need one for my goals. Maybe I can do both, but I would not know how to do them both and run about 30 minutes in one workout. If I do should I do two handed swings, then run, and then finish with one handed swings? If so, how many swings should I do for both because I do not want to overtrain and possibly hurt myself that will not only lose my job, but hurt my goal to join police. Any suggestions?