After swim practice, we gather to toss medicine balls for about 10 minutes.

The older I get, the more I realize the importance of core strength.

It impacts everything. A strong core supports your spine and improves balance. A weak core means other muscles have to work harder to compensate. That can lead to strains or tears, or throw off alignment.

Who wants that?

I swim four or five days a week with a U.S. Masters swim team at Western Hills Athletic Club. I love our group we swim harder than I ever did as a kid, but we crack up and joke around, too. And lately, after swim practice ends, we gather for about 10 more minutes to toss medicine balls.

I credit Rip Esselstyn, the former firefighter who wrote The Engine 2 Diet, and Jeremy Smitheal, who works in real estate investment, for getting us going.

This morning, eight of us paired up, spread out mats and grabbed medicine balls, which are padded, weighted balls a little bigger than a basketball. We tossed the balls back and forth, trying to focus our effort on our abdominal muscles.

The first time I tried it, my abs screamed after about 10 repetitions. Now I try to do one set of 25 and another set of 12.

I think its making me stronger, and I think its helping my butterfly stroke too.