The guy gets into the pool and swims a furious crawl to the other end of the lane. He then stands there and bobs up and down about a dozen times before swimming back to the head of the lane. Then, he stands there and bobs up and down. He does this over and over.
Can anyone tell me what he is achieving by this bouncing up and down? I can see he could get his heart rate up but the swimming alone would do that. Is this some kind of recognized drill that I haven't heard of?
