400 METERS
44.69 Darrell Robinson (Wilson, Tacoma, Washington) 82
45.01 Jerome Young (Prince Tech, Hartford, Connecticut) 95
45.09 Henry Thomas (Hawthorne, California) 85
45.14 **Obea Moore (Muir, Pasadena, California) 95
45.17 *William Reed (Central, Philadelphia, Pennsylvania) 87
45.25 Calvin Harrison (North, Salinas, California) 93
45.25 LaShawn Merritt (Wilson, Portsmouth, Virginia) 04
45.36 Chris Nelloms (Dunbar, Dayton, Ohio) 90
45.36 Marlon Ramsey (West Brook, Beaumont, Texas) 94
45.44 Xavier Carter (Palm Bay, Melbourne, Florida) 04
I think the 50% split for anaerobic vs aerobic occurs around 75 seconds so it might be possible. I'm not saying he did it, but it might be possible to do when you run 45 seconds. I know Olympic swimmers hold their breath during the entire 50 meters which lasts 22-23 seconds for men and 24-25 for women.