Another reference:

http://www.trainingcorner.com/prevwks_nf.html :

" Are you a morning person?

  You may not have much leeway, given you work schedule and other
  commitments, but is it better to train in the morning, afternoon or
  evening?

  Edmund Burke[*], director of exercise science at the U. of
  Colorado, gives the thumbs-up to a.m. workouts.
  He says that on an empty stomach, you'll draw more from your fat
  stores and continue to burn fat during the day.
  Burke adds that many people also have greater energy throughout the
  day following a morning workout. "

  [* has bio at http://www.optimalmusclerecovery.com/about.htm ]

Philip Thrift
http://www.paleofitness.com