By Craig Ballantyne. In general, there is no best time to workout. Training in the afternoon should get you the same results as training in the morning, all other things being equal (i.e. nutrition, workout intensity, etc.).
Here are some important considerations for determining your workout time:
a) Are you able to train with at a proper intensity or are you tired?
b) Will you be able to eat properly before and after your workout time?
c) Will you stick to your workout program?
d) Will exercising in the morning be hard on your back?
Why do I bring up point "d"?
Dr. Stuart McGill, an expert in low-back disorders, recommends waiting at least an hour after waking up before engaging in any exercise that includes trunk flexion (i.e. traditional ab exercises such as crunches). Overnight, the discs between your vertebrae fill with fluid and are more susceptible to injury in the morning. That's the reason behind this recommendation.
So don't roll out of bed and start doing sit-ups (not that most people should be doing those anyway - and as you'll notice in my reports, I don't include sit-ups in the programs). If you choose to exercise in the morning, you'll be fine if you pay attention to your form and exercise selection (just as you should no matter when you exercise).
If you have soreness in the lower back, it is also a good idea to avoid bending over early in the morning (use another posture that is more back friendly when putting on your shoes, socks, picking up dumbbells off the floor, etc.). Always use proper lifting posture when training - no matter what time of day.
Basically, the bottom line is that you can still workout in the morning as long as you are extra careful of your back and lifting technique.
Craig Ballantyne is a Certified Strength & Conditioning Specialist and writes for Men's Fitness, Maximum Fitness, Muscle and Fitness Hers, and Oxygen magazines. His trademarked Turbulence Training fat loss workouts have been featured multiple times in Men’s Fitness and Maximum Fitness magazines, and have helped thousands of men and women around the world lose fat, gain muscle, and get lean in less than 45 minutes three times per week. For more information on the Turbulence Training workouts that will help you burn fat without long, slow cardio sessions or fancy equipment, visit www.TurbulenceTraining.com