I've wondered the same thing about twice-a-day workouts and my metabolism. I can't ride my bike to work, it's a 60+ mile commute. I wish I could!

Normally I do one 45-90 minute workout a day, 6 days a week. But most of my day is spent sitting at a desk. I wonder what kind of stress that puts on my body to be sedentary for 23 hours then suddenly do an intense workout for 60 minutes?

I've been so busy lately, I've had to break-up my working out into two 20-40 minute workouts, one in the AM and one in the late afternoon. I seem to have more energy throughout the day . . .

I can't tell you how its affecting my weight right now as I'm 8 months pregnant and as large as a boat.