I first used the ENERGY TONIC before going to the gym. I notice an increase in energy during my 20 minutw warm up on the treadmill. Instead of incline at 3.0 I was able to increase incline to 9.0. I don't have that drag feeling during my work out. I'm 72 years old and I work out 5 days a week. I use the product prior to my work out.