I am just finishing week 1 after a 2 week layoff from a short cycle..
To say the least i am very impressed. I had stopped taking the amplify 02 as my preworkout so that i could measure the complete results of the product, and although i didn't add more weight or reps, i didn't lose any..
now that i have added the amplify 02 back into my normal workout routine, i would say my concern is possible over training.. recovery is getting better and better, and strength increase is starting to happen again..