" Muscle strength and short term power output peak in the early evening (4-6pm) which coincides with daily maximum body temperature. Pain tolerance (at least for arthritis and fibromyalgia) is also highest between 4-5pm."
-Based off of research in Chronobiology with an average waking time of 8:00am, this corresponds to 8-10 hours after waking. In other words, want to add two to three repetitions to your exercises? workout 8-10 hours after you wake up.