Started off slow with little to no noticeable results, although workouts were chest and shoulders. Triceps had more noticeable pump but still mild, as was biceps a couple workouts later. Back around to triceps workout today and pump was a lot better. First two exercises pumped up pretty good, third set dropped reps from arms tightening up. Decent pump by end of workout but didn't last long. I've used other products that give quicker, better, longer lasting pumps, although most have stimulants for energy that led to anxiety attacks. This product does not contain any of those substances so if you are looking for something that will give decent results without the shaky feeling some products give, this may be good for you. Interested in seeing the results over a longer period.