A few years ago, research started coming out about the effects of common OTC painkillers effects on muscle growth. If you are new to bodybuilding in recent years, you may have missed the big news when it first came out. Many bodybuilders take them to relieve DOMS (muscle soreness) from weight training or some other ailment and don’t know about this side effect. This is also important to know because many fat burning supplements, such as hydroxycut hardcore, put willow bark ( natural form of aspirin ) in it. Acetaminophen ( Tylenol ) and the class of drugs called NSAIDS , which includes the OTC painkillers, ibuprofen (Advil, Motrin) and naproxen ( Alleve ), all have an effect on protein synthesis.
Studies on painkiller effects on protein synthesis:
One of the first studies to come out was published in
J Clin Endocrinol Metab. 2001 Oct;86(10):5067-70. It was done on 24 males to either receive ibuprofen, acetaminophen or a control after resistance excercise workout (10 – 14 sets). It showed that acetaminophen and ibuprofen had an impact on prostoglandins (in equal degree). Researchers concluded this impact on prostoglandins could have a big impact on muscle growth.
One year later, these same researchers published (Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E551-6.) measuring protein synthesis after resistance workout. The study was done on 24 males who either took acetaminophen, ibuprofen, or control. Results showed that the placebo group had 75% higher protein synthesis at the skeletal muscle than the ibuprofen or acetaminophen group. These painkillers didn’t effect overall body breakdown, but did effect protein synthesis at the muscle.
Aspirin also has a effect on decreasing protein synthesis. (source: J Biol Chem. 2007 Apr;282(14):10164-71. Epub 2007 Feb 6.)
Most of the older studies discuss protein synthesis, but a more
recent study published in (Med Sci Sports Exerc. 2006 May;38(5):840-6.) compared overloading a rat muscle with or without ibuprofen on actual muscle growth. Results showed reduced muscle hypertrophy (muscle growth) by 50% in rats from ibuprofen with overload vs. overload only.
As you can see these were not minor changes in protein synthesis. Even occasional use will have a significant impact on muscle growth.