Do Pain Killers Put The Brakes On Muscle Growth?
Over-the-counter pain killers are a popular way to ease the pain and soreness that manifests itself 24-48 hours after a tough workout.
However, what most people don't realize is that high doses of these pain killers have been shown to "blunt" the normal rise in protein synthesis that occurs after exercise.
In other words, while they can control the pain, regular use could put the brakes on muscle growth.
But there's a "twist" in the tale.
While I was researching the answer to a question for one of my Mentor Members, I came across a more recent study showing that the very same pain killers can actually SPEED UP muscle growth.
So what's going on? Are pain killers good or bad for muscle growth?
Here's a closer look at both sides of the story...
Pain killers and muscle growth
The way in which pain killers are thought to affect muscle growth is by limiting the rise in protein synthesis that normally occurs after exercise.
In simple terms, your muscles grow larger when
protein synthesis is greater than protein breakdown.
Think of your muscles a bit like your bank account. Money coming into your account is
known as protein synthesis. Money leaving the account is known as protein
When there's more money coming into your account than there
is going out, you'll end up with a bigger bank account. In much the same way, when protein synthesis exceeds protein breakdown, you'll end up with bigger muscles.
Although there are a few studies linking pain killers to a reduced rate of protein
synthesis, the one I want to look at in more detail comes from the American Journal of Physiology .
A group of male subjects with an average age of 25 were assigned
to one of three groups. All groups performed 10-14 sets of 10 eccentric
repetitions for the muscles on the front of the thigh.
After completing the workout, group one received the maximal
over-the-counter dose of ibuprofen (1200 milligrams daily).
Group two was given acetaminophen (4000 milligrams daily).
The third group received a placebo (a "dummy"
supplement) that contained no active ingredients.
Each drug was administered in three doses each day (8 AM, 2 PM, and 8 PM) corresponding to the maximal over-the-counter daily dose. The placebo group was given the same number of pills, which were indistinguishable from the drugs.
When muscle samples were analyzed 24 hours after exercise, the increased rate of muscle protein synthesis normally seen after resistance exercise was reduced in subjects given the pain killers.
You can see this for yourself in the figure below, which shows muscle protein synthesis before (white bars) and after (black bars) exercise (ACET = acetaminophen group; IBU =ibuprofen group; PLA = placebo group).
In other words, it appears that pain killers can limit the ability of your muscles to synthesize protein and repair themselves after exercise-induced muscle damage. And if they inhibit recovery, they also have the potential to put the brakes on muscle growth.
But, as I mentioned earlier, there's a "twist" in the tale...
Remember, this was a short-term study that looked at protein synthesis in subjects using pain killers for just 24 hours.
And while this type of research is useful when it comes to generating ideas and theories about what might happen over a longer period of time, it's only one piece of the puzzle.
A follow-up study, this time done over a period of three months, shows that a daily dose of pain killers actually ACCELERATES gains in both muscle size and strength among elderly men and women who lift weights .
The researchers tracked 36 men and women between the ages of 60 and 78 who enrolled in a three-month resistance-training program at Ball State University's Human Performance Lab.
Subjects were randomly divided into an acetaminophen group, an ibuprofen group or a placebo group. The two drugs were consumed at recommended daily dosage levels.
To the research team's surprise, an analysis of muscle tissue samples taken before and after the training program revealed that those taking either acetaminophen or ibuprofen got better results than the placebo group.
"It's surprising," says study co-author Todd A. Trappe, an associate professor with the Human Performance Lab at Ball State University.
"Over three months, the chronic consumption of ibuprofen or acetaminophen during resistance training appears to have induced intramuscular changes that enhance the metabolic response to resistance exercise," he continues. "This allows the body to add substantially more new protein to muscle."
So on the one hand we have a study that appears to show one thing... and a second study that, at first glance anyway, appears to say the precise opposite.
What's going on? Should you run out and start downing over-the-counter pain killers in an attempt to boost muscle growth?
I don't think so, as there are a few issues with this latter study that limit the conclusions we can draw.
Firstly, the researchers measured muscle growth using something called a muscle biopsy, which involves taking a slice of muscle tissue from the body and looking at it under a microscope.
However, isolated tissue samples from an individual muscle give you a very limited picture about what's happening to muscle growth in the whole body. A better way to measure whole-body muscle growth would have been to use hydrostatic weighing, DEXA, or air displacement plethysmography (BOD-POD).
In addition, the training program involved 15-20 minutes of leg extensions three times a week... and that's it! Not the type of routine most people would use if they were trying to build size and strength.
An elderly muscle may respond very differently than a young muscle. We can't assume that the results will apply to younger people in their twenties, thirties and forties.
Finally, some elderly people may suffer from age-related aches and pains. The pain killers may have allowed them to train harder during each workout, which could have contributed to the extra gains in muscle size and strength.
The last study I want to look at comes from a group of Canadian researchers who examined the impact of a more moderate dose of ibuprofen (400 milligrams per day) on gains in muscle size and strength .
Twelve men and 6 women (approximately 24 years of age) trained their right and left biceps on alternate days (6 sets of 4-10 repetitions), 5 days a week for 6 weeks.
They received a daily dose of 400 milligrams of ibuprofen immediately after training their left or right arm, and a placebo after training the opposite arm the following day.
Muscle thickness of both biceps was measured using ultrasound and 1 repetition maximum (1-RM) arm curl strength was determined on both arms.
So did ibuprofen help or hinder muscle growth?
Biceps muscle thickness in the arm receiving ibuprofen went from 3.63 to 3.92 centimeters. That's an increase of 8%, which was no different to the placebo arm. Gains in muscle strength were also much the same in the ibuprofen and placebo groups, with both groups posting roughly a 20% average gain in arm curl strength.
To quote the researchers directly:
A moderate dose of ibuprofen ingested after repeated resistance training sessions does not impair muscle hypertrophy or strength and does not affect ratings of muscle soreness.
The explanation for ibuprofen's lack of effect, positive or negative, is most likely due to the dosage used. The earlier research by Professor Trappe used maximum over-the-counter doses (1200 milligrams of ibuprofen per day). This Canadian study used just one-third of that amount (400 milligrams per day).
Inflammation and injury
Quite apart from their impact on muscle growth, there are a couple of other downsides to anti-inflammatory pain killers (known as Non Steroidal Anti-Inflammatory Drugs, or NSAIDs).
Firstly, NSAIDs appear to have a negative impact on the health of your tendons, which connect muscle to bone. One study shows that NSAID use (oral 2 x 100 milligrams Indometacin daily for 7 days) abolished the adaptive increase in collagen synthesis in the patella tendon normally seen after exercise .
What this means is that if they're used for prolonged periods, NSAIDs could weaken connective tissue, increasing your risk of injury further down the line.
More interesting still, there is some animal research to show that the inflammation caused by an injury actually plays a vital role in healing damaged muscle tissue .
Researchers found that the presence of inflammatory cells (macrophages) in acute muscle injury produce a high level of a growth factor called insulin-like growth factor-1 (IGF-1) which increases the rate of muscle regeneration. The report shows that muscle inflammatory cells produce the highest levels of IGF-1, which improves muscle injury repair.
"For wounds to heal we need controlled inflammation, not too much, and not too little," says Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal, the journal in which the study was published.
"It's been known for a long time that excess anti-inflammatory medication, such as cortisone, slows wound healing. This study goes a long way to telling us why: insulin-like growth factor and other materials released by inflammatory cells helps wound to heal."
What's the bottom line?
The extent to which
the prolonged use of pain killers affects muscle growth over a
period of several weeks or months is open to debate. However, there is mounting evidence that high doses may extinguish the fire that sparks muscle growth after exercise.
While the occasional use of pain killers in moderate amounts isn't likely to suppress your gains completely, they're certainly not something you should use
too often. Large doses taken on a regular basis could easily add up to a negative impact on muscle growth in the long run.
If you enjoyed this post, there’s a good chance you’ll also like Truth and Lies about Building Muscle: 10 Muscle Myths Debunked By Science.
It's a FREE 20-page special report (PDF) I put together to debunk 10 popular myths that are still widely believed, despite all the evidence to the contrary. Click here now to download a copy.
About the Author
Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.
If you want better, faster results from the time you spend in the gym, click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.
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Lu H, Huang D, Saederup N, Charo IF, Ransohoff RM, Zhou L. (2010). Macrophages recruited via CCR2 produce insulin-like growth factor-1 to repair acute skeletal muscle injury. FASEB Journal