Ibuprofen cost young lifters muscle and gained older ones some
Over eight weeks, 18 to 35 year olds on 1,200 mg a day gained 3.7% quadriceps volume against 7.5% on aspirin. Adults aged 64 to 67 gained 10.9% against 8.6%.
What the study found
Ibuprofen halved muscle growth in young adults and raised it in old
Over eight weeks of knee-extensor training, 18 to 35 year olds on 1,200 mg of ibuprofen a day gained 3.7% quadriceps volume against 7.5% on low-dose aspirin. Given the same daily dose over twelve weeks, adults aged 64 to 67 gained 10.9% against 8.6% on placebo.
The caveat · Comparators and training differed
Thirty-one people in one trial and thirty-six in the other, one muscle group each. The comparators were not the same: the younger trial used low-dose aspirin rather than a true placebo, so it set a high dose against a low one rather than a drug against nothing. The training protocols and durations differed too, eight weeks against twelve. The older trial's authors state the direction was the opposite of what they expected.
What we don't know
Ibuprofen during strength training roughly halved muscle growth in young adults and added to it in older ones. Age, comparator, training and programme length all differed, so what flips the effect is unknown.