Trappe TA, Carroll CC, Dickinson JM, LeMoine JK, Haus JM, Sullivan BE, Lee JD, Jemiolo B, Weinheimer EM, Hollon CJ. Influence of acetaminophen and ibuprofen on skeletal muscle adaptations to resistance exercise in older adults. Am J Physiol Regul Integr Comp Physiol 300: R655-R662, 2011. First published December 15, 2010; doi:10.1152/ajpregu.00611.2010.-Evidence suggests that consumption of over-the-counter cyclooxygenase (COX) inhibitors may interfere with the positive effects that resistance exercise training has on reversing sarcopenia in older adults. This study examined the influence of acetaminophen or ibuprofen consumption on muscle mass and strength during 12 wk of knee extensor progressive resistance exercise training in older adults. Thirty-six individuals were randomly assigned to one of three groups and consumed the COX-inhibiting drugs in double-blind placebo-controlled fashion: placebo (67 Ϯ 2 yr; n ϭ 12), acetaminophen (64 Ϯ 1 yr; n ϭ 11; 4 g/day), and ibuprofen (64 Ϯ 1 yr; n ϭ 13; 1.2 g/day). Compliance with the resistance training program (100%) and drug consumption (via digital video observation, 94%), and resistance training intensity were similar (P Ͼ 0.05) for all three groups. Drug consumption unexpectedly increased muscle volume (acetaminophen: 109 Ϯ 14 cm 3 , 12.5%; ibuprofen: 84 Ϯ 10 cm 3 , 10.9%) and muscle strength (acetaminophen: 19 Ϯ 2 kg; ibuprofen: 19 Ϯ 2 kg) to a greater extent (P Ͻ 0.05) than placebo (muscle volume: 69 Ϯ 12 cm 3 , 8.6%; muscle strength: 15 Ϯ 2 kg), when controlling for initial muscle size and strength. Follow-up analysis of muscle biopsies taken from the vastus lateralis before and after training showed muscle protein content, muscle water content, and myosin heavy chain distribution were not influenced (P Ͼ 0.05) by drug consumption. Similarly, muscle content of the two known enzymes potentially targeted by the drugs, COX-1 and -2, was not influenced (P Ͼ 0.05) by drug consumption, although resistance training did result in a drug-independent increase in COX-1 (32 Ϯ 8%; P Ͻ 0.05). Drug consumption did not influence the size of the nonresistance-trained hamstring muscles (P Ͼ 0.05). Over-thecounter doses of acetaminophen or ibuprofen, when consumed in combination with resistance training, do not inhibit and appear to enhance muscle hypertrophy and strength gains in older adults. The present findings coupled with previous short-term exercise studies provide convincing evidence that the COX pathway(s) are involved in the regulation of muscle protein turnover and muscle mass in humans.cyclooxygenase; prostaglandin; sarcopenia SARCOPENIA, DEFINED AS THE loss of skeletal muscle mass, is a debilitating clinical condition associated with old age (13,40). This age-related loss of muscle mass is associated with a loss of muscle strength and function, a reduced functional independence, and a financial burden to the US healthcare system estimated at $20 billion per year (19,23,24,51). One of the most proven treatments for sarcopenia is resistance exercise training, which in...

Millions of older individuals consume acetaminophen or ibuprofen daily and these same individuals are encouraged to participate in resistance training. Several in vitro studies suggest that cyclooxygenase-inhibiting drugs can alter tendon metabolism and may influence adaptations to resistance training. Thirty-six individuals were randomly assigned to a placebo (67 ± 2 yr old), acetaminophen (64 ± 1 yr old; 4,000 mg/day), or ibuprofen (64 ± 1 yr old; 1,200 mg/day) group in a double-blind manner and completed 12 wk of knee extensor resistance training. Before and after training in vivo patellar tendon properties were assessed with MRI [cross-sectional area (CSA) and signal intensity] and ultrasonography of patellar tendon deformation coupled with force measurements to obtain stiffness, modulus, stress, and strain. Mean patellar tendon CSA was unchanged (P > 0.05) with training in the placebo group, and this response was not influenced with ibuprofen consumption. Mean tendon CSA increased with training in the acetaminophen group (3%, P < 0.05), primarily due to increases in the mid (7%, P < 0.05) and distal (8%, P < 0.05) tendon regions. Correspondingly, tendon signal intensity increased with training in the acetaminophen group at the mid (13%, P < 0.05) and distal (15%, P = 0.07) regions. When normalized to pretraining force levels, patellar tendon deformation and strain decreased 11% (P < 0.05) and stiffness, modulus, and stress were unchanged (P > 0.05) with training in the placebo group. These responses were generally uninfluenced by ibuprofen consumption. In the acetaminophen group, tendon deformation and strain increased 20% (P < 0.05) and stiffness (-17%, P < 0.05) and modulus (-20%, P < 0.05) decreased with training. These data suggest that 3 mo of knee extensor resistance training in older adults induces modest changes in the mechanical properties of the patellar tendon. Over-the-counter doses of acetaminophen, but not ibuprofen, have a strong influence on tendon mechanical and material property adaptations to resistance training. These findings add to a growing body of evidence that acetaminophen has profound effects on peripheral tissues in humans.

We have shown that ibuprofen and acetaminophen block cyclooxygenase (COX) synthesis of prostaglandin PGF(2alpha) and the muscle protein synthesis increase following resistance exercise. Confusingly, these two drugs are purported to work through different mechanisms, with acetaminophen apparently unable to block COX and ibuprofen able to nonspecifically block COX-1 and COX-2. A recently discovered intron-retaining COX, now known to have three variants, has been shown to be sensitive to both drugs. We measured the expression patterns and levels of the intron 1-retaining COX-1 variants (-1b1, -1b2, and -1b3), COX-1, and COX-2 at rest and following resistance exercise to help elucidate the COX through which PGF(2alpha), ibuprofen, and acetaminophen regulate muscle protein synthesis. Skeletal muscle biopsy samples were taken from 16 individuals (8M, 8F) before, 4, and 24 h after a bout of resistance exercise and analyzed using real-time RT-PCR. Relatively few individuals expressed the intron 1-retaining COX-1b variants (COX-1b1, -1b2, and -1b3) at any time point, and when expressed, these variants were in very low abundance. COX-1 was the most abundant COX mRNA before exercise and remained unchanged (P > 0.05) following exercise. COX-2 was not expressed before exercise, but increased significantly (P < 0.05) at 4 and 24 h after exercise. The inconsistent and low levels of expression of the intron 1-retaining COX-1 variants suggest that these variants are not likely responsible for the inhibition of PGF(2alpha) production and skeletal muscle protein synthesis after resistance exercise by ibuprofen and acetaminophen. Skeletal muscle-specific inhibition of COX-1 or COX-2 by these drugs should be considered.

Nonselective blockade of the cyclooxygenase (COX) enzymes in skeletal muscle eliminates the normal increase in muscle protein synthesis following resistance exercise. The current study tested the hypothesis that this COX-mediated increase in postexercise muscle protein synthesis is regulated specifically by the COX-2 isoform. Sixteen males (23 +/- 1 yr) were randomly assigned to one of two groups that received three doses of either a selective COX-2 inhibitor (celecoxib; 200 mg/dose, 600 mg total) or a placebo in double-blind fashion during the 24 h following a single bout of knee extensor resistance exercise. At rest and 24 h postexercise, skeletal muscle protein fractional synthesis rate (FSR) was measured using a primed constant infusion of [(2)H(5)]phenylalanine coupled with muscle biopsies of the vastus lateralis, and measurements were made of mRNA and protein expression of COX-1 and COX-2. Mixed muscle protein FSR in response to exercise (P < 0.05) was not suppressed by the COX-2 inhibitor (0.056 +/- 0.004 to 0.108 +/- 0.014%/h) compared with placebo (0.074 +/- 0.004 to 0.091 +/- 0.005%/h), nor was there any difference (P > 0.05) between the placebo and COX-2 inhibitor postexercise when controlling for resting FSR. The COX-2 inhibitor did not influence COX-1 mRNA, COX-1 protein, or COX-2 protein levels, whereas it did increase (P < 0.05) COX-2 mRNA (3.0 +/- 0.9-fold) compared with placebo (1.3 +/- 0.3-fold). It appears that the elimination of the postexercise muscle protein synthesis response by nonselective COX inhibitors is not solely due to COX-2 isoform blockade. Furthermore, the current data suggest that the COX-1 enzyme is likely the main isoform responsible for the COX-mediated increase in muscle protein synthesis following resistance exercise in humans.

Almost no data exist regarding skeletal muscle responses to real or simulated spaceflight in women. We determined the impact of 60-day bedrest (BR, n=8), 60-day bedrest with exercise-training (BRE, n=8), and 60-day bedrest with a leucine-enriched, high-protein diet (BRN, n=8) on muscle protein composition. Vastus lateralis and soleus muscle biopsies were analyzed for global protein fractions (mixed, sarcoplasmic, myofibrillar) and force-specific proteins (myosin, actin, collagen). Concentrations (micrograms per milligram muscle wet weight) of these proteins were maintained (P>0.05) in BR, despite large changes in quadriceps (-21%) and triceps surae (-29%) volume. Neither countermeasure influenced muscle protein content in either muscle (P>0.05), despite exacerbation (BRN) or prevention (BRE) of atrophy. Pre-bedrest comparisons showed less myofibrillar protein in the soleus (-16%, P<0.05), primarily due to less myosin (-12%, P<0.05) and more collagen (234%, P<0.05) than the vastus lateralis. Muscle protein composition is tightly regulated in lower limb muscles of women, despite the most extreme weightlessness-induced atrophy reported in humans. In contrast, men who underwent prolonged unloading were unable to proportionally regulate atrophy of the soleus. These findings have implications for astronauts and clinical conditions of sarcopenia regarding the maintenance of muscle function and prevention of frailty.

LeMoine JK, Lee JD, Trappe TA. Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking. Am J Physiol Regul Integr Comp Physiol 296: R119 -R124, 2009. First published October 22, 2008 doi:10.1152/ajpregu.90607.2008.-Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. Sex and chronic resistance training have been shown to alter tendon function and may also alter the key structural features of tendon. Patellar tendon biopsies were taken from untrained men [n ϭ 8, 1 repetition maximum (RM) ϭ 53 Ϯ 3 kg], untrained women (n ϭ 8, 1 RM ϭ 29 Ϯ 2 kg), and resistance-trained (10 Ϯ 1 yr of training) men (n ϭ 8, 1 RM ϭ 71 Ϯ 6 kg). Biopsies were analyzed for dry mass, collagen content, and collagen cross-linking (hydroxylysylpyridinoline). We hypothesized that these elements of tendon structure would be lower in women than men, whereas chronic resistance training would increase these parameters in men. Tendon dry mass was significantly lower in women than men (343 Ϯ 5 vs. 376 Ϯ 8 g dry mass/mg tendon wet wt, P Ͻ 0.01) and was not influenced by chronic resistance training (P Ͼ 0.05). The lower tendon dry mass in women tended to reduce (P ϭ 0.08) collagen content per tendon wet weight. Collagen content of the tendon dry mass was not influenced by sex or resistance training (P Ͼ 0.05). Similarly, cross-linking of collagen was unaltered (P Ͼ 0.05) by sex or training. Although sex alters the water content of patellar tendon tissue, any changes in tendon function with sex or chronic resistance training in men do not appear to be explained by alterations in collagen content or cross-linking of collagen within the dry mass component of the tendon. human tendon; water content; hydroxyproline; hydroxylysylpyridinoline TENDONS ARE THE FIBROELASTIC structures that connect muscle to bone and convey muscular force (5,22,23). The tensile strength of tendon tissue is estimated to be 50 -100 N/mm 2 (5), a key feature as tendons are subjected daily to high forces. The composition of tendon tissue influences its strength and integrity, playing a key role in force transmission through the muscle-tendon complex (23). Animal and human cadaver studies indicate that tendon tissue is ϳ55-70% water (5, 23), with the remaining dry mass containing the extracellular matrix and tendon cells (5,22). Collagen is the main protein component of tendon tissue, comprising ϳ65-75% of the dry mass (5,22,23). Collagen molecules are joined into fibrils and fibers by lysine-based cross-links [hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP)] (7,22,23,30). Tendon dry mass, collagen content, and cross-links have been shown to impact tendon strength and mechanical properties (22,23,30,52).Tendon tissue is dynamic, highly metabolic, and quite responsive to exercise (23,24,29,34). Tendons should therefore adapt in a positive manner to long-term loading, becoming more damage resistant and ensuring optimal muscular force transmissi...

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