We have previously shown that muscle hypertrophy is enhanced (p<0.05) during 12 weeks of knee-extensor resistance training (3d/wk, 70% 1RM) in the elderly by daily consumption of ibuprofen or acetaminophen compared with placebo. PURPOSE: To examine if the muscle protein and water content, as well as the myosin heavy chain (MHC) distribution were influenced by the daily consumption of these over-the-counter cyclooxygenase inhibiting drugs during the resistance training. METHODS: Thirty-six individuals were randomly assigned to one of three groups and consumed the drugs in double-blind placebo-controlled fashion: Placebo (67±2 y; 8M, 4F), Ibuprofen (64±1 y; 9M, 4F; 1.2g/d), or Acetaminophen (64±1 y; 7M, 4F; 4g/d). Muscle biopsies were obtained from the vastus lateralis before and after the 12 week resistance training program. RESULTS: Resistance training alone (Placebo) did not influence (p>0.05) muscle protein (Pre: 150±3, Post: 156±3 μg/mg wet wt.) or water (Pre: 77±1 Post: 77±0.4%) content. Similarly, muscle protein and water content were unchanged (p>0.05) in the Ibuprofen (Pre: 151±2, Post: 154±3 μg/mg wet wt.; Pre: 78±0.3 Post: 77±0.3%) and Acetaminophen (Pre: 154±4, Post: 151±3 μg/mg wet wt.; Pre: 77±0.4 Post: 77±0.3%) groups. MHC distribution was not influenced (p>0.05) by drug consumption, but resistance training did alter (p<0.05) the amount of MHC IIa and IIx in the muscle (MHC I: Pre: 38±1, Post: 39±1%; MHC IIa: Pre: 30±1, Post: 33±1%; MHC IIx: Pre: 32±1, Post: 29±1%). CONCLUSION: These results suggest that the additional hypertrophy induced by chronic consumption of ibuprofen or acetaminophen during resistance training in the elderly does not result in disproportionate changes in the general muscle protein composition, water content, or distribution of the main motor protein myosin heavy chain. Supported by NIH R01 AG020532.

The aim of this study was to develop an approach to directly assess protein fractional synthesis rate (FSR) in isolated human muscle fibers in a fiber type-specific fashion. Individual muscle fibers were isolated from biopsies of the vastus lateralis (VL) and soleus (SOL) obtained from eight young men during a primed, continuous infusion of [5,5,5-(2)H3]leucine performed under basal conditions. To determine mixed protein FSR, a portion of each fiber was used to identify fiber type, fibers of the same type were pooled, and the [5,5,5-(2)H3]leucine enrichment was determined via GC-MS. Processing isolated slow-twitch [myosin heavy chain (MHC) I] and fast-twitch (MHC IIa) fibers for mixed protein bound [5,5,5-(2)H3]leucine enrichment yielded mass ion chromatographic peaks that were similar in shape, abundance, and measurement reliability as tissue homogenates. In the VL, MHC I fibers exhibited a 33% faster (P<0.05) mixed protein FSR compared with MHC IIa fibers (0.068+/-0.006 vs. 0.051+/-0.003%/h). MHC I fibers from the SOL (0.060+/-0.005%/h) and MHC I fibers from the VL displayed similar (P>0.05) mixed protein FSR. Feasibility of processing isolated human muscle fibers for analysis of myofibrillar protein [5,5,5-(2)H3]leucine enrichment was also confirmed in non-fiber-typed pooled fibers from the VL. These methods can be applied to the study of fiber type-specific responses in human skeletal muscle. The need for this level of investigation is underscored by the different contributions of each fiber type to whole muscle function and the numerous distinct adaptive functional and metabolic changes in MHC I and MHC II fibers originating from the same muscle.

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 ± 2 yr; n = 12), acetaminophen (64 ± 1 yr; n = 11; 4 g/day), and ibuprofen (64 ± 1 yr; n = 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 > 0.05) for all three groups. Drug consumption unexpectedly increased muscle volume (acetaminophen: 109 ± 14 cm(3), 12.5%; ibuprofen: 84 ± 10 cm(3), 10.9%) and muscle strength (acetaminophen: 19 ± 2 kg; ibuprofen: 19 ± 2 kg) to a greater extent (P < 0.05) than placebo (muscle volume: 69 ± 12 cm(3), 8.6%; muscle strength: 15 ± 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 > 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 > 0.05) by drug consumption, although resistance training did result in a drug-independent increase in COX-1 (32 ± 8%; P < 0.05). Drug consumption did not influence the size of the nonresistance-trained hamstring muscles (P > 0.05). Over-the-counter 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.

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.

Tendon is mainly composed of collagen and an aqueous matrix of proteoglycans that are regulated by enzymes called matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Although it is known that resistance exercise (RE) and sex influence tendon metabolism and mechanical properties, it is uncertain what structural and regulatory components contribute to these responses. We measured the mRNA expression of tendon's main fibrillar collagens (type I and type III) and the main proteoglycans (decorin, biglycan, fibromodulin, and versican) and the regulatory enzymes MMP-2, MMP-9, MMP-3, and TIMP-1 at rest and after RE. Patellar tendon biopsy samples were taken from six individuals (3 men and 3 women) before and 4 h after a bout of RE and from a another six individuals (3 men and 3 women) before and 24 h after RE. Resting mRNA expression was used for sex comparisons (6 men and 6 women). Collagen type I, collagen type III, and MMP-2 were downregulated (P < 0.05) 4 h after RE but were unchanged (P > 0.05) 24 h after RE. All other genes remained unchanged (P > 0.05) after RE. Women had higher resting mRNA expression (P < 0.05) of collagen type III and a trend (P = 0.08) toward lower resting expression of MMP-3 than men. All other genes were not influenced (P > 0.05) by sex. Acute RE appears to stimulate a change in collagen type I, collagen type III, and MMP-2 gene regulation in the human patellar tendon. Sex influences the structural and regulatory mRNA expression of tendon.

The tendon is mainly composed of collagen surrounded by a matrix of proteoglycans that are regulated by enzymes called matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Studies have shown that acute exercise stimulates collagen turnover, but little is known about the influence exercise has on other components of the tendon. Therefore, we measured the gene expression (mRNA) levels of the tendon's main proteins (collagen type I and collagen type III), proteoglycans (decorin, biglycan, fibromodulin, and versican), and regulatory enzymes (MMP‐2, MMP‐9, MMP‐3, and TIMP‐1) at rest and following resistance exercise (RE). Patellar tendon biopsy samples were taken from six individuals (3M, 3F) before and 4h following a bout of RE (3 sets of 10 repetitions at ~70% of 1RM) and from a separate six individuals (3M, 3F) before and 24h following RE and analyzed using real‐time RT‐PCR. Collagen type I, collagen type III, and MMP‐2 mRNA levels were downregulated (p<0.05) 4h following RE, but were unchanged 24h following RE (p>0.05). The other target mRNAs remained unchanged (p>0.05) following RE. Based on these gene expression results, we speculate that acute resistance exercise stimulates both collagen type I and type III turnover in the human patellar tendon. In addition, the proteoglycans appear to be relatively refractory to a resistance exercise stimulus.NIH R01 AG020532 (TT)