Skeletal muscle health has been shown to benefit from regular consumption of cyclooxygenase (COX) inhibiting drugs. Aspirin, especially at low doses, is one of the most commonly consumed COX inhibitors, yet investigations of low dose aspirin effects on skeletal muscle are nonexistent. The goal of this study was to examine the efficacy of low dose aspirin on skeletal muscle COX production of the inflammatory regulator prostaglandin (PG) E2 at rest and following exercise. Skeletal muscle biopsies (vastus lateralis) were taken from eight individuals (4M, 4W; 25±1y; 81.4±3.4kg; VO2max: 3.33±0.21L/min) before and 3.5 hours after 40 minutes of cycling at 70% of VO2max for the measurement of ex vivo PGE2 production. Muscle strips were incubated in Krebs-Henseleit buffer (control) or supplemented with one of two aspirin concentrations that reflected blood levels following a low (10µM; typical oral dose: 75-325mg) or standard (100µM; typical oral dose: 975-1000mg) dose. Low (-22±5%) and standard (-28±5%) dose aspirin concentrations both reduced skeletal muscle PGE2 production, independent of exercise (P<0.05). There was no difference in PGE2suppression between the two doses (P>0.05). In summary, low dose aspirin levels are sufficient to inhibit the COX enzyme in skeletal muscle and significantly reduce production of PGE2, a known regulator of skeletal muscle health. Aerobic exercise does not appear to alter the inhibitory efficacy of aspirin. These findings may have implications for the tens of millions of individuals that chronically consume low dose aspirin.

Prostaglandin (PG) E2 has been linked to increased inflammation and attenuated resistance exercise adaptations in skeletal muscle. Nonaspirin cyclooxygenase (COX) inhibitors have been shown to reduce these effects. This study examined the effect of low‐dose aspirin on skeletal muscle COX production of PGE2 at rest and following resistance exercise. Skeletal muscle (vastus lateralis) biopsies were taken from six individuals (4 M/2 W) before and 3.5 hr after a single bout of resistance exercise for ex vivo PGE2 production under control and low (10 μM)‐ or standard (100 μM)‐dose aspirin conditions. Sex‐specific effects of aspirin were also examined by combining the current findings with our previous similar ex vivo skeletal muscle investigations (n = 20, 10 M/10 W). Low‐dose aspirin inhibited skeletal muscle PGE2 production (p < 0.05). This inhibition was similar to standard‐dose aspirin (p > 0.05) and was not influenced by resistance exercise (p > 0.05) (overall effect: −18 ± 5%). Men and women had similar uninhibited skeletal muscle PGE2 production at rest (men: 1.97 ± 0.33, women: 1.96 ± 0.29 pg/mg wet weight/min; p > 0.05). However, skeletal muscle of men was 60% more sensitive to aspirin inhibition than women (p < 0.05). In summary, the current findings 1) confirm low‐dose aspirin inhibits the PGE2/COX pathway in human skeletal muscle, 2) show that resistance exercise does not alter aspirin inhibitory efficacy, and 3) suggest the skeletal muscle of men and women could respond differently to long‐term consumption of low‐dose aspirin, one of the most common chronically consumed drugs in the world.

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There is some evidence that the age-associated change in skeletal muscle mass is muscle specific, yet the number of specific muscles that have been studied to form our understanding in this area is limited. In addition, few aging investigations have examined multiple muscles in the same individuals. This longitudinal investigation compared changes in skeletal muscle size via computed tomography of the quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), hamstrings (biceps femoris short and long heads, semitendinosus, semimembranosus), psoas, rectus abdominis, lateral abdominals (obliques and transversus abdominis), and paraspinal muscles (erector spinae and multifidi) of older individuals from the Health ABC study at baseline and 5.0±0.1 years later (n=469, 73±3yr & 78±3yr, 49% women, 33% black). Skeletal muscle size decreased (p<0.05) in quadriceps (-3.3%), hamstrings (-5.9%), psoas (-0.4%), and rectus abdominis (-7.0%). The hamstrings and rectus abdominis atrophied approximately twice as much as the quadriceps (p<0.05), while the quadriceps atrophied substantially more than the psoas (p<0.05). The lateral abdominals (+5.9%) and paraspinals (+4.3%) hypertrophied (p<0.05) to a similar degree (p>0.05) over the 5 years. These data suggest that older individuals experience skeletal muscle atrophy and hypertrophy in a muscle group-specific fashion in the eighth decade, a critical time period in the aging process. A broader understanding of muscle group-specific skeletal muscle aging is needed to better guide exercise programs and other interventions that mitigate decrements in physical function with aging.

This investigation studied DNA, RNA, and protein contents of adipose and skeletal muscle tissues from young active individuals. A series of optimization steps were investigated to aid in determining the optimal approach to extract high-yield and high-quality biomolecules. These findings contribute to the knowledge gap in adipose tissue requirements for molecular biology assays, which is of increasing importance due to the growing interest in adipose tissue research involving human exercise physiology research.

We assessed the feasibility of the Molecular Transducers of Physical Activity Consortium (MoTrPAC) human adult clinical exercise protocols, while also documenting select cardiovascular, metabolic, and molecular responses to these protocols. After phenotyping and familiarization sessions, 20 subjects (25±2yr, 12M, 8W) completed an endurance exercise bout (n=8, 40 min cycling at 70% VO2max), a resistance exercise bout (n=6, ~45 min, 3 sets of ~10 repetition maximum, 8 exercises), or a resting control period (n=6, 40 min rest). Blood samples were taken before, during, and after (10 min, 2h, 3.5h) exercise or rest for levels of catecholamines, cortisol, glucagon, insulin, glucose, free fatty acids, and lactate. Heart rate was recorded throughout exercise (or rest). Skeletal muscle (vastus lateralis) and adipose (peri-umbilical) biopsies were taken before and ~4h following exercise or rest for mRNA levels of genes related to energy metabolism, growth, angiogenesis, and circadian processes. Coordination of the timing of procedural components (e.g., local anesthetic delivery, biopsy incisions, tumescent delivery, intravenous line flushes, sample collection and processing, exercise transitions, and team dynamics) were reasonable to orchestrate while considering subject burden and scientific objectives. The cardiovascular and metabolic alterations reflected a dynamic and unique response to endurance and resistance exercise, while skeletal muscle was transcriptionally more responsive than adipose 4h post-exercise. In summary, the current report provides the first evidence of protocol execution and feasibility of key components of the MoTrPAC human adult clinical exercise protocols. Scientists should consider designing exercise studies in various populations to interface with the MoTrPAC protocols and DataHub.

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