OBJECTIVEThe contribution of mitochondrial dysfunction to skeletal muscle insulin resistance remains elusive. Comparative proteomics are being applied to generate new hypotheses in human biology and were applied here to isolated mitochondria to identify novel changes in mitochondrial protein abundance present in insulin-resistant muscle.RESEARCH DESIGN AND METHODSMitochondria were isolated from vastus lateralis muscle from lean and insulin-sensitive individuals and from obese and insulin-resistant individuals who were otherwise healthy. Respiration and reactive oxygen species (ROS) production rates were measured in vitro. Relative abundances of proteins detected by mass spectrometry were determined using a normalized spectral abundance factor method.RESULTSNADH- and FADH2-linked maximal respiration rates were similar between lean and obese individuals. Rates of pyruvate and palmitoyl-dl-carnitine (both including malate) ROS production were significantly higher in obesity. Mitochondria from obese individuals maintained higher (more negative) extramitochondrial ATP free energy at low metabolic flux, suggesting that stronger mitochondrial thermodynamic driving forces may underlie the higher ROS production. Tandem mass spectrometry identified protein abundance differences per mitochondrial mass in insulin resistance, including lower abundance of complex I subunits and enzymes involved in the oxidation of branched-chain amino acids (BCAA) and fatty acids (e.g., carnitine palmitoyltransferase 1B).CONCLUSIONSWe provide data suggesting normal oxidative capacity of mitochondria in insulin-resistant skeletal muscle in parallel with high rates of ROS production. Furthermore, we show specific abundance differences in proteins involved in fat and BCAA oxidation that might contribute to the accumulation of lipid and BCAA frequently associated with the pathogenesis of insulin resistance.
Objective Platelet‐rich plasma (PRP) has been increasingly studied as a treatment for tendinopathy. Many factors may influence outcomes after PRP, including different protocols following administration. It was hypothesized that there would be heterogeneity in post‐PRP protocols. Literature Survey A systematized review of the literature on post‐PRP protocols for tendinopathy was conducted using an electronic search of MEDLINE and Embase databases through September 2018. Methodology After duplicates were removed, English language articles involving adult patients who received PRP for tendinopathy were reviewed. Exclusion criteria included studies with fewer than 10 patients, PRP used to treat pathology other than tendinopathy, multiple protocols in one study, and surgical settings. Protocol specifics were extracted including nonsteroidal anti‐inflammatory drugs (NSAID) restrictions before and after injection, postinjection restrictions on movement and weight bearing, use of orthoses, activity modifications, and postinjection rehabilitation protocols. Given limitations in the data, a meta‐analysis was not performed. Synthesis Eighty‐four studies met inclusion criteria. Following PRP injection, weight‐bearing restrictions were mentioned rarely (12% of protocols). Orthosis use was uncommon overall (18%) but more common in Achilles tendinopathy protocols (53%). The majority of protocols instituted a period of stretching (51%) and strengthening (54%). Stretching programs generally began 2‐7 days following injection, and strengthening programs began within 2‐3 weeks. Preinjection NSAID restriction was reported rarely (20%), whereas postinjection NSAID restriction was more common (56%), with a typical restriction of greater than 2 weeks (38%). Return to play or full activity was reported in 42% of protocols, most commonly at 4‐6 weeks following injection. Conclusion Although the clinical effectiveness of PRP remains controversial, even less is known about the effect of post‐PRP protocols, which may affect the outcomes attributed to PRP itself. No studies directly compare post‐PRP protocols, and the protocols studied demonstrate substantial heterogeneity. Some consensus regarding post‐PRP protocols exists, although the rationale for these recommendations is limited.
Musculoskeletal ultrasound (US) has many applications in the care of athletes. This article reviews the current literature and identifies research gaps regarding musculoskeletal US in the athletic training room setting to evaluate and manage soccer players. The best evidence for US in the training room setting is for diagnosis and prognosis of muscle injuries, where studies show that it is equivalent to other imaging modalities. US also has been used for injury risk prediction, although the data are mixed. Many applications of US are described in other sport settings and may have crossover applications to soccer.
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