The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978, and the past three decades have resulted in a large growth of knowledge regarding exercise and oxidative stress. Although the sources of oxidant production during exercise continue to be debated, it is now well established that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. Importantly, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Furthermore, oxidants can modulate a number of cell signaling pathways and regulate the expression of multiple genes in eukaryotic cells. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, DNA repair proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue. Ongoing research continues to probe the mechanisms by which oxidants influence skeletal muscle contractile properties and to explore interventions capable of protecting muscle from oxidant-mediated dysfunction.

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Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production

Reactive oxygen species

Resistance exercise has been shown to elicit a significant acute hormonal response. It appears that this acute response is more critical to tissue growth and remodelling than chronic changes in resting hormonal concentrations, as many studies have not shown a significant change during resistance training despite increases in muscle strength and hypertrophy. Anabolic hormones such as testosterone and the superfamily of growth hormones (GH) have been shown to be elevated during 15-30 minutes of post-resistance exercise providing an adequate stimulus is present. Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth. Insulin is regulated by blood glucose and amino acid levels. However, circulating IGF-1 elevations have been reported following resistance exercise presumably in response to GH-stimulated hepatic secretion. Recent evidence indicates that muscle isoforms of IGF-1 may play a substantial role in tissue remodelling via up-regulation by mechanical signalling (i.e. increased gene expression resulting from stretch and tension to the muscle cytoskeleton leading to greater protein synthesis rates). Acute elevations in catecholamines are critical to optimal force production and energy liberation during resistance exercise. More recent research has shown the importance of acute hormonal elevations and mechanical stimuli for subsequent up- and down-regulation of cytoplasmic steroid receptors needed to mediate the hormonal effects. Other factors such as nutrition, overtraining, detraining and circadian patterns of hormone secretion are critical to examining the hormonal responses and adaptations to resistance training.

Hormonal Responses and Adaptations to Resistance Exercise and Training

In vitro and some animal models have shown that quercetin, a polyphenol derived from plants, has a wide range of biological actions including anti-carcinogenic, anti-inflammatory and antiviral activities; as well as attenuating lipid peroxidation, platelet aggregation and capillary permeability. This review focuses on the physicochemical properties, dietary sources, absorption, bioavailability and metabolism of quercetin, especially main effects of quercetin on inflammation and immune function. According to the results obtained both in vitro and in vivo, good perspectives have been opened for quercetin. Nevertheless, further studies are needed to better characterize the mechanisms of action underlying the beneficial effects of quercetin on inflammation and immunity.

Quercetin, Inflammation and Immunity

Nrf2-Keap1 signaling in oxidative and reductive stress.

The collection of exhaled breath condensate (EBC) is a non-invasive method for obtaining biosamples from the lower respiratory tract, an approach amenable to exercise, environmental, and work physiology applications. The purpose of this study was to develop a cost-effective, reproducible methodology for obtaining larger volume EBC samples. Participants (male: n = 10; female: n = 6; 26 ± 8 yrs.) completed a 10 min EBC collection using a novel device (N-EBC). After initial collection, a 45 min bout of cycling at 75% HRmax was performed, followed by another N-EBC collection. In a subset of individuals (n = 5), EBC was obtained using both the novel technique and a commercially available EBC collection device (R-EBC) in a randomized fashion. N-EBC volume—pre- and post-exercise (2.3 ± 0.8 and 2.6 ± 0.9 mL, respectively)—and pH (7.4 ± 0.5 and 7.4 ± 0.5, respectively) were not significantly different. When normalized for participant body height, device comparisons indicated N-EBC volumes were larger than R-EBC at pre-exercise (+12%) and post-exercise (+48%). Following moderate-intensity exercise, no changes in the pre- and post-trial values of Pentraxin 3 (0.25 ± 0.04 and 0.26 ± 0.06 pg/mL, respectively) and 8-Isoprostrane (0.43 ± 0.33 and 0.36 ± 0.24 pg/mL, respectively) concentrations were observed. In a cost-efficient fashion, the N-EBC method produced larger sample volumes, both pre- and post-exercise, facilitating more biomarker tests to be performed.

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Application of a Novel Collection of Exhaled Breath Condensate to Exercise Settings

1657 Board #310 June 2, 9:00 AM 10:30 AM Experimental Woodsmoke Exposure During Exercise and Blood Oxidative Stress Matthew Romero, Bridget Peters, Christopher Ballmann, Tiffany Quindry, Emily Gambrell, Justin McCroskey, Matthew Ferguson, Tony Ward, Charles Dumke, FACSM, John C. Quindry, FACSM. Auburn University, Auburn, AL. University of Montana, Missoula, MT. (Sponsor: John Quindry, FACSM) Email: mzr0049@tigermail.auburn.edu

Experimental Woodsmoke Exposure During Exercise and Blood Oxidative Stress: 1657 Board #310 June 2, 9: 00 AM - 10: 30 AM.

We tested the hypothesis that chronic testosterone treatment would promote a cardioprotective phenotype against ischemia/reperfusion (I/R) injury. For this study, 3-month-old F344 male rats underwent sham-surgery, orchiectomy (ORX), or ORX plus 21 days testosterone treatment (1.0 mg testosterone/day). At sacrifice, cardiac performance was assessed in a working heart model of I/R (25 min of global ischemia and 45 min of reperfusion). ORX reduced serum testosterone by approximately 98% and testosterone administration elevated serum testosterone to a concentration of 4.6-fold over that of Sham-operated controls (p<0.05). ORX did not significantly impair recovery of cardiac performance following I/R, but did increase cardiac release of lactate dehydrogenase (LDH) during pre- and post-ischemia (p<0.05). Testosterone administration prevented the ORX-induced increase in LDH during both pre- and post-ischemia and increased post-ischemic recovery of aortic flow, cardiac output, cardiac work, left ventricular developed pressure, and contractility (p<0.05) during reperfusion. Testosterone administration also increased left ventricular expression of catalase, but did not affect the expression of manganese superoxide dismutase, glutathione peroxidase, or sarcolemmal K (ATP) channel protein Kir6.2. Neither circulating nor cardiac concentrations of estradiol were altered by either treatment. We conclude that administration of high-dose testosterone confers cardioprotection through yet to be identified androgen-dependent mechanism(s).

John C. Quindry

Papers

Application of a Novel Collection of Exhaled Breath Condensate to Exercise Settings

Experimental Woodsmoke Exposure During Exercise and Blood Oxidative Stress: 1657 Board #310 June 2, 9: 00 AM - 10: 30 AM.

Testosterone administration induces protection against global myocardial ischemia

Quercetin effect on Mitochondrial Capacity and Cycling Efficiency: 907

Dietary quercetin enrichment improves respiratory function in mdx mice (884.17)