Browsing by Subject "Milk -- Physiological effect."
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Item Effects of four weeks of daily soy milk or dairy milk ingestion on the exercise induced inflammatory and oxidative responses in plasma and skeletal muscle in a post-menopausal female population.(2009-08-24T20:26:23Z) Beavers, Kristen Marie.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.The process of senescence is associated with increasing inflammation and subsequent oxidative stress in the body, both of which can exert negative health effects at local and systemic levels. Attenuation of such processes with novel dietary countermeasures has major public health implications. Soyfoods, as a source of high quality protein, minimal saturated fat, and unique composition of isoflavones may improve such indices, although such effects in healthy older women are not well delineated. To explore this supposition, a single-blind, randomized, controlled trial was conducted on 31 postmenopausal women at Baylor University, Waco TX. After a two week run-in period, subjects were randomly assigned to consume three servings of vanilla soy (n=16) or reduced-fat dairy (n=15) milk per day for four weeks. Parameters of systemic inflammation (TNF-α, IL-1β, IL-6) and oxidative stress (SOD, GPx, COX-2) as well as expression of local inflammation-responsive genes (TNF-α, IL-1β, IL-6, COX-2, NF-κB) were measured prior to supplementation, at four weeks post supplementation, and after an eccentric exercise bout performed to elicit an inflammatory response. A significant group by time effect for plasma TNF-α was observed (p = 0.04), with TNF-α values for the soy group appearing to stay consistent during the exercise period, while the TNF-α values for the dairy group increased post-supplementation, decreased from T2-T4, and then returned to baseline by T6. Significant time effects were observed for plasma SOD (p < 0.0001) and IL-6 (p < 0.0001), and muscle expression of IL-6 (p < 0.01) and IL-1β (p<0.01). Despite good dietary compliance, overall results from our study do not support the notion that four weeks of daily soy milk ingestion can attenuate systemic or local elevations in markers of oxidative stress or inflammation. However, data do suggest that the downhill running protocol utilized in this study can be effective at altering systemic and local markers of inflammation, and that ingestion of soy may help to maintain plasma TNF-α levels even when exposed to a stress inducing stimulus, although more data exploring this conjecture is certainly warranted.Item Effects of four weeks of daily soy or dairy milk ingestion on the exercise-induced proteolytic responses in plasma and skeletal muscle in a post-menopausal female population.(2009-08-25T16:30:08Z) Serra, Monica Christine.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Sarcopenia is defined as a loss of muscle mass and muscle strength associated with aging. Changes in muscle function can occur as early as the fourth decade of life. Evidence indicates that the calpain and ubiquitin proteolytic degradation pathways account for the majority of myofibrillar protein degradation seen with muscle atrophy. The purpose of this study was to investigate the effects of daily consumption of soy or dairy milk in older females on systemic plasma and local skeletal muscle markers of muscle proteolysis before and after a single bout of eccentric exercise. Thirty one female participants consumed three servings per day of either soy or dairy milk for four weeks, followed by a 45 minute downhill run. Testing sessions were complete pre and post supplementation, as well as at 0, 4, 24, and 48 hrs post exercise. Each testing session included blood collection and vastus lateralis muscle biopsy, except no biopsy was performed immediately or 48 hrs post exercise. The blood was analyzed for plasma creatine kinase and the muscle tissue for mRNA expression of ubiquitin, E2, E3, atrogin-1, muRF1, calpain 1, and calpain 2. Although no significant group x time interactions were observed, a significant time effect was observed for plasma CK (p<0.0001) and muscle mRNA expression of E3 (p=0.04), atrogin-1 (p=0.02), and calpain 2 (p=0.04). Further, evaluation revealed that these differences resulted after the acute exercise bout. The results of this study showed that soy milk ingestion was not influential in attenuating the expression of the ubiquitin and calpain proteolytic pathways compared to dairy milk; however, the eccentric exercise bout was effective at altering expression of markers within both pathways. Future studies should address potential confounding dietary factors by utilizing an inert control group to determine if both soy and dairy milk could be protective with regard to exercise induced proteolysis.