Browsing by Subject "Skeletal muscle damage"

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Characterization of insulin-like growth factor-I gene expression and post-receptor signaling in skeletal muscle following tourniquet-induced ischemia reperfusion injury in young and old mice
(2007-12) Hammers, David Wayne; Farrar, Roger P.
Pneumatic tourniquet (TK) use is common during orthopedic surgery, making postoperative recovery from ischemia-reperfusion injury (I/R) a considerable affliction to the elderly. To characterize age-related mechanisms in skeletal muscle I/R recovery, 6- month (young) and 24-month-old (old) C57 B/L mice underwent 2 hours of TK-induced ischemia, followed by 1, 3, 5, or 7 days of recovery. More damage and muscle mass loss was seen in old in response to the I/R injury than young. Old subjects demonstrate both reductions and temporal shifts in total IGF-I, IGF-I Ea, and IGF-I Eb gene expression in the first 7 days compared to the young. Old subjects also show significant reductions in Akt-dependent pro-anabolic signaling (mTOR and FoxO3) through the time course, but were more pronounced at day 7. These data demonstrate that aged skeletal muscle is characterized by more damage and impaired recovery following TK-induced I/R damage, and link the significantly blunted IGF-I expression and signaling during the early course of recovery to this phenomenon.
Effect of hydroxytyrosol supplementation on muscle damage in healthy human following an acute bout of exercise
(2013-05) Kim, Heon Tae; Farrar, Roger P.; Ivy, John, 1945-
The purpose of this study was to investigate the effects of 6 weeks of hydroxytyrosol (HT) supplementation on markers of muscle damage in healthy, recreationally active men before and throughout acute aerobic exercise bouts. Using a randomized, double-blind, repeated-measures, placebo-controlled design, sixty-one (n = 61) subjects (21.46 ± 0.22 yrs, 179.46 ± 0.79 cm, 78.91 ± 1.19 kg) consumed either a high dose (HI) HT supplement (150 mg HT), a low dose (LO) HT supplement (50 mg HT), or a placebo (PLA) every day for 6 weeks. Throughout the course of the study, the subjects performed four time trial rides (TT1-TT4) on a cycle ergometer. TT1 occurred before supplementation, TT2 halfway through the supplementation period, and TT3 and TT4 occurred in the sixth week and final two days of supplementation. Blood was drawn prior to (pre) and just before termination (end) of each time trial to measure markers of muscle damage during exercise. We observed that endurance exercise increased indicators of muscle damage, CPK and myoglobin, but an association between HT treatment and reduced muscle damage indicators during exercise were not demonstrated. However, the HT supplementation for 6 weeks in recreationally-active males improved time trial performance in the HT treatment groups over the course of the study and this improvement was accompanied by a lower increase in myoglobin concentration in blood in the HI treatment group than in the LO treatment group. Also, performance was improved after 6 weeks in the PLA group. This improvement was associated with an increase in rating of perceived exertion (RPE). RPE was not increased in either the LO and HI treatment groups, although time trial performance was significantly improved. It is possible that HT can improve performance by altering perception of effort. We conclude that chronic and acute HT supplementation did not reduce markers of muscle damage in this population at rest, during, or following exercise, but improved aerobic performance.