Scholarly Work - Health & Human Development

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Diurnal Variation, Response to Eccentric Exercise, and Association of Inflammatory Mediators with Muscle Damage Variables
(American Physiological Society, 2008) Miles, Mary; Andring, J.M.; Pearson, Sherri Diane; Gordon, L.K.; Kasper, C.; Depner, Chris M.; Kidd, J.R.
This investigation determined whether inflammatory mediators 1) have diurnal variations, 2) respond to high-force eccentric exercise, and 3) associate with markers of muscle damage after high-force eccentric exercise. College-aged men and women (n 51) completed exercise (3 15 maximal eccentric elbow flexor actions using 1 arm) and control conditions in random order. Blood was collected preexercise and 4, 8, 12, 24, 48, and 96 h postexercise. Additional measures included maximal isometric force and midbiceps arm circumference (to detect swelling). Serum and plasma were analyzed for soluble tumor necrosis factor receptor-1 (sTNFR1), IL-6, C-reactive protein, cortisol, and creatine kinase (CK) activity. Relative to the 7:00 AM point in the control condition, diurnal decreases were measured at 12:00 PM and 4:00 PM for IL-6 and at 12:00 PM, 4:00 PM, and 8:00 PM for sTNFR1 and cortisol. sTNFR1, IL-6, CK, swelling, and soreness were higher in the exercise compared with the control condition. The largest of the inflammatory mediator responses was measured for IL-6 8 h postexercise in the exercise (3.00 3.59 pg/ml) relative to the control condition (1.15 0.99 pg/ml). The IL-6 response (time-matched exercise control concentration) at 8 h associated (r 0.282) with muscle soreness at 24 and 96 h, and the cortisol response at 8 h associated (r 0.285) with swelling at 8, 24, and 96 h. Thus soreness and swelling, but not CK and strength loss, had a low association with the inflammatory response following eccentric exercise.
Effect of Carbohydrate Intake During Recovery from Eccentric Exercise on Interleukin-6 and Muscle Damage Markers
(Human Kinetics, 2007) Miles, Mary; Pearson, Sherri Diane; Andring, J.M.; Kidd, J.R.; Volpe, S.L.
The purpose of this investigation was to determine whether carbohydrate supplementation during the first 2 d postexercise recovery influenced the inflammation (IL-6, C-reactive protein [CRP], and cortisol) and muscle-damage responses. Eight participants performed a high-force eccentric elbow-flexion exercise to induce muscle soreness and inflammation and then consumed carbohydrate (0.25 g·kg–1·h–1) or an equal volume of placebo during hours 0–12 and 24–36 postexercise in a double-blind, crossover protocol. Muscle soreness; midbrachial arm circumference; blood glucose, IL-6, CRP, cortisol, and creatine-kinase (CK) activity; and maximal force production were measured preexercise and 4, 8, 12, 24, 48, and 120 h postexercise. Plasma IL-6 increased, F(5) = 5.27, P < 0.05, 8 h postexercise, with no difference between carbohydrate and placebo conditions. Changes in muscle soreness, arm circumference, strength, and serum CK activity were consistent with small amounts of muscle damage and did not differ between conditions. The authors conclude that carbohydrate supplementation during recovery from soreness-inducing exercise does not influence the delayed IL-6 response temporally linked to inflammation or indications of muscle damage. Thus, increased carbohydrate consumption at levels consistent with recommendations for replenishing glycogen stores does not impair or promote the immune and muscle responses.