Browsing by Author "Depner, Chris M."

Now showing 1 - 4 of 4

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.
Do carbohydrates increase the magnitude of the inflammatory response
(Montana State University - Bozeman, College of Education, Health & Human Development, 2008) Depner, Chris M.; Chairperson, Graduate Committee: Mary P. Miles.
Inflammation is the body's response to tissue damage and infection and is correlated with several chronic diseases like type II diabetes. Cytokines are cell signaling proteins with multiple functions including control of inflammation. Cytokines are influenced by several factors such as carbohydrate intake and exercise. Thus, carbohydrate intake and exercise can influence inflammation. Purpose: To determine the influence of high carbohydrate intake on the inflammatory response to exercise that induces muscle damage and inflammation. Methods: The study was a cross-over design. Each subject completed a high carbohydrate condition and a high fat and protein condition. Each condition consisted of 6 sets of 10 maximal high-force eccentric contractions of the elbow flexors and extensors. The exercise was followed by a controlled diet for the first 8 hours post-exercise based on the condition. The cytokines interleukin-6 (IL-6) and interleukin-1B (IL-B) were measured as indicators of local inflammation. C-reactive protein (CRP) was measured as an indicator of systemic inflammation. Creatine-kinase (CK), muscle soreness, upper arm circumference, and strength loss were measured as indicators of muscle damage. Blood glucose and insulin were measured to identify differences between diets in the conditions. Results: Insulin was significantly increased in the high carbohydrate condition compared to the high fat and protein condition at 1.5, 4, and 8 hours post-exercise. Perceived soreness was elevated at all time points post-exercise in both conditions and was significantly elevated in the high carbohydrate condition compared to the high fat and protein condition. There was a main effect trend for IL-6 to be greater in the high carbohydrate condition compared to the high fat and protein condition. Il-1B was significantly increased 24 hours post-exercise in the high carbohydrate condition compared to the high fat and protein condition. Conclusion: Elevated carbohydrate intake post-exercise augmented the local inflammatory response to the exercise observed by elevated IL-1B and IL-6. The augmented inflammatory response contributed to greater perceived muscle soreness post-exercise. Further research is required to investigate this mechanism further to provide better prevention and treatment methods for chronic diseases related to inflammation.
Enhanced inflammation with high carbohydrate intake during recovery from eccentric exercise
(Springer, 2010-08) Miles, Mary; Depner, Chris M.; Kirwan, Rochelle D.; Frederickson, Sara J.
Inflammation associated with adipose tissue is modulated by macronutrient availability. For example, glucose increases inflammation in obese but not lean individuals. Little is known about how macronutrient intake influences inflammation associated with muscle. The aim of this study was to determine the impact of macronutrient intake differences during recovery from eccentric exercise on the inflammatory response. The study was a cross-over design in which young men and women (n = 12) completed high and low carbohydrate (CHO) conditions. Both conditions consisted of six sets of ten maximal high-force eccentric contractions of the elbow flexors and extensors followed by a controlled diet for the first 8 h post-exercise. Glucose, insulin, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and C-reactive protein were measured from blood samples pre-exercise, 1.5, 4, 8, and 24 h post-exercise. Perceived muscle soreness, strength loss, and serum CK activity were measured through 120 h post-exercise. Perceived soreness was elevated (P < 0.001) at all time points post-exercise in both conditions and was higher (P < 0.05) in the high compared to the low CHO condition. IL-1β increased (P = 0.05) 24 h post-exercise in the high compared to the low CHO condition. There was a trend (P = 0.06) for IL-6 to be elevated in the high compared to the low CHO condition. We conclude that inflammation induced by high-force eccentric exercise in skeletal muscle is greater when a high CHO compared to a low CHO diet is consumed during recovery.
Influence of macronutrient intake and anthropometric characteristics on plasma insulin after eccentric exercise
(W.B. Saunders Co, 2010-10) Miles, Mary; Frederickson, Sara J.; Depner, Chris M.; Kirwan, Rochelle D.
To increase understanding of the interaction between macronutrients and insulin resistance (IR), this study sought to determine the influence of macronutrient intake and anthropometric differences on IR and inflammation responses to eccentric resistance exercise. Men and women (n = 12, 19-36 years old) participated in a crossover study and completed 6 sets of 10 unilateral maximal eccentric contractions of the elbow flexors and extensors followed by controlled diet conditions for the first 8 hours postexercise of carbohydrate/fat/protein proportions of either 75%/15%/10% (CHO) or 6%/70%/24% (FAT/PRO). Fasting glucose, insulin, homeostatic model assessment (HOMA) variables, and interleukin (IL)-1β were measured preexercise and 23 hours postexercise (additional measures of glucose and insulin 1 hour after meals consumed 0.5, 3, and 7 hours postexercise). Insulin increased more (P < .01) in the CHO compared with the FAT/PRO condition at 1.5, 4, and 8 hours postexercise. Insulin, HOMA-IR, and HOMA-β-cell function increased 23 hours postexercise in both conditions, whereas IL-1β increased 23 hours postexercise only in the CHO condition. Magnitude of change (Δ) for these variables associated positively with body mass index (BMI) and waist to hip ratio (WHR) in the CHO and inversely in the FAT/PRO condition; that is, r = 0.53 (P = .10) and r = −0.82 (P < .01) for BMI vs Δ insulin in CHO and FAT/PRO conditions, respectively. The Δ IL-1β associated with BMI (r = 0.62, P < .05) and WHR (r = 0.84, P < .01) in the CHO condition. The CHO enhanced IR and inflammation as BMI and WHR increased, whereas fat and protein enhanced IR as BMI and WHR decreased. Thus, BMI and WHR may need to be taken into account in the development of nutritional strategies to prevent IR.