Browsing by Author "Miles, Mary"

Now showing 1 - 18 of 18

Apolipoprotein A1 genotype affects the change in high density lipoprotein cholesterol subfractions with exercise training.
(2006-03) Ruaño, G.; Seip, R.L.; Windemuth, Andreas; Zöllner, S.; Tsongalis, Gregory J.; Otvos, J.; Ordovas, J.M.; Bilbie, C.; Miles, Mary; Zoeller, Robert F.; Visich, Paul S.; Gordon, P.M.; Angelopoulos, T.J.; Pescatello, Linda S.; Moyna, Niall M.; Thompson, P.D.
High density lipoprotein cholesterol (HDL-C) is a primary risk factor for cardiovascular disease. Apolipoprotein A-1 (apoA1) is the major HDL-associated apolipoprotein. The −75 G/A single nucleotide polymorphism (SNP) in the apolipoprotein A1 gene (APOA1) promoter has been reported to be associated with HDL-C concentrations as well as HDL-C response to dietary changes in polyunsaturated fat intake. We examined the effect of this APOA1 SNP on exercise-induced changes in HDL subfraction distribution. From a cohort of healthy normolipidemic adults who volunteered for 6 months of supervised aerobic exercise, 75 subjects were genotyped for the −75 G/A SNP. Of these, 53 subjects were G homozygotes (G/G) and 22 were A carriers (A/G and A/A). HDL subfractions were measured by nuclear magnetic resonance (NMR) spectroscopy by adding categories HDL-C 1 + 2 for the small subfraction, and HDL-C 3 + 4 + 5 for the large. The change in total HDL-C after exercise was 0.8 ± 7.2 mg/dL (+1.7%), and was not statistically significant. HDL subfraction amounts also did not significantly change with exercise training in the total cohort or in G homozygotes or A carriers. The amount of the large HDL subfraction increased in the G homozygotes and decreased in the A carriers (mean ± S.E.M., 1.8 ± 6.6 mg/dL versus −6.1 ± 2.3 mg/dL, p < 0.0005). In contrast, the amount of the small HDL subfraction decreased in G homozygotes and increased in A carriers (−1.3 ± 6.6 mg/dL versus 4.7 ± 1.2 mg/dL, p < 0.005). These results show that genetic variation at the APOA1 gene promoter is associated with HDL subfraction redistribution resulting from exercise training.
Apolipoprotein E genotype and changes in serum lipids and maximal oxygen uptake with exercise training
(W.B. Saunders Co, 2004) Thompson, P.D.; Tsongalis, Gregory J.; Seip, R.L.; Bilbie, C.; Miles, Mary; Zoeller, Robert F.; Visich, Paul S.; Gordon, P.M.; Angelopoulos, T.J.; Pescatello, Linda S.; Bausserman, L.; Moyna, Niall M.
Physical activity improves lipid levels by altering triglyceride (TG) metabolism. Apolipoprotein E (Apo E) facilitates TG clearance by mediating lipoprotein binding to hepatic receptors, but Apo E also has less defined roles in skeletal muscle and nervous tissue. This study examined if variants in Apo E genotype affect the lipid and physiologic response to exercise training. Seven centers genetically screened 566 individuals to recruit 120 subjects into 6 gender-specific cohorts equal for the most common Apo E genotypes: E2/3, E3/3, and E3/4. Anthropometics, exercise capacity (Vo2max), serum lipids, and post heparin (PH) plasma lipase activities were measured before and after 6 months of supervised exercise training. Difference in the response (Δ) to training among the Apo E genotypes was the primary outcome variable. Differences in pretraining serum lipids among the Apo E genotypes mimicked those observed in population studies: TGs were slightly higher in E2/3 subjects, whereas low-density lipoprotein (LDL)-cholesterol (C) was lower (P = not significant [NS] ). TGs decreased 11% with training for the entire cohort (P < .0001) and 7%, 12%, and 14% for the Apo E 2/3, 3/3 and 3/4 groups, respectively (P = NS for Δ). LDL-C did not change in the entire cohort, but decreased slightly in the 2/3 and 3/3 subjects and increased 4% in the 3/4 group (P = NS for Δ). High-density lipoprotein (HDL)-C increased 2% for the entire cohort (P = .06) due to a 6% increase in the 3/3 group (P = .07 for Δ). Total cholesterol (TC)/HDL and LDL/HDL decreased with training in the 2/3 and 3/3 groups, but increased in the 3/4 subjects and these responses differed among the genotypes (P < .05 for Δ). Vo2max increased 9% to 10% for the entire cohort, but only 5% in the 3/3 subjects versus 13% in the 2/3 and 3/4 groups and these differences were significantly different among the genotypes (P < .01 for Δ). This is the first prospective study to demonstrate that the serum lipid response to exercise training differs by Apo E genotype in a pattern consistent with known metabolic differences among the variants. Surprisingly, Apo E genotype also affected the increase in aerobic capacity produced by exercise training possibly via undefined effects on nerve and skeletal muscle function.
Apolipoprotein E genotype and sex influence C-reactive protein levels regardless of exercise training status
(W.B. Saunders Co, 2008) Miles, Mary; Lowndes, J.; Sivo, S.; Seip, R.L.; Angelopoulos, T.J.
C-reactive protein (CRP) is a marker for systemic inflammation and increased cardiovascular disease risk. Regular exercise may decrease CRP. Apolipoprotein E (apo E) has 3 common genotype variants—E2/3, 3/3, and 3/4—that modulate lipid metabolism and may have other metabolic physiologic roles, including some evidence that the genotype affects CRP levels. We assessed fasting serum CRP in 117 (male = 51, female = 66) healthy adults who volunteered for a 6-month aerobic exercise program. Both pre- and posttraining measurements were available in 71 (male = 31, female = 40) subjects. At baseline and follow-up, the numbers of subjects in the 3 groups were approximately equal: 2/3, n = 33 and 20; 3/3, n = 41 and 26; and 3/4, n = 43 and 25. At baseline, CRP levels differed by apo E genotype: means ± SD were 2.84 ± 2.18, 2.59 ± 2.34, and 1.90 ± 2.13 mg/L for E2/3, 3/3, and 3/4 subjects, respectively (3/4 vs 2/3, P b .05). In women, CRP was higher than that in men (3.14 ± 2.49 vs 2.12 ± 2.13 mg/L, P b .006). Exercise failed to affect CRP in the entire cohort (2.68 ± 2.38 vs 2.52 ± 2.48 mg/L) or in any apo E genotype group, and the apo E genotype effect observed at baseline persisted after training. In a largely white study cohort, CRP is higher in apo E3/3 than in 3/4 subjects and in women compared with men, but remains unchanged by 6 months of standard aerobic exercise training of the volume and higher intensity promoted by national organizations to reduce cardiovascular disease risk. How apo E genotype affects CRP is not known.
Basal, diurnal, and acute inflammation in normal versus overweight men.
(Lippincott Williams & Wilkins, 2012-12) Miles, Mary; Keller, J.M.; Kordick, L.K.; Kidd, J.R.
Increased inflammation is present in obese compared with normal weight individuals, but inflammation characteristics of nonobese, overweight individuals are less clear. Purpose: The objective of this study was to determine whether basal, circadian, and posteccentric exercise inflammation levels differ between normal and overweight men. Methods: Men (18–35 yr old) classified as normal weight (body mass index ≤2 5 kg·m-2, n = 20) and overweight (body mass index = 25–30 kg·m-2 conditions in random order. Maximal voluntary effort and eccentric actions (3 X 15) using the elbow flexor muscles of one arm were performed, and blood was collected preexercise and 4, 8, 12, and 24 h postexercise at 7:00 a.m., 12:00 p.m., 4:00 p.m., 8:00 p.m., and 7:00 a.m. Blood was collected on a time-matched schedule without exercise for CON. Soluble tumor necrosis factor receptor-1, interleukin-6, C-reactive protein (CRP), and cortisol responses (EX value j time-matched CON value) were measured. Results: Basal CRP was higher in the overweight compared with normal weight group (mean ± SD, 0.542 ± 0.578 vs 1.395 ± 1.041 mg·L-1). Soluble tumor necrosis factor receptor-1 increased (P < 0.05) 8 h postexercise in both groups, and the response was greater 12 and 24 h postexercise in the overweight compared with normal weight groups. Interleukin-6 increased (P < 0.05) 8 h postexercise, with a trend (P = 0.09) to be greater in the overweight group. CRP and cortisol responses were not detected. Conclusions: The low-grade inflammation state in overweight compared with normal weight men includes both higher basal CRP concentrations and enhanced acute inflammation, but not in changes to the circadian patterns of cortisol and inflammation variables.
Carbohydrate Influences Interleukin-6 but not C-reactive Protein or Creatine Kinase Following a 32-km Mountain Trail Race
(Human Kinetics, 2005) Miles, Mary; Walker, E.E.; Conant, S.B.; Hogan, S.P.; Kidd, J.R.
Attenuation of exercise-induced interleukin-6 (IL-6) responses by carbohydrate (CHO) has been demonstrated in studies comparing controlled doses (≥ 0.9 g · kg–1 · h–1) to placebo, but not in studies of voluntary intake. This study sought to determine if attenuation of the IL-6 response during a 32.2-km mountain trail race occurs for high compared to low ad libitum CHO intakes. IL-6, C-reactive protein (CRP), and creatine kinase activity (CK) were analyzed from blood samples collected 12 h pre-, 0, 4, and 24 h post-race. Subjects were grouped into low (n =14, 0.4 ± 0.1 g · kg–1· h–1) and high (n =18, 0.8 ± 0.2 g · kg–1 · h–1) CHO intake groups. IL-6 0 h post-race (P < 0.05) was higher in the low (40.2 ± 22.7 pg · mL–1) compared to the high CHO group (32.7 ± 22.1 pg · mL–1). CRP and CK both increased post-race, but no differences were observed between groups. Attenuation of exercise-induced IL-6 is apparent across a range of CHO intakes.
Carbohydrates for physical activity: A strategy to avoid undesirable health consequences
(2012-03) Miles, Mary
Intake of carbohydrates above the dietary guidelines to support performance of physical activity is common but may be unnecessary and counterproductive. Sports nutrition guidelines have not been designed to incorporate characteristics that may make high carbohydrate consumption a source of metabolic stress that may increase oxidative stress, inflammation, and lipogenesis. This metabolic stress is linked to the physiology underlying the development of insulin resistance, type 2 diabetes mellitus, and cardiovascular diseases. This review describes research-based evidence to aid in bridging the gap between dietary guidelines for overall health and those to support physical activity. Characteristics that increase the likelihood of metabolic stress resulting from carbohydrate intake include overweight and obesity, central/visceral adiposity, older age, sedentary lifestyle, and caloric state. Carbohydrate-based foods that provide the most health benefits are whole grains, beans and legumes, fruits, and vegetables. Carbohydrate-based foods that most readily elicit metabolic stress are those with added sugars and refined grains or that have a high glycemic index. A checklist that incorporates both the number of these characteristics and prevailing guidelines for nutrition and physical activity is presented. This may be useful in determining whether additional carbohydrates are needed to support the physical activity level of the individual.
Creatine supplementation does not reduce muscle damage or enhance recovery from resistance exercise
(2007-11) Rawson, E.S.; Conti, M.P.; Miles, Mary
Previous studies have shown that creatine supplementation reduces muscle damage and inﬂammation following running but not following high-force, eccentric exercise. Although the mechanical strain placed on muscle ﬁbers during high-force, eccentric exercise may be too overwhelming for creatine to exert any protective effect, creatine supplementation may protect skeletal muscle stressed by a resistance training challenge that is more hypoxic in nature. The purpose of this study was to examine the effects of short-term creatine supplementation on markers of muscle damage (i.e., strength, range of motion, muscle soreness, muscle serum protein activity, C-reactive protein) to determine whether creatine supplementation offers protective effects on skeletal muscle following a hypoxic resistance exercise test. Twenty-two healthy, weight-trained men (19–27 years) ingested either creatine or a placebo for 10 days. Following 5 days of supplementation, subjects performed a squat exercise protocol (5 sets of 15–20 repetitions at 50% of 1 repetition maximum [1RM]). Assessments of creatine kinase (CK) and lactate dehydrogenase activity, high-sensitivity C-reactive protein, maximal strength, range of motion (ROM), and muscle soreness (SOR) with movement and palpation were conducted pre-exercise and during a 5-day follow up. Following the exercise test, maximal strength and ROM decreased, whereas SOR and CK increased. Creatine and placebo-supplemented subjects experienced signiﬁcant decreases in maximal strength (creatine: 13.4 kg, placebo: 17.5 kg) and ROM (creatine: 2.4°, placebo: 3.0°) immediately postexercise, with no difference be-tween groups. Following the exercise test, there were signiﬁcant increases in SOR with movement and palpation (p < 0.05 at 24, 48, and 72 hours postexercise), and CK activity (p < 0.05 at 24 and 48 hours postexercise), with no differences between groups at any time. These data suggest that oral creatine supplementation does not reduce skeletal muscle damage or enhance recovery following a hypoxic resistance exercise challenge.
Cultural and Economic Factors Affecting Diet and Nutrition in Children in Khwisero, Kenya
(2013-03) Jauquet, Kala; Miles, Mary
The purpose of this research project is to identify economic and cultural factors influencing food availability and diet in Khwisero, Kenya. Information gained in the study was used to explain malnutrition rates of children including stunting, wasting, and Kwashiorkor. Research was performed in Khwisero, Kenya for one month while working with Engineers Without Borders. A three-day dietary analysis was obtained by recording all food and drink consumed by the researcher. Information on economic and cultural factors influencing diet and nutrition were obtained through nine household interviews and extensive informal conversation with community members. The dietary analysis showed deficiencies of vitamins A, E, C, B12, potassium, zinc, iron, calcium, niacin, and magnesium. Foods rich in these nutrients are not widely available to Khwisero residents due to poor farming practices and high poverty rates. Cultural beliefs and traditions about diet and nutrition have impacted types of foods grown and consumed, as some foods are valued higher than others. Kwashiorkor was established as the most commonly found symptom of malnutrition among primary school children caused by a protein deficiency. Population and food availability was found to be the cause of the disease, as protein content in the diet was sufficient given proper caloric intake. Education of women, better farming practices, and culturally shifting cooking and eating habits may be beneficial in improving diet and malnutrition rates in Khwisero.
Cytokine production by stimulated mononuclear cells did not change with aging in apparently healthy, well-nourished women
(Elsevier, 2001) Ahluwalia, N.; Mastro, A.M.; Ball, R.; Miles, Mary; Rajendra, R.; Handte, G.
Aging is often associated with a dysregulation of the immune system. We examined mitogen-stimulated production of interleukin (IL)-2 and proinflammatory cytokines, IL-1β and IL-6, in apparently healthy and generally well-nourished old versus young women. Subjects were screened for health using the SENIEUR protocol and a panel of laboratory tests for inflammation, as well as for the adequacy of nutritional status using criteria related to undernutrition, and protein, iron, vitamin B12, and folate status. Young (n=26, age: 20–40 years) and old (n=44, age: 62–88 years) cohorts did not differ on the number of circulating monocytes, granulocytes, B (CD19+) cells, and T (CD3+, CD4+, and CD8+) cells. No differences (P>0.10) were seen between the two age groups in IL-2, IL-1β and IL-6 levels in whole blood cultures at 48 h after stimulation with PHA (5 mg/l). Furthermore, no age-related differences were noted in the absolute amounts (pg) of IL-1β and IL-6 after normalizing for circulating monocytes, B cells, or T cells (P>0.10). Similarly, no age-related decline in absolute amount of IL-2 (pg) after normalizing for circulating T cells was noted (P>0.10). Thus, contrary to most previous reports, our results do not support an increase in the production of proinflammatory cytokines IL-1β and IL-6, and a reduced production of IL-2 with aging when health and nutritional status are maintained. These findings support our previous results of no change in monocyte function and few alterations in acquired immune response in a carefully selected group of healthy and well-nourished elderly women.
Dietary, Anthropometric, Blood Lipid, and Performance Patterns of College Football Players During 8 Weeks of Training
(Human Kinetics, 2012) Miles, Mary; Kirwan, Rochelle D.; Kordick, L.K.; McFarland, S.; Lancaster, D.; Clark, K.
The purpose of this study was to determine the dietary, anthropometric, blood-lipid, and performance patterns of university-level American football players attempting to increase body mass during 8 wk of training. Methods: Three-day diet records, body composition (DEXA scan), blood lipids, and performance measures were collected in redshirt football players (N = 15, age 18.5 ± 0.6 yr) early season and after 8 wk of in-season training. Results: There was an increase (p < .05) from early-season to postseason testing for reported energy (+45%), carbohydrate (+82%), and protein (+29%) intakes and no change in the intake of fat. Fat intake was 41% of energy at the early-season test and 32% of energy at the postseason test. Increases (p < .05 for all) in performance measures, lean mass (70.5 ± 7.7–71.8 ± 7.7 kg), fat mass (15.9 ± 6.2–17.3 ± 6.8 kg), plasma total cholesterol (193.5 ± 32.4–222.6 ± 40.0 mg/dl), and low-density lipoproteins (LDL; 92.7 ± 32.7–124.5 ± 34.7 mg/dl) were measured. No changes were measured in triglycerides, very-low-density lipoproteins, or high-density lipoproteins. Conclusion: Increases in strength, power, speed, total body mass, muscle mass, and fat mass were measured. Cholesterol and LDL levels increased during the study to levels associated with higher risk for cardiovascular disease. It is possible that this is a temporary phenomenon, but it is cause for concern and an indication that dietary education to promote weight gain in a manner less likely to adversely affect the lipid profile is warranted.
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.
Effects of eccentric muscle contraction and a high- or low-glycemic diet on inflammation
(2013-03) Ruegsegger, Gregory; Miles, Mary
Downhill running promotes eccentric muscular contractions and is a common cause of muscle damage. After muscle-damaging exercises, such as exercise that promotes high-force eccentric muscular contraction, inflammatory cells produce an array of cytokines to produce, and mediate, an acute inflammatory response. One cytokine associated with the inflammatory response after exercise is interleukin-6 (IL-6). During the inflammatory response IL-6 provides feedback inhibition to prohibit the synthesis of pro-inflammatory cytokines that stimulate a further inflammatory response and induces synthesis of anti-inflammatory mediators. It has been shown that differences in glycemic index enhance the synthesis of several inflammatory cytokines, and possibly IL-6. The aim of this research was to compare the effects of downhill running coupled with either a high (HGI) or low-glycemic index (LGI) diet on serum IL-6 levels in overweight women. Participants (n=20) completed a standardized downhill running protocol and were randomly provided with a HGI or LGI diet for a 24 hour period post-exercise. IL-6 was measured using standard approaches at times pre-, 0, 24, and 48 h post-exercise. For the subjects analyzed (n=10, 5 LGI, 5 HGI) there were significant differences in IL-6 and ΔIL-6 levels between pre and 0 h post-exercise (p=0.02 and 0.04 respectively) but no significant differences between interventions (p=0.16 and 0.32 respectively). Because of the small sample size, these results are inconclusive and analysis of the remaining subjects is needed to determine the influence of glycemic index alteration on IL-6 levels and the magnitude of 24 and 48 h post-exercise 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.
Interactive Effects of APOE Haplotype, Sex, and Exercise on Postheparin Plasma Lipase Activities
(American Physiological Society, 2011) Miles, Mary; Seip, R.L.; Zoeller, Robert F.; Angelopoulos, T.J.; Salonia, J.; Bilbie, C.; Moyna, Niall M.; Visich, Paul S.; Pescatello, Linda S.; Gordon, P.M.; Tsongalis, Gregory J.; Bausserman, L.; Thompson, P.D.
Hepatic lipase (HL) and lipoprotein lipase (LPL) activities (HLA, LPLA) modify lipoproteins and facilitate their binding to hepatic receptors. Apolipoprotein E (APOE) physically interacts with the lipases, and the three common haplotypes of the APOE gene (ε2, ε3, and ε4) yield protein isoforms (E2, E3, and E4, respectively) that are functionally different. Lipase activities themselves differ by sex and exercise training status. The interaction of APOE genotype, exercise training, and sex effects on lipase activities has not been studied. We measured postheparin plasma lipase activities in normolipidemic men and women with the three most common APOE genotypes, which are the haplotype combinations ε2/ε3 (n 53 ), ε3/ε3 (n 62), and ε4/ε3 (n 52), enrolled in 6 mo of aerobic exercise training. These haplotype combinations comprise an estimated 11.6, 62.3, and 21.3% of the population, respectively. Baseline HLA was 35% lower in women than in men (P 0.0001). In men but not women, HLA was higher in ε2/ε3 group compared with ε4/ε3 (P 0.01) and ε3/ε3 (P 0.05). Neither sex nor APOE genotype affected baseline LPLA. Training decreased HLA by 5.2% (P 0.018) with no APOE effect. The apparent increase in LPLA following exercise was significant and APOE dependent only when corrected for baseline insulin (P 0.05). Exercise decreased LPLA by 0.8 mol free fatty acid (FFA)·ml 1·h 1 ( 6%) in ε3/ε3 compared with the combined increases of 6.6% in ε2/ε3 and 12% in ε4/ε3 (P 0.018 vs. ε3/ε3). However, these differences were statistically significant only after correcting for baseline insulin. We conclude that common APOE genotypes interact with 1) sex to modulate HLA regardless of training status, with ε2/ε3 men demonstrating higher HLA than ε3/ε3 or ε4/ε3 men, and 2) aerobic training to modulate LPLA, regardless of sex, with ε3/ε3 subjects showing a significant decrease compared with an increase in ε2/ε3 and ε3/ε4 after controlling for baseline insulin.
Leukocyte Adhesion Molecule Expression During Intense Resistance Exercise
(American Physiological Society, 1998) Miles, Mary; Leach, S.K.; Kraemer, W.J.; Dohi, K.; Bush, J.A.; Mastro, A.M.
We hypothesized that expression of L-selectin and very late antigen-4 (VLA-4) integrin adhesion molecules would influence cell type-specific redistribution during exercise. Women subjects performed six sets of 10-repetition maximum squats. L-selectin and VLA-4 integrin were measured by using flow cytometry pre- and postexercise on peripheral blood neutrophils and lymphocytes (n 5 29 subjects) and lymphocyte subsets (n 5 70 subjects), respectively. Neutrophil concentration increased 41.8% (P , 0.001), whereas the percent expressing L-selectin was unchanged (79%). Lymphocyte concentration increased 61.8% (P , 0.001). The percent of T cells expressing L-selectin decreased from 73.5 6 8.9 to 68.2 6 11.4% (P , 0.001); the combined population of natural killer and B cells expressing L-selectin decreased from 80.4 6 22.5 to 62.7 6 25.8% (P , 0.001). VLA-4 integrin was expressed by nearly all lymphocytes both pre- and postexercise. The proportional decrease in L-selectin positive cells could have resulted from 1) shedding of L-selectin, 2) selective entry of L-selectin-negative subsets, or 3) selective removal of L-selectin-positive subsets.
Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain
(Elsevier, 2011-04) Miles, Mary; Rawson, E.S.; Stech, M.J.; Frederickson, Sara J.
Objective: We examined the effects of 6 wk of low-dose creatine supplementation on body composition, muscle function, and body creatine retention. Methods: Twenty healthy men and women (21 ± 2 y old) were randomized to receive creatine (0.03 g • kg ^-1 • d-1; n=10, 4 women) for 6 wk in a double-blind placebo-controlled fashion. Participants were tested on two occasions before supplementation to establish a reliable baseline, and then were retested after supplementation. Testing included body composition, maximal strength (three-repetition maximal concentric knee extension at 180 degrees/s), muscle fatigue (five sets of 30 concentric knee extensions at 180 degrees/s), and plasma creatine concentration. Results: There were no significant differences in body mass, fat-free mass, fat mass, body fat percentage, total body water, or maximal strength in either group from before to after supple-mentation (all P > 0.05). After supplementation, plasma creatine increased significantly in the creatine group (+182%, P = 0.03), with no difference in the placebo group. Compared with baseline values, creatine-supplemented volunteers were more resistant to fatigue during sets 2 (7%), 3 (9%), 4 (9%), and 5 (11%) (all P < 0.05). In placebo-supplemented participants, there was no improvement in fatigue resistance during sets 2 (0%), 3 (1%), 4 (0%), and 5 (1%) (all P > 0.05). Conclusion: Ingesting a low dose (2.3 g/d) of creatine for 6 wk significantly increased plasma creatine concentration and enhanced resistance to fatigue during repeated bouts of high-intensity contractions.