Twelve Weeks of Daily Lentil Consumption Improves Fasting Cholesterol and Postprandial Glucose and Inflammatory Responses-A Randomized Clinical Trial.

Lentils have potential to improve metabolic health but there are limited randomized clinical trials evaluating their comprehensive impact on metabolism. The aim of this study was to assess the impact of lentil-based vs. meat-based meals on fasting and postprandial measures of glucose and lipid metabolism and inflammation. Thirty-eight adults with an increased waist circumference (male ≥ 40 inches and female ≥ 35 inches) participated in a 12-week dietary intervention that included seven prepared midday meals totaling either 980 g (LEN) or 0 g (CON) of cooked green lentils per week. Linear models were used to assess changes in fasting and postprandial markers from pre- to post-intervention by meal group. Gastrointestinal (GI) symptoms were assessed through a survey randomly delivered once per week during the intervention. We found that regular consumption of lentils lowered fasting LDL (F = 5.53, p = 0.02) and total cholesterol levels (F = 8.64, p < 0.01) as well as postprandial glucose (ß = -0.99, p = 0.01), IL-17 (ß = -0.68, p = 0.04), and IL-1ß (ß = -0.70, p = 0.03) responses. GI symptoms were not different by meal group and all symptoms were reported as "none" or "mild" for the duration of the intervention. Our results suggest that daily lentil consumption may be helpful in lowering cholesterol and postprandial glycemic and inflammatory responses without causing GI stress. This information further informs the development of pulse-based dietary strategies to lower disease risk and to slow or reverse metabolic disease progression in at-risk populations.

Metabolic impact of polyphenol-rich aronia fruit juice mediated by inflammation status of gut microbiome donors in humanized mouse model.

Background: The Aronia melanocarpa fruit is emerging as a health food owing to its high polyphenolic content and associated antioxidant activity. Antioxidant-rich foods, such as Aronia fruit, may counter inflammatory stimuli and positively modulate the gut microbiome. However, a comprehensive study characterizing the impact of Aronia fruit supplementation has not been completed. Therefore, we completed analyses measuring the metabolic, microbial, and inflammatory effects of a diet supplemented with Aronia fruit juice. Method: Humanized mice were generated by colonizing gnotobiotic mice with microbiomes from human donors presenting disparate inflammation levels. Blood and fecal samples were collected throughout the course of an 8-week dietary intervention with either Aronia juice or a carbohydrate-matched beverage alone (2 weeks) or in combination with a high-fat diet to induce inflammation (6 weeks). Samples were analyzed using 16S rRNA gene sequencing (stool) and liquid chromatography-mass spectrometry (serum). Results: We demonstrated transfer of microbiome composition and diversity and metabolic characteristics from humans with low and high inflammation levels to second-generation humanized mice. Aronia supplementation provided robust protection against high-fat diet induced metabolic and microbiome changes that were dependent in part on microbiome donor. Aronia induced increases in bacteria of the Eggerthellaceae genus (7-fold) which aligns with its known ability to metabolize (poly)phenols and in phosphatidylcholine metabolites which are consistent with improved gut barrier function. The gut microbiome from a low inflammation phenotype donor provided protection against high-fat diet induced loss of microbiome ß-diversity and global metabolomic shifts compared to that from the high inflammation donor. Conclusion: These metabolic changes elucidate pathway-specific drivers of reduced inflammation stemming from both Aronia and the gut microbiota.

Eight weeks of lentil consumption attenuates insulin resistance progression without increased gastrointestinal symptom severity: A randomized clinical trial.

Lentils lower acute glycemic responses and promote satiety, benefits that may aid in chronic disease prevention. However, perceived gastrointestinal (GI) effects may deter inclusion of dietary pulses in the diet. We hypothesized that 8 weeks of lentil-based vs meat-based meals would improve glycemic control and improve satiety in metabolically at-risk, nondiabetic adults. Because GI symptoms are rarely reported, we also explored the temporal effects of symptom severity. Adults with an increased waist circumference (male > 40 inches, female > 35 inches) participated in an 8-week dietary intervention that included 5 prepared midday meals each week that were isocaloric but varied in cooked green lentil dosage: 0 g (CON), 300 g (MOD), or 600 g (HI). Assessments included glucose and insulin integrated area under the curve measured during a 75-g carbohydrate tolerance test, hepatic Homeostatic Model of Insulin Resistance (HOMA-IR), and peripheral insulin resistance. On 1 randomized day each week, satiety was assessed at 4:00 pm and GI symptoms at 8:00 pm. A linear model assessed changes in glycemic and GI measures by meal group. Thirty adults (mean ± SD; age, 41.6 ± 11.7 years, body mass index, 35.1 ± 6.3) completed the intervention. HOMA-IR increased in CON (+1.2 units) and decreased in a dose-dependent manner in MOD (-0.9 units, P = .03) and HI (-1.5 units, P < .01) relative to CON. Most participants (87.4%) reported no to mild GI symptoms. Of these, flatulence was mild on average with bloating, abdominal discomfort, and cramping severity 0.3, 0.5, and 0.5 units lower (P < .001). We observed a dose-dependent reduction on rising hepatic insulin resistance and low GI symptom severity with long-term lentil consumption in metabolically at-risk adults.

Determinants of the postprandial triglyceride response to a high-fat meal in healthy overweight and obese adults.

BACKGROUND: Dyslipidemia is a feature of impaired metabolic health in conjunction with impaired glucose metabolism and central obesity. However, the contribution of factors to postprandial lipemia in healthy but metabolically at-risk adults is not well understood. We investigated the collective contribution of several physiologic and lifestyle factors to postprandial triglyceride (TG) response to a high-fat meal in healthy, overweight and obese adults. METHODS: Overweight and obese adults (n = 35) underwent a high-fat meal challenge with blood sampled at fasting and hourly in the 4-hour postprandial period after a breakfast containing 50 g fat. Incremental area under the curve (iAUC) and postprandial magnitude for TG were calculated and data analyzed using a linear model with physiologic and lifestyle characteristics as explanatory variables. Model reduction was used to assess which explanatory variables contributed most to the postprandial TG response. RESULTS: TG responses to a high-fat meal were variable between individuals, with approximately 57 % of participants exceeded the nonfasting threshold for hypertriglyceridemia. Visceral adiposity was the strongest predictor of TG iAUC (ß = 0.53, p = 0.01), followed by aerobic exercise frequency (ß = 0.31, p = 0.05), insulin resistance based on HOMA-IR (ß = 0.30, p = 0.04), and relative exercise intensity at which substrate utilization crossover occurred (ß = 0.05, p = 0.04). For postprandial TG magnitude, visceral adiposity was a strong predictor (ß = 0.43, p < 0.001) followed by aerobic exercise frequency (ß = 0.23, p = 0.01), and exercise intensity for substrate utilization crossover (ß = 0.53, p = 0.01). CONCLUSIONS: Postprandial TG responses to a high-fat meal was partially explained by several physiologic and lifestyle characteristics, including visceral adiposity, insulin resistance, aerobic exercise frequency, and relative substrate utilization crossover during exercise. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04128839 , Registered 16 October 2019 - Retrospectively registered.

Temporal metabolic response yields a dynamic biosignature of inflammation.

Chronic low-grade inflammation is a subclinical condition directly and indirectly linked to the development of a wide range of diseases responsible for the vast majority of morbidity. To examine mechanisms coupled to chronic disease, a group of overweight and obese human subjects without known inflammatory diseases participated in a high-fat meal challenge as an acute inflammation stimulus. Analysis of serum metabolites grouped by baseline cytokine levels revealed that single samples had little power in differentiating groups. However, an analysis that incorporated temporal response separated inflammatory response phenotypes and allowed us to create a metabolic signature of inflammation which revealed metabolic components that are crucial to a cytokine-mediated inflammation response. The use of temporal response, rather than a single time point, improved metabolomic prediction of high postprandial inflammation responses and led to the development of a dynamic biosignature as a potential tool for stratifying risk to a wide range of diseases.

The effects of foods available through the Food Distribution Program on Indian Reservations (FDPIR) on inflammation response, appetite and energy intake.

OBJECTIVE: To compare the effects of a typical Food Distribution Program on Indian Reservations (FDPIR) diet with an FDPIR diet that meets Dietary Guidelines for Americans (DGA) on inflammation response, appetite and energy intake on a combination of American Indian (AI) and non-AI individuals. DESIGN: A within-subjects, randomised, crossover design was used to compare two dietary conditions: (1) a FDPIR diet that met DGA and (2) a FDPIR diet that did not meet DGA. Each participant served as their own control and was exposed to both dietary conditions. Repeated-measures ANOVA and t tests assessed significance between the two dietary conditions. SETTING: This took place in the Montana State University Nutrition Research Laboratory in the USA. PARTICIPANTS: Female and male participants (n 13) aged 18-55 years from the university and local community. RESULTS: There were no significant differences in inflammatory response and appetite sensations between the two dietary conditions. Findings indicated that participants ate 14 % more (P < 0·01) kcal on a typical FDPIR diet compared with a FDPIR diet that met DGA. CONCLUSIONS: Higher energy intake during a typical FDPIR diet compared with a FDPIR diet that meets DGA may increase risk for obesity and nutrition-related diseases, including type 2 diabetes and other chronic inflammatory conditions.

Probiotics and Gut Health in Athletes.

PURPOSE OF REVIEW: To provide a focused analysis of the challenges to gut health in athletes and examine recent research aimed at determining the impact of probiotics on preventing gastrointestinal (GI) symptoms and loss of barrier function in athletes. RECENT FINDINGS: Frequency and severity of GI symptoms during training or competition were reduced by approximately one-third in studies demonstrating efficacy. Improvement of GI symptoms with probiotic supplementation was measured in both single-strain Lactobacillus and multi-strain Lactobacillus and Bifidobacterim probiotics, while improvement in gut barrier function was only measured for multi-strain probiotics. Likelihood of efficacy increased with duration of supplementation. The greatest efficacy for reducing GI symptom frequency and severity, as well as improving or preserving gut barrier function during exercise training and competition, appears to be for multi-strain Lactobacillus and Bifidobacterium probiotic cocktails supplemented for at least 11 weeks.

Sleep, physical activity, waist circumference and diet as factors that influence health for reproductive age women in northern Greenland.

BACKGROUND: This study explored community and individual factors that influence the health of reproductive age women in a settlement in northern Greenland. This is important because Greenland has a declining population, a high abortion rate and because of projected environmental shifts due to climate change. METHODS: This study collected mixed methods data to explore diet, physical activity, sleep and waist circumference for reproductive age women in Kullorsuaq, Greenland. The daily steps and sleeping hours of 13 reproductive age women were measured using activity monitoring bracelets. Waist circumference measurements and in-depth interviews about daily eating and physical activity were conducted with 15 participants and ethnographic participant observations were recorded using field notes. RESULTS: Waist circumference measurements were above recommended cutoffs established by the World Health Organization. Physical activity measured by daily steps was within the 'active' range using the cutoff points established by Tudor and Locke. Physical activity is social and is important for communal relationships. Sleeping hours were within normal ranges based on US guidelines; however, the quality of this sleep, its variability across seasons and cultural expectations of what healthy sleep means must be further explored. Diets of women included a mixture of locally harvested meats and imported packaged foods. Study participants experienced less satiety and reported getting hungrier faster when eating packaged foods. This research took place in Spring 2016 and women reported that their sleep, physical activity and diet fluctuate seasonally. CONCLUSION: The reported findings suggest further investigation of sleep, diet and physical activity combined with the measurement of reproductive hormones to determine linkages between lifestyle factors and reproductive health outcomes is needed.

Dietary Supplements for Health, Adaptation, and Recovery in Athletes.

Some dietary supplements are recommended to athletes based on data that supports improved exercise performance. Other dietary supplements are not ergogenic per se, but may improve health, adaptation to exercise, or recovery from injury, and so could help athletes to train and/or compete more effectively. In this review, we describe several dietary supplements that may improve health, exercise adaptation, or recovery. Creatine monohydrate may improve recovery from and adaptation to intense training, recovery from periods of injury with extreme inactivity, cognitive processing, and reduce severity of or enhance recovery from mild traumatic brain injury (mTBI). Omega 3-fatty acid supplementation may also reduce severity of or enhance recovery from mTBI. Replenishment of vitamin D insufficiency or deficiency will likely improve some aspects of immune, bone, and muscle health. Probiotic supplementation can reduce the incidence, duration, and severity of upper respiratory tract infection, which may indirectly improve training or competitive performance. Preliminary data show that gelatin and/or collagen may improve connective tissue health. Some anti-inflammatory supplements, such as curcumin or tart cherry juice, may reduce inflammation and possibly delayed onset muscle soreness (DOMS). Beta-hydroxy beta-methylbutyrate (HMB) does not consistently increase strength and/or lean mass or reduce markers of muscle damage, but more research on recovery from injury that includes periods of extreme inactivity is needed. Several dietary supplements, including creatine monohydrate, omega 3-fatty acids, vitamin D, probiotics, gelatin, and curcumin/tart cherry juice could help athletes train and/or compete more effectively.

The Grocery Store Food Environment in Northern Greenland and Its Implications for the Health of Reproductive Age Women.

The population of Greenland is diminishing and environmental and social shifts implicate food availability and the health of reproductive age women. There is little knowledge of the grocery store food environment in Greenland. To address this gap and provide baseline information the present study measured food availability in five grocery stores in northern Greenland. As well, 15 interviews were conducted with reproductive age women, three grocery store managers were interviewed and one interview was conducted with a food distribution manager. Results show few fresh fruits and vegetables are available in grocery stores and in some stores no fresh foods are available. In Kullorsuaq, the primary location for this study, the Nutrition Environment Measures Survey in Stores score in spring 2016 was (3/30) and the Freedman Grocery Store Survey Score was (11/49). Interview results highlight a need to increase communication within the food system and to tailor food distribution policies to the Arctic context with longer term planning protocols for food distribution. These findings can be used to inform future food store environment research in Greenland and for informing policies that improve healthful food availability in grocery stores in northern Greenland.

Physical Activity and Adiposity-related Inflammation: The MESA.

PURPOSE: Physical activity is associated with decreased adiposity-related inflammation in adults. Whether this association is independent of central obesity is unknown but important for understanding the mechanisms associated with reducing cardiometabolic disease risk through physical activity. This study examined whether associations of physical activity and obesity-related inflammatory markers were independent of central adiposity. METHODS: Between 2002 and 2005, 1970 participants from the Multi-Ethnic Study of Atherosclerosis completed detailed health history and physical activity questionnaires, underwent physical measurements including computed tomography to quantify abdominal visceral and subcutaneous fat, and measurements of adiponectin, leptin, interleukin-6, tumor necrosis factor-alpha, and resistin. Statistical analyses included analysis of covariance and multivariable-adjusted regression. RESULTS: The mean (range) age of participants was 64.7 (55-84) yr and 50% were women. After adjustment for age and sex, and compared with the lowest quartile, inflammatory markers in the highest quartile of moderate-to-vigorous physical activity were 16% higher for adiponectin and 30%, 26%, and 9% lower for leptin, interleukin-6, and resistin, respectively (P < 0.05 for all). In linear regression adjusted for demographics, dyslipidemia, hypertension, diabetes, smoking, glomerular filtration rate, renin, and aldosterone, each standard deviation increment of moderate-to-vigorous physical activity was associated with significantly higher levels of adiponectin (ß = 0.04) and lower levels of leptin (ß = -0.06), interleukin-6 (ß = -0.08), and resistin (ß = -0.05, P < 0.05 for all). The associations with leptin, interleukin-6, and resistin were independent of total and central adiposity (P < 0.05), whereas the association between moderate-to-vigorous physical activity and adiponectin was attenuated by central adiposity (P > 0.05). There were no significant interactions by race/ethnicity or sex. CONCLUSIONS: Moderate-to-vigorous physical activity was associated with a more favorable profile of inflammatory markers, independent of relevant cardiometabolic disease risk factors including central obesity.

Concentric and eccentric exercise, glycemic responses to a postexercise meal, and inflammation in women with high versus low waist circumference.

Carbohydrate ingestion and level of concentric versus eccentric muscle activity may alter exercise-induced health benefits for individuals who have high waist circumference as a metabolic risk factor. The purpose of this study was to determine whether metabolic and inflammation responses to an exercise recovery meal differ between women with lower (Lo-WC, <80 cm) compared with higher (Hi-WC) waist circumference when the exercise is primarily concentric (uphill walking; UPHILL) versus primarily eccentric (downhill walking; DOWNHILL). Recreationally active women (age, 18-39 years; body mass index, 19-35.4 m·kg-2; Lo-WC, n = 13; Hi-WC, n = 10) completed UPHILL, DOWNHILL, and resting (CONTROL) conditions followed 30 min later by a mixed meal tolerance test (MMTT) with carbohydrates to protein ratio of 4:1, and blood glucose, insulin, and inflammation markers were compared across conditions. Compared with Lo-WC, the Hi-WC group had higher (p < 0.05) (i) insulin during the MMTT in CONTROL (mean ± SE; 48.5 ± 8.2 vs 22.9 ± 2.8 pmol·L-1), (ii) baseline (0.7 ± 0.4 vs 2.0 ± 1.7 pg·mL-1) interleukin-6 (IL-6), and (iii) IL-6 responses 8 h after UPHILL and CONTROL. Both groups had (i) increases in IL-6 at 0 h after UPHILL and at 8 h after DOWNHILL, and (ii) lower glycemic responses in UPHILL. Women with Hi-WC had higher IL-6 at rest and delayed increases in IL-6 after a high-carbohydrate meal in all conditions. This is consistent with an inflammation response to the meal and or uphill walking exercise. However, both concentrically and eccentrically biased exercises offered benefits to insulin responses to a high carbohydrate meal for Hi-WC.

Hyperleptinemia is associated with CRP, but not apolipoprotein E, and is reduced by exercise training.

The purpose of this study was to examine whether leptin levels affect the response of leptin to exercise training (ET) and whether this is also affected by C-reactive protein (CRP) or the three common Apolipoprotein E genotypes (APOE). Ninety-seven (male = 45, female = 52) sedentary individuals underwent 6 months of supervised ET. Blood was sampled before the initiation of ET, and again 24 and 72 hr after completion of the final training session. ET resulted in a small reduction in body mass (80.47 ± 18.03 vs 79.42 ± 17.34 kg, p < .01). Leptin was reduced 24 hr after the final exercise session (p < .01), but returned to normal after 72 hr (p > .05)--Pre: 13.51 ± 12.27, 24hr: 12.14 ± 12.34, 72 hr: 12.98 ± 11.40 ng/ml. The most hyperleptinemic individuals had a greater initial response, which was sustained through to 72 hr after the final session in the pooled study population (p < .01), and in both males (p < .05) and females (p < .05) separately. CRP was related to leptin independently of body weight and positively related to the reductions in leptin. APOE genotype was not related to leptin levels and did not affect the response to ET. Leptin levels may only be reduced by ET in those with hyperleptinemia. In addition, both the initial extent of hyperleptinemia and the subsequent reduction in leptin may be related to low grade chronic systemic inflammation.

Dietary, anthropometric, blood-lipid, and performance patterns of American College Football Players during 8 weeks of training.

PURPOSE: 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.

Basal, circadian, and acute inflammation in normal versus overweight men.

UNLABELLED: 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 ≤25 kg·m, n = 20) and overweight (body mass index = 25-30 kg·m, n = 10) completed exercise (EX) and control (CON) conditions in random order. Maximal voluntary effort and eccentric actions (3 × 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 - 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). 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.

Interactive effects of APOE haplotype, sex, and exercise on postheparin plasma lipase activities.

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 µmol 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.

Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain.

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) or placebo (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 supplementation (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.

Enhanced inflammation with high carbohydrate intake during recovery from eccentric exercise.

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-alpha, interleukin (IL)-1beta, 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-1beta 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.

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)-1ß 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-ß-cell function increased 23 hours postexercise in both conditions, whereas IL-1ß 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-1ß 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.