Search Results

You are looking at 81 - 90 of 279 items for :

Clear All
Restricted access

Allan H. Goldfarb, Changmo Cho, Hojune Cho, Brett Romano-Ely and M. Kent Todd

The purpose of this study was to determine whether an isocaloric beverage with added protein and vitamins (CHOPA) would influence oxidative stress and inflammation after cycling to exhaustion as indicated by plasma protein carbonyls (PC), lipid hydroperoxides (LOOH), and interleukin-6 (IL-6). Twelve trained men (18–33 yr) volunteered and performed this randomized crossover study. Participants cycled at 70% VO2peak until fatigue and at 80% VO2peak 22–24 hr later to fatigue with either carbohydrate or CHOPA. Blood collected before the cycling at rest and 24, 48, and 72 hr after the exercise was analyzed for PC and LOOH spectrophotometrically and for IL-6 via an enzyme-linked immunosorbent assay. The data were analyzed with SPSS using repeated-measures ANOVA. PC demonstrated significant treatment (p = .037) and time (p = .004) effects with no Treatment × Time interaction. PC was higher in the CHOPA treatment than with CHO independent of time and increased at 24 (48%), 48 (59%), and 72 (67%) hr after exercise compared with preexercise values. Resting LOOH and IL-6 did not have any significant changes with time or treatment. These data indicate that an isocaloric CHOPA drink after 2 cycling bouts to exhaustion will exacerbate the resting PC level compared with an isocaloric drink, with no influence on plasma LOOH or IL-6. In addition, a modest significant increase in PC over time independent of treatment occurred, which suggests a mild oxidative stress in the days after exhaustive exercise.

Restricted access

Marc T. Hamilton, Enas Areiqat, Deborah G. Hamilton and Lionel Bey

Physical activity often declines with age because of a reduction in the spontaneous activities of daily living and because of less intense exercise. In controlled studies of young rats, it was shown that physical activities associated with walking and standing were especially important for maintaining a high level of lipoprotein lipase (LPL) activity in postural skeletal muscles (slowtwitch oxidative muscles). More intense contractions during run training were important for a high LPL activity in the fast-twitch glycolytic muscles. Aging also causes a fiber type–specific decrease of skeletal muscle LPL activity and LPL protein in weight-bearing skeletal muscles (and no aging effect in glycolytic muscles). Thus, contractile inactivity may be a significant factor causing sub-optimal triglyceride metabolism in skeletal muscles during both unloading in young animals and aging. Measurements of plasma LPL activity, plasma triglyceride (TG) clearance rates, postprandial hypertriglyceridemia after oral fat tolerance tests, and fasting TG levels were generally indicative of reduced plasma TG metabolism during middle or old age. In contrast, older endurance-trained individuals had a favorable blood lipid profile compared to age-matched or young controls, even when the controls were not overweight. Therefore, the poor TG metabolism that is frequently associated with aging may be caused by some of the same processes that lower skeletal muscle LPL activity of young sedentary individuals.

Restricted access

Vitor Teixeira, Hugo Valente, Susana Casal, Franklim Marques and Pedro Moreira

Strenuous physical activity is known to generate reactive oxygen species to a point that can exceed the antioxidant defense system and lead to oxidative stress. Dietary intake of antioxidants, plasma enzymatic (superoxide dismutase, glutathione reductase [Gr], and glutathione peroxidase [GPx]) activities, nonenzymatic (total antioxidant status [TAS], uric acid, α-tocopherol, retinol, α-carotene, β-carotene, lycopene, and lutein + zeaxanthin) antioxidants, and markers of lipid peroxidation (thiobarbituricacid-reactive substances [TBARS]) and muscle damage (creatine kinase [CK]) were measured in 17 elite male kayakers and canoeists under resting conditions and in an equal number of age- and sex-matched sedentary individuals. Athletes showed increased plasma values of α-tocopherol (p = .037), α-carotene (p = .003), β-carotene (p = .007), and superoxide dismutase activity (p = .002) and a lower TAS level (p = .030). Antioxidant intake (α-tocopherol, vitamin C, and β-carotene) and plasmatic GPx, Gr, lycopene, lutein + zeaxanthin, retinol, and uric acid levels were similar in both groups. Nevertheless, TBARS (p < .001) and CK (p = .011) levels were found to be significantly higher in the kayakers and canoeists. This work suggests that despite the enhanced levels of antioxidants, athletes undergoing regular strenuous exercise exhibited more oxidative stress than sedentary controls.

Restricted access

Sonia Vega-López, Giselle A.P. Pignotti, Colleen Keller, Michael Todd, Barbara Ainsworth, Allison Nagle Williams, Kathie Records, Dean Coonrod and Paska Permana

Background:

The effects of moderate intensity walking on lipoprotein remodeling in postpartum Hispanic women are unknown.

Methods:

Sedentary postpartum Hispanic women (28.2 ± 5.6 y; BMI = 29.3 ± 3.3 kg/m2) participating in a social support physical activity (PA) intervention, were randomly assigned to a 12-month walking program (walkers; n = 22; target 150 min/wk, moderate intensity) or a control group (nonwalkers; n = 22). Fasting lipids and cholesterol distribution within low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles were measured at baseline (BL), 6 months, and 12 months.

Results:

Walkers had an 11% increase and nonwalkers a 7% decrease in HDL cholesterol from 6 to 12 months (P = .0367) without an effect on LDL cholesterol. Whereas nonwalkers had virtually no change in mean LDL particle size, walkers had a borderline reduction in LDL size from BL (268.7 ± 4.1 Å) to 6 months (266.9 ± 4.9 Å), followed by a significant increase in size by 12 months (269.7 ± 4.1 Å; P = .011). The proportion of cholesterol in large LDL particles decreased by 15% from BL to 6 months, but subsequently increased 25% by 12 months among walkers; changes among nonwalkers were smaller and in opposite direction (4% and –3%, respectively; P = .0004).

Conclusions:

Participation in the social-support PA intervention resulted in slightly increased HDL cholesterol concentrations and a modest and beneficial shift toward larger, less atherogenic LDL particles.

Restricted access

Arlette C. Perry, Linda S. Crane, Brooks Applegate, Sylvia Marquez-Sterling, Joseph F. Signorile and Paul C. Miller

The present study showed that amenorrheic athletes (AAs) scored higher on the Eating Attitudes Test (EAT) (p < .05) than eumenorrheic athletes (EAs), indicating more aberrant eating patterns in the first group. Scores on the EAT were inversely correlated with fat intake (p < .05), simple carbohydrate intake (p < .01), and percentage saturation of iron (p < .05) and were positively correlated with total iron binding capacity (p < .01) for the total sample. Physiological assessment of athletes revealed that there were no significant differences between groups in serum lipoproteins, with both EAs and AAs having serum lipid profiles indicative of low cardiovascular risk. Furthermore, low-density lipoprotein cholesterol was the only lipoprotein significantly and positively correlated with serum estradiol levels for the entire sample (p = .01). The present study was in agreement with previous work showing that scores on the EAT represent a primary difference between EAs and AAs; the present study was somewhat different than previous work in that serum lipoproteins were not significantly related to menstrual status.

Restricted access

Steven Couture, Benoit Lamarche, Eliane Morissette, Veronique Provencher, Pierre Valois, Claude Goulet and Vicky Drapeau

The objectives of this study were to evaluate high school coaches’ knowledge in sports nutrition and the nutritional practices they recommend to their athletes. Forty-seven high school coaches in “leanness” and “non-leanness” sports from the greater region of Quebec (women = 44.7%) completed a questionnaire on nutritional knowledge and practices. “Leanness sports” were defined as sports where leanness or/and low bodyweight were considered important (e.g., cheerleading, swimming and gymnastics), and “non-leanness sports” were defined as sports where these factors are less important (e.g., football). Participants obtained a total mean score of 68.4% for the nutrition knowledge part of the questionnaire. More specifically, less than 30% of the coaches could answer correctly some general nutrition questions regarding carbohydrates and lipids. No significant difference in nutrition knowledge was observed between coaches from “leanness” and “non-leanness” sports or between men and women. Respondents with a university education scored higher than the others (73.3% vs. 63.3%, p < .05). Coaches who participated in coaching certification also obtained better results than those without a coaching certification. The most popular source of information about nutrition used by coaches was the Internet at 55%. The two most popular nutrition practices that coaches recommended to improve athlete performance were hydration and consumption of protein-rich foods. Recommendation for nutritional supplements use was extremely rare and was suggested only by football coaches, a nonleanness sport. Findings from this study indicate that coaches need sports nutrition education and specific training.

Restricted access

James D. LeCheminant, Larry A. Tucker, Bruce W. Bailey and Travis Peterson

Purpose:

To determine objectively measured intensity of physical activity (iPA) and its relationship to high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and the LDL/HDL ratio in women.

Methods:

Two hundred seventy-two women (40.1 y) wore CSA-MTI model 7164 accelerometers to index intensity and volume of physical activity for 7 d. Blood lipids were measured at a certified laboratory.

Results:

HDL-C was 52.1 ± 10.1, 52.2 ± 9.7, and 56.1 ± 11.1 mg/dL for the low, medium, and high intensity groups (P = 0.040), LDL-C differences were not significant (P = 0.23). LDL/HDL differences were observed (P = 0.030) with specific differences between the low and high iPA groups (P = 0.006). For HDL-C and LDL/HDL, significant relationships remained with control of dietary fat and age but not body fat percentage or volume of activity.

Conclusions:

High iPA had higher HDL-C levels and lower LDL/HDL ratios than low and medium iPA. The iPA was predictive of HDL-C partly due to its strong association with volume of activity and body fat percentage.

Restricted access

Wendy Hens, Jan Taeymans, Justien Cornelis, Jan Gielen, Luc Van Gaal and Dirk Vissers

Background:

Reduction of ectopic fat accumulation plays an important role in the prevention of insulin resistance in people with overweight or obesity. This systematic review and meta-analysis summarizes the current evidence for the use of noninvasive weight loss interventions (exercise or diet) on ectopic fat.

Methods:

A systematic literature search was performed according to the PRISMA statement. Clinical trials in PubMed, PEDro, and the Cochrane database were searched.

Results:

All 33 included studies described the effect of lifestyle interventions on ectopic fat storage in internal organs (liver, heart, and pancreas) and intramyocellular lipids (IMCL), hereby including 1146, 157, 87, and 336 participants. Overall, a significant decrease of ectopic fat was found in liver (−0.53 Hedges’ g, P < .001), heart (−0.72 Hedges’ g, P < .001) and pancreas (–0.55 Hedges’ g, P = .098) respectively. A trend toward decrease in IMCL was also observed. Meta-regression indicated a dose-response relationship between BMI reduction and decreased hepatic adiposity. Exercise alone decreased ectopic fat but the effect was greater when combined with diet.

Conclusions:

Lifestyle interventions can reduce ectopic fat accumulation in the internal organs of overweight and obese adults. The results on IMCL should be interpreted with care, keeping the ‘athlete’s paradox’ in mind.

Restricted access

Rudolph G. Villani, Jenelle Gannon, Megan Self and Peter A. Rich

L-Carnitine (L-C) transports fatty acids into mitochondria for oxidation and is marketed as a weight loss supplement. In a double-blind investigation to test the weight loss efficacy of L-C, 36 moderately overweight premenopausal women were pair matched on Body Mass Index (BMI) and randomly assigned to two groups (N = 18). For 8 weeks the L-C group ingested 2 g twice daily of L-C, while the placebo (P) group ingested the same amount of lactose. All subjects walked for 30 min (60—70% maximum heart rate) 4 days/ week. Body composition, resting energy expenditure (REE) and substrate utilization were estimated before and after treatment. For the subjects who completed the study (15 P, 13 L-C), no significant changes in mean total body mass (TBM), fat mass FM, and resting lipid utilization occurred over time, nor were there any significant differences between groups for any variable. Conversely REE increased significantly for all subjects, but no between group differences existed. Five of the L-C group experienced nausea or diarrhea and consequently did not complete the study. Eight weeks of L-C ingestion and walking did not significantly alter the TBM or FM of overweight women, thereby casting doubt on the efficacy of L-C supplementation for weight loss.

Restricted access

James H. Rimmer, David Braddock and Glenn Fujiura

A body mass index (BMI) greater than 27 has been cited as a risk factor for heart disease and diabetes mellitus resulting from excess weight. The purpose of this study was to determine the association between BMI (>27) and two other obesity indices–height-weight and percent body fat–as well as to investigate the relationship between BMI and three blood lipid parameters–total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in 329 adults with mental retardation (MR). Males were significantly taller and heavier than females, but females had a significantly higher BMI. Kendall’s Tau-C revealed a significant association between BMI and each of the following: height-weight, percent body fat, LDL-C, and HDL-C. However, there were a significant number of false negatives and false positives on each of the criteria. The congruence between at-risk BMI and two other obesity parameters (height-weight and percent body fat) in a population of adults with MR is not strong. Professionals should employ the BMI along with skinfold measures to assess a person’s at-risk status for excess weight.