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Ya-Wen Hsu, Chih-Ping Chou, Britni R. Belcher, Selena T. Nguyen-Rodriguez, Marc J. Weigensberg, Arianna D. McClain and Donna Spruijt-Metz

While most studies have focused on investigating the preventive effects of physical activity on metabolic risk, the longitudinal impacts of metabolic syndrome (MetS) on activity levels is poorly understood. This study aims to examine the influence of MetS on initial activity levels and the trajectory of activity levels in Latina and African American female children over 12 months (n = 55, 9 ± 1 years). Metabolic measures, including fat and lean tissue mass by BodPod, fasting glucose, lipids, blood pressure, and waist circumference, were collected at baseline. Moderate-to-vigorous physical activity and sedentary behavior by accelerometry were collected on a quarterly basis. There were no significant differences in either initial activity levels by MetS status (Moderate-to-vigorous physical activity: 33 ± 12 mins/day for MetS, 48 ± 28 mins/day for Non-MetS, p = .12; sedentary behavior: 408 ± 57 mins/day for MetS, 421 ± 72 mins/day for Non-MetS, p = .67). Longitudinal declines in moderate-to-vigorous physical activity (p = .038) and increases in sedentary behavior (p = .003) were found. Daily sedentary behavior increased by 82.64 more minutes in youth with MetS than in those without over one year (p = .015). This study yields the first evidence of the adverse effect of MetS on sedentary behavior. Targeted intervention strategies to reduce progressive sedentariness evident in minority youth with MetS are warranted.

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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.

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Kamal Azizbeigi, Mohammad Ali Azarbayjani, Maghsoud Peeri, Hamid Agha-alinejad and Stephen Stannard

This study was undertaken to investigate the effects of progressive resistance-training (PRT) on plasma oxidative stress and antioxidant enzyme activity in erythrocytes. Twenty male volunteers were randomly assigned to 2 groups: PRT and control. Blood samples were collected before and after 8 wk of PRT and analyzed for enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in erythrocytes, plasma total antioxidant capacity (TAC), and malondialdehyde concentration (MDA, an index of lipid per oxidation in plasma). Resistance training commenced with 8 exercises on nonconsecutive days for 8 wk at 50% of estimated 1-repetition maximum (E1RM) and reached 80% E1RM by Week 8. The results showed that PRT significantly increased erythrocyte SOD activity (1,323 ± 212.52 vs. 1,449.9 ± 173.8 U/g Hb, p = .014). Plasma concentration of MDA also decreased (5.39 ± 1.7 vs. 3.67.4 ± 0.7 nmol/ml, p = .030), although TAC (1.42 ± 0.21 vs. 1.61 ± 0.19 mmol/L, p = .1530) and GPx (39.87 ± 11.5 vs. 48.18 ± 14.48 U/g Hb, p = .883) activity did not undergo any considerable changes. Based on these data, the authors conclude that an 8-wk program of PRT strengthens the defensive system of erythrocytes against free-radical damage and therefore can be applied as a useful approach to alleviate oxidative stress.

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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.

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Marco Malaguti, Marta Baldini, Cristina Angeloni, Pierluigi Biagi and Silvana Hrelia

The authors evaluated the role of a high-protein, low-calorie, polyunsaturated fatty-acid (PUFA) -supplemented diet on anthropometric parameters, erythrocytemembrane fatty-acid composition, and plasma antioxidant defenses of nonprofessional volleyball athletes. The athletes were divided in two groups: One (n = 5) followed the Mediterranean diet, and the other (n = 6) followed a high-protein, low-calorie diet with a 3-g/day fish-oil supplementation. All the athletes had anthropometric measurements taken, both at the beginning and at the end of the study, which lasted for 2 months. Body-mass index and total body fat were significantly diminished in the second group, while they remained unchanged in the first. Plasma total antioxidant activity (TAA) was significantly increased in the plasma of both groups, with no differences between the groups, suggesting that physical activity, not the different diets, is the main contributor to the increase of plasma TAA. The second group showed a significant increase in erythrocytemembrane PUFA content and in the unsaturation index value (UI) because of the fish-oil supplementation. A high-protein, low-carbohydrate, fish-oil-supplemented diet seems to be useful only when the aim of the diet is to obtain weight loss in a short-term period. The significant increase in the UI of erythrocyte membranes indicates the potential for harm, because a high intake of PUFA might increase susceptibility to lipid peroxidation not counterbalanced by a higher increase in TAA. Adherence to the Mediterranean diet seems to be the better choice.

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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.

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Joel B. Mitchell, James R. Rowe, Meena Shah, James J. Barbee, Austen M Watkins, Chad Stephens and Steve Simmons

To examine the effect of prior exercise on the postprandial lipid response to a high-carbohydrate meal in normal-weight (NW = BMI h25) and overweight (OW = BMI ≥25) women (age 18–25), 10 NW and 10 OW participants completed 2 conditions separated by 1 month. In the morning, the day after control (CT = no exercise) or exercise conditions (EX = 60 min cycling at 60% VO2peak), participants consumed a high-carbohydrate meal (80% CHO, 15% protein, 5% fat; 75 kJ/kg BM) followed by 6 hr of hourly blood sampling. Blood was analyzed for triglycerides (TG), blood glucose (BG), and insulin (IN). TG levels over the 6-hr period were lower in NW than OW (p = .021) and lower in EX than in CT (p = .006). Area under the curve (AUC) for TG was lower in NW than OW (p = .016) and EX than CT (p = .003). There were nonsignificant tendencies for reduced BG over time (p = .053) and AUC (p = .083), and IN AUC was lower in EX than in CT (p = .040) for both groups and lower in NW than in OW (p = .039). Prior exercise improved TG levels after a high-carbohydrate meal in both groups, and OW women demonstrated a greater postprandial lipemic response than NW regardless of condition. There were tendencies for improved glucose removal with prior exercise in NW vs. OW. Acute exercise can improve postprandial TG responses and might also improve postprandial BG and IN after a large meal in NW and OW young women.

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Paulo Farinatti, Silvio Rodrigues Marques Neto, Ingrid Dias, Felipe A. Cunha, Eliete Bouskela and Luiz G. Kraemer-Aguiar

Purpose:

Cardiac autonomic dysfunction (CADysf) in children is often associated to obesity and may be attenuated by physical activity. In this study, we investigated the effects of resistance training (RT) upon CADysf assessed by heart rate variability (HRV) in obese adolescents.

Method:

Volunteers were assigned into groups according to standard deviation scores for body mass index (z-BMI) and percentile for age and sex: obese (OB; z-BMI from 2 to 3 and ≥ 95th percentile, n = 24) and normal weight controls (CG; z-BMI from -2–1 and < 85th percentile, n = 20). OB performed isolated RT during 12 weeks [3 sets of 6–10reps with 70–85% 10RM]. Waist circumference, systolic/diastolic blood pressures (SBP/DBP), lipids, and HRV were assessed at baseline. Only OB underwent postintervention assessments.

Results:

At baseline, SBP (122.4 ± 9.1 vs. 109.7 ± 11.5 mmHg, p < .001) and DBP (76.1 ± 7.1 vs. 65.3 ± 5.9 mmHg, p < .001) were higher, while parasympathetic HRV indexes were lower (p < .05) in OB compared with CG. After RT, waist circumference (3%, p < .001) and SBP (10%, p < .001) reduced in OB. Parasympathetic indexes of HRV increased in OB (SDNN: 25%, p = .03; rMSSD: 48%, p = .0006; pNN50: 67%, p = .001; total power: 54%, p = .01; HF: 101%, p = .001) and baseline differences between groups for sympathetic and parasympathetic activities were no longer observed after RT.

Conclusion:

RT attenuated CAdyfs and BP in obese adolescents, by increasing parasympathetic activity and decreasing sympatho-vagal balance.

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Ildus I. Ahmetov, Olga L. Vinogradova and Alun G. Williams

The ability to perform aerobic or anaerobic exercise varies widely among individuals, partially depending on their muscle-fiber composition. Variability in the proportion of skeletal-muscle fiber types may also explain marked differences in aspects of certain chronic disease states including obesity, insulin resistance, and hypertension. In untrained individuals, the proportion of slow-twitch (Type I) fibers in the vastus lateralis muscle is typically around 50% (range 5–90%), and it is unusual for them to undergo conversion to fast-twitch fibers. It has been suggested that the genetic component for the observed variability in the proportion of Type I fibers in human muscles is on the order of 40–50%, indicating that muscle fiber-type composition is determined by both genotype and environment. This article briefly reviews current progress in the understanding of genetic determinism of fiber-type proportion in human skeletal muscle. Several polymorphisms of genes involved in the calcineurin–NFAT pathway, mitochondrial biogenesis, glucose and lipid metabolism, cytoskeletal function, hypoxia and angiogenesis, and circulatory homeostasis have been associated with fiber-type composition. As muscle is a major contributor to metabolism and physical strength and can readily adapt, it is not surprising that many of these gene variants have been associated with physical performance and athlete status, as well as metabolic and cardiovascular diseases. Genetic variants associated with fiber-type proportions have important implications for our understanding of muscle function in both health and disease.

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Adamasco Cupisti, Claudia D’Alessandro, Silvia Castrogiovanni, Alice Barale and Ester Morelli

This study aims to investigate dietary composition and nutrition knowledge of 60 athlete and 59 non-athlete adolescent females (age, 14-18 years), using a 3-day food recall and a questionnaire on nutrition. The reported daily energy intake was similar in athletes and non-athletes, but less than the recommended and the estimated requirements. In the athletes, the energy supply from breakfast was higher than in the non-athletes (18.5 ± 6.6 vs. 15.0 ± 8.2%, p < .005). Energy intake from carbohydrates was higher (53.6 ± 6.2 vs. 49.8 ± 63%, p < .05) and that from lipids was lower (30.4 ± 5.5 vs. 34.2 ± 5.2%, p < .001) in athletes than in non-athletes. Athletes also showed higher fiber (20.0 ± 5.8 vs. 14.1 ± 4.3 g/day, p < .001). iron (10.6±5.1 vs. 7.5 ± 2.1 mg/day,/7 < .001) and vitamin A (804 ± 500 vs, 612 ± 456 μg/day, p < .05) reported intake than non-athletes. Calcium, iron, and zinc intake were less than 100% RDA in both groups. Athletes gave a slightly higher rate of correct answers on the nutrition knowledge questionnaire (77.6 vs. 71.6%,p < .01) than non-athletes. In conclusion, the overall recalled dietary intake and nutrition knowledge of the studied adolescent females show some misconceptions and nutrient deficiencies, but the results in athletes are quite better man in non-athletes, suggesting a favorable role of sport practice on dietary habits and nutrition knowledge.