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Mary O. Hearst, John R. Sirard, Leslie Lytle, Donald R. Dengel and David Berrigan

Background:

The association of physical activity (PA), measured 3 ways, and biomarkers were compared in a sample of adolescents.

Methods:

PA data were collected on 2 cohorts of adolescents (N = 700) in the Twin Cities, Minnesota, 2007–2008. PA was measured using 2 survey questions [Modified Activity Questionnaire (MAQ)], the 3-Day Physical Activity Recall (3DPAR), and accelerometers. Biomarkers included systolic (SBP) and diastolic blood pressure (DBP), lipids, percent body fat (%BF), and body mass index (BMI) percentile. Bivariate relationships among PA measures and biomarkers were examined followed by generalized estimating equations for multivariate analysis.

Results:

The 3 measures were significantly correlated with each other (r = .22–.36, P < .001). Controlling for study, puberty, age, and gender, all 3 PA measures were associated with %BF (MAQ = −1.93, P < .001; 3DPAR = −1.64, P < .001; accelerometer = −1.06, P = .001). The MAQ and accelerometers were negatively associated with BMI percentile. None of the 3 PA measures were significantly associated with SBP or lipids. The percentage of adolescents meeting the national PA recommendations varied by instrument.

Conclusions:

All 3 instruments demonstrated consistent findings when estimating associations with %BF, but were different for prevalence estimates. Researchers must carefully consider the intended use of PA data when choosing a measurement instrument.

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Katy Horner, Emma Barinas-Mitchell, Curt DeGroff, Jennifer L. Kuk, Stacey Drant and SoJung Lee

A cardiovascular comorbidity in obese adolescents is increased aortic pulse wave velocity (aPWV), carotid intima-media thickness (cIMT) and left ventricular mass (LVM). We investigated in obese adolescents 1) the risk factors associated with aPWV, cIMT and LVM, and 2) the effects of aerobic (AE) versus resistance (RE) exercise alone (without calorie restriction) on aPWV, cIMT, LVM index (LVMI) and cardiometabolic risk factors. Eighty-one obese adolescents (12–18 yrs, BMI ≥95th percentile) were randomized to 3 months of AE (n = 30), RE (n = 27) or a control group (n = 24). Outcome measures included aPWV, cIMT, LVMI, body composition, cardiorespiratory fitness (CRF), blood pressure (BP) and lipids. At baseline, the strongest correlates of aPWV were body weight (r = .31) and diastolic BP (r = .28); of cIMT were body weight (r=0.26) and CRF (r=-0.25); and of LVMI was CRF (r=0.32) after adjusting for sex and race (p < .05 for all). Despite significant reductions in total fat and improvements in CRF in the AE and RE groups, aPWV, cIMT, LVMI, BP, lipids and body weight did not change as compared with controls (p > .05 for all). Interventions of longer duration or together with weight loss may be required to improve these early biomarkers of CVD in obese adolescents.

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Jason T. Penry and Melinda M. Manore

Choline plays a central role in many physiological pathways, including neurotransmitter synthesis (acetylcholine), cell-membrane signaling (phospholipids), lipid transport (lipoproteins), and methyl-group metabolism (homocysteine reduction). Endurance exercise might stress several of these pathways, increasing the demand for choline as a metabolic substrate. This review examines the current literature linking endurance exercise and choline demand in the human body. Also reviewed are the mechanisms by which exercise might affect blood choline levels, and the links between methyl metabolism and the availability of free choline are highlighted. Finally, the ability of oral choline supplements to augment endurance performance is assessed. Most individuals consume adequate amounts of choline, although there is evidence that current recommendations might be insufficient for some adult men. Only strenuous and prolonged physical activity appears sufficient to significantly decrease circulating choline stores. Moreover, oral choline supplementation might only increase endurance performance in activities that reduce circulating choline levels below normal.

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Mitchell M. Kanter and Melvin H. Williams

Three nutritional products that have very different mechanisms of action are antioxidant vitamins, carnitine, and choline. Antioxidant vitamins do not appear to have a direct effect on physical performance in well-fed people but have been touted for their ability to detoxify potentially damaging free radicals produced during exercise. Carnitine purportedly enhances lipid oxidation, increases VO2max, and decreases plasma lactate accumulation during exercise. However, studies of carnitine do not generally support its use for ergogenic purposes. Choline supplements have been advocated as a means of preventing the decline in acetylcholine production purported to occur during exercise; this decline may reduce the transmission of contraction-generating impulses across the skeletal muscle, an effect that could impair one’s ability to perform muscular work. However, there are no definitive studies in humans that justify choline supplementation. Much of the scientific data regarding the aforementioned nutrients are equivocal and contradictory. Their potential efficacy for improving physical performance remains largely theoretical.

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Robert E. Keith, Michael H. Stone, Ralph E. Carson, Robert G. Lefavi and Steven J. Fleck

Fourteen trained male anabolic steroid-using bodybuilders (SBBs) (19-41 years) were recruited for the study. Three-day diet records were obtained from SBBs and analyzed. A resting venous blood sample was drawn, and serum/ plasma was subsequently analyzed for various nutritionally related factors. Results showed that mean dietary energy (4,469 ± 1,406 kcal), protein (252 ± 109 g), and vitamin and mineral intakes of SBBs greatly exceeded U.S. Recommended Dietary Allowances. Dietary cholesterol intake was 2.8 times the recommended levels. Mean serum/plasma nutrient concentrations of SBBs were within normal range. However, individual SBBs had a number of serum/ plasma values outside of the normal or recommended range, the most notable of which was hypercalcemia, which was present in 42% of SBBs. Serum/plasma lipids were such as to increase the risk of cardiovascular disease in these subjects.

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Andrea Di Blasio, Pascal Izzicupo, Emanuele D’Angelo, Sandra Melanzi, Ines Bucci, Sabina Gallina, Angela Di Baldassarre and Giorgio Napolitano

Purpose:

High-intensity aerobic interval training (AIT) has been reported to be more effective than continuous aerobic training (CoAT) to improve metabolic health. The aim of our study was to investigate whether moderate-intensity AIT is more effective than CoAT on metabolic health when applied to a walking training program.

Design/Methods:

Thirty-two postmenopausal women (55.37 ± 3.46 years) were investigated for body composition, plasma glucose, insulin, lipids, adiponectin, HOMA-IR, HOMA-AD, aerobic fitness, dietary habits, and spontaneous physical activity, and randomly assigned to one of two different walking training programs: CoAT or AIT.

Results:

CoAT and AIT elicited the same physiological benefits, including: reduction of plasma glucose, insulin, HOMA-IR and HOMA-AD, and increase of plasma HDL-C, adiponectin, and aerobic fitness.

Conclusions:

An AIT scheme as part of an outdoor walking training program elicits the same physiological adaptations as a CoAT scheme, probably because walking does not promote exercise intensities that elicit greater effects.

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Hui Ying Wu, Jui Hung Tu, Chin Hsing Hsu and Te Hung Tsao

The effect of low-impact dance on blood metabolites, the joint range of motion (ROM) of the lower extremities, knee extension torque, bone mass density (BMD), the number of falls, and the confidence to perform daily activities (Modified Falls Efficacy Scale [MFES]) was examined in older sedentary women (age: 59 ± 4 years) before and after a 16-week intervention. Results showed that the average score for the MFES, some parameters of blood chemistry, and joint ROM were significantly improved after low-impact intervention. In addition to improvements in blood lipids and body fat percentages, the increases shown in the parameters regarding the lower extremities may contribute to confidence in performing common daily activities in older women, although the number of falls did not significantly differ between the two groups during the 16-week period.

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Ro DiBrezzo, Barbara B. Shadden, Blake H. Raybon and Melissa Powers

Loss of balance and falling are critical concerns for older adults. Physical activity can improve balance and decrease the risk of falling. The purpose of this study was to evaluate a simple, low-cost exercise program for community-dwelling older adults. Sixteen senior adults were evaluated using the Senior Fitness Test for measures of functional strength, aerobic endurance, dynamic balance and agility, and flexibility. In addition, measures of height, weight, resting blood pressure, blood lipids, and cognitive function were obtained. Participants then attended a 10-week exercise class including stretching, strengthening, and balance-training exercises. At the completion of the program, significant improvements were observed in tests measuring dynamic balance and agility, lower and upper extremity strength, and upper extremity flexibility. The results indicate that exercise programs such as this are an effective, low-cost solution to improving health and factors that affect falling risk among older adults.

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Hye-Ryun Hong, Jin-Kyung Cho, Ji-Young Lee, Jin-Koo Park and Hyun-Sik Kang

The present study investigated the relationships among metabolic risk factors, major lifestyle factors, and serum cytokines in a sample of Korean children. In a cross-sectional design, we studied a total of 275 children (130 boys and 145 girls) aged 12–13 years. Measured variables included anthropometrics, blood pressures (BP), VO2max, physical activity (PA), dietary intakes, lipids, glucose, and insulin. We explored the extent to which dietary intakes, VO2max, PA, and serum cytokines explained variance in a clustered risk score, which is a sum of Z scores for waist circumference, BP, TG, HDLC, and HOMA-IR, using a stepwise linear regression by blocks. VO2max, vigorous PA (VPA), and leptin were independent predictors for the clustered risk score while adjusting for age and Tanner stage. Our findings suggest that the clustered risk score is associated not only with low levels of VO2max and VPA, but also with elevated serum leptin in Korean children.

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Alpay Cakmak, Dost Zeyrek, Ali Atas and Ozcan Erel

Regular physical activity may play a protective role against cardiovascular disease in adults, and paraoxonase activity may serve to mediate this effect. This study compared paraoxonase activity and that of other antioxidative agents in adolescent athletes compared with inactive youth. Paraoxonase level was 177.32 ± 100.10 (U/L) in children with regular physical activity and 98.11 ± 40.92 (U/L) in the control group (P < 0.0001). The levels of total antioxidative capacity, total oxidative status, oxidative stress index, and lipid hydroperoxide were significantly higher in the athlete group compared with controls (P < 0.0001). Paraoxonase activity was found to be greater in adolescent athletes, suggesting that regular exercise might provide a cardio-protective effect by this means.