ZEMEL, MICHAEL B., JOANNA RICHARDS, ANITA MILSTEAD, AND PETER CAMPBELL. Effects of calcium and dairy on body composition and weight loss in African-American adults. Obes Res. 2005;13:1218 -1225. Objective: Our objective was to determine the effects of dairy consumption on adiposity and body composition in obese African Americans. Research Methods and Procedures:We performed two randomized trials in obese African-American adults. In the first (weight maintenance), 34 subjects were maintained on a low calcium (500 mg/d)/low dairy (Ͻ1 serving/d) or high dairy (1200 mg Ca/d diet including 3 servings of dairy) diet with no change in energy or macronutrient intake for 24 weeks. In the second trial (weight loss), 29 subjects were similarly randomized to the low or high dairy diets and placed on a caloric restriction regimen (Ϫ500 kcal/d). Results: In the first trial, body weight remained stable for both groups throughout the maintenance study. The high dairy diet resulted in decreases in total body fat (2.16 kg, p Ͻ 0.01), trunk fat (1.03 kg, p Ͻ 0.01), insulin (18.7 pM, p Ͻ 0.04), and blood pressure (6.8 mm Hg systolic, p Ͻ 0.01; 4.25 mm Hg diastolic, p Ͻ 0.01) and an increase in lean mass (1.08 kg, p Ͻ 0.04), whereas there were no significant changes in the low dairy group. In the second trial, although both diets produced significant weight and fat loss, weight and fat loss on the high dairy diet were ϳ2-fold higher (p Ͻ 0.01), and loss of lean body mass was markedly reduced (p Ͻ 0.001) compared with the low dairy diet.Discussion: Substitution of calcium-rich foods in isocaloric diets reduced adiposity and improved metabolic profiles in obese African Americans without energy restriction or weight loss and augmented weight and fat loss secondary to energy restriction.

BACKGROUND AND OBJECTIVE:We have previously demonstrated an antiobesity effect of dietary Ca; this is largely mediated by Ca suppression of calcitriol levels, resulting in reduced adipocyte intracellular Ca 2 þ and, consequently, a coordinated increase in lipid utilization and decrease in lipogenesis. Notably, dairy Ca is markedly more effective than other Ca sources. DESIGN: Obese subjects were placed on balanced deficit (À500 kcal/day) diets and randomized to control (400-500 mg Ca/ day; n ¼ 16) or yogurt (1100 mg Ca/day; n ¼ 18) treatments for 12 weeks. Dietary macronutrients and fiber were held constant at the US average. MEASUREMENTS: Body weight, body fat and fat distribution (by dual-energy X-ray absorptiometry), blood pressure and circulating lipids were measured at baseline and after 12 weeks of intervention. RESULTS: Fat loss was markedly increased on the yogurt diet (À4.4370.47 vs À2.7570.73 kg in yogurt and control groups; Po0.005) while lean tissue loss was reduced by 31% on the yogurt diet. Trunk fat loss was augmented by 81% on the yogurt vs control diet (Po0.001), and this was reflected in a markedly greater reduction in waist circumference (À3.9970.48 vs À0.5871.04 cm, Po0.001). Further, the fraction of fat lost from the trunk was higher on the yogurt diet vs control (Po0.005). CONCLUSION: Isocaloric substitution of yogurt for other foods significantly augments fat loss and reduces central adiposity during energy restriction.

Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R 2 = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both 'large' in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.

Whilst the measurement and quantification of vertical leg stiffness (K vert ) asymmetry is of important practical relevance to athletic performance, literature investigating bilateral asymmetry in K vert is limited. Moreover, how the type of task used to assess K vert may affect the expression of asymmetry has not been properly determined. Twelve healthy males performed three types of performance tasks on a dual force plate system to determine K vert asymmetries; the tasks were (a) bilateral hopping, (b) bilateral drop jumping and (c) unilateral drop jumping. Across all the three methods, K vert was significantly different between compliant and stiff limbs (P < 0.001) with a significant interaction effect between limb and method (P = 0.005). Differences in K vert between compliant and stiff limbs were −5.3% (P < 0.001), −21.8% (P = 0.007) and −15.1% (P < 0.001) for the bilateral hopping, bilateral drop jumping and unilateral drop jumping methods, respectively. All the three methods were able to detect significant differences between compliant and stiff limbs, and could be used as a diagnostic tool to assess K vert asymmetry. Drop jumping tasks detected larger K vert asymmetries than hopping, suggesting that asymmetries may be expressed to a greater extent in acyclic, maximal performance tasks.

BackgroundThe athlete’s heart is associated with physiological remodeling as a consequence of repetitive cardiac loading. The effect of exercise training on left ventricular (LV) cardiac strain and twist mechanics are equivocal, and no meta-analysis has been conducted to date.ObjectiveThe objective of this systematic review and meta-analysis was to review the literature pertaining to the effect of different forms of athletic training on cardiac strain and twist mechanics and determine the influence of traditional and contemporary sporting classifications on cardiac strain and twist mechanics.MethodsWe searched PubMed/MEDLINE, Web of Science, and ScienceDirect for controlled studies of aged-matched male participants aged 18–45 years that used two-dimensional (2D) speckle tracking with a defined athlete sporting discipline and a control group not engaged in training programs. Data were extracted independently by two reviewers. Random-effects meta-analyses, subgroup analyses, and meta-regressions were conducted.ResultsOur review included 13 studies with 945 participants (controls n = 355; athletes n = 590). Meta-analyses showed no athlete–control differences in LV strain or twist mechanics. However, moderator analyses showed greater LV twist in high-static low-dynamic athletes (d = –0.76, 95% confidence interval [CI] –1.32 to –0.20; p < 0.01) than in controls. Peak untwisting velocity (PUV) was greater in high-static low-dynamic athletes (d = –0.43, 95% CI –0.84 to –0.03; p < 0.05) but less than controls in high-static high-dynamic athletes (d = 0.79, 95% CI 0.002–1.58; p = 0.05). Elite endurance athletes had significantly less twist and apical rotation than controls (d = 0.68, 95% CI 0.19–1.16, p < 0.01; d = 0.64, 95% CI 0.27–1.00, p = 0.001, respectively) but no differences in basal rotation. Meta-regressions showed LV mass index was positively associated with global longitudinal (b = 0.01, 95% CI 0.002–0.02; p < 0.05), whereas systolic blood pressure was negatively associated with PUV (b = –0.06, 95% CI –0.13 to –0.001; p = 0.05).ConclusionEchocardiographic 2D speckle tracking can identify subtle physiological differences in adaptations to cardiac strain and twist mechanics between athletes and healthy controls. Differences in speckle tracking echocardiography-derived parameters can be identified using suitable sporting categorizations.