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Treadmills (TM) and elliptical devices (EL) are popular forms of exercise equipment. The differences in the training stimulus presented by TM or EL are unknown. The purpose of this investigation was to evaluate oxygen consumption, energy expenditure, and heart rate on a TM or EL when persons exercise at the same perceived level of exertion. After measuring peak oxygen uptake (V[O.sub.2]peak) in 9 male and 9 female untrained college-aged participants, the subjects performed 2 separate 15-minute submaximal exercise tests on the TM and EL at a rating of perceived exertion (RPE) of 12-13. V[O.sub.2]peak was higher (p < 0.05) in the males (48.6 [+ or -] 1.5 vs. 45.2 [+ or -] 1.6 ml/kg/min) than the females (41.7 [+ or -] 1.8 vs. 38.8 [+ or -] 2.2 ml/kg/min) for both TM and EL (means [+ or -] standard error of the mean; for TM vs. EL respectively), but there were no differences in the measured V[O.sub.2]peak between TM or EL. During submaximal exercise there were no differences in RPE between TM and EL. Total oxygen consumption was higher (p < 0.05) in males (30.8 [+ or -] 2.2 vs. 34.9 [+ or -] 2.2 L) than females (24.1 [+ or -] 1.8 vs. 26.9 [+ or -] 1.7 L) but did not differ between TM and EL. Energy expenditure was not different between TM (569 [+ or -] 110 J) or EL (636 [+ or -] 120 kJ). Heart rate was higher (p < 0.05) on the EL (164 [+ or -] 16 beats/min) compared to the TM (145 [+ or -] 15 beats/ min). When subjects exercise at the same RPE on TM or EL, oxygen consumption and energy expenditure are similar in spite of a higher heart rate on the EL. These data indicate that during cross training or noncompetition-specific exercise, an elliptical device is an acceptable alternative to a treadmill. KEY WORDS rating of perceived exertion, oxygen consumption, heart rate, submaximal exercise, energy expenditure.

There is a need for objective biomarkers of dietary intake, because self-reporting is often subject to bias. We tested the validity of a biomarker for the fraction of dietary carbohydrate (CHO) from cane sugar and high fructose corn syrup ([C.sub.4] sugars) using natural [sup.13]C abundance of plasma glucose. In a randomized, single-blinded, crossover design, 5 participants consumed 3 weight-maintaining diets for 7 d, with a 2-wk washout between diet periods. Diets differed in the fraction of total CHO energy from [C.sub.4] sugars (5, 16, or 32%). During each diet period, blood samples were drawn at hours 0800 and 1600 on d 1, 3, and 5 and at 0800, 1000, 1200, 1400, and 1600 on d 7. The [delta][sup.13]C abundance of plasma glucose was analyzed via GC- isotope ratio MS. Within each diet period, [delta][sup.13]C abundance of the 0800 fasting glucose did not change from baseline with increasing time during a diet period; however, there was a strong positive correlation ([R.sup.2] = 0.89) between [delta][sup.13]C abundance of the glucose concentration at 1000 on d 7 and the percent of breakfast CHO from [C.sub.4] sugars. Also, [delta][sup.13]C abundance of the combined plasma glucose samples on d 7 demonstrated a strong positive correlation ([R.sup.2] = 0.90) with the percent of total daily CHO from [C.sub.4] sugars. The natural [delta][sup.13]C abundance of postprandial plasma glucose relative to dietary [C.sub.4] CHO content was a valid biomarker for contributions of [C.sub.4] caloric sweeteners from the previous meal. J. Nutr. 140: 333-337, 2010. doi: 10.3945/jn.109.114777.

Abstract Background We investigated the effects of a calcium-fortified beverage supplemented over 12 months on body composition in postmenopausal women (n = 37, age = 48–75 y). Methods Body composition (total-body percent fat, %FatTB; abdominal percent fat, %FatAB) was measured with dual energy x-ray absorptiometry. After baseline assessments, subjects were randomly assigned to a free-living control group (CTL) or the supplement group (1,125 mg Ca++/d, CAL). Dietary intake was assessed with 3-day diet records taken at baseline and 12 months (POST). Physical activity was measured using the Yale Physical Activity Survey. Results At 12 months, the dietary calcium to protein ratio in the CAL group (32.3 ± 15.6 mg/g) was greater than the CTL group (15.2 ± 7.5 mg/g). There were no differences from baseline to POST between groups for changes in body weight (CAL = 0.1 ± 3.0 kg; CTL = 0.0 ± 2.9 kg), %FatTB (CAL = 0.0 ± 2.4%; CTL = 0.5 ± 5.4%), %FatAB (CAL = -0.4 ± 8.7%; CTL = 0.6 ± 8.7%), or fat mass (CAL = 1.3 ± 2.6 kg; CTL = 1.3 ± 2.7 kg). Conclusion These results indicate that increasing the calcium to protein ratio over two-fold by consuming a calcium-fortified beverage for 12 months did not decrease body weight, body fat, or abdominal fat composition in postmenopausal women.

Purpose: To illustrate the effects of low-carbohydrate (LC) and grain-based (GB) diets on body composition, biomarkers, athletic training, and performance in an elite triathlete. Methods: The athlete followed 2 dietary interventions for 14 d while maintaining a prescheduled training program. Pre- and postintervention measurements for each diet included plasma and serum samples, resting energy expenditure, body composition, and a performance bike ride. Results: Compared with the GB diet, the LC diet elicited more disruptions to training and unfavorable subjective experiences. Total cholesterol, HDL cholesterol, LDL cholesterol, ratings of perceived exertion, and heart rate were elevated on the LC diet. Blood insulin, resting lactate, postexercise lactate, and C-reactive protein were lowest on the LC diet. Conclusion: The LC diet resulted in both favorable and unfavorable outcomes. The primary observation was a disruption to scheduled training on the LC diet. Researchers should consider how the potential mediating effect of disruptions to training could influence pretest--posttest designs. [ABSTRACT FROM AUTHOR]

Cooking foods affords numerous food safety benefits. During heating, Maillard reaction products ( MRPs) are formed. MRPs contribute sensory aspects to food, including color, taste, and texture. One MRP, acrylamide, has been implicated in negative health outcomes; however, emerging data suggests MRPs may also deliver certain health benefits. The food industry has taken steps to decrease acrylamide formation, but the perception that high levels of acrylamide compromise the nutritional benefit of certain foods has continued. Potatoes are susceptible to MRP formation during cooking but also are considered an affordable, high nutrient content food. In particular, potatoes contribute significantly to fiber and potassium intakes in the U.S. population, two nutrients of need. How, then, should potatoes be judged for effects on health? A structured evidence assessment was conducted to identify literature, specifically clinical trials, on MRPs from potatoes and health, as well as nutritional contribution of potatoes. The results indicate limited human clinical data are available on negative health outcomes of potato-based MRPs, whereas potatoes are important contributors of key nutrients, such as fiber and potassium. Therefore, a balanced benefit-risk approach is warranted in order to assure that decreasing consumption of certain foods, like potatoes, does not lead to unintended consequences of nutrition inadequacies. [ABSTRACT FROM AUTHOR]

There is a need for objective biomarkers of dietary intake, because self-reporting is often subject to bias. We tested the validity of a biomarker for the fraction of dietary carbohydrate (CHO) from cane sugar and high fructose corn syrup (C4 sugars) using natural 13C abundance of plasma glucose. In a randomized, single-blinded, crossover design, 5 participants consumed 3 weight-maintaining diets for 7 d, with a 2-wk washout between diet periods. Diets differed in the fraction of total CHO energy from C4 sugars (5, 16, 0132%). During each diet period, blood samples were drawn at hours 0800 and 1600 on d 1, 3, and 5 and at 0800, 1000, 1200, 1400, and 1600 on d 7. The δ13C abundance of plasma glucose was analyzed via GC-isotope ratio MS. Within each diet period, δ13C abundance of the 0800 fasting glucose did not change from baseline with increasing time during a diet period; however, there was a strong positive correlation (R² = 0.89) between δ13C abundance of the glucose concentration at 1000 on d 7 and the percent of breakfast CHO from C4 sugars. Also, δ13C abundance of the combined plasma glucose samples on d 7 demonstrated a strong positive correlation (R² = 0.90) with the percent of total daily CHO from C4 sugars. The natural δ13C abundance of postprandial plasma glucose relative to dietary C4 CHO content was a valid biomarker for contributions of C4 caloric sweeteners from the previous meal. [ABSTRACT FROM AUTHOR]