Accurate assessments of a target population’s energy intake (EI) are essential to prevent poor nutritional status. However, self-reported dietary records (DRs) or food frequency questionnaires (FFQs) are not always accurate, thereby requiring validation and calibration studies. This study aimed to validate the EI estimated by a FFQ using the doubly labeled water (DLW) method. Participants were 109 Japanese older adults (50 women and 59 men) aged 65–88 years. The EI was obtained by a DR and 47-item FFQ over 1 year. The total energy expenditure (TEE) was measured by DLW for ~2 weeks. EI was significantly lower than TEE (p < 0.01); ratios of EI assessed by DR and FFQ against TEE were 0.91 ± 0.17 and 0.82 ± 0.22, respectively. TEE was significantly and moderately correlated with the EI estimated by the DR (r = 0.45, p < 0.01) and FFQ (r = 0.37, p < 0.01). Furthermore, the EI correlation coefficients estimated by DR and the FFQ in this study were not significantly different (p = 0.46). The EI/TEE ratio was significantly and negatively correlated with the body mass index (BMI). In conclusion, EI estimated with a DR or FFQ modestly correlated with TEE, and calibrating EI with a developed equation in this study can attenuate the underestimation of EI.

High-intensity exercise in athletes results in mainly the production of excess reactive oxygen species (ROS) in skeletal muscle, and thus athletes should maintain greater ROS scavenging activity in the body. We investigated the changes in six different ROS-scavenging activities in athletes following high-intensity anaerobic exercise. A 30-s Wingate exercise test as a form of high-intensity anaerobic exercise was completed by 10 male university track and field team members. Blood samples were collected before and after the exercise, and the ROS-scavenging activities (OH•, O₂•⁻, ¹O₂, RO• and ROO•, and CH₃•) were evaluated by the electron spin resonance (ESR) spin-trapping method. The anaerobic exercise significantly increased RO• and ROO• scavenging activities, and the total area of the radar chart in the ROS-scavenging activities increased 178% from that in pre-exercise. A significant correlation between the mean power of the anaerobic exercise and the ¹O₂ scavenging activity was revealed (r = 0.72, p < 0.05). The increase ratio in OH• scavenging activity after high-intensity exercise was significantly greater in the higher mean-power group compared to the lower mean-power group (n = 5, each). These results suggest that (i) the scavenging activities of some ROS are increased immediately after high-intensity anaerobic exercise, and (ii) an individual’s OH• scavenging activity responsiveness may be related to his anaerobic exercise performance. In addition, greater pre-exercise ¹O₂ scavenging activity might lead to the generation of higher mean power in high-intensity anaerobic exercise.

Body composition changes with age, with fat mass (FM) increasing and fat-free mass (FFM) decreasing. Higher physical activity and high or adequate protein intake are thought to be beneficial in preventing the loss of skeletal muscle mass in the elderly. We aimed to investigate the relationships between physical activity, protein intake, and FFM in older people with mild disability. Total energy expenditure (TEE) under free-living conditions was assessed using the doubly-labelled water (DLW) method, and physical activity was measured using a triaxial accelerometer. Dietary intake was assessed using a self-recorded food intake diary during the DLW period. Percent FFM was significantly positively correlated with protein intake and physical activity level (PAL) after adjustment for age and sex (protein intake r = 0.652, p < 0.001, PAL r = 0.345, p = 0.011). In multiple linear regression analysis, when PAL, moderate-to-vigorous physical activity (MVPA), or protein intake were included, 31%, 32%, and 55%, respectively, of the variation in %FFM was explained. Moreover, the addition of both PAL/MVPA and protein intake explained 61%/60%, respectively, of the variation in %FFM. Either protein intake above the currently recommended level or higher levels of physical activity would be beneficial for the maintenance of high %FFM.

We investigated effects of molecular hydrogen (H₂) supplementation on acid-base status, pulmonary gas exchange responses, and local muscle oxygenation during incremental exercise. Eighteen healthy, trained subjects in a randomized, double-blind, crossover design received H₂-rich calcium powder (HCP) (1500 mg/day, containing 2.544 µg/day of H₂) or H₂-depleted placebo (1500 mg/day) for three consecutive days. They performed cycling incremental exercise starting at 20-watt work rate, increasing by 20 watts/2 min until exhaustion. Breath-by-breath pulmonary ventilation ($\dot{\mathrm{V}}$_E) and CO₂ output ($\dot{\mathrm{V}}$CO₂) were measured and muscle deoxygenation (deoxy[Hb + Mb]) was determined via time-resolved near-infrared spectroscopy in the vastus lateralis (VL) and rectus femoris (RF). Blood gases’ pH, lactate, and bicarbonate (HCO₃⁻) concentrations were measured at rest and 120-, 200-, and 240-watt work rates. At rest, the HCP group had significantly lower $\dot{\mathrm{V}}$_E, $\dot{\mathrm{V}}$CO₂, and higher HCO₃⁻, partial pressures of CO₂ (PCO₂) versus placebo. During exercise, a significant pH decrease and greater HCO₃⁻ continued until 240-watt workload in HCP. The $\dot{\mathrm{V}}$_E was significantly lower in HCP versus placebo, but HCP did not affect the gas exchange status of $\dot{\mathrm{V}}$CO₂ or oxygen uptake ($\dot{\mathrm{V}}$O₂). HCP increased absolute values of deoxy[Hb + Mb] at the RF but not VL. Thus, HCP-induced hypoventilation would lead to lower pH and secondarily impaired balance between O₂ delivery and utilization in the local RF during exercise, suggesting that HCP supplementation, which increases the at-rest antioxidant potential, affects the lower ventilation and pH status during incremental exercise. HPC induced a significantly lower O₂ delivery/utilization ratio in the RF but not the VL, which may be because these regions possess inherently different vascular/metabolic control properties, perhaps related to fiber-type composition.

Obesity and overweight are increasing in prevalence in developed countries as a result of changing dietary habits and a lack of physical activity. The purpose of the present study was to evaluate the changes in body composition during short-term overfeeding using the three-component model, which is composed of fat mass (FM), total body water (TBW), and fat-free dry solids (FFDS).

Objective: Self-reported energy intake (EI) estimation may incur systematic errors that could be attenuated through biomarker calibration. We aimed to confirm whether calibrated EI was comparable to total energy expenditure (TEE) measured using the doubly labelled water (DLW) technique. Design: Cross-sectional study. Setting: General older population from the Kyoto–Kameoka Study, Japan. Participants: This study included sub- and main cohorts of 72 and 8,058 participants aged ≥65 years, respectively. EI was evaluated using a validated FFQ, and calibrated EI was obtained using a previously developed equation based on the DLW method. TEE was considered representative of true EI and also measured using the DLW method. We used a Wilcoxon signed-rank test and correlation analysis to compare the uncalibrated and calibrated EI with TEE. Results: In the sub-cohort, the median TEE, uncalibrated EI, and calibrated EI were 8,559 kJ, 7,088 kJ, and 9,269 kJ, respectively. The uncalibrated EI was significantly lower than the TEE (median difference = −1,847 kJ; interquartile range [IQR]: −2,785 to −1,096), although the calibrated EI was not (median difference = 463 kJ; IQR: −330 to 1,541). The uncalibrated (r = 0.275) and calibrated EI (r = 0.517) significantly correlated with TEE. The reproducibility was higher for calibrated EI (interclass correlation coefficient [ICC] = 0.982) than for uncalibrated EI (ICC = 0.637). Similar findings were observed when stratifying the sample by sex. For medians, uncalibrated EI was lower (˜17%) than calibrated EI in the main cohort. Conclusions: Biomarker calibration may improve the accuracy of self-reported dietary intake estimation.