Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme最新文献

This paper provides an overview of topics discussed by clinicians and researchers invited to speak at the Canadian Nutrition Society's Thematic Conference 2023, which was centered on advances in research and practice in the assessment and treatment of disordered eating and eating disorders. Presenters emphasized the importance of understanding how systemic factors such as racism, weight stigma, and COVID-19 affect the assessment and treatment of eating disorders, and proposed strategies for addressing these inequities. In this paper, we provide actionable recommendations for clinicians working with individuals with eating disorders; professional development, cultural competence, and equitable assessment and treatment practices are discussed.

This study investigated the impact of a multiday heatwave on nocturnal physiology, behavior, and sleep under controlled conditions with comprehensive monitoring of environmental factors and participant activities. Seven young healthy males were confined for 10 days in controlled conditions that ranged between hot-to-warm (day: 35.4 °C, night: 26.3 °C) during nights 4-6 and temperate (day: 25.4 °C, night: 22.3 °C) before (nights 1-3) and after (nights 7-10) the heatwave. Measurements included core and skin temperatures, heart rate, sympathovagal balance, vasomotion indicators, urine samples, blanket coverage, subjective sleep assessments, and partial polysomnography. The average nocturnal core temperature was 0.2 °C higher during and after the heatwave compared to the pre-heatwave period, with this difference being more pronounced (+0.3 °C) in the first 2 h of sleep (p < 0.001). For every 0.1 °C rise in overnight core temperature, the total sleep time decreased by 14 min (pseudo-R² = 0.26, p = 0.01). The elevated core temperatures occurred despite the participants exhibiting evident thermoregulatory behavior, as they covered 30% less body surface during the heatwave compared to pre- and post-heatwave periods (p < 0.001). During the heatwave, mean skin temperature at bedtime was 1.3 °C higher than pre-heatwave and 0.8 °C higher than post-heatwave periods (p < 0.001). No differences in other responses, including heart rate and vasomotion indicators, were observed. The paper details a 20-min sleepwalking episode that was coupled with marked changes in sleepwalker's thermophysiological responses. In conclusion, the simulated heatwave resulted in higher overnight core temperature which was associated with reduced total sleep time. Behavioral thermoregulation during sleep may serve as a defense against these effects, though more research is needed.

Changes in hydration status occur throughout the day affecting physiological and behavioural functions. However, little is known about the hydration status of free-living Japanese children and the seasonality of this response. We evaluated hydration status estimated by urine osmolality (Uosm) in 349 children (189 boys and 160 girls, 9.5 ± 2.6 years, range: 6-15 years) upon waking at home and during a single school day in spring (April) and summer (July). Further, we assessed the efficacy of employing self-assessment of urine colour (UC; based on an 8-point scale) by children to monitor their hydration status. Early morning Uosm was greater in the spring (903 ± 220 mOsm L^-1; n = 326) as compared to summer (800 ± 244 mOsm L^-1; n = 125) (P = 0.003, paired t test, n = 104). No differences, however, were observed in Uosm during the school day (P = 0.417, paired t test, n = 32). While 66% and 50% of children were considered underhydrated (Uosm ≥ 800 mOsm L^-1) upon waking in the spring and summer periods, respectively, more children were underhydrated (∼12%) during the school day. Self-reported UC was similar between seasons as assessed in the morning and school day (P ≥ 0.101, paired t test), which differed from the pattern of responses observed with Uosm. We showed that a significant number of Japanese children are likely underhydrated especially in the spring period. Children do not detect seasonal changes in hydration from self-assessed UC, limiting its utility to manage hydration status in children.

We investigated the influence of anaerobic speed reserve (ASR) on post-activation performance enhancement (PAPE). Twenty-two endurance runners and triathletes were evaluated for maximum sprinting speed (MSS) and countermovement jump (CMJ) before (non-fatigued) and after (fatigued) an incremental running test. They were allocated in LASR (low-ASR) and HASR (high-ASR) groups for comparisons between conditions. HASR showed greater CMJ and MSS (both p ≤ 0.005) performances, with enhanced CMJ in fatigued condition (p ≤ 0.008). Significant correlations were found between ASR, CMJ, and MSS in both conditions (p ≤ 0.01) for the entire sample, and between ∆CMJ and ∆MSS (p ≤ 0.001) in LASR. Our results show that ASR profile influences PAPE.

Reference equations for fat-free mass (FFM) and lean soft tissue mass (LM) measures obtained from dual-energy X-ray absorptiometry (DEXA) are important for the interpretation of body composition. This study developed and validated reference equations for FFM and LM using DEXA from the Canadian Longitudinal Study on Aging. Reference equations were developed using data from a random population-based sample of ostensibly healthy and functionally independent adults aged 45-85 years. Reference equations for absolute (accounting for age, sex, height, and body mass) and height-adjusted aka index (accounting for age, sex, and body mass index) measures of FFM and LM were developed using quantile regression. Reference equations were respectively developed and validated in derivation (80%) and validation cohorts (20%). Reference equations were applied to symptomatic adults with self-reported chronic obstructive pulmonary disease (COPD) or heart disease to assess discriminant validity; and compared with other published equations to assess performance. Bland-Altman analyses and Lin's concordance correlation coefficients were utilised to assess agreement. Reference equations for 5th, 10th, 50th, 90th, and 95th percentiles were developed for DEXA-derived estimates of FFM and LM based on 1881 healthy participants (57% male) aged 55 [IQR: 50-61] years. Reference equations performed comparably in the validation cohort and discriminated reference values between ostensibly healthy adults and people with symptomatic COPD or heart disease. Previously published reference equations tended to over- or under-predict estimates of LM compared with the current reference equations. This study provides a comprehensive and validated set of reference equations for estimating and interpreting FFM and LM from DEXA in Canadian adults aged 45-85 years, although additional validation may be required for those >75 years.

The effects of exogenous ketones on appetite and food intake remain elusive, especially for people with type 2 diabetes (T2D). This study aimed to determine whether acute ingestion of an oral ketone monoester supplement (KME) affected appetite sensations, prospective food consumption and intake in T2D. Results showed that acute KME ingestion did not significantly alter appetite scores. However, there was a tendency for lower energy intake during an ad libitum meal 3 h following ketone ingestion compared to non-energetic placebo. Further research is warranted to understand the long-term effects of exogenous ketones for energy and macronutrient intake in T2D.

The purpose of this study was to quantify the total energy expenditure (TEE) of international female rugby union players. Fifteen players were assessed over 14 days throughout an international multi-game tournament, which represented two consecutive one-match microcycles. Resting metabolic rate (RMR) and TEE were assessed by indirect calorimetry and doubly labelled water, respectively. Physical activity level (PAL) was estimated (TEE:RMR). Mean RMR, TEE, and PAL were 6.60 ± 0.93 MJ·day^-1 (1578 ± 223 kcal·day^-1), 13.51 ± 2.28 MJ·day^-1 (3229 ± 545 kcal·day^-1), and 2.0 ± 0.3 AU, respectively. There was no difference in TEE (13.74 ± 2.31 (3284 ± 554 kcal·day^-1) vs. 13.92 ± 2.10 MJ·day^-1 (3327 ± 502 kcal·day^-1); p = 0.754), or PAL (2.06 ± 0.26 AU vs. 2.09 ± 0.23 AU; p = 0.735) across microcycles, despite substantial decreases in training load (total distance: -8088 m, collisions: -20 n, training duration: -252 min). After correcting for body composition, there was no difference in TEE (13.80 ± 1.74 (3298 ± 416 adj. kcal·day^-1) vs. 13.16 ± 1.97 (3145 ± 471 adj. kcal·day^-1) adj. MJ·day^-1, p = 0.190), RMR (6.49 ± 0.81 (1551 ± 194 adj. kcal·day^-1) vs. 6.73 ± 0.83 (1609 ± 198 adj. kcal·day^-1) adj. MJ·day^-1, p = 0.633) or PAL (2.15 ± 0.14 vs. 1.87 ± 0.26 AU, p = 0.090) between forwards and backs. For an injured participant (n = 1), TEE reduced by 1.7 MJ·day^-1 (-401 kcal·day^-1) from pre-injury. For participants with illness (n = 3), TEE was similar to pre-illness (+0.49 MJ·day^-1 (+117 kcal·day^-1)). The energy requirements of international female rugby players were consistent across one-match microcycles. Forwards and backs had similar adjusted energy requirements. These findings are critical to inform the dietary guidance provided to female rugby players.

Mitochondrial dysfunction is implicated in heat-induced skeletal muscle (SKM) injury and its underlying mechanisms remain unclear. Evidence suggests that cellular ions and molecules, including divalent cations and adenine nucleotides, are involved in the regulation of mitochondrial function. In this study, we examined Ca²⁺, Mg²⁺, and NAD⁺ levels in mouse C2C12 myoblasts and SKM in response to heat exposure. During heat exposure, mitochondrial Ca²⁺ levels increased significantly, whereas cytosolic Ca²⁺ levels remained unaltered. The mitochondrial Ca²⁺ levels in the SKM of heat-exposed mice were 28% higher compared to control mice. No changes in cytosolic Ca²⁺ were detected between the two groups. Following heat exposure, cytosolic and mitochondrial Mg²⁺ levels were reduced by 47% and 23% in C2C12 myoblasts, and by 51% and 44% in mouse SKMs, respectively. In addition, heat exposure decreased mitochondrial NAD⁺ levels by 32% and 26% in C2C12 myoblasts and mouse SKMs, respectively. Treatment with the NAD⁺ precursor nicotinamide riboside (NR) partially prevented heat-induced depletion of NAD⁺. Additionally, NR significantly reduced heat-increased mitochondrial fission, mitochondrial depolarization, and apoptosis in C2C12 myoblasts and mouse SKMs. No effects of NR on heat-induced changes in intracellular Ca²⁺ and Mg²⁺ levels were observed. This study provides in vitro and in vivo evidence that acute heat stress causes alterations in mitochondrial Ca²⁺, Mg²⁺, and NAD⁺ homeostasis. Our results suggest mitochondrial NAD⁺ homeostasis as a therapeutic target for the prevention of heat-induced SKM injury.

Eating in the absence of hunger (EAH) has been associated with overweight and obesity during childhood. The gold standard to assess this behavior is a laboratory-based protocol, but a questionnaire to assess EAH more efficiently in children and adolescents has been developed and validated in English. We assessed construct validity (structural and convergent validity) and reliability (internal consistency and temporal stability) of a French translation of the EAH Questionnaire for Children and Adolescents among French-Canadian youths. We recruited participants in Montreal (Canada) aged 7-15 years old, who completed the questionnaire and provided anthropometric data. We asked participants to complete the questionnaire a second time ∼4 weeks later. The questionnaire consists of 14 questions and 3 subscales that assess EAH due to negative affect, fatigue/boredom, and external cues. We performed an exploratory factor analysis to test the factor structure and we calculated Cronbach alpha coefficients and intra-class correlations to assess internal consistency and temporal stability, respectively. We assessed associations between EAH and BMI z-score using Pearson correlations. We included 196 participants (50% girls; mean (SD) 11.9 (2.3) years old) for the first completion and 153 for the second completion. The exploratory factor analysis generated the same three subscales as the original questionnaire: negative affect (α = 0.86; ICC = 0.78), fatigue/boredom (α = 0.75; ICC = 0.70), and external cues (α = 0.68; ICC = 0.54). Participant's BMI z-scores were positively associated with the average scores from the negative affect subscale (r = 0.19; ρ = 0.009). Our results suggest that this questionnaire has an adequate construct validity, internal consistency, and temporal stability.

Canada's food guide (CFG) 2019 provides dietary guidance for all Canadians; however, there is no tool available to help Canadians easily determine how individual foods align with CFG. Therefore, the objectives of this study were (1) to develop a nutrient profile model, Canadian Food Scoring System (CFSS), to rank the healthfulness of individual foods according to the recommendations of CFG; and (2) to assess its validity. The CFSS was developed based on CFG, leveraging existing Canadian labelling regulations to set quantitative criteria for the CFG recommendations. The CFSS included three main steps: (1) classifying foods into the nutritious food categories and assigning points based on the alignment with the recommendations of CFG; (2) deducting points based on the levels of saturated fat, sugars, and sodium using thresholds from Canadian front-of-pack labelling regulations; and (3) calculating the final score from the first two steps to classify foods into one of five categories: "very poor," "poor," "fair," "good," or "excellent" choice. Convergent validity was assessed by examining the alignment of the CFSS with Health Canada's CFG-Food Classification System using a national food composition database and the Healthy Eating Food Index-2019 using nationally representative dietary intake survey data. The CFSS showed strong correlation with the CFG-Food Classification System (ρ = 0.782, p < 0.001) and moderate correlation with the Healthy Eating Food Index-2019 (r = 0.636, p < 0.001), indicating good convergent validity both at the food and dietary level. The newly developed CFSS can assess the alignment of individual foods with CFG, which can be used to help Canadians more easily make healthy food choices.