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

This study investigated skeletal muscle tissue oxygenation (StO2) desaturation in males and females across the adult lifespan. One-hundred-two individuals (51 females) of 41 young, 34 midlife, and 27 older adults completed a vascular occlusion test with near-infrared spectroscopy (NIRS+VOT). This included five minutes of arterial occlusion, inducing transient ischemia in the forearm flexor muscle group while recording StO2. The magnitude of desaturation (StO2mag) was quantified as the difference between baseline StO2 and the minimum StO2 value observed during ischemia. The rate of desaturation was also examined. Forearm adipose tissue thickness (ATT), forearm lean mass, and handgrip muscular strength were measured. A p ≤ 0.05 was considered significant. Two-way between factor ANOVAs indicated that males exhibited significantly (p<0.001) less ATT than females (collapsed across age) and that forearm lean mass (p<0.001) and muscular strength (p<0.001) decreased across the lifespan independent of sex. Bivariate analyses revealed significant (p<0.05) associations for sex, age, ATT, forearm lean mass, and muscular strength with the desaturation metrics. The ATT values demonstrated the strongest relations with StO2mag and desaturation rate (r = -0.620 and 0.618). Using a model comparison approach, ATT plus age offered the best predictive power for StO2mag and desaturation rate (R2 = 0.456 and 0.438) such that the inclusion of sex did not improve the models. These findings suggested differences in desaturation were primarily explained by variations in ATT and, to a lesser extent, age, but biological sex had no meaningful effect. Future studies must determine what other factors influence desaturation during ischemia.

Associations between daily time spent in physical activity (PA), sedentary behaviour (SB) and sleep (collectively referred to as 'movement behaviour') and quality of life (QOL) are typically studied without considering they are compositional, co-dependant variables. Study objectives were to use compositional data analysis to: 1) examine the relationship between movement behaviour composition and QOL, 2) estimate the degree to which changing time spent in any movement behaviour within the movement behaviour composition is associated with QOL. 7,918 older Canadian adults ≥ 65 years of age from the Canadian Longitudinal Study on Aging were studied using a quasi-longitudinal study design. Daily time spent in PA and SB were derived from self-reported Physical Activity Scale for the Elderly responses. Nighttime sleep was self-reported separately. QOL was assessed through the Satisfaction with Life Scale. Movement behaviour composition was significantly associated with QOL. Relative time spent in SB was negatively associated with QOL [HR = 0.89 (95% CI: 0.86, 0.93)]. Relative time spent in sleep was positively associated with QOL [HR = 1.10 (95% CI: 1.05, 1.16)]. Time displacement estimates revealed that greatest change in QOL occurred when time spent in PA was decreased and replaced with SB [HR = 0.96 (95% CI: 0.92, 0.99) for 45 min/day displacement]. Using compositional data analysis is advantageous because it shows how reduction in SB and increase in PA and sleep can lead to improvements in QOL for older Canadian adults.

This study investigated the impact of menstrual cycle (MC) phases and resistance training (RT) on muscle cross-sectional area (CSA) in two MCs utilizing a within-subject design. Twenty women with regular MCs had their legs randomly allocated to either the control (CON) or RT condition, which included 16 training sessions over two MCs. CSA, estradiol (E2), and progesterone (P4) were assessed during the menstruation (M), ovulation (O), and luteal (L) phases in the first (M1, O1, L1) and second (M2, O2, L2) MCs and at the beginning of the third MC (M3). P4 values were significantly higher during the luteal phase than during menstruation (P < 0.0001) and ovulation (P < 0.0001). No significant differences in E2 concentrations were observed between the MC phases (P = 0.08). For the RT condition, the CSA showed significant increases at O2, L2, and M3 compared to baseline (M1) (all P < 0.0001). No significant changes were observed for the CON condition during the two MCs (P > 0.05). However, RT condition showed a significant change in average CSA across two MCs. Additionally, individual analyses revealed that 19 participants showed variation in CSA above or below the minimum detectable difference during the two MCs. These findings suggest that changes in muscle CSA observed during two MCs may not be exclusively attributed to RT.

Fatigability varies depending on sex and contraction intensity during sustained exercise. This study examined the responses of time to task failure (TTF), performance fatigability (PF), and muscle oxygenation (SmO2) in males and females during isometric handgrip holds to failure (HTF) at 30% and 60% maximum voluntary isometric contraction (MVIC). Males (n=12) and females (n=12) performed a pre-MVIC, handgrip HTF at randomly ordered percentages of MVIC (either 30% or 60%), followed by a post-MVIC on the dominant arm. During the HTF testing, the TTF and SmO2 responses were recorded, and PF was determined from the pre- to post-MVICs. TTF for 30% MVIC HTF was greater than 60% MVIC HTF (p<0.001), but was not different between males and females (p=0.117). PF exhibited an inverse relationship with intensity for each sex, while males demonstrated greater PF than females for both 30% and 60% MVIC HTF. For the 60% MVIC HTF, males demonstrated greater desaturation than females (CI95% = [-28.1, -2.6%], p=0.021 d=0.621), but not for the 30% MVIC HTF (CI95% = [-12.2, 7.9%], p=0.315, d=0.621). Sex differences in PF and SmO2 may be attributed to the differences in muscle mass, absolute strength, contractile properties, and muscle metabolism between males and females. However, these proposed differences between males and females may not fully inform exercise performance (e.g., TTF). Sex-specific fatigue responses may be affected by complex physio-psychological mechanisms, and therefore, additional investigations under diverse exercise conditions are required to better prescribe exercise for both males and females.

This study aimed to understand contexts for buying food online with food delivery apps, meal kits, and online grocers in Canada. A total of 34 participants (24% identified as men) between the ages of 16 and 60 were interviewed over the phone. The participants were recruited through personal and professional networks, electronic word of mouth, and paid social media ads. The interviews were transcribed verbatim and thematic analysis was used to generate major themes: convenience, food literacy, and cost-effectiveness. Convenience was multifaceted, including protecting time, minimizing food preparation effort, and facilitating food access (without a vehicle, during illness and isolation, during bad weather, with mobility challenges, or while consuming drugs or alcohol). It was found that regardless of age, gender, or lifestyle, the contexts for using digital food retail services were similar. These services made food acquisition and preparation easier; however, the benefits may be at the detriment to food literacy. The added value that digital food retail services provided made up for any additional costs. This study highlighted the need for public health practitioners to consider different facets of convenience and the added value that digital food retail services offer when making healthy food shopping and preparation recommendations. Additionally, further investigation into the impacts of digital food retail on food literacy is warranted. Results from this study will be integrated into a larger survey exploring the relationship between online food purchasing behaviors and diet quality among Canadians.

Cognitive function is improved acutely after aerobic and/or resistance exercise, but it is unclear if the types of muscle contraction can influence this effect. This study tested the hypothesis that undertaking an acute bout of exercise with eccentric than concentric contractions would be more beneficial for improving cognitive function post-exercise in older adults. Twenty healthy older adults (66-75y) performed descending stair walking (DSW), ascending stair walking (ASW), and resistance exercise of the knee extensors with eccentric-only (RE-ECC) or concentric-only contractions (RE-CON) for 20 minutes each with a week between exercises in a randomized order. The Stroop tests of color naming (STCN) and conflicting color words (STCC), symbol digit modalities test, digit span test (DST), and two types of the trail making test (TMT-A, TMT-B) were assessed before and after sitting for 20 minutes (control session), and each exercise. A significant (p<0.05) improvement in the baseline test scores was found from the control session to the fourth exercise session. Time to complete the tests was significantly (p<0.05) reduced from pre- to post-exercise as well as after sitting for 20 minutes for STCN (-5.9±7.4s, Cohen's d=0.79), STCC (-8.9±11.1s, d=0.80), TMT-A (-22.6±9.7s, d=2.34) and TMT-B (-23.1±13.7s, d=1.69) without significant difference among the four exercise conditions. A significant (p<0.05) improvement of DST score was found from pre- to post-exercise for DSW (9.0±17.6%, d=0.51) and RE-ECC (6.5±10.6%, d=0.61), but not for ASW and RE-CON. These results partially supported the hypothesis that eccentric exercise could affect acute changes in cognitive function greater than concentric exercise.

We investigated whether pedal cadence (60 vs 100 rpm) affects oxygen uptake (V̇O2) and power output (PO) at two indexes of the heavy-to-severe-intensity domain boundary (i.e., critical power [CP] and respiratory compensation point [RCP]) and their correspondence. Fourteen adults (7 females, 23±2 yrs) cycled at 60 and 100 rpm during: i) a "Step-Ramp-Step" protocol to identify V̇O2 and PO at RCP; ii) 4-5 exhaustive constant-PO bouts for CP identification; and iii) a constant-power bout at CP to identify V̇O2 at CP. Separate two-way repeated measures ANOVA assessed whether V̇O2 and PO were affected by index (CP vs RCP) and cadence (60 vs 100 rpm). The V̇O2 was not affected by index (mean difference [MD]=73±197 mL·min-1; p=0.136) but there was an index x cadence interaction (p=0.014), such that V̇O2 was higher at 100 vs 60 rpm for CP (MD=142±169 mL·min-1; p=0.008) but not RCP (p=0526).. The PO was affected by cadence (MD=13±9 W; p<0.001) and index (MD=8±11 W; p=0.016), with no cadence x index interaction (p=0.168). The systematic bias in PO confirms cadence-specificity of CP and RCP. The relationship between these indexes and their change in unison in PO suggests a mechanistic link between these two heavy-to-severe domain boundary candidates.

Limited data exist regarding the impact of exercise intensity on irisin release and its association with insulin sensitivity in individuals of differing obesity status. The objective of this study was to investigate the impact of exercise intensity on the acute release of irisin in healthy weight individuals and individuals with obesity, and whether irisin release during acute exercise was associated with greater insulin sensitivity across obesity status. A randomized controlled crossover study was conducted on 26 non-obese (NOB) (BMI: 22.2±1.5 kg/m2) and 26 OB (BMI: 33.9±6.5 kg/m2) adults who performed an acute bout of moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), and rest. Irisin was quantified via ELISA and western blotting, and insulin sensitivity (Si) was estimated using the Matsuda index. OB displayed a significantly lower level of circulating irisin and protein expression compared to NOB (p<0.01). Insulin sensitivity was positively correlated with irisin release during MICT and HIIT in NOB (all p<0.05), but not in OB. Regarding irisin expression, NOB with high-Si had a 2.03-fold (p<0.05) increase during HIIT, while OB with high-Si had only a 1.54-fold increase (p<0.05). These results suggest that irisin is released differently according to obesity status and varying exercise intensities. OB individuals have a blunted irisin response to acute exercise and lower baseline irisin concentrations compared to NOB individuals. Although exercise stimulates irisin release in NOB individuals, only a greater exercise intensity stimulates irisin release in OB individuals. These findings are clinically relevant, as irisin is associated with greater insulin sensitivity.

Controlled Nutritional Status (CONUT) scores have been developed as quantitative tools that can be employed to gauge the nutritional status of individual patients. However, there has been very little research investigating the association between these CONUT scores and the function of the thyroid. As such, the present study was designed to address this research gap through the evaluation of a representative cohort of American adults. National Health and Nutrition Examination Survey (NHANES) data were herein used to separate subjects into those with normal nutritional status (CONUT score: 0-1) from those who were malnourished (CONUT scores > 1). Associations between these CONUT scores and the function of the thyroid were investigated through linear regression modeling, employing weighted analytical strategies and subgroup analyses. Overall, 8,082 individuals from the NHANES 2007-2012 cohort were enrolled in this analysis. These individuals exhibited a weighted mean CONUT score of 0.72 (0.02). 6661 (weighted proportion: 83.12%) in the normal nutritional status group and 1421 (16.88%) in the malnourished group. In adjusted analyses, subjects who were malnourished were found to present with an increase in FT4 levels (β = 0.033; p < 0.001 together with reduced TT3 levels (β = -3.526; p = 0.01). The present data offer evidence in support of higher CONUT scores, which correspond to malnutrition, being related to increases in FT4 levels together with reductions in TT3 levels. More studies will be crucial to further probe the mechanistic drivers of these results.

A mother's intrauterine environment influences her health and that of her offspring, at birth and in the future. Herein, we present an overview of our Canadian Institutes of Health Research (CIHR)-funded grant "Understanding the impact of maternal and infant nutrition on infant/child health"-set within The NutriGen Birth Cohort Alliance. NutriGen is a consortium of four Canadian prospective birth cohorts representing >5000 mother-child pairs of diverse ethnic groups including South Asians, White Europeans, and Indigenous peoples. We summarize our objectives and main findings on outcomes of maternal diet, gestational diabetes, birth weight, cardiometabolic health, the microbiome, and epigenetic modifications. We append this work with 10 key messages when conducting multiethnic research and review our knowledge translation products. We describe the clinical impact of our research on maternal and child health and conclude with future directions on biomarker discovery, expansion to other ethnic groups, and interventions for high-risk populations.