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

Identifying biomarkers can help in the early detection of muscle loss and drive the development of new therapies. Research suggests a potential link between retinol-binding protein 4 (RBP4) and muscle mass, particularly in postmenopausal women. This study aimed to examine the association between baseline RBP4 levels and changes in appendicular lean mass (ALM), an indicator of muscle mass, in postmenopausal women. A 12-month follow-up period (n = 153) included baseline and 12-month ALM assessments using DXA. ALM was normalized to squared height (ALMI). Baseline evaluations encompassed insulin resistance via HOMA-IR and immunoassay magnetic bead panel measurements of RPB4, IL-6, TNF-α, and IL-10. Postmenopausal women were categorized into higher (n = 77) and lower (n = 76) RPB4 groups based on baseline RPB4 values. Their changes in ALMI were compared using Mann-Whitney tests. General linear model was employed to evaluate the predictive power of baseline RBP4 for ALMI changes, adjusting for confounding variables: age, physical activity, smoking status, body fat, HOMA-IR, inflammatory markers (TNF-α and IL-6), and anti-inflammatory factor (IL-10). The higher RBP4 group exhibited a more pronounced reduction in ALMI compared to the lower RBP4 group (Higher RBP4 = -0.39 kg/m², 95% CI: -0.48 to -0.31 kg/m²vs. Lower RBP4 = -0.24 kg/m², 95% CI: -0.32 to -0.15 kg/m², P = 0.011). After adjusting for confounding factors, the association between baseline RBP4 changes and ALMI remained (b = -0.008, SE = 0.002, P < 0.001), indicating higher baseline RBP4 values linked to greater ALMI reduction. Our findings support RBP4 as a potential biomarker for changes in muscle mass in postmenopausal women.

Understanding the dietary patterns of First Nations is crucial for addressing health disparities and promoting well-being. Historical assaults (colonization and loss of control over their lands) have strongly altered dietary practices and impacted health outcomes for generations. Canada conducts regular surveys to assess the extent to which individuals adhere to dietary guidelines. However, Indigenous peoples living on reserves are excluded from these surveys. This study aims to assess the diet quality of First Nations adults using the Healthy Eating Food Index-2019 (HEFI-2019) and the Canadian Healthy Eating Index 2007 (C-HEI 2007) and identify their influencing factors. Data were collected from adults (19 years and older) across ninety-two First Nations communities throughout Canada. Participants provided information on sociodemographic factors and dietary intake using structured questionnaires and 24h dietary recalls. Statistical analyses included mean scores and regression models to assess associations between dietary indices and influencing factors. The mean HEFI-2019 and C-HEI 2007 scores among First Nations adults were 35/80 and 49/100, respectively, indicating suboptimal adherence to dietary guidelines compared to the Canadian population. Factors such as region, age, sex, education level, number of working people in the household, smoking status, and traditional food intake significantly influenced diet quality. This study underscores the importance of understanding and improving the diet quality of First Nations adults as measured by HEFI-2019 and C-HEI 2007 scores. While acknowledging the low adherence to dietary guidelines, particularly in younger age groups, the study highlights the positive influence of traditional foods on diet quality within Indigenous communities.

Heat exposure's effect on glucose tolerance depending on the amount of body exposure, likely relating to autonomic nervous system balance. We assessed how partial-body heat exposure at two different levels of the lower extremities would affect glucose tolerance and autonomic nervous system balance measured via heart rate variability. We hypothesized feet-heating would improve glucose tolerance without affecting heart rate variability while calf-heating would worsen glucose tolerance and decrease heart rate variability compared to a thermoneutral control condition. In a randomized, controlled, crossover trial, healthy participants' (N=31, 23(3)years, 45% male) glucose tolerance was measured in A)thermoneutral; B)feet-heating; and C)calf-heating conditions. Every 30 minutes for 2 hours, blood glucose, heart rate, heart rate variability, tympanic temperature, thermal comfort scores, and blood pressure were measured. There were significant interactions between condition and time for blood glucose (F(4.6,72.6)=2.6,p=.036), heart rate (F(3.4,54.5)=3.5,p=.017), heart rate variability (F(4.3,63.2)=7.5,p<.0001), tympanic temperature (F(8,268)=2.4,p=.014), and thermal comfort scores (F(8,248)=22.1,p<.0001). Calf-heating increased 90-minute glucose (+12(95%CI: 3 to 21)mg/dL,p=.013) and decreased heart rate variability throughout (mean decrease: 13-22%,p<.007), while feet-heating lowered 90-minute glucose (-7(95%CI:-16 to +1)mg/dL,p=.090) without affecting heart rate variability (p=.14-.99). Blood pressure and body temperature were similar between conditions, but heart rate and thermal comfort scores increased with heating. Calf-heating worsens, while feet-heating may improve, glucose tolerance. Changes in heart rate variability coincide with changes in glucose tolerance despite unchanged body temperature. Whether heart rate variability can be used to monitor autonomic nervous system balance during heating to the effect on acute glycemic indices should be further explored.

Explosive movements requiring high force and power outputs are integral to many sports, posing distinct challenges for the neuromuscular system. Traditional resistance training can improve muscle strength, power, endurance, and range of motion; however, evidence regarding its effects on athletic performance, such as sprint speed, agility, and jump height, remains conflicting. The specificity of resistance training movements, including velocity, contraction type, and joint angles affects performance outcomes, demonstrates advantages when matching training modalities with targeted sports activities. However, independent of movement speed, the intent to contract explosively (ballistic) has also demonstrated high velocity-specific training adaptations. The purpose of this narrative review was to assess the impact of explosive or ballistic contraction intent on velocity-specific training adaptations. Such movement intent may predominantly elicit motor efferent neural adaptations, including motor unit recruitment and rate coding enhancements. Plyometrics, which utilize rapid stretch-shortening cycle (SSC) movements may augment high-speed movement efficiency and muscle activation, possibly leading to improved motor control through adaptations like faster eccentric force absorption, reduced amortization periods, and quicker transitions to explosive concentric contractions. An optimal training paradigm for power and performance enhancement might involve a combination of maximal explosive intent training with heavier loads and plyometric exercises with lighter loads at high velocities. This narrative review synthesizes key literature to answer whether contraction intent or movement speed is more critical for athletic performance enhancement, ultimately advocating for an integrative approach to resistance training tailored for sports-specific explosive action.

Poor glucose regulation associated with gradual insulin resistance is a significant risk factor in several age-related chronic diseases. An eating plan that promotes a lower carbohydrate intake may have a beneficial effect on glucose metabolism. This study aimed to evaluate how a diet reduced carbohydrate by 32% (RCHO) over a 2-month period would influence the metabolic profile of older individuals (N = 24) living in a retirement home (RH). A continuous glucose monitor was used to measure blood glucose during four periods: the standard diet before (baseline) and after (washout) the intervention, during the 4 initial days of the RCHO diet (RCHO-early), and the final days of the 2-month intervention (RCHO-end). The blood metabolic profile was also measured (glucose, ketones, insulin, triglycerides and cholesterol). RCHO intake decreased average blood glucose compared to the standard diet in hyperglycemic participants: RCHO-early 7.8 ± 1.0 vs 7.5 ± 1.1 mM (p = 0.012) and RCHO-end 7.8 ± 1.0 vs 7.0 ± 0.9 mM (p = 0.050). In the hyperglycemic participants, the percentage of time spent in hyperglycemia (> 10.0 mM) decreased by 50% during the RCHO-early (p = 0.012) and by 66% at RCHO-end (p = 0.021) compared to baseline. Glycated hemoglobin was significantly lower at RCHO-end in both hyperglycemic and normoglycemic participants compared to baseline (p < 0.008). Plasma ketones increased 3-fold in hyperglycemic participants at RCHO-end compared to baseline (p < 0.028). This study shows that an RCHO diet has metabolic health benefits in an older population and confirms its safety, tolerability, and acceptability in a RH. (NCT06022094).

High consumption of ultra-processed foods and drinks (UPF) has been linked to poor diet quality and an increased risk of non-communicable diseases. To inform public policies and interventions aimed at reducing UPF intake in Canada, updated information on UPF intake among different sociodemographic groups is needed. This study, using data from 5,872 adults aged 18 years and older from the International Food Policy Study (2018-2019), aims to estimate the dietary energy contribution of UPF and assess its variation among sociodemographic subgroups. All foods and drinks reported in a single 24-hour dietary recall were classified using the Nova system. We estimated the mean proportion of total daily energy from UPF and subcategories of UPF in the overall sample and among sociodemographic subgroups. Multivariable linear regression models evaluated the association between sociodemographic characteristics with the proportion of total daily energy from UPF. On average, adults consumed 45.2% of their total daily energy from UPF. UPF consumption was slightly higher among males than females (49.4% vs. 47.6%, p=0.039) and younger adults aged 19-30 years compared with older adults aged 51-64 years (50.0% vs. 47.2%, p=0.029), adjusting for a range of sociodemographic factors. Overall, UPF consumption was relatively high among adults in all sociodemographic subgroups, highlighting the need for policies to decrease UPF consumption in the entire population.

This randomized, placebo-controlled, double-blind, parallel trial investigated whether generally healthy adult, nonelite runners would have a greater time-to-exhaustion during submaximal treadmill running with probiotic versus placebo supplementation. It was hypothesized that the probiotic would impact training progression by reducing gastrointestinal (GI) and cold/flu symptoms. Participants who typically ran ≥24 km/week, ran or cross-trained 3-5 days per week, and had a maximal oxygen intake (V̇O₂ max) in the 60-85th percentile were enrolled. V̇O₂ max was used to establish individualized workload settings (85% of V̇O₂ max) for the submaximal endurance tests at baseline and following 6 weeks of supplementation with a probiotic (Lactobacillus helveticus Lafti L10, 5×10⁹ CFU/capsule/day) or placebo. Participants self-reported GI and cold/flu symptoms and physical activity via daily and weekly questionnaires. Outcomes were tested using a linear model to determine if mean response values adjusted for baseline differed between groups. Twenty-eight participants (n = 14/group), aged 25 ± 5 years (mean ± SD) with a body mass index of 23 ± 3 kg/m², completed the study. At the final visit the probiotic group had a lower time-to-exhaustion versus the placebo group (P = 0.01) due to an increase in time-to-exhaustion with the placebo (1344 ± 188 to 1565 ± 219 s, P = 0.01) with no change with the probiotic (1655 ± 230 to 1547 ± 215 s, P = 0.23). During the intervention, the probiotic group completed fewer aerobic training sessions per week (P = 0.02) and trained at a lower intensity (P = 0.007) versus the placebo group. Few GI and cold/flu symptoms were reported with no differences between groups. Time-to-exhaustion increased in the placebo group, possibly due to differences in training habits.

We recently explored the cardiopulmonary interactions during partial unloading of the respiratory muscles during exercise. Expanding upon this work, we present a noteworthy case study whereby we eliminated the influence of respiration on cardiac function in a conscious but mechanically ventilated human during exercise. This human was a young healthy endurance-trained male who was mechanically ventilated during semi-recumbent cycle exercise at 75 Watts (W) (∼30% W_max). During mechanically ventilated exercise, esophageal pressure was reduced to levels indistinguishable from the cardiac artefact which led to a 94% reduction in the power of breathing. The reduction in respiratory pressures and respiratory muscle work led to a decrease in cardiac output (-6%), which was due to a reduction in stroke volume (-13%), left ventricular end-diastolic volume (-15%), and left-ventricular end-systolic volume (-17%) that was not compensated for by heart rate. Our case highlights the influence of extreme mechanical ventilation on cardiac function while noting the possible presence of a maximal physiological limit to which respiration (and its associated pressures) impacts cardiac function when the power of breathing is maximally reduced.

Disordered eating refers to a range of eating behaviours and attitudes towards weight and food that can negatively influence physical and psychosocial well-being. The menopausal transition could be a vulnerable period for disordered eating due to major hormonal fluctuations, menopausal symptoms, common body composition shifts, and an increased risk of psychological challenges. This systematic review aimed to summarize evidence on the associations between the menopausal transition and disordered eating. Records published before October 2023 were identified through MEDLINE, PsycINFO, Scopus, Embase, and CINAHL. Studies investigating associations between menopausal status, menopausal symptoms, or reproductive hormone levels, and disordered eating during the menopausal transition were sought. A total of 1301 non-duplicate records were screened, with 10 studies deemed eligible for inclusion. Most included studies used a cross-sectional design (n = 9). Findings include potentially higher levels of binge eating during the perimenopausal stage, whereas restrictive eating behaviours appeared more common during postmenopause compared to premenopause. Both studies investigating menopausal symptoms found strong positive associations with disordered eating. Nonetheless, findings are equivocal with contrasting results and limited methodological quality across studies. Further research is needed to verify these findings and better assist health professionals in supporting healthy eating behaviours in menopausal women during this complex transition. (PROSPERO ID: CRD42021290736).

Snacking is nearly universal among children but there is growing concern around snacking patterns and energy contribution. This study aimed to characterize temporal snacking patterns among Canadian children and adolescents. A cross-sectional analysis drew on data from 5209 respondents aged 4-18 years from the 2015 Canadian Community Health Survey Nutrition, using one 24 h dietary recall. Descriptive statistics estimated proportions of morning, afternoon, and evening snackers, the mean caloric contribution of each snacking period to total daily energy intake, and the top food categories consumed as snacks (kcal per capita). Snacking was nearly universal and accounted for one of every four calories consumed. Morning snacks were more popular among children vs. adolescents and contributed significantly less energy than afternoon or evening snacking periods for both age groups (P < 0.001). The top food groups consumed as snacks were the same for children and adolescents, although the ranking order varied. Fruits were the leading food group in terms of per capita energy for children and second for adolescents. Aside from fruits and milks, all other top per capita energy contributors were generally more energy-dense, nutrient-poor foods such as cookies, biscuits and cereal bars, and other breads. Among children, morning snacks were higher in desirable nutrients compared with afternoon snacks. Not all snacking periods are equal in terms of energy and nutrients. A better understanding of how time of day may influence the quality of snack foods can inform meal-based guidance and help children achieve the recommended daily amounts of foods and nutrients.