Applied Physiology, Nutrition, and Metabolism最新文献

The objectives of our study were to examine recreational screen time behavior before and 2 years following the COVID-19 pandemic lockdown, and explore whether components of the capability-opportunity-motivation-behavior (COM-B) model would predict changes in this recreational screen time behavior profile over the 2-year period. This cross-sectional, retrospective study was conducted in March 2022. Canadian adults (n = 977) completed an online survey that collected demographic information, current screen time behavior, screen time behavior prior to the pandemic, and beliefs about capability, opportunities, and motivation for limiting screen time based on the COM-B model. We found that post-pandemic recreational screen time (3.91 ± 2.85 h/day) was significantly higher than pre-pandemic levels (3.47 ± 2.50 h/day, p < 0.01). Three recreational screen time behavior profiles were identified based on the Canadian 24-Hour Movement Guidelines: (1) always met screen time guidelines (≤3 h/day) (47.8%; n = 454); (2) increased screen time (10.1%; n = 96); and (3) never met screen time guidelines (42%; n = 399). The overall discriminant function was found to be significant among the groups (Wilks' λ = 0.90; canonical r = 0.31, χ² = (14) = 95.81, p < 0.001). The group that always met screen time guidelines had the highest levels of automatic motivation, reflective motivation, social opportunity, and psychological capabilities to limit screen time compared to other screen time profile groups. In conclusion, recreational screen time remains elevated post-pandemic. Addressing motivation (automatic and reflective), psychological capabilities, and social opportunities may be critical for future interventions aiming to limit recreational screen time.

The immune system requires an adequate supply of nutrients, although current dietary recommendations may not account for optimal immune function in healthy adults. Nutrient inadequacies due to the growing influence of the western diet pose a risk for immune dysfunction. This review aims to determine the beneficial effects of supplementing dietary fats, nutrients that modulate gut microbiota, and specific micronutrients on systemic immune functions (concentrations of plasma cytokines, antibodies, and acute phase proteins) during health and acute inflammatory conditions, including COVID-19. We discussed micronutrients (selenium, zinc, and vitamin D) with compelling evidence supporting immunomodulatory properties. Additionally, the synergistic effects of physical activity and dietary interventions on systemic immune markers are explored. Briefly, evidence suggests that dietary consumption of monounsaturated (oleic and palmitoleic acids) and omega-3 polyunsaturated fatty acids (eicosapentaenoic and docosahexaenoic acids) promotes anti-inflammatory properties. Food sources (fiber, prebiotics, probiotics, omega-3) and patterns (Mediterranean diet) increase the production of short-chain fatty acids, beneficially altering gut microbiota composition, which subsequently enhances the immunomodulatory properties of circulating immune cells. A positive synergistic role of nutrient supplementation (omega-3 and fiber) and physical activity on circulating C-reactive protein and interleukin-6 levels has been observed. Lastly, omega-3 supplementation during COVID-19 infection may reduce circulating C-reactive protein and pro-inflammatory cytokines and improves pain and fatigue symptoms. This review highlights recent findings that support the beneficial role of specific nutrients in promoting systemic immune function in healthy adults. However, to establish specific dietary recommendations to support optimal immune function, more research is required. Key takeaway: Increasing dietary fats (fish and olive oils) and specific micronutrients may positively impact systemic immune function in healthy adults. Evidence suggests that these nutrients promote immunomodulatory properties useful in resolving acute infection.

The economic cost associated with low muscle strength in Canadian adults is unknown. The total annual economic burden of low muscle strength in Canadian adults represents 2.2% of the overall burden of illness costs in 2021. We estimated that $546 million per year would be saved if the prevalence of low handgrip strength was reduced by 10%.

The perception of dyspnea is influenced by both physiological and psychological factors. We sought to determine whether exertional dyspnea perception could be experimentally manipulated through prior exposure to heightened dyspnea while exercising. We hypothesized that dyspnea perception during exercise would be lower following an induced dyspnea task (IDT). Sixteen healthy participants (eight females, eight males) completed two days of exercise testing. Day 1 involved an incremental cycle exercise test starting at 40 W for females and 60 W for males, increasing by 20 W each minute until volitional exhaustion. Following the maximal exercise test on Day 1, participants completed IDT, involving 5 min of exercise at 70% of peak work rate with 500 mL dead space and external resistance (i.e., 6.8 ± 2.3 cm·H₂O·s^-1·L^-1 inspiration, 3.8 ± 0.7 cm·H₂O·s^-1·L^-1 expiration). Day 2 consisted of an incremental exercise test identical to Day 1. At maximal exercise, there were no differences in oxygen uptake (V̇O₂; 44.7 ± 7.7 vs. 46.5 ± 6.3 mL·kg^-1·min^-1), minute ventilation (120 ± 35 vs. 127 ± 38 L·min^-1), dyspnea (6.5 [4, 8.5] vs. 6 [4.25, 8.75]), or leg discomfort (6 [5, 8.75] vs. 7 [5, 9]) between days (all p > 0.05). At 60%-80% of peak V̇O₂ (V̇O_2peak), dyspnea was significantly lower on Day 2 (-0.75 [-1.375, 0] for 60% and -0.5 [0, -2] for 80%, p < 0.05) despite no differences in relevant physiological variables. The onset of perceived dyspnea occurred at a significantly higher exercise intensity on Day 2 than on Day 1 (42% ± 19% vs. 51% ± 17% V̇O_2peak, respectively; p < 0.05). Except for 40% V̇O_2peak (p = 0.05), RPE-L was not different at any intensities nor was the onset of perceived leg discomfort different between days (38% ± 14% vs. 43% ± 10% V̇O_2peak, respectively; p = 0.10). Exposure to heightened dyspnea alters exercise-induced dyspnea perception during subsequent submaximal exercise bouts.

Sarcopenia is associated with falls, and can complicate recovery following total joint replacement (TJR) surgery. We examined (1) the prevalence of sarcopenia indicators and lower-than-recommended protein intake among TJR patients and non-TJR community participants and (2) the relationships between dietary protein intake and sarcopenia indicators. We recruited adults ≥65 years of age who were undergoing TJR, and adults from the community not undergoing TJR (controls). We assessed grip strength and appendicular lean soft-tissue mass (ALSTM_BMI) using DXA, and applied the original Foundation for the National Institutes of Health Sarcopenia Project cut-points for sarcopenia indicators (grip strength <26 kg for men and <16 kg for women; ALSTM <0.789 m² for men and <0.512 m² for women) and less conservative cut-points (grip strength <31.83 kg for men and <19.99 kg for women; ALSTM <0.725 m² for men and <0.591 m² for women). Total daily and per meal protein intakes were derived from 5-day diet records. Sixty-seven participants (30 TJR, 37 controls) were enrolled. Using less conservative cut-points for sarcopenia, more control participants were weak compared with TJR participants (46% versus 23%, p = 0.055), and more TJR participants had low ALSTM_BMI (40% versus 13%, p = 0.013). Approximately 70% of controls and 76% of TJR participants consumed <1.2 g protein/kg/day (p = 0.559). Total daily dietary protein intake was positively associated with grip strength (r = 0.44, p = 0.001) and ALSTM_BMI (r = 0.29, p = 0.03). Using less conservative cut-points, low ALSTM_BMI, but not weakness, was more common in TJR patients. Both groups may benefit from a dietary intervention to increase protein intake, which may improve surgical outcomes in TJR patients.

The trace element selenium, which is found in selenoproteins, plays an antioxidant role in preventing muscle tissue injury. A positive association between selenium concentrations and hand grip strength has been reported in older adults; however, the evidence of this association is scarce in general adults. In this study, we aimed to evaluate the association between blood selenium concentrations and low hand grip strength using the data from the National Health and Nutrition Examination Survey 2011-2012 and 2013-2014 in the United States (US). Logistic regression was used to calculate the odds ratio (OR) of low hand grip strength, with blood selenium level adjusted for potential confounders. Among 8158 adults (women: 51.59%) with a mean age of 47 (range: 18-80) years, women and non-Hispanic Blacks tended to have low blood selenium concentrations. Notably, participants with high blood selenium concentrations (range, 178.1-192.5 µg/L) were more likely to have a low risk of low hand grip strength after adjusting for the potential covariates (OR: 0.60, 95% confidence interval (CI): 0.38-0.95) than those with low blood selenium concentrations. After excluding participants with chronic diseases, high blood selenium concentrations were found to be associated with a low risk of low hand grip strength (OR: 0.30, 95% CI: 0.14-0.65). A J-shaped relationship was found between selenium concentrations and low hand grip strength (P for nonlinear trend <0.0001). Subgroup analyses revealed a significantly consistent relationship among women, non-Hispanic Whites and others, and individuals with overweight or obesity (P < 0.05). Our study suggests that blood selenium concentrations are inversely associated with hand grip strength in general US adults. However, further prospective studies are required to confirm the causality between selenium concentrations and hand grip strength.

The purpose of this study was to determine (1) whether pulmonary function is reduced, and airway reactivity is increased after recovery from COVID-19 in individuals who did not have severe illness, and (2) whether physical activity levels had any impact on pulmonary function or airway reactivity. An exploratory aim of the study was also to assess whether number of symptoms was associated with pulmonary function outcomes. The maximal flow volume loop was used to measure pulmonary function in individuals who had previously tested positive for COVID-19 (COV; n = 20, 23.0 ± 5.4 years) and those who had not (CON; n = 20, 23.7 ± 5.5 years) before and after a hypertonic saline challenge (HSC) designed to increase airway reactivity. Self-reported symptoms and physical activity levels (MET (min/week)) were collected to examine their correlation with pulmonary outcomes. There were no significant differences in any pulmonary function outcomes between the COV and CON groups before or after the HSC. There were also no associations between physical activity and pulmonary function outcomes. However, among participants who reported greater than four symptoms, there was a larger decline in forced expiratory volume in 1 s divided by forced vital capacity following HSC (p = 0.035). Pulmonary function and airway reactivity are not impacted after recovery from COVID-19 in young individuals; however, it appears that the number of symptoms reported may be associated with increased airway reactivity even after recovery in young adults who were not hospitalized with the virus.

In January 2022, a group of experts came together to discuss current perspectives and future directions in nutritional immunology as part of a symposium organized by the Canadian Nutrition Society. Objectives included (1) creating an understanding of the complex interplay between diet and the immune system from infants through to older adults, (2) illustrating the role of micronutrients that are vital to the immune system, (3) learning about current research comparing the impact of various dietary patterns and novel approaches to reduce inflammation, autoimmune conditions, allergies, and infections, and (4) discussing select dietary recommendations aimed at improving disease-specific immune function. The aims of this review are to summarize the symposium and to identify key areas of research that require additional exploration to better understand the dynamic relationship between nutrition and immune function.

We examined postprandial branched-chain amino acid (BCAA), insulin, and glucose responses in blood for 4 h following the consumption of two isonitrogenous doses (2 × 20 g protein) of Greek-style yogurt (GY) and skimmed milk (MILK) in young males. Peak leucine and BCAA concentrations and areas under the curve were greater after GY versus MILK, and time to maximal leucine/BCAA concentrations was similar between conditions. We demonstrated that different protein-matched wholefood dairy products elicit different postprandial aminoacidemic responses.