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

Skeletal muscle echo intensity (EI) is affected by ageing and physical activity; however, the effects of nutrition are less understood. The aim of this study was to explore whether habitual nutrient intake may be associated with ultrasound-derived EI. Partial least squares regression (PLSR) models were trained on an initial sample (n = 100, M = 45; F = 55; 38 ± 15 years) to predict EI of two quadriceps muscles from 19 variables, using the "jack-knife" function within the "pls" package (RStudio), which was then tested in an additional dataset (n = 30, M = 13; F = 17; 38 ± 16 years). EI was determined using B-mode ultrasonography of the rectus femoris (RF) and vastus lateralis (VL) and nutritional intake determined via 3-day weighed food diaries. Mean daily intake of specific nutrients were included as predictor variables with age, sex, and self-reported physical activity. PLSR training model 1 explained ∼52% and model 2 ∼46% of the variance in RF and VL EI, respectively. Model 1 also explained ∼35% and model 2 ∼30% of the variance in RF and VL EI in the additional testing dataset. Age and biological sex were associated with EI in both models (P < 0.025). Dietary protein (RF: β = -7.617, VL: β = -7.480), and selenium (RF: β = -7.144, VL: β = -4.775) were associated with EI in both muscles (P < 0.05), whereas fibre intake (RF: β = -5.215) was associated with RF EI only and omega-3 fatty acids (n-3/ω-3 FAs, RF: β = 3.145) with VL EI only (P < 0.05). Therefore, absolute protein, selenium, fibre, and n-3 FAs may be associated with skeletal muscle EI, although further mechanistic work is required before claiming causal inference.

Carbohydrate (CHO) and caffeine (CAF) mouth rinsing have been independently reported to benefit sport performance. The proposed mechanisms by which mouth rinsing CHO exerts an influence are reported to be different from those for mouth rinsing CAF. However, the potential ergogenic effects of combining CHO and CAF in a single mouth rinse solution, are unclear. This study aimed to review the available evidence of CHO-CAF combined mouth rinse on exercise and cognitive performance in human participants. A systematic literature search was conducted using five databases until April 2024, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) recommendations. Among the nine randomized crossover studies included, only one study showed significant improvements in lower-body muscular endurance with CHO-CAF mouth rinse (effect size (ES): 0.48; p < 0.05), while two studies reported non-statistically significant improvements in repeated sprint performance compared to other mouth rinse and placebo conditions (ES: 0.20-0.81; p = 0.07-0.18). However, for other performance measures, including repeated jumps, upper-body strength and endurance, endurance cycling, and intermittent recovery run, most evidence (five studies) did not demonstrate significant ergogenic effects. Notably, of the two studies that examined cognitive performance, both reported significant improvements with CHO-CAF mouth rinse compared with the placebo condition (ES: 0.45-3.45; p < 0.05). Overall, a synergistic influence of CHO-CAF mouth rinse on physical exercise performance is not evident, but preliminary evidence suggests potential benefits on cognitive performance. Future studies are required to address various methodological issues identified in this review, while practitioners and athletes should exercise caution when considering this novel nutritional strategy.

Resistance training (RT) promotes skeletal muscle (Skm) hypertrophy, increases muscular strength, and improves metabolic health. Whether changes in fat-free mass (FFM; a surrogate marker of muscle hypertrophy) moderate RT-induced improvements in glucose homeostasis has not been determined, despite extensive research on the benefits of RT for health and performance. The aim of this meta-analysis is to examine whether RT-induced Skm hypertrophy drives improvements in glucose metabolism and to explore confounders, such as biological sex and training parameters. Random-effects meta-analyses were performed using variance random effects. Meta-regressions were performed for confounding factors depending on the heterogeneity (I²). Analyses from 33 intervention studies revealed significant within-study increases in FFM with a moderate effect size (within-studies: (effect size; ES = 0.24 [0.10; 0.39]; p = 0.002; I² = 56%) and a tendency for significance when compared with control groups (ES = 0.42 [-0.04-0.88]; p = 0.07). Within-study significant increases in glucose tolerance (2 h glucose: ES = -0.3 [-0.50; -0.11]; p < 0.01; I² = 43%; glucose area under the curve (AUC): -0.40 [-0.66; -0.13] I² = 76.1%; p < 0.01) and insulin sensitivity (ES = 0.38 [0.13; 0.62]; I² = 53.0%; p < 0.01) were also apparent with RT. When compared to control groups, there was no significant difference in 2 h glucose, nor in glucose AUC from baseline in RT intervention groups. Meta-regression analyses failed to consistently reveal increases in FFM as a moderator of glucose homeostasis. Other mixed-effect models were also unsuccessful to unveil biological sex or training parameters as moderators of FFM increases and glucose homeostasis changes. Although Skm hypertrophy and improvements in glycemic control occur concurrently during RT, changes in these variables were not always related. Well-controlled trials including detailed description of training parameters are needed to inform RT guidelines for improving metabolic health. Registration and protocol number (Prospero): CRD42023397362.

Affective experiences have been shown to influence attitudes and future behaviors related to physical activity, but no studies have related these experiences to physical literacy or examined affective experiences in quality physical education (QPE). The aim of this study was to describe emotions experienced in a QPE context and relate those emotions to students' physical literacy and self-esteem. A cross-sectional study of 145 4th and 5th grade students was surveyed after a single PE class on their emotional experiences (positive emotions: pride, enjoyment, and relief; negative, emotions: shame, anger, and boredom; aggregate emotional experience as the sum of positive and negative emotions) physical literacy (self-description and movement valuation) and self-esteem. In this QPE context, 73% of students reported only positive emotions, 26% mixed positive and negative emotions and 1% expressed only negative emotions. Pride and enjoyment were strongly co-occurring (89%). Among students expressing mixed emotions, 90% still yielded positive aggregate emotional experiences. Positive emotions have significant (p < 0.001), moderate to strong positive correlations with physical literacy (rho = 0.65 pride, 0.50 enjoyment) and self-esteem (rho = 0.48 pride, 0.38 enjoyment), and negative emotions have significant (p < 0.001), moderate negative correlations with physical literacy (rho = -0.47 shame, -0.30 anger, -0.32 boredom) and self-esteem (rho = -0.33 shame, -0.29 anger, -0.21 boredom). This study reveals strong positive emotional responses by students in a purported QPE context. The presence of mixed emotions with net positive aggregate experiences highlights the importance of consideration of both negative and positive emotions in movement contexts. Affective states have been proposed as key elements of physical literacy, and this study supports this through valence matched associations between both positive/negative affect with physical literacy and self-esteem.

Plant-based food demand is rapidly increasing. However, the metabolic responses of plant proteins within their commercially available form remains unclear. Two randomized crossover experiments compared plant-based alternatives to dairy on postprandial glycemia, metabolic hormones, and appetite before and after a fixed size (12 kcal/kg body weight) pasta meal in sixteen healthy young adults (eight males and eight females). In experiment one, participants (22.8±2.3y) consumed one-serving of Greek yogurt (175g), cheddar cheese (30g), plant-based cheese (30g), or plant-based yogurt (175g). In experiment two, participants (22.3±2.4y) consumed one-serving (250 mL) of cow's milk, vanilla soy beverage or vanilla almond beverage, and (30 g) of cheddar cheese or plant-based cheese. Blood glucose, insulin, and appetite were measured at baseline, post-treatment, and following a fixed-size pasta meal (post-meal) within 15-30 min. In experiment two, C-peptide, GLP-1, and ghrelin were measured. Greek yogurt and cheddar cheese lowered post-meal blood glucose more than their plant-based alternatives (p <0.01) and post-treatment blood glucose was higher following almond beverage than cheddar cheese and plant-based cheese (p <0.01). In experiment 1, post-treatment insulin was higher after Greek yogurt than cheddar cheese and plant-based cheese and all treatments post-meal (p <0.02). Post-meal appetite was lower after plant-based yogurt than cheddar cheese and plant-based cheese (p <0.01). In experiment 2, post-treatment insulin was higher after almond beverage compared to all treatments (p <0.01) and post-meal GLP-1 was higher after milk than almond beverage (p =0.03). We conclude that the physiological functionality of plant-based alternatives as measured by blood glucose, insulin, C-peptide, and GLP-1 did not replicate the metabolic functions of dairy products.

We compared two methods of partitional calorimetry to calculate heat storage and heat debt during cold air (0°C) exposure causing mild core cooling. Twelve participants performed a 5 min baseline in thermoneutral conditions (∼22.0°C, ∼50% relative humidity) followed by cold air exposure (∼0°C) until rectal temperature was reduced by ∆-0.5°C. Partitional calorimetry was used to calculate avenues of heat exchange (radiative, convective, and evaporative), heat storage, and heat debt continuously throughout cold exposure. We compared deriving these variables using prediction equations based on environmental and participant characteristics (PCAL_{Equation Method}) versus using measurement tools such as humidity sensors and heat flux discs (PCAL_{Heat Flux Method}). There were significant differences between methods (all p ≤ 0.001) for determining heat exchange, heat storage, and heat debt. At ∆-0.5°C, PCAL_{Heat Flux Method} had greater levels of radiative and convective heat exchange (PCAL_{Heat Flux Method}: -143.0 ± 16.8 W∙m² vs PCAL_{Equation Method}: -123.0 ± 12.9 W∙m², p ≤ 0.001), evaporative heat exchange (PCAL_{Heat Flux Method}: -9.0 ± 1.7 W∙m² vs PCAL_{Equation Method}: -4.1 ± 0.0 W∙m², p ≤ 0.001), heat storage (PCAL_{Heat Flux Method}: -15.0 ± 31.0 W∙m² vs PCAL_{Equation Method}: +6.0 ± 25.9 W∙m², p = 0.020), and heat debt (PCAL_{Heat Flux Method}: -692.0 ± 315.0 kJ vs PCAL_{Equation Method}: -422.0 ± 136.0 kJ, p ≤ 0.001). Overall, this study found the largest discrepancies between the two methods were when the environmental conditions and skin temperature were in high flux, as well as when core temperature was reduced by ∆-0.5°C. The use of PCAL_{Heat Flux Method} may be more advantageous to use in the cold to provide a higher resolution measurement of cold strain.

Foot immersion and neck cooling are recommended cooling strategies for protecting heat-vulnerable persons during heat waves. While we recently showed that these strategies do not limit core temperature increases in older adults during prolonged heat exposure, we did observe small reductions in heart rate. Expanding on these findings, we examined the effects of foot immersion with and without neck cooling on cardiac autonomic function. Seventeen adults (9 females; 65-81 years) underwent 3 randomized, 6 h exposures to 38 °C and 35% relative humidity with: no cooling (control), foot immersion (20 °C water), or foot immersion with a wet towel (20 °C) around the neck. Cardiac autonomic responses were measured at baseline and end-exposure. These included heart rate variability, cardiac and systolic blood pressure responses to standing, indexed via the 30:15 ratio and supine-to-standing systolic pressure change, respectively, and baroreflex sensitivity during repeated sit-to-stand maneuvers. The 30:15 ratio was 0.04 [95% CI: 0.01, 0.07] greater with foot immersion and neck cooling (1.08 (SD: 0.04)) relative to control (1.04 (0.06); P = 0.018). Similarly, standing systolic blood pressure was elevated 9 [0, 17] mmHg with foot immersion and neck cooling (P = 0.043). That said, neither difference remained statistically significant after adjusting for multiplicity (P_adjusted ≥ 0.054). No differences in 30:15 ratio or standing systolic blood pressure were observed with foot immersion alone, while heart rate variability and baroreflex sensitivity were unaffected by either cooling intervention. While foot immersion with neck cooling potentially improved cardiac autonomic responses in older adults exposed to simulated indoor overheating, these effects were small and of questionable clinical importance.

Intense exercise training with insufficient recovery time is associated with reductions in neuromuscular performance. However, it is unclear how single muscle fibre mechanical function and myofibrillar Ca²⁺ sensitivity contribute to these impairments. We investigated the effects of overload training on joint-level neuromuscular performance and cellular-level mechanical function. Fourteen athletes (4 female and 10 male) underwent a 3-week intensified training protocol consisting of up to 150% of their regular training hours with three additional high-intensity training sessions per week. Neuromuscular performance of the knee extensors was assessed via maximal voluntary contraction (MVC) force, electrically evoked twitch contractions, and a force-frequency relationship. Muscle biopsies were taken from the vastus lateralis to assess single fibre mechanical function. Neither MVC force nor twitch parameters were altered following training (all p > 0.05), but a rightward shift in the force-frequency curve was observed with average reduction in force of 6%-27% across frequencies 5-20 Hz (all p < 0.05). In single fibres, maximal force output was not reduced following training, but there was a rightward shift in the force-pCa curve driven by a 6% reduction in Ca²⁺ sensitivity (p < 0.05). These data indicate intensified training leads to impaired Ca²⁺ sensitivity at the single fibre level, which in part explains impaired neuromuscular function at the joint level during lower frequencies of activation. This is an important consideration for athletes, as performance is often assessed at maximal levels of activation, and these underlying impairments in force generation may be less obvious.

Disabling atrial fibrillation (AF)-related symptoms and different testing settings may influence day-to-day cardiopulmonary exercise testing (CPET) measurements, which can affect exercise prescription for high-intensity interval training (HIIT) and moderate-to-vigorous intensity continuous training (M-VICT) and their outcomes. This study examined the reliability of CPET in patients with AF and assessed the proportion of participants achieving minimal detectable changes (MDC) in peak oxygen consumption (V̇O_2peak) following HIIT and M-VICT. Participants were randomized into HIIT or M-VICT after completing two baseline CPETs: one with cardiac stress technologists (CPET_diag) and the other with a research team of exercise specialists (CPET_research). Additional CPET was completed following 12 weeks of twice-weekly training. The reliability of CPET_diag and CPET_research was assessed by intraclass correlation coefficient (ICC) and dependent t tests. The MDC score was calculated for V̇O_2peak using a reliable change index. The proportion of participants achieving MDC was compared between HIIT and M-VICT using chi-square analysis. Eighteen participants (69 ± 7 years, 33% females) completed two baseline CPETs. The ICCs were significant for all measured variables. However, peak power output (PO_peak: 124 ± 40 vs. 148 ± 40 watts, p < 0.001) and HR (HR_peak: 136 ± 22 vs. 148 ± 30 bpm, p = 0.023) were significantly greater in CPET_research than CPET_diag. Few participants achieved MDC in V̇O_2peak (5.6 mL/kg/min) with no difference between HIIT (0%) and M-VICT (10.0%, p = 0.244). PO_peak and HR_peak differed significantly in patients with AF when CPETs were repeated under different settings. Caution must be practised when prescribing exercise intensity based on these measures as under-prescription may increase the number of exercise non-responders.

This study investigated sex-specific differences in high-energy phosphate, glycolytic, and mitochondrial enzyme activities and also metabolite transporter protein levels in the skeletal muscles of adult (5 months old), middle-aged (12 months old), and advanced-aged (24 months old) mice. While gastrocnemius glycogen content increased with age regardless of sex, gastrocnemius triglyceride levels increased only in advanced-aged female mice. Aging decreased creatine kinase and adenylate kinase activities in the plantaris muscle of both sexes and in the soleus muscle of male mice but not in female mice. Irrespective of sex, phosphofructokinase and lactate dehydrogenase (LDH) activities decreased in the plantaris and soleus muscles. Additionally, hexokinase activity in the plantaris muscle and LDH activity in the soleus muscle decreased to a greater extent in aged male mice compared with those in aged female mice. Mitochondrial enzyme activities increased in the plantaris muscle of aged female mice but did not change in male mice. The protein content of the glucose transporter 4 in the aged plantaris muscle and fatty acid translocase/cluster of differentiation 36 increased in the aged plantaris and soleus muscles of both sexes, with a significantly higher content in female mice. These findings suggest that females possess a better ability to maintain metabolic enzyme activity and higher levels of metabolite transport proteins in skeletal muscle during aging, despite alterations in lipid metabolism. Our data provide a basis for studying muscle metabolism in the context of age-dependent metabolic perturbations and diseases that affect females and males differently.