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

High-intensity exercise increases inflammation and elicits leukocytosis but may also increase infection risk. Interestingly, females have higher cell-mediated immunity than males. Sex hormones fluctuate across the menstrual cycle (MC), and the luteal phase has been linked to a more pro-inflammatory environment than the follicular phase. This study investigated whether white blood cell (WBC) count and WBC differential (i.e., neutrophils, lymphocytes, monocytes, eosinophils, and basophils) differed across two MC phases following an acute bout of exercise that varied in intensity. Eight regularly menstruating females (age = 21.6 ± 3.0; BMI = 20.9 ± 4.1 kg/m²) completed a $\dot{V}{\text{O}}_2$ peak (37.8 ± 11.0 mL/min/kg) test and two 40 min cycling exercise trials (30 min of moderate intensity (%HRmax = 71.13 ± 8.5, % $\dot{V}{\text{O}}_2$ peak = 49.8 ± 21.6) and ∼10 min of high intensity (%HRmax = 93.3 ± 6.7, % $\dot{V}{\text{O}}_2$ peak = 75.4 ± 27.6)) 14 ± 2 days apart. Blood samples were taken pre- and post-moderate-intensity exercise (30 min), as well as immediately post-high-intensity exercise (∼40 min). Both moderate- and high-intensity exercise increased WBC counts (p < 0.01, (d = 1.11 and 1.34, respectively)). More specifically, neutrophil counts increased following both moderate (p < 0.05, d = 0.72) and high (p < 0.01, d = 0.95) exercise intensities. However, lymphocytes (p < 0.01, d = 1.15) and monocytes (p < 0.01, d = 0.99) were only elevated following high-intensity exercise. MC phase did not significantly alter WBC counts nor differentials, although there were trends observed towards greater leukocytosis at moderate-intensity exercise during the luteal phase. These results demonstrate that in some cases moderate-intensity exercise increased leukocytosis (in particular, neutrophils), while high-intensity exercise resulted in significant leukocytosis primarily as a result of increased neutrophils, lymphocytes, and monocytes. Future research should investigate this relationship in a larger sample observing inflammatory cytokines and WBC function/activity with the inclusion of a group in the early follicular phase.

Irisin, an adipo-myokine, is positively associated with cardiorespiratory fitness and negatively associated with type 2 diabetes mellitus (T2DM). However, it is unclear if individuals with longer or shorter durations of T2DM express the same irisin levels following exercise. The objective of this study is to investigate the impact of 28 weeks of moderate-to-vigorous intensity aerobic exercise on irisin levels in individuals with short- and long-duration T2DM. This secondary analysis included participants (n = 34) aged ≥ 19 years old with T2DM who completed 28 weeks of aerobic exercise training for 150 min per week at a moderate-to-vigorous intensity-16 weeks at a moderate intensity (4.5 metabolic equivalents of tasks (METs)) and then randomized to 12 weeks of maintained-intensity (4.5 METs) or increased-intensity (6.0 METs) aerobic exercise. Participants were categorized into two groups: (1) short-duration T2DM (<10 years) or (2) long-duration T2DM (≥10 years). Irisin was analyzed using enzyme-linked immunosorbent assay and western blotting techniques. All measurements were performed at baseline, 16 weeks, and 28 weeks. A significant time × T2DM duration group interaction (F(2) = 8.062, p < 0.01) was observed with 28 weeks of moderate-to-vigorous intensity aerobic exercise. Western blot analysis revealed a 1.37-fold increase in plasma irisin expression (p = 0.03) in the long-duration increased-intensity group and no change in irisin expression (p > 0.05) in the maintained-intensity groups of short and long duration. The results of this analysis suggest that 28 weeks of moderate-to-vigorous intensity aerobic exercise differently impacted plasma irisin in individuals with short- or long-duration T2DM. The Improving Individual Glycemic Response with Exercise Intensity (INTENSITY) study was registered at clinicaltrials.gov (NCT03787836).

We assessed how different levels of breast support affected exertional symptoms and respiratory responses in small- and large-breasted females during treadmill exercise. Twenty recreationally-active females (mean ± SD age: 22 ± 2 years) were divided into small (SBV: 322±77 mL) and large breast volume (LBV: 580±88 mL; p < 0.001, g = 2.98) groups. Participants completed three 5 min bouts of treadmill exercise at 30%, 60%, and 90% of individual peak power output (PPO)-corresponding to walking, low-intensity running, and high-intensity running-wearing either a high-support or low-support sports bra (randomized). Measurements included cardiorespiratory variables, operating lung volumes, inspiratory muscle electromyographic, respiratory muscle pressures, breast acceleration, and exertional symptoms (breathlessness, chest tightness due to bra). High- versus low-support sports bras reduced mean breast acceleration (p < 0.001, ${\eta }_p^2$ =0.55), but evoked higher ratings of chest tightness (p = 0.040, ${\eta }_p^2$ =0.16) in LBV participants at low- and high-intensity running (g = 1.09 and g = 0.99, respectively). Although breathlessness was not significantly different by bra or breast volume (all p > 0.05), LBV participants consistently reported breathlessness intensity and unpleasantness ≥ 1 Borg unit (BU) higher than SBV participants during low- and high-intensity running (breathlessness intensity: ∼5 vs. ∼3 BU at 60% PPO; ∼9 vs. ∼7 BU at 90% PPO; breathlessness unpleasantness: ∼4 vs. ∼2 BU at 60% PPO, ∼8 vs. ∼6 BU at 90% PPO). There were no differences in cardiorespiratory variables, inspiratory muscle activity, operating lung volumes between breast volume groups or sports bras (all p > 0.05). We emphasize the importance of addressing subjective discomfort, including chest tightness and breathlessness, when developing effective breast support for weight-bearing exercise, especially for larger-breasted individuals.

With climate warming, there is an urgent need to understand the health effects of occupational heat exposure. This systematic review examined the cumulative effects of consecutive days of prolonged physical work or activity on heat strain and physical performance. Electronic databases MEDLINE, SPORTDiscus, PsychInfo, and Academic Search Complete were searched until July 2024 with terms related to work, consecutive days, and heat. Studies were included if they involved ≥4 h of physical work/activity on ≥2 consecutive days, and included a measure of heat strain (e.g., core temperature) or physical performance (e.g., repetitions). After removing duplicates, 6030 studies were screened (title and abstract), 133 progressed to full-text screening, and 33 met the inclusion criteria with risk of bias assessed. However, only five studies used standardized environmental and work conditions across days. Synthesis of the cumulative effects (without meta-analysis) was therefore restricted to these studies. None observed a cumulative impact on heat strain, as indexed by a higher core temperature or heart rate compared to day 1. None reported a reduction in physical task performance across days. These findings indicate that the cumulative effects of occupational heat exposure on heat strain and physical task performance were minimal, although evidence supporting this conclusion is sparse. PROSPERO registration: CRD42023452936.

As a novel, low-velocity resistance exercise method, eccentric quasi-isometric resistance exercise (EQI-RE) results in greater time under tension than traditional isotonic resistance exercise (TRD-RE) and is surmised to increase muscle mass and strength. However, females may be more fatigue-resistant than males when performing acute EQI-RE, which could lead to long-term differences in time under tension and resistance exercise volume. At present, studies have yet to compare muscle hypertrophy or strength improvements following TRD-RE and EQI-RE training, and whether sex differences exist in these outcomes. Twenty-two (n = 13 females) untrained individuals completed ∼8 weeks of effort matched unilateral TRD-RE and EQI-RE of the elbow flexors. Muscle thickness and estimated one-repetition maximum (E-1RM) were evaluated before and after training. TRD-RE produced significantly larger relative increases in muscle thickness (6.7% ± 3.9% vs. 4.0% ± 3.3%, p = 0.004) and E-1RM (19.6 ± 8.5% vs. 12.8 ± 6.2%, p = 0.001) than EQI-RE. Although females accrued greater resistance exercise volume than males across the TRD-RE and EQI-RE training, there were no relative sex differences in muscle thickness or E-1RM improvements (p > 0.25). Sex differences in fatiguability may therefore manifest in differences in resistance exercise volume between males and females after 8 weeks of TRD-RE and EQI-RE of the elbow flexors, but this does not lead to relative differences in muscle thickness or E-1RM improvements. Although EQI-RE did produce significant increases, TRD-RE of the elbow flexors appears more effective at increasing muscle thickness and E-1RM.

Previous research has demonstrated attenuated exercising carbohydrate oxidation and circulating glucose when endurance athletes are functionally overreached; however, whether free-living glycemic control is altered with overreaching is unknown. Trained endurance athletes (M:8, F:2) completed a 5-week training protocol composed of three phases: 1 week of reduced training, 3 weeks of high-intensity overtraining, and 1 week of recovery training. Participants wore continuous glucose monitors (CGM) to collect minute-by-minute interstitial glucose concentrations, and data were analyzed for weeks 1 (PRE), 4 (POST), and 5 (REC). A fasted 75 g oral glucose tolerance test (OGTT) was performed at the end of each phase with repeated capillary sampling to measure glucose concentrations. CGM-derived 24 h average glucose, overnight average glucose (12  am to 6  am), and daily time spent in low (<3.9 mmol/L), normal (3.9-5.0 mmol/L), and medium-high (5.1-7.8 mmol/L) glucose ranges were not different across training phases. The proportion of time with elevated interstitial glucose (>7.8 mmol/L) was elevated at REC (3.5 ± 1.1%) relative to PRE (2.4 ± 1.9%, P = 0.05) and POST (2.1 ± 1.0%, P = 0.021; ηp² = 0.66). The daily mean amplitude of glycemic excursions also increased at REC (2.6 ± 0.2 mmol/L) relative to PRE (2.3 ± 0.3 mmol/L, P = 0.05) and POST (2.2 ± 0.3 mmol/L, P = 0.008; ηp² = 0.41). Capillary glucose area-under-the-curve was nonsignificantly reduced from PRE (852.5 ± 87.6 mmol/L·min) to POST (811.4 ± 77.5 mmol/L·min, P = 0.06), and elevated from POST-to-REC (866.3 ± 79.8 mmol/L·min, P = 0.02; ηp² = 0.3) during the OGTT. Glycemic control and glucose tolerance are unchanged with overtraining; however, following a week of recovery there is greater time spent with elevated glucose and greater glucose variability suggesting disrupted glycemic control during recovery.

Malnutrition is prevalent among older adults in Canada and it can be mitigated through personalized dietitian-led counselling. This qualitative study aimed to explore how malnutrition is communicated and perceived, providing insight for future care. This multisite qualitative study was conducted in Alberta and Quebec, Canada. Participants were recruited through purposive sampling to target patients ≥65 years old who spoke French or English, had a malnutrition diagnosis, and received counseling for malnutrition from a dietitian. Dietitians who had worked directly with patients ≥65 years old with a diagnosis of malnutrition were recruited through advertisement. Semi-structured interviews were recorded both in person and over the phone. Data were transcribed verbatim and analyzed using reflexive thematic analysis. Twenty-five patients and 10 dietitians were interviewed, producing five themes (two dietitian themes and three patient themes). First, diagnosing malnutrition: dietitians highlighted challenges in diagnosing malnutrition due to limited support and resources. Second, using the "M" word: dietitians hesitated to use the term "malnutrition" with patients. Third: knowing I'm malnourished: patients reported not being informed of their diagnosis. Fourth, what is malnutrition? Patients revealed the word sounds extreme and unrelatable. Reactions to the diagnosis varied: acceptance, shock, detached, and neutral. Finally, stigma and blame: some patients distanced themselves from the stigma by rationalizing their nutrition problems. Gaps in management of malnutrition were identified. Future research should focus on how to communicate the diagnosis to improve outcomes for malnutrition.