Inspiratory muscle training enhances pulmonary O2 uptake kinetics and high-intensity exercise tolerance in humans

Fatigue of the respiratory muscles during intense exercise might compromise leg blood flow, thereby constraining oxygen uptake (VO2) and limiting exercise tolerance. We tested the hypothesis that inspiratory muscle training (IMT) would reduce inspiratory muscle fatigue, speed VO2 kinetics and enhance exercise tolerance. Sixteen recreationally active subjects (mean ± SD, age 22 ± 4 yr) were randomly assigned to receive 4 wk of either pressure threshold IMT [30 breaths twice daily at ~50% of maximum inspiratory pressure (MIP)] or sham treatment (60 breaths once daily at ~15% of MIP). The subjects completed moderate-, severe- and maximal-intensity "step" exercise transitions on a cycle ergometer before (Pre) and after (Post) the 4-wk intervention period for determination of VO2 kinetics and exercise tolerance. There were no significant changes in the physiological variables of interest after Sham. After IMT, baseline MIP was significantly increased (Pre vs. Post: 155 ± 22 vs. 181 ± 21 cmH2O; P < 0.001), and the degree of inspiratory muscle fatigue was reduced after severe- and maximal-intensity exercise. During severe exercise, the VO2 slow component was reduced (Pre vs. Post: 0.60 ± 0.20 vs. 0.53 ± 0.24 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 765 ± 249 vs. 1,061 ± 304 s; P < 0.01). Similarly, during maximal exercise, the VO2 slow component was reduced (Pre vs. Post: 0.28 ± 0.14 vs. 0.18 ± 0.07 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 177 ± 24 vs. 208 ± 37 s; P < 0.01). Four weeks of IMT, which reduced inspiratory muscle fatigue, resulted in a reduced VO2 slow-component amplitude and an improved exercise tolerance during severe- and maximal-intensity exercise. The results indicate that the enhanced exercise tolerance observed after IMT might be related, at least in part, to improved VO2 dynamics, presumably as a consequence of increased blood flow to the exercising limbs

Short, frequent high-intensity physical activity breaks reduce appetite compared to a continuous moderate-intensity exercise bout

Supplementary materials: This is linked to the online version of the paper at https://doi.org/10.1530/ EC-22-0259.Copyright © 2022 The authors. A single exercise session can affect appetite-regulating hormones and suppress appetite. The effects of short, regular physical activity breaks across the day on appetite are unclear. This study investigated the effects of breaking up sitting with high-intensity physical activity vs a single bout of moderate-intensity exercise and prolonged sitting on appetite control. In this randomised crossover trial, 14 sedentary, inactive adults (7 women) completed 3, 8-h experimental conditions: (i) prolonged sitting (SIT); (ii) 30 min of moderate-intensity exercise followed by prolonged sitting (EX-SIT), and (iii) sitting with 2 min 32 s of high-intensity physical activity every hour (SIT-ACT). Physical activity energy expenditure was matched between EX-SIT and SIT-ACT. Subjective appetite was measured every 30 min with acylated ghrelin and total peptide-YY (PYY) measured hourly in response to two standardised test meals. An ad libitum buffet meal was provided at the end of each condition. Based on linear mixed model analysis, total area under the curve for satisfaction was 16% higher (P = 0.021) and overall appetite was 11% lower during SIT-ACT vs EX-SIT (P = 0.018), with no differences between SIT-ACT and SIT. Time series analysis indicated that SIT-ACT reduced subjective appetite during the majority of the post-lunch period compared with SIT and EX-SIT, with some of these effects reversed earlier in the afternoon (P < 0.05). Total PYY and acylated ghrelin did not differ between conditions. Relative energy intake was 760 kJ lower during SIT-ACT vs SIT (P = 0.024). High-intensity physical activity breaks may be effective in acutely suppressing appetite; yet, appetite-regulating hormones may not explain such responses.Society for Endocrinolog

Health behaviour change considerations for weight loss and type 2 diabetes: nutrition, physical activity and sedentary behaviour

Good nutrition, regular physical activity and low levels of sedentary behaviour are important in the prevention, management and treatment of obesity and type 2 diabetes mellitus (T2DM). Self-management requires individuals to have the capability to enact, opportunity to enable and motivation to perform relevant health behaviours. These behaviours, and the bio-psycho-social drivers of them, should be considered when working in the area of T2DM. Copyright © 2020 John Wiley & Sons

Internal insulation and corrosion control of molten chloride thermal energy storage tanks

A chloride-based molten-salt system that uses a ternary blend of MgCl2/KCl/NaCl is investigated to provide higher-temperature thermal energy storage capability than conventional nitrate salt-based systems. Despite their high thermal stability and operating temperature, molten chlorides present several challenges, including the design of internal liners to prevent the corrosion and thermal stress of alloy tank shells. This work discusses issues and potential solutions related to containment of molten chloride salt, specifically the optimization of the hot face refractory materials for use as internal liners. Three down-selected refractory materials were analyzed with respect to permeation of salt through the material as well as chemical stability during high temperature operation. Through the application of X-ray imaging and electron spectroscopy techniques, highly stable secondary surface phases in equilibrium with the molten salt were identified, as well as time-dependent changes in the salt composition itself

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth’s deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure (Cmcm; commonly referred to as the “post-perovskite” structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 (P63/mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 (P21/m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2S3 structure → P63/mmc structure. However, only the perovskite and CaIrO3 structures are stable with respect to dissociation into NaF and MgF2

Workplace Intervention for Reducing Sitting Time in Sedentary Workers: Protocol for a Pilot Study Using the Behavior Change Wheel

Copyright © 2022 Ojo, Bailey, Chater and Hewson. The workplace is a major contributor to excessive sitting in office workers. There are a wide array of adverse effects of high volumes of sitting time, including an increased risk of type 2 diabetes and depression. Active workstations can be used in effective interventions to decrease workplace sitting. However, there are a lack of interventions that have been developed using a systematic process that is informed by participant needs and a framework for identifying the most appropriate content for the intervention. Applying these methods could increase adherence and potential effectiveness of the intervention. Therefore, the purpose of this pilot study is to examine the feasibility, acceptability, and efficacy of a tailored workplace intervention to reduce and break up sitting in office workers that has been developed using the Behavior Change Wheel and the APEASE (Acceptability, Practicability, Effectiveness/cost-effectiveness, Affordability, Safety/side-effects, Equity) criteria. This article reports the protocol for this study that is currently ongoing. Participants will be cluster-randomized (by offices) to control and intervention groups. The evaluation of the intervention includes determining feasibility by assessing participant recruitment, retention and data completion rates. Adherence to the intervention will be assessed based on daily sitting and standing time relative to guidelines provided to participants as part of the intervention. Outcome measures also include productivity measured using Ecological Momentary Assessment, absenteeism, presenteeism, cardiometabolic risk markers, and wellbeing. The findings of this study will inform the effective design and implementation of interventions for reducing and breaking up sitting in office workers

Lower amounts of daily and prolonged sitting do not lower free-living continuously monitored glucose concentrations in overweight and obese adults: a randomised crossover study

Data Availability Statement: The data presented in this study are available on request from the corresponding author.Copyright: © 2021 by the authors. This study compared the short-term continuously monitored glucose responses between higher and lower amounts of prolonged sitting in overweight and obese adults under free-living conditions. In a randomised crossover design, 12 participants (age 48 ± 10 years, body mass index 33.3 ± 5.5 kg/m2) completed two four-day experimental regimens while wearing a continuous glucose monitor, as follows: (1) uninterrupted sitting (participants were instructed to sit for ≥10 h/day and accrue ≥7, 1 h sitting bouts each day), and (2) interrupted sitting (participants were instructed to interrupt sitting every 30 min during ten of their waking hours with 6–10 min of activity accrued in each hour). Linear mixed models compared outcomes between regimens. None of the continuously monitored glucose variables differed between regimens, e.g., 24 h net incremental area under the glucose curve was 5.9 [95% CI: −1.4, 13.1] and 5.6 [95% CI: −1.7, 12.8] mmol/L∙24 h, respectively (p = 0.47). Daily sitting (−58 min/day, p = 0.001) and sitting bouts lasting ≥30 min (−99 min/day, p < 0.001) were significantly lower and stepping time significantly higher (+40 min/day, p < 0.001) in the interrupted sitting than the uninterrupted sitting regimen. In conclusion, lower amounts of daily and prolonged sitting did not improve free-living continuously measured glucose among overweight and obese adults

Breaking up prolonged sitting with moderate-intensity walking improves attention and executive function in Qatari females

Background: Cultural, environmental and logistical factors promote a sedentary lifestyle within Qatar, particularly for females. Sedentary behaviour is acutely associated with poor cognitive function and fatigue, and chronically may be implicated with cognitive decline (i.e. Alzheimer’s disease). Purpose: To examine the effects of breaking up sitting with short-duration frequent walking bouts on cognitive function and fatigue in Qatari females. Method: Eleven sedentary (sitting �7 h/day) females completed three visits; the first being familiarisation. In a cross-over randomised manner, experimental visits two and three were identical, except participants either remained seated for 5-h (SIT) or interrupted their sitting every 30-min with a 3-min moderate-intensity walk (WALK) on a motorised treadmill. The Computerised Mental Performance Assessment System (COMPASS) assessed cognition at baseline (-15-min), and then at 2.5-h and 5-h into the experimental conditions. Specific COMPASS tasks employed were; serial-3 subtractions (2-min), serial-7 subtractions (2-min), simple reaction time (RT; 50 stimuli), rapid visual information processing [RVIP (5-min)], choice reaction time (CRT; 50 stimuli), and Stroop (60 stimuli); and a visual analogue scale for fatigue (VAS-F) was completed at the same time intervals. Results: There was a significant condition effect for CRT (f = 26.7, p = 0.007). On average CRT was 101 s (95% CI = -47 to -156 s) quicker in WALK compared to SIT. There was a significanttime effect for CRT (f = 15.5, p = 0.01). On average CRT was 134 s slower at 5-h compared to baseline (p = 0.006; 95% CI = -64 to -203 s), and 114 s slower at 5-h compared to 2.5-h (p = 0.01; 95% CI = -44 to -183 s). There was a significant interaction effect for RT in the Stroop incongruent task (f = 10.0, p = 0.03). On average RT was 210 s quicker at 2.5-h in WALK compared to SIT (p = 0.01; 95% CI = -76 to -346 s). Conclusion: Breaking up prolonged sitting with moderate-intensity walking offers an ecologically valid intervention to enhance some aspects of cognitive function, whilst not affecting fatigue in sedentary Qatari females. Whilst these findings are promising, the long-term effects of breaking up sitting on cognitive function requires testing before population level recommendations can be made