Background: The most effective way to cope with high blood sugar spikes is to engage in physical activity in temporal proximity to food intake. However, so far, it is unclear as to whether there is an optimal time for physical activity around food intake. Objectives: We aimed to identify the impact of pre- and post-meal exercise on postprandial glucose excursions in humans with and without type 2 diabetes mellitus. Methods: We conducted a systematic review with meta-analysis, PROSPERO registration number: CRD42022324070. We screened MEDLINE/PubMed, Cochrane/CINAHL/EMBASE, and Web of Knowledge until 1 May, 2022. We used the risk of bias rating with the crossover extension of the Cochrane risk of bias assessment tool II. Standardized mean differences (SMDs, Hedges’ g) with 95% confidence intervals (CIs) were calculated as pooled effect estimates of a random-effects meta-analysis. Eligibility criteria included three-armed randomized controlled trials comparing the acute effects of pre- and post-meal exercise to a no-exercise control in humans. Results: Eight randomized controlled trials (crossover trials, high risk of bias) with 30 interventions in 116 participants (47 diagnosed with type 2 diabetes, 69 without type 2 diabetes) were eligible. Exercise after meal ingestion (real food or meal replacement drinks) led to a reduction in postprandial glucose excursions compared with exercise before eating (15 effect sizes; SMD = 0.47 [95% CI 0.23, 0.70]) and an inactive control condition (15 effect sizes; SMD = 0.55 [95% CI 0.34, 0.75]. Pre-meal exercise did not lead to significantly lower postprandial glucose compared to an inactive control (15 effect sizes; SMD = − 0.13 [95% CI − 0.42, 0.17]). The time between meal and exercise (estimate = − 0.0151; standard error = 0.00473; Z = − 3.19; p = 0.001; 95% CI − 0.024, − 0.006) had a moderating influence on postprandial glucose excursions. Conclusions: Exercise, i.e., walking, has a greater acute beneficial impact on postprandial hyperglycemia when undertaken as soon as possible after a meal rather than after a longer interval or before eating. Clinical Trial Registration: The review was pre-registered in the PROSPERO database (CRD42022324070). The date of submission was 07.04.2022, with the registration on 08.05.2022.

Current evidence indicates that acute aerobic exercise might increase domain-specific cognitive performance. However, only a small number of studies deduced the impact on lower and higher cognitive functions systematically or analyzed dose–response relationships and the underlying mechanisms. This study aimed to expose the dose–response relationships by investigating the influence of exercise duration on subjective and objective arousal, cognitive attention and visual recognition memory tasks. Nineteen participants (eight female; 25.69 ± 3.11 years) were included in a randomized, three-armed intervention study in a cross-over design. The participants completed three different interventions consisting of either 15, 30 or 45 min of cycling at 60–70% VO₂max. Arousal and cognitive measurements were taken before and immediately after (<2 min) exercise. All three interventions led to significant but comparable effects on self-perceived arousal, heart rate (HR) and rating of perceived exertion (RPE) (p < 0.05). Analysis of variance (ANOVA) indicated significant effects of exercise duration on visual recognition memory accuracy. Reaction times for higher and lower cognitive tasks did not change after exercise. Fifteen minutes of aerobic exercise was feasible to induce beneficial changes in self-perceived arousal. Processing speed of visual recognition memory and attention remained unaltered. Exercise exceeding fifteen minutes seemed to negatively impact visual recognition memory accuracy.

Background: Protection against airborne infection is currently, due to the COVID-19-associated restrictions, ubiquitously applied during public transport use, work and leisure time. Increased carbon dioxide re-inhalation and breathing resistance may result thereof and, in turn, may negatively impact metabolism and performance. Objectives: To deduce the impact of the surgical mask and filtering face piece type 2 (FFP2) or N95 respirator application on gas exchange (pulse-derived oxygen saturation (SpO₂), carbon dioxide partial pressure (PCO₂), carbon dioxide exhalation (VCO₂) and oxygen uptake (VO₂)), pulmonary function (respiratory rate and ventilation) and physical performance (heart rate HR, peak power output W_peak). Methods: Systematic review with meta-analysis. Literature available in Medline/Pubmed, the Cochrane Library and the Web of Knowledge with the last search on the 6^th of May 2021. Eligibility criteria: Randomised controlled parallel group or crossover trials (RCT), full-text availability, comparison of the acute effects of ≥ 1 intervention (surgical mask or FFP2/N95 application) to a control/comparator condition (i.e. no mask wearing). Participants were required to be healthy humans and > 16 years of age without conditions or illnesses influencing pulmonary function or metabolism. Risk of bias was rated using the crossover extension of the Cochrane risk of bias assessment tool II. Standardised mean differences (SMD, Hedges' g) with 95% confidence intervals (CI) were calculated, overall and for subgroups based on mask and exercise type, as pooled effect size estimators in our random-effects meta-analysis. Results: Of the 1499 records retrieved, 14 RCTs (all crossover trials, high risk of bias) with 25 independent intervention arms (effect sizes per outcome) on 246 participants were included. Masks led to a decrease in SpO₂ during vigorous intensity exercise (6 effect sizes; SMD = − 0.40 [95% CI: − 0.70, − 0.09], mostly attributed to FFP2/N95) and to a SpO₂-increase during rest (5 effect sizes; SMD = 0.34 [95% CI: 0.04, 0.64]); no general effect of mask wearing on SpO₂ occurred (21 effect sizes, SMD = 0.34 [95% CI: 0.04, 0.64]). Wearing a mask led to a general oxygen uptake decrease (5 effect sizes, SMD = − 0.44 [95% CI: − 0.75, − 0.14]), to slower respiratory rates (15 effect sizes, SMD = − 0.25 [95% CI: − 0.44, − 0.06]) and to a decreased ventilation (11 effect sizes, SMD = − 0.43 [95% CI: − 0.74, − 0.12]). Heart rate (25 effect sizes; SMD = 0.05 [95% CI: − 0.09, 0.19]), W_peak (9 effect sizes; SMD = − 0.12 [95% CI: − 0.39, 0.15]), PCO₂ (11 effect sizes; SMD = 0.07 [95% CI: − 0.14, 0.29]) and VCO₂ (4 effect sizes, SMD = − 0.30 [95% CI: − 0.71, 0.10]) were not different to the control, either in total or dependent on mask type or physical activity status. Conclusion: The number of crossover-RCT studies was low and the designs displayed a high risk of bias. The within-mask- and -intensity-homogeneous effects on gas exchange kinetics indicated larger detrimental effects during exhausting physical activities. Pulse-derived oxygen saturation was increased during rest when a mask was applied, whereas wearing a mask during exhausting exercise led to decreased oxygen saturation. Breathing frequency and ventilation adaptations were not related to exercise intensity. FFP2/N95 and, to a lesser extent, surgical mask application negatively impacted the capacity for gas exchange and pulmonary function but not the peak physical performance. Registration: Prospero registration number: CRD42021244634

Background: The effects of blood flow restriction (training) may serve as a model of peripheral artery disease. In both conditions, circulating micro RNAs (miRNAs) are suggested to play a crucial role during exercise-induced arteriogenesis. We aimed to determine whether the profile of circulating miRNAs is altered after acute resistance training during blood flow restriction (BFR) as compared with unrestricted low- and high-volume training, and we hypothesized that miRNA that are relevant for arteriogenesis are affected after resistance training. Methods: Eighteen healthy volunteers (aged 25 ± 2 years) were enrolled in this three-arm, randomized-balanced crossover study. The arms were single bouts of leg flexion/extension resistance training at (1) 70% of the individual single-repetition maximum (1RM), (2) at 30% of the 1RM, and (3) at 30% of the 1RM with BFR (artificially applied by a cuff at 300 mm Hg). Before the first exercise intervention, the individual 1RM (N) and the blood flow velocity (m/s) used to validate the BFR application were determined. During each training intervention, load-associated outcomes (fatigue, heart rate, and exhaustion) were monitored. Acute effects (circulating miRNAs, lactate) were determined using pre-and post-intervention measurements. Results: All training interventions increased lactate concentration and heart rate (p < 0.001). The high-intensity intervention (HI) resulted in a higher lactate concentration than both lower-intensity training protocols with BFR (LI-BFR) and without (LI) (LI, p = 0.003; 30% LI-BFR, p = 0.008). The level of miR-143-3p was down-regulated by LI-BFR, and miR-139-5p, miR-143-3p, miR-195-5p, miR-197-3p, miR-30a-5p, and miR-10b-5p were up-regulated after HI. The lactate concentration and miR-143-3p expression showed a significant positive linear correlation (p = 0.009, r = 0.52). A partial correlation (intervention partialized) showed a systematic impact of the type of training (LI-BFR vs. HI) on the association (r = 0.35 remaining after partialization of training type). Conclusions: The strong effects of LI-BFR and HI on lactate- and arteriogenesis-associated miRNA-143-3p in young and healthy athletes are consistent with an important role of this particular miRNA in metabolic processes during (here) artificial blood flow restriction. BFR may be able to mimic the occlusion of a larger artery which leads to increased collateral flow, and it may therefore serve as an external stimulus of arteriogenesis.