Cross-adaptation from heat stress to hypoxia: A systematic review and exploratory meta-analysis.

Cross-adaptation (CA) refers to the successful induction of physiological adaptation under one environmental stressor (e.g., heat), to enable subsequent benefit in another (e.g., hypoxia). This systematic review and exploratory meta-analysis investigated the effect of heat acclimation (HA) on physiological, perceptual and physical performance outcome measures during rest, and submaximal and maximal intensity exercise in hypoxia. Database searches in Scopus and MEDLINE were performed. Studies were included when they met the Population, Intervention, Comparison, and Outcome criteria, were of English-language, peer-reviewed, full-text original articles, using human participants. Risk of bias and study quality were assessed using the COnsensus based Standards for the selection of health status Measurement INstruments checklist. Nine studies were included, totalling 79 participants (100 % recreationally trained males). The most common method of HA included fixed-intensity exercise comprising 9 ± 3 sessions, 89 ± 24-min in duration and occurred within 39 ± 2 °C and 32 ± 13 % relative humidity. CA induced a moderate, beneficial effect on physiological measures at rest (oxygen saturation: g = 0.60) and during submaximal exercise (heart rate: g = -0.65, core temperature: g = -0.68 and skin temperature: g = -0.72). A small effect was found for ventilation (g = 0.24) and performance measures (peak power: g = 0.32 and time trial time: g = -0.43) during maximal intensity exercise. No effect was observed for perceptual outcome measures. CA may be appropriate for individuals, such as occupational or military workers, whose access to altitude exposure prior to undertaking submaximal activity in hypoxic conditions is restricted. Methodological variances exist within the current literature, and females and well-trained individuals have yet to be investigated. Future research should focus on these cohorts and explore the mechanistic underpinnings of CA.

Four-year longitudinal associations of physical activity, waist circumference, and blood pressure in UK adolescents.

BACKGROUND: This study assessed the specific influence of physical activity (PA) and waist circumference (WC) on the 4-year growth trajectory of blood pressure in UK high-school students. METHODS: Four-year longitudinal monitoring of 1501 adolescents was conducted as part of the EoEHHS. Measurements were taken in Grades (G)7, 9, and 11. RESULTS: Systolic (SBP) and diastolic blood pressure (DBP) increased over the 4-year period (SBP G7 114.6 ± 8.9 mmHg, G9 118.1 ± 9.7 mmHg, G11 122.8 ± 7.8 mmHg; DBP G7 66.7 ± 6.6 mmHg, G9 68.0 ± 6.4 mmHg, G11 70.0 ± 5.2 mmHg). Baseline WC predicted baseline and growth in SBP, but the strongest contribution to SBP came from changes in WC (ß = 0.084, p = 0.002). Baseline PAQ-A score (ß = -0.822, p = 0.020) and changes in PAQ-A score (ß = -0.650, p = 0.019) were associated with smaller increases in DBP over the 4-year measurement period. CONCLUSIONS: Baseline and change in WC predicted the growth trajectory of SBP, while baseline and change in PA predicted the growth trajectory of DBP. PA and WC have a prognostic value in predicting changes in blood pressure in adolescents. Increasing PA during adolescence could slow the rise in DBP over time. This is meaningful for future hypertension and CVD risk reduction into adulthood. IMPACT: Hypertension in adolescents is a growing health problem that is often overlooked. Baseline and changes in waist circumference over a 4-year period predicted development of systolic blood pressure, while baseline and changes in physical activity predicted development of diastolic blood pressure. Physical activity and waist circumference have a prognostic value in predicting changes in blood pressure in adolescents and could be valuable in planning programmes to prevent hypertension in similar communities and reduce the risk of future adult hypertension.

Responsiveness to endurance training can be partly explained by the number of favorable single nucleotide polymorphisms an individual possesses.

Cardiorespiratory fitness is a key component of health-related fitness. It is a necessary focus of improvement, especially for those that have poor fitness and are classed as untrained. However, much research has shown individuals respond differentially to identical training programs, suggesting the involvement of a genetic component in individual exercise responses. Previous research has focused predominantly on a relatively low number of candidate genes and their overall influence on exercise responsiveness. However, examination of gene-specific alleles may provide a greater level of understanding. Accordingly, this study aimed to investigate the associations between cardiorespiratory fitness and an individual's genotype following a field-based endurance program within a previously untrained population. Participants (age: 29 ± 7 years, height: 175 ± 9 cm, mass: 79 ± 21 kg, body mass index: 26 ± 7 kg/m2) were randomly assigned to either a training (n = 21) or control group (n = 24). The training group completed a periodized running program for 8-weeks (duration: 20-30-minutes per session, intensity: 6-7 Borg Category-Ratio-10 scale rating, frequency: 3 sessions per week). Both groups completed a Cooper 12-minute run test to estimate cardiorespiratory fitness at baseline, mid-study, and post-study. One thousand single nucleotide polymorphisms (SNPs) were assessed via saliva sample collections. Cooper run distance showed a significant improvement (0.23 ± 0.17 km [11.51 ± 9.09%], p < 0.001, ES = 0.48 [95%CI: 0.16-0.32]), following the 8-week program, whilst controls displayed no significant changes (0.03 ± 0.15 km [1.55 ± 6.98%], p = 0.346, ES = 0.08, [95%CI: -0.35-0.95]). A significant portion of the inter-individual variation in Cooper scores could be explained by the number of positive alleles a participant possessed (r = 0.92, R2 = 0.85, p < 0.001). These findings demonstrate the relative influence of key allele variants on an individual's responsiveness to endurance training.

Correction to: COVID-19: self-reported reductions in physical activity and increases in sedentary behaviour during the first national lockdown in the United Kingdom.

[This corrects the article DOI: 10.1007/s11332-022-01012-0.].

COVID-19: self-reported reductions in physical activity and increases in sedentary behaviour during the first national lockdown in the United Kingdom.

Purpose: The United Kingdom (UK) government imposed its first national lockdown in response to COVID-19 on the 23rd of March 2020. Physical activity and sedentary behaviour levels are likely to have changed during this period. Methods: An online survey was completed by n = 266 adults living within the UK. Differences in day-to-day and recreational physical activity (at moderate and vigorous intensities), travel via foot/cycle, and sedentary behaviour were compared before and during the initial COVID-19 lockdown. Results: The median level of total weekly physical activity significantly reduced (- 15%, p < 0.001) and daily sedentary time significantly increased (+ 33%, p < 0.001). The former was caused by a significant reduction in weekly day-to-day physical activity at moderate intensities (p < 0.001), recreational activities at vigorous (p = 0.016) and moderate (p = 0.030) intensities, and travel by foot/cycle (p = 0.031). Sub-group analyses revealed that some populations became disproportionally more physically inactive and/or sedentary than others, such as those that were: living in a city (versus village), single (versus a relationship), an athlete (versus non-athlete), or earning an average household income < £25,000 (versus > £25,000). Conclusions: Now that the UK is transitioning to a state of normal living, strategies that can help individuals gradually return to physical activities, in accordance with the 2020 WHO guidelines, are of paramount importance to reducing risks to health associated with physical inactivity and sedentary behaviour.

Do exercise-associated genes explain phenotypic variance in the three components of fitness? a systematic review & meta-analysis.

The aim of this systematic review and meta-analysis was to identify a list of common, candidate genes associated with the three components of fitness, specifically cardiovascular fitness, muscular strength, and anaerobic power, and how these genes are associated with exercise response phenotype variability, in previously untrained participants. A total of 3,969 potentially relevant papers were identified and processed for inclusion. After eligibility and study selection assessment, 24 studies were selected for meta-analysis, comprising a total of 3,012 participants (male n = 1,512; females n = 1,239; not stated n = 261; age 28 ± 9 years). Meta-Essentials spreadsheet 1.4 (Microsoft Excel) was used in creating the forest plots and meta-analysis. IBM SPSS statistics V24 was implemented for the statistical analyses and the alpha was set at p ≤ 0.05. 13 candidate genes and their associated alleles were identified, which were associated with the phenotypes of interest. Analysis of training group data showed significant differential phenotypic responses. Subgroup analysis showed; 44%, 72% and 10% of the response variance in aerobic, strength and power phenotypes, respectively, were explained by genetic influences. This analysis established that genetic variability explained a significant proportion of the adaptation differences across the three components of fitness in the participants post-training. The results also showed the importance of analysing and reporting specific gene alleles. Information obtained from these findings has the potential to inform and influence future exercise-related genes and training studies.

Does Protein Supplementation Support Adaptations to Arduous Concurrent Exercise Training? A Systematic Review and Meta-Analysis with Military Based Applications.

We evaluated the impact of protein supplementation on adaptations to arduous concurrent training in healthy adults with potential applications to individuals undergoing military training. Peer-reviewed papers published in English meeting the population, intervention, comparison and outcome criteria were included. Database searches were completed in PubMed, Web of science and SPORTDiscus. Study quality was evaluated using the COnsensus based standards for the selection of health status measurement instruments checklist. Of 11 studies included, nine focused on performance, six on body composition and four on muscle recovery. Cohen's d effect sizes showed that protein supplementation improved performance outcomes in response to concurrent training (ES = 0.89, 95% CI = 0.08-1.70). When analysed separately, improvements in muscle strength (SMD = +4.92 kg, 95% CI = -2.70-12.54 kg) were found, but not in aerobic endurance. Gains in fat-free mass (SMD = +0.75 kg, 95% CI = 0.44-1.06 kg) and reductions in fat-mass (SMD = -0.99, 95% CI = -1.43-0.23 kg) were greater with protein supplementation. Most studies did not report protein turnover, nitrogen balance and/or total daily protein intake. Therefore, further research is warranted. However, our findings infer that protein supplementation may support lean-mass accretion and strength gains during arduous concurrent training in physical active populations, including military recruits.

Derivation, propagation, and characterization of neuroprogenitors from pluripotent stem cells (hESCs and hiPSCs).

The differentiation of human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) towards functional neurons particularly hold great potential for the cell-based replacement therapy in neurodegenerative diseases. Here, we describe a stepwise differentiation protocol that mimics the early stage of neural development in human to promote the generation of neuroprogenitors at a high yield. Both the hESCs and hiPSCs are initially cultured in an optimized feeder-free condition, which offer an efficient formation of aggregates. To specify the neuroectodermal specification, these aggregates are differentiated in a defined neural induction medium to develop into neural rosettes-like structures. The rosettes are expanded into free-floating sphere and can be further propagated or developed into variety of neuronal subtypes.

Human induced pluripotent stem cells derived under feeder-free conditions display unique cell cycle and DNA replication gene profiles.

Use of animal feeder layers and serum containing media in the derivation and propagation of induced pluripotent stem cells (iPSCs) can hinder clinical translation, because of the presence of xeno-material/pathogens. A defined and standardized system would be ideal for generating a homogenous population of iPSCs, which closely resembles human embryonic stem cells (hESCs). This article presents a novel and extensive comparison between in-house produced iPSCs and hESCs under "feeder" and "feeder-free" conditions, using transcriptomic genome-wide microarray analysis. We generated a list of pluripotency-associated and bivalent domain-containing genes by meta-analysis to measure qualitatively the degree of reprogramming in feeder-free derived iPSCs, in which both profiles displayed similar levels of gene expression as in hESCs. Gene ontology analysis showed that feeder-free iPSCs have enriched terms belonging to DNA repair/replication and cell cycle, which are signature to pluripotent cells. Transcriptomic data combined with directed differentiation assays, indicated that variability among iPSC lines is minimized when using a feeder-free cultural system, which may serve as a platform for further developing regenerative medicine compliant human iPSCs.