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INTRODUCTION: A ccessible spaceflight may seem a distant concept. As part of a diverse European Space Agency funded Topical Team, we are working on the physiological feasibility of space missions being undertaken by people with physical disabilities. Here, the first activity of this team is presented in the form of key lessons learned from aviation to inform new work on space missions. DISCUSSION: The first lesson is agreeing on realistic expectations about impairments, their severity, and the possibility of flying independently. This is important in terms of astronaut recruitment and societal expectations. The second lesson relates to training and adjustments for people with disabilities. Flexibility is important while maintaining safety for everyone involved. The third lesson is about managing unconscious bias from the different stakeholders. We conclude by arguing that engagement with people from different backgrounds is essential for the success of the first space mission with people with physical disabilities. [ABSTRACT FROM AUTHOR]

Changes in myonuclear architecture and positioning are associated with exercise adaptations and ageing. However, data on the positioning and number of myonuclei following exercise are inconsistent. Additionally, whether myonuclear domains (MNDs; i.e., the theoretical volume of cytoplasm within which a myonucleus is responsible for transcribing DNA) and myonuclear positioning are altered with age remains unclear. The aim of this investigation was to investigate relationships between age and activity status and myonuclear domains and positioning. Vastus lateralis muscle biopsies from younger endurance‐trained (YT) and older endurance‐trained (OT) individuals were compared with age‐matched untrained counterparts (YU and OU; OU samples were acquired during surgical operation). Serial, optical z‐slices were acquired throughout isolated muscle fibres and analysed to give three‐dimensional coordinates for myonuclei and muscle fibre dimensions. The mean cross‐sectional area (CSA) of muscle fibres from OU individuals was 33%–53% smaller compared with the other groups. The number of nuclei relative to fibre CSA was 90% greater in OU compared with YU muscle fibres. Additionally, scaling of MND volume with fibre size was altered in older untrained individuals. The myonuclear arrangement, in contrast, was similar across groups. Fibre CSA and most myonuclear parameters were significantly associated with age in untrained individuals, but not in trained individuals. These data indicate that regular endurance exercise throughout the lifespan might better preserve the size of muscle fibres in older age and maintain the relationship between fibre size and MND volumes. Inactivity, however, might result in reduced muscle fibre size and altered myonuclear parameters. What is the central question of the study?How do endurance exercise and the ageing process affect the positioning and number of myonuclei within muscle fibres?What are the main findings and their importance?There was reduced muscle fibre size, with smaller myonuclear domains and altered myonuclear domain scaling in older, untrained individuals. However, older trained individuals maintained similar muscle and myonuclear characteristics to younger trained individuals. This suggests that inactivity, rather than ageing, influences muscle fibre and myonuclear characteristics. These observations suggest that consistent endurance exercise over one's lifetime might help to preserve muscle fibre size and quality and myonuclear arrangement into old age. [ABSTRACT FROM AUTHOR]

Studies suggest that inducing gut microbiota changes may alter both muscle physiology and cognitive behaviour. Gut microbiota may play a role in both anabolic resistance of older muscle, and cognition. In this placebo controlled double blinded randomised controlled trial of 36 twin pairs (72 individuals), aged ≥60, each twin pair are block randomised to receive either placebo or prebiotic daily for 12 weeks. Resistance exercise and branched chain amino acid (BCAA) supplementation is prescribed to all participants. Outcomes are physical function and cognition. The trial is carried out remotely using video visits, online questionnaires and cognitive testing, and posting of equipment and biological samples. The prebiotic supplement is well tolerated and results in a changed gut microbiome [e.g., increased relative Bifidobacterium abundance]. There is no significant difference between prebiotic and placebo for the primary outcome of chair rise time (β = 0.579; 95% CI -1.080-2.239 p = 0.494). The prebiotic improves cognition (factor score versus placebo (β = -0.482; 95% CI,-0.813, -0.141; p = 0.014)). Our results demonstrate that cheap and readily available gut microbiome interventions may improve cognition in our ageing population. We illustrate the feasibility of remotely delivered trials for older people, which could reduce under-representation of older people in clinical trials. [ABSTRACT FROM AUTHOR]

INTRODUCTION: G tolerance has been widely assessed using Peripheral Light Loss (PLL), but this approach has several limitations and may lack sensitivity. The aim of this study was to investigate the use of a foveal visual endpoint for centrifuge research (Grating Loss; GL) and assess its repeatability, reliability, and usability with PLL as a reference. METHODS: A total of 11 subjects undertook centrifuge assessment. Gradual onset sessions (GOR; 0.1G · s−1) measured both endpoints simultaneously and were performed twice, consisting of six determinations with anti-G suits activated (GOR-On) and six without (GOR-Off). Four determinations of each endpoint were also taken during rapid onset runs (ROR; 3G · s−1). Usability was scored subjectively. RESULTS: The GL endpoint was reached 0.3–0.5 Gz lower than PLL with each endpoint correlating strongly in GOR-Off (r = 0.93), GOR-On (r = 0.95), and ROR (r = 0.86). The GL had excellent test–retest repeatability (intraclass correlation coefficient: GOR-Off/On = 0.99, ROR = 0.92) and low within-subject variability. Between-subject variance equaled PLL in all conditions. Subjective usability endpoint ratings were equal for all conditions. DISCUSSION: For the 11 individuals tested, the GL was a reliable, repeatable, and usable endpoint, with similar performance to PLL. GL may prove useful as a supplementary endpoint for human centrifuge research as a secondary data point or to reduce fatigue in repeated measurements. The foveal GL stimulus was lost before PLL, contrary to popular models of visual changes under +Gz. [ABSTRACT FROM AUTHOR]

Specific force (SF) has been shown to be reduced in some but not all studies of human aging using chemically skinned single muscle fibers. This may be due, in part, not only to the health status/physical activity levels of different older cohorts, but also from methodological differences in studying skinned fibers. The aim of the present study was to compare SF in fibers from older hip fracture patients (HFP), healthy master cyclists (MC), and healthy nontrained young adults (YA) using two different activating solutions. Quadriceps muscle samples and 316 fibers were obtained from HFPs (74.6 ± 4 years, n = 5), MCs (74.8 ± 1, n = 5), and YA (25.5 ± 2, n = 6). Fibers were activated (pCa 4.5, 15°C) in solutions containing either 60 mM N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid pH buffer (TES) or 20 mM imidazole. SF was determined by normalizing force to fiber cross-sectional area (CSA) assuming either an elliptical or circular shape and to fiber myosin heavy chain content. Activation in TES resulted in significantly higher MHC-I SF in all groups and YA MHC-IIA fibers, irrespective of normalization method. Although there were no differences in SF between the participant groups, the ratio of SF between the TES and imidazole solutions was lower in HFPs compared with YAs (MHC-I P < 0.05; MHC-IIA P = 0.055). Activating solution composition, as opposed to donor characteristics, had a more notable effect on single fiber SF. However, this two-solution approach revealed an age-related difference in sensitivity in HFPs, which was not shown in MCs. This suggests further novel approaches may be required to probe age/activity-related differences in muscle contractile quality. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Military rotary-wing operations require sustained levels of cognitive and psychomotor performance from aircrew to ensure safety and operational effectiveness. Significant flight-related neck pain (SFRNP) is common amongst rotary-wing aircrew, potentially affecting their performance. This study aimed to examine the effect of SFRNP on psychomotor and cognitive performance in a cohort of military rotarywing aircrew in the operational flight environment. METHODOLOGY: A field study was conducted using a dual-task paradigm with 40 military operational CH-47 rear crew (39 male, 1 female). The primary outcome variable was the Dual Task Effect (DTE) (% change between single and dual task conditions) for cognitive and psychomotor performance on a novel simulated flight-task test battery. These data were stratified post-hoc for those with or without SFRNP. This study received favourable opinion from the UK Ministry of Defence Research Ethics Committee (MODREC). RESULTS: 65% (n=26) of participants reported SFRNP during the test flights. Mean intensity of SFRNP was 2.5 on the Numerical Pain Rating Scale. Pre-flight, there was a significantly greater deterioration in psychomotor performance under dual task conditions for the SFRNP group (DTE -15.8), compared to the non-neck pain group (DTE 1.5) (p=.01). Deterioration in dual-task performance (DTE) for both the cognitive and psychomotor conditions was slightly worse following the operational flight sortie; however, no significant differences were observed after the operational flight sortie in either the SFRNP or non-neck pain group (p=>.05). DISCUSSION: SFRNP was found to be present amongst this sample of military rotary-wing aircrew. There was a detectable change in the cognitive and psychomotor performance of the aircrew using the dual-task paradigm. Whilst there was evidence that SFRNP was associated with reduced psychomotor dual-task performance, operational flight exposure did not affect aircrew performance in this study. Future research could consider the relationship between the pain intensity and its effect on performance. Learning Objectives 1. Psychomotor dual-task performance was reduced in military rotarywing rear crew with significant flight-related neck pain. 2. Operational flight exposure was not associated with reduced dual-task performance in aircrew with or without significant flight-related neck pain in this study. [ABSTRACT FROM AUTHOR]

The author reflects on being editor in chief of the journal on the last 12 years and the last issue with him as editor. He talks about the establishment of the journal in 1991 with the late Professor Bengt Saltin as its first editor in chief, his reflection on the comment of his friend on becoming editor in chief of the journal, and his successor as editor in chief of the journal.

Creatine dilution (D3‐cr) is a technique for estimating total skeletal muscle mass (SMM) with practical utility, but has not been applied in athletic populations where body composition may differ to that in the normal population. This study aimed to assess the agreement between SMM derived from both D3‐cr and that obtained from whole‐body magnetic resonance imaging (MRI) in 15 male and 5 female national level kayakers (stature: 182.0 ± 13.1 and 170.0 ± 9.0 cm; body mass: 80.6 ± 9.9 and 66.4 ± 6.0 kg; V̇O2peak: 56.5 ± 7.0 and 49.6 ± 4.4 mL kg−1 min−1, mean ± SD). SMM was determined following 60 mg of dosed D3‐cr and analysis of expelled urine collected on four subsequent days for creatine, creatinine, D3‐cr, and D3‐creatinine using liquid chromatography/mass spectroscopy. SMM was then estimated by assuming a creatine pool size of 4.3 g/kg. During the same time period, a whole‐body MRI was undertaken to derive SMM from the analysis of multiple slices taken across the body. A strong positive correlation (F = 74.32; R = 0.90; P <.0001) between the two methods was observed, but the D3‐cr SMM was found to be significantly higher (43.3 ± 6.8 kg) when compared with MRI (36.3 ± 5.8 kg, P <.0001). However, the difference between the methods was removed when a higher intramuscular creatine pool (5.1 g/kg) was assumed. These data show that D3‐cr has potential utility in athletes, as referenced against MRI, but show that assumptions regarding creatine pool size need to be carefully considered. [ABSTRACT FROM AUTHOR]

This brief review focuses on the relationships and interactions between human ageing, exercise and physiological function. It explores the importance of the selection of participants for ageing research, the strengths and deficiencies of both cross‐sectional and longitudinal studies, and the complexities involved in understanding time‐dependent, lifelong physiological processes. As being physically active is crucial to fostering healthy ageing, it is essential that participants in health and ageing research are defined in terms of their physical activity/exercise status as well as other lifestyle factors. Comparisons of exercisers with non‐exercisers has suggested that there is a mosaic of regulation of ageing both within and across physiological systems. We suggest that four broad categories exist which encompass this regulation. These are (i) systems and indices that are age dependent, but activity independent; (ii) systems that are age dependent, but also malleable by exercise; (iii) systems that are not age affected but are altered by exercise; and (iv) systems that are neither age nor activity dependent. We briefly explore the concept of a mosaic of regulation in a selection of physiological systems. These include skeletal muscle, the immune and endocrine systems, gastrointestinal as well as cognitive function. We go onto examine how these categories might fit within the broad framework of understanding the physiology of human ageing. Schematic depiction of how healthy or diseased ageing phenotypes are the product of the interaction and regulation of physiological systems that can broadly be grouped into four categories on the basis of their malleability or otherwise to exercise and to the ageing process. [ABSTRACT FROM AUTHOR]