Beyond the Clinic: Maximum Free-Living Stepping as a Potential Measure of Physical Performance

Measures of physical performance captured within a clinical setting are commonly used as a surrogate for underlying health or disease risk within an individual. By measuring physical behaviour within a free-living setting, we may be able to better quantify physical performance. In our study, we outline an approach to measure maximum free-living step count using a body-worn sensor as an indicator of physical performance. We then use this approach to characterise the maximum step count over a range of window durations within a population of older adults to identify a preferred duration over which to measure the maximum step count. We found that while almost all individuals (97%) undertook at least one instance of continuous stepping longer than two minutes, a sizeable minority of individuals (31%) had no periods of continuous stepping longer than six minutes. We suggest that the maximum step count measured over a six-minute period may be too sensitive to the adults' lack of opportunity to undertake prolonged periods of stepping, and a two-minute window could provide a more representative measure of physical performance

Linear plasma experiment for non-linear microwave interaction experiments

As a non-linear medium, plasma can exhibit diverse dynamics when excited bymultiple EM waves. Electromagnetic waves are vital to the introduction of energyin laser plasma interactions and the heating of magnetically confined fusion reactors.In laser plasma applications Raman coupling via a Langmuir oscillation or Brillouinscattering mediated by ion-acoustic waves are of interest. Signals with normalisedintensities approaching those used in some recent laser plasma interactions can begenerated using powerful and flexible microwave amplifiers, interacting in relativelytenuous, cool and accessible plasma. Other multi-wave interactions are interesting formagnetic confinement fusion plasmas, for example beat-wave interactions betweentwo microwave signals coupling to cyclotron motion of the ions and electrons or thelower hybrid oscillations may be useful in heating the plasmas or for driving currents.A linear plasma experiment is being built to test such multifrequency microwaveinteraction in plasma, based on prior research on geophysical cyclotron wave emissionand propagation [1,2]. The main section of the plasma will be magnetised at up to0.05T, with the plasma created by an RF helicon source to generate a dense, large,cool plasma with a high ionisation fraction. A range of frequency-flexible sources willprovide microwave beams to enable multi-wave coupling experiments. The paper willpresent progress on this apparatus and experiments.The authors gratefully acknowledge support from the EPSRC, MBDA UK Ltd andTMD Technologies Ltd.[1] Ronald K., Speirs D.C., McConville S.L., Phelps A.D.R., Robertson C.W., WhyteC.G., He W., Gillespie K.M., Cross A.W., Bingham R., 2008, Phys. Plasmas, 15,art.056503[2] Speirs, D.C., Bingham, R., Cairns, R.A., Vorgul, I., Kellett, B.J., Phelps, A.D.R.,Ronald, K, 2014, Phys. Rev. Lett., 113, art 15500

Obesity and male breast cancer: Provocative parallels?

While rare compared to female breast cancer the incidence of male breast cancer (MBC) has increased in the last few decades. Without comprehensive epidemiological studies, the explanation for the increased incidence of MBC can only be speculated. Nevertheless, one of the most worrying global public health issues is the exponential rise in the number of overweight and obese people, especially in the developed world. Although obesity is not considered an established risk factor for MBC, studies have shown increased incidence among obese individuals. With this observation in mind, this article highlights the correlation between the increased incidence of MBC and the current trends in obesity as a growing problem in the 21st century, including how this may impact treatment. With MBC becoming more prominent we put forward the notion that, not only is obesity a risk factor for MBC, but that increasing obesity trends are a contributing factor to its increased incidence

Periprandial changes of the sympathetic–parasympathetic balance related to perceived satiety in humans

Food intake regulation involves various central and peripheral mechanisms. In this study the relevance of physiological responses reflecting the autonomic nervous system were evaluated in relation to perceived satiety. Subjects were exposed to a lunch-induced hunger-satiety shift, while profiling diverse sensory, physiological, and biochemical characteristics at 15 min intervals. Sensory ratings comprised questionnaires with visual analogues scales about their feeling of satiety, desire to eat, fullness, and hunger. Physiological characteristics included heart rate, heart rate variability, and blood pressure, while biochemical markers such as cortisol levels and α-amylase activity were monitored in saliva. The four sensory ratings correlated with heart rate and salivary α-amylase suggesting a higher sympathetic tone during satiety. Furthermore, heart rate variability was associated with age and waist-to-hip ratio and cortisol levels negatively correlated with body mass index. Finally, neither chewing nor swallowing contributed to a heart rate increase at food consumption, but orosensory stimulation, as tested with modified sham feeding, caused a partial increase of heart rate. In conclusion, after meal ingestion critical physiological alterations reveal a elevated sympathetic tone, which is a potential measure of satiety

Estimating changes in physical behaviour during lockdowns using accelerometry_based simulations in a large UK cohort

To contain the recent COVID-19 outbreak restrictions have been imposed, which has limited outdoor activity. These physical behaviour changes can have serious health implications, but there is little objective information quantifying these changes. This study aimed to estimate the change in physical behaviour levels during full lockdown conditions using objective data collected from a thigh-worn activity monitor. Data used was from 6,492 individuals in the 1970 British Cohort Study, collected between 2016 and 2018. Using walking bout characteristics, days were classified as either "indoor only" (n=861), "indoor and exercise" (n=167) and "outdoor active" (n=31,934). When compared to "outdoor active" days, "indoor only" days had 6,590 fewer steps per day (2,320 vs 8,876, p < 0.001), a longer sedentary time (1.5 hours, p < 0.001), longer lying time (1.4 hours, p < 0.001) and shorter standing (1.9 hours, p < 0.001) and stepping (1.3 hours, p < 0.001) times. The "indoor and exercise" days had a smaller number of steps compared to "outdoor active" (7,932 vs 8,876, p < 0.05). There is a strong relationship between reduced daily stepping, and increased sedentary time, with a range of poor health outcomes. This has important implications for public health policy and messaging during pandemics

Use of accelerometers to track changes in stepping behavior with the introduction of the 2020 COVID pandemic restrictions: a case study

The COVID-19 lockdown introduced restrictions to free-living activities. Changes to these activities can be accurately quantified using combined measurement. Using activPAL3 and self-reports to collect activity data, the study aimed to quantify changes that occurred in physical activity and sedentary behavior between prelockdown and lockdown. The study also sought to determine changes in indoor and outdoor stepping. Methods: Using activPAL3, four participants recorded physical activity data prelockdown and during lockdown restrictions (February–June 2020). Single events (sitting, standing, stepping, lying) were recorded and analyzed by the CREA algorithm using an event-based approach. The analysis focused on step count, sedentary time, and lying (in bed) time; median and interquartile range were calculated. Daily steps classified as taking place indoors and outdoors were calculated separately. Results: 33 prelockdown and 92 in-lockdown days of valid data were captured. Median daily step count across all participants reduced by 14.8% (from 5,828 prelockdown to 4,963 in-lockdown), while sedentary and lying time increased by 4% and 8%, respectively (sedentary: 9.98–10.30 hr; lying: 9.33–10.05 hr). Individual variations were observed in hours spent sedentary (001: 8.44–8.66, 002: 7.41–8.66, 003: 11.97–10.59, 004: 6.29–7.94, and lying (001: 9.69–9.49, 002: 11.46–11.66, 003: 7.63–9.34, 004: 9.7–11.12) pre- and in-lockdown. Discrepancies in self-report versus algorithm classification of indoor/outdoor stepping were observed for three participants. Conclusion: The study quantitively showed lockdown restrictions negatively impacted physical activity and sedentary behavior; two variables closely linked to health outcomes. This has important implications for public health policies to help develop targeted interventions and mandates that encourage additional physical activity and lower sedentary behavior

Characterization of a Penning discharge for investigation of auroral radio wave generation mechanisms

Auroral Kilometric Radiation (AKR), observed by satellites in the Earth’s magnetosphere, is naturally generated in regions of partial plasma depletion (auroral density cavity) in the polar magnetosphere at approximately 3200 km altitude. As an electron descends through these regions of partial plasma depletion along magnetic field lines towards the Earth’s ionosphere, the field lines increases and, through conservation of the magnetic moment, the electron gives up axial velocity in favour of perpendicular velocity. This results in a horseshoe-shaped distribution function in parallel/perpendicular-velocity space which is unstable to X-mode radiation, near the cyclotron frequency. Power levels as high as GW levels have been recorded with frequencies around 300 kHz. The background plasma frequency within the auroral density cavity is approximately 9 kHz corresponding to a plasma density 1cm−3. A laboratory experiment scaled from auroral frequency to microwave frequency has previously been reported. Here, the addition of a Penning trap to simulate the background plasma of the density cavity is reported, with measurements ne∼2×1014–2.17×1015 m−3, fpe ∼128–418MHz and fce ∼5.21GHz giving a ratio of ωce/ωpe comparable to the magnetospheric AKR source region

Microwave generation from an electron horseshoe distribution: theory and experiment

When a beam of electrons encounters an increasing magnetic field along its vector of motion, conservation of the magnetic moment results in the formation of a crescent or horseshoe-shaped velocity distribution. A scenario analogous to this occurs in the terrestrial auroral zone where particles are accelerated into the polar regions of the earth's magnetic dipole and expand adiabatically in velocity space. The resultant horseshoe-shaped velocity distribution has been shown to be unstable to a cyclotron-maser type instability [1-3]. This instability has been postulated as the mechanism responsible for auroral kilometric radiation and also nonthermal radiation from other astrophysical bodies [4]. In this paper we describe both theory, simulations and a laboratory experiment to investigate the generation of microwave radiation when an electron beam is magnetically compressed by a factor of 35