The efficacy of a home-use metabolic device (Lumen) in response to a short-term low and high carbohydrate diet in healthy volunteers.

BACKGROUND: Based on stoichiometric assumptions, and real-time assessment of expired carbon dioxide (%CO2) and flow rate, the Lumen device provides potential for consumers/athletes to monitor metabolic responses to dietary programs outside of laboratory conditions. However, there is a paucity of research exploring device efficacy. This study aimed to evaluate Lumen device response to: i) a high-carbohydrate meal under laboratory conditions, and ii) a short-term low- or high-carbohydrate diet in healthy volunteers. METHODS: Following institutional ethical approval, 12 healthy volunteers (age: 36 ± 4 yrs; body mass: 72.1 ± 3.6 kg; height: 1.71 ± 0.02 m) performed Lumen breath and Douglas bag expired air measures under fasted laboratory conditions and at 30 and 60 min after a high-carbohydrate (2 g·kg-1) meal, along with capilliarized blood glucose assessment. Data were analyzed using a one-way ANOVA, with ordinary least squares regression used to assess the model between Lumen expired carbon dioxide percentage (L%CO2) and respiratory exchange ratio (RER). In a separate phase, 27 recreationally active adults (age: 42 ± 2 yrs; body mass: 71.9 ± 1.9 kg; height: 1.72 ± 0.02 m) completed a 7-day low- (~20% of energy intake [EI]; LOW) or high-carbohydrate diet (~60% of EI; HIGH) in a randomized, cross-over design under free-living conditions. L%CO2 and derived Lumen Index (LI) were recorded daily across morning (fasted and post-breakfast) and evening (pre/post meal, pre-bed) periods. Repeated measures ANOVA were employed for main analyses, with Bonferroni post-hoc assessment applied (P ≤ 0.05). RESULTS: Following the carbohydrate test-meal, L%CO2 increased from 4.49 ± 0.05% to 4.80 ± 0.06% by 30 min, remaining elevated at 4.76 ± 0.06% by 60 min post-feeding (P < 0.001, ηp2 = 0.74). Similarly, RER increased by 18.1% from 0.77 ± 0.03 to 0.91 ± 0.02 by 30 min post-meal (P = 0.002). When considering peak data, regression analysis demonstrated a significant model effect between RER and L%CO2 (F = 5.62, P = 0.03, R2 = 0.20). Following main dietary interventions, no significant interactions (diet × day) were found. However, main diet effects were evident across all time-points assessed, highlighting significant differences for both L%CO2 and LI between LOW and HIGH conditions (P < 0.003). For L%CO2, this was particularly noted under fasted (4.35 ± 0.07 vs. 4.46 ± 0.06%, P = 0.001), pre-evening meal (4.35 ± 0.07 vs. 4.50 ± 0.06%, P < 0.001), and pre-bed time-points (4.51 ± 0.08 vs. 4.61 ± 0.06%, P = 0.005). CONCLUSION: Our findings demonstrated that a portable, home-use metabolic device (Lumen) detected significantly increased expired %CO2 in response to a high-carbohydrate meal, and may be useful in tracking mean weekly changes to acute dietary carbohydrate modifications. Additional research is warranted to further determine the practical and clinical efficacy of the Lumen device in applied compared to laboratory settings.

COVID-19 patients require multi-disciplinary rehabilitation approaches to address persisting symptom profiles and restore pre-COVID quality of life.

BACKGROUND: Long-COVID diagnosis is prominent, and our attention must support those experiencing debilitating and long-standing symptoms. To establish patient pathways, we must consider the societal and economic impacts of sustained COVID-19. Accordingly, we sought to determine the pertinent areas impacting quality of life (QoL) following a COVID-19 infection. RESEARCH METHODS: Three hundred and eighty-one participants completed a web-based survey (83% female, 17% male) consisting of 70 questions across 7 sections (demographics, COVID-19 symptoms; QoL; sleep quality; breathlessness; physical activity and mental health). Mean age, height, body mass and body mass index (BMI) were 42 ± 12 years, 167.6 ± 10.4 cm, 81.2 ± 22.2 kg, and 29.1 ± 8.4 kg.m2, respectively. RESULTS: Participant health was reduced because of COVID-19 symptoms ('Good health' to 'Poor health' [P < 0.001]). Survey respondents who work reported ongoing issues with performing moderate (83%) and vigorous (79%) work-related activities. CONCLUSIONS: COVID-19 patients report reduced capacity to participate in activities associated with daily life, including employment activities. Bespoke COVID-19 support pathways must consider multi-disciplinary approaches that address the holistic needs of patients to restore pre-pandemic quality of life and address experienced health and wellbeing challenges.Plain Language Summary: The long-term impact of long-COVID has a dramatic impact upon daily activities and lifestyle. The development of bespoke support pathways to support patients must address the physical and psychological considerations to adequately restore pre-COVID quality of life and address broader societal and economic implications, especially for those that are of working age.

Sedentary behaviour and chronic stress in old age: A cross-sectional analysis of TV viewing and hair cortisol concentrations.

PURPOSE: Several studies have reported a positive association between sedentary behaviour and perceived stress, but none using a population-based sample has examined this relationship using an objective measure of stress exposure. The aim of this study was therefore to analyse the association between sedentary behaviour (operationalised as daily TV viewing time) and levels of cortisol in hair (an objective measure of chronic stress) using data from a large population-based sample of older adults. METHOD: Analyses used cross-sectional data from older adults (≥50 years) participating in Wave 6 (2012/13) of the English Longitudinal Study of Ageing. Hair cortisol concentrations were determined from the scalp-nearest 2 cm hair segment. TV viewing time was self-reported and categorised as <2, 2 < 4, 4 < 6, or ≥6 h/day. Covariates included age, sex, ethnicity, education, wealth, limiting long-standing illness, cardiovascular disease, diabetes, smoking status, alcohol intake, physical activity, body mass index, and depressive symptoms. RESULTS: The sample comprised 3555 men and women, of whom 284 (8.0%) reported watching less than 2 h of TV per day, 1160 (32.6%) 2-4 h, 1079 (30.4%) 4-6 h, and 1032 (29.0%) ≥6 h. Mean hair cortisol concentrations for those spending <2, 2 < 4, 4 < 6, and ≥6 h per day watching TV were 0.862, 0.880, 0.889, and 0.934 log pg/mg, respectively. Differences between groups were not statistically significant in unadjusted (p = .088) or adjusted (p = .663) models. CONCLUSION: In a large sample of older adults in England, self-reported sedentary behaviour was not associated with a biomarker of chronic stress.