Blood Glucose During High Altitude Trekking in Young Healthy Adults.

Reid, Ly-Anh, Jordan L Rees, Miranda Kimber, Marina James, Graeme M Purdy, Megan Smorschok, Lauren E Maier, Normand G. Boulé, Trevor A. Day, Margie H. Davenport, and Craig D. Steinback. Blood glucose during high altitude trekking in young healthy adults. High Alt Med Biol. 00:00-00, 2024. Introduction: High altitude trekking is becoming more popular and accessible to an increased number of people. Simultaneously, there is a worldwide rise in the prevalence of metabolic diseases. The purpose of this study was to examine the impact of a gradual trekking ascent to high altitude on continuous glucose monitoring outcomes including fasting, mean 24-hour, postprandial, and post-75 g modified oral glucose tolerance test. This study also investigated the relationship between physical activity intensity, high altitude, and glucose concentrations. Methods: Individuals (n = 9) from Alberta, Canada participated in a 2-week trek in the Khumbu Valley in Nepal, ascending by foot from 2,860 m to 5,300 m (∼65 km) over 10 days. A standardized 75 g oral glucose load was given to participants at four different altitudes (1,130 m, 3,440 m, 3,820 m, 5,160 m). Physical activity (Actigraph accelerometry) and interstitial glucose (iPro2, Medtronic) were measured continuously during the trek. Results: Fasting and mean 24-hour glucose concentrations were not different between altitudes. However, 2-hour post dinner glucose and 2-hour post lunch glucose, AUC concentrations were different between altitudes. The relationship between physical activity intensity and glucose was not influenced by increasing altitudes. Conclusion: Our findings suggest that glucose regulation is largely preserved at high altitude; however, inconsistency in our postprandial glucose concentrations at altitude warrants further investigation.

Exercise Preferences, Barriers, and Facilitators of Individuals With Cancer Undergoing Chemotherapy Before Stem Cell Transplantation: A Mixed-Methods Study.

BACKGROUND: Exercise can help mitigate side effects of hematopoietic stem cell transplantation (HSCT), particularly when initiated before HSCT. However, the exercise-related barriers, facilitators, and preferences of this population remain unclear. OBJECTIVE: This study aimed to explore the patient experience to inform future implementation of a prehabilitation intervention. INTERVENTIONS/METHODS: A 2-phase sequential explanatory mixed-methods study was conducted using (1) cross-sectional survey and (2) focus groups. Survey questions aligned with the Theoretical Domains Framework. Focus group data were analyzed using a directed content analysis approach, followed by inductive thematic analysis to generate themes that represented the exercise-related barriers, facilitators, and preferences of participants. RESULTS: Twenty-six participants completed phase 1 (n = 22 with multiple myeloma). Fifty percent of participants (n = 13) were fairly/very confident in their ability to exercise pre-HSCT. Eleven participants completed phase 2. Exercise barriers included knowledge/skill limitations, inadequate healthcare provider support, and the emotional toll of treatment. Facilitators included social support and goals. Exercise preferences were related to 2 themes: (1) program structure (subthemes: prescription and scheduling, mode of delivery) and (2) support (subthemes: support from personnel, tailoring, and education). CONCLUSION: Key exercise-related barriers included knowledge limitations, disease/treatment effects, and inadequate support. Prehabilitation should be tailored, flexible, and include education and a virtual or hybrid delivery model in this population. IMPLICATIONS FOR PRACTICE: Nurses are well positioned to identify functional limitations and counsel and refer patients to exercise programming and/or physiotherapy services. Including an exercise professional in the pretransplant care team would provide key supportive care assistance for the nursing team.

Exploring participant perceptions of a virtually supported home exercise program for people with multiple myeloma using a novel eHealth application: a qualitative study.

INTRODUCTION: Supervision, tailoring, and flexibility have been proposed as key program elements for delivering successful exercise programs for people with multiple myeloma (MM). However, no studies to date have evaluated the acceptability of an intervention employing these components. The aim of this study was to determine the acceptability of a virtually supported exercise program and eHealth application for people with MM. METHODS: A qualitative description approach was used. One-on-one interviews were conducted with participants who completed the exercise program. Content analysis was used to analyze verbatim transcripts from interviews. RESULTS: Twenty participants were interviewed (64.9 ± 6.7 years of age, n = 12 females). Participants had positive perceptions of the exercise program. Two themes emerged related to strengths/limitations: One Size Does Not Fit All (sub-themes: Supportive & Responsive Programming and Diverse Exercise Opportunities), and App Usability. Supportive and Responsive Programming was a main strength of the program, characterized as programming that was tailored, involved active support, and delivered by appropriate personnel. The inclusion of Diverse Exercise Opportunities was also regarded as a strength, as it accommodated the preferences of all participants. Related to App Usability, participants felt the app was simple and user friendly but had a few less intuitive components. CONCLUSION: The virtually supported exercise program and eHealth application were acceptable for people with MM. Programs should employ tailoring, active support, and appropriate personnel to bolster acceptability and include both supervised and flexible exercise formats. eHealth apps should be simple to use so technology proficiency is not a barrier to participation.

Feasibility of a tailored and virtually supported home exercise program for people with multiple myeloma using a novel eHealth application.

Introduction: eHealth exercise interventions have the unique ability to leverage the benefits of in-person programming (tailoring and supervision) with the benefits of home programming (flexibility). There may be a role for eHealth-delivered exercise for people with multiple myeloma (MM), as exercise tailoring and supervision are critical for successful outcomes due to the significant impacts/risks of myeloma-related side effects. The purpose of this study was to determine the safety, feasibility, and preliminary efficacy of a 12-week virtually supported eHealth exercise program. Methods: Participants with MM completed a 12-week virtually supported home exercise program involving virtually supervised group workouts, independent workouts, and aerobic exercise. Tailoring was facilitated by the functionality of HEAL-Me, a novel eHealth app. Participants completed virtual fitness assessments and questionnaires at baseline and week 12. Results: Twenty-nine participants consented, 26 completed all follow-up testing (90%). Exercise adherence was 90% (group), 83% (independent), and 90% (aerobic). No serious adverse events (grade ≥3) occurred. Significant improvements were found for quality of life and physical fitness. There was a high level of program/app satisfaction: 96% of participants agreed or strongly agreed that the exercise program was beneficial, 93% found it enjoyable, 89% were satisfied or very satisfied with delivery through the HEAL-Me app, and 48% felt that the eHealth program helped them manage cancer-related symptoms and side-effects. Conclusion: An eHealth intervention that is individually tailored and includes virtual supervision and active support from the healthcare team is feasible and acceptable to people with MM. The findings from this study warrant investigation using a large-scale randomized controlled trial.

Heal-me PiONEer (personalized online nutrition and exercise): An RCT assessing 2 levels of app-based programming in individuals with chronic disease.

Background App-based strategies are a promising solution to deliver nutrition and exercise interventions during social distancing. With limited RCT data in individuals with chronic disease, further information is required both to determine impact, and to guide delivery. The Heal-Me app is an evidence-based, theoretically informed nutrition and exercise solution that can be tailored for use across a range of individuals with chronic disease. As compared to controls receiving educational material, the aim of this study is to assess the acceptability, effectiveness, and cost of Heal-Me app programming delivered alongside two levels of dietitian and exercise-specialist support. Methods Heal-Me PiONEer is a 12-week, 3-arm RCT with randomization to one of three study groups (n=72 per group, 216 total). Group 1 (control: educational material), Group 2 (Heal-Me app + virtual group dietitian/exercise-specialist sessions), Group 3 (Heal-Me app + virtual group and 1-to-1 dietitian/exercise-specialist sessions). Inclusion criteria: adults with cancer, chronic lung disease or status post-transplantation from liver or lung transplant; previous completion of an exercise rehabilitation program; access to an internet-connected device. Study outcomes measured at study weeks 0 and 12 include: Primary - Lower Extremity Functional Scale; Secondary - virtual physical function tests, loneliness, resilience, anxiety, well-being and health-related quality of life; Exploratory outcomes - protein intake, behavioral beliefs around exercise and nutrition, adherence, adverse events, acceptability, and cost-utility. Conclusions The Heal-Me PiONEer RCT holds promise to provide a comprehensive understanding of the delivery and impact of app-based nutrition and exercise programming in a diverse group of participants with chronic disease.

Evaluating implementation and pragmatism of cancer-specific exercise programs: a scoping review.

PURPOSE: Studies in exercise oncology are increasingly evaluating the implementation of cancer-specific exercise programming in real-world settings. Evaluating current implementation efforts and identifying current research gaps may inform future implementation. This scoping review explores studies implementing cancer-specific exercise programs to determine their pragmatic characteristics and evaluate potential for translation into practice. METHODS: A systematic literature search was conducted using five databases (up to July 2020) to identify implementation studies that used qualitative or quantitative methods. Program pragmatism was evaluated using the PRECIS/RE-AIM tool. RESULTS: Fourteen articles were included for review. While programs were moderately pragmatic (average: 3.4; range: 2.8-4.2), variability was observed between scoring domains. Programs scored higher (more pragmatic) in domains typical for effectiveness studies, including participant eligibility, follow-up intensity, primary trial outcome, and analysis of primary outcome. In contrast, programs scored lower (less pragmatic) in domains aligned with implementation science, including intervention flexibility, adoption, implementation, and maintenance. Limited information was reported regarding program fidelity, adaptations, and maintenance/sustainability. CONCLUSION: Researchers should consider the pragmatism of interventions, the nuances of program adoption and implementation at the setting level, and the transition and integration of programming into the healthcare system. Future studies may benefit from the inclusion of decision-makers and implementation experts and shifting focus towards flexible programming. PRECIS/RE-AIM may facilitate the evaluation of programs throughout the study design and implementation process. IMPLICATIONS FOR CANCER SURVIVORS: The implementation of pragmatic exercise programs that are both scalable and sustainable is needed so that cancer survivors can experience exercise-related benefits beyond research settings.

Feasibility of performance-based functional assessment in brain tumour survivors.

INTRODUCTION: Rehabilitation and exercise interventions are beneficial for the physical and psychological health of cancer survivors. Current clinic-based performance status measures do not accurately capture the survivor's functioning, or rehabilitation and exercise needs. Our primary objective was to explore the feasibility of performing a performance-based functional assessment with brain tumour survivors as a means to inform needs for rehabilitation and exercise. METHODS: A feasibility study was conducted with survivors of brain and other neurological cancers attending new patient or follow-up clinics. Survivors were assessed using the Short Physical Performance Battery (SPPB), grip strength and Rosow-Breslau Physical Activity Self-Assessment (RSB). RESULTS: We approached 40 survivors with brain tumours, and 30 agreed to participate in the study. The SPPB was inversely correlated with Eastern Cooperative Oncology Group (ECOG) scores (r = -.73; p < .01), but scores on the SPPB for individuals classified as ECOG 1 ranged from 5 to 12 out of 12, indicating a large variability in functional scores within this ECOG grade. CONCLUSION: Implementation of objective functional testing is feasible in the neuro-oncology outpatient clinic. The SPPB appears to best inform the functional status of survivors with brain tumours, facilitating more individualised exercise and rehabilitation referrals.

Steady-state cerebral blood flow regulation at altitude: interaction between oxygen and carbon dioxide.

High-altitude ascent imposes a unique cerebrovascular challenge due to two opposing blood gas chemostimuli. Specifically, hypoxia causes cerebral vasodilation, whereas respiratory-induced hypocapnia causes vasoconstriction. The conflicting nature of these two superimposed chemostimuli presents a challenge in quantifying cerebrovascular reactivity (CVR) in chronic hypoxia. During incremental ascent to 4240 m over 7 days in the Nepal Himalaya, we aimed to (a) characterize the relationship between arterial blood gas stimuli and anterior, posterior and global (g)CBF, (b) develop a novel index to quantify cerebral blood flow (CBF) in relation to conflicting steady-state chemostimuli, and (c) assess these relationships with cerebral oxygenation (rSO2). On rest days during ascent, participants underwent supine resting measures at 1045 m (baseline), 3440 m (day 3) and 4240 m (day 7). These measures included pressure of arterial (Pa)CO2, PaO2, arterial O2 saturation (SaO2; arterial blood draws), unilateral anterior, posterior and gCBF (duplex ultrasound; internal carotid artery [ICA] and vertebral artery [VA], gCBF [{ICA + VA} × 2], respectively) and rSO2 (near-infrared spectroscopy). We developed a novel stimulus index (SI), taking into account both chemostimuli (PaCO2/SaO2). Subsequently, CBF was indexed against the SI to assess steady-state cerebrovascular responsiveness (SS-CVR). When both competing chemostimuli are taken into account, (a) SS-CVR was significantly higher in ICA, VA and gCBF at 4240 m compared to lower altitudes, (b) delta SS-CVR with ascent (1045 m vs. 4240 m) was higher in ICA vs. VA, suggesting regional differences in CBF regulation, and (c) ICA SS-CVR was strongly and positively correlated (r = 0.79) with rSO2 at 4240 m.

Peripheral chemoreceptor deactivation attenuates the sympathetic response to glucose ingestion.

Acute increases in blood glucose are associated with heightened muscle sympathetic nerve activity (MSNA). Animal studies have implicated a role for peripheral chemoreceptors in this response, but this has not been examined in humans. Heart rate, cardiac output (CO), mean arterial pressure, total peripheral conductance, and blood glucose concentrations were collected in 11 participants. MSNA was recorded in a subset of 5 participants via microneurography. Participants came to the lab on 2 separate days (i.e., 1 control and 1 experimental day). On both days, participants ingested 75 g of glucose following baseline measurements. On the experimental day, participants breathed 100% oxygen for 3 min at baseline and again at 20, 40, and 60 min after glucose ingestion to deactivate peripheral chemoreceptors. Supplemental oxygen was not given to participants on the control day. There was a main effect of time on blood glucose (P < 0.001), heart rate (P < 0.001), CO (P < 0.001), sympathetic burst frequency (P < 0.001), burst incidence (P = 0.01), and total MSNA (P = 0.001) for both days. Blood glucose concentrations and burst frequency were positively correlated on the control day (r = 0.42; P = 0.03) and experimental day (r = 0.62; P = 0.003). There was a time × condition interaction (i.e., normoxia vs. hyperoxia) on burst frequency, in which hyperoxia significantly blunted burst frequency at 20 and 60 min after glucose ingestion only. Given that hyperoxia blunted burst frequency only during hyperglycemia, our results suggest that the peripheral chemoreceptors are involved in activating MSNA after glucose ingestion.

Maternal cardioautonomic responses during and following exercise throughout pregnancy.

Blood pressure regulation during pregnancy is poorly understood. Cardiovagal baroreflex gain (BRG) is an important contributor to blood pressure regulation through its influence on heart rate. Heart rate fluctuations occur in response to various physiological stimuli and can be measured using heart rate variability (HRV). It is unclear how these mechanisms operate during pregnancy, particularly with regard to exercise. We examined BRG and HRV prior to, during, and following prenatal exercise. Forty-three pregnant (n = 10 first trimester (TM1), n = 17 second trimester (TM2), n = 16 third trimester (TM3)) and 20 nonpregnant (NP) women underwent an incremental peak exercise test. Beat-by-beat blood pressure (photoplethysmography) and heart rate (lead II electrocardiogram) were measured throughout. BRG (the slope of the relationship between fluctuations in systolic blood pressure and the R-R interval) and HRV (root mean square of the successive differences; RMSSD) were assessed at rest, during steady-state exercise (EX), and during active recovery. BRG decreased with gestation and was lower in the TM3 group than in the NP group (17.9 ± 6.9 ms/mm Hg vs 24.8 ± 7.4 ms/mm Hg, p = 0.017). BRG was reduced during EX in all groups. Resting HRV (RMSSD) also decreased with gestation and was lower in the TM3 group than in the NP group (29 ± 17 ms vs 48 ± 20 ms, p < 0.001). RMSSD was blunted during EX in all groups compared with rest. During active recovery, RMSSD was further blunted compared with EX in the NP group but not during pregnancy (TM1, TM2, and TM3). Compared with the nonpregnant controls, the pregnant women had lower BRG and HRV at rest, but comparable cardioautonomic control during both exercise and active recovery following peak exercise.

Spleen reactivity during incremental ascent to altitude.

The spleen contains a reservoir of red blood cells that are mobilized into circulation when under physiological stress. Despite the spleen having an established role in compensation to acute hypoxia, no previous work has assessed the role of the spleen during ascent to high altitude. Twelve participants completed 2 min of handgrip exercise at 30% of maximal voluntary contraction at 1,045, 3,440, and 4,240 m. In a subset of eight participants, an infusion of phenylephrine hydrochloride was administered at a dosage of 30 µg/l of predicted blood volume at each altitude. The spleen was imaged by ultrasound via a 2- to 5.5-MHz curvilinear probe. Spleen volume was calculated by the prolate ellipsoid formula. Finger capillary blood samples were taken to measure hematocrit. Spleen images and hematocrit were taken both before and at the end of both handgrip and phenylephrine infusion. No changes in resting spleen volume were observed between altitudes. At low altitude, the spleen contracted in response to handgrip [272.8 ml (SD 102.3) vs. 249.6 ml (SD 105.7), P = 0.009], leading to an increase in hematocrit (42.6% (SD 3.3) vs. 44.3% (SD 3.3), P = 0.023] but did not contract or increase hematocrit at the high-altitude locations. Infusion of phenylephrine led to spleen contraction at all altitudes, but only lead to an increase in hematocrit at low altitude. These data reveal that the human spleen may not contribute to acclimatization to chronic hypoxia, contrary to its response to acute sympathoexcitation. These results are explained by alterations in spleen reactivity to increased sympathetic activation at altitude. NEW & NOTEWORTHY The present study demonstrated that, despite the known role of the human spleen in increasing oxygen delivery to tissues during acute hypoxia scenarios, the spleen does not mobilize red blood cells during ascent to high altitude. Furthermore, the spleen's response to acute stressors at altitude depends on the nature of the stressor; the spleen's sensitivity to neurotransmitter is maintained, while its reflex response to stress is dampened.

Maternal Physical Activity Is Associated With Improved Blood Pressure Regulation During Late Pregnancy.

BACKGROUND: Cardiovagal baroreflex gain (cBRG) reflects an individual's ability to buffer swings in blood pressure. It is not well understood how this mechanism is influenced by physical activity in pregnancy. Because pregnant women tend to engage in low levels of moderate-to-vigorous physical activity (MVPA) and high levels of sedentary behaviour, we sought to determine the influence of MVPA and sedentary behaviour on cBRG and mean arterial pressure (MAP) in pregnancy. METHODS: Fifty-eight third trimester (31.9 ± 3.0 weeks) normotensive pregnant women (31.2 ± 2.8 years) were tested. Heart rate (electrocardiogram) and blood pressure (systolic blood pressure and MAP; finger photoplethysmography) were collected on a beat-by-beat basis, and averaged over 3 minutes of rest. Spontaneous cBRG was calculated as the slope of the relationship between fluctuations in systolic blood pressure and heart rate. Objective measures of MVPA and sedentary behaviour were collected over a 7-day period using an ActiGraph accelerometer (model wGTX3-BT; ActiGraph LLC, Pensacola, FL). RESULTS: Participants spent 67.5 ± 7.9% of waking hours engaged in sedentary behaviour, and performed 68.6 ± 91.9 minutes of MVPA per week. Sedentary behaviour was not related to cBRG (r = -0.035; P = 0.793) or MAP (r = -0.033; P = 0.803). However, MVPA was positively associated with cBRG (r = 0.315; P = 0.016), but not MAP (r = -0.115; P = 0.389). The association between MVPA and cBRG remained significant after controlling for age, pre-pregnancy body mass index, gestational age, and wear time (r = 0.338; P = 0.013), indicating that women who engaged in greater amounts of MVPA showed increased cBRG. CONCLUSIONS: Our data suggest that increased MVPA, but not necessarily reduced sedentary behaviour, might be beneficial for reflex control of blood pressure during pregnancy.