Leading the way together: a cluster randomised controlled trial of the 5R Shared Leadership Program in older adult walking groups.

BACKGROUND: With a rapidly ageing society, healthy ageing has become a key challenge. Engagement in physical activity, and particularly walking, is a key strategy that contributes to healthy ageing amongst older adults. The purpose of the present study was to evaluate the efficacy of a group walking program for older adults that incorporates the 5R Shared Leadership Program (5RS). By implementing a structure of shared leadership and strengthening peer leaders' identity leadership, 5RS aims to cultivate a shared social identity amongst participants, which has in other contexts been associated with greater performance and well-being. METHODS: A cluster randomised controlled trial was conducted to test the efficacy of the 5RS group walking program on group identification, group cohesion, walking activity, and well-being, compared to a regular group walking program for older adults. Nineteen older adult walking groups (i.e., the clusters; N = 503; Mage = 69.23 years, SD = 6.68) all participated in a 12-week structured group walking program. Nine walking groups (n = 304) were randomly assigned to the intervention in which participants received the 5RS program in addition to regular group walking. RESULTS: 5RS was successful in strengthening the identity leadership qualities of the appointed peer leaders. Multilevel regressions showed that 5RS succeeded in increasing group cohesion and walking activity to a greater extent than a regular group walking program, while participants' group identification and well-being increased to a similar extent in both conditions. Furthermore, structural equation modelling revealed that group identification mediated the impact of peer leaders' identity leadership on group cohesion and well-being (but not walking activity). CONCLUSION: By harnessing the capacity of the group and its peer leaders, the 5RS program offers a promising intervention to engage older adults in physical activity. TRIAL REGISTRATION: The study was retrospectively registered as clinical trial on 9 September 2021 ( NCT05038423 ).

Impact of continuous vs. interval training on oxygen extraction and cardiac function during exercise in type 2 diabetes mellitus.

PURPOSE: Exercise training improves exercise capacity in type 2 diabetes mellitus (T2DM). It remains to be elucidated whether such improvements result from cardiac or peripheral muscular adaptations, and whether these are intensity dependent. METHODS: 27 patients with T2DM [without known cardiovascular disease (CVD)] were randomized to high-intensity interval training (HIIT, n = 15) or moderate-intensity endurance training (MIT, n = 12) for 24 weeks (3 sessions/week). Exercise echocardiography was applied to investigate cardiac output (CO) and oxygen (O2) extraction during exercise, while exercise capacity [([Formula: see text] (mL/kg/min)] was examined via cardiopulmonary exercise testing at baseline and after 12 and 24 weeks of exercise training, respectively. Changes in glycaemic control (HbA1c and glucose tolerance), lipid profile and body composition were also evaluated. RESULTS: 19 patients completed 24 weeks of HIIT (n = 10, 66 ± 11 years) or MIT (n = 9, 61 ± 5 years). HIIT and MIT similarly improved glucose tolerance (pTime = 0.001, pInteraction > 0.05), [Formula: see text] (mL/kg/min) (pTime = 0.001, pInteraction > 0.05), and exercise performance (Wpeak) (pTime < 0.001, pInteraction > 0.05). O2 extraction increased to a greater extent after 24 weeks of MIT (56.5%, p1 = 0.009, pTime = 0.001, pInteraction = 0.007). CO and left ventricular longitudinal strain (LS) during exercise remained unchanged (pTime > 0.05). A reduction in HbA1c was correlated with absolute changes in LS after 12 weeks of MIT (r = - 0.792, p = 0.019, LS at rest) or HIIT (r = - 0.782, p = 0.038, LS at peak exercise). CONCLUSION: In patients with well-controlled T2DM, MIT and HIIT improved exercise capacity, mainly resulting from increments in O2 extraction capacity, rather than changes in cardiac output. In particular, MIT seemed highly effective to generate these peripheral adaptations. TRIAL REGISTRATION: NCT03299790, initially released 09/12/2017.

Asymptomatic type 2 diabetes mellitus display a reduced myocardial deformation but adequate response during exercise.

BACKGROUND AND PURPOSE: The development of myocardial fibrosis is a major complication of Type 2 diabetes mellitus (T2DM), impairing myocardial deformation and, therefore, cardiac performance. It remains to be established whether abnormalities in longitudinal strain (LS) exaggerate or only occur in well-controlled T2DM, when exposed to exercise and, therefore, cardiac stress. We therefore studied left ventricular LS at rest and during exercise in T2DM patients vs. healthy controls. METHODS AND RESULTS: Exercise echocardiography was applied with combined breath-by-breath gas exchange analyses in asymptomatic, well-controlled (HbA1c: 6.9 ± 0.7%) T2DM patients (n = 36) and healthy controls (HC, n = 23). Left ventricular LS was assessed at rest and at peak exercise. Peak oxygen uptake (V̇O2peak) and workload (Wpeak) were similar between groups (p > 0.05). Diastolic (E, e's, E/e') and systolic function (left ventricular ejection fraction) were similar at rest and during exercise between groups (p > 0.05). LS (absolute values) was significantly lower at rest and during exercise in T2DM vs. HC (17.0 ± 2.9% vs. 19.8 ± 2% and 20.8 ± 4.0% vs. 23.3 ± 3.3%, respectively, p < 0.05). The response in myocardial deformation (the change in LS from rest up to peak exercise) was similar between groups (+ 3.8 ± 0.6% vs. + 3.6 ± 0.6%, in T2DM vs. HC, respectively, p > 0.05). Multiple regression revealed that HDL-cholesterol, fasted insulin levels and exercise tolerance accounted for 30.5% of the variance in response of myocardial deformation in the T2DM group (p = 0.002). CONCLUSION: Myocardial deformation is reduced in well-controlled T2DM and despite adequate responses, such differences persist during exercise. TRIAL REGISTRATION: NCT03299790, initially released 09/12/2017.

Baseline sensorimotor GABA levels shape neuroplastic processes induced by motor learning in older adults.

Previous research in young adults has demonstrated that both motor learning and transcranial direct current stimulation (tDCS) trigger decreases in the levels of gamma-aminobutyric acid (GABA) in the sensorimotor cortex, and these decreases are linked to greater learning. Less is known about the role of GABA in motor learning in healthy older adults, a knowledge gap that is surprising given the established aging-related reductions in sensorimotor GABA. Here, we examined the effects of motor learning and subsequent tDCS on sensorimotor GABA levels and resting-state functional connectivity in the brains of healthy older participants. Thirty-six older men and women completed a motor sequence learning task before receiving anodal or sham tDCS to the sensorimotor cortex. GABA-edited magnetic resonance spectroscopy of the sensorimotor cortex and resting-state (RS) functional magnetic resonance imaging data were acquired before and after learning/stimulation. At the group level, neither learning nor anodal tDCS significantly modulated GABA levels or RS connectivity among task-relevant regions. However, changes in GABA levels from the baseline to post-learning session were significantly related to motor learning magnitude, age, and baseline GABA. Moreover, the change in functional connectivity between task-relevant regions, including bilateral motor cortices, was correlated with baseline GABA levels. These data collectively indicate that motor learning-related decreases in sensorimotor GABA levels and increases in functional connectivity are limited to those older adults with higher baseline GABA levels and who learn the most. Post-learning tDCS exerted no influence on GABA levels, functional connectivity or the relationships among these variables in older adults.

Exercise capacity is related to attenuated responses in oxygen extraction and left ventricular longitudinal strain in asymptomatic type 2 diabetes patients.

AIMS: Type 2 diabetes mellitus (T2DM) is associated with reduced exercise capacity and cardiovascular diseases, both increasing morbidity and risk for premature death. As exercise intolerance often relates to cardiac dysfunction, it remains to be elucidated to what extent such an interplay occurs in T2DM patients without overt cardiovascular diseases. Design: Cross-sectional study, NCT03299790. METHODS AND RESULTS: Fifty-three T2DM patients underwent exercise echocardiography (semi-supine bicycle) with combined ergospirometry. Cardiac output (CO), left ventricular longitudinal strain (LS), oxygen uptake (O2), and oxygen (O2) extraction were assessed simultaneously at rest, low-intensity exercise, and high-intensity exercise. Glycaemic control and lipid profile were assessed in the fasted state. Participants were assigned according to their exercise capacity being adequate or impaired (EXadequate: O2peak <80% and EXimpaired: O2peak ≥80% of predicted O2peak) to compare O2 extraction, CO, and LS at all stages. Thirty-eight participants (EXimpaired: n = 20 and EXadequate: n = 18) were included in the analyses. Groups were similar regarding HbA1c, age, and sex (P > 0.05). At rest, CO was similar in the EXimpaired group vs. EXadequate group (5.1 ± 1 L/min vs. 4.6 ± 1.4 L/min, P > 0.05) and increased equally during exercise. EXimpaired patients displayed a 30.7% smaller increase in O2 extraction during exercise compared to the EXadequate group (P = 0.016) which resulted in a lower O2 extraction at high-intensity exercise (12.5 ± 2.8 mL/dL vs. 15.3 ± 3.9 mL/dL, P = 0.012). Left ventricular longitudinal strain was similar at rest but increased significantly less in the EXimpaired vs. EXadequate patients (1.9 ± 2.5% vs. 5.9 ± 4.1%, P = 0.004). CONCLUSIONS: In asymptomatic T2DM patients, an impaired exercise capacity is associated with an impaired response in oxygen extraction and myocardial deformation (LS). TRIAL REGISTRY: Effect of High-intensity Interval Training on Cardiac Function and Regulation of Glycemic Control in Diabetic Cardiomyopathy (https://clinicaltrials.gov/ct2/show/NCT03299790).

Cardiac Function is Preserved in Adolescents With Well-Controlled Type 1 Diabetes and a Normal Physical Fitness: A Cross-Sectional Study.

OBJECTIVES: Cardiovascular diseases and exercise intolerance elevate mortality in type 1 diabetes (T1D). Left ventricular systolic and diastolic function are already affected in adolescents with T1D, displaying poor glycemic control (glycated hemoglobin [A1C]>7.5%) and exercise intolerance. We investigated the extent to which left ventricular function is affected by disease severity/duration and whether this is related to exercise capacity. METHODS: Transthoracic echocardiography was performed in 19 adolescents with T1D (14.8±1.9 years old, A1C 7.4±0.9%) and 19 controls (14.4±1.3 years old, A1C 5.3±0.2%), matched for age and Tanner stage. Diastolic and systolic (ejection fraction [EF]) function were assessed. Cardiopulmonary exercise testing was used to evaluate exercise capacity, as measured by peak oxygen uptake (VO2peak). RESULTS: VO2peak and left ventricular systolic and diastolic function were similar in both groups. Within the T1D group, EF was negatively associated with disease duration (r=-0.79 corrected for age, standardized body mass index, glucose variability and VO2peak; p=0.011). Regression analyses revealed that 37.6% of the variance in EF could be attributed to disease duration. CONCLUSIONS: Although left ventricular systolic and diastolic function are preserved in T1D with adequate exercise capacity, disease duration negatively affects EF. The detrimental effects of T1D seem to be driven by disease duration, rather than by disease severity, at least during adolescence. Young patients with T1D may, therefore, benefit from cardiovascular evaluation in order to detect cardiovascular abnormalities early in the disease course, and, therefore, improve long-term cardiovascular health.