Association between accelerometer-measured physical activity, glucose metabolism, and waist circumference in older adults

Sustained decreases in sedentary time and increases in physical activity are associated with preservation of estimated β-cell function in individuals with type 2 diabetes

AIMS

In the Italian Diabetes and Exercise Study_2, a counselling intervention produced modest but sustained increments in moderate-to vigorous-intensity physical activity (MVPA), with reallocation of sedentary-time (SED-time) to light-intensity physical activity (LPA). This post hoc analysis evaluated the impact of intervention on estimated β-cell function and insulin sensitivity.

METHODS

Patients with type 2 diabetes were randomized to one-month counselling once-a-year or standard care for 3 years. The HOmeostatic Model Assessment-2 (HOMA-2) method was used for estimating indices of β-cell function (HOMA-B%), insulin sensitivity (HOMA-S%), and insulin resistance (HOMA-IR); the disposition index (DI) was estimated as HOMA-β%/HOMA-IR; MVPA, LPA, and SED-time were objectively measured by accelerometer.

RESULTS

HOMA-B% and DI decreased in control group, whereas HOMA-B% remained stable and DI increased in intervention group. Between-group differences were significant for almost all insulin secretion and sensitivity indices. Changes in HOMA-B% and DI correlated with SED-time, MVPA and LPA. Changes in HOMA-B%, DI, and all indices were independently predicted by changes in SED-time (or LPA), MVPA, and BMI (or waist circumference), respectively.

CONCLUSIONS

In individuals with type 2 diabetes, increasing MVPA, even without achieving the recommended target, is effective in maintaining estimated β-cell function if sufficient amounts of SED-time are reallocated to LPA.

Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA)

Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults.