The aim of this feasibility study was to describe and report data relevant to the acceptability of an exercise intervention (reduced-exertion, high-intensity interval training) in non-diabetic hyperglycaemia patients delivered in a National Health Service setting.

Background Physical activity and exercise interventions to improve health frequently bring about intended effects under ideal circumstances but fail to demonstrate effectiveness when translated to demonstrable benefits in real-world contexts. The aim of this feasibility study was to describe and report data relevant to the acceptability of an exercise intervention (reduced-exertion, high-intensity interval training) in non-diabetic hyperglycaemia (NDH) patients delivered in a National Health Service (NHS) setting.

Individuals with NDH are an intermediary group of patients whose blood glucose levels are higher than normal but not high enough to be diagnosed as diabetic. Such hyperglycaemic blood glucose excursions in 'pre-diabetic' states contribute to the development of macro- and micro-vascular disease risk and increases the risk of developing overt type 2 diabetes. Interventions - such as increased physical activity - for individuals who are diagnostically considered to have NDH are high priority, as they provide a substantial opportunity for preventing future burden of diabetes on patients, the NHS, and the economy.

Evidence supporting the efficacy of exercise and physical activity as preventative or therapeutic treatments for a range of chronic diseases, including obesity and diabetes, is incontrovertible. However, exercise adherence is considered a significant issue. The most commonly cited barrier to undertaking physical activity is perceived 'lack of time'. Consequently, there has been a recent interest in high-intensity interval training (HIT) which is characterised by brief periods of repeated very high-intensity exercise interspersed with longer periods of recovery. More recently attempts have been made to modify HIT to make it more time-efficient and tolerable. This approach is known as reduced-exertion, high-intensity interval training (REHIT). In this study, issues of acceptability and feasibility were considered when implementing a REHIT intervention into usual care within an NHS setting.

Methods The purpose was to assess whether it would be appropriate to progress to a larger-scale pragmatic trial, and to optimise the design and conduct of any such trial. The intention was to recruit 40 participants from a single centre (specialist diabesity centre). Patients were eligible to take part if they were diagnostically defined as non-diabetic hyperglycaemic based on a glycated haemoglobin value of 42-46 mmol·mol. Methodological issues were used to analyse problems that arose.

Inclusion Criteria:

• Accessing the NHS Trust Weight Management Service (Specialist Diabesity Clinic)
• Aged between 18 and 65 years (inclusive)
• Diagnosed as NDH (using standard criteria)
• Male or female
• Any ethnicity
• Not currently partaking in a new structured exercise intervention
• Considered low or medium risk for exercise using standard risk stratification [37]

Exclusion Criteria:

• < 18 years and ≥ 66 years
• Currently partaking in a new structured exercise intervention
• Euglycaemic
• Diagnosed with type 1 or type 2 diabetes; taking insulin; history of end stage liver or kidney disease, neuropathy or retinopathy; has hypertension that cannot be controlled by standard medication; has cardiovascular disease, or another contraindication to exercise
• Considered high risk for exercise using standard risk stratification [37]
• Unable to adequately understand verbal explanations and written information given in English (there were no funds available for translation services)

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.