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New Research into Diabetes and Exercise Revealed

A fitness technique popular among cyclists could be key to helping those with diabetes exercise for longer, according to a new first-of-its-kind study. 

People with type 1 diabetes are at an increased risk of cardiovascular disease, and are encouraged to take regular exercise. 

Yet that’s not as simple as it sounds - with many patients struggling to tolerate any sort of significant fitness regime. 

Now a team led by experts at Liverpool Hope University has investigated the links between exercise tolerance and type 1 diabetes - discovering for the first time how the ‘VO2 kinetics’ - ie the time it takes for the body to glean the additional energy needed for exercise - is actually much slower in type 1 diabetes patients compared with healthy people. 

But the sport scientists also found that a short ‘priming’ warm-up exercise - which involved a short period of hard but sustainable pedalling on an exercise bike - just before a training session actually sped up the VO2 kinetics. 

And this in turn caused ‘critical power’ - the highest intensity before the onset of fatigue - to be boosted in diabetes patients, by around 8 per cent. 

That, say the academics, could help diabetes sufferers exercise at higher intensities and for longer, potentially warding off heart disease. 

The results, published in the Journal of Applied Physiology, ‘have important implications for the development of interventions to enhance aerobic fitness in this patient group’.

Lead author Dr Simon Marwood, Associate Professor in Physiology of Hope’s School of Health Sciences, says: “Patients with type 1 diabetes demonstrated slower VO2 kinetics when compared to healthy controls. 

“Furthermore, a prior bout of high-intensity exercise speeded oxygen uptake kinetics and increased critical power in people with type 1 diabetes. 

“These findings highlight the potential for other interventions, perhaps nutritional or pharmacological, that also speed VO2 kinetics for enhancing exercise tolerance in this condition.”

Dr Marwood, along with co-authors Dr Richie Goulding and Associate Professor Associate Denise Roche, performed the study in two phases.

Phase one saw 17 males with type 1 diabetes, and 17 healthy males without type 1 diabetes - with an average age in their early to late 30s - put through their paces on a laboratory exercise bike. 

Various measurements were taken, including VO2 peak - the point at which oxygen uptake no longer increases with an increase in workload - and blood glucose levels, while being pushed to exhaustion. 

And Dr Marwood found oxygen uptake kinetics - and general aerobic fitness - were significantly compromised in the group with diabetes - equivalent to around 30 years plus of ageing compared with healthy individuals. 

He says: “Aerobic fitness is an important determinant of cardiovascular risk and 

cardiovascular risk is already substantially higher in individuals with type 1 diabetes compared to individuals without diabetes. 

“The findings from Part 1 are therefore clinically relevant to individuals living with type 1 diabetes, suggesting that interventions aimed at mitigating cardiovascular risk and improving life expectancy in type 1 diabetes necessitate a strong focus on improvement of aerobic fitness.”

Part two of the trial focused on seven participants with diabetes. 

During a series of tests, they were asked to exercise to failure in order to establish their ‘critical power’. 

And these bursts of activity were performed both with and without an initial ‘priming’ exercise. 

This priming consisted of 3 minutes of gentle ‘baseline’ pedalling, before a sharp ramp up for 6 minutes, followed by a rest of seven minutes before the main test began. 

Scientists found the that the priming exercise ‘resulted in faster VO2 kinetics and a greater critical power when compared to the control condition’ with an ‘increase in critical power of 8% compared to the control condition’. 

Dr Marwood adds: “This is the first evidence in this patient group that a simple warm up exercise can enhance subsequent exercise performance. 

“And it could therefore be used as an aid to improve training intensity, or simply to overcome the barriers in the capacity to undertake exercise at all.”

The team of scientists made another surprising finding. 

Contrary to expectations, he found that the issue was not about how oxygen is delivered to the body - but about how muscles are able to utilise it on a cellular level, with diabetes patients compromised in this respect. 

He adds: “In type 1 diabetes, therefore, our data strongly suggest that VO2 kinetics, and in turn critical power and exercise tolerance, are primarily limited by an impaired ability to use oxygen in the muscle cell, rather than impairments in the delivery of oxygen.

“Furthermore, these derangements to cellular metabolism can, at least partially, be reversed via a prior bout of priming exercise.”

What’s more, this is the first time such a conclusion has been drawn. 

The research concludes: “This is the first assessment of VO2 kinetics in adults with type 1 diabetes, and we demonstrate a profound slowing of the VO2 kinetics in the type 1 diabetes group relative to the control group. 

“The injurious effects of type 1 diabetes on the aerobic phenotype noted herein are likely to contribute to the burden associated with the disease and its secondary complications.”

Addressing the priming exercise, Dr Marwood states: “Indeed, our finding of impairments in each of the most important parameters of aerobic function in type 1 diabetes supports recent suggestions that the current physical activity recommendations may be insufficient to offset the deleterious effects of this disorder on aerobic function. 

“Moreover, our data suggest that interventions that can specifically improve the speed of the VO2 kinetics will enhance exercise tolerance in this population.”

Type 1 diabetes, sometimes known as juvenile diabetes or insulin-dependent diabetes, is a condition in which the pancreas produces little or no insulin - with Insulin being a hormone required to allow sugar to enter cells to produce energy.

According to the Juvenile Diabetes Research Foundation, around 400,000 people are currently living with type 1 diabetes in the UK, including around 29,000 children.

The number of new diagnoses of type 1 diabetes  is increasing by about four per cent each year.

And the UK also has one of the highest rates of type 1 diabetes in the world - for reasons that are so far unknown. 

Meanwhile the benefits of ‘priming’ exercises were first established in the early Noughties by Dr Mark Burnley, of the University of Kent, and Andy Jones, Professor of Applied Physiology at the University of Exeter

Jones has made global headlines in recent years as scientist and external advisor for Nike's famous ‘Breaking2’ project, a mission to break the two-hour barrier for the marathon.


Published on 25/09/2020