Exercise as it relates to Disease/Can resistance training have a positive effect on older adults with type 2 diabetes?

An analysis of the journal article A Randomized Controlled Trial of Resistance Exercise Training to Improve Glycemic Control in Older Adults With Type 2 Diabetes

What is the background to this research?

Type 2 diabetes is a mostly preventable, lifestyle disease whereby a person becomes resistant to insulin produced in the body, or where the body doesn't produce enough insulin. Since this study was published, the prevalence of type 2 diabetes has increased globally with the World Health Organization citing an increase of people with diabetes from 108 million in 1980 to 422 million in 2014. Lifestyle changes are a primary treatment, risk factors include: Low activity levels and poor diet.
The aim of this study was to determine the effects of progressive resistance training(PRT) specifically in older, Latin-American adults with type 2 diabetes.

Where is the research from?

The research was conducted at the General Clinic Research Center at New England Medical Center and the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University.

What kind of research was this?

The study was a randomised controlled trial (RCT) of a physical activity intervention over 16 weeks. The research has a clear and limited study population - it outlined exclusion criteria (e.g. alcoholism, existing training) and inclusions (e.g. age, heritage). This created a very specific population for the study, allowing for stronger conclusions to be made from the results. It also reduces the ability to generalise these results to individuals/groups who fall outside the identified limitations.

What did the research involve?

The population group comprised 62 Latin-American men (n=22) and women (n=40) from Boston communities. Subjects were 55+ years old, had type 2 diabetes for at least 3 years and were otherwise eligible for the trial (did not meet the exclusion criteria). The 62 subjects were randomly placed in either the control group or the exercise group. Compliance to the training was 90+/-10%. Both groups underwent baseline, mid-study and post-study testing. The exercise group completed 3 PRT sessions of 45mins each, per week and intensity increased over time. The RCT was the best method to use as observed effects can easily be attributed to the intervention being evaluated. However, the research demonstrated some limitations in its design:

• The subject recruitment method is not clear, only that they were 'contacted' - allowing for criticism based on this unidentified factor.
• The authors acknowledge that one limitation was that the control group did not receive the same contact time as the exercise group.

What were the basic results?

The results of the study showed improvements after the PRT intervention compared to the control in most areas.

• Improved glycosylated haemoglobin levels in PRT group(from 8.7% to 7.6%). Control had no change.
• Improved muscle glycogen stores in PRT group(from 60.3+/-3.9 to 79.9+/-5.0 mmol glucose/kg muscle). Control decreased 61.4+/-7.7 to 47.2+/-6.7 mmol glucose/kg muscle .
• 72% of PRT participants decreased their use of medication. Control increased use 42%.
• Improved systolic blood pressure in PRT group(Decreased 9.7+/-1.6mmHg). Control increased 7.7+/-1.9mmHg.
• Decreased trunk fat mass in PRT group(-0.7+/-0.1 kg). Control increased 0.8+/-0.1 kg.
• Increased muscle mass in PRT group(+1.2+/-0.2 kg). Control decreased 0.1+/-0.1 kg.

What conclusions can we take from this research?

The data provided evidence of a separate (un-hypothesised) finding of this study; that self-reported leisure and household physical activities outside PRT sessions increased among exercisers (compared to control subjects). Further research could be undertaken in other population groups and/or other types of exercise sessions to establish a broader correlation between prescribed training and increasing self reported leisure/physical activities. Since this study was published, a 2007 paper confirmed that exercise has a positive effect on glycemic control and further suggested that combining aerobic and resistance training is even more beneficial.

This research demonstrates a positive outcome for older adults with type 2 diabetes. Noting however, that the subjects were Latin-Americans from the greater Boston area only, meaning that any conclusions drawn do not necessarily correlate to other population groups (as would suggest the title which only refers 'older adults'). Lifestyle choices, which are also type 2 diabetes risk factors (activity levels; diet; smoking), can vary considerably for other population groups, which may result in different outcomes.

Practical advice

The positive results of the study present a good argument for people with type 2 diabetes to engage in PRT. However, there are considerations to make for a real life situation. As a part of the research design, subjects were able to taxi to/from the gym, and participate in PRT sessions that require professional planning and supervision. Both of these aspects of the research may not be financially practicable, notably for disadvantaged population groups.

If an individual was to take on a PRT program, it would need to be implemented by a professional to reduce the risk of injury and increase the likelihood of achieving results.

Further information/resources

For information on Type 2 diabetes - Diabetes Australia
Contact an Exercise Physiologist to enquire about PRT sessions - ESSA
For an introduction to glucose control and exercise - ADA 'get started safely'