Exercise as it relates to Disease/It's not too late to improve Glycemic Control - Exercise Intervention in Older Type 2 Diabetics/It's not too late to improve Glycemic Control - Exercise Intervention in Older Type 2 Diabetics

Topic Article
Castaneda, C., Layne, J.E, Munoz-Orians, L., GORDON, P.L., Walsmith, J., Foldvari, M., Roubenoff, R., Tucker, K.L., Nelson, M.E. (2002). A Randomized Control Trial of Resistance Exercise Training to Improve Glycemic Control in Older Adults With Type 2 Diabetes. Diabetes Care, 25(12), 2335-2341.

Background
 Diabetes 

Diabetes can be classified or diagnosed by hyperglycemia arising from insufficient insulin secretion or decreased insulin action or a combination of these. The major risk factors associated with diabetes and this prolonged hyperglycaemic state are in extreme cases failure of multiple organs including the eyes, kidneys, nerves, heart and blood vessels.

In recent times the global prevalence of diabetes has sky-rocketed, growing from 4.7% in 1980 to 8.5% in 2014, nearly doubling the amount of adult diabetics worldwide. Due to the risks factors being extremely severe and the prevalence rate growing exponentially over recent times, it makes it that much more important to find the most effective ways of managing and treating diabetes.

 Resistance Training 

The study was conducted in order to evaluate how efficient specifically high-intensity, low volume resistance training, as a form of exercise, is in improving glycemic control.

There has been plenty of evidence proving that aerobic type exercise  and lower-intensity resistance training   types are effective in improving glycemic control. The modality in which resistance training works in improving glycemic control is known however there is a lack of high-intensity, low volume type exercise being studied in the literature to prove exactly how effective it is in improving glycemic control.

Where is the Research From?
This study was performed by C. Castaneda who is a recipient of a Brookdale National Fellowship and an International Life Sciences Institute Future Leader Award. The study took place in 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. It was also published in Diabetes care a peer reviewed journal. All these factors add to the reputability of the study.

What Type of Research Was This?
This was a randomised control trial consisting of 62 latino-americans over 55 years of age (M=66), whom had all been clinically diagnosed with type-2 diabetes for 3 year or more. They were randomly assigned to either a group that performed 16 weeks of high-intensity, low volume resistance training that got progressively harder over the 16 weeks (intervention group) or the control group which continued with their regular medical care from their personal doctor and were not given any dietary or exercise advice.

The intervention group exercised 3 times per week supervised at the HNRCA.

•	Each session was 45min in length, consisting of 5mins warm-up (six chair stands and a 1-min brisk walk around the exercise facility), 35mins using 5 pneumatic resistance machines (chest and leg press, upper back, knee extension, and flexion) and 5mins cool down (stretching and flexibility).

•	The participants performed 3 sets of 8 reps on each exercise per session

•	Intensity week 1-8 was 60-80% of baseline 1rm, 1rm was then retested after week 8, and intensity increased to 70-80% of week 8 1rm from week 10-14.

•	Participants were given 2 “easy” weeks at week 9 and 15 in order to minimize over-training related injury risk. These weeks were performed at 10% reduced intensity.

Glycemic control via plasma glycosylated hemoglobin levels, metabolic syndrome abnormalities such as blood pressure and blood triglycerides etc, composition, muscle strength and muscle glycogen stores were determined before and after the intervention.

The fact that this was a randomized control study gives a very clear indication of the effectiveness of the intervention.The training intervention used is conducive with yielding most strength gains and is indeed an effective high-intensity, low volume protocol. However there is no mention of rest intervals or rest protocols, given this can heavily manipulate the results it seems an oversight by this study. The study does some great things such as measuring associated risk factors of diabetes such as blood pressure, blood triglycerides, HDL and LDL levels as well as trunk fat (central adiposity). They could have potentially gone further into how effective the intervention was by measuring C-reactive protein, interleukin 6 and heat shock proteins.

Results
The study found that :

•	Plasma glycosylated hemoglobin levels (measure of glycemic control) were decreased after the 16 week intervention. This is compared with the control group who showed no change in glycemic control.

•	A 31% increase in muscle glycogen stores were observed as a result of the resistance training intervention opposed to the control group who inversely showed a 23% decrease in muscle glycogen stores.

•	 The intervention group also experienced an increase in lean mass and decreases in systolic blood pressure and trunk fat mass.

•	72% of the intervention group also reduced the dose of medication prescribed needed to manage their diabetes compared to the 42% of the control group who increased their prescription medications for diabetes.

Potentially one of the most overlooked results of the intervention was the increase in spontaneous physical activity. The incidental change in habitual physical activity and more active lifestyle is potentially the most positive long-term benefit of the exercise intervention.

Conclusion/Discussion
The study overall was very thorough and well conducted. The RCT showed that the intervention when directly compared to the control was definitely effective in improving glycemic control.

Ultimately the study tried to use the latino-american group to represent a minority with inadequate access to substandard health care. Groups such as these are in desperate need of lifestyle and exercise interventions to manage and treat their diabetes. The cost of medical care associated with diabetic related as well as the cost of diabetes medications is ever increasing. Therefore by finding cost friendly alternatives to manage diabetes is ideal for these population groups. Although this group is a good representation of a high-risk group for diabetes, it is a very specific population and may not represent broader effectiveness of the intervention on a broader population.

The study also only uses a very small sample size of 62 which limits the conclusions we can draw as a result of the study.

The study also doesn’t compare exercise types. Aerobic exercise is shown to be more effective than resistance type training and even more effective is a combination of resistance and aerobic exercises. Whilst this study excellent at proving improved glycemic control through high-intensity resistance training there are better interventions out there that are not represented or acknowledged in this study.