Exercise as it relates to Disease/The effects of exercise on glycemic control in patients with Type 2 diabetes

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This research study ‘ Effects of Aerobic Training, Resistance Training, or Both on Glycemic Control in Type 2 Diabetes by Ronald J. Sigal, MD, MPH; Glen P. Kenny, PhD; Normand G. Boulé, PhD; George A. Wells, PhD; Denis Prud'homme, MD, MSc; Michelle Fortier, PhD; Robert D. Reid, PhD, MBA; Heather Tulloch, MSc; Douglas Coyle, PhD; Penny Phillips, MA; Alison Jennings, MA; James Jaffey, MSc, is a randomized control trial that will be further critiqued in this Wiki.

What is the background to this research?[edit]

Diabetes is a condition that affects the body’s ability to respond to insulin, leading to abnormalities revolving carbohydrate metabolism[1]. Due to this, diabetes heavily affects the body’s ability to monitor blood glucose levels, therefore glycemic control must be monitored to prevent health risks. Glycemic control is defined as the regulation and maintenance of blood glucose levels in the body. Glycemic control is assessed by haemoglobin A1c levels (HbA1c), which are responsible for monitoring blood glucose levels[2]. Research suggests that poor glycemic control can lead to cardiovascular risks such as heart failure and myocardial infarction. Other health related risks include:

  • Cardiovascular disease
  • Kidney damage
  • Nerve damage
  • Damage blood vessels

Evidence has suggested that exercise is a viable option for improving glycemic control for patients with type 2 diabetes[3]. In particularly, aerobic training, resistance training and the combination of both. It can be said that monitoring blood glucose levels is important to prevent further health related risks amongst patients diagnosed with type 2 diabetes[4].

Where is the research from?[edit]

The research was conducted by various professions and institutions including the University of Ottawa, Clinical Epidemiology Program, Ottawa Health Research Institute, and Prevention and Rehabilitation Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada, and University of Calgary, Calgary, Alberta, Canada[5].

What kind of research was this?[edit]

  • The research was conducted as a randomized, control trial that was performed over 26-week time period
  • The evidence behind a randomized control trial reduces bias throughout the study as well as preventing skewed or deliberate manipulation of results
  • Participants were randomly placed in either a control group, aerobic training, resistance training or combined group (both aerobic and resistance training)

What did the research involve?[edit]

251 participants aged between 39 to 70 years old with type 2 diabetes underwent a randomized control trial. Each participant was placed in either a control group, aerobic training group, resistance training group or the combination of both types of training, to determine the effects of exercise on improving glycemic control. The study was conducted over a 26-week period to mitigate the effects of exercise on Haemoglobin A1c levels. The first 4 weeks of the study consisted of a run-in phase. The aim of the run-in phase was to allow the body to gradually adapt to incoming stimulus whilst preventing muscle soreness and injury. Aerobic training was performed a cycle ergometer or treadmill at 50% maximum oxygen consumption with the use of polar oy heart monitors to reach the desired intensity. Intensity and duration were increased on a weekly basis to allow for progression and further training adaptations. The resistance training method involved participants to perform a resistance training regimen that outline specific exercises, repetitions and sets. This training regimen was modified to ensure that progressive overload was being achieved. The combined group performed both aerobic and resistance training sessions as one big training session.

Limitations of the study show that the combined group (aerobic and resistance training) had a longer duration of training time when compared to the aerobic and resistance groups.

What were the basic results?[edit]

Results of the study indicated that glycemic control was improved through aerobic and resistance training alone, as well as the combination of the two training methods. The findings of the research displayed that all training methods resulted in decreased haemoglobin A1c levels, therefore improving glycemic control. Aerobic activity showed a decrease of HbA1c levels from 7.41% to 6.98%. For optimal glycemic control, evidence indicate the maintenance of 7% or below in HbA1c is efficient for older patients with type 2 diabetes[6].

Results displayed that resistance training was effective in decreasing haemoglobin A1c levels. Over a 6-month period, haemoglobin A1c showed a decreased of 7.48% to 7.18%. In addition to this, the effect of resistance training improved body composition through fat loss and improved muscular endurance.

The main finding of the study was concluded through the results of the combined training on HbA1c. Over a 6-month period, participants HbA1c dropped from 7.46 to 6.56 (0.9%). This figure represents that the combined trial group was the most effective in terms of improving glycemic control in patients with type 2 diabetes.

What conclusions can we take from this research?[edit]

The findings of the research concluded that either aerobic training, resistance training or the combination of both, reduced haemoglobin A1C levels. The study suggests that the combination of aerobic and resistance training on a weekly basis (at least 3 times per week) is optimal for improving glycemic control when compared to aerobic and resistance training alone. The findings of this study conclude that haemoglobin A1c levels were significantly decreased in the combined training group, indicating that a combination of aerobic and resistance training is most appropriate method for improving glycemic control. When compared to other similar studies, this study concludes that the idea of combined training is most beneficial when performed in the combination of both aerobic training at 50% maximum oxygen consumption and high intensity resistance training[7].

Conclusion of this study also suggests that performing exercises on a weekly basis is directly linked to changes in body composition, by decreasing fat loss and increasing muscular endurance.

Practical advice[edit]

  • Engage in the combination of both aerobic and resistance training to maximise the effect of exercise on haemoglobin A1c levels
  • It is recommended that individuals engage in either aerobic or resistance training (or both) at least 3 times per week
  • When performing aerobic sessions, it is recommended that individuals perform aerobic activities at 50% of maximum oxygen capacity to optimise results
  • To ensure optimal results through resistance training, make sure that high intensity is maintained throughout each training session
  • Perform resistance exercises from repetition ranges of 6-12 to allow for hypertrophy and muscle growth
  • Implement various resistance exercises every 4 weeks to allow for new stimulus to shock the muscles
  • To reduce the risk of injury, ensure that warm-up and cooldown protocols are included

Further information/resources[edit]

Further information regarding the management of glycemic control and type 2 diabetes can be found below:

Journal Articles:

References[edit]

  1. Diabetesaustralia.com.au. (2019). What is diabetes?. [online] Available at: https://www.diabetesaustralia.com.au/what-is-diabetes.
  2. Church TS, Blair SN, Cocreham S, Johannsen N, Johnson W, Kramer K, et al. Effects of aerobic and resistance training on hemoglobin A1c levels in patients with type 2 diabetes: a randomized controlled trial. 2010;304(20):2253-62.
  3. Norris SL, Lau J, Smith SJ, Schmid CH, Engelgau MMJDc. Self-management education for adults with type 2 diabetes: a meta-analysis of the effect on glycemic control. 2002;25(7):1159-71.
  4. Castaneda C, Layne JE, Munoz-Orians L, Gordon PL, Walsmith J, Foldvari M, et al. A randomized controlled trial of resistance exercise training to improve glycemic control in older adults with type 2 diabetes. 2002;25(12):2335-41.
  5. Sigal RJ, Kenny GP, Boulé NG, Wells GA, Prud'homme D, Fortier M, et al. Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: a randomized trial. 2007;147(6):357-69.
  6. Albright A, Franz M, Hornsby G, Kriska A, Marrero D, Ullrich I, et al. American College of Sports Medicine position stand. Exercise and type 2 diabetes. 2000;32(7):1345-60.
  7. Dunstan DW, Daly RM, Owen N, Jolley D, De Courten M, Shaw J, et al. High-intensity resistance training improves glycemic control in older patients with type 2 diabetes. 2002;25(10):1729-36.