Hai-guo LIU, Guo-zheng LI

The therapeutic eff ect of aerobic exercise with resistance training in elderly men with type 2 diabetes mellitus

Hai-guo LIU1, Guo-zheng LI2

1. Sports Department of Xi’an University of Sport, Xi’an 710068, China;
2. Graduate School of Xi’an University of Sport, Xi’an 710068, China

Objecti ve:This study was conducted to examine the eff ects of aerobic exercise alone and aerobic exercise with resistance training on the quality of life in men over the age of 55 years with type 2 diabetes mellitus.Methods:A total of 54 participants were divided into the following three groups so that there were no signifi cant diff erences in blood chemistry or physical ability indexes among the three groups: control, aerobic exercise, and aerobic exercise with resistance training. The latt er two groups exercised for 24 weeks, while the control group performed no exercise. Blood chemistry levels and measures of physical ability in each group members were examined one day before and one day aft er the exercise regimens.Results:Compared with those before the study, blood glucose, glycated hemoglobin, triglycerides, cholesterol, and low-density lipoprotein levels as well as vital capacity, reacti on ti me, sit-and-reach ability, and balancing while standing on one leg with closed eyes were signifi cantly improved in the aerobic exercise only group (P < 0.05). All these measures as well as high-density lipoprotein levels and grip, back, and leg strength were signifi cantly improved in the combined aerobic and resistance training group (P < 0.05). By contrast, no signifi cant diff erences before and aft er the experiment were found in any measure for the control group (P > 0.05).Conclusion:Although both aerobic exercise and aerobic exercise combined with resistance training for 24 weeks eff ecti vely improved the quality of life in pati ents with type 2 diabetes, the eff ect of the combined training was bett er than that of aerobic exercise alone. These results suggest that resistance training may be safely added to the rehabilitati on training regimen of pati ents with type 2 diabetes mellitus.

type 2 diabetes mellitus; aerobic exercise; aerobic exercise with resistance training; quality of life

Introduction

Type II diabetes, once known as noninsulindependent diabetes mellitus, is characterized by insulin resistance and compensatory hyperinsulinemia. Type II diabetes can be initially developed by insulin resistance to impaired glucose metabolism and ultimately leads to significant hyperglycemia [1-2]. Exercise therapy, especially aerobic exercise, has been regarded as an effective way to treat diabetes and had been widely used in the rehabilitation of patients with diabetes. However, rehabilitation through an aerobic exercise regimen can be limited due to low patient compliance, with patients reporting that it requires a lot of their time and becomes boring. Additionally, studies have found that the altered energy metabolism induced by aerobic exercise improves blood glucose levels in patients with diabetes only to a limited degree. However, we postulated that adding resistance training to aerobic exercise will not only reduce the time required for aerobic exercise therapy during each workout in patients with diabetes but may also provide greater therapeutic value. Therefore, the present study examined the effect of long-term aerobic exercise with resistance training on the quality of life in elderly men with type 2 diabetes mellitus.

Materials and Methods

Ethics statement

All 70 elderly men initially recruited for this study understood the experimental objective, volunteered to join the study, and signed an informed consent form. The experiment was approved by the local ethics committee at the University of Sport, Xi’an, China.

Inclusion criteria and participant groups

Th e inclusion criteria were as follows: (1) men aged more than 55 years, with fasting blood glucose levels above 7 mmol/L and no serious complications of diabetes; (2) no systematic exercise or training history but could bear a certain movement load; (3) an education level of at least junior high school; (4) a basic ability to, see, hear, communicate, and take care of themselves; (5) the capacity to complete the questionnaire and tests according to the quantity and quality requirements as discussed below.

The participants were divided into the following three groups based on their blood glucose and blood lipid levels and other indexes to ensure no signifi cant diff erences in these values among these groups: control, aerobic exercise, and aerobic exercise with resistance training.

Exercise regimens for each group

Men in the control group maintained their normal living habits, including their diet, sugar intake, and lipid-reducing drugs and did not participate in any sports for the duration of the experiment.

Men in the aerobic exercise group performed traditional aerobic exercises, such as brisk walking or Taijiquan, four times per week for 24 weeks. Each exercise session lasted 60 to 80 minutes, with a target heart rate between 70% and 80% of their maximum heart rate, as determined by subtracting their age from 220 (e.g., heart rate was controlled between 120–140 beats/min). The exercise sessions were guided by a professional trainer and generally took place from 7:00 to 8:20 h or 15:30 to 16:50 h. Heart rate was monitored in real-time to ensure target heart rates throughout the exercise period.

Men in the aerobic exercise with resistance training group performed the same aerobic exercise as that in the aerobic exercise group, with each session lasting at least 30 min. This group also participated in progressive resistance training using TheraBand resistance bands aft er their aerobic exercise training four times a week for 24 weeks. Under the guidance of professional sports staff, who also ensured sufficient warm-up and cool-down stretching exercises, the men performed multi-angle stretch training, which included six movements for the upper and six for the lower limbs. The exercise intensity was preset as 55% to 65% 1RM of the target muscle group. Each movement was repeated 6–8 times, followed by a 2-min break before a second set was performed.

Trained medical personnel supervised conventional drug treatments (including hypoglycemic, stepdown, and lipid-lowering drugs) and diet restrictions for men in both aerobic exercise groups.

Measurements

Blood glucose, glycosylated hemoglobin, triglycerides, cholesterol, high-density lipoprotein, and low-density lipoprotein were measured with an automatic biochemical analyzer (Healife, China) when participants were in a fasting state every morning. Physical quality indexes were also recorded, including heart rate, vital capacity, reaction time, ability to sit and reach, balancing while standing on one leg with closed eyes, and grip, back, and leg strength. Each index was examined one day before and one day aft er the 24-week exercise program.

Statistical analysis

Th e recorded data were analyzed with the statistical software package SPSS 17.0 and Microsoft Excel 2007. The results are expressed as the mean ± standard deviation. The statistical significance of the difference in each index measured before and after the experiment was determined using paired sample t-tests, with P < 0.05 considered statistically signifi cant.

Results

A total of 54 men with type 2 diabetes mellitus met the inclusion requirements and were thus included in this study. Th e number of participants in each group was 17 for control, 16 for aerobic exercise, and 14 for aerobic exercise with resistance training.

Blood chemistry indexes

No data were missing for the blood chemistry analysis. Table 1 shows the levels of blood glucose, glycated hemoglobin, triglycerides, cholesterol,highdensity lipop-rotein, and low-density lipoprotein for all participants in the three groups one day before and one day aft er participating in 24 weeks of exercise.

We found that blood chemistry indexes in participants after exercise training were improved. Compared with those before the experiment, blood glucose, glycosylated hemoglobin, cholesterol, and low-density lipoprotein levels of participants in the aerobic exercise group were significantly different aft er training (P<0.05). All blood indexes measured in participants assigned to the aerobic exercise with resistance training group were signifi cantly diff erent aft er training (P<0.05), whereas none was signifi cantly diff erent in the control group (P>0.05).

Physical quality indexes

Th e results in Table 2 show that 24 weeks of exercise training improved participants’ physical quality indexes. Vital capacity, reaction time, sit-and-reach ability for participants in the aerobic exercise group were significantly different after training compared with these indexes before training (P<0.05). All physical quality indexes, except heart rate, were significantly different in the aerobic exercise with resistance training group (P<0.05), whereas no indexes of physical quality were statistically diff erent before and aft er the experiment in the control group (P>0.05).

Discussion

Diabetes, a metabolic disease caused by a defect in insulin secretion that leads to continuous high blood glucose, seriously endangers human health. Exercise is currently one effective treatment, and its crucial role has not been replaced by any traditional drug therapy. A large number of studies have confirmed that long-term regular aerobic exercise can effectively improve blood glucose and blood lipid levels in patients with diabetes, and it has a positive eff ect on the quality of life in patients with diabetes. Fei et al. found that regular aerobic exercise for 12 weeks significantly lowers levels of blood glucose, triglycerides, cholesterol, and lowdensity lipoprotein in patients with diabetes mellitus, suggesting that it is an important adjunct therapy [3]. Zhou and colleagues found that blood glucose and blood lipid levels and other indexes of diabetes aft er brisk walking exercise for 12 weeks show varying degrees of improvement while those for patients in the control group change little [4], consistent with the results reported by Zhang et al[5-6]. Th ese data indicate that regular aerobic exercise, with advantagesover drug therapy of expense, safety and ease of use, plays a positive role in improving the quality of life in patients with type 2 diabetes mellitus.

Tab. 1 Blood chemistry indexes before and after 24 weeks of exercise.

Tab. 2 Physical quality indexes before and after 24 weeks of exercise.

Additionally, some studies have found that combing aerobic exercise and resistance training provides a better quality of life for patients. Li found that both aerobic exercise and resistance training for 12 weeks improve blood chemistry indexes in type 2 diabetes, and compared with either aerobic or resistance exercise alone, the combined exercise shows better eff ects on adjusting blood glucose and body weight [7]. Lu and colleagues showed that aerobic exercise or resistance exercise for 3 months improves blood glucose and glycosylated hemoglobin in patients with diabetes, but the eff ects of the combined aerobic exercise and resistance training are better [8].

In the present study, the blood chemistry indexes in both exercise groups improved after 24 weeks of exercise. However, the changes in the combined aerobic and resistance training group indicated that the combined exercise more effi ciently improved the effect on blood glucose and blood lipid levels than aerobic exercise alone. It also signifi cantly increased high-density lipoprotein levels, while aerobic exercise alone did not. High-density lipoprotein, a vascular scavenger, acts as an anti-atherogenic lipoprotein in plasma and is a protective factor against coronary heart disease. It also helps prevent the occurrence of cardiovascular disease in the elderly.

In addition to having improved blood chemistry indexes, participants in this 24-week exercise study showed improved physical indexes. The indexes for men in the combined aerobic and resistance training were better than those in the other two groups, with muscle strength significantly improved only in the combined exercise group. Muscle strength has an important role in decreasing the occurrence of muscle pain in the elderly as well as in improving their exercise capacity.

Th e main mechanism whereby resistance training improved blood glucose and lipid levels and physical characteristics of patients with type 2 diabetes mellitus may be that long-term resistance training improved the morphological structure and physiological function of muscles, resulting in muscle fiber thickening and muscle strength increasing. Muscle strength and insulin resistance are negatively correlated. An increase in muscle strength makes the body more sensitive to insulin, promotes the expression of the glucose transporter gene, and accelerates cell intake of glucose, leading to a reduction in the body’s blood sugar [2]. Long-term resistance training can improve the ability of blood vessels to relax significantly, increase perfusion volume and reserve capacity of blood flow in blood vessels, improve the blood circulation rate in the body, and stimulate metabolism. For example, Beynard and colleagues found that resting forearm microcirculation and blood fl ow reserve capacity in participants are signifi cantly increased by performing long-term resistance training exercise [9].

In summary, both aerobic exercise and aerobic exercise with resistance training for 24 weeks improved the quality of life in patients with type 2 diabetes, as measured by blood chemistry and physical indexes. However, the eff ect of the combined exercise was better than that of aerobic exercise alone. Th ese results suggest that resistance training may be a safe and effective adjunct to rehabilitation regimens in patients with type 2 diabetes mellitus.

1. Kong SJ, Fu JH. Insulin resistance and glucose with lipid metabolism[J]. Chin J Gerontol, 2009, 29(18) : 2403-2405.

2. Xi X, Hu JP. Effect of exercise therapy for elderly patients with diabetes[J]. Chin J Gerontol, 2014, 34 (18): 5306-5308.

3. Fei JM, Liu ZM, Zhu H. Effect of regular physical activity on type 2 diabetes for elderly[J]. Chin J Appl Physiol, 2015, 31(1): 9-11.

4. Zhou HM, Li BY, Zhu H, et al. Effect of vigorous walk on elderly type 2 diabetes[J]. Chin J Appl Physiol, 2015, 31(3): 243-244, 248.

5. Chen WR, Chen J. Infl uence of Taijiquan and Qigong Ba Duan Jin for lipids and quality of life of elderly[J]. Chin J Gerontol, 2015, 35(10): 5612-5613.

6. Zhang WJ, Sun L. Effect of exercise on blood glucose and lipid levels in elderly diabetic patients[J]. Chin J Gerontol, 2012, 32(2): 389-390.

7. Li TX. Effect of different exercise interventions on blood biochemical indices of type 2 diabetes[J]. Sport Sci Shandong, 2014, 36(6): 81-84.

8. Lu LR, Dai X, Chen QY, et al. Effect of combined resistance-aerobic exercise on metabolism indices of pre-diabetes population[J]. J Guangxi Med Univ, 2016, 33(1): 57-59.

9. Baynard T, Miller WC, Fernhall B. Effects of exercise on vasodilatory capacity in endurance and resistance trained men[J]. Eur J Appl Physiol, 2003, 89 (1): 69-73.

doi 10.13459/j.cnki.cjap.2016.06.010

Hai-guo LIU, Master, Lecturer, Beilin block hanguang road, No 65, Xi’an 710068, China. Tel：18502992966 ; E-mail: 3504686722@qq.com.

2016-08-08; accepted 2016-10-08