BACKGROUND: Interleukin-15 (IL-15), a well-known myokine, is highly expressed in skeletal muscle and is involved in muscle-fat crosstalk. Recently, a role of skeletal muscle-derived IL-15 in the improvement of glucose homeostasis and insulin sensitivity has been proposed. However, little is known regarding the influence of endurance training on IL-15 expression in type 2 diabetic skeletal muscles. We investigated the effect of endurance exercise training on glucose tolerance and IL-15 expression in skeletal muscles using type 2 diabetic animal models. METHODS: Male Zucker diabetic fatty (ZDF) and ZDF lean control (ZLC) rats were randomly divided into three groups: sedentary ZLC, sedentary ZDF (ZDF-Con), and exercised ZDF (ZDF-Ex). The ZDF-Ex rats were forced to run a motor-driven treadmill for 60 minutes once a day 5 times per week for 12 weeks. Intraperitoneal glucose tolerance test (IPGTT) was performed after 12 weeks. Expression of IL-15 was measured using ELISA in extracted soleus (SOL) and gastrocnemius medial muscles. RESULTS: After 12 weeks of treadmill training, reduction of body weight was observed in ZDF-Ex compared to ZDF-Con rats. Glucose tolerance using IPGTT in diabetic rats was significantly improved in ZDF-Ex rats. Furthermore, the expression of IL-15 was significantly increased (P<0.01) only in the SOL of ZDF-Ex rats compared to ZDF-Con. Additionally, IL-15 expression in SOL muscles was negatively correlated with change of body weight (R=-0.424, P=0.04). CONCLUSION: The present study results suggest that 12 weeks of progressive endurance training significantly improved glucose tolerance with concomitant increase of IL-15 expression in SOL muscles of type 2 diabetic rats.
Animals ; Body Weight ; Enzyme-Linked Immunosorbent Assay ; Glucose Intolerance* ; Glucose Tolerance Test ; Homeostasis ; Insulin Resistance ; Interleukin-15* ; Male ; Muscle, Skeletal ; Muscles ; Rats ; Rats, Zucker*

BACKGROUND: Interleukin-15 (IL-15), a well-known myokine, is highly expressed in skeletal muscle and is involved in muscle-fat crosstalk. Recently, a role of skeletal muscle-derived IL-15 in the improvement of glucose homeostasis and insulin sensitivity has been proposed. However, little is known regarding the influence of endurance training on IL-15 expression in type 2 diabetic skeletal muscles. We investigated the effect of endurance exercise training on glucose tolerance and IL-15 expression in skeletal muscles using type 2 diabetic animal models. METHODS: Male Zucker diabetic fatty (ZDF) and ZDF lean control (ZLC) rats were randomly divided into three groups: sedentary ZLC, sedentary ZDF (ZDF-Con), and exercised ZDF (ZDF-Ex). The ZDF-Ex rats were forced to run a motor-driven treadmill for 60 minutes once a day 5 times per week for 12 weeks. Intraperitoneal glucose tolerance test (IPGTT) was performed after 12 weeks. Expression of IL-15 was measured using ELISA in extracted soleus (SOL) and gastrocnemius medial muscles. RESULTS: After 12 weeks of treadmill training, reduction of body weight was observed in ZDF-Ex compared to ZDF-Con rats. Glucose tolerance using IPGTT in diabetic rats was significantly improved in ZDF-Ex rats. Furthermore, the expression of IL-15 was significantly increased (P<0.01) only in the SOL of ZDF-Ex rats compared to ZDF-Con. Additionally, IL-15 expression in SOL muscles was negatively correlated with change of body weight (R=-0.424, P=0.04). CONCLUSION: The present study results suggest that 12 weeks of progressive endurance training significantly improved glucose tolerance with concomitant increase of IL-15 expression in SOL muscles of type 2 diabetic rats.
Animals ; Body Weight ; Enzyme-Linked Immunosorbent Assay ; Glucose Intolerance* ; Glucose Tolerance Test ; Homeostasis ; Insulin Resistance ; Interleukin-15* ; Male ; Muscle, Skeletal ; Muscles ; Rats ; Rats, Zucker*

BACKGROUND: We investigated the therapeutic effects of resistance training on Zucker rats before and after the onset of diabetes to understand the importance of the timing of exercise intervention. We assessed whether 8 weeks of resistance training ameliorated impaired glucose tolerance and altered muscle fiber type composition in Zucker rats. METHODS: Five-week-old male Zucker rats were divided into Zucker lean control (ZLC-Con), non-exercised Zucker diabetic fatty (ZDF-Con), and exercised Zucker diabetic fatty (ZDF-Ex) groups. The ZDF-Ex rats climbed a ladder three times a week for 8 weeks. Intraperitoneal glucose tolerance tests (IPGTT) were performed on the 1st and 8th weeks of training, and grip strength was measured during the last week. We also measured glucose transporter 4 (GLUT4) expression by Western blot and immunofluorescence. Moreover, immunohistochemistry was performed to assess muscle fiber type composition. RESULTS: Fasting glucose levels and area under the curve responses to IPGTTs gradually increased as diabetes progressed in the ZDF-Con rats but decreased in the ZDF-Ex rats. Grip strength decreased in the ZDF-Con rats. However, resistance training did not improve grip strength in the ZDF-Ex rats. GLUT4 expression in the ZLC-Con and the ZDF-Con rats did not differ, but it increased in the ZDF-Ex rats. The proportions of myosin heavy chain I and II were lower and higher, respectively, in the ZDF-Con rats compared to the ZLC-Con rats. Muscle fiber type composition did not change in the ZDF-Ex rats. CONCLUSION: Our results suggest that regular resistance training initiated at the onset of diabetes can improve glucose tolerance and GLUT4 expression without changing muscle morphology in Zucker rats.
Animals ; Blotting, Western ; Diabetes Mellitus, Type 2 ; Fasting ; Fluorescent Antibody Technique ; Glucose Tolerance Test ; Glucose Transport Proteins, Facilitative ; Glucose* ; Hand Strength ; Humans ; Immunohistochemistry ; Male ; Myosin Heavy Chains ; Rats ; Rats, Zucker* ; Resistance Training*

Sarcopenia is a major component of age-related frailty and also a strong predictor of disability, morbidity, and mortality in the aging population. Resistance exercise could be the most effective intervention that improves muscle mass, muscle strength, and physical performance, thus preventing sarcopenia in older adults. The benefits of these exercise programs correlate with the intensity and the frequency of the exercise regimes used in the trials. Clinical trials vary in terms of population, setting, and exercise regimes; hence, more standardized clinical trials are required. In this review, we focus on the effects of resistance exercise on muscle mass, strength, cognitive and physical function, and the principle and applications of resistance exercise considering recent trends that include high-intensity interval training, high speed power training, eccentric exercise, and whole-body vibration exercise.
Adult ; Aged ; Aging ; Frail Elderly ; Humans ; Mortality ; Muscle Strength ; Sarcopenia* ; Vibration

BACKGROUND: Aging related decrease in muscle strength and flexibility leads to functional loss of physical ability. Power training is known to improve these capacities and helps in performing daily routine better. Therefore, we modified previously proven and certified sarcopenia intervention exercise for elderly in rural community and applied them to examine the effects on physical fitness and muscle functions to show its applicability. METHODS: Subjects were divided into control and exercise group using single-blind method. Exercise group underwent high-speed elastic band training(concentric contraction in 1 second) 2 days per week for 12 weeks. Before and after the intervention, we performed body composition analysis, anthropometric measurement, blood test, blood pressure check, senior fitness test (SFT), upper body and lower body strength examination. Korean version of Physical Activity Scale for the Elderly (K-PASE), and Center for Epidemiological Studies- Depression Scale (CES-D) were also assessed. RESULTS: Body weight in control group was significantly increased (Paired t-test: P=0.008), although it was consistent in exercise group (GroupxTime: P=0.013). 30-second chair stand (P<0.001) and 30-second arm curl (P<0.001) of the senior fitness test were also significantly improved in exercise group compared to control. In addition, muscle strength of knee flexion (P=0.034) and K-PASE score (P<0.001) were improved in training group with statistical significance. CONCLUSIONS: The modified high-speed elastic band training for rural elderly improved muscle strength and daily physical performance. This result suggests a simple and easy to perform band training could be an excellent solution to prevent sarcopenia in rural elderly. It also supports the evidence that this program would be widely distributed.
Aged* ; Aging ; Arm ; Blood Pressure ; Body Composition ; Body Weight ; Depression ; Hematologic Tests ; Humans ; Knee ; Motor Activity ; Muscle Strength ; Physical Fitness* ; Pliability ; Rural Population ; Sarcopenia ; Single-Blind Method