Impact of Exercise on Patients with Diabetes Mellitus Bret Goodpaster, Ph.D. Exercise Physiologist Professor of Medicine University of Pittsburgh Division of Endocrinology and Metabolism Learning Objectives After completing this section, students should be able to: Define physical activity and physical fitness Recommend appropriate evaluation for patients who wish to start an exercise program Prescribe appropriate general exercise program guidelines for type, intensity, duration and frequency of exercise Compare the benefits of aerobic and resistance training exercise Discuss precautions and contraindications for aerobic and resistance training Compare and contrast guidelines for exercise prescription by various professional societies Definitions: Physical Activity and Health Physical Activity - any body movement that is produced by contraction of skeletal muscle that requires energy in excess of resting energy expenditure Exercise a subset of physical activity; planned, structured and repetitive bodily movement performed to improve or maintain components of physical fitness Physical Fitness Cardiorespiratory Fitness the ability of circulatory and respiratory systems to supply oxygen during sustained movement Gold standard of measurement: VO 2 max test MET (Metabolic equivalent) a unit of intensity equal to energy expenditure at rest Muscular Fitness refers to strength and muscular endurance Flexibility the range of motion available at the joints Aerobic Exercise Consists of rhythmic, repeated and continuous movement of large muscle groups Jogging/walking Continuous swimming Many sports Increases cardiorespiratory fitness Anaerobic Exercise Resistance/Strength training activities that use muscular strength to move a weight or work against a resistance load Weightlifting with free weights Exercises using weight machines Exercises using own body weight (e.g., push ups) Increases muscular fitness 1
Evaluation of Patients with Diabetes Before Recommending an Exercise Program The patient s age and previous physical activity level should be considered Evaluate glycemic control May need to modify meds or CHO ingestion prior to exercise Contraindications to exercise CVD Severe peripheral neuropathy Severe autonomic neuropathy Retinopathy ADA Guidelines Suggested that before beginning a vigorous or moderate exercise program, an exercise ECG stress test should be done in all individuals with diabetes aged >35 years and in all aged >25 yrs. in the presence of even one additional CVD risk factor Exercise Precautions Recommend CV exam (ACSM stratification) Impaired response (HR and BP) - autonomic neuropathy VO 2 max may be 15-20 decreased Some HTN during exercise Post exercise hypotension Alternative modalities due to neuropathy, etc. Exercise Precautions Careful foot evaluation Eye Exam Cardiovascular exam Carry ID Carry source of CHO: candy? Have plenty of fluids available Long, slow warm up Monitor blood glucose Exercise with a partner May use RPE scale Initial Supervision Exercise Prescription FITT Principle Frequency Intensity Time (duration) Type Frequency Type 1 DM suggested to perform exercise daily Type 2 DM suggested to exercise 3-5 days per week 2
Intensity Heart Rate Intensity of exercise can be measured in many ways: Heart Rate % VO 2Max (aerobic capacity) Rate of Perceived Exertion (RPE) Heart rate (HR) is one of the most common ways to prescribe exercise Target heart ranges are given to individuals to make sure they get a good benefit from their exercise session HR max can be directly measured during an exercise stress test or can be calculated Learning Activity: Estimate Maximal Heart Rate and Calculate Target Exercise Heart Rate Ranges Heart Rate max: 220 - age = HR max ± 12 bpm Target Heart Rate Range = 60%- 80%: 220 - age = HR max HRmax x.60 = 60% of HR max HRmax x.80 = 80% of HR max Practice Calculations HR max and Target HR Ranges: 60-year-old Individual Heart Rate max: 220 - age = HR max ± 12 bpm 220-60 = 160bpm Target Heart Rate Range = 60%- 80%: 220 - age = HR max HRmax x.60 = 60% of HR max 160 x.60 = 96 bpm HRmax x.80 = 80% of HR max 160 x.80 = 128bpm Rate of Perceived Exertion (RPE) RPE is use very commonly when prescribing exercise RPE was developed by Borg on a 6-20 scale and now has been modified to a 1-10 scale as well RPE scale Asks the person, How hard do you feel that you are exercising? Due to the fact that many individuals with diabetes are on beta blockers or have autonomic neuropathy their HR is blunted therefore Target HR ranges do not work well Rate of Perceived Exertion: RPE Scale RPE SCALE 6 7 Very, very light 8 9 Very light 10 11 Fairly light 12 13 Somewhat hard 14 15 Hard 16 17 Very hard 18 19 Very, very hard 20 3
Rate of Perceived Exertion: RPE Scale 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Very Very Fairly Moderate Hard Very Very Very Light Light Hard Very Light Hard Examples: Intensity Moderate Intensity RPE Scale 13-15 (somewhat hard hard range) 40-80% VO 2max I m not working hard at all. I can talk and even sing easily. and breathing a little harder than usual. I can still talk easily. and breathing somewhat hard. I can talk fairly easily. Stay in this range hard and breathing deeply. I can still talk. very hard. I can t catch my breath or talk. 40-75 % HR max Why Moderate Intensity? Time (Duration) Unlikely to injure oneself Easy to plan into schedule Moderate exercise gives the same health benefit as hard exercise At early stages start individual out at 10-15 minutes of continuous exercise Gradually increase to 30 minutes of exercise Most position statements suggest between 20-60 minutes of exercise Intermittent bouts of exercise can be performed (bouts of 10 minutes) Time (Duration) Type of Exercise Type 1 DM: Duration 20-30 minutes (more than 30 minutes and insulin requirements drop dramatically) Type 2 DM: 20-60 minutes (maximizes caloric expenditure) Aerobic Exercise Resistance Exercise 4
Getting Started with Exercise Start out Slow and go at a Low intensity Gradually build up from 10-15 minutes of exercise Recommendations: Aerobic Exercise To improve glycemic control, assist with weight maintenance and reduce CVD at least 150 min/ week of moderate intensity and/or at least 90 minutes of vigorous aerobic exercise. At least three days a week. (Boule et al., Hollosky et al., Boule et al.) Performing 4 h/week of moderate to vigorous aerobic and/or resistance exercise is associated with greater CVD risk reduction. (Wei et al, Hu et al.) For long-term maintenance of major weight loss (30 lbs.), larger volumes of exercise 7h/week may be helpful. ( Klem et al., Pavlou et al, Scheller et al., Weinsier et al., Saris et al.,) Resistance Exercise Increases muscle mass and endurance Often causes more rapid changes in functional status and body composition than aerobic exercise Improves insulin sensitivity to about the same extent as aerobic exercise (Ivy, 1997) During the last 10-15 years ACSM and others have recommend resistance training be included in fitness programs for healthy, elderly, middle aged, older adults and individuals with diabetes Absolute Contraindications to Strength Training Unstable angina Uncontrolled hypertension Uncontrolled arrhythmias Hypertrophic cardiomyopathy Certain stages of retinopathy Relative Contraindications to Strength Training Congestive Heart Failure Myocardium ischemia Poor left ventricular function Autonomic neuropathies Safety of Resistance Exercise Before beginning a resistance program, it is essential that the individual knows what joint and muscles they are exercising Try exercise without any weights prior Never use other joints and muscles to cheat in order to complete a lift Use full range of motion when lifting 5
Safety of Resistance Exercise Warm up the muscles Never lock a joint during an exercise Do not hold your breath when lifting Breathing is important to avoid dangerous increases in blood pressure or pressure behind the eyes Exhale on the effort Allow muscle to recover between sets and never exercise the same muscle groups two days in a row Recommendations: Resistance Exercise In absence of contraindications, individuals with diabetes should be encouraged to perform resistance exercise Include all major muscle groups Progress slowly to three sets of 8-15 repetitions as a weight can be lifted more than 8-15 times ExRx: Type 1 DM ExRx: Type 2 DM Daily Exercise or Activity Duration 20-30 minutes (more than 30 minutes and insulin requirements can drop dramatically) Insulin: 1-2 units by MD; CHO 10-15 mg pre 30 minutes of exercise; inject into nonactive sites; avoid during insulin peaks Mode: Low-impact aerobic and resistance Intensity: 40-80% HR max Frequency: 3-5 days per week Duration: 20-60 minutes(calories) Maximize Caloric Expenditure Use of RPE for monitoring (HR affected by neuro.) The Positions of Major Professional Associations on Recommended Types and Amounts of Resistance Training The Positions of Major Professional Associations on Recommended Types and Amounts of Resistance Training Reference Frequency No. of exercises Sets/ repetitions Reference Frequency No. of exercises Sets/ repetitions Healthy adults: 1996 US Surgeon General s Report Healthy Adults: 2000 ACSM Position Stand 2 days 8-10 exercises involving major muscle groups 2 days/week 8-10 exercises involving major muscle groups 1-2 sets, 8-12 reps 1 set, 8-12 reps Elderly People: 1998 ACSM Position Stand Type 2 DM: 2000 ACSM Position Stand Type 2 DM: ADA 2002 Guidelines 2 days/week 8-10 exercises involving major muscle groups At least 2 days a week High resistance exercise using weights may be acceptable for young individuals Minimum of 8-10 exercises involving major muscle groups Or those with longstanding diabetes. Moderate weight training that use light weights and 1 set, 10-15 reps Minimum of 1 set, 10-15 reps High reps. Can be used for maintaining or enhancing upper body strength in nearly all patients with diabetes 6
Exercise Risks Recommended Readings Hypoglycemia (immediate, 4-6 hours after, 24 later) Worsening of hyperglycemia (ketoacidosis) Cardiovascular accidents Degenerative joint disease (mostly with high volume running) Microvascular damage: eyes, kidneys Orthopedic injury or ulcer: feet Medicine & Science in Sports & Exercise: Exercise and Type 2 Diabetes: American College of Sports Medicine and the American Diabetes Association: Joint Position Statement December 2010 - Volume 42 - Issue 12 - pp 2282-2303 Devlin J, Scheider S, Kriska A: Handbook in exercise in diabetes. Ruderman N, Ed. Alexandria, VA, American Diabetes Association, 2002 Sigal RJ, Kenny GP, Wasserman DH, Castaneda- Sceppa C: Physical activity/exercise and type 2 diabetes. Diabetes Care 27:2518-2539, 2004 7