As diabetes care and education specialists (DCESs), we utilize an array of effective strategies to manage and improve the health outcomes of people with diabetes (PWD). Although diet and aerobic exercise often take the spotlight in diabetes management plans, there is a highly effective but surprisingly underutilized tool in our arsenal: resistance exercise (RE).
Mentioning RE may bring to mind barbells and complicated gym routines, but this adaptable and patient-friendly activity has stark implications for health and wellness. It is essential that DCESs understand the benefits of RE, discuss the information, and feel confident in prescribing a basic RE program to PWD.
For an individual to get the best exercise benefit, it is important to include both aerobic exercise (AE) and RE in their routine. The joint statement of American College of Sports Medicine (ACSM) and the American Diabetes Association (ADA) states that a combination of AE and RE may be more effective in improving the amount of time that blood glucose levels are in target range than either alone; however, more studies are needed to determine if total caloric expenditure, exercise duration, or exercise mode is responsible.
The Centers for Disease Control and Prevention’s report, Physical Activity Among Adults Aged 18 and Over: United States, 2020, shows only 24% of US adults meet recommended levels of both AE and RE. Additionally, 7% engage exclusively in RE, summing up to only 31% of adults reaping the benefits of RE. On the other hand, 28% of US adults meet only the AE recommendation, and 46% fail to meet either recommendation. Particularly concerning is that PWD are typically less active than the general population.
Barriers to RE are varied. Cost, intimidation, and inconvenience are common reasons individuals have for not exercising. Hurley et al noted that perceived barriers to RE among collegeage women included a lack of time, a lack of desire, and the lack of self-discipline required to continuously take part in RE.
Senior adults, studied by Hurst et al, reported a general lack of awareness and understanding of RE. Most participants had never heard of the term “RE” and were unaware of its potential benefits. Interestingly, participants stated that they would be willing to try RE under expert guidance.
Individuals with diabetes who use exogenous insulin or oral secretagogues are often fearful of hypoglycemia and may avoid exercise altogether.
Motivational interviewing is a useful method to explore the patient’s ambivalence toward or lack of knowledge of RE. Once the reason or reasons are identified, DCESs can support the patient in developing a plan to incorporate RE into their daily routines.
AE involves rhythmic contractions of large muscle groups. Some examples are walking, cycling, swimming, and machines such as the elliptical and rower. These exercises burn calories in the presence of oxygen to generate energy.
RE involves working skeletal muscle against external resistance. RE requires short bursts of higher intensity. Glycolysis fuels RE, breaking down glucose in the absence of oxygen.
RE causes injury of the cellular proteins in the working muscles. The body repairs these microtears by adding amino acids (actin and myosin) to the myofilament, which causes them to hypertrophy (grow in size).
Dynamic and isometric exercises are the most common types of RE. Dynamic RE requires pushing or pulling against the weight of an object or moving body weight through a range of motion. Bicep curls or leg press are examples. Isometric exercises are REs that involve holding a position without movement for an extended period of time. The joint angle and muscle length do not change. Simply pressing your hand against the wall is an example of an isometric exercise. Isometric exercises are good choices for people with joint pain.
Although there is some overlap, AE generally improves cardiorespiratory fitness and cardiometabolic variables, and RE enhances muscular strength, muscle mass, and bone density.
ACSM’s Guidelines for Exercise Testing and Prescription encourage those with type 2 diabetes and type 1 diabetes to participate in sufficient volumes of both AE and RE. Several studies have provided evidence to suggest a combination of AE and RE is superior to only AE or only RE.
RE becomes increasingly important with age. In their 2023 review, Yuan and Larsson state that sarcopenia, the medical term for age-related loss of muscle, affects 10% to 16% of older adults globally. Sarcopenia starts around age 30, and from this point, individuals can lose up to 3% to 5% of their muscle mass each decade.
Most men experience a 30% reduction in muscle mass over their lifetime. This reduction in muscle volume is accompanied by a reduction of muscular strength, which has a functional impact in the older population. Physical activity performed throughout a man’s lifetime protects against the development of sarcopenia and the degradation of muscular performance during the latter stages of his life.
Women lose similar amounts of muscle mass as they age. As women progress through menopause, lean body mass decreases by 0.5% annually. Contrary to men who lose both muscle mass and strength as they age, women experience only a reduction in muscle mass with age but retain their strength even in the presence of sarcopenia. Rivera et al. show that older females have strong differences in functionality, even if the sarcopenic process is present, compared with the elderly male population. Factors associated with sarcopenia include diabetes, physical inactivity, poor diet, and smoking.
Skeletal muscle clears 80% of postprandial glucose from the circulation. The loss of muscle mass affects glucose disposal, raising blood glucose levels. RE has much potential for improving the amount of time that blood glucose levels are in target range.
Skeletal muscle plays a crucial role in maintaining one’s resting metabolic rate (RMR). As muscle mass decreases, RMR also decreases. As metabolism slows and fewer calories are burned, weight can increase.
During muscle contraction, the muscles and tendons apply tension on the bones, which stimulates the bones to produce more bone tissue. As a result, bones become stronger and denser, and the risk of osteopenia, osteoporosis, and fractures can decrease.
Skeletal muscle decline can cause a decrease in strength and reduced mobility. This raises the risk of falls and fractures. A 2015 study published in the Journal of Bone and Mineral Research found that people with sarcopenia have more than double the risk of low-trauma fractures from falls. These fractures are the result of a fall from a standing height or less without major trauma (eg, a motor vehicle accident). Low-trauma fractures commonly affect the hip, clavicle, femur, radius, and ulna.
PWD have a higher risk for fractures. Chronic hyperglycemia can compromise bone integrity, making bones more brittle and susceptible to breaks. Complications such as neuropathy and vision loss can also increase the likelihood of falls and resultant fractures. Additionally, early onset type 1 diabetes may impair bone formation and reduce bone density over time.
RE guidelines can differ slightly from author to author, for example, the number of recommended repetitions varies between 8 to 12 and 10 to 15 repetitions. These differences are minimal and generally do not impact outcomes in PWD. For example, ACSM’s Guidelines for Exercise Testing and Prescription recommends completing 10 to 15 repetitions per set. The joint recommendation of ACSM and ADA recommends 8 to 12 repetitions per set.
ACSM/ADA recommendations are consistent with the 2018 Physical Activity Guidelines for Americans.
Perform 8 to 10 multijoint exercises engaging major muscle groups: latissimus dorsi (lats), deltoids, pectorals, biceps, triceps, quadriceps, hamstrings, calves, gluteal muscles, and abdominals.
Perform 1 to 3 sets of 8 to 12 repetitions with good form at least twice a week on nonconsecutive days.
The level of intensity can be determined by using the rate of perceived exertion (RPE) scale. Modified Borg RPE for RE should be 4 to 9 (moderate to vigorous). The RPE scale is designed to identify a perceived level of exercise intensity. During RE, the individual gauges himself or herself with the question, “How hard do I feel I am working?” The RPE scale can also be used by the DCES to prescribe exercise at a desired intensity. “When beginning RE, you should feel that the exercises are at the level of 4 to 8 or somewhat hard; you realize that you’re working, but it feels OK to continue” (see Table 1).
Types of resistance exercise include the following:
Free weights
Weight machines
Resistance bands
Medicine balls/kettlebells
Body-weight exercises
Water-based exercises
Isometric exercises
See Table 2 for simple exercises to introduce to patients.
Low- to moderate-intensity exercise, such as walking, does not need medical clearance. Individuals may already be doing housework, light yardwork, and grocery shopping. These physical activities may be equal to light- to moderate-intensity exercise.
The 2023 Standards of Care in Diabetes state that exercise screening is generally not recommended for PWD who are asymptomatic for cardiovascular disease (CVD). DCESs should be aware that PWD often have risk factors for CVD.
Prior to starting an exercise program, perform a thorough history, including assessing cardiovascular risk factors. Be aware of atypical signs of coronary artery disease: gastrointestinal discomfort, chest pain lacking typical angina symptoms, syncope, cough, and breathlessness. Health care professionals should assess for conditions that might contraindicate certain types of exercise or predispose to injury, such as uncontrolled hypertension, untreated proliferative retinopathy, autonomic neuropathy, peripheral neuropathy, and a history of foot ulcers or Charcot foot.
PWD may be hesitant to begin an RE program. It may be helpful to debunk myths that RE requires complex equipment and a lot of time. RE using appropriate weights may cause minor muscle soreness but should not increase joint pain. Encouraging a consultation with an exercise professional can help reassure the individual. Working with an exercise professional will help PWD choose exercises that are appropriate and will demonstrate good form to maximize effectiveness and minimize chance of injury.
Explaining the following points can help get your patient started with RE.
Break down the misconception that RE is only for bodybuilders or young and fit people. RE is adaptable to all ages and fitness levels.
RE offers immediate benefits, such as improved glucose control and a sense of achievement. As with any high-intensity exercise, RE can elevate blood glucose, and levels should resolve within 30 to 60 minutes of completion of RE.
PWD may be apprehensive about starting RE due to fear of injury or not knowing where to begin. Offer reassurance and guidance on starting safely based on the ACSM/ADA guidelines.
Suggest that the individual start with a light weight; one that doesn’t require much effort to lift.
Complete 1 set of 8 to 12 repetitions. A repetition is a complete movement of an activity, such as lifting and lowering a weight. Add a second and third set over time for added benefit.
Lift and lower the weight in a controlled manner, 2 seconds each, up and down.
The last repetition should be reasonably difficult to complete.
Breathe throughout the exercise.
Share success stories of other PWD you know who have integrated RE into their daily routines. This inspires and gives relatable models to follow.
Encourage starting with small, achievable goals. This could be as simple as incorporating 10 minutes of RE twice a week, gradually increasing the duration and intensity. Celebrate these small victories to boost motivation.
ACSM’s Guidelines for Exercise Testing and Prescription recommends that increases in weight should be done with fewer repetitions, increasing repetitions as tolerated. This increase in resistance can be followed by a greater number of sets and lastly by training frequency.
Regularly check in on their progress, challenges, and experiences. Personalized advice and adjustments can significantly enhance adherence and outcomes.
Tracking progress can be a powerful motivator for PWD. It helps in setting goals, noting improvements, and identifying areas that need adjustment.
Practical tips can help your patient incorporate RE into daily life. Doing squats in front of the television or wall push-ups while waiting for the kettle to boil can help fit RE into a busy schedule.
Highlight the need for proper technique and gradual progression to prevent injuries. This is crucial for individuals with neuropathy or other diabetes complications and those who have not previously carried out RE.
Although AE can have a greater impact on blood glucose than RE, reviewing strategies for avoiding hypoglycemia during and after RE is recommended. Strategies include adjusting a medication dose before exercise, injecting insulin dose into the abdomen instead of exercising limbs, and adjusting the number of snacks. Recommend doing RE before AE to help keep blood glucose stable.
Sulfonylureas stimulate insulin secretion and thus increase hypoglycemia risk during exercise. SGLT2 inhibitors carry a low inherent risk of hypoglycemia.
To help prevent hypoglycemia, recommend that PWD monitor blood glucose before, during, and after new exercise routines until they are aware of how their bodies respond to exercise.
Public libraries, town recreation centers, and senior centers may provide RE classes. Instructors can demonstrate basic RE, answer questions, and give guidance. This also builds a community of support among participants.
Many activities involve RE without being traditional gym-based weightlifting. For example, water-based physical activity is a popular mode of exercise and can be an effective way to build strength and improve overall fitness. Activities such as water aerobics, aquatic Pilates, and underwater weightlifting utilize the buoyancy and resistance properties of water to improve muscle strength. By leveraging the natural resistance of water, these exercises provide a low-impact alternative to traditional strength training, making them ideal for individuals with joint issues or those recovering from injuries. Other examples of nontraditional RE exercises include yoga, Pilates, and Tai Chi.
Create or curate easy-to-understand guides, videos, and infographics on starting RE. Resources should focus on benefits, safety precautions, and simple exercises (Table 3).
Clearly, RE deserves its place in diabetes care and education. For matched improvements in strength, muscle mass, and bone density, no other way exists. RE’s short-term and long-term improvements in blood glucose and weight control, respectively, are added benefits. By incorporating RE into diabetes management plans, we can provide a more holistic approach to health and wellness that goes beyond healthy eating and aerobic exercises.
Peggy Kraus, MA, ACSM-CEP, CDCES, EIM, is in private practice in Hampton Bays, NY.
The authors declare having no professional or financial association or interest in an entity, product, or service related to the content or development of this article.
The authors declare having received no specific grant from a funding agency in the public, commercial, or not-for-profit sectors related to the content or development of this article.
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