The adoption and maintenance of physical activity are critical foci for blood glucose management and overall health in individuals with diabetes and prediabetes. Recommendations and precautions vary depending on individual characteristics and health status. In this Position Statement, we provide a clinically oriented review and evidencebased recommendations regarding physical activity and exercise in people with type 1 diabetes, type 2 diabetes, gestational diabetes mellitus, and prediabetes.Physical activity includes all movement that increases energy use, whereas exercise is planned, structured physical activity. Exercise improves blood glucose control in type 2 diabetes, reduces cardiovascular risk factors, contributes to weight loss, and improves well-being (1,2). Regular exercise may prevent or delay type 2 diabetes development (3). Regular exercise also has considerable health benefits for people with type 1 diabetes (e.g., improved cardiovascular fitness, muscle strength, insulin sensitivity, etc.) (4). The challenges related to blood glucose management vary with diabetes type, activity type, and presence of diabetes-related complications (5,6). Physical activity and exercise recommendations, therefore, should be tailored to meet the specific needs of each individual. TYPES AND CLASSIFICATIONS OF DIABETES AND PREDIABETESPhysical activity recommendations and precautions may vary by diabetes type. The primary types of diabetes are type 1 and type 2. Type 1 diabetes (5%-10% of cases) results from cellular-mediated autoimmune destruction of the pancreatic b-cells, producing insulin deficiency (7). Although it can occur at any age, b-cell destruction rates vary, typically occurring more rapidly in youth than in adults. Type 2 diabetes (90%-95% of cases) results from a progressive loss of insulin secretion, usually also with insulin resistance. Gestational diabetes mellitus occurs during pregnancy, with screening typically occurring at 24-28 weeks of gestation in pregnant women not previously known to have diabetes. Prediabetes is diagnosed when blood glucose levels are above the normal range but not high enough to be classified as diabetes; affected individuals have a heightened risk of developing type 2 diabetes (7) but may prevent/delay its onset with physical activity and other lifestyle changes (8). TYPES OF EXERCISE AND PHYSICAL ACTIVITYAerobic exercise involves repeated and continuous movement of large muscle groups (9). Activities such as walking, cycling, jogging, and swimming rely primarily on aerobic energy-producing systems. Resistance (strength) training includes exercises with free weights, weight machines, body weight, or elastic resistance bands. Flexibility exercises improve range of motion around joints (10). Balance exercises benefit gait and prevent falls (11). Activities like tai chi and yoga combine flexibility, balance, and resistance activities.

Key points• People with age over 60 years, obesity, cardiovascular disease, pulmonary disease or long-standing diabetes are at increased risk of heat-related illness during heat waves because of physiological impairments in the regulation of body core temperature in hot conditions.• A homebound lifestyle, lack of contact with other people and decreased mobility can also contribute to an increased risk of heat-related illness.• Working home air conditioners, fans, access to transportation and access to cool environments during prolonged heat events have a protective effect against heat-related illness and deaths.• Physicians should be aware of these risk factors and protective factors against heat illness, and should counsel at-risk patients accordingly.CMAJ 2009. DOI:10.1503/cmaj.081050Previously published at www.cmaj.caReview rise in body core temperature may lead to heat illness and eventually death. Exposure to the combination of external heat stress and metabolically generated heat can lead to heat-related disorders. The prevalence of heat stress symptoms increases in direct proportion to the elevation of body core temperature. The major heat-related disorders -heat cramps, heat exhaustion and heatstroke -involve various degrees of thermoregulatory failure, which occurs when a person is exposed to excessive heat or elevations in body core temperature over a prolonged period. Risk factors for heat stress AgeObservational studies have shown that people aged 60 years and older are among the worst affected by extreme heat, 3−5 with those living in institutions, confined to bed or living alone having the highest rates of illness, injury and death. 5,8,15−17 In their ecological time-series study, Fouillet and associates 2 showed that during the 2003 heat wave in Europe, mortality ratios (ratios of observed deaths to expected deaths) in France increased continuously with age, from 1.3 for people 35-74 years of age to more than 1.7 for those over the age of 75 (Figure 1). Although the greater prevalence of comorbidities and medication use in this population may be responsible for some of the heat-related deaths, laboratory-based physiological studies have indicated that the ability to sense heat 20 and to manifest appropriate behavioural (especially fluid intake) 21−26 and physiological (e.g., blood distribution, sweating) responses 27−33 during exposure to heat may be compromised in otherwise healthy older individuals.The ability to physiologically maintain body core temperature during heat stress becomes compromised with age. 27 This decrease in thermoregulatory ability can be attributed to a combination of factors, including changes in sweating, [28][29][30]34 blood flow to the skin 30,31,34,35 and cardiovascular function. 32The problem can be exacerbated by the decreases in overall physical fitness and increases in body adiposity that may accompany aging. 36 Experts have suggested that, in combination, these age-related changes in thermoregulatory and cardiovascular function can decrease the body's abilit...

Age-associated functional declines and the accompanying risk of work-related injury can be prevented or at least delayed by the practice of regular physical activity. Older workers could optimally pursue their careers until retirement if they continuously maintain their physical training.

OBJECTIVETo determine the effects of exercise order on acute glycemic responses in individuals with type 1 diabetes performing both aerobic and resistance exercise in the same session.RESEARCH DESIGN AND METHODSTwelve physically active individuals with type 1 diabetes (HbA1c 7.1 ± 1.0%) performed aerobic exercise (45 min of running at 60% V̇o2peak) before 45 min of resistance training (three sets of eight, seven different exercises) (AR) or performed the resistance exercise before aerobic exercise (RA). Plasma glucose was measured during exercise and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise.RESULTSSignificant declines in blood glucose levels were seen in AR but not in RA throughout the first exercise modality, resulting in higher glucose levels in RA (AR = 5.5 ± 0.7, RA = 9.2 ± 1.2 mmol/L, P = 0.006 after 45 min of exercise). Glucose subsequently decreased in RA and increased in AR over the course of the second 45-min exercise bout, resulting in levels that were not significantly different by the end of exercise (AR = 7.5 ± 0.8, RA = 6.9 ± 1.0 mmol/L, P = 0.436). Although there were no differences in frequency of postexercise hypoglycemia, the duration (105 vs. 48 min) and severity (area under the curve 112 vs. 59 units ⋅ min) of hypoglycemia were nonsignificantly greater after AR compared with RA.CONCLUSIONSPerforming resistance exercise before aerobic exercise improves glycemic stability throughout exercise and reduces the duration and severity of postexercise hypoglycemia for individuals with type 1 diabetes.

OBJECTIVEIn type 1 diabetes, small studies have found that resistance exercise (weight lifting) reduces HbA1c. In the current study, we examined the acute impacts of resistance exercise on glycemia during exercise and in the subsequent 24 h compared with aerobic exercise and no exercise.RESEARCH DESIGN AND METHODSTwelve physically active individuals with type 1 diabetes (HbA1c 7.1 ± 1.0%) performed 45 min of resistance exercise (three sets of seven exercises at eight repetitions maximum), 45 min of aerobic exercise (running at 60% of Vo2max), or no exercise on separate days. Plasma glucose was measured during and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise.RESULTSTreatment-by-time interactions (P < 0.001) were found for changes in plasma glucose during and after exercise. Plasma glucose decreased from 8.4 ± 2.7 to 6.8 ± 2.3 mmol/L (P = 0.008) during resistance exercise and from 9.2 ± 3.4 to 5.8 ± 2.0 mmol/L (P = 0.001) during aerobic exercise. No significant changes were seen during the no-exercise control session. During recovery, glucose levels did not change significantly after resistance exercise but increased by 2.2 ± 0.6 mmol/L (P = 0.023) after aerobic exercise. Mean interstitial glucose from 4.5 to 6.0 h postexercise was significantly lower after resistance exercise versus aerobic exercise.CONCLUSIONSResistance exercise causes less initial decline in blood glucose during the activity but is associated with more prolonged reductions in postexercise glycemia than aerobic exercise. This might account for HbA1c reductions found in studies of resistance exercise but not aerobic exercise in type 1 diabetes.

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Regular exercise is important for health, fitness and longevity in people living with type 1 diabetes, and many individuals seek to train and compete while living with the condition. Muscle, liver and glycogen metabolism can be normal in athletes with diabetes with good overall glucose management, and exercise performance can be facilitated by modifications to insulin dose and nutrition. However, maintaining normal glucose levels during training, travel and competition can be a major challenge for athletes living with type 1 diabetes. Some athletes have low-to-moderate levels of carbohydrate intake during training and rest days but tend to benefit, from both a glucose and performance perspective, from high rates of carbohydrate feeding during longdistance events. This review highlights the unique metabolic responses to various types of exercise in athletes living with type 1 diabetes.