Physiological bases for the treatment of the physically active individual with diabetes

A Narrative Literature Review on the Role of Exercise Training in Managing Type 1 and Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia associated with impaired carbohydrate, lipid, and protein metabolism, with concomitant absence of insulin secretion or reduced sensitivity to its metabolic effects. Patients with diabetes mellitus have a 30% more risk of developing heart failure and cardiovascular disease compared to healthy people. Heart and cardiovascular problems are the first cause of death worldwide and the main complications which lead to high healthcare costs. Such complications can be delayed or avoided by taking prescribed medications in conjunction with a healthy lifestyle (i.e., diet and physical activity). The American College of Sports Medicine and the American Diabetes Association recommend that diabetic people reduce total sedentary time by incorporating physical activity into their weekly routine. This narrative literature review aims to summarize and present the main guidelines, pre-exercise cardiovascular screening recommendations, and considerations for patients with diabetes and comorbidities who are planning to participate in physical activity programs.

Identification of the Exercise Load When Using a Balance Exercise Assist Robot

Objectives:

The Balance Exercise Assist Robot (BEAR) is a boarding-type robot developed to improve users’ balance performance. However, the exercise load experienced by users of the BEAR remains unclear. Therefore, this study aimed to identify the exercise load of BEAR users.

Methods:

Recruited healthy participants were fitted with an expiratory gas analyzer, and instructed to control the avatar displayed on the computer monitor by shifting their weight on the BEAR. Three types of activity (tennis, skiing, and rodeo) were prepared for the BEAR, and the difficulty of each activity had 40 levels. Each balance exercise for each level lasted for 90 s. The BEAR was administered at levels 1, 5, 10, and then up to 40 in steps of 5 for each activity. The major parameters that were evaluated were oxygen consumption (grossVO₂, netVO₂), metabolic equivalents (METs), and heart rate (HR). Two-way analysis of variance with Tukey’s post hoc test was applied to each level of each activity.

Results:

Fourteen healthy participants were recruited. For the rodeo activity, netVO₂ and MET values were significantly higher than those for tennis and skiing at level 20 (tennis vs. skiing vs. rodeo: netVO₂ 114.0±59.7 vs. 160.6±71.1 vs. 205.6±82.9, METs 1.47±0.22 vs. 1.72±0.37 vs. 1.90±0.29) and higher. Furthermore, comparisons within activity types showed that at level 40, netVO₂ and MET were significantly higher than for level 1. The exercise intensity was found to increase along with the exercise level for all three activity types, with rodeo being the highest at 2.74 METs.

Conclusions:

The current findings show that the BEAR can be used for balance practice without generating excessive cardiopulmonary stress.

Review: Helping the athlete with type 1 diabetes

Exercise is a significant physiological challenge with markedly increased cardiac output, respiration and fuel mobilisation. Whilst the cardio-respiratory response to exercise is similar in type 1 diabetes to that seen in non-diabetic subjects, the response to mobilisation of fuel source to support exercise is impaired. This effect, when combined with the difficulties of nutrition and insulin therapy in type 1 diabetes may negatively impact on the performance of the athlete with diabetes. Hypoglycaemia both during and following exercise, is a significant risk. Furthermore, hyperglycaemia prior to and following some types of exercises can also be problematic. The effect on blood glucose of varying sports can be predicted, and therefore, pro-active adjustments of insulin therapy and nutrition can be made. This article outlines the important differences seen with exercise in type 1 diabetes and discusses appropriate strategies to normalise performance and reduce the risk of hypoglycaemia.

[The role of exercise in the treatment of type 1 diabetes]

Although physical activity has been associated with cardiovascular mortality reduction in type-1 diabetes (DM1) patients, many points in the topic 'exercise' deserve a closer look. For example: contradictory data have been reported regarding the benefits of physical activity on metabolic control in these patients. Still contradictory is the type of exercise that brings more benefit in this group. Another issue is the best way of reducing insulin doses for exercise. This article intent to discuss these topics. The effect of exercise on metabolic control in DM1 is still contradictory. Some authors show a beneficial effect on glycated hemoglobin (A1c) and others do not. Another point to be analized is which type of exercise is better for these patients: aerobic or of resistance. There is a lack of information related to the effect of resistance exercises without the aerobic training on metabolic control in type-1 diabetes. The effect of exercise on lipid profile in DM1 is another issue. The intensity and duration of the exercises, the level of physical activity, the duration of the disease and the presence of cronic complications are some points that might be taken into consideration before starting an exercise program. Guidelines for the reduction in insulin dose or the use of carbohydrate are strategies to avoid hypoglycemia related to exercises. Hydration and self-monitored blood glucose levels are also very important topics. This article will also discuss the clinical evaluation before doing any exercise.

Exercise and Newer Insulins: How Much Glucose Supplement to Avoid Hypoglycemia?

PURPOSE

To determine the glucose supplement required to prevent hypoglycemia during moderate-intensity exercise in Type 1 diabetic patients using newer analog insulins.

METHODS

Nine subjects performed 60 min of ergocycle exercise (50% VO2max), 3 h after a standard breakfast in three different conditions. Subjects were randomly assigned to preexercise liquid glucose supplement of 0 g of glucose (0G), 15 g of glucose (15G), and 30 g of glucose (30G). Blood glucose (BG) was measured before, during, and following the exercise. All subjects used Humulin N (N) and analog insulin Humalog (Lispro). A dextrose infusion was initiated when BG fell below 5 mmol x L(-1).

RESULTS

There was no significant difference in the magnitude of the decrease in BG exercise-induced when comparing the three experimental conditions. However, the quantity of dextrose infused was significantly higher in the 0G (10.5 +/- 3.2 g) than in the 15G (3.5 +/- 1.8 g) or the 30G conditions (1.6 +/- 1.0 g). The addition of a glucose supplement (15G or 30G) significantly prolonged the delay before the need for dextrose infusion (31.7 +/- 7.5, 51.3 +/- 4.2, and 55.6 +/- 2.6 min; 0G, 15G, and 30G, respectively). The quantity of dextrose infusion was plotted against the three preexercise glucose supplements and a regression equation obtained. Solving this equation, a glucose supplement of 40 g was estimated in order to maintain BG levels within the normal range during and after exercise.

CONCLUSION

For 60 min of late postprandial exercise followed by 60 min of recovery, an estimated 40 g of a liquid glucose supplement, ingested 15 min prior exercise, would seem likely to help maintain safe BG levels in subjects using N-Lispro.

Efeito da hidratação com carboidratos na resposta glicêmica de diabéticos tipo 1 durante o exercício

Não está claro se a ingestão de carboidratos (CHO) através de bebidas esportivas pode manter a glicemia em diabéticos tipo 1. A finalidade deste estudo foi examinar a glicemia em adolescentes com diabetes tipo 1 que ingeriram bebidas esportivas com 6% de CHO durante e após o exercício. Dez adolescentes (5 meninas e 5 meninos, 15,3 ± 2,4 anos) com o diabetes controlado (HbA1c < 12%), e sem complicações da doença, exercitaram-se em um cicloergômetro a 55-60% do pico máximo de consumo de O2 (VO2pico) durante 60 minutos em dois dias separados. Em ordem randomizada e desenho duplo-cego, os sujeitos ingeriram (5ml·kg-1 antes do exercício, e 2ml·kg-1 a cada 15 minutos de exercício) bebida esportiva com 6% de CHO ou água com sabor sem CHO (placebo) com cor e sabor similares aos da bebida esportiva. Após uma hora de exercício, a glicemia não diminuiu significativamente quando foi ministrada bebida esportiva (CHO-6%) (221,0 ± 78 para 200,5 ± 111mg·dL-1, p > 0,05), e diminuiu significativamente na situação placebo (282,9 ± 85 para 160,2 ± 77mg·dL-1, p < 0,05) (9 vs. 43,2%). Após 30 minutos de recuperação, a glicemia foi de 177,2 ± 107mg·dL-1 com CHO e 149,1 ± 69,6mg·dL-1 com placebo, representando 20,1% e 47,3% dos níveis pré-exercício. Não foram encontradas diferenças significativas entre as situações na freqüência cardíaca, taxa de percepção de esforço, na insulina e eletrólitos sanguíneos. Não foram encontradas alterações no hematócrito e hemoglobina durante o exercício, indicando que os sujeitos permaneceram euidratados. Em conclusão, o uso de bebidas contendo 6% de CHO atenuou a redução da glicemia induzida pelo exercício em adolescentes com diabetes tipo 1.

The effects of mountain exercise in Parkinsonian persons - a preliminary study

Persons suffering from Parkinson's disease (PD) show variable motor manifestations such as gait dysfunction and hypokinesia as well as psychosocial manifestations like emotional and social impairment. In order to assess short- and midterm impact on PD persons from a comprehensive training concept, we launched a study with daily walks in the Swedish mountains during 1 summer week. The 3-6 km daily walking tours in hilly terrain were combined with lectures about the disease and self-training, social intercourse and a general encouraging atmosphere brought about by three accompanying leaders. The participants stayed in a mountain pension during the week. Nineteen mild to moderate PD persons volunteered and were assessed before (0 weeks), immediately after (1 week), and 4 months later (18 weeks) by a self-reporting questionnaire containing four subscales. These covered the domains PD symptoms, systemic symptoms, emotional functioning, and social functioning. There was a general improvement in PD scores at 1 week compared to baseline. This was not sustained at the 18-week follow-up. We postulate the results were due to a combination of information, professional guidance, exercise in hilly terrain with environmental visual cues, social interaction, and comparison with the others. Further research should aim at pinpointing the most essential components to achieve short- as well as midterm improvements. We believe there is a need to focus on patients' self-reported health to a greater extent than today in order to complement traditional rehabilitation and training outcome measures.

Diabetes and exercise

Exercise is frequently recommended in the management of type 1 and 2 diabetes mellitus and can improve glucose uptake by increasing insulin sensitivity and lowering body adiposity. Both alone and when combined with diet and drug therapy, physical activity can result in improvements in glycaemic control in type 2 diabetes. In addition, exercise can also help to prevent the onset of type 2 diabetes, in particular in those at higher risk, and has an important role in reducing the significant worldwide burden of this type of diabetes. Recent studies have improved our understanding of the acute and long term physiological benefits of physical activity, although the precise duration, intensity, and type of exercise have yet to be fully elucidated. However, in type 1 diabetes, the expected improvements in glycaemic control with exercise have not been clearly established. Instead significant physical and psychological benefits of exercise can be achieved while careful education, screening, and planning allow the metabolic, microvascular, and macrovascular risks to be predicted and diminished.

Oral glucose ingestion increases endurance capacity in normal and diabetic (type I) humans

The effects of an oral glucose administration (1 g/kg) 30 min before exercise on endurance capacity and metabolic responses were studied in 21 type I diabetic patients [insulin-dependent diabetes mellitus (IDDM)] and 23 normal controls (Con). Cycle ergometer exercise (55-60% of maximal O2 uptake) was performed until exhaustion. Glucose administration significantly increased endurance capacity in Con (112 +/- 7 vs. 125 +/- 6 min, P < 0.05) but only in IDDM patients whose blood glucose decreased during exercise (70.8 +/- 8.2 vs. 82.8 +/- 9.4 min, P < 0.05). Hyperglycemia was normalized at 15 min of exercise in Con (7.4 +/- 0.2 vs. 4.8 +/- 0.2 mM) but not in IDDM patients (12.4 +/- 0.7 vs. 15.6 +/- 0.9 mM). In Con, insulin and C-peptide levels were normalized during exercise. Glucose administration decreased growth hormone levels in both groups. In conclusion, oral glucose ingestion 30 min before exercise increases endurance capacity in Con and in some IDDM patients. In IDDM patients, in contrast with Con, exercise to exhaustion attenuates hyperglycemia but does not bring blood glucose levels to preglucose levels.

Managing Activity in Patients Who Have Diabetes

In brief Control of both type I and type II diabetes involves the appropriate balance of exercise, diet, and medication. Regular, long-term exercise has many benefits for people with diabetes. Physicians can educate patients about ways to regulate and monitor blood glucose before, during, and after a workout or competition. Physicians also need to discuss the warning signs of hypoglycemia, hyperglycemia, ketoacidosis, and dehydration and how to prevent the conditions. In addition, patients who have type I diabetes need to know the effects of exercise on insulin requirements. Nutrition needs will vary for each patient, type of activity, and other factors, but food intake can be readily adjusted in conjunction with blood glucose monitoring.

Zinc content in selected tissues in streptozotocin-diabetic rats after maximal exercise

The Zn metabolism in experimental diabetic rats after maximal exercise was investigated. Forty male wistar rats were used, weighing 240 +/- 10 g at the beginning of this experiment. The animals were assigned to one of four experimental groups (n = 10): control at rest (CR), control plus exercise (CE), diabetic at rest (DR), and diabetic plus exercise (DE). Experimental diabetes was produced by a single intraperitoneal injection of streptozotocin (STZ) (60 mg/kg). Thirty days after injection of streptozotocin, the animals of groups CE and DE were forced to acute exercise (swimming) until exhaustion. Glucose, rectal temperature (RT), pH, swimming time (ST), hematocrit (Hct), serum, and tissue (heart, liver, kidney, and muscle) Zn concentrations were measured. The streptozotocin treated animals used in the current experiment were diabetic. Increases in hepatic, renal, muscle, and serum levels Zn at rest and after exercise until exhaustion were found in normal and diabetic rats. ST decreased (-180%) in the diabetic rat group. In conclusion, the results of the present study indicate that STZ-induced diabetes was associated with altered tissue Zn concentration, both at rest and after exercise.

Exercise tolerance is lower in type I diabetics compared with normal young men

The present investigation was conducted to study metabolic and hormonal responses to prolonged exercise to exhaustion in insulin-dependent diabetic subjects. Sixteen healthy subjects (control) and 15 diabetics with no-insulin administration for 12 hours were studied. They were submitted to short-term exercise to exhaustion on a cycle ergometer at 55% to 60% of maximum oxygen consumption (VO2max). Exercise tolerance was significantly lower in diabetic subjects (66 +/- 6.7 v 117 +/- 9.4 minutes), and glucose concentration was significantly higher in these subjects. At exhaustion, only diabetic subjects showed a significant decrease in glycemia (142 +/- 20 v 111 +/- 16 mg/dL). Lactate concentration increased significantly during exercise up to 30 minutes, but at exhaustion only control subjects showed a reduction. No significant difference in free fatty acid (FFA) concentrations was observed between the groups during a 30-minute exercise period; however, at exhaustion levels were significantly higher in control subjects. Prolactin and C-peptide concentrations were significantly lower in diabetic subjects, whereas glucagon concentration was higher. No significant differences between the groups were observed for cortisol and growth hormone (GH) concentrations. We conclude that (1) diabetic subjects show reduced exercise tolerance when no insulin is administered for 12 hours, and (2) exercise to exhaustion reduces serum glucose concentrations in insulin-dependent diabetics.

Control of type II diabetes. Reaping the rewards of exercise and weight loss

After a complete physical examination to identify possible complications, patients with non-insulin-dependent (type II) diabetes mellitus should be placed on an exercise program and a weight-control diet. Individualizing these regimens according to patients' health goals and personal interests enhances the chance of success. Exercise guidelines must be followed to ensure the patient's safety. Weight loss, however moderate, should be encouraged, and once a reasonable weight is obtained, a balanced maintenance diet should be recommended. Patience and persistence by physicians and patients can bring success in management of type II diabetes with nonpharmacologic means.