Exercise and Weight Loss in Diabetes and Coronary Artery Disease

Andrew Heilbrunn

Biokinetics Department, Centre for Diabetes and Endocrinology, Johannesburg

In the last five decades, there has been numerous diabetes, exercise and weight loss related research. The majority of researchers have shown that exercise and decreased total and visceral body fat play an extremely important role in both the prevention and the treatment of Type 2 Diabetes and Coronary artery disease.

Traditionally the preferred approach to weight loss was calorie restriction.  Exercise was seen as a means of maintaining weight lost. In fact, studies suggest that it is easier to maintain ones goal weight through regular exercise than through continued calorie restriction.

The overweight population were of the opinion that it was necessary to lose a significant amount of body weight in order to bring about healthy, physiological adaptations. However a 5 to 7% reduction in visceral and total body fat may be associated with lower blood pressure, lower cholesterol and lower blood glucose levels. (Movsas S, 2008)

Exercise, Diabetes and Coronary Artery Disease

Between 1960 and 2000, Paffenbarger and Blair initiated longitudinal, follow up physical activity studies on more than 80 000 subjects. They compared the “active” to the “non-active” and the “fit” to the “unfit” subjects and observed the relationship between activity patterns and the risk of developing cardiovascular disease, obesity, diabetes and other chronic illnesses. Their findings contributed enormously to establishing a relationship between physical activity and reduction in risk of mortality from certain chronic illnesses, in particular cardiovascular disease.  Subjects categorised as” unfit”, had the highest Coronary Artery and Cerebrovascular disease death rates.  The risk of being “unfit” appeared to be a higher risk for coronary artery disease than high blood pressure, high cholesterol and obesity.

Eighty to ninety percent of patients with type 2 diabetes are overweight or obese. A personal and a familial history of obesity, caused by poor eating habits and a sedentary lifestyle and compounded by weight gain related to Sulphonylurea and Insulin utilization, mean that many struggle with weight loss. In light of the above, Blair and Paffenbarger’s findings suggested that as long as you were “relatively fit”, even if you were overweight, you would have a lower risk of coronary artery disease.

How much exercise is necessary to bring about weight loss and physiological changes to decrease mortality?

The amount of exercise necessary to bring about healthy adaptations is somewhat controversial.  Paffenbarger suggests that people should try to burn 1500 to 2500 calories per week, which equates to approximately 60-90 minutes of brisk walking per day.  Blair concluded that one would benefit from exercise (5-7 times per week) at 60-85% aerobic capacity (duration 30-60 min). The American College of Sports Medicine (ACSM) advocated 30-60 minutes per day of moderate intensity physical activity, (A brisk walk) was sufficient. The latest literature suggests that in order to bring about weight loss through exercise alone, one would have to exercise for more than 60 minutes per day. Based on the results of our own research, as well as the work of researchers such as Blair, Paffenbarger, Sigal and Eves we recommend a combination of moderate calorie reduction and 3 to 5 weekly exercise sessions of 45 to 60 minutes duration performed at a moderate to high intensity (i.e. brisk walking and / or a moderate intensity, resistance-training circuit). In addition, we suggest participating in informal activity such as stair climbing, gardening, shopping or housework daily.

Moderate physical activities performed throughout the day, adding up to a total of 60 minutes of activity by the end of the day, appear to have the same physiological health benefits as one continuous bout of exercise lasting 60 minutes. This may come as a surprise to the sedentary person who views exercise as a daunting and demanding task.  Small, regular and progressive activities taken throughout the day can combine to offer the same rewards as 30-60 minutes in a fitness centre.

Which type s of exercise should people participate in, in order to reduce body-fat percentage?

There are generally 2 modes of exercise people can participate in:

1.       Endurance exercise such as walking, cycling, jogging and swimming.  These are activities which involve low intensity exercise carried out continuously for a long period of time.

2.       Resistance or interval type exercise which involves a higher intensity type of exercise carried out in short bursts with rest intervals, such as a resistance training circuit or most types of ball sports.

There is some controversy surrounding the mode of exercise that people should participate in, in order to bring about visceral and total body-fat loss.  Endurance activities at a low to moderate intensity (60% of ones theoretical heart rate maximum) were traditionally seen as the best way to utilize fat as a primary energy source; however, recent findings suggest that this low intensity utilized a negligible amount of fat in 60 minutes.  In reality one would have to cycle, walk or jog at 60% VO2 max for 2-3 hours per day in order to bring about significant fat percentage reduction.  On the other hand, higher intensity interval or intermittent exercise for 60 minutes, 3 to 4 times per week increases ones basal metabolic rate for a longer period than low intensity endurance training and this may be more beneficial in body-fat percentage reduction.

In an exercise and Type 2 diabetes research concluded in 2007, the combination of endurance and resistance type activities seemed to improve blood glucose control and reduce visceral adiposity more significantly than endurance or intermittent type activities individually. (Sigal RJ, 2007).  One of the explanations for this positive result was a better exercise compliance with a combination of exercises.  Furthermore, in a meta-analysis of exercise and Type 2 diabetes studies, involving 377 subjects, exercise significantly improved visceral adiposity, glycemic control and triglycerides, even in the absence of significant weight loss (Sojung, L, 2007)

In a recent study comparing people participating in a Weight Watchers programme to those participating in regular activity at commercial fitness centres, weight loss was more significant in the Weight Watchers group.  However, when the data was analysed, it was clear that the majority of weight lost in the Weight Watchers group was lean tissue and not fat. Although the fitness centre group lost less weight, intra-abdominal fat was significantly lower than the Weight Watchers group.  Intra-abdominal fat, which is more predictive of Cardiovascular disease was measured with Computer Tomography (CT scans).  These results suggest that exercise, without significant weight loss may have a positive influence on the Metabolic Syndrome (Ball S, 2008).

Exercise Prescription and barriers to exercise

Various medical and physical concerns will govern the type, intensity and duration of exercise an individual is capable of performing safely.  Several lifestyle and socio-economic issues such as motivation, personal goals and preferences, stage of change and cultural influences will also affect the type of exercise intervention developed and its implementation.  Written exercise instructions may help with adherence to an exercise programme.  However, of more importance is the level of support the Physician, Educator and exercise physiologist gives the patient regarding the uptake of activity.  Physician support, patient consultation, specific advice regarding the type, time and intensity of the exercise programme and the setting of appropriate and realistic goals appear to be the strongest predictors of adherence. Furthermore exercising in a group environment or under personal supervision has been shown to improve long term exercise compliance. (Penny B, 2007).

Conclusion

Exercise and calorie restriction have their pros and cons, however the combination may produce the best physiological results. Comprehensive lifestyle therapies, involving nutritional therapy, daily exercise, and behavioural modification, can lead to a 5-7% reduction in visceral and total body fat percentage over 10 to 20 weeks.

Exercise can play a key role in the prevention and management of obesity and diabetes.  It can improve glycaemic control, reduce adiposity, reduce cardiovascular risk and improve quality of life.  Both Endurance and Resistance training modalities should form the cornerstone of any exercise programme.  Prescribed correctly and with adequate considerations of the barriers, motivators and medical concerns facing people with diabetes, exercise can be an extremely safe and effective treatment strategy.

EXERCISE TRAINING AND HIV

BY: Suzann Knoetzen

Patients with HIV infection, but without acquired immunodeficiency syndrome (AIDS) or pulmonary disease, have a reduced workload, lower anaerobic threshold, and poorer aerobic capacity than do age-matched controls (Roubenoff, Skolnik, Shevitz, Snydman, Wang, Melanson & Gorbach, 1999).  During the course of the illness the HIV positive patient may experience muscle wasting and weakness, fatigue and depression (Mustafa, Sy, Macera, Thompson, Jackson, Selassie & Dean, 1999).  Exercise training is an appealing addition to antiretroviral therapy in rehabilitating the exercise capacity and functional status of patients with HIV infection.  Both aerobic and resistance training may be important adjuncts to the antiretroviral treatment of HIV infection (Roubenoff et al., 1999).  The aerobic exercise prescription for HIV infected individuals has typically involved the use of treadmill walking and stationary cycling.  These modes of exercise have typically been performed 3 days per week for a total duration of 10-24 weeks at intensities ranging between 50% - 80% VO2max or 60% - 85% maximum heart rate (Dudgeon, Phillips, Bopp & Hand, 2004). Several studies reviewed by Dudgeon et al. (2004) revealed that resistance training programs for HIV infected persons generally consisted of 3 sessions per week with 3 sets of 8 repetitions on each exercise.  Furthermore, it was found that when aerobic and resistance training were combined the programs usually lasted 12-16 weeks and included 20 minutes aerobic exercise followed by 35 to 40 minutes of resistance training.     

The success of exercise in effectively reducing the risk of cardiovascular and other chronic diseases as well as improving mental health is well documented.  Several studies involving HIV infected individuals in a structured program of moderate physical activity for periods ranging from 8-15 weeks led to enhanced immunity and lower risk of some infections.  Some randomized control studies suggested beneficial effects of exercise on immunologic and psychological parameters in HIV positive individuals.  Furthermore, several reports have been made concerning improvement in muscle strength and flexibility, cardiopulmonary function, decreased anxiety, depression and anger, and increase in the CD4 cell counts following exercise training (Mustafa et al., 1999).  

The goals of regular aerobic exercise training in HIV positive patients include:

·        Improved aerobic capacity and functional status;

·        Improved immune function;

·        Maintenance of or improvements in lean body mass/weight;

·        Improved mood (reduced depressive symptoms); and

·        Improvement in quality of life (Stringer, 1999).

Short term bouts of exercise do enhance the number of CD4 cells, neutrophils and cells mediating natural immunity in HIV-seropositive patients.  There is as yet no convincing data that longer term exercise is associated with improved resting levels of CD4 cells in HIV patients.  Exercise training does not however, appear to adversely affect HIV positive patients (Nieman et al., 1999).  Several studies with symptomatic and asymptomatic HIV positive patients indicate that aerobic exercise may produce a health benefit by direct improvement of cardiopulmonary, immune system function and quality of life (Perna, LaPerriere, Klimas, Ironson, Perry, Pavone, Goldstein, Majors, Makemson, Talutto, Schneiderman, Fletcher, Meijer & Koppes, 1999).

The benefits of eating a High GI carbohydrate meal after exercise.

When most people hear the word Hi GI food they run for the hills because of the “negative” connotations and how high Gi food is linked with weight gain. BUT there are two important times of day that High Gi carbohydrates can be taken in, the first is with breakfast in the morning because you are coming off a "fast". So, at that time you want a simple carbohydrate source to “re start the metabolism. And the second time of day and the one that will be discussed is straight after exercise.

Firstly what must be understood is what High GI is or High Glycemic foods. The Glycemic Index is a measure of how quickly a food raises blood sugar and hence insulin levels. A high Glycemic carbohydrate source is 70 and above.

The reason that the Hi Gi carbohydrates are critical is because it starts the whole recovery/muscle growth process. Following a hard workout, your body is severely depleted of glycogen and glucose.

During the workout working muscles use glucose (usable energy in the blood) and glycogen (stored energy from the liver and muscles) for energy. As such, there is a point at which blood glucose levels and glycogen levels get so low that intense exercise can't continue. There just isn't enough available energy for your muscles to use.

Once this occurs the hormone cortisol is secreted, this is your body's "stress" hormone and it has very catabolic (catabolism is the process that the break down of molecules into smaller units and release energy)  What cortisol does (being catabolic) is it uses up muscle tissue for protein and convert it into glucose. A process called gluconeogenesis ensues, producing glucose from these amino acids in the liver. The net result is a loss of muscle tissue.

The post-workout meal prevents this. It also allows insulin to be released, one of several anabolic hormones in the body and that is why it is critical to get the carbs to the muscle cells as fast as possible. As well, the elevated insulin levels will help to drive nutrients into the muscle cells and prevent that unwanted muscle breakdown and start the recovery process.

So we see that Hi Gi carbs have their place and it’s all a matter of timing!

What is this infamous rotator cuff?

By Megan Mac Vay

I have often heard people mention that they have or have previously had a “rotator cuff” problem but rarely have these persons actually known or understood what a rotator cuff is or what the injury was to begin with. This may be the result of poor explanation from the practitioner, but most often is as a result of this term being freely used amongst the general public for any sort of shoulder pain or injury.

So today I am going to hopefully clear up any misunderstandings. Your rotator cuff is made up of the muscles and tendons deep within your shoulder joint which connect your upper arm bone (Humerus) with your shoulder blade (Scapula). They also help hold the ball of your humerus firmly in your shoulder socket. The combination results in the

greatest range of motion of any joint in your body and provides an unbelievable strength and stability used in everyday life but most importantly in so many sports (I.e. Bowling in cricket). Therefore, in terms of importance, this area of your body may be considered your most valuable feature.

An injury to your rotator cuff includes any type of irritation or damage to your rotator cuff muscles or the tendons, and as such there are three classifications of an injury associated with it:

• Strain – The tendons stretch but do not tear.
• Partial Tear – There is a partial tear to a tendon but it does not completely sever.
• Full Tear – The tendon or muscle tears completely.

Injuries (of each classification) can result from a multitude of movements, forces, and other factors including:

• Attempting to block/cushion a fall with one’s upper arm.
• Thrusting one’s arm up forcefully against resistance.
• Excessive overhead activity.
• Repetitive trauma.
• Degeneration of muscles (with age or use).
• Lack of blood supply.
• Bone spurs (bone overgrowth).

Injury to this area can leave you with large losses of ability and independence, unless you take the steps necessary to rehabilitate the rotator cuff muscles and/or tendons involved before, during and after dysfunction.

Some causes of injury to your rotator cuff, such as degeneration, may take longer to become evident than others. Despite the differences due to the various causes however, there are some telltale signs that you have incurred an injury.

They are:

• Pain when resting, particularly when lying on the injured arm/shoulder.
• Pain during specific movements, such as lowering or lifting your arm.
• Weakness, difficulty lowering or rotating your arm/shoulder.
• A crackling sensation during certain arm/shoulder movements.
• Difficulty with routine activities such as hair brushing.
• Loss of range of motion.

For minor injuries, you can care for your shoulder at home, with rest, cold packs, and over the counter pain medication. Rest implies that you limit the number of overhead and other straining activities you may normally do. Should you get to the point that the pain does not go away with such care however, you will want and need to see a doctor who may advise physiotherapy or exercise with a Biokineticist.

In conclusion, pain in the shoulder region can often be as a result of an injury to the rotator cuff muscles or tendons but will need to be diagnosed by a medical professional. If you do suspect a minor injury, be careful and respect the joint. Should the pain and disability increase, please find medical assistance as soon as possible so as to avoid further injury to the region.

The Difference Between the Effects of a Sprint vs. a Slow Run on Glucose Levels

Written by: Tanya Bellon, Biokineticist

Exercise uses one of two energy systems, aerobic or anaerobic. A good understanding of these 2 energy systems is critical to understanding the exercise challenges faced by individuals with diabetes.  Furthermore this knowledge will aid people with diabetes to ingest the correct snacks and make appropriate insulin dosage adjustments before during and after exercise.

What is Aerobic exercise?

In aerobic exercise such as jogging or cycling, the body uses oxygen to produce energy.  During these exercises, the muscles use oxygen to convert glucose into usable energy for the body.

Why does aerobic exercise cause Hypoglycaemia?

Aerobic activities increases the blood and oxygen supply to the body, causing an increase in insulin circulation. As the length and intensity of the exercise increases so will the demand for energy. This will make the muscles more insulin sensitive therefore increasing the glucose uptake and lowering blood glucose.

Benefits of Aerobic Exercise for both diabetic and non-diabetic people

·         Strengthens heart and lungs

·         Improves muscle sensitivity reducing glucose levels

·         Reduces blood pressure and cholesterol

What is Anaerobic Exercise?

Anaerobic exercise is short and intense, just think of Brian Habana sprinting 50metres to the try line, or a person doing a gym circuit with rest intervals between exercises. The energy to perform this is created without using oxygen. Energy (glycogen) stored in the muscles and liver is converted into usable energy (glucose).

Most sports involve a combination of aerobic and anaerobic energy systems for example rugby and soccer.

Benefits of Anaerobic Exercise for both diabetic and non-diabetic people

·         Builds muscle

·         Strengthens bones

·         Improves speed and power

·         Increases muscle metabolism

Effect of high intensity anaerobic type exercise on a person with Type 1 diabetes

Glucose levels may spike within twenty minutes of starting to a high intensity anaerobic type activity like squash. This reaction known as “Liver dumping” happens because the liver literally “dumps” large amounts of glucose into the blood stream. Intense exercise can cause an adrenal stress response (“flight or fight”) causing increased glucose allowing one to move rapidly or lift a heavy weight.  Consult your doctor or nurse educator when making insulin dosage adjustments or snack adjustements with this type of activity.

Effects of combining Aerobic and Anaerobic exercise for people with Type II diabetes

Research shows that a combination of aerobic and resistance (Anaerobic) training has far greater benefits than only aerobic or resistance training. Patients who walk on the treadmill and do weight training had a greater improvement in their HbA1c than just walking or weight training alone.

In type 1 diabetes the combination of moderate intensity (aerobic) and high intensity (anaerobic exercise) may prevent hypoglycaemia post exercise because of the adrenal response keeping the blood glucose levels higher after exercise. 

Conclusion and Recommendations

It is recommended that aerobic and anaerobic type exercises are incorporated into an exercise programme. People with Type 2 diabetes will experience improvements in overall glucose control, decreased body fat percentages and reduced coronary heart risk factors.

 People with Type 1 diabetes will also show an improvement in glucose control, lowered coronary risk and lowered body fat percentage if they exercise daily or alternate days.  However they need to monitor their blood glucose response to various exercises and then make changes to insulin and snacks accordingly.  In Type 1 diabetes preventing hypoglycaemia during and after activity will improve long term compliance and enjoyment of exercise.

Before starting any exercise programme it is important to have a medical check up with your doctor  to ensure that you are safe to exercise.