This is the first in a series of articles related to specific health conditions in the context of Masters swim training and competition. They will include recommendations to maximise safety, health and of course, performance. Planned future topics include cardiovascular problems, pregnancy and muscle and joint dysfunction. The content has been reviewed for accuracy by a medical doctor, but swimmers should always seek advice from their own physician.

Sweet! A Discussion on Diabetes and Swimming

Diabetes mellitus is the group of disorders that share glucose intolerance as their common thread. There are two main cateogories: Type 1, caused by an immune system attack, occurs suddenly and requires administration of insulin; it is sometimes called juvenile diabetes because it typically appears at a young age. Type 2 emerges gradually, usually after age 40, may or may not require medication and is associated with obese, sedentary individuals. Gestational diabetes is experienced by some women ? it will be discussed further in an upcoming article on pregnancy and training.

Exercise is an integral part of an effective diabetes management program. And it's worth the effort it takes: an individual with diabetes is at increased risk for many other conditions. A noteworthy example is increased likelihood for diabetics, by a factor of 2-4, of being a victim of stroke or heart disease compared to the non-diabetic population. Fortunately, exercise reduces risk considerably. Risk of complications include all forms of cardiovascular disease, all-cause mortality, blindness, kidney disease, dental disease, peripheral neuropathy and stroke, circulatory disease, joint swelling, eating disorders, and mood disorders.

A primer: explanation of medical conditions and terms related to Diabetes

In our navigation of the body's response to diabetes in training, it will be useful to understand the following:

Blood Glucose level (we'll call it BS) is often called blood sugar ? and refers to the quantity of glucose dissolved in our blood and available for uptake by the body.

Hyperglycemia - high BS, can be life-threatening. In type 1 diabetics this can result in conditions of escalating seriousness, including unconsciousness that is sometimes referred to as 'diabetic coma'. Diabetes is typically established when fasting BS > 7mmol/liter.

Hypoglycemia ? low BS, is easily solved by ingestion of sugar. It reaches the blood ? to be transported about the body - most quickly in liquid form such as juice or fluid replacement drinks.

Hypo-/hyper-glycemia cannot always easily be distinguished. They can be quickly recognized by abnormal lack of awareness, lack of ability to reason or sudden moodiness or crankiness (think of your otherwise kindly swimmer going jeckell-and-hyde on you.)

Insulin is the hormone that helps regulate our BS level. In normal individuals, it is manufactured in our body (in the pancreas) and when present, sends a signal to the cells in our body to open their doors and let the glucose for immediate use or to be placed in their storage chambers so we've got energy reserves for later. In diabetics, insulin is either not produced in adequate quantity or at all, or it is present but not recognized by the cells, a condition known as insulin resistance.

Glycemic index describes the relative speed of absorption of a carbohydrate after it is eaten. Diabetics pay attention to this as eating meals with overall low glycemic index helps avoid sudden spikes in BS levels. In cases of hypoglycemia, a high-glycemic index food is needed quickly.

Diabetics can also experience polyuria (excessive urination) which can play a role in producing a dehydrated athlete and polydypsia (excessive and prolonged thirst) which will not necessarily help with rehydration due to excessive sweating.

ACSM is the American College of Sports Medicine.

The effect of Diabetes on ability to exercise

Individual responses to exercise varies, and experts suggest measuring BS before, immediately after, and several hours after bouts of exercise until the individual's pattern is clearly demonstrated. Low BS will weaken the swimmer; high BS can be dangerous. Monitoring is critical during exercise, particularly when the swimmer begins to feel unwell or demonstrates reduced focus.

Moderate and vigourous exercise are recommended for at least 30 minutes most days of the week (minimum 3 days per week, but never taking more than one day off consecutively because of the diminishing effect of time on post-exercise BS control.) Strength training increases the body's lean muscle mass, improving its metabolic profile, or how the body uses energy. It is also recommended for diabetic individuals, although a review of complicating factors is necessary ? e.g. reduced circulation in legs requires care to be taken with weight-bearing exercises; excessive power training and in particular the val salva manoeuver is not recommended for an individual with retinopathy (a common complication.)

Type 2 diabetes is often observed in obese individuals, for whom the most important objective should be to reduce body weight, as additional weight further increases insulin resistance in these individuals. Weight loss is a function of calories burned minus calories consumed ? so coaches have a role to play. They can help by considering the total calories burned in practices ? and telling swimmers they may need extra work when practice is less energy-consuming for any reason. They can also suggest exercises to increase the body's muscle mass, as bigger muscles mean increased metabolism even when the body is at rest. It is also helpful for the coach to help manage expectations ? it is common in type 2 diabetics to be unable to sustain high-intensity exercise. This means agressive weight loss objectives may be unrealistic in the short term without pharmaceutical intervention (the doctor's job.) Coaches can help the swimmer celebrate ongoing success during steady, long-term weight loss.

There is a difference in response to very high intensity exercise and lower intensity aerobic sets. For Type 1 diabetics who experience acute hypoglycemia (a sugar crash) after 20 minutes of aerobic exercise, a simple solution is suggested by some relatively new research ? a 10-second maximal effort. Studies show these sprints elevate BS levels and provide a good alternative to administering additional sugar or other medicinal interventions. Both moderate and high-intensity exercise are effective at improving the body's ability to produce insulin in type 1 diabetics ? confirming that high-intensity exercise will not reduce the benefits of exercise, although longer recovery periods may be needed. However, complicating health issues such as cardiovascular disease must be considered before asking the swimmer to sprint as a method of increase BS.

In the case of extreme hyperglycemia over 16.5 mmol/liter in type 1 diabetics, exercise is not recommended until BS is lowered. For type 2 diabetics, this precaution appears to be unncessary although the intensity level should not be high until BS is reduced.

In type 1 diabetes, 'ketoacidosis' results when the body is no longer able to access sugar sources (though they are usually present) and begins to break down stored fat ? but without insulin, the process spins out of control (a similar response can occur in individuals with advanced anorexia.) One of the byproducts is acetone ? the chemical in nail-polish remover. If coach or lane-mates notice this smell on the breath of a diabetic swimmer, an intervention is in order, as this state is often accompanied by dangerous hyperglycemia, dehydration, and high acid content in the blood.

The exercise strikes back: its effect on Diabetes

In general, the body's metabolism is normalized by exercise ? which simply means it maintains a more steady rate of burning energy. This effect is especially desirable in a diabetic and explains why frequent exercise is a top priority for a diabetic.

The ACSM notes the role played by aerobic exercise in improving our body's ability to process and deliver sugar to working muscles. How? Regular exercise reduces insulin-resistance, and helps muscles receive sugar more readily. Some interesting research is showing that type 2 diabetics with insulin resistance are still able to reduce blood glucose levels through a generalised exercise response. (Think of these 2 pathways as 2 doorways for the glucose to take into the same room, which is the muscle cell ? once it's in the cell and being used as a fuel source, it's one less glucose molecue hanging out in the blood.) The pharmaceutical industry is studying this effect, hoping to someday develop a drug that mimics exercise.

Studies are beginning to show that a diabetic with vascular complications will not trigger the same increased blood flow to working muscles. This means there is a double-edged sword: less oxygen delivery is possible on top of the reduced glucose uptake. Larger studies are being conducted to deepen understanding in this area. Training implication: a diabetic with known reduced circulation should be prepared to be limited to training at lower intensities.

Research is showing an increasing link between diabetes and the development of mood disorders such as depression, which gives another argument in favour of frequent endorphin-releasing exercise for our swimmers with diabetes.

Best practice for a diabetic swimmer ? eating and training

Diabetic swimmers should discuss their own BS profile with their doctor to determine when to eat before practice, and how to modify their insulin intake if necessary. Lower glycemic index foods are a good choice before training, and a sugar solution during extended practices.

A source of sugar (and insulin if applicable) should always be kept on deck during training when a swimmer is diabetic. Coaches, lifeguards and lanemates should be made aware of the condition and share an action plan.

Scientists have demonstrated that the metabolism (the body's rate of using energy) remains elevated for up to 24 hours after exercise.) This suggests that it is a good idea for a diabetic swimmer to swim daily ? and to be sure to have a long recovery set after a sprint raises BS levels, making cool down essential at meets as soon as possible after a race, and extending the aerobic and cool down portions of practices with speed training.

Hypoglycemia in non-diabetic individuals

It is not common, but we can observe the symptoms of hypoglycemia in some non-diabetic athletes during exercise even if they did not skip a meal. This typically happens because the individual ate too close to the beginning of practice, stimulating their body to release insulin. The result: the athlete starts the practice with crashing BS because of their overly enthusiastic insulin response. The solution: susceptible individuals should eat a low glycemic index meal at least 45 minutes and not less than 2.5 hours before training, and then fast until practice begins.

The coach's role

Recruitment tip: swimming is a great sport for type 2 diabetics who have begun to experience a loss of sensitivity in their lower limbs, making it too risky for them to play certain land sports because they can't tell if they are doing damage. Our low-impact, no falls sport of swimming is a great alternative. Speak to a local clinic and/or doctors near your pool to let them know your masters program has room to welcome a new swimmer! The good news: recent studies show that exercise tends to limit development of this neurological dysfunction.

Swimmers: carry your glucometer to the pool and tell your coach what's going on so they can help you monitor your response as well as suggest modifications to sets until you have your BS under control.

Another role for coaches is in helping to educate their swimmers. Many diabetics have trouble adhering to nutrition regime, sometimes because of a lack of understanding, sometimes because it is too different from their habits. A coach who takes a holistic approach can help diabetic swimmers by proactively asking them what they ate before practice, what they'll eat after, reminding them to use their glucometer to measure their blood sugar as appropriate, will encourage their swimmers to stay the course to better health.

Can a diabetic still train hard?

Yes! A cautious beginning is prudent for anyone new. The fitter the individual and the more carefully they monitor and control their BS level, the greater will be the emphasis they may place on performance.

Author Robyn Ouimet is a Phys.Ed/Kinesiology graduate of McGill University and a Masters swimmer and coach. She thanks fellow swimmer Dr. Ann Walling for reviewing this text. Robyn's teammates spread rumours that she has so much fun in practice because that orange fluid in her water bottle is actually a screwdriver and not the sugar drink she claims to need to counter her own tendency toward hypoglycemia. She can be reached at robyn.ouimet@gmail.com.

Links

http://www.diabetes.ca/
Includes useful information about diabetes management, and glycemic index charts and recommendations

http://www.diabetes.org
American Diabetes Association

Http://www.acsm.org
American College of Sports Medicine web site ? plenty of scientific and clinical recommendations.

http://care.diabetesjournals.org/
Journal publishes articles about diabetic research.

http://www.joslin.org./
A diabetes research center at Harvard University. Research from various perspectives.

http://en.wikipedia.org/wiki/Diabetes
The wikipedia page on diabetes has statistics and information in layman's terms.