This information is aimed at people with diabetes who participate, or would like to participate, in sports such as cycling, swimming, long distance running and weight training.
Getting started
Training for any event that involves sustained activity, whether for longer than an hour or in short intense bursts, involves adaptation and management. All athletes find that training and competing affects them differently, and those with diabetes find that learning how diabetes is affected by activity is an important part of the process.
- If you have had diabetes for a long time or are over 35, you may wish to ask your GP for a physical examination before you start a training programme. If you usually see a diabetes care team, discuss your plans with them.
- People with diabetes can be prone to foot and circulation problems. You need to ensure you are wearing appropriate footwear for your activity. For example:
If you are cycling – visit a specialist cycling shop.
If you are running – visit a specialist running shoe shop for computerised analysis to find the best footwear for you, or contact a running club for advice.
- Check your feet after exercise and watch out for blisters and discomfort. See a state-registered chiropodist if you develop any problems. Don't use methyl salicylate or any medication that contains a localised painkiller because this can mask any problems.
- When swimming – keep moving whilst in the water. Cramps can occur after a short rest in cold water, usually coming on with the first strong kick off when restarting. Dry off quickly when you finish – don't hang about getting cold.
- If you are training seriously for outdoor sports you are likely to have to exercise in the cold and the wet. No gear is completely water or windproof, but wearing appropriate clothes can change an unpleasant experience into a great achievement. Choose fabrics that keep moisture away from your skin and don't get heavy when wet. Any sportswear shop will be able to advise you.
- Build up your times and distances slowly (adding five to ten minutes every week to your training program, for example). There are lots of books and magazines to follow, or you could join a club and adopt a sensible training programme that is right for you. Aim to train three to five times a week.
- When training, you may find it useful to carry a 'bumbag', small rucksack or a plastic container such as an ice-cream carton that contains a blood glucose testing kit, identification, money for emergencies, food, glucose tablets, drinks, etc. Cyclists may wish to get a bag that attaches to their saddle.
Insulin doses
- Regular exercise increases insulin sensitivity. Endurance athletes who treat their diabetes with insulin may sometimes reduce the amount of insulin they inject while training. Because insulin is absorbed more rapidly from sites involved in physical activity, before exercising it is best to inject into a site not especially taxed in your activity (the stomach, for example). It is important to discuss your medication with your diabetes care team, who will advise you on the most appropriate treatment and any changes that need making to your normal regime.
Blood glucose monitoring
Testing your blood glucose levels before, during and after a training session requires a blood glucose meter that is easy to use while exercising. Keep a record of your readings in a training log, and record details of the distance and time of the session, the food eaten and insulin doses taken so that you can establish a pattern of likely insulin needs and glucose requirements for future sessions. You may also like to discuss these with your diabetes care team.
Depending on the results of your pre-activity blood glucose test, you may well need to eat some starchy carbohydrate food before you start. If the test shows that your blood glucose level is 13mmol/l or above, you must also test for ketones (test strips are available from your GP). Even if ketones are not present, there may still not be enough insulin for your muscles to be able to mobilise the energy needed to exercise. Your blood glucose level will rise further as a response to the activity and yet, without insulin, still not provide the muscles with energy. Delay the training session until your insulin has taken effect and your blood glucose level has come down.
If ketones are present, this indicates that fat is being metabolised for energy. If a positive ketone test accompanies a high blood glucose level, this may be a sign of ketoacidosis and you should seek medical help immediately.
It is important to realise that your body takes up to 36 hours to recover from sustained activity. The process of muscle refuelling will continue to use up any carbohydrate that is eaten until the muscles are replenished. Be aware of the risk of hypos – not only overnight but also the following day. Have a bedtime snack and monitor your blood glucose level when you wake.
Foods and fluids
The healthy balanced diet recommended for people with diabetes is also the diet recommended for athletes. However, you will probably find that you need to increase your portions of starchy carbohydrate foods at all meals and snacks during the training period, as well as reducing your insulin dose. Eating plenty of starchy carbohydrate foods not only helps prevent hypos, it also helps replenish stores of energy in the muscles after each training session. Research suggests that eating a combination of protein and carbohydrate increases the uptake of muscle glycogen, while food eaten within two hours of activity promotes maximum intake into the muscles and liver. Muscles that are well nourished are less prone to injury and more responsive to training, so it is worth adjusting your eating times to fit in with your next training session.
During any training session lasting more than one hour it is important to take more carbohydrate and fluids. Fluids which also contain carbohydrate are useful, eg fruit juice and squash, or isotonic sports drinks. During a long or strenuous ride, eat more carbohydrate snacks, such as sports bars, cereal bars, chocolate or bananas.
If you have been swimming – you may feel hungrier afterwards than you would do had you done some other kind of sport. This is because of the extra calorific effort involved in maintaining body temperature, whilst also using calories to produce energy. Having a carbohydrate snack straight after swimming can begin the resynthesis of muscle glycogen that is necessary to keep you in good condition.
Drink plenty of water during and after the training session. Thirst is a sign of dehydration. Drink small amounts frequently, even if you are not thirsty – approximately 150ml of fluid every 15 minutes – because dehydration dramatically affects performance.
Isotonic sports drinks, eg Lucozade Sport or Boots Isotonic, describe a wide range of products that usually contain water, sugar, and electrolytes and, typically, 5-8 g carbohydrate per 100 ml. Isotonic sports drinks contain quickly absorbed carbohydrates which can help to give the blood glucose level a boost during sustained exercise. Sports drinks do not cause delayed stomach emptying or stomach cramps and can be used before and during a race. This is in contrast to drinks with more than 8g of carbohydrate per 100 mls, which can cause stomach cramps and slow down fluid absorption due to their effects of delaying stomach emptying. These drinks, eg Red Bull, Purdeys, Lipovitan,B3 and Power House, are not recommended.
Warming up
If you are already used to exercising intensively for 30 or 40 minutes continuously, then you will know the importance of warming up. Warming up is important to increase the amount of oxygen in your lungs, to prepare your muscles for heavier work and to loosen the joints.
When swimming – start with loose fluid strokes and a range of different swim strokes to prepare the body thoroughly, before beginning the serious training after five to ten minutes.
Stretching and cooling down
Stretching after exercise prevents injury and returns shortened muscles to their resting length. While many people stretch before and after exercise, recent research suggests that stretching before activity can be counterproductive. However, if you are recovering from an injury, stretching after you have warmed up, as well as at the end of the session, will alert you to any undue tightness and aid the process of lengthening scar tissue. Stretch the relevant muscles for ten seconds, relax and repeat.
For swimming – the most important stretches are the pectorals, the shoulder girdle, the calf muscles, the hamstring muscles and the quadriceps muscles.
For cycling and running – the most important stretches are the achilles tendons, the calf muscles, the hamstring muscles, the quadriceps muscles and the gluteus muscles (buttocks). But don't forget to stretch the triceps and shoulder girdle as well.
Training advancements – cross training
Varying the activities you try and alternating them with weights, circuit training and aerobics can dramatically increase fitness. It will help to train complementary muscles, maintain cardiovascular fitness and give your joints and bones a welcome rest. Variety also helps to prevent burnout, and if you are a swimmer they will also give your skin a break from salt or chlorine.
Speed training
If you have a specific target, speed training can help you go faster, and more efficiently.
When cycling – to get the most out of a session, freewheel for about ten minutes before and after speed work and treat hill workouts the same. Once a week find a hill that takes between 30 and 60 seconds to cycle up. Cycle up, freewheel down and repeat six to 10 times. Warm up and cool down for 10 minutes.
Injury prevention
Two main things cause injuries: overuse of muscles and biomechanical imbalance. Injuries due to overuse of muscles can be avoided by a gradual build-up in training and sufficient recovery afterwards. Injuries resulting from biomechanical imbalances should be treated at the source. Speak to your GP. If you recover from symptoms and don't address the cause, the body may overcompensate and develop a chronic condition. Follow the points below to try to keep free from injury.
- Warm-ups and cool-downs are an essential part of training, not just to get the best out of the workout but also to adapt the muscles for work without risking strain or future injury.
- Some of your training will be intense, either in duration or in the amount of energy you use. All intense training needs recovery, but not necessarily complete rest. Use other forms of training such as running, weight training, swimming and circuits to build strength and power.
- The body builds up strength and stamina best when the build up is done gradually. For example, if you can currently cycle or run five miles but need to get to ten miles, you need to progress in gradual stages. The same applies if you can currently swim for 30 minutes but need to swim for one hour.
- Always increase weights, repetitions and aerobic activity in progressive stages. Ligaments and tendons are slower to adapt than muscles, and joint pain may be a sign of 'too much too soon'. If in doubt about an injury, speak to your GP about a referral to a qualified sports therapist.
- Over-training is the major pitfall for all endurance athletes. To avoid this, divide your training schedule into weekly stages. Do three weeks of building up the distance, speed or the number of times you train, and have an easier fourth week in which you effectively go back to the starting point of the month's training. This will speed up your fitness, recovery and performance.
If you are doing circuits or weights – spread your workouts through the week, with 24 to 36 hours rest between. The muscles need time to adapt and yet will start to lose tone after 48 hours. If you are active every day, have a rest or a light day once a week.
Injury treatment
Prompt treatment for any pain or injury is imperative to keep you training. The acronym RICE reminds us to:
Rest the injured body part.
Ice it for up to ten minutes, as soon as possible, to reduce inflammation and pain.
Compress the injured body part with a firm bandage, taking very good care not to cut off the circulation (especially if you have neuropathy or peripheral vascular disease).
Elevate the injured limb to prevent further inflammation.
If the injury came on gradually it may have been caused by overuse or by a biochemical imbalance. Get a qualified assessment of the cause of the injury. After you have taken any time off, restart gradually and avoid intensive training until the injury is completely recovered.
Organised events
- Establish if the event organisers have laid on feeding stations and blood glucose testing facilities. If not, you may need to equip friends and relatives with provisions and place them at strategic/accessible points.
- Eat plenty of starchy carbohydrate foods the day before the event.
- Towards the end of the event or just after you finish, your blood glucose level may start to rise and you may need to take a small dose of fast-acting insulin to counteract this. You should discuss how to make insulin adjustments with your diabetes care team before the event.
- Take particular care if the event is at a different time of day to your normal training cycle. Your insulin requirements may vary considerably. It is best to spend at least two weeks training at the same time as the proposed event to highlight any differences.
- Follow the event organisers' instructions regarding medical conditions. For example, record details of your treatment with the event organisers or wear identification jewellery. Ensure that an official knows about your diabetes. It could save your life.
Further information
Sports Dietitians UK (SDUK) is a specialist group of the British Dietetic Association for HPC Registered Dietitians who specialise in the field of sports nutrition.
SDUK aims to provide up to date sports nutrition information based on sound scientific principles for both the general public and health professionals.
Sports Dietitians UK (SDUK) c/oBritish Dietetic Association
5th Floor, Charles House
148/9 Great Charles Street Queensway
Birmingham
B3 3HT
Tel: 0121 200 8080
Website: www.sportsdietitians.org.uk.
For further information about sports and diabetes visit www.runsweet.com.