DIABETES AND EXERCISE

S L Jones

VO2 maxA MEASURE OF AEROBIC FITNESS

• VO2 max maximum volume of O2 consumed by the body each minute during exercise

• Measure of aerobic work capacity• < 45 ml/min/kg in untrained, >80 ml/min/kg in

Olympic athlete.• Heart rate is used as a marker• Max HR = 220-subjects age

AEROBIC AND ANAEROBIC EXERCISE

• Aerobic, – O2 delivery is sufficient, allowing complete oxidation of glucose and

fats

• Anaerobic – when O2 requirement rises above delivery– Anaerobic exercise is limited by lactate accumulation in muscle

• Lactate threshold • ~60% VO2 max in untrained • higher after training

• HR – below 65% max – exercise is aerobic, – @70-85% max (standard training zone) = mixed aerobic and

anaerobic

TO IMPROVE OR MAINTAIN HEALTH

• Metabolic improvements are seen with low to moderate intensity exercise (40-75% VO2

max)• Favourable changes in glucose tolerance and

insulin sensitivity deteriorate within 72 hours of physical activity

• Recommendations– 30 minutes of moderate intensity exercise – 60-79% max HR or 50-74% V02max – At least 3 days of the week

EXERCISE TO ASSIST WITH WEIGHT MANAGEMENT

• Weight loss is easier if the exercise undertaken is of – Lower intensity for a longer duration

• 40-70% V02max for 60 minutes

• May be divided into 2 or 3 periods of shorter duration

– More often• Undertaken 5 or more days of the week

TO IMPROVE OR MAINTAIN CARDIOVASCULAR FITNESS

• Increased oxygenation demands of muscle are met by increased cardiac output (stroke volume and HR) and respiratory effort

• The effect of aerobic training is to increase VO2 max

• Recommendations– 20-60 minutes of moderate to high intensity exercise – 60-90% max heart rate or 50-85% V02max – Minimum 3 times a week

ADVANTAGES OF EXERCISE

IMPROVED VO2 max (from aerobic exercise)• Increased insulin sensitivity• Reduced cardiovascular risk factors such as increased

HDL and reduced LDL• Enhanced fibrinolysis• Improved psychological status• Increased muscle mass and reduced fat mass.

ANAEROBIC EXERCISE (impact/resistance)• Increased muscle strength and endurance and lean body

mass

The Athlete with diabetes

Expectations have risen

• High profile sports persons– Steve Redgrave

– Gary Hill Jnr

– Rod Kafer

• Improved insulin delivery regimes

Considerations

• Physiological changes

• Metabolic changes

• Risk of ketosis/hypoglycaemia

• Risks of injury (RSI)

• Effects of diabetes complications

– especially cardiovascular, autonomic neuropathy

• Effects on diabetes complication

– Retinopathy, nephropathy and foot problems

Maximum heart rate and the likely effect on blood glucose

% Max HR Training zone Typical Exercise

Effect on blood glucose

< 60 Non-training Walking LittlePossible small fall

60-70 Mostly aerobic Jogging, swimming

Falls after 20-30 mins

70-85 Mixed Running, football, rugby

Steady and marked fall

>85 Anaerobic Sprint, squash Rising blood glucose

AEROBIC EXERCISE• ATP is used in muscle

• Initially ATP is regenerated by phosphate from intracellular phosphocreatine stores

• Intramuscular glycogen is then used in initial stages of exercise

• Subsequently stores are replenished by oxidation of intracellular glucose– Glucose is taken up from blood stream (promoted by insulin)

– Produced by hepatic glyconeogenesis, hepatic and renal gluconeogenesis

– (Medicated by glucagon, catecholamines and growth hormone {stress hormones} in presence of low insulin levels)

AEROBIC EXERCISE continued

• The stress hormones mobilise fat from adipose stores – mostly subcutaneous– Triglycerides are used directly by muscles (as free fatty acids) – or metabolised to ketone bodies by the liver which are then

metabolised in the muscles.

• In prolonged exercise if the partial pressure of O2 remains

high enough oxidation of ketones becomes the preferred fuel source

• The more intense the exercise the greater reliance on carbohydrate

ANAEROBIC EXERCISE

• ANAEROBIC – INTENSE EXERCISE– ATP-Creatine – lasts 6-8 secs before depletion

– Muscle glycogen is subject to anaerobic glycolysis – with lactic acid production as by-product

– If lactic acid accumulates faster than can be used by the liver it builds up and limits exercise

– Stress hormones are released which encourage gluconeogenesis and hepatic glucose output and together with insulin resistance this produces post exertional hyperglycaemia

PHYSICAL TRAINING

• Builds capacity for aerobic metabolism by increasing lung function, cardiac output and tolerance to lactate

• Results is less of a stress hormone response – so less glucose production and glycogenolysis and better use of fat– There is then a reduced risk of hypoglycaemia and a lower

requirement for carbohydrate snacks during the exercise.

• Limitations– O2 supply by cardiovascular and respiratory systems– Quantity of fuel stored as glycogen in the skeletal muscles– Capacity for gluconeogenesis and mobilisation of fat stores.

• THE NORMAL RESPONSE TO EXERCISE IS TO– Reduce insulin– Increase stress/counterregulatory hormones

such as adrenaline, noradrenaline, cortisol, GH and glucogon

INSULIN LEVELS

• Will depend upon time of last insulin dose

• Type of insulin – short or long acting/CSII

• Site of administration

• Rate of absorption

INSULIN LEVELS

• HIGH INSULIN LEVELS– Increase muscle

glucose uptake

– Impairs fatty acid use

– Reduces stress hormone action

– MORE RISK OF HYPOGLYCAEMIA

• LOW INSULIN LEVELS– Impairs muscle glucose uptake– Increased hepatic glucose output– Enhances stress hormone action– MORE RISK OF

HYPERGLYCAEMIA

– PLUS LESS GLYCOGEN REPLETION IF LEVELS CONTINUE LOW > 1HR POST EXERCISE

– MEANS FUTURE EXERCISE IMPAIRED

Young adult with Type 1

• Cardiovascular and respiratory responses unchanged, • Non-insulin related stress hormone responses unaltered

• Problem – subcutaneous insulin administration – No portal insulin to regulate hepatic glucose output, – Supraphysiological peripheral insulin levels impair fuel

mobilisation– Insulin release from subcutaneous site - reverse of

physiological ie insulin levels are maintained or increased with exercise

Young adult with Type 1

• Mismatch between glucose utilisation and production –

– hepatic glucose output may be insufficient and glucose level falls during prolonged exercise especially at high intensity exercise where glucose is the preferred fuel

– glucose production may alternatively exceed use where periods of intense exercise are short or the subject unfit and glucose levels paradoxically rise

• Post exercise – insulin release is unavailable to balance the effects of

exercise induced catecholamines, growth hormone and glucogon resulting in post prandial hyperglycaemia

• In the later post exercise period – diabetics are prone to hypoglycamia

ALSO• Hypoglycamia following exercise

– more likely with pm than am exercise

– more likely with lower limb aerobic exercise

• Be aware that increased absorption of insulin could occur when injecting into leg if followed by exercise

• Need to integrate– Training and event plans– Food intake– Basal and bolus insulins– Frequent blood glucose monitoring

• Attention to choice of injection site and technique (not im!)

• Suggest basal bolus or CSII (if pump not in the way)

Pre exerciseReduce insulin, increase carbs – but best balance is adjustment of both ie restrict excess carbohydrates and reduce insulin 40-50% so less hyperglycaemic at start and less fall in glucose during race

During exerciseNeed rapidly available carbs eg glucose up to 1g/kg/hrsports drinks contain around 6g/100mlwith some Na and K

Higher carb drinks 15g/100ml if needed to replace quickly while restricting fluidCan buy powdered drinks to make up to requirements - maltodextrin

Post exerciseInsulin with snack or meal to replenish muscle and liver stores of glycogen eg 60-120g

Suggested changes in premeal insulin dose before aerobic exercise

Intensity of exercise%VO2max

Max HR (%) Duration Minutes

Suggested reduction

Glucose intake during exercise

50 <70 60 50% None

50 70-80 30 50% 30g

50 70-80 60 75% 30-60g* if longer than 1 hr this amount/hr

70 >80 60 90% 30-60g* if longer than 1 hr this amount/hr

75 >80 30 75% 60g

• You should not exercise if glucose is above 17mmol/l {risk of ketosis}

• Be aware that the effects of activity may last for many hours after exercise

• If you exercise again with in 48 hours of previous exercise there is more chance of hypoglycamia

CARBOHYDATES

• Combinations of short and long acting may be needed– Eg sips of short acting or occasional long acting such as

cereal bars, bananas

• Carbohydrate loading is practiced by athletes for 3-7 days prior to duration events– Those with diabetes will need to increase insulin to

match the increase carbs and reduced exercise of this period (protein will also be needed in the post exercise period)

DON’T FORGET THE FLUIDS

• Drink enough to prevent dehydration– Dehydration reduced ability to perform

– By the time you feel thirst you are already dehydrated

• Suggest– 500 ml before starting exercise

– 500ml/hr during exercise – as frequent sips

– More if the weather is warm

• Carbohydrate and fluid intake can be combined eg as sports drinks (check concentration). Solutions of concentration > 10% empty slowly from the stomach and are more appropriate before and after rather than during exercise

DON’T FORGET THE RATHER MORE BASIC ADVICE

• Monitor blood glucose levels more frequently, before, during and after activity

• Encourage person to ensure friends / colleagues aware of diabetes (risk of hypo)

• Remember that glucose may fall later in the day after exercise and adjust long acting insulins and may need prebedtime snack

• If person increases fitness +/- loses weight due to increase activity levels, ‘regular’ insulin doses will probably need reducing

SPECIAL CONSIDERATIONSRETINOPATHY• In theory physical exercise could have a potentially detrimental effect

on retinopathy through elevation of systolic blood pressure during the activity.

– But no evidence for this

• Wisconsin epidemiological study of DR, higher levels of physicial activity were associated with reduced risk of proliferative retinopathy in women.

• Bernbaun, 12 week moderate intensity exercise programme – no deterioration in retinopathy

• Bernbaun M, Albert S, Cohen J et al. Cardiovascular conditioning in patients with diabetic retinopathy. Diabetes Care 1989:12;740-742.

• Encourage low impact aerobic exercise

– such as walking, swimming, cycling

• Discourage strenuous exercise,

– such as that involving Valsalva-type manoeuvres or jarring

– those than increase intraocular pressure eg scuba diving

– those that lower the head below the waist.

PERIPHERAL NEUROPATHYLemaster 2 yr study in those with previous foot ulcers

• Those most and moderately active had less risk of recurrence than those least active

• INSENSATE FOOT• Recommend care with weight bearing exercise • eg prolonged walking, running, steps• Suggest cycling, rowing, swimming, chair exercises• Eliptical walkers reduce foot strikes• Ensure good foot care and appropriate foot wear (silicone insoles)

• Lemaster J, Reiber G, Smith D et al. Daily weight bearing activity does not increase the risk of diabetic foot ulcers. Med Sci Sports Exerc 2003:35;1093-99.

AUTONOMIC NEUROPATHY• Associated with reduced aerobic capacity and increased risk of

adverse cardiovascular events or sudden death during exercise• Abnormal heart rate response (so do not rely on this to determine peak

exercise), abnormal blood pressure responses, postural hypotension, ventilatory reflexes impaired – increased respiratory rate and alveolar ventilation in response to submaximal incremental exercise

• Difficulty maintaining body temperature and hydration

• Avoid exercises with sudden change in posture• Suggest – water exercises and semirecumbent cycling

• Hilstead J, Galbo H, Christensen N. Impaired cardiovascular responses to graded exercise in diabetic autonomic neuropathy. Diabetes 1979:28; 313-319.

PERIPHERAL ARTERIAL DISEASE

• Little evidence of outcomes

• Suggest ‘interval training’ – 3 minutes walk, one minutes rest, swimming, stationary cycling, chair exercises

NEPHROPATHY

• Bp and albumin excretion rise with exercise – but is this harmful?

• Recommend

• Avoid high intensity exercise

• Encourage light to moderate intensity

• Avoid supplements

– amino acids and creatine will increase renal load

– caffeine has a diuretic action and contributes to dehydration

COLLAGEN/VASCULAR

• Tissue changes associated with glycation make the patient with diabetes more prone to overuse injury.

REMEMBER TO– Warm up– Stretch– Cool down

PREGNANCY AND DIABETES

The most comfortable exercises are those that don't require the body to bear extra weight. These include:

Swimming or water workouts Stationary cycling Walking or step machin Low-impact aerobics Yoga T’ai chi

THE PATIENTS WITH ISCHAEMIC HEART DISEASE

• Unable to assess exercise level by heart rate if on B-blockers or other rate limiting agents.

• Post MI should be on cardiac rehab program

• If major concerns may need angiography

• Be aware of possibility of ischaemia without chest pain in patients with diabetes (silent MI)

THE OVERWEIGHT PATIENT WITH DIABETES

• WEIGHT LOSS PROGRAMMES– The most successful combine the principles life style

management and change with diet and exercise

– Eg weight watchers and Rosemary Connelly diet

• DIET ALONE– GI diet, Atkins can be successful but need to combine

with active lifestyle advice for longer term success

SLOW AND STEADY

FOR OVERWEIGHT PATIENTS WHO ARE INITIALY INACTIVE

Programme of exercise will need to start slowly but increase progressivelyWarm up and cool down important

EXERCISE ON PRESCRIPTION Will hopefully guide the patient through the initial stages, encourage progressive increase in exercise and help with motivation (personalised programmes)

ADVICE

• Types – personal preference

• Intensity – comfortable level – increase towards targets with time

• Other benefits – psychological, weight– For weight loss exercise should be increased to

one hour

THE ADVANTAGES OF A 10KG WEIGHT LOSS

Mortality

Blood pressure

Angina

Lipids

Diabetes

• Total mortality decreased 20-25%• Diabetes related deaths decreased 30-40%• Obesity-related cancer deaths decreased 40-50%

• SBp decreased 10mmHg• DBp decreased 20mmHg

• Symptoms decreased 91%• Exercise tolerance increased 33%

• Total cholesterol decreased 10%• LDL cholesterol decreased 15%• Triglycerides decreased 30%• HDL cholesterol increased 8%

• Risk of developing diabetes decreased more than 50%• Fasting glucose decreased 30-50%• HbA1c decreased 15%

• Obesity is hype because it appears that it is obese peoples lack of fitness that puts them at risk

(Quoted by Roger Hawkes)

THE HOUSEBOUND PATIENT

• Depending on degree of disability– Chair based exercises

– Steps

• For patients who cannot manage longer periods of exercise it is important to inform them that multiple shorter periods eg 10 mins 3x /d can be just as good as one period of 30 minutes

METABOLIC SYNDROME

MUST HAVE• Central obesity

– >94 cm Europid male, > 80 cm Europid female

PLUS ANY TWO OF THE FOLLOWING• Raised triglyceride

– >1.7 mmol/l or specific Rx for this abnormality

• Reduced HDL-C– <0.9 in males, <1.1 in females or specific Rx for this

• Raised Bp– Systolic >130, or diastolic > 85 or specific Rx for this

• Raised FPG– >5.6 mmol/l (GTT recommended not essential for definition)– or previously diagnosed Type 2 Dm

Myers NEJM 2002

PRE- DIABETES

Prevention of Diabetes

In those with Impaired Glucose Tolerance - IGT

SIMPLE MESSAGES

• 10,000 STEPS PER DAY– Mankpo-kei – 10,000 measured steps– (now ten-K-a-day)– Used to promote the sale of pedometers in

Japan– Promoted at the Tokyo Olympics 1964– Came to the UK in 2000

CASE EXAMPLES

CASE EXAMPLES

• Runner, NR/Detemir• Usually after breakfast

– 25% reduction in breakfast NR– Lighter meal– Sips during run– Usual insulin with increase CHO for lunch

• If exercises before breakfast– Less CHO during run – just as needed– Normal insulin with breakfast after run

CASE EXAMPLES

• Football team• Both midfield player and goalie have Type 1 and

are treated with basal bolus insulin• Pre match meal

– Midfielder reduces bolus insulin by 50-75% – Goalie by 25%

• Pretraining meal– Both midfielder and goalie reduce insulin by 40% – And basal by 10%

CASE EXAMPLES

• Rower• Training – reduce insulin, more so if cold, hot or windy• Racing – check glucose pre race and give extra units if raised

anticipating further rise from anaerobic metabolism

• Tennis• Greater reduction in dose if playing singles than doubles

• Golf• Usual reduction of around 20% with snacks each hour (half banana)

but even less insulin or more snacks if caddie fails to turn up

The following sources are acknowledged

Kirk A, Fisher M, MacIntyre P

Practical Diabetes International 2004: Vol 21 (7) 267-275

Diabetes and survival post MI

Gallen I

Practical Diabetes International 2005:22;307-312

British Journal of Vascular Disease 2004; 4: 87-92.

The management of insulin treated diabetes and sport

Colberg S (Ed)

The Diabetes Athlete

Human Kinetics Leeds