1. health and fitness
2. exercise

DIABETES AND EXERCISE
S L Jones
VO2 max
A 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
Little
Possible 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 exercise
Reduce 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 exercise
Need rapidly available carbs eg glucose up to 1g/kg/hr
sports drinks contain around 6g/100mlwith some Na and K
Higher carb drinks 15g/100ml if needed to replace quickly
while restricting fluid
Can buy powdered drinks to make up to requirements - maltodextrin
Post exercise
Insulin 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 CONSIDERATIONS
RETINOPATHY
• 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 NEUROPATHY
Lemaster 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 Bblockers 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 progressively
Warm 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