Dr. Siham Gritly 1

Postgraduate Diploma in Diabetes Education (PDDE(

lec 2 Nutrition therapy: Diabetes Mellitus and physical activates

Metabolic Responses to Exercise

Prepared by Dr. Siham Mohamed Osman Gritly

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Metabolic Responses to Exercise

• During exercise, skeletal muscle is the most important tissue in the body for glucose uptake.

the contracting muscles produce their own insulin-like effect, causing the rapid uptake of glucose from the blood.

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• Other hormones such as epinephrine (adrenaline), glucagon and cortisol assess to maintain and increase blood glucose levels during exercise

• Avoiding hypoglycemia or hyperglycemia can also be achieved by increasing or decreasing, respectively, the amount of carbohydrate ingested before planned exercise

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blood glucose response to exercise will vary depending on:

• blood glucose level before starting activity,• the intensity of the activity,• the length of time you are active,• and changes you’ve made to insulin doses.• Sometimes people experience a drop in blood

glucose during or after exercise, so it is very important to monitor your blood glucose, take proper precautions, and be prepared to treat hypoglycemia

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Metabolic effects of exercise in type 2 diabetes

• During exercise, • oxygen consumption may increase by as

much as 20-fold, • To meet its energy needs, skeletal muscle uses

its own stores of glycogen and triglycerides, as well as free fatty acids (FFAs) derived from the breakdown of adipose tissue triglycerides and glucose released from the liver.

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• Muscle glycogen; is the chief source of energy during the early stages of strenuous exercise,

• with increasing exercise duration the contribution of circulating glucose and particularly NEFAs become more important as muscle glycogen gradually depletes.

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Energy fuel for exercise

• Glucose (glycolysis)

• Glycogen (glycogenlysis)

• Triglyceride (triaceylgelesrol) lypolysis

• Protein (gluconeogensis)

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Muscle glycogen store is the first source of glucose for the exercising muscle

when no glycogen;- the process of glycogenolysis started and follow by gluconeogenesis in the liver to make glucose available (main function of the liver is to release glucose through glycogenolysis and gluconeogenesis )if no enough glucose after 3 hours of heavy exercise athletes enter to a condition known as hoypglycemia (low glucose level in the blood)

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Oxidative metabolism and anaerobic metabolism are both used for provision of

energy during exercise• Adenosine triphosphate (ATP) is the principal high-

energy phosphate molecule that enables muscle contraction (immediate energy sources).

• Phosphocreatine (PCr) is another high-energy compound containing a high-energy phosphate bond that can be hydrolysed to provide energy and resynthesize ATP:

• Oxygen delivery during strenuous exercise is limited by cardiovascular function.

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immediate energy for exercising muscles

• immediate energy - used in first 10-30 seconds of vigorous exercise; ATP creatine phosphate (ATP-CP) system used;

creatine phosphate contributes a phosphate to ADP to make ATP; 1 creatine phosphate (CP) = 1 ATP;

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short-term energy for exercising muscles

• short-term energy - used approx. 30 - 90 seconds into vigorous exercise;

• uses glycolysis to break down glucose to

pyruvate to lactate (lactic acid);

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long-term energy for exercising muscles

• long-term energy - used approx after 2 min of vigorous exercise;

• uses glycolysis, citric acid cycle (kreb’s cycle), and electron transport chain to fully oxidize glucose;

• 1 glucose = 36 ATP (max);

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Low- to moderate-intensity aerobic exercises that can be sustained for a long time (more than 20 minutes) use some glucose, but more fat for fuel.

fat providing energy during exercise that occurs at a lower intensity but not adequate for high intensity exercise such as sprints

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Unlike glycogen stores, the body’s fat stores can usually provide more than 70,000 kcalories and fuel hours of

activity without running out.Abundant energy from the breakdown of fat can

come only from aerobic metabolism.

during low-intensive exercise, fatty acid (FA) oxidation contributes considerably to total energy provision for hours or even days as long as there is sufficient oxygen to allow fat metabolism to occur

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Major body systems and Metabolic Responses to Exercise

• Endocrine response to exercise;

• Response of the Cardiovascular System to Exercise

• Response of the Skeletal System to Exercise

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Endocrine systemthe endocrine system is a system of glands, (ductless) each of which secretes a type of hormone. hormone is directly released into the bloodstream to regulate the body functions. field of study dealing with the endocrine system endocrinologyHormones are secreted by a variety of glands in response to altered conditions in the body. Each hormone travels to one or more specific target tissues or organs, where it elicit a specific response to maintain homeostasis

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• Hormones regulate various human functions, including;

• metabolism,

• growth and development,

• body tissues (the physical and chemical processes of the body),

• sexual development and function

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The major glands of the endocrine system

the hypothalamus, (link the nervous system to the endocrine system via the pituitary glandpituitary, (secretes nine hormones that regulate homeostasis) thyroid, parathyroids,adrenals, pineal gland, (melatonin that helps to regulate sleep/wake)the reproductive organs (ovaries and testes). The pancreas; insulin and glucagon

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Response of hypothalamus to blood glucose level

The hypothalamus is a part of the brain involved in the control of involuntary activity in the body; contains many centers of neural control such as temperature, hunger, appetite and thirst

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• Most hormones are secreted from the glands that produce them under the influence of stimulating hormones from the hypothalamus.

• These hormones in turn are activated by releasing hormones from the pituitary gland

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1-Endocrine Response to Exercise

• Many hormones play a role in physical exercise; the endocrine response to exercise can improve organ function, physical fitness and overall psychological state.

• without hormones, exercise would be limited. • Vigorous exercise, in particular, might

improve endocrine function.

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Hormones important in physical exercise

• Hormones important in physical exercise include;

1-testosterone from the testes,

2-norepinephrine or adrenalin and cortisol from the adrenal glands

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3- thyroxin from the thyroid gland

4- human growth hormone -- also called HGH or somatotropin -- from the pituitary gland.

5-insulin and glucagon from the pancreas,

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Functions of Insulin during and after exercise

1- Stimulation of glucose uptake into most cells of the body,

2- Inhibition of glucose release from the liver,

3- Inhibition of the release of fatty acids from storage tissue,

4-Facilitation of protein synthesis in the body's cells,

5- Stimulation of the re-synthesis of muscle glycogen after exercise

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2-Response of the Cardiovascular System to Exercise

• The heart is a muscle that is required to contract continuously throughout the life to deliver oxygen to all organs in the body and breathe out carbon dioxide

• Blood vessels connect the heart and lungs so that carbon dioxide can be removed from the blood and oxygen can be added to the blood.

• The heart then pumps this blood throughout the body.

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• Exercise places an increased demand on the cardiovascular system to pump more oxygen to supply the working muscle to produce energy (aerobic oxidation).

• Oxygen demand by the muscles increases, more nutrients are needed and more waste is created.

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The heart is a four-chambered organ consisting of right and left halves. Two of the chambers, the left and right atria, are entry-points into the heart, while the other two chambers, the left and right ventricles, are responsible for contractions that send the blood through the circulation. The circulation is split into the pulmonary and systematic circulation. The role of the right ventricle is to pump deoxygenated blood to the lungs through the pulmonary trunk and pulmonary arteries. The role of the left ventricle is to pump newly oxygenated blood to the body through the aorta

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Functions of The Cardiovascular System during exercise

The cardiovascular system serves five important functions during exercise:

• 1- Delivers oxygen to working muscles2- Deoxygenates blood by returning it to the lungs3- Transports heat from the center to the skin4- Delivers nutrients and fuel to active tissues5- Transports hormones

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Cardio-respiratory endurance

Cardio respiratory endurance is the ability of the body’s circulatory and respiratory systems to supply fuel during sustained physical activity”Cardio-respiratory endurance; is the amount of oxygen individuals are able to take in and oxidized it for energy production to be used for working muscles

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benefit to increases cardio respiratory endurance

• the most important benefit to increases cardio

respiratory endurance is an increased VO2max which

is the body’s ability to deliver oxygen and nutrients to

the cells, lead to;.

• Lower risk of heart disease

• Reduced Risks of type 2 diabetes

• Lower Blood pressure

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The skeletal system consists of;bones, ligaments and tendon

bones, ligaments which connect bones to other bones and cartilageTendons connect muscle tissue to bone and although more elastic than ligaments, have a greater strength than muscle

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Four basic functions of skeletal system

• The skeletal system comprises of 206 bones and provides four basic functions:

• Support for tissues and muscle• Protection for vital organs• Movement through bones and attached

muscles• Storage for minerals and immature blood

cells

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Effect of exercise on the skeletal system

• Exercise may improve to maintain healthy bones• bone responds to mechanical stresses. When

mechanical stresses are applied, more mineral salts are deposited and more collagenous fibres are produced.

• The physiological response to exercise is dependent on the intensity, duration and frequency of the exercise as well as the environmental conditions.

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• During physical exercise, requirements for oxygen and substrate in skeletal muscle are increased, as are the removal of metabolites and carbon dioxide.

• Chemical, mechanical and thermal stimuli affect alterations in metabolic, cardiovascular and ventilatory function in order to meet these increased demands

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skeletal muscle is powered by one and only one compound... adenosine triphosphate (ATP. However, the body stores only a small quantity of this 'energy currency' within the cells and its enough to power just a few seconds of all-out exercise. So the body must replace or resynthesize ATP on an ongoing basis

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References • American Diabetes Association (2002). Clinical Practice

Recommendations:2002. Diabetes Care 25 (suppl. 1):S64-S68.• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and

Human Metabolism, fifth ed. WADSWORTH

• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw Hill

• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999.

Modern Nutrition in Health and Disease; Shils E Maurice, Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th edition

• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition, W.B. Company

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• Sigal RJ, Kenny GP, Wasserman DH, Castaneda-Sceppa C. 2004. Physical Activity/Exercise and Type 2 Diabetes. Diabetes Care 27: 2518-2539.