the body and exercise

Question 1

describe the aerobic energy system

Answer 1

• prolonged exercise (marathon, not high intensity)
• lower intensity (slow-twitch muscle fibres)
• requires oxygen (mitochondria)
• glucose and glycogen (liver), adrenalin causes release of glycogen into blood from the liver
• fuels stored in muscle, adipose tissue and liver
• the key is hormonal adjustment
• recovery time (produces ATP slowly)
• non suitable for intense exercise
• red muscle fibres (many capillaries, oxygen), common in thigh / leg, harder to increase size of fibres

Question 2

describe the lactic energy / glycolytic system (anaerobic)

Answer 2

• do not rely on oxygen
• the by product is lactic acid
• an accumulation of H+ causes muscular fatigue
• energy lasts less than 2 min (fast contraction fast fatigue)
• 400m run, 100m swim
• recovery time ranges from 20 sec (distribution of energy) -3 min
• active recovery (lactic acid - liver - glucose - glycogen)
• white muscle fibres (less capillaries)

Question 3

describe the ATP-CP energy system (anaerobic)

Answer 3

• do not rely on oxygen
• short duration, quick movement
• high intensity in short period of time (sprinters)
• great intensity (fast twitch muscle fibres)
• creatine phosphate (donates P to ADP) and glycogen (glucose) from muscle
• white muscle fibres (less capillaries) - common in arms, chest and shoulders, easier to increase size of fibres

Question 4

how does the body respond / adapt to exercise

Answer 4

• muscular (contraction) and skeletal (movement)
• cardiovascular (increase HR, BP, HB)
• respiratory (increase in gas exchange)
• nervous (control muscular fibres)
• chemical (hormones - adrenaline)
• all respond differently

Question 5

how does the muscular system respond / adapt

Answer 5

• muscle fibres are elastic and can change
• energy storage: increase in glycogen storage)
• hypertrophy: increase in volume of muscle fibres - especially white)
• fibre type: red vs white = genetic, ability to switch)
• motor control: connection between neuronal fibres and muscular fibres)

Question 6

how does the skeletal system respond / adapt

Answer 6

• less immediate than muscular response
• bone density = months, minimise the effects of bone related disorders
• constant low intensity exercise = increase density of bones (decrease arthritis)
• bony prominences as a result of exercise
• haglund’s deformity: enlargement of heel, runners, wearing tight shoes (change shape of bone)

Question 7

how does the respiratory system respond / adapt

Answer 7

• increase ventilation, accessory respiratory muscles (15% cardiac output = respiratory muscles)
• reduction of work required to breath, adrenaline (broncho dilation), fatigue resistant motor units, coordinated skeletal muscle (less energy consumed)
• 3 neural factors = increased ventilation
• psychological stimuli: anticipation
• simultaneous cortical motor activation: skeletal muscles / respiratory centres
• excitatory impulse: proprioceptors in moving muscle
• rest = 5L air / min (1/3 capillaries functioning, 2/3 dead space)
• exercise = >15L air / min, no dead space (3/3 functioning), maximum gas exchange

Question 8

how does the cardiovascular system respond / adapt

Answer 8

• HR, cardiac output (CO), BP = increase
• CO: amount of blood pumped every minute, increase stroke volume (blood pumped each HB) / heart rate (bpm)
• steady-state HR: rises linearly with work rate over range from rest to VO2max (ml/kg/min)
• dynamic: running cycling, slight increase SBP, DBP scarcely alters
• isometric: weightlifting, huge increase SBP and DBP
• difference: compression of intramuscular arteries presents vasodilation / increased BF = low O2 = high lactic acid = stimulation of chemoreceptors = excite SNS
• heart: adrenaline / endothelial secretion of nitric oxide / prostacyclin (vasodilators) = increase CO, coronary flow, endothelial cell shear stress, endothelial dependent vasodilation and SNS

Question 9

how does the left ventricle adapt

Answer 9

• endurance: cardio, increase internal volume of ventricle, wall thickness is constant, less BPM, increase SV
• strength: short, high intensity, increase in total volume but internal volume remains constant (increase thickness of wall - must beat against higher pressure)

Question 10

how does the nervous system respond / adapt

Answer 10

• nervous fibres connected with smooth muscle cells in walls of capillaries (can change amount of blood in specific organs depending on activity of our body)
• changes in blood flow to organs based on what requires energy during exercise
• no change in brain
• dramatic decrease in intestine
• dramatic increase in skeletal muscle and heart

Question 11

how does the coordination of skeletal muscle contraction occur

Answer 11

coordination:
- common movement = years of training
- walking / swimming = complex (coordination of entire body)
sympathetic influences:
- SA node: increase HR (less blood in venous, increase demand for arterial),
SV (increase contraction)
- dilates bronchi
- inhibition of urination and digestion (intestine movement)
- stimulates glucose release (adrenaline = liver release glycogen used by)
regulation of fluid volume:
- sweat = 1.8 L / hour, 10% of sweat = plasma volume (dense = embolism)
- fluid lost during exercise (sweat, respiration) = less urine
hormones:
- ADH, aldosterone and renin (reduce production of urine increase fluid retainment)