Heart rate response Saratha Kugendran

Questions you might have: How does the heart rate respond to exercise? Does it respond differently to maximal and submaximal exercise? How does the heart rate differ between the rest, exercise and recovery phases of movement?

REST PHASE Anticipatory rise BEFORE EXERCISE due to ADRENALIN which is released by the sympathetic nervous system. This leads to a decrease in activity of the PARASYMPATHETIC nervous system.

EXERCISE PHASE During exercise, the heart rate increases rapidly. Proprioceptors detect MOVEMENT. Production of CO₂ increases blood acidity which is detected by CHEMORECEPTORS in the aorta. There are increased SYMPATHETIC nerve stimulations which in turn stimulate the SAN.

RECOVERY PHASE The heart rate is INCREASED and this stimulates BARORECEPTORS. There are increased parasympathetic nerve impulses and therefore decreased SYMPATHETIC stimulation The heart rate is maintained then DROPS rapidly.

Maximal exercise What do the letters represent? Discuss with your partner. A= ANTICIPATORY RISE B= SHARP RISE C= HR CONTINUES TO RISE E= RAPID DECLINE F= SLOWER RECOVERY RATE On your sheets, write a brief description of each letter.

Now try Submaximal exercise on your own A= ANTICIPATORY RISE B= SHARP RISE D= STEADY STATE E= RAPID DECLINE F= SLOWER RECOVERY

Discuss with your partner why the graphs look so different? Use the words that letters A-F represent, to help you with your answer. 5 MINUTES

Jun Qu 4: Performance may develop as a result of exercise and learning. (a)(i) Explain what happens to your heart rate prior to exercise (2 marks) (ii) Exercise causes the heart rate to change. Explain what causes these changes. (4 marks) (i) 1 Heart rate increases in anticipation of exercise; 2 Caused by release of adrenaline. (ii) 1 During exercise – increasing release of carbon dioxide through aerobic energy supply; 2 Leads to increasing acidity (levels of CO2) in blood; 3 Detected by chemoreceptors; 4 In aorta/carotid artery/medulla; 5 Nerve impulses to (cardiac centre in) medulla; 6 Decreased parasympathetic stimulation; 7 Increased sympathetic stimulation; 8 Of SAN to increase HR.

(i) Heart rate increases/anticipatory rise; (Prior to exercise) adrenaline/noradrenaline released (by the sympathetic nervous system); Parasympathetic (Vagus) system decrease in activity/impulses; (ii) Heart rate rapidly/equiv increases (During exercise) proprioceptors/mechanoreceptors/sense organs detect movement; Production of carbon dioxide/increased blood acidity/lactic acid/pH falls; Stimulates chemoreceptors (in aorta/carotid body/carotid artery); Stimulates cardiac accelerator/medulla (in brain); (Increased) sympathetic stimulations/release of noradrenaline/norepinephrine; Sino Arterial Node (SAN) stimulated/excited; (iii) Increased heart rate raises blood pressure; Stimulates baroreceptors (in aorta/carotid body/carotid artery); (Increases) Parasympathetic/ Vagus system; Decreases Sympathetic stimulation; Release of Acetylcholine; Heart rate is high/maintained and then drops/decreases. (c) A 17-year-old runs 400 metres with maximum effort in 60 seconds. Describe the variations in heart rate and how these changes are achieved during the: (i)rest period immediately prior to the start of the 400 metres.(3 marks) (ii)The 400 metre race (exercise period)(4 marks) (iii)five-minute recovery period after the 400 metres.(3 marks)

Have these questions been answered? How does the heart rate respond to exercise? Does it respond differently to maximal and submaximal exercise? How does the heart rate differ between the rest, exercise and recovery phases of movement?