Pulse rate practical

Individual - Discussion answers The graph is a line graph, with time/s on the x-axis and heart rate/beats per minute (bpm) on the y-axis. a) What was the lowest heart rate recorded before the exercise period? Provided results, 61 bpm b)What was the highest heart rate recorded during the exercise period? Provided results, 137 bpm c) What was the percentage increase of the highest reading taken during the exercise period compared with the lowest taken during the resting period? Provided results, 129.59% (from 137  61/61  100) 4. What else, apart from increased heart rate, affects the cardiac output (the volume of blood discharged from a ventricle, per minute)? Stroke volume (NB: cardiac output = heart rate  stroke volume  CO = HR  SV) 5. What was the purpose of the increased heart rate (and cardiac output) during the exercise period in relation to just the respiratory gases and the skeletal muscles? For a faster rate of delivery of oxygen to the exercising muscles and a faster rate of removal of CO2 from them. More oxygen is needed as the rate of aerobic respiration is increased during exercise to provide more ATP for more muscle contraction. And there’s a faster rate of CO2 production from aerobic respiration. (Lactate and heat aren’t relevant in this answer.)

Group – discussion answers 1 Draw histogram – show and tell Draw a scatter diagram of post-exercise heart rate against resting heart rate for the participants. Is there a correlation? X axis = mean resting heart rate b.p.m. Y axis = heart rate after exercise b.p.m. Yes, a positive correlation, as resting heart rate of subjects increased so did the immediate post-exercise heart rate, i.e. people with higher resting heart rates tended to have higher post-exercise heart rate. 3 (a) mean and (b) standard deviation – class results

Group – discussion answers 4 a) How much higher as a percentage is 63 than 60? 5% (from 63  60; ÷ 60 × 100) 4 b) Suggest why the heart rates (in beats per minute) determined over 15 seconds lacked accuracy. They lacked accuracy as accuracy is closeness to an accepted value (here, arguably the 63 beats per minute) and the heart beat rate taken from the 15 seconds results were 5% off that. 5 The immediate post-exercise heart rate can be taken as roughly ‘a measure of the heart rate at the end of the exercise period’. Why is it better to measure it over 15 seconds from 5 to 20 seconds after stopping the exercise, rather than over one complete minute? Because the heart rate is quickly reducing and here, the result taken for the 15 seconds close to the end of the exercise is likely to be more accurate than the result taken over one complete minute.