What is the effect of walking, skipping, and running on a person’s heart rate? Hypothesis:
If the intensity of the action increases (walking<skipping<running), then the heart rate will also increase because the faster the legs are moving, the faster the leg muscles need to contract. When the leg muscles contract faster, more energy is used, and the heart will pump faster to deliver oxygen through the blood stream to muscles, organs, and organ systems that need it in order for cellular respiration to occur. Variables:
The independent variables for this experiment are the 3 actions that will be carried out by test subjects: walking, skipping, and running. The dependent variable is the heart rate of each test subject (measured by number of beats per minute). The controlled variables include the temperature of the hallway where the experiment is being conducted, which is at room temperature; the amount of time each action is to be completed (1 minute), timed with a stopwatch; the amount of time each subject’s heart rate is measured for (15 seconds), timed with a stopwatch; the amount of time allotted for the subject to rest in between each action (1 minute), timed with a stopwatch; using the same method of measuring heart rate (having test subjects count the number of beats they can detect with their fingers); having the test subjects remove backpacks and heavy sweaters that can cause extra exertion; having the test subjects perform each action on the same terrain (the 2nd floor hallway); and completing all testing on the same day.
The hypothesis stated that the heart rate of the test subjects would increase most after running, which was proven true after the experiment. When test subjects walked, skipped, and ran for 1 minute for each action, with a 1 minute break in between each action, the heart rates of the test subjects increased most after running, as shown in figure 1. As the speed the subjects’ legs had to move increased, the speed of leg muscle contractions increased. With each contraction, more energy is being used. Energy is produced through cellular respiration, which uses oxygen diffused from the bloodstream. The heart must pump blood faster to deliver oxygen diffused blood to the areas that need it, mostly the leg muscles. Therefore, the heart rate of the test subjects increased as the intensity and speed of their actions did. The average BPM while resting was 102, and it increased to 113 after walking. It increased further after skipping, going from 113 BPM to 152. And the action that required the most speed had a BPM of 207. Cellular respiration: 6O2 + C6H12O6 → 6CO2 + 6H2O + energy Experimental Error:
One error in this lab was the way the heart beats were counted. The fact that each test subject measured their own heartbeat using their fingers leads to inaccurate measurement because the test subjects’ heart rates could be racing and the test subjects could have missed a beat or two, which could make a significant difference when calculating the BPM, because when calculating the BPM, the number of beats per 15 seconds needs to be multiplied by 4. If even 1 beat is miscounted, that’s an extra 3 beats added on to the BPM. Also, there were some occasions where the test subjects couldn’t find their pulse immediately after the action, which once again can cause miscalculation of the BPM. In addition, the lab didn’t specify where to take the pulse from, so one test subject may have taken it from the neck, while another from the wrist, which could lead to warped results.
Plus, the 1 minute time allotted between the actions was not long enough for the heart rate of the test subjects to return to its original state. Lastly, the subjects were not identical and therefore had anatomical differences, such as having a larger neck/wrist, having larger blood vessels, or the proximity of the vein to the surface of the neck/wrist. Using a heart monitor would have gotten more accurate results. Another error in this lab was the variety of test subjects. Each subject had different articles of clothing which could have affected how each subject performed each action (ie. different fabrics can store heat better than others can, type of shoe can affect how the subject runs, subjects wearing tighter pants will have more restriction than those who aren’t, etc.). Also, many other aspects of the subjects could affect how they performed: their physical fitness could determine how hard their body needs to work, taller subjects might have to work harder because their heart needs to pump blood further, what they ate beforehand, how much sleep they got, the subject’s competitive mentality, weight, gender, age, and build.
If this experiment was to be repeated, the subjects chosen to participate should, ideally, be of the same gender, weight, height, build, etc. Also, the subjects should have a ‘uniform’ of sorts to wear (ie. gym clothes). The final major error in this lab was the location the experiment was performed in. It was carried out in the 2nd floor hallway, after school. But the hallway has 4 corners, which requires the test subjects to slow their pace slightly to turn the corner, which could slow the heart rate, even slightly. Plus, sport teams were warming up in the same hallway at the same time, so test subjects may have had to slow down to avoid collision. In addition, the actions performed may have caused the test subjects to feel subconscious or embarrassed, causing the heart rate to increase. The experiment should have been carried out on a flat, straight terrain, with no interruptions or anything to distract the test subjects.