Research Question

Research Question In what ways do five standard cardiovascular activities of increasing intensity (walking, speed-walking, jogging, running and sprinting), over one-hundred metres, affect the measured heart rate of a fourteen-year-old male, if the subject is given adequate time to return to their resting rate? Introduction and Background Information Figure SEQ Figure \* ARABIC 1- Infographic diagram outlining points mentioned in ‘background information’ (Toro, 2017). Understanding the circulatory system is of the utmost importance and relevance to this investigation. The circulatory system within the human body is one of the most complex yet vital processes for the continuation of life. Essentially, the circulatory system is composed of three separate systems that conjoin to transport a mean of 5.1 litres of blood, filled with nutrients, carbon dioxide, oxygen and hormones to and from cells. These systems are as follows: cardiovascular (primarily involving the heart), pulmonary (primarily involving the lungs), and systematic circulation (composed of veins, arteries, as well as the coronary and portal vessels in the body) (Toro, 2017). These will be elaborated upon for best understanding of the context of this investigation. The organ that that acts as a pump to force oxygenated and de-oxygenated blood throughout the body is called the heart and it is located just behind and to the left of the breastbone. In accordance to rest, the heart will contract at a slower rate, as there is less demand for oxygen to be channelled through the body, whereas it can rapidly increase to almost 220 beats (or contractions) per minute to comply with oxygen demands from intense muscle extensions and contractions. These contractions can simply be measured by placing the middle and index fingers of an individual to their necks underneath either side of their lower-jaws, and counting how many times blood is felt creating a small vibration to the fingers per minute. It pumps blood across the entire body though channels known as blood vessels, of which there are five main types: arteries, arterioles, capillaries, veins and venules. Arteries carry highly oxygenated, high pressure blood. Arterioles are much narrower blood vessels that branch off arteries and transport less pressurised and lower volumes of blood to capillaries. Capillaries are the most common yet smallest blood vessels in the body, and can be found running through out close to all tissues in the body. They carry blood closely to cells of tissues to exchange nutrients, oxygen and waste products such as carbon dioxide. Veins are large vessels that transport low-pressure, de-oxygenated blood back to the heart for it to be re-oxygenated within alveoli (air sacs connected to the lungs). Venules simply take blood from many capillaries and return the collected blood in to veins, and are the counterparts of arterioles ("Cardiovascular System", 2017). Erythrocytes (also known as red blood cells) make up 45% of blood volume, and are produced inside of red bone marrow. Their purpose is to move oxygen in the blood through a red pigment known as haemoglobin. Haemoglobin contains proteins and irons joint together to maximise the cells’ oxygen capacity ("Cardiovascular System", 2017). Figure SEQ Figure \* ARABIC 2- Entirety of the circulatory system in simplest form ("Circulatory System", 2017) Additional to understanding the circulatory system, knowledge of cellular respiration is also pertinent to this investigation. Cellular respiration can be defined as the breakdown of glucose and other respiratory substrates to create energy-carrying molecules known as ATP (adenosine triphosphate). These molecules are created by a process called glycolysis. Glycolysis is a biochemical process that metabolises glucose and is anaerobic (meaning that it does not require oxygen). ATP is therefore produced and used in cells due to its fast releasing energy properties (“Glycolysis”, 2017). These molecules can be recycled so that a constant stream of energy-rich ATP is accessible for all metabolic pathways (linked chemical reactions occurring inside a cell). The majority of cell processes require ATP for a reaction to receive its obligatory energy ("BBC Bitesize - Cellular respiration", 2017). Especially within this investigation, it is important to note that muscle contractions require both oxygenated blood and ATP to be sustained. Hypothesis By careful analysis of background information related to the investigation, it can be hypothesised that the test subject’s heart rate will maintain a consistent number of beats per minute, per independent variable (type of exercise), considering that the subject is given time to rest until their heart rate slows and returns to its resting rate. However, the heart rate will probably functionally increase in relation to the intensity of each type of exercise performed. Methodology Variables Type of Variable Investigation Variables Method of Control Independent Type of exercise, with a total of five: Walking, Speed Walking, Jogging, Running, Running Requiring the subject to do each a total of three times before moving to the next exercise. Dependant Test subject’s heart rate after completing an integer of a test. Making sure the subject exercises at a rate consistent to the activity at hand. Controlled Subject’s resting heart rate, distance each exercised had to be performed across. Requiring the subject to rest completely for four minutes until their heart rate had been measured and successfully returned to their resting pace. Requiring the subject to complete each test up and down a fifty-metre distance (total of one-hundred metres). Materials Trundle Wheel to measure one-hundred metre distance. A fourteen-year-old male participant willing to perform fifteen exercises across one-hundred metres with increasing intensity. Clock, watch or phone with a stopwatch function. Closed footwear for participant. Writing equipment such as a pencil and paper to record data, or a digitalised device with similar functionality. A minimum of one other person to record heart beat readings via the aforementioned writing/typing equipment. A water bottle full of water on standby at the request of the subject. Safety and Ethical Considerations The test subject willingly gave verbal consent to be subjected to varying levels of cardiovascular exercise intensity. The test subject wore closed shoes to prevent stepping on anything sharp or dangerous. All physical activities were undertaken outside with teacher supervision. No plant life, shrubbery or animals were harmed or destroyed during this investigation. Hydration was provided to the test subject to remain in a healthy state. The subject was given adequate time to return to a resting heart rate. The test subject was not exposed to any activities irrelevant to the investigation. Figure SEQ Figure \* ARABIC 3 - Satellite image of area that all tests were conducted. The pink lines represent the 50 metre distance forward and back to formulate a 100 metre distance in total (Google Maps, 2017). Procedure The investigation begun by finding an appropriate area for the subject to perform all fifteen tests. In the case of this investigation, the school courtyard was deemed suitable. Then, with the use of a trundle wheel, a fifty metre distance was paced out, using the click of each rotation to be one metre, therefore, the subject would need to run up and down this distance to meet the one hundred metre requirement of the research question. The subject proceeding to the designated starting point, before being required to stand in as still and tranquil state as possible for five minutes. During this time, a filled water bottle was placed on the ground to be given to the subject upon their request to maintain hydrated. They then proceeded by placing their index and middle fingers underneath their lower-jaw to count their pulse rate for one minute, which was timed by another team member using a stopwatch. This heart rate was considered as the resting heart rate, and was used as a controlled variable. Next, the subject was asked to walk at their standard walking pace in a straight line to the disclosed point of which the trundle wheel clicked to represent fifty metres, and perform a U-turn and come back to the starting point, maintaining a linear path. The moment the subject had successfully walked the one-hundred metre distance, they took their pulse rate using the same two fingers and position as before for one minute, keeping upright. This data value was recorded. The subject then sat down and was given four minutes to regain their breath and energy, until they measured their pulse rate to one minute to check if it had returned to the original resting heart rate. An increase or decrease of two beats per minute was considered an acceptable margin of error. In no case did the subject not return to their resting heart rate by four minutes, however, if the heart rate were to be more than two beats per minute above resting, the team would have been prepared to allocate an additional four minutes of rest to the subject for full recovery. This precise process was repeated two more times involving the subject to walk one hundred metres to create a total of three data values of the subject walking. The process was continued with four more exercise of increasingly strenuous intensities (in chronological order): speed-walking, jogging (approximately 60 percent capacity), running (approximately 80% capacity), and sprinting (full capacity). All fifteen tests took approximately ninety minutes in total. Quantitative Data Raw data Independent variable Walking Speed Walking Jogging Running Sprinting Test 1 (beats/min): 85 +/- 1 106 +/- 1 113 +/- 1 119 +/- 1 130 +/- 1 Test 2 (beats/min): 85 +/- 1 110 +/- 1 110 +/- 1 115 +/- 1 133 +/- 1 Test 3 (beats/min): 87 +/- 1 100 +/- 1 96 +/- 1 122 +/- 1 124 +/- 1 *The test subject’s resting heart rate was 79 beats/minute. sample calculations To construct clear, relevant processed data to be graphed, calculations must be performed for population standard deviation, sample mean and percentage increase from resting heart rate. All calculations for population standard deviation and sample mean were undergone through Microsoft Excel number processing, however percentage increase was done with use of a scientific calculator. In the case of this investigation, sample mean and standard deviation have both been used due to their importance when evaluating the validity and quality and fairness of the processed and graphed data. Excel uses the following formulae to find the respective values: Percentage increase from resting heart rate: Increase in beats/minute = Individual data value – resting heart rate (79 beats per minute) Percentage increase = (Increase/79) * 100 (Skillsyouneed.com, 2017) Sample Mean: µ = Σ x / n µ represents the sample mean. Σ represents the sum of all the number of observations per exercise. n represents the number of tests taken for the study. x represents the given values per exercise. (Kaushik, 2011) Walking Sample Mean µ = Σ x / n µ = (85+85+87)/3 µ = 85.67 beats/minute Speed Walking Sample Mean µ = Σ x / n µ = (106+110+100)/3 µ = 105.33 beats/minute Jogging Sample Mean µ = Σ x / n µ = (113+110+96)/3 µ = 106.33 beats/minute Running Sample Mean µ = Σ x / n µ = (119+115+122)/3 µ = 118.67 beats/minute Sprinting Sample Mean µ = Σ x / n µ = (130+133+124)/3 µ = 129 beats/minute Figure SEQ Figure \* ARABIC 4 - (Mathsisfun.com, 2017) Standard deviation (population): σ represents population standard deviation. µ represents the sample mean. Σ represents the sum of all x values taken from the mean squared. N represents the number of tests taken for the study. xi represents the individual values per exercise. (Mathisfun.com, 2017) Walking Population Standard Deviation 0.94 Speed Walking Population Standard Deviation 4.11 Jogging Population Standard Deviation 7.41 Running Population Standard Deviation 2.87 Sprinting Population Standard Deviation 3.74 Processed Data Independent variable Walking Speed Walking Jogging Running Sprinting Sample Mean (beats/min) 85.67 105.33 106.33 118.67 129 Standard Deviation (P) 0.94 4.11 7.41 2.87 3.74 % Increase Test 1 7.6 34.18 43.04 50.63 64.57 % Increase Test 2 7.6 39.24 39.24 45.57 68.35 % Increase Test 3 10.13 26.58 21.52 54.43 56.96 Graph SEQ Graph \* ARABIC 1 - Graph showing the percentage increase from the resting heart rate of the test subject per exercise, along with error bars representing population standard deviation for each exercise. Qualitative Data Subject slipped and almost fell over during the second test of running. A school staff member was in the way of subject whilst completing the third test of walking, therefore subject had to maneuver around them. The subject had just finished presenting an English class oral presentation in the previous period, and was noticeably relaxed before and during all test partaken when speed walking. Subject was recorded panting considerably more during and after all tests taken place both running and sprinting. Timer to record the one-minute-worth of heart rate measurement was delayed by approximately ten seconds immediately after the third test of jogging took place. The sun arose from outside the clouds during the first and second tests of sprinting, making the temperature noticeable hotter. Subject reported knee to be in considerable pain during all tests spent jogging. Subject completed all tests of all exercises wearing formal uniform excluding a blazer, but consistently wore the school jumper. Subject reported that as the towards the end of each minute spent measuring heart rate, its contraction rate began to slow down towards the end. statement of data and measurement uncertanties Given that the both the raw data and processed data are discrete, a trendline (both linear and exponential) with an ‘r-squared’ value would be irrelevant and invalid to use as evidence within the discussion. The population standard deviations for four out of the five exercises were to be expected, however with the third test of jogging resulting in a definite outlier value, the standard deviation has a greater spread, and is therefore less reliable than the other data entries. The defined increase of heart rate from its resting value is to be expected as the exercises became more physically demanding on the individual. The consistent occurrence of decreased increase of heart rate on the third test for every exercise has been noted and will be discussed further during the discussion. The measurement uncertainty included in this investigation involves: +/- 0.5 cm on the trundle wheel when measuring distance, +/- 1 beat per minute when counting pulse rate, +/- 0.1 seconds on the stopwatch. These can all be considered systematic errors. Uncertainty can also be found in the qualitative data, such as the subject’s knee being in pain, the sun causing a temperature increase, the subject performing all tests whilst wearing a jumper with formal uniform, a teacher being in the way of the subject’s linear path, the subject finishing an English assessment earlier in the day, and almost falling over whilst running. These occurrences can be attributed to random error in the experiment. Discussion All the quantitative and quantitative data collected and organised in this investigation will help to answer the research question. Initially however, the data requires some explanation and interpretation. To begin with, it is clear to see the defined relationship between the intensity of the cardiovascular exercise and the percentage increase, with the highest increase from the resting heart rate of the subject was 68.35% (or 133 beats per minute +/- 1) after the second test during sprinting. Although, this may have additionally been caused by the subject’s body undergoing thermoregulation (a trait unique to mammals that gives bodies the ability to maintain consistent core temperatures) by sweating whilst the sun was out, in a jumper and long pants ("Cardiovascular System Science: Investigate Heart-Rate Recovery Time", 2017). Another definitive point can be noted from the graphed data, and that is the consistent decrease in resulting heart rates from all the third tests. Studies from the ‘Scientific American’ magazine have shown that individuals who partake in over eighty minutes of medium intensity cardio per week (often long-distance cycling or cross country) have stronger cardiovascular systems than average. Because of their increased stamina, they are often able recover and adjust their heart and (consequentially) breathing rates much faster than those who don’t. In the case of this investigation’s subject, they actively train for competitive cross country each week, which confirms this research. This means that the subject’s cardiovascular system most likely took the first two tests in all forms of exercise to adapt to the task, and had to work slightly less to complete their third tests. Next, it is important to address the outlier of the data. the third test performed when jogging. It was 15.2 beats per minute lower than the combined sample mean of the other two data points when jogging (which equated to 111.5 bpm), consequentially resulting in a very high population standard deviation for all three jogging values, widening their spread, and thus reducing the credibility and validity of the data. This can be accredited to the systematic error of the team member who displayed a delayed reaction of ten seconds during that test, and this subsequently corroborates with another piece of qualitative data: the subject reporting their heart rate slowing down towards the end of each one-minute measurement regarding heart rate. During the ten seconds that were lost after this test was completed, the subject’s heart rate would have been given additional time to stabilize. This occurrence is also mentioned within the same ‘Scientific American’ study. The measurement uncertainties (systematic errors) involved with the trundle wheel, stopwatch and heart rate counting were extremely small in the case of this experiment and would have had miniscule impacts on the outcomes of the dependent variables (data). However, the random errors recorded in the qualitative data were most likely the largest contributing factors to the high standard deviations of this investigation, and ramifications to the methodology will be discussed within the evaluation. Evaluation strengths and weaknesses Strengths of the Investigation Weaknesses of the Investigation Relevant controlled variables were used with appropriate guidelines to keep the test fair and valid (resting heart rate, distance activities were performed, time counting heart rate). Due to an outlier in the test spent jogging, the increased standard deviation has rendered the all jogging data much less reliable. The consideration of environmental, safety and ethical implications of the experiment ensured a minimal impact to the surrounding environment in the court yard, and the utmost safety of the test subject. Subject wasted more energy (through thermoregulation) by being in constrictive and warm formal uniform, which therefore increased their heart rate. across recorded data values. This lessened the credibility and validity of the investigation. The occurrence of a considerable amount of additional systematic and random further reduced the credibility and validity of the investigation. Counting pulse rate by hand may have led to a wider spread of data. recommendations to improve methodology and extension In the instance of an extended period to reperform the investigation being granted, several altercations would need to take place ensure minimal systematic and random error, allowing for more accurate and valid results. The first of which would be to bring a change of active-wear clothes and track shoes for the subject to provide more freedom of movement and better grip on the grass. Second, the investigation member in charge of timing heart rate should consistently be paying attention to reduce the chance of an outlier occurring such as the one that took place when jogging, creating a wider spread set of data. Thirdly, the experiment should take place under shade, to reduce stress on the subject’s thermoregulatory system. Lastly, a device such as a finger-tip heart rate monitor would be used to increase the accuracy of the data, eliminating human systematic error when counting, and the measurement uncertainty of using a stopwatch. Potential ways to extend the investigation would include having the subject perform more and different categories of cardiovascular-intensive activities, such as varying intensities of swimming, cycling, and weight lifting. This would further increase the amount of data to analyse, and look for trends in the different types of exercises. Additionally, these extensions of the investigation could be performed with people of both genders and of different ages, to view the relations in data between genders and ages. Conclusion In summary, this investigation confirmed the original hypothesis to the research question. Each independent variable of increasing cardiovascular intensity (although not functionally), had a clear influence on the subject’s heart rate. The higher the intensity of exercise, the greater the subject’s heart rate was immediately after the exercise. The biggest short-coming of this investigation was the numerous random errors recorded in the qualitative data. Perhaps if the solutions suggested in the evaluation were implemented into a future investigation with the same research question to this, a clearer, mathematical relationship could be drawn between a subject’s heart rate and the intensity of the cardiovascular-intensive exercise they performed. References BBC Bitesize - Cellular respiration. (2017). Bbc.co.uk. Retrieved 2 June 2017, from http://www.bbc.co.uk/education/guides/z2vbb9q/revision Cardiovascular System. (2017). InnerBody. Retrieved 2 June 2017, from http://www.innerbody.com/anatomy/cardiovascular-male#full-description Cardiovascular System. (2017). WebMD. Retrieved 2 June 2017, from http://www.webmd.com/heart/cardiovascular-system Cardiovascular System Science: Investigate Heart-Rate Recovery Time. (2017). Scientific American. Retrieved 2 June 2017, from https://www.scientificamerican.com/article/cardiovascular-system-science-investigate-heart-rate-recovery-time1/ Circulatory System. (2017). Teachpe.com. 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