Quiz #1 answer Chapter 1 and 20 PDF

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Name: Quiz #1 1. Define work and power using the SI units, and calories Work (J) = Force (N) x Distance (m) Power (W) = Work (J) / Time (s) Calorie (Cal = kcal) = The heat energy needed to raise 1 ˚C of the temperature of 1 liter of water. 1 Cal is equal to 4184 joules or 4.184 kJ 2. When we calculate the work, body weight (a force) is commonly given in kilograms (kg), the unit for mass. However, sometimes kilopond (kp) is also used as the force unit. Explain the difference between the two. Kg is a unit of mass, while kp is the force exerted by one kg of mass in the standard gravity. Thus, kp means the kg-force (kgf). 1 kgf = 1 kp = 9.81 Newton. 3. A person whose body weight is 65 kg steps up and down on a 30 cm bench for 15 min at a rate of 30 steps per min. Calculate the amount of work and power, and kilocalories (kcal) for this person. Please show the process of solving the question as well. 4186 joules = 1 kcal Force = 65 kg x 9.81 N / kg = 637.65 N Distance = 0.3 m / step x 30 steps / min x 15 min = 135 m Thus, work = 637.65 N x 135 m = 86,082.75 N/m = 86,082.75 J Power = 86,082.75 J / 900 s = 95.65 J/s = 95.65 W Kcal = 86,082.75 J x kcal / 4184 J = 20.57 kcal 4. Calculate work and power in the following scenario: A person has just finished his/her workout on a cycle ergometer (using 2 kg resistance; 6 m•rev-1; 60 rev•min–1) for 15 minutes. Please show the process of solving the question as well. (1kg = 9.81N) Force = 2 kg x 9.81 N / kg = 19.62 N Distance = 6 m / rev x 60 rev / min x 15 min = 5,400 m Work = 19.62 N x 5,400 m = 105,948 N/m = 105,948 J Power = 105,948 J / 900 s = 117.72 J/S or 117.72 W 5. Describe the difference between direct calorimetry and indirect calorimetry Direct calorimetry measures caloric expenditure via total body heart produced in the thermally sealed chamber whereas indirect calorimetry estimates calorie expenditure via measurement of O2 consumed. 6. We can also calculate the work (Joules) performed by our body by assessing calorie expenditure, which can be collected through the measurement of body heat or oxygen consumption of the body. In this regard, 1) explain how the body heat measurement (direct calorimetry) and oxygen consumption (indirect calorimetry: open circuit spirometry) can be used to measure kilocalories (kcal); 2) describe how you use the value of kcal to calculate the work. 1) Direct calorimetry: the heat energy used to raise 1 ˚C of 1 liter of water is equal to 1 kcal. Thus, the measurement of total body heat production can be used to calculate total calorie expenditure. In contrast, indirect calorimetry: 1 L of O2 consumed by our body is equivalent to approximately 5 kcal. Thus, measurement of total O2 consumption can be used to estimate total calorie expenditure. 2) Since 1 kcal is equivalent to 4,184 J, the multiplication of total kcal by 4,184 J (1 kcal x 4,184 J/ kcal) will allow us to convert kcal to J.

Name: 7. A female student wants to know her total calories that may be burned during the endurance exercise. Calculate her total kcal using the following information. Also, express the energy expenditure (kcal) to the work (Joules). Please show the process of solving the question as well. Body Weight: 50 kg VO2 = 30 ml/kg/min Duration: 1 hour Total O2 consumption = 30 ml/kg/min x 50 kg x 60 min = 90,000 ml x 1L / 1000 ml = 90 L Calorie expenditure (kcal) = 90 L x 5 kcal / 1 L = 450 kcal Work (J) = 450 kcal x 4,184 J / kcal = 1,882,800 J 8. A college male student learned in his exercise physiology class that if he runs at 70% VO2max on a treadmill, he would burn 14.28 kcal every minute. So, he decides to run at 70% VO2max which can be sustained by the combination of the speed of running and the % grade of the treadmill. If he wants to choose his favorite running speed (150 meter per minute), what % grade does he need to choose to maintain his exercise intensity (70% of maximal oxygen consumption)? Use the following information. Please show the process of solving the question as well). Age: 22 years old Weight: 68 kg Height: 180 cm VO2max: 60 ml/kg/min Desired treadmill speed: 150 meter per minute Desired VO2 or exercise intensity: 70% VO2max Use this formula: Desired VO2 = 3.5 + (0.2 x speed) + (0.9 x speed x % grade) Desired VO2 = 60 ml/kg/min x 0.7 = 42 ml/kg/min 42 = 3.5 + (0.2 x 150) + (0.9 x 150 x % grade) 42 = 33.5 + (135 x % grade) 42 - 33.5 = 135 x % grade 8.5 = 135 x % grade 8.5/135 = 135 x % grade / 135 % grade = 0.063 x 100 % grade = 6.3 9. VO2 (ml/kg/min) can be estimated based on the formula: VO2 (ml/kg/min) = 0.2 x speed (m/min) +3.5 for horizontal running. Using this formula, please calculate estimated VO2 and the total energy cost (kcal) of a person, given the following. Please show the process of solving the question as well. Body weight: 65 kg Running speed: 7 mile per hour Exercise duration: 40 min

Convert mile /h to meter (m) / h: 7 mile/h x 1,609.34 m/mile = 11,265.38 m/h Convert m/h to m/min: 11,265.4 m/h x h/60 min = 187.76 m/min VO2 = (0.2 x 187.76) + 3.5 VO2 = 41.05 ml/kg/min Total estimated VO2 (L) = 41.05 ml/kg/min x 65 kg x 40 min x 1L/1000 ml = 106.73 L Kcal = 106.73 x 5 kcal / 1 L = 533.65 kcal

Name: 10. VO2 (ml/kg/min) during running with an incline can be also estimated based on the formula: VO2 (ml/kg/min) = 0.2 x speed (m/min) +3.5 for horizontal running and 0.9 x speed (m/min) x % incline (expressed as decimal equivalents). Using the two formulas above, please calculate estimated VO2 and the totally energy cost (kcal) of a person, given the following. Please show the process of solving the question as well. Body weight: 80 kg Running speed: 180 m/min Incline (% grade): 5% Exercise duration: 30 min

VO2 (ml/kg/min) = (0.2 x 180 + 3.5) + (0.9 x 180 x 0.05) = 39.5 + 8.1 = 47.6 Estimated total VO2 (L) = (47.6 ml/kg/min x 80 kg x 30 min) x 1L / 1000 ml = 114.24 L Total energy expenditure (kcal) = 114.24 L x 5 kcal / 1 L = 571.2 kcal 11. List and explain in detail three factors that influence exercise efficiency 1) Exercise work rate: the efficiency reduces as work rate deviates from the optimal work rate. 2) Speed of movement: the deviation of the speed from optimum speed interferes in exercise efficiency 3) Muscle fiber types: fast muscle fibers require more energy (ATP) usage; thus, greater percentage of slow muscle fibers provide higher efficiency. 12. Calculate net efficiency given the following. Please show the process of solving the question as well. Resting VO2 per min = 0.25 L Exercise VO2 per min = 3 L Work rate = 200 Watts (=200 J/s) Hint) both the nominator and the denominator should be converted to kcal (e.g., O2 to kcal and work rate to kcal/min) VO2 used during exercise: 3 L – 0.25 L = 2.75 L Conversion of VO2 to kcal: 2.75 L x 5 kcal / 1L = 13.75 kcal Conversion of the work rate (W) to kcal: (200 J/s x 60 s) x 1 kcal / 4184 J = 2.87 kcal Net efficiency (%) = (Work output (rate) / Energy expended above rest) x 100 = (2.87 kcal / 13.75 kcal) x 100 = 20.86 % 13. Briefly explain the difference between absolute and relative VO2max. Absolute VO2max represents the maximum rate of oxygen uptake per min attained at the end stage of a maximal exercise capacity test (treadmill running or cycling), typically expressed in L/min. Relative VO2max depends on body weight. This value presents the maximum rate of oxygen uptake per kg of body weight per min. Thus, relative VO2max is calculated by dividing the absolute VO2max by body weight (kg), typically expressed as ml/kg/min. When comparing the maximum capacity of oxygen consumption among individuals, relative VO2max should be used because the absolute VO2max increases in proportion to body weight.

Name: 14. Explain why relative VO2 max might be the single most important factor in predicting distance-running success in a heterogeneous group of runners? The answer is subject to students’ opinion. 15. Define validity and reliability and explain why these two factors are critical in order to acquire trustable physical performance data The answer is subject to students’ opinion. 16. List and explain four criteria used to determine the certainty of VO2 max? 1) Reaching a plateau in VO2 with increasing work rate due to hyperventilation 2) Rising of blood lactate concentration above 8 mM (8 mmol/L) 3) Increase in respiratory exchange ratio (VCO2/VO2) equal or above 1.15 4) Reaching a heart rate 10 above or below of the maximal heart rate (220-age) 17. Define exercise economy and explain how it is evaluated? The amount (quantity) of oxygen required at a given speed of running or work rate. Lower amount of oxygen consumption at a given work rate is an example of better exercise economy. Exercise economy is assessed by plotting the oxygen consumption as a function of speed or work rate. 18. Describe how long-distance running time can be estimated on the basis of the running speed and the lactate threshold? 1) Plot both VO2 and lactate concentration as a function of the speed of running while measuring VO2max 2) Determine lactate threshold (an exercise intensity or running speed at which the blood concentration of lactate begins to increase exponentially or non-linearly). 3) Find VO2 corresponding to the lactate threshold 4) Find the speed corresponding to the VO2 at which the lactate threshold occurs 5) Divide the total distance of running by the running speed at lactate threshold This procedure will allow coaches or performance evaluators to estimate potential maximal running time. For instance, if a person’s running speed at the lactate threshold is 300 m/min and is supposed to run 10,000 m with the same speed, the estimated running time is 33.33 min (i.g., 10,000 m / 300 m/min). 19. List types of test utilized to determine ultra-short-term maximal anaerobic power and short-term anaerobic glycolytic power and briefly explain the processes of the tests. The answer is subject to students’ opinion. 20. Calculate VO2 requirement of cycling, given the following information. Please show the process of solving the question as well. VO2 (ml/kg/min) = [(1.8 x work rate) / body weight] + 7 Body weight 65 kg Resistance: 2 kg Distance: 6 meters per revolution Speed: 70 revolutions/min (Work rate in kgm/min) Work rate = 2 kg x (6 m / rev x 70 rev / min) = 2 kg x 420 m/min = 840 kgm/min VO2 (ml/kg/min) = [(1.8 x 840) / 65 kg] +7 = (1512 / 65) + 7 = 23.26 + 7 = 30.26

Name: 21. Explain why the ventilatory threshold can be used to estimate the lactate threshold and rationalize how the lactate threshold can be used to estimate maximal steady-state running speed. The answer is subject to students’ opinion.

22. Discuss limitations of physiological testing conducted in the laboratory, compared to field tests. The answer is subject to students’ opinion.

23. What are the potential factors that affect VO2max? 1) Genetic variations affecting muscle fiber types and quality of mitochondria 2) Types (modes) of training 3) Duration and intensity of training...