In the MSU vs Penn State football game the Penn State wide receiver was chased d
ID: 74270 • Letter: I
Question
In the MSU vs Penn State football game the Penn State wide receiver was chased down by an MSU defender. The MSU defender was able to accelerate faster than the Penn State player and knock the ball out of his hand. The MSU player then picked up the ball, changed directions and made a 10 yard return before being tackled. Using your knowledge of exercise physiology explain the fitness differences between the two players, comment on VO2, skeletal muscle force production, metabolism and cardiac output.
Explanation / Answer
Based on the given data,
1)
MSU defender has more fitness, than the Penn State wide receiver. This is because the MSU defender chased down, accelerates faster and knocks the ball out of Penn State wide receiver and again took 10 yard return. So, the MSU defender has more aerobic fitness, flexibility, muscular strength and Bone strength, than Penn State wide receiver.
2)
The VO2 is nothing but maximal aerobic capacity or fitness or maximal oxygen consumption. The formula for calculation of VO2 Max is:
VO2 = 15.3× maximum heart rate/ resting heart rate
MHR = 208-(0.7×age)
The common value of VO2 for endurance athletes is about 75 ml Kg-1 min-1 (note for mean body mass 66 kg). Therefore, a person who has more maximal oxygen consumption can run faster.
Thus, the MSU defender has more VO2 then Penn State wide receiver.
3)
The skeletal muscle force production:
The total muscle force is generated by the passive and active muscles forces. The passive forces are generated by the stretching of cross-bridges of muscle, whereas active forces are generated by hydrolysis of ATP, which results molecular conformation. The person who consumes more oxygen (O2) will produce more ATP for active force generation and thereby passive force generation.
Thus, the MSU defender has more skeletal muscle force production then Penn State wide receiver.
4)
Metabolism is a combined sate of two mechanisms called anabolism and catabolism. The ATP (energy) is produced in catabolism. So, both players have active catabolism, but person who have more erythropoietin (EPO) levels consume more oxygen, and thereby degrade more glycogen and produce more ATP.
Erythropoietin is a hormone, which is released by the kidneys. It stimulates the production of red blood cells in the bone marrow. Low blood volume or oxygen levels (hypoxic conditions) stimulate the kidneys to release erythropoietin. Through a negative feedback mechanism, the kidneys sense reduced oxygen, and they produce the hormone erythropoietin. Even their muscles enter into anaerobic catabolic state, the increased EPO regulate hypoxic conditions.
5)
Cardiac output is the volume of blood which is pumped by heart by left or right ventricle in one minute of time interval. Cardiac output depends on the heart rate, heart contraction per minute and stroke volume. Variations in stroke volume or in the heart rate change the cardiac output. The Cardiac output is usually expressed in liters per minute (L/min).
Cardiac volume = heart rate (HR)× stroke volume (SV) = heartbeats per minute volume of left ventricle blood ejected per beat.
The factor that effect cardiac output is:
Heart rate (HR) defined as the speed of the heart which is calculated by heartbeat takes place per minute. The exercise stimulates Sympathetic nervous system (SNS), and initiation of Fight or Flight stimulus. It results the production of epinephrine and Nor-epinephrine. Therefore, the Herat rate rises and increases the contractility.
Stroke volume (SV) is the blood volume which is pumped from one heart ventricle with each heartbeat. The exercise, like running, cycling are positive agents, which affect the end diastolic volume (EDV) of stroke volume. During exercise, the stroke volume reaches its peak when the cardiac output is at about 50 percent of its maximum. Therefore, variations in stroke volume or in the heart rate change the cardiac output.
In athletes, the cardiac output increases due to the regular exercise (stroke volume increases).