School for Professional Studies
Saint Louis University
Part I—The Adventure Begins … and Comes to a Screaming Halt
1. What body systems are primarily affected and what physiological changes would you expect Joe and Frank to experience during such rigorous exercise?
You may list, as students report out, the physiological changes to the respiratory, cardiovascular, neuromuscular, and urinary systems expected during strenuous exercise and as noted in the case of the cyclist, Joe. Students will respond with answers suggesting increases in heart rate, respiration, sweating and muscle fatigue, as well as muscle soreness as normal. However, in reality, in an effort to sustain maximum energy output over extended periods of time, endurance athletes train so that organ systems make the necessary physiological adaptations and are not subject to radical changes in function. Metabolic changes can occur with extensive endurance training in the muscles, hearts and lungs of the athlete, increasing efficiency of system utilization (Thompson, 2000).
In cycling, due to the posture of the athlete, increased arterial pressures in the lower limbs may cause both a pressure and volume overload on the heart (O’Toole and Douglas, 1995). Intensive training and long endurance events are accompanied by some muscle damage, due to decreases in myoglobin and build up of lactic acid in the tissue (Armstrong, 1986). The VO2 max (aerobic capacity) is important in the transfer of energy. This requires an integration of the respiratory, cardiovascular and neuromuscular systems. Mahler et al (1982) reported that the respiratory system is not a limiting factor in marathon runners, finding no difference between their respiratory function and that of their sedentary controls. Therefore only the cardiovascular and the neuromuscular systems adapt to endurance training.
2. List the symptoms Joe is