Question #2:
How does metabolic stress limit endurance performance? Discuss specific physiological limiters relating to metabolic stress. Endurance exercise is known to cause metabolic stress due to the increased rate of oxygen consumption. With an increase in oxidative respiration, a greater amount of electrons pass through the electron transport chain amplifying free radical production. These free radicals are called reactive oxygen species (ROS) and can set off chain reactions damaging other cells. With an adequate antioxidant supply, an electron can be donated to the free radical silencing it. ROS are not an issue at rest or during normal exercise since levels produced do not exceed the body’s anti-oxidant supply. Endurance running challenges …show more content…
Forty-six ultra-runners were tested before, during, and immediately after the 330-km Tor des Geants trail race in France. Only twenty-five of the runners completed the race and provided post race urine and blood samples. Of the finishers, post-race ROS levels increased significantly with respect to both pre-race (p<0.001) values. Antioxidant capacity increased between pre and mid-race values before declining to notably lower antioxidant availability post-race. ROS production was significantly higher at the mid-race mark in the athletes that did not finish the race compared to those who did (Mrakic-Sposta et al., 2015). Up until the middle of the race, athletes were able to combat increasing levels of ROS as seen in the increased antioxidant capacity. However, by the end of the race and after 110+ hours of running, ROS production surpassed the antioxidant defense system of the body allowing for oxidative damage to occur. It is possible that the athletes who did not finish the race succumbed to the metabolic stress of higher ROS levels than the rest of the competition. When endurance exercise creates ROS in levels not tolerated by antioxidant availability, metabolic stress becomes evident and performance is …show more content…
Creatine kinase (CK) is a well-known marker for muscle tissue damage and can be measured in an athlete’s blood serum. A study assessed muscle damage in sixteen of the world’s best ultra-runners during the 2012 Western States Endurance 100-mile run. Blood samples were collected the morning of, immediately after, as well as one and two days post race. CK levels immediately after the race were dramatically increased from pre-race values. Levels remained heightened above pre-race values for one and two days following the race. Myoglobin levels were also significantly elevated after the race and continued to remain significantly higher two days post event (Kupchak et al., 2013). Myoglobin is found in the blood of skeletal and cardiac muscle when damage to tissue occurs through myocardial infarction or in the case of skeletal muscle, prolonged vigorous exercise. Both CK and myoglobin muscle damage markers were significantly increased in these highly trained ultra-runners proving the effects of metabolic stress on race performance and
How does metabolic stress limit endurance performance? Discuss specific physiological limiters relating to metabolic stress. Endurance exercise is known to cause metabolic stress due to the increased rate of oxygen consumption. With an increase in oxidative respiration, a greater amount of electrons pass through the electron transport chain amplifying free radical production. These free radicals are called reactive oxygen species (ROS) and can set off chain reactions damaging other cells. With an adequate antioxidant supply, an electron can be donated to the free radical silencing it. ROS are not an issue at rest or during normal exercise since levels produced do not exceed the body’s anti-oxidant supply. Endurance running challenges …show more content…
Forty-six ultra-runners were tested before, during, and immediately after the 330-km Tor des Geants trail race in France. Only twenty-five of the runners completed the race and provided post race urine and blood samples. Of the finishers, post-race ROS levels increased significantly with respect to both pre-race (p<0.001) values. Antioxidant capacity increased between pre and mid-race values before declining to notably lower antioxidant availability post-race. ROS production was significantly higher at the mid-race mark in the athletes that did not finish the race compared to those who did (Mrakic-Sposta et al., 2015). Up until the middle of the race, athletes were able to combat increasing levels of ROS as seen in the increased antioxidant capacity. However, by the end of the race and after 110+ hours of running, ROS production surpassed the antioxidant defense system of the body allowing for oxidative damage to occur. It is possible that the athletes who did not finish the race succumbed to the metabolic stress of higher ROS levels than the rest of the competition. When endurance exercise creates ROS in levels not tolerated by antioxidant availability, metabolic stress becomes evident and performance is …show more content…
Creatine kinase (CK) is a well-known marker for muscle tissue damage and can be measured in an athlete’s blood serum. A study assessed muscle damage in sixteen of the world’s best ultra-runners during the 2012 Western States Endurance 100-mile run. Blood samples were collected the morning of, immediately after, as well as one and two days post race. CK levels immediately after the race were dramatically increased from pre-race values. Levels remained heightened above pre-race values for one and two days following the race. Myoglobin levels were also significantly elevated after the race and continued to remain significantly higher two days post event (Kupchak et al., 2013). Myoglobin is found in the blood of skeletal and cardiac muscle when damage to tissue occurs through myocardial infarction or in the case of skeletal muscle, prolonged vigorous exercise. Both CK and myoglobin muscle damage markers were significantly increased in these highly trained ultra-runners proving the effects of metabolic stress on race performance and