Does this mean we've reached a plateau in terms of speed?
"At some level we've reached a physiological plateau. In general, the champions of today don't have dramatically better treadmill times as compared to elite athletes of earlier generations. What I think we are seeing is a small effect due to better racetracks, shoes and improved sports medicine. And, people are participating longer, so you have more competitive depth which leads to better races and races designed to set world records," Dr. Joyner says.
The Physiology of Performance
In endurance sports such as running a marathon, there are three physiological determinants of performance: maximal oxygen uptake (also called VO2 max), lactate threshold and running economy (sometimes called running efficiency).
Maximal oxygen uptake is the maximum capacity for oxygen consumption by the body during peak performance. It is also a measure of aerobic fitness. Generally, the higher the VO2 max during peak performance, the better the cardiac output - which means the heart is bigger.
In a treadmill test of two young men - one, an athlete, and the other, not - the athletic male generally has a VO2 max value of between 70 and 85 milliliters (ml) of oxygen per kilogram per minute, as compared to 45 in the sedentary male, Dr. Joyner says.
What fraction of your VO2 max you use over a period of time can depend on your lactate threshold, which is considered a marker of maximum steady-state performance for athletes in endurance events.
"The lactate threshold is highly related to how people perform in an event like the 10,000-meter race, marathons or a bicycle time trial. The physiology and biochemistry behind it is complex and controversial, but it's a good marker of when the regulatory and physiological control systems of the body are in balance," Dr. Joyner says.
Old Wives' Tales - The Lactate Threshold
Intense exercise causes lactic ac
|Contact: Amy Reyes|