stroke and swim workout question

Jean, I realize that my explanation is too simple. However, I have the same problem with your description of aerobic and anaerobic swimming. As I understand it, whenever a muscle contracts it initially gets its energy anaerobically from stored glycogen. As exercise is prolonged, the muscle takes energy aerobically from oxygen in the bloodstream, provided by the cardiovascular system. As the intensity of the workout increases, the muscles begin using more of their stored glycogen for energy, working anaerobically. The anaerobic process produce lactic acid, which is continually removed between contractions and the muscles recharged for the next burst of energy. At some point more lactic acid is produced than can be removed, and it begins to build in the bloodstream. The point that lactic acid is present in the bloodstream is called the anaerobic threshold. My understanding of the term "oxygen debt" is that it usually refers to exceeding the AT. Now, the problem I have with your explanation is that it seems to imply an "either/or" situation: that a swimmer's muscles are powered exclusively aerobically until the AT, then exclusively anaerobically afterwards; that the anaerobic system doesn't kick in until the AT. That is simply not the case. The muscles are always getting some energy from oxygen in the bloodstream (aerobically), even after the AT; and any exertion at all of a muscle will call upon the stored glycogen to power the muscle anaerobically, before the body reaches the anaerobic threshold. We characterize different exercises as "aerobic" or "anaerobic" based upon the predominant method called upon to power the muscles. Running is predominantly aerobic, although there's an anaerobic component. Weightlifting is predominantly anaerobic, long before one reaches the AT, although there is a very small aerobic component. Nearly all kinds of swimming, however, are both aerobic and anaerobic. Sprinting may be more anaerobic than a distance workout, but a sprinter's workout has a large aerobic component none the less. Distance swimming may be more aerobic than sprinting, but it likewise has a large anaerobic component, before one ever reaches the AT, as the muscles are exerted on each stroke. To tie all this into my first, oversimplified explanation, exercise that is characterized as "aerobic" uses large groups of muscles at an intensity below the AT to tax the cardiovascular system by making it supply the muscles with oxygen. Exercise that is characterized as "anaerobic" usually places stress against individual muscles to make them burn the glycogen out of them, helping to build strength and size. Swimming does both, throughout the intensity range.

Jean, I realize that my explanation is too simple. However, I have the same problem with your description of aerobic and anaerobic swimming. As I understand it, whenever a muscle contracts it initially gets its energy anaerobically from stored glycogen. As exercise is prolonged, the muscle takes energy aerobically from oxygen in the bloodstream, provided by the cardiovascular system. As the intensity of the workout increases, the muscles begin using more of their stored glycogen for energy, working anaerobically. The anaerobic process produce lactic acid, which is continually removed between contractions and the muscles recharged for the next burst of energy. At some point more lactic acid is produced than can be removed, and it begins to build in the bloodstream. The point that lactic acid is present in the bloodstream is called the anaerobic threshold. My understanding of the term "oxygen debt" is that it usually refers to exceeding the AT. Now, the problem I have with your explanation is that it seems to imply an "either/or" situation: that a swimmer's muscles are powered exclusively aerobically until the AT, then exclusively anaerobically afterwards; that the anaerobic system doesn't kick in until the AT. That is simply not the case. The muscles are always getting some energy from oxygen in the bloodstream (aerobically), even after the AT; and any exertion at all of a muscle will call upon the stored glycogen to power the muscle anaerobically, before the body reaches the anaerobic threshold. We characterize different exercises as "aerobic" or "anaerobic" based upon the predominant method called upon to power the muscles. Running is predominantly aerobic, although there's an anaerobic component. Weightlifting is predominantly anaerobic, long before one reaches the AT, although there is a very small aerobic component. Nearly all kinds of swimming, however, are both aerobic and anaerobic. Sprinting may be more anaerobic than a distance workout, but a sprinter's workout has a large aerobic component none the less. Distance swimming may be more aerobic than sprinting, but it likewise has a large anaerobic component, before one ever reaches the AT, as the muscles are exerted on each stroke. To tie all this into my first, oversimplified explanation, exercise that is characterized as "aerobic" uses large groups of muscles at an intensity below the AT to tax the cardiovascular system by making it supply the muscles with oxygen. Exercise that is characterized as "anaerobic" usually places stress against individual muscles to make them burn the glycogen out of them, helping to build strength and size. Swimming does both, throughout the intensity range.