A key transition point in swimming has often been called the "anaerobic threshold." In fact, you can't be a real swimmer until you have used the term "anaerobic threshold" in a sentence at least once. And-you can't be a truly hip swimmer until you have advised a swimming friend that the concept of an "anaerobic threshold" is hopelessly out of date. Swimming's AnT and AT

f you are a regular reader of Swimming Research News, you know that - back in the dark, early days of exercise science - the phrase "anaerobic threshold" was minted to denote an exercise intensity at which there was a systematic rise in blood lactate. It was thought that this was the result of hypoxia (low oxygen) in the muscles, and thus the word "anaerobic" (without oxygen) seemed appropriate.

A lackadaisical anaerobic threshold (i.e., a case in which blood lactate began to pile up at a slow swimming speed) was viewed as a bad thing, and the remedy was usually thought to be high-volume training, which was supposed to enhance the functioning of the cardiovascular system and improve the delivery of oxygen to the muscles (and the utilization of oxygen once it got there). As you can see, this seemed to make sense: If anaerobic threshold occurred because of a lack of oxygen, then swimmers should do things which ensured that lots of oxygen would be flowing toward their muscles. What could be better for the heart and the oxygen-delivering blood capillaries than swimming for tons of meters?

However, such conceptions ignored the simple and unavoidable facts that anaerobic threshold occurs at just 50 percent of max aerobic capacity in many untrained individuals and at 85 percent of max aerobic capacity in a large number of elite swimmers - in other words in situations in which oxygen is quite plentiful and the oxygen-delivery-and-utilization system has not been taxed to its limit. It's clear that the anaerobic threshold is not caused by a lack of oxygen in the muscles, and thus we shouldn't call our transition point an "anaerobic" threshold. The term "lactate threshold" is a much-more appropriate descriptor of the swimming intensity above which lactate begins to accumulate; it carries with it no inappropriate implications about a lack of oxygen. Swimming's AnT and AT

ecent research suggests that the real "problem" which produces the lactate threshold actually is unrelated to oxygen delivery and in fact resides in the "shuttle systems" which exist in the walls of muscle-cells' mitochondria. To understand how this works, it is important to know that within muscle cells molecules of an important chemical called NAD work as "carriers". The job of these NAD carriers is to pick up high-energy hydrogens (which have been stripped away from carbohydrate molecules, for example) and then carry them to the "shuttle mechanism" in the walls of the mitochondria. The hydrogens can then say good-bye to the NAD which brought them, shuttle through the mitochondrial walls, and move inside the mitchondria.

In the presence of oxygen, the energy contained in these hydrogens is then transformed into ATP, which furnishes the actual energy the muscles must have in order to contract and thus perform the work of swimming, if the shuttle mechanisms are operating too slowly during exercise, NAD takes some of the hydrogens which should have been dropped off at the mitochondrial walls and instead donates them to a chemical called pyruvate, thus forming lactic acid. As lactic acid accumulates, it can begin pouring out of the muscles into the blood. If this outpouring of lactic acid is not balanced by increased uptake by other muscles and the heart, blood-lactate levels increase, and a lactate threshold has been crossed.
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    Many runners, both at the elite and recreational level, think nothing of training for and competing in a 10-K run. Until recently , however, swimmers avioded the 10-K swim  distance, thinking of it as too lengthy for serious consideration. SECRETS

    Historically, long distance swimming has been viewed as an act of individual courage and determination, rather than a competitive event. 130 years ago, endurance swimming captivated the imaginations of large numbers of individuals in Europe and the United States, and many persons were not afraid to take on the challenge of swimming solo in the water over extended distances. In 1875, Captain Matthew Webb made the first successful swim across the 34-K-(21-mile-) wide English Channel, and in the same year Agnes Beckwith swam six miles in the Thames River. Since then, many athletes have attempted to establish new distance-swimming records, breaking previous times and crossing different bodies of water around the world while swimming alone. In fact, swimming across the English Channel has been attempted thousands of time - and completed hundreds of times - since 1875.

    In very recent times, open water swimming and racing over substantial distances have become organized sports and are becoming much more "mainstream." The 10-K competitive swim will be introduced for the first time at 2008 Olympics in Beijing. In the United States in 2006, the 5-K, 10-K, and 25-K Open Water Championships were held in Fort Myers, Florida in the beginning of June, and the Masters' Open Water Championships were completed inAugust and September in Colorado and Illinois, respectively. Internationally, there are calendars of open-water races at assorted distances throughout the year.

    According to definitions created by FINA (the Federation Internationale de Natation, which is the international governing body of competitive swimming), long-distance swimming in any distance in open water up to 10 kilometers, whereas marathon swimming is defined as any open-water competitive swimming event which is longer than 10K (please see http://www.fina.org) . For many open water races, especially those at longer distances, escort crafts (usually kayaks or other small boats) are mandatory and are assigned to each racer for safety, as well as support. In organized, FINA-sanctioned races, there are many rules for swimmers to follow. Here is a short breakdown of the rules: SECRETS

(1) Wetsuits are not allowed.

(2) Swimmers are not permitted to draft or pace off of their safety crafts or other swimmers.

(3) Swimmers can not intentionally make contact with their escort boats or with craft crew member.

    To avoid violations and potential disqualifcation, the escort craft crew as well as the swimmers themselves must be familiar with the rules. The following are some general guidelines:

(1) The escort crew should be aware of signs and symptoms of potential dehydration, exhaustion, and hypothermia.

(2) The crew must avoid paddling in front of the swimmer and thus creating a slip stream.

(3) In order to give a swimmer food and drink, crew members should attach such items to a string and throw them to the swimmer (in order to avoid direct contact).

(4) Craft crew are allowed to give the swimmer instructions and verbal feedback.

    Clearly, long-distance and marathon swimming races require lots of planning and forethought, from logistical standpoint as well as from a training perspective. One of the key problems in preparing for a 10-K race is estimating an appropriate goal speed. Such an estimation will boost training preparations for the event (because long swims can be conducted at the appropriate, race specific intensity) and will also permit the establishment of an appropriate swimming speed (not too fast, not too slow) during the actual competition.

    In 1981, Pete Riegel wrote a fascinating article in which he presented an equation which produced extremely accurate predictions of pace in competitions lasting from 3.5 to 230 minutes (1). What was unique about Riegel's approach was that he found linear relationships between the logaithms of time and distance in multiple endurance sports, including running, swimming, cycling, Nordic skiing, race-walking, and endurance skating. Riegel based his work on world-record performances, and the equation he developed is as follows:

    T=axb

    T stands for the time in minutes, x is the distance of the competition in kilometers, and a and b are constants which are unique to each activity and are different for age groups in running. SECRETS

    Although Riegel's equation for endurance swimming was only based on records within the range of 3.9 to 16 minutes, it is accurate for longer distances as well. Utilizing this equation to predict a 10-K swim performance, the proposed constants (a = 9.936 for men and 10.578 for women; b = 1.02977 for men and 1.03256 for women) should work in cases in which swimmers are attempting to set world records. In the 2005 FINA Championships (also known as the World Aquatic Championships), the men's winner of the 10-K swim, Chip Peterson, finished in a time of 1:46:38, while the women's champion, Edith van Dijk, had a 1:56:00 finish. These are very close to the Riegel- equation predictions of 1:46 for men and 1:54 for women.

    Bear in mind, however, that Riegel's equation is not applicable to those of us who are not contending for a world record, primarily because our fatigue indices (the constants a and b) are greater, compared with those of world-record setters. Fortunately, other methods of predicting performance times have been created. SECRETS