Increasing your swimming-specific maximal aerobic capacity (VO2max) is an important way to improve your swimming performances (1). In addition, your actual swimming velocity at VO2max (your vVO2max), which is defined as the minimal swimming speed which causes you to attain VO2max, is believed to be an incredible good predictor of your swimming prowess (better than VO2max by it-self), since vVO2max combines both aerobic capability and efficiency of movement in one physiological term. In effect, vVO2max indicates both how much aerobic capacity you have and how much you can get from your aerobic capacity (how fast you can move for a given rate of oxygen consumption). vVO2MAX TRAINING FOR SWIMMERS

The v in vVO2max is of course a function of how economically you can utilize oxygen. If you have a huge VO2max but you need all of your aerobic capacity to paddle along at piddling speeds, your vVO2max will be low (despite the high VO2max) and your performances poor. In contrast, an impressive vVo2max means that you have a lofty aerobic reserve and that you are nonetheless stingy with how you use oxygen; as a result, you can attain very high swimming speeds during competitions, because those speeds lie within your oxygen-consuming domain.

Naturally, then, a key goal of swim training is to heighgten vVO2max to the greatest-possible extent. Pioneering efforts by the great French exercise scientist Veronique Billat have shown that training at vVO2max is the most powerful way to improve the key variable. Veronique has demostarted that the utilization of a weekly interval workout, in which the work intervals are conducted at vVO2max, can lead to substanial improvements in vVO2max (and overall performance) in just six to eight weeks. A potential problem for you as a swimmer, however, is determining your actual vVO2max in the water.

You need to know what it is in order to set up intervals, but how do you properly estimate it? As you might expect, vVO2max can be measured directly in the pool using graded work intervals and sophisticated oxygen-measuring equipment, but such tests are extremely expensive, and the laboratories which have the capcity to carry out such exams may be inaccessible to you. Runners have had an easy (and cheap) way to figure out vVO2max, thanks to Veronique, who was able to show that something called TlimvVO2max averaged six minutes during running.  vVO2MAX TRAINING FOR SWIMMERS

TlimvVO2max (the "time limit at vVO2max") is simply the maximal amount of time a runner can keep going at vVO2max before falling over in a heap by the side of the track. Now, since TlimvVO2max averaged six minutes, this meant that a very simple test could provide a decent estimate of vVO2max. All a runner had to do was go to the track on a day when he/she was feeling good (and when environmental conditions were benign) and run at an all-out intensity for exactly six minutes.

The distance covered during the six-minute spurt could then be measured, and vVO2max could be reckoned. If a runner covered exactly 1600 meters in six minutes, for example, his/her vVO2max would be simply 1600m/360 secs = 4.44 meters per second. Often, the calculated vVO2max is converted to a tempo for practical use during training; in this case, 4.44 meters per second is the same as tempo of 90 seconds per 400 meters. But what about nanatorians? What is TlimvVO2max for an experience swimmer? This is the time that swimmers absolutely need in order to test themselves for vVO2max and then set up their vVO2max-enhancing work-outs.

Fortunately, a couple of scientific studies have looked at this very question, one of which was carried out by the redoubtable Veronique herself. In research completed in 1995, Billat and her coworkers directly measured TlimvVo2max in swimmers, as well as in cyclists, runners, and even kayak paddlers (2). Nine national-class swimmers were involved; their average age was 18 years, and their preferred competitive distance was 400 meters. Each swimmer performed two bouts of exercise to exhaustion, on separate days one week apart. vVO2MAX TRAINING FOR SWIMMERS

The first exam was designed to measure both VO2max and vVO2max; the second involved swimming for as long as possible at vVO2max in order to determine TlimvVO2max. The swimmers completed these tests in a flume in which the water-flow velocity could be adjusted by increments of .01 meters per second. Actual measurement of oxygen consumption was completed with a K2tm telemetric system.

To learn more about vVO2MAX training for swimmers (the full article can be read by purchasing Vol.1 Issue 6) and many more swimming related topics. Or enter any subject you wish to learn more about. 

During swimming workouts which last for about an hour or more, it is very important to ingest carbohydrate during the exertion. The ingested carbohydrate provides the fuel that muscles are looking for as they begin to run low on glycogen during the hour-plus effort, and research convincingly shows that such "exogenous carbohydrate" (carbs taken in during exercise) can increase the quality of the training session. With added carbs pouring into your system, you are simply able to swim faster: your muscles don't have to turn to speed slowing fat for energy as their internal carbohydrate stores diminish.

For the last 15 years or so, individuals who are knowledgeable about sports drinks have been saying that the practicalities of carb intake during swimming are no big problem. You simply find a good sports drink, a quaffable with a 5 to 9 percent carb concentration ( a drink with a less-than 5 percent content won't speed enough carbs to your muscles; at the other end, a beverage checking in at more than 9 percent might drag water into your tummy and increase  the risk of gastric distress). You take in about eight to 10 ounces (eight to 10 "regular swallows") of the stuff 10 minutes before you begin to swim, and you ingest five to six regular swallows every 12 to 15 minutes during your exertion. As a result, the carbs are absorbed at a steady rate and stream amply through your blood to your muscles, keeping them as happy as possible during your strenuous effort.

The eight- to 10-ounce pre exertion bolus is part of an effort to solve what has been believed to be the key limiting factor associated with carbohydrate intake during exercise: the limited rate at which fluids can pass from the stomach into the small intestine. Remember that no carbohydrate can be absorbed across the wall of the stomach, so getting sports drinks from the gullet into the small intestine is an essential part of moving carbs from their starting point in a sports-drink bottle to their demolition site in your muscles. Research has shown that the movement rate from tummy to intestine is dependent on the amount of fluid in the stomach; the more liquid present, the faster the movement rate. However, too much aqua in the stomach can produce gastric distress, so eight to 10 ounces has been viewed as an advantageous "load" to which most swimmers can become adapted.

The eight- to 10-ounce bolus also serves another purpose: it kick-starts the breakdown of exogenous carbohydrate. Some reports have indicated that the carbohydrate in the liquid bolus can begin to be metabolized for energy by muscles within five minutes after ingestion. In other words, the exogenous carbohydrate will start furnishing fuel for your muscles before your long workout even begins. This of course is great from the standpoint of glycogen-depletion prevention, and it is also "insurance policy" in case you begin your workout at too-fast a pace. Buzz-saw beginnings to long workouts tend to have a severely negative effect on muscle-glycogen stores, but this can be counteracted if the muscles are gulping sown exogenous carbs.

Until now, many scientists interested in carbohydrate intake during exercise believed that the bolus-plus-six-swallows-every 15 minutes strategy had solved the final problem associated with sports-drink ingestion, ensuring that the best-possible rate of carbohydrate delivery could be achieved. Now, however, there is an exciting new development in carbohydrate intake research. Outstanding investigator Asker Jeukendrup and his colleagues in the Human Performance Laboratory at the School of Sport and Exercise Science at the University of Birmingham in the United Kingdom have noted that another key limiting factor (for carbohydrate absorption during exercise) may be related to what are called intestinal transport mechanism. As you are probably aware, glucose, fructose, sucrose, and other carbohydrates can not move willy-nilly across the wall of the small intestine. Their movement from inside the hollow, coiled tube which call the small intestine into the small blood capillaries which will carry the carbs into the general circulation and thus to the muscles depends on "transport proteins" embedded in the walls of the small intestine. These proteins in effect help give carbohydrate molecules an inward directed "ride" through the wall of the gut and thus into the circulatory system (this process is a "transport mechanism").

Glucose absorption, for example, depends on a sodium-dependent glucose transporter called SGLT1 (sodium-dependent means that sodium must be present for SGLT1 to do its job, which is one key reason why sports drinks contain, sodium). Fructose, another simple sugar, seems to depend entirely for its absorption on something called GLUT-5 transporter, which is quite different from SGLT1. Somewhat surprisingly, the mechanism underlying the absorption of sucrose (aka table sugar), which is a disaccharide composed of one part glucose and one part fructose, is controversial. Some gutsy scientists argue that sucrose is simply hydrolyzed to glucose and fructose at the small-intestine's inner membrane, followed by absorption of the two constituents using SGLT1 and GLUT-5 transporters. However, there is some evidence that disaccharides-related transporters which are independent of SGLT1 and GLUT-5 (1).

Why go into all of that? Of course, there are not an infinite number of SGLT1 transporters lying around in the inner walls of the small intestine, nor is there a stupendous quantity of GLUT-5 carriers. In fact, the densities of these carriers appear to be rather moderate - good enough for the sofa spud who is watching the game of the week on television but perhaps not ample enough for the endurance athlete who wants to maximize the carb exit rate from the gut and subsequent entry into circulatory system during exercise. What may happen if a swimmers sports drink contains only glucose, for example, is that all of the SGLT1 carriers may become "busy" (i.e., attached to glucose molecules) as the swimmer moves along during his/her long workout. Other glucose molecules wait impatiently in the gut, nervously looking forward to their speedy passage to the muscles, but they can't move in because all of the transport "vans" in the intestinal wall are fully booked.

If this truly happens, then a drink which contains glucose and an additional carbohydrate (and thus which relies on both SGLT1 and a different type of transporter) Should work better (remember that the idea with sports drink ingestion is to maximize the rate, the higher the intensity of exercise which is permitted and the lower the risk that intramuscular glycogen depletion will hurt performance). A sports drink with two different types of carbohydrate might permit a much-speedier passage of carbs into the blood (since an increased number of transporters would be available). In theory, a beverage with three different types of carbohydrate would be better still.