Many experienced swimmers train two times a day, and the basic argument supporting such twice-a-day training has been that it is a practical way to boost total training volume. The extra volume is then supposed to improve "strenght" in some unspecified way and lead to upswings in aerobic capacity.

Such pro-double-workouts contentions have been strictly theoretical in nature, of course. Until recently, no scientific research had ever detected special benefits associated with two-sessions per day training.

But that is all changed now: There is solid, scientific evidence that two-a-days can be beneficial - thanks to a unique physiological mechanism. Brand-new, about-to-be published research indicates that the strategy of conducting two workouts per day can activate special genes in an athlete's muscles, genes which cause the production of proteins which fight fatigue and prolong endurance during high-quality exertions. As the investigation reveals, higher performances are the end result.

To learn more about Are "Two-A-Days" Good For Competitive Swimmers? (the full article can be read by purchasing Vol.1 Issue 7 of Swimming Research News) and many more swimming training topics, simply enter two a days good for competitive swimmers in the "Search-Archives" box to the right. A subscription to Swimming Research News is another way to receive valuable information about swimming. Two-A-Days

Negative splitting (completing the second half of a race more quickly than the first half) seems to produce the best-possible performances in running and cycling competitions, but is this also true for swimming? Many successful swimmers "positive split" their races, completing the first half of the race more swiftly than the second, suggesting that perhaps negative-splitting does not work effectively in the water. One analysis indicated that split times at the half-way points of swim races are often two to three seconds faster than the times for the second halves of the competitions (1). Another study revealed that national and international 100- and 200-meter breast-stroke swimmers utilize a faster velocity over the first halves of their races, compared to the second halves (positive splitting) (2).Does Positive Splitting Give Swimmers More Pop In Their Performances?

Nonetheless, scientific evidence seems to be tipped in favor of negative splitting. The scientific foundation for the strategy was firmly laid slightly more than 10 years ago at the Sinai Samaritan Medical Center in Milwaukee, Wisconsin, where Carl Foster and his colleagues put nine well-trained athletes through their paces (3). In Foster's work, the athletes took part in five different 2000-meter time trials, completing the first kilometers of the test at different percentages of their 2-K personal-record paces. They tried covering the initial kilometer at 56, 53, 51. 50, and 48 percent of the average clocking per kilometer established during their 2-K PRs; of course, the 56-, 53-, and 51-percent beginnings represented relatively slow starts (negative splitting), the 50-percent start represented an attempt at even pacing, and the 48-percent outburst was a fast start (positive splitting). In all cases, the second kilometer of the trial was completed as quickly as possible; the overall times were compared after all of the tests were performed.

As it turned out, the moderately slow start - the 51- percent stratagem - produced negative splits for the 2-K trials and the best average performance times, beating the other techniques by about 2 percent! In addition, out of nine new 2-K PRs set during the test, five were associated with the 51-percent beginning, and none were the result of a fast start (48-percent strategy), even though rapid starts are extremely popular among endurance athletes in general. In the Foster study, even splitting (completing a 50-50 race) also appeared to be better than positive splitting.

It is important to note, though, that although starting a bit slowly was good in the classical Foster work, overly slow beginnings were decidedly sub-optimal. Beginning the time trials at 53 or 56 percent of the PR one-kilometer clocking often produces mediocre finishing times (although truthfully they were no lousier than the 48-percent start), probably because it was just too difficult to make up the time "lost" during the first half of the trial. Slightly slow (51-percent) starts were best - far better than the rapid (48-percent) initial surges.Does Positive Splitting Give Swimmers More Pop In Their Performances?

Why do fast starts work rather abysmally in cycling and running? No one knows for certain, but logical theory is that very intense running or cycling at the beginning of a race or workout - carried out before the cardiovascular system has a chance to flood the muscles with oxygen - may lower the pH inside leg-muscle cells and spike inorganic phosphate levels enough to heighten fatigue and thus harm performance. This early fatigue seems to linger into the final portion of a competition or intense workout, even when an athlete slows down appreciably. In contrast, slower beginnings allow muscle cells to take in huge volumes of oxygen before the really hard work begins, attenuating the decline in pH and increasing fatigue-resisting, aerobic energy production.

The potential deplorability of fast starting was demonstrated in Sid Robinson's classic research carried out in the 1950s. Sid simply asked a group of experienced runners to cover 1245 meters in two different ways: In one case, they ran at the sizzling pace of 13.9 miles per hour (4:18 per mile) from the get-go, simply holding that pace until the 1245- meter point was reached - in a time of about 3:20. On a different occasion, the runners started more cautiously, cruising along at only 13.5 mph (4:27 per mile) before turning on the jets and running at 14.9 mph to reach the 1245-meter finish line in the same time - 3:20. Although the total time spent running was the same in the two cases, the slower-start strategy produced a key advantage - a diminished average rate of oxygen consumption (that is to say, better average running economy). Had the runners been able to compete with themselves, using the slow vs. sizzling starts in the races lasting from 1500 to 3000 meters or so, the improved economy would have given the slow starts (potential negative-splitters) faster times (it's likely that the enhanced economy would have limited fatigue, down-graded perceived exertion, and permitted the slow starts to continue running at a fast pace for a longer period of time).

On yet another occasion, Robinson let his runners start at 14.9 mph and then slow down to 13.5 (remember that he had also tried the reverse - a 13.5 start and then a 14.9 follow-up). This fast-starting scheme led to real disaster, with oxygen consumption going through the roof and performances plummeting (4). Does Positive Splitting Give Swimmers More Pop In Their Performances?

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