Scientific studies have shown that 'tapering' - reducing one's training for one to three weeks prior to competition - can produce dramatic improvements in performance but haven't been sure exactly why this is so. Now, recent research from the University of Puerto Rico Medical School shows that tapering boosts competitive efforts by increasing the elasticity of muscles, or, more precisely, by enhancing the way in which muscles use 'stored elastic energy'.

'Stored elastic energy' may sound like a mouthful, but it's easy to understand. When a muscle is stretched (as it usually is before it contracts), it contains more energy than it does when it's non- stretched, just as the rubbery part of a catapult contains more energy - and can hurl an object faster and farther - when it is in the fully stretched position. This energy which is stored in a muscle is extremely useful to the athlete, because it helps the muscle shorten (contract) powerfully without the need to burn up further energy.


Boosting power, saving energy
For example, when a soccer player runs toward the goal, the hamstring muscles are stretched each time a leg swings forward. This pre-stretch gives the hamstrings a boost when they contract, rocketing the leg backward, and thrusting the player toward the ball or the goal. Pre-stretching a muscle is a great way to boost muscle power output, and save energy

The way in which the energy put into a stretched muscle is used to produce raw power - and thus greater footspeed, a more forceful, quicker push on the bicycle pedals, or a more puissant swimming stroke - is simply called the utilisation of stored elastic energy (USEE). The better the utilisation, the more powerful and efficient the athlete.

At the University of Puerto Rico, 29 young swimmers undertook a 21-day taper. USEE was evaluated four times: before the taper began, at the end of seven days of tapering, after 14 days, and again following the full 21 days of tapering. Interestingly enough, USEE actually decreased by about 25 per cent after seven days of tapering, indicating that a seven-day taper was too short.

Best after 21 days - or longer?
However, compared to the beginning of the tapering period, USEE had risen by about 17 per cent after 14 days of tapering (and by about 55 per cent compared to one week earlier). By far the best tapering period for enhancing USEE, though was the 21-day taper, which bolstered USEE by an amazing 125 per cent!

Why did tapering upgrade USEE? Probably the swimmers' muscles were sore and stiff following their regular training, and this stiffness interfered with optimal USEE. It apparently took at least 14 days of tapering for muscles to recover enough so that USEE could improve, but the true mega-move in USEE took a total of 21 days (there was no word on whether USEE might improve even more with an even longer taper).

The implications of the research are clear: one reason that the strategy of tapering works is that it makes it possible for muscles to optimise their USEE, although it seems to take at least 21 days for this optimisation to work in swimmers. Tapering does lots of other useful things, too (see our full review in Issue 57), such as boosting carbohydrate levels in muscles, hiking blood volume, creating augmented levels of aerobic enzymes inside muscles, and speeding muscle repair. Endurance athletes should remember that the more difficult their training has been, the longer and more dramatic should be their taper. Athletes who have engaged in fairly strenuous training probably need at least three weeks of tapering prior to competition, while heavy-duty marathon training makes at least a one-month tapering period necessary. ( 'Effects of Taper on Stored Elastic Energy in Adolescent Swimmers, ' Medicine and Science in Sports and Exercise, vol. 27(5), Supplement, no. 510, p. S90, 1995)