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Running Research News And Events
March 17, 2010
PLANNING THE RIGHT TAPER: FAST, EXPONENTIAL DECAY MAY BE THE WAY
Almost all athletes and coaches agree that tapering - the reduction of training in a systematic way - is a good thing, because it ensures good recovery from heavy training (Gibla, M. et al., "The Effects of Tapering on Strength Performance in Trained Athletes," International Journal od Sports Medicine, Vol. 15, pp. 492-497, ) and is a key part of preparation for an important competition (Shepley, B. et al., "Physiological Effects of Tapering in Highly Trained Athletes, " Journal of Applied Physiology, 72, pp. 706-711, 1992). Unfortunately, there is a wide disagreement about how tapering periods should be constructed. These debates revolve around how long a tapering period should be, the extent to which training volume, intensity, and frequency should be reduced during a taper, and also - very importantly - the rate at which these variables should be reduced. PLANNING THE RIGHT TAPER
One dispute has centered around whether tapers should contain "step reductions" in training or "exponential decays." In a step reduction, total running is reduced by a certain amount, and the new volume of training is sustained throughout the tapering period. In an exponential-decay situation, the quantity of training decreases steadily over the course of the taper (there is no step-down in volume but rather a continuous slide), reaching bare-bones levels at the end of the tapering period. One popular step-down strategy is to clip training by 65 to 70 percent and then maintain the new, lower volume of work for one to three weeks. Traditionally, exponential decays have been linked with shorter durations of time, often four to eight days.
Until now, the relative merits of step-reduction and exponential-decay tapering have been poorly evaluated. Several years ago, outstanding tapering theorist Joe Houmard asked 5-K runners to cut training by 70 percent for three weeks (a step reduction). At the end of the 21-day period, the runners' 5-K race times were not significantly better, nor did the runners exhibit greater muscular power (Houmard, J. et al., "Testosterone, Cortisol, and Creatine Kinase Levels in Male Distance Runners during Reduced Training, " International Journal of Sports Medicine, Vol. 11, pp. 41-45). In contrast, a seven-day exponential decay in which training volume was reduced each day and overall weekly volume dropped by 85 percent produced dramatic improvements in 5-K race times and muscular power (Houmard, J. et al., :The Effects of Taper on Performance in Distance Runners," Medicine and Science in Sports and Exercise, Vol. 26, pp. 624-631).
This has led some tapering theorist to argue that when training volume is reduced aggressively and progressively to an extremely low level, performance is improved to a greater extent, compared with a single (or even several) step reduction over a more extended period of time. Some anti-step scientists even go on to argue that step reductions usually maintain performance but do not enhance it. PLANNING THE RIGHT TAPER
Such arguments are not completely fair, however, since step-reduction tapering has been linked with fairly impressive gains in physical capacity. For example, in a classic study carried out by renowned exercise physiologist Dave Costill in his laboratory at Ball State University, collegiate swimmers reduced training volume from 10,000 (1) to 3200 yards per day during a 15-day period (Costill, D. et al., "Effects of Reduced Training on Muscular Power in Swimmers," Physician and Sports Medicine, Vol. 13, pp. 94-100). After this 15-day step-reduction taper, the swimmers' performance times improved by 3.6 percent, their arm strength and power swelled by up to 25 percent, and blood-lactate levels were lower during 200-yard swimming "sprints." These results led Costill to recommend - in his fine book Inside Running: Basics of Sports Physiology - tapering periods of approximately two-weeks duration, with volume set at about one-third of usual levels (a large step reduction).
In later work, Raymond Kenitzer and Catherine Jackson asked 15 female collegiate swimmers to pare training volume by 60 percent over the four-week period (Kenitzer, R. and Jackson, C., "Blood Lactate Concentration in Female Competitive Collegiate Swimmers during End Season Taper, " Medicine and Science in Sports and Exercise, Vol. 21(2), p. S23). For the long distance swimmers involved in the study, volume dropped from 8000 daily yards to 3500 yards. During this step-reduction taper, blood-lactate levels fell steadily for about two and one-half weeks, and performance times both began to worsen. Kenitzer and Jackson drew the obvious conclusion: 60-percent, step-reduction tapers lasting up to 17 to 18 days are good things.
Step reductions can do more than maintain performance levels. However, the exponential cause was advanced pretty dramatically shortly after the publication of Kenitzer's work. Another scientist with a strong interest in tapering, Duncan MacDougall of McMaster University in Hamilton, Ontario (Canada), asked a group of well-conditioned runners who were averaging 45 to 50 miles of running per week to try out three different kinds of one-week tapers. The three strategies were:
(1) Doing nothing at all during the week (a 100 percent step-reduction),
(2) Running about 18 miles during the week at a leisurely pace, with a complete-rest day at the end of the week (1 64-percent step reduction), and
(3) Undergoing a drastic exponential decay in training over the week, with an emphasis on quality running. Using this strategy, the runners completed five hard 500-meter intervals on the first day of decay, four 500-meter blasts on the second day, 3 X 500 on day three, just 2 X 500 on day four, and a single 500-meter surge on day five. After a rest on day six, they were ready to be tested on day seven (as were the employers of strategies one and two). Importantly, each 500-meter interval was performed at about one-mile race pace, and since the runners warmed up with 500 meters of inchmeal running before the quality intervals were undertaken, the total training volume for the week was about 10K, or just over six miles. Thus, this decay involved an overall 87- to 88-percent reduction in training (MacDougall, D. et al., "Physiologic Effects of Tapering in Highly Trained Athletes," Medicine and Science in Sports and Exercise, Vol. 22(2), Supplement, #801). PLANNING THE RIGHT TAPER
The performance test on day seven involved running as far as possible at one-mile race pace, and the 64-percent-step-reduction runners did fairly well, advancing endurance time at this speed by 6 percent (the 100-percent-reduction runners failed to improve at all). However, the exponential runners blew the roof off MacDougall's lab, raising endurance time at one-mile pace by a full 22 percent! The expo folks also possessed enhanced leg-muscle enzyme activity, augmented total blood volume, increased red-blood-cell density, and greater muscle-glycogen storage, compared to the step-reducing runners.
These results certainly made exponential-decay tapering look better than step-reduction plans, but a few comments are in order. First, note that MacDougall's decaying runners employed a relatively high quantity of quality running during their taper - about 7.5 kilometers out of a total volume of 10K (75 percent). It is possible that the 64-percent-step-reduction runners would have fared far better if they had been able to include quality work in their training as well.
In addition, the expo-decay runners trained during their taper week at exactly the pace which was utilized for testing. Thus, their tapering period was highly "neural," i.e., it "tuned up" their nervous systems and prepared their neuromuscular systems for the exact intensities and most-efficient patterns of coordination and overall movement which would be used in the test. As you can see, MacDougall's work did not really compare step-reduction tapering with exponential-decay cutbacks but instead merely contrasted two widely disparate tapering plans.
Nonetheless, MacDougall's unique exponential plan looked mighty good, and further work by Joe Houmard and his colleagues added weight to the idea that tapering should proceed along a "steep-slide" course. Inspired by MacDougall (Houmard had used the Ontario taper to prepare very successfully for a marathon), Houmard asked eight experienced runners (six males and two females) who had been running about 43 miles per week to abbreviate their running to 6.2 miles of interval training and seven miles of jogging. Almost all of the interval training consisted of high-intensity, 400-meter intervals at about 5-K race pace or slightly faster. PLANNING THE RIGHT TAPER
The exponential part of the plan was modeled along MacDougall lines: On the first day, the runners completed eight 400-meter intervals, on the second day they clipped off 5 X $00, on day three they hit 4 X 400, and on day four they tried 3 X 400, followed by 2 X 400 on days five and six and 1 X 400 on day seven. During the workouts, recovery intervals (composed of walking or resting) lasted just long enough to let heart rates drop to 100 to 110 beats per minute, and an 800-meter easy jog was performed both as a pre-workout warm-up and post-training-session cool-down (this accounted for the seven miles of jogging for the week). A control group of eight runners maintained their usual training volume of 43 miles per week.
When a 5-K race was held on the eighth day of the study (the day immediately following the one-week taper), the exponentially-advantage runners trimmed average 5-K times by statistically significant 29 seconds, from 17:16 to 16:47 (all eight of the runners were able to improve their clockings). The exponentially- tapered folks also improved running economy by a rather dramatic 6 percent, while the control group improved neither economy nor 5-K performance.
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