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Banister's system rewards intense training but ignores specificity
There are good and bad things about Banister's system. One good feature is that it tends to reward intense training. For example, still using the above max and resting heart rates, let's compare a workout at 150 beats per minute with an equal length session at only 75 beats per minute. If we just counted heart beats, then the 150 workout would be twice as good as the 75 session, but with the Banister scheme the 150 workout gets an intensity value of 0.67, since it is two-thirds of the way between resting and max heart rates, and the 75 effort gets a rating of only 0.17, since it is one-sixth of the way. Thus, Banister would assign a 150 workout 0.67/0.17 - four times the value of a 75 session. The Banister system penalises sauntering and rewards
full-tilt exertion, which makes good physiological sense.
Another good thing about the Banister scheme is that it allows you to attach a specific number to each workout and to a weekly training load (or some other training cycle if you do not like to use weeks) - a number which takes into account both the intensity and length of your training sessions. That adds a bit of precision to your training, allows you to determine how much your training is really increasing (or decreasing) when you make changes, and also enables you to compare various parts of your training history: for example, you might want to take a close look at your weekly TRIMP values for a significant personal best.
Unfortunately, though, there are several key problems with the Banister scheme: for one thing, it revolves around heart rate, which is sensitive to a multitude of factors and may not accurately reflect intensity on a particular day; for example, heart rate might be high on a hot, humid day, even though running or cycling speed is rather low. The Banister plan also fails to take into account the specificity of training needed for a particular event. For example, someone training 600 minutes per week at an average heart rate of 140 beats per minute would tend to end up with dramatically bigger TRIMP values than someone else working out for 240 minutes at 170 beats per minute. If both individuals were training for a 5k, however, and 25% of the latter runner's training was at 5k speed while only 5% of the former runner's workouts fell into this category, the runner with the lower TRIMP would actually be better prepared for the race.

When four tapering strategies were compared, here's what they found
We thank Banister for his efforts, though, and especially appreciate his new research on tapering(9), in which he attempts to predict the extent to which performance will be improved following different kinds of tapering periods. He uses a systems model of training(10) to predict performance by transforming daily TRIMP scores into separate daily tallies of fitness and fatigue, during both regular training periods and subsequent tapers. He then examines the reliability of these predictions in a real-life field trial with 11 triathletes, who train for 94 days, with an additional tapering period, in an effort to optimise performance. In this new work, Banister employs an 'intensity factor' called Y, which is based upon the rise in blood lactate levels during a particular workout, to give even more credit to intense training. In effect, he calculates TRIMP with the equation TRIMP = D (duration of workout in minutes) multiplied by A/B multiplied by Y. In this equation, D is the training volume component and (A/B) x Y is the intensity component.
The triathletes, all male, had an average age of 26 and mean body fat levels of 8.7%. During the study, the athletes employed a total of four different tapering programmes, with one group of five using two strategies and the other group of six trying another two, as follows:

a single-step reduction plan, maintaining 22% of regular training volume over a two-week period
a 'medium' exponential decay taper, cutting training volume to a modest extent each day over a two-week period, with total tapered training averaging about 30% of normal
a 'slow' exponential decay taper, trimming training volume by a very small amount per day over a two-week period, so that total tapered training volume was about 50% of normal
a 'fast' exponential decay tapering plan, slashing training volume more aggressively each day.

The overall protocol was this: all 11 athletes trained in a standard way for 31 days, then five athletes used taper-plan 1, while the other six employed plan 2. The two weeks of tapering were followed by a four-day break of unstructured training. Regular, strenuous training was then resumed for 33 days, the athlete cohort was reconstituted, and five athletes tried taper 3, while the other six used taper 4. Thus, the comparisons were between step reduction tapering and a medium exponential decay taper, and also between slow and fast exponential decay tapering.
Banister's model predicted that medium exponential decay tapering would beat the step-reduction stratagem, and indeed it did. The medium decay triathletes improved 5k running performance from 1149 seconds (19:09) to 1103 seconds (18:23), from just before tapering began to close to the end of the two-week tapering period. Meanwhile, the step reduction triathletes reduced 5k time by an average of 13 seconds, which was not statistically significant.
The athletes were also tested to exhaustion on a cycle ergometer. For this test, the triathletes warmed up for four minutes at a work rate of just 30 watts, then exercise intensity was increased by 30w per minute until an athlete was exhausted or unable to maintain a pedal rate above 80rpm. For this test, the exponential decay also proved to be superior: athletes using exponential decay advanced their maximal power from an average of 423 to 446w, while step reduction triathletes moved from 412 to 418w. Both changes were statistically significant, but the upswing in power was significantly greater for the exponential decayed athletes.
Decay tapering really does maximise physiological improvements
A beautiful feature of Banister's research was that the intensity component of training ((A/B) x Y) was similar for both plans and for the regular training which preceded the tapers. The exponential reduction in training was achieved solely by a reduction in the duration of training sessions or the frequency of sessions per week. Thus, improvements in performance for the exponential decay group could not be attributed to higher intensity of training within the tapering period, or even to the inclusion of slightly more volume within the tapering plan - a difference which was not statistically significant. Decay tapering really was better than stepping down training with a single blow.
Comparison of tapering plans 3 and 4 also produced very interesting results. Banister's modelling predicted a superiority of the latter over the former - and again he was on target. For the cycle ramp test, slow decay triathletes improved max power from 394 to just 409w - a 4% increase - while fast decay athletes jumped from an average of 433 all the way to 467 watts - a significantly better 8% climb.
The trend was in the right direction for the 5k runs, too, with 5k time improving from 1159 seconds (19:19) to 1131 seconds (18:51) for the slow decayers (a 28-second and 2% improvement), and from 1167 seconds (19:27) to 1093 seconds (18:13) in the fast decay group (a 74-second and 6% change). However, these differences were not statistically significant.
As Banister points out, athletes train to improve physical performance, but initially the opposite response occurs, in that a significant increase in training actually induces greater levels of fatigue and poorer performances. It is left for the taper period to reveal the extent of the actual physiological improvements induced by the hard work. The tapering period must be constructed to maximise these physiological improvements, and it appears that exponential decay tapers are able to do this.
What would such a taper look like? First, there would be no loss in intensity, compared with regular training: in fact, Houmard's and MacDougall's work indicate that average training intensity should increase; secondly, the taper would have a decay pattern rather than a step reduction look; finally, fast decays seem to be better than slow ones, based on Banister's experiments. This simply means that if you are going to taper for two weeks and you usually train eight miles per day, you are better off getting your daily mileage down to 4-5 miles very quickly rather than through a gradual process. This is because the quicker reduction seems to spur more rapid recovery from and response to the previous training; slower reductions are much more like routine training loads and are less like tapers. Once you have got your mileage down to 4-5 quickly, you can then ease off on the slashing, slowly descending to just two miles-or-so of training per day just before competition.
Banister offers one final suggestion: make sure your tapering periods include at least one day off per week, with no exercise at all. These days off enhance fitness and reduce fatigue in his complex mathematical models. And the same is true in real life!

Owen Anderson

References

1. International Journal of Sports Medicine, vol 15, pp 492-497, 1994

2. Journal of Applied Physiology, vol 72, pp 706-711, 1992

3. International Journal of Sports Medicine, vol 11, pp 41-45, 1990

4. Medicine and Science in Sports and Exercise, vol 26, pp 624-631, 1994

5. Physician and Sportsmedicine, vol. 13, pp 94-100, 1985

6. Medicine and Science in Sports and Exercise, vol 21(2), pS23, 1989

7. Medicine and Science in Sports and Exercise, vol. 22(2), Supplement, #801, 1990

8. Medicine and Science in Sports and Exercise, vol 26(5), pp624-631, 1994

9. European Journal of Applied Physiology, vol 79, pp 182-191, 1999

10. Journal Therm Bid, vol 18, pp 587-597, 1993

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