Monday, March 26, 2007

More on Tapering

I was reading up on tapering and the research behind exactly how much to cut back and what to do this last week and found some interesting stuff that I thought you would enjoy reading. I realize how mentally challenging it is for endurance athletes to do less right before their big race so I wanted to find some evidence to help and I did...

Study #1- One of the first investigations to take a close look at the physiological alterations associated with tapering was carried out by exercise scientist David Costill at Ball State University in the mid-1980s.

The collegiate swimmers Costill was studying tapered by reducing daily swimming distance by 67 per cent for 15 days. The taper was a success - performance times improved by almost 4 per cent. Physiologically, the tapered swimmers had lower blood-lactate levels during fast swimming, a sign that lactate threshold (LT) had improved.

Another Study- A group of Canadian researchers in the 1980s, carrying out their research at McMaster University in Ontario, divided well-conditioned runners who averaged about 50 miles of running per week into three groups. One group just 'hung out' for one week, doing no running at all. A second group jogged easily for a total of 18 miles over the course of a week (note that this was approximately a 64-per cent cutback in their training, about the same that Costill had utilized with his swimmers). The third group ran only six miles during the week, with almost all of the running consisting of 500-metre intervals on the track.

After this week, the runners who had logged 18 easy miles improved their performances by about 6 per cent (note how close this is to the 4-per cent gain achieved by Costill's swimmers, who used the similar strategy of continuing to train every day but with a greatly reduced distance of training). Meanwhile, the 'nothing' group - the runners who carried out no running at all - improved by not a single second or even a fraction of a metre. Most likely, any benefits they were getting from resting were offset by the slow-but-steady losses in fitness which were occurring due to their complete lack of physical activity.

And the winners? The runners who ran just six miles during the week were in the best shape of all, even though they had cut training volume by 88 per cent. Their performances shot up by 22 per cent, compared to the 6- and 0-per cent gains achieved by the other two groups, and physiologically the six-mile runners were doing great. Although important things like running economy, lactate threshold, and VO2max weren't measured, the 6-mile people enjoyed four key advantages over the other competitors:

1. They had more glycogen in their leg muscles.
2. Their density of red blood cells was greater.
3. They actually had more blood plasma than the other two groups.
4. Enzyme activity in their leg muscles was greater.

Study #3- In the early 1990s, researchers at East Carolina University and the University of South Carolina carried out unique investigations which suggested that a significant portion of the improvement associated with tapering is a 'neural thing'. Specifically, investigators at East Carolina University took a group of eight experienced runners who had been running about 43 miles per week and cut their training to 6.5 miles of hard intervals (at 5-K pace or faster) and seven miles of jogging for one week (that added up to 13.5 miles of total running). Overall, training volume was trimmed by 69 per cent, very close to the cut undertaken by Costill's swimmers eight or nine years earlier. In this East-Carolina study, a second group of eight runners utilized a similar one-week tapering scheme, but all of their workouts were carried out on exercise bicycles. Although the subjects in this second group were cycling, not running, their heart rates, interval durations, and total numbers of intervals were exactly the same, compared with the group which ran during the tapering period. This represented highly ingenious methodology, because the high intensities and low training volumes utilized by the bike-tapered athletes should have produced the same effects on blood-plasma volume and enzyme activities as was the case for the run-tapered individuals, who used the same intensities and volumes.

This research represented a reasonable way to uncover the specific effects of carrying out one's exact sporting activity at a high intensity during a tapering period, rather than just exercising strenuously. Yet a third 'control' group of eight runners blithely continued to train in their usual way during the experimental week, logging about 43 total miles and carrying out their customary amount of quality training.

Run tapering is best. When a 5-K race was held on the eighth day of the study, the run-tapered athletes improved their 5-K times by an average of 30 seconds, while the bike-tapered and control runners failed to get better at all. Amazingly, all eight of the run-tapered individuals improved their 5-K clockings!Most interestingly, running economy improved by 6 per cent for the run-tapered subjects but didn't budge in a positive direction at all for the bike-tapered or control runners.

The lesson from the East Carolina research is that a tapering period should be planned so as to permit improved neuromuscular coordination - and thus efficiency of movement. That means matching a large part of the limited exercise one does undertake during the tapering period to the high intensity associated with the upcoming competition.

Another Observation- In the South Carolina research mentioned earlier, there were two groups of runners. Members of one group covered their usual 55 miles of running over the course of a week, while the second-group's runners dropped to 22 miles (a 60-per cent decrease). This second group placed a very large emphasis on high-intensity intervals during the taper week.

In this study, the tapered runners improved economy by 6 per cent - the same gain achieved by the East Carolina harriers (that's not bad for one week!). Most critically, vVO2max also rose, an advance we can link to the heightened neuromuscular coordination and enhanced economy produced by the fast interval running, in concert with the easier overall load. As coordination and efficiency at high speed improve, one's previous vVO2max is no longer vVO2max, because the oxygen cost of running at that speed has fallen. Thus, one reaches VO2max at a higher speed, i. e., with a loftier vVO2max (vVO2max is one of the very best predictors of endurance performance).

Finally, we shouldn't fail to mention research recently published in Medicine and Science in Sports and Exercise, which revealed that a two-week, performance-enhancing taper carried out by highly competitive swimmers prior to a national championship produced three key changes - increased levels of blood-plasma norepinephrine, higher heart rates during maximal swimming, and an overall 'reduction in (mental) confusion.'

The norepinephrine change is an interesting result which hasn't been documented (or looked for) in previous research. Basically, norepinephrine is a neurotransmitter and hormone which can increase heart rate, spike force production by muscles, and enhance mental awareness. Hard training tends to drive norepinephrine levels down, and easier training brings them back up, so it's not surprising that the taper helped epinephrine climb, or that the epinephrine was associated with higher performance, given its basic effects.

Certainly, the epinephrine may have been partially behind the higher heart rates observed during maximal swimming. Bear in mind that higher heart rates are not a bad thing. The heart itself tends to respond to the muscles; as the muscles upgrade their ability to work intensely, the heart will 'follow' with higher rates of beating to keep the muscles well supplied with oxygen and fuel. This doesn't mean that the work is 'harder' for the athlete but simply reflects the fact that the athlete has moved up to a higher plateau of neuromuscular performance.

The surge in norepinephrine may also have been partially responsible for removing the cloud of 'confusion' which seemed to hang over the swimmers' heads. Basically, heavy training tends to produce fair amounts of mental lethargy, anxiety, confusion, and depression, and tapering helps to clear the mind, partly by changing the concentrations of neurotransmitters such as norepinephrine.

And finally my summary:
For Olympic distance and sprint distance races, taper for at least one week prior. During that week, cut total mileage by about 65 per cent, and divide what's left 50-50 between hard effort and soft work.

For half Ironman, use the same strategy, but give yourself at least 10 days of cutback, with two weeks being even better.

And for an Ironman taper for at least 3-4 weeks cutting back gradually on your volume during that time and letting quality work steadily comprise a higher fraction of the distance which remains.

Remember that turning down the volume knob on your training helps with your enzymes and hormones and may give your muscles a chance to build more proteins and store more glycogen. Utilizing the high-intensity work during the taper boosts your blood-volume and also works on the neuromuscular aspects of performance which are so critical for reaching your highest plateau of fitness.

You should taper or have a recovery week, not just before your big races but on a monthly basis. After all, since tapering is such a great thing, why reserve it for just a couple of times a year? If you taper(or recover) for the last five to seven days of each month, you'll find that your fitness will move upward in sizable jumps, instead of just creeping up a little or - worse yet - stagnating at the same level.

Happy Taper!