Sports Performance Bulletin looks at more new research on training intensity distribution; what works for the pros may not in be ideal for amateur and recreational athletes MORE
Tapering training to improve athlete’s endurance
Owen Anderson explains what exactly happens inside your body when you taper – and why you should do it more often
Most endurance athletes recognize that tapering before competitions is a good idea, but few understand exactly why tapering has such a positive effect on performance.
Physiologists first became aware of the benefits of tapering in the 1970’s, but at that time there was little understanding of what was going on inside athletes’ bodies as they tapered. One of the first investigations to take a close look at the physiological alterations associated with tapering was carried out by renowned exercise scientist David Costill at Ball State University in the mid-1980’s.
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, but it was not clear what had actually caused the upgrade in LT.
Did the swimmers’ muscles have more time (during the tapering period) to create mitochondria and MCT1s (carrier molecules which transport lactate into muscle cells), so that more lactate could be cleared from the blood and broken down for energy? Or had the swimmers somehow gotten stronger, perhaps because their muscles had more energy and substrate available for protein synthesis once training was reduced? Gains in functional strength usually improve lactate threshold, because as muscle cells get stronger fewer of them need to be activated to swim (or run) at a particular pace, which in turn produces a lower lactate output (there are simply fewer cells pushing lactate through their membranes into the ‘outside world’).
Indeed, the swimmers’ arm strength advanced by about 25 per cent during the tapering period, suggesting that gains in strength played a important role in advancing performance (and lactate threshold). Still, researchers were left with two crucial questions: was strength really the key variable which responded to tapering – or just one of several major players? And if heightened strength happened to be the vital outcome of a tapering period, how long should a taper be in order to optimize strength advancements?
Fortunately, those questions have gradually been answered since then, with some of the fog surrounding the tapering process being cleared by a group of Canadian researchers in the late 1980s. The Canadian team, 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 did something absolutely crazy: they ran only six miles during the week, with almost all of the running consisting of red-hot 500-metre intervals on the track.
After this very interesting 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. The effects of tapering and detraining were fighting each other to a standstill.
And the winners?
Amazingly, 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 in fine fettle. 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.
Truthfully, effect no. 1 – greater glycogen storage – should be a tapering bonus only for athletes who have been doing a poor job of taking in carbohydrate during their regular training. If you are training heavily but eating inadequate amounts of carbohydrate, your muscle-glycogen concentrations will be abnormally low as you train but will increase rather dramatically whenever you cut back on training (i. e., whenever you taper), because the reduced training will place a lighter demand on muscle-glycogen breakdown. That will make it seem as though one of the key benefits of tapering is a heightened muscle-glycogen concentration.
However, the important point to remember is that you can’t train well if your muscle-glycogen levels are sub-par, so you should never wait for a tapering period to set them right. It’s advisable to take in four grams of carbohydrate per pound of body weight per day during strenuous training to keep muscle glycogen ample and training intensity high. By doing so, you’ll skirt the need to wait for a tapering period to lower carbohydrate breakdown – and thus boost muscle-glycogen levels. Peak Performance suspects that the Canadian runners’ carbohydrate intake rates were sub-optimal during their 50-mile weeks, which would have created significantly depleted muscle-glycogen stores. The six-mile per week runners, breaking down much less carbohydrate during the taper week than the 18-mile runners, were naturally able to pack more carbohydrate back into their muscles. However, if both groups had entered the tapering week with full glycogen stores, the difference would probably not have been present.
Does tapering excite the kidneys?
The simultaneous occurrence of the second and third effects (noted above) is a little confusing. Usually red-cell concentrations increase when blood plasma decreases, and decrease as plasma advances; the two don’t often march upward together, as they did for the six-mile runners. These congruent phenomena suggest that a ‘crazy-cutback’ taper can produce a ‘kidney effect’ on performance. Perhaps when training is cut drastically down to an intense core the kidneys produce more EPO to spike red-cell density and exhort hormones which help retain blood plasma to swing into action (the kidneys do play a very strong role in regulating blood plasma).
Other studies definitely indicate that plasma upswings tend to be more associated with high-intensity training rather than easy work, which is probably why the six-mile per week, intensely interval-trained runners fared better with their plasma than the slovenly 18-mile per week characters. More plasma can help performance by giving the blood a chance to satisfy the twin demands made on it during strenuous exercise – greater flow to the skin to promote cooling and of course enhanced movement to the muscles to provide oxygen and energy. Thus, the Canadian research teaches us that training volume should come down (and intensity should go up) so that blood volume can climb.
Effect no. 4 – enhanced enzyme activity – is no surprise at all. With the 88-per cent reduction in training, the muscle cells of the six-mile per week runners had time on their hands – and the energy and materials needed to synthesize aerobic enzymes with zeal and passion. The hard running carried out to complete that meagre total of six miles may have helped to give those enzymes an additional boost. We suspect that enzyme boosting was a factor for Costill’s swimmers, too, although Dave didn’t actually measure enzyme levels. Overall, the lesson from Costill and McMaster is that if you keep your tapers short on volume, you’ll get enzyme lifting, lactate upgrading, and muscle strengthening. If you make your tapers short and hard, you’ll probably get those same things (although lactate and strength weren’t actually measured by the McMaster whitecoats), and you’ll also enjoy lots more blood sloshing around in your arteries and veins, which will keep you cooler when you exercise and also bring lots of nice things to your muscle fibres.
Tapering is a neural thing
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’ (sounds familiar, doesn’t it?). 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. That shouldn’t have been a big surprise, since the chief East Carolina researcher, Joe Houmard, did his graduate work in Costill’s Ball-State laboratory. 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. Thus, 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. Normally, we would expect improvements in running economy to be a direct result of an enhanced intrinsic ability of muscle cells to create propulsive force. As we mentioned earlier, as individual muscle cells get stronger, fewer of them are needed to maintain a particular pace, and thus the ‘cost’ of running drops, i.e., economy improves.
However, that cannot be the explanation for the economy improvement made by the run-tapered East-Carolina runners, since any upswing in muscular force production which they achieved should have been matched by the bike-tapered athletes. You can’t argue that the hard running during the tapering week made the run-tapered athletes’ muscle cells stronger, because muscles require more than a week to add on enough new contractile proteins to create greater force production.
Rather, the hard running during the taper week probably produced a neural change – an improved ability of a better-rested nervous system to control and coordinate better-rested muscles at decent running speeds. That neural change could not occur in the bike-tapered group, since those athletes were working on biking rather than running coordination. Remember that when we are thinking about neural training we can cast aside the traditional adage that it takes at least 10 days for any high-quality training session to actually produce higher fitness. Improvements in neural function can occur in a matter of minutes, as any athlete who has tried out balance-board training – and gotten better at balancing over the course of a single workout – can attest.
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.
Meanwhile in South Carolina
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 ‘slumped’ to 22 miles (a 60-per cent diminution). 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 (the running velocity which produces the highest rate of oxygen utilization) 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. PP believes that you would get this effect with almost any kind of taper which cuts training volume significantly.
Here are our summary points and conclusions concerning tapering:
1. Unless you’re a very high-volume trainer (i. e., unless you run more than 60 miles per week if you are a runner), you can taper for just one week prior to any competitions lasting less than an hour. During that week, cut total mileage by about 65 per cent, and divide what’s left 50-50 between hard effort and soft work. If you’re a high-mileage athlete, use the same strategy, but give yourself at least 10 days of cutback, with two weeks being even better. 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 (if your carb intake has been less than optimal). 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.
2. If you’re a high-volume endurance athlete, your functional strength is moderate or poor, you experience a fair amount of soreness and stiffness during your training, and your competitive event lasts longer than an hour, taper for three to four weeks before your major competition, gradually cutting back on your mileage (volume) during that time and letting quality work steadily comprise a higher fraction of the distance which remains.
3. If you’re a functionally strong athlete who carries out PP’s recommended strength-training routines, you can probably get by with two to three weeks of tapering before a competition lasting longer than an hour. During those two to three weeks, the tapering strategy is the same: volume falls down while hard exertion’s piece of the pie steadily advances.
4. You should taper 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 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.