06 May 2014

Tapering in mountain ultramarathon running

The mountain ultramarathon race season is now certainly here, both with big races like the upcoming Transvulcania this weekend, but also with an increasing number of local races when more and more of the winter snow is disappearing. I have still not decided if, and when, to race before this year’s main event for me, Petite Trotte à Léon, in the end of August. One thing that makes me hesitate is the disruption in my training that preparation before and recovery after the race will cause. I could of course just run a race like a longer training run, but that would most likely be too stressful and lead to even longer need for recovery, so some kind of tapering before the race would most likely be needed. I just came across an interesting blog post about tapering written in Swedish by Johan Renström. It is written from a personal perspective and not focused on ultramarathon running specifically, but it inspired me to look at what is known about tapering for endurance running. First, there are different definitions of what tapering is, but the scientific definition appears to be “a progressive nonlinear reduction of the training load during a variable period of time in an attempt to reduce the physiological and psychological stress of daily training and optimize sports performance” (Mujika & Padilla “Scientific basis for precompetition tapering strategies” Med Sci Sport Exerc 2003; 35: 1182-1187).

In his blog post, Renström refers to the probably best quoted study about tapering in recent years which is a metaanalysis of the effects of tapering on athletic performance by Bosquet and colleagues (Bosquet et al “Effects of tapering on performance: A meta-analysis” Med Sci Sports Exerc 2007; 39: 1358-1365). In this metaanalysis 27 out of 182 potential studies of tapering on competitive athletes were included and there was for instance eight studies of swimmers (number of athletes [N] = 249), six studies of cyclists (N = 80) and nine studies on runners (N = 110). The overall results show a maximal, albeit still small to moderate, gain of a tapering intervention of 2-weeks duration where the training volume is exponentially decreased by 41-60%, without any modification of either training intensity or frequency (see Figure below). The mean improvement was 1.96%, clearly of relevance for competitive athletes as such an improvement in for instance Olympic swimming or track and field running is larger than the difference between the gold medalist and fourth place in general.

The effect of tapering (From Bosquet et al 2007)
The strength of this meta-analysis is the amount of data included. However, this is also the weakness as my main critique of the study that it is difficult to draw conclusions regarding tapering for a specific sport based on data from a lot of very different sports. In my teens I competed rather seriously in military pentathlon, a sport containing heavy elements of both swimming and running, and my own personal experience is that tapering for swimming is clearly different than for running. The authors also clearly state this in the paper and discuss the differences between sports, but in the interpretation of the study afterwards the general findings are those that are applied whatever sport. There are clear differences between swimming, running and cycling (see Figure below), and although the numbers are too small to draw conclusions with certainty, it appears that for running the optimal taper duration appear to be 8-14 days and that the optimal decrease in training volume is somewhere between 21-60%.
 
The effect of tapering in different sports (From Bosquet et al 2007)
The studies included are all focused on short running performances and it is unclear whether the results could be applied to longer ultramarathon distances and whether for instance longer tapering would be more beneficial for longer distances. However, results from a large new review from the same authors involving training cessation shows measurable negative effects on muscular performance already after 15 to 28 days (Bosquet et al “Effect of training cessation on muscular performance: A meta-analysis” Scand J Med Sci Sport 2013; 23: 140-149). The data with regards to mid-distance running is somewhat conflicting both with regards to duration as some studies indicate that training can be reduced for as much as 15 weeks without loss of endurance performance (Hickson et al “Reduced training duration effects on aerobic power, endurance, and cardiac growth” J Appl Physiol 1982; 53: 225-229). With regards to volume reduction some studies indicate that low-volume tapering is better than moderate-volume (Shepley et al J “Physiological effects of tapering in highly trained athletes” Appl Physiol 1992; 53: 706-711; Mujika et al “Physiological responses to a 6-day taper in middle-distance runners: influence of training intensity and volume” Med Sci Sports Exerc 2000; 32: 511-517) and that the 21-60% found to be beneficial in Bosquet’s study would be a too small reduction. There are some studies indicating that progressive tapering (either linear or exponential [see figure below]) might be more beneficial than step (Zarkadas et al “Taper increases performance and aerobic power in triathletes” Med Sci Sports Exerc 1994; 26:34-39; Houmard et al “Reduced training maintains performance in distance runners” Int J Sports Med 1990; 11-46-52). This appears to be the case not only for aerobic capacity, but also muscle power (Brännström et al “Effects and mechanisms of tapering in maximizing muscular power” Sport Art 2013; 1: 18-23). A new computer simulation of tapering schemes indicate that increasing the training load by 20 to 30% during the final three days of the taper my even optimize performance so there is clearly a need for more research with regards to this (Thomas et al “Computer simulations assessing the potential performance benefit of a final increase in training during pre-event taper” J Strength Cond Res 2009; 23: 1729-1736).

Different types of tapering (From Mujika et al 2003)

Other limitations of the meta-analysis by Bosquet and colleagues is that in most studies included there were only men so it is unclear whether the results could be applied directly also to women. The physiology and metabolism between men and women has in several studies been shown to be different. The effect of age is also unclear, as is the athletes training status before the taper, whether they were overtrained/overreached or not, jet-lag and pre-competition travel, altitude acclimatization, heat/cold acclimatization, hydration and nutritional status (i.e. carbohydrate loading of glycogen stores) are also possible co-founders.  The physiological and molecular effects of tapering are still unclear, even though there is starting to appear some mechanistic studies in for instance runners (Luden et al ” Myocellular basis for tapering in competitive distance runners” J Appl Physiol  2010; 108: 1501-9).

One very interesting finding in Bosquet’s meta-analysis is that the training load should not be reduced on the expense of training frequency or intensity. Several studies have found that reducing training intensity during tapering is negative and leads to a decrease in performance (reviewed in for instance Mujika et al “Physiological changes associated with the pre-event taper in athletes” Sports Med 2004; 34: 891-927 and Smith “A Framework for understanding the training process leading to elite performance” Sports Med 2003; 33: 1103-1126). It is important to retain a very high intensity of over 80-90% VO2max. One variant of a tapering scheme with volume reduction, but not training intensity is the Magness-Salazar taper, also mentioned in Renström’s blog post. In this scheme, the last week is focused on short fast intervals on hard surfaces. There are no scientific studies of the tapering scheme, but for track and field running it appears winning as it is employed by for instance Mo Farah and Galen Rupp (gold and silver medalist on 10000 meters in the 2012 Olympics in London). It is unclear whether this is relevant for mountain ultramarathon running, however, as such short training and at such high intensity might not be relevant for these distances and this kind of terrain. Personally, I tend to replace some of my volume trainings with short hard Fartlek in technical terrain, it is fun and inspiring for both the legs and the brain and I did this even before the really long Tor des Géants last year.
 
Mo Farah & Galen Rupp in London Olympics
There are almost no studies of multiple peaking during the competitive season. However, there are some recommendations found in recent reviews (Pyne et al “Peaking for optimal performance: research limitations and future directions” J Sports Sci 2009; 27: 195-202; Le Meur et al “Tapering for competition: A review” Sci & Sport 2012; 27: 77-87). They include prioritization of only 2-3 major races each season with prolonged >1 week tapering periods, with at least 2 months of training blocks between these events. For other events only short period (~4-7 days) tapers should be employed and the recovery period also kept short to allow quick restoration of the training load.

A new venue of research appears to be monitoring of the tapering through continuous analysis of the cardiac autonomic function, by following for instance post-exercise heart rate recovery (HRR) or heart rate variability (HRV) and this is possible for most athletes today through pulse watches with heart rate monitoring (reviewed in Buchheit “Monitioring training status with HR measures: do all roads lead to Rome?” Fron Physiol 2014; 5: 1-19). This is potentially very interesting and I look forward to the findings from research in this area in the coming years.

Again, there are no specific taper studies in ultramarathon athletes to my knowledge and I think the general advice to find a method that works for oneself is perhaps the best. Looking at other blog posts about tapering for ultramarathon runners, for instance by Torrence at Irunfar,  Bleakman at Ultra168 and Elson at Centurion Running, they also come to the same general conclusions.

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