How does sleep loss really affect athletes and what steps can they take to minimize its impact? Andrew Sheaff looks at brand new research MORE
Tapering and performance
In order to be the best in whatever swimming discipline, competitive athletes and their coaches are constantly seeking new and effective methods to improve performance.
Swim suit design, goggle design, shaving down and warming-up techniques are all currently used, but the most important element is the training itself and the factors affecting it, particularly in the few days before competition. A common practice used by swimmers and coaches is the well-established technique of tapering, whereby the training volume of a swimmer is drastically reduced 7-21 days pre-competition (Costill, 1985, Johns et al, 1992). This tapering is associated with many physiological alterations that have a positive impact on swimming performance, and these will be closely looked at in this review.
Components of tapering
Tapering can be controlled through three variables, (a) frequency of sessions per week, (b) intensity of each session, and (c) the duration of the taper in general. Costill et al (1985;1991) studied various taper schedules and found that these three variables provided some insight into actual performance improvement.
The first common characteristic with tapering is that training is reduced in an INCREMENTAL fashion as opposed to a general training reduction (eg, 15,000m per week to 10,000m). Tapering has become the preferred method of the two because, as Costill et al (1991) and Johns et al (1992) demonstrated, muscular power is enhanced and performance improved significantly after 10-21 days taper with competitive swimmers. Houmard et al (1990) demonstrated (with runners) that with a reduction in training volume to 70 per cent of normal, 5K race performance or muscular power were not improved. Research thus favours tapered training.
A successful taper should also incorporate a drastic reduction in volume. Tapers that improve swimming performance have been found to consist of 60-90 per cent reduction in weekly training volume (Costill et al, 1985, 1991). These positive effects are thought to be primarily mediated by a recoveryphenomenon from previous days or weeks of intense training (Houmard, 1991). This recuperation can only occur if training volume is drastically reduced. In distance runners, it was found that a seven-day, 62 per cent reduction in weekly training volume did not improve performance, determined by an exercise time to exhaustion test (Sheply et al, 1992). In contrast, a 90 per cent reduction in weekly training volume over seven days resulted in a 22 per cent extension in time to exhaustion. It therefore appears that a huge reduction in weekly training is required in order to recover and allow the rebound effect to occur.
With regard to the type of training while tapering, it commonly takes the form of interval work, with sufficient recovery in order to maximize exercise intensity (Costill et al, 1991; Johns et al, 1992). Training at an intensity of 70% VO2max either maintained or actually worsened performance (McConnell at al, 1993). In contrast, tapers involving training at 90% VO2max improved performance (Costill et al, 1985,1991). The reasons behind this were put forward by Houmard (1991) who said that intense exercise may be necessary to maintain training-associated adaptations with the reduction in training volume during the tapering period. Intense interval work, when coupled with a reduction in training volume, may also provide a unique stimulus to the musculoskeletal system which results in adaptations conducive to improving performance.
Exercise frequency is concerned with the number of sessions performed each week (Houmard and Johns, 1994). The reduction in training volume cannot be achieved at the expense of a drastic reduction in frequency. Neufer at al ( 1987) examined the effects of swim-reduced training on swimming power and blood-lactate production after submaximal exercise. Two regimes were examined: (1) 80 per cent reduction in training volume, 50 per cent in frequency, and (2) 95 per cent reduction in volume and 85 per cent in training frequency. Results of the study found that swimming power significantly decreased after only seven days and submaximal blood lactate levels increased after 28 days of either reduced-training regime. These changes were indicative of a loss of training-associated adaptations and, most likely, a decrement in performance. The reduction in training schedules here were quite dramatic. Studies in which performance-related variables were maintained or improved incorporated only a 20-50 per cent reduction (Costill et al, 1985; Sheply et al, 1992). Heart rate changes have also been reported by Houmard et al (1989), who found an increase during submaximal exercise in distance runners after a 10-day, 50 per cent reduction in training frequency. It can therefore be concluded that weekly training frequency should be reduced by no more than 50 per cent during taper. Houmard (1991) actually suggests a reduction of no more than 20 per cent. During periods of optimal performance, swimmers often refer to having ‘a good feel of the water’. It is this ‘feel’ that is lost or reduced with too dramatic a reduction in training frequency, and for that reason I would support Houmard’s suggestion of no more than 20 per cent reduction in frequency.
How long should a taper programme last? Yamamoto et al (1988) compared the effects of either a 45-day or a 15-day taper on blood haematocrit and haemoglobin in national class swimmers. They observed that peak performance values were obtained seven days into the taper, and that this would be the optimum taper duration, with anything longer resulting in performance loss. Unfortunately, though, this study didn’t measure actual swimming performance. Studies that did involve performance assessment with tapering have reported improvements with tapers lasting from 7-21 days (Costill et al, 1985, 1991; Houmard et al, 1994; Johns et al 1992). However, the effects of a more prolonged taper have not yet been thoroughly investigated, Houmard et al (1992) suggest a taper lasting 21 days would only maintain, rather than improve, actual performance.
The physiological effects of taper
Maximal Oxygen Consumption (VO2max)
This well-established method has proven to be very reliable in assessing cardiorespiratory fitness levels. It is the maximum amount of oxygen utilised during incremental exercise to exhaustion.It is more commonly produced through treadmill or cycle ergometry but it can be used by swimmers in the actual pool. This is achieved by either tethered swimming where the resistance is incrementally increased, or a free swim at maximal speed with oxygen consumption calculated from expired gases obtained 20-40 seconds post-exercise (Neufer at al, 1987). With swimming training, VO2max increases quite significantly by some 14-25 per cent (Kieres & Plowman, 1991). However, VO2max was unchanged with a 21-day taper in nine elite swimmers (Van Handel et al, 1988). Other studies have reported improved performance with taper with VO2max remaining unchanged. (Houmard et al, 1994). Alterations in performance which are independent of VO2max must therefore be associated with muscular adaptations rather than the oxygen delivery (Sheply et al, 1992). This could be the case with tapering, as muscular power in swimmers has been reported to improve while tapering.
Variables commonly used as indices of submaximal exercise efficiency in swimmers include oxygen uptake, heart rate, blood lactate and stroke distance. Costill et al (1991) reported no differences in post-exercise blood balance (lactate, pH and bicarbonate), and heart rate with a 14-day taper. Also, Van Handel et al (1988) reported no significant differences in post-exercise lactate profiles with a 20-day taper. Johns et al (1992) finally reported no alterations in VO2max, post-lactate levels and stroke distance with either a 10-day or 14-day taper. In contrast to these stroke-distance findings, Costill et al (1991) reported increases with a taper programme. However, swimmers commonly remove body hair (shave down) before competitions and during taper in order to minimise resistance. Johns et al (1992) actually reported increases in stroke distance as a result of shaving down after 10 days tapering (with no improvements in the other variables).
A restoration of haemoglobin/haematocrit prior to competition is desirable, as it may enhance actual oxygen-carrying capacity and thus per-formance. Yamamoto et al (1988) reported peak haemoglobin levels after seven days taper. Similar results have also been reported by means of differing tapers (Burke et al, 1982). Elevations in these variables may be associated with a decrease in exercise-induced haemolysis from a reduction in training volume (Houmard et al, 1991). Plasma creatine kinase (CK) level is hypothesized to be positively related to a degree of muscular cellular damage (Noakes, 1985), but quality research is still required to demonstrate this.
Muscle biopsy studies in runners and cyclists have demonstrated a consistent elevation in muscle glycogen (15-35 per cent) with tapering. To date there have been no studies on the effects on competitive swimmers when tapering. The finding, though, is important, in that the benefits which could be achieved due to the greater availability of energy substrate are vast, since its positive links with endurance performance are commonly accepted (Costill et al, 1991). Sheply et al (1992) also reported increases in oxidative enzymes with taper, providing a huge benefit to endurance performance. It is likely that similar adaptations with taper would occur in swimmers, but nothing has been directly documented.
Costill et al (1991) reported significant improve-ments in dry-land (swim bench) and tethered-swimming power with a 14-day taper. Johns et al (1992) also found gains in tethered-swimming power with a 10- and 14-day taper. As a result of endurance training, muscular power is decreased because of the residual fatigue or inhibition of neural or intrinsic muscle properties (Dudley & Djamil, 1985). Because of the training elite swimmers undergo (3-4 hours per day, 10,000m per day), muscular power would be expected to reduce. It would appear, though, that sufficient tapering allows restoration of power while maintaining the endurance-related metabolic benefits gained (Houmard & Johns, 1994). The actual ability to exert power is highly related to swimming performance (Costill et al, 1983). It is therefore concluded that the improvement in power with taper is probably the major factor responsible for the improvement in competitive swimming performance (Houmard & Johns, (1994).
What about actual swim performance?
Consistent research suggests that an improvement of 3 per cent in swimming performance can be achieved as a result of tapering. Costill et al (1985) compared swim performance during normal training and with a 14-day taper. Swimming performance in all strokes improved by an average of 3.1 per cent with tapering. Similar results were reported again by Costill et al (1990), who assessed performance after two tapers in the same competitive season. Johns et al (1992) also demonstrated a 3 per cent improvement after a 10- and 14-day taper programme in swimmers over a variety of distances and strokes. And we mustn’t forget the shaving down carried out by swimmers, which could also have affected performances (Sharp et al, 1988).
In order to produce the best possible results from tapering, both coaches and swimmers need to be aware of the following factors:
2 The individuality of the taper process (this is an ABSOLUTELY VITAL consideration). Every athlete will respond to taper differently, so communication between coach and swimmer is of the utmost importance.
3 Mini-tapers and retapers (throughout the season for more than one competition).
4 Shaving and mental preparation.
5 Realistic estimation of performance goals.
When planning any form of tapering programme I would recommend the following points. The training incorporated into the programme should be reduced in an incremental fashion with a 60-90 per cent reduction in training volume. Training intensities should take the form of high interval work (90% VO2max) with sufficient rest between sets. The frequency of training should be reduced by no more than 20 per cent in order for the swimmers to maintain their ‘feel’ of the water, and, finally, duration of the taper programme should be decided on an individual basis (because of varying responses to tapers) and last between seven and 21 days.