Altitude training for high level cycling

Resume Altitude training for high level cycling

Cycling includes a wide range of disciplines from Bicycle Moto Cross (BMX), Trials, Down-Hill or Four Cross (4X) to Mountain Bike, Track or Road. The first group is supposed to be more “acidotic” as the time spent in competition goes from approximately 40 seconds to 4 minutes in different length maximal effort intervals, while the second group mainly uses aerobic metabolism (except the shorter competitions of track cycling that could be in the first group). By the way, in different grade, aerobic capacity is very important also for the first group as recovery between these high intensity efforts during a competition is of great importance (Zabala et al., in press). Typically, endurance cyclists have been using hypoxia as a training method, especially when competitions take part in high mountains as Pyrenees, Dolomites or ski stations in the case of mountain bike, but nowadays there are much more cyclists of the shorter durations that include hypoxic training in their plans. This use has been mainly related to the acceleration of Erythropoietic response (Robach et al., 2006), although it has been demonstrated that there is a multifactor cascade of responses induced by hypoxia to produce physiological changes and gains in performance (Gore et al., 2007). The purposes of cyclists when using hypoxia are 1) acclimatization, and 2) gain of performance at sea level (also, but less important, 3) to improve their recovery quality sleeping at low to moderate altitudes): 1) The effects of short-term acclimatization to altitude are different for aerobic or anaerobic exercise performance, as suggested i.e. by Burtscher et al. (2006) showing that at an altitude of 3200 m anaerobic cycling performance was not affected for a 30 s maximal effort, while aerobic performance was reduced by 12% and 11.3% for efforts of 5 and 50 min respectively. This gives us the idea of how important can be for Down-Hill the aerobic capacity if competition lasts 3 to 4 min. And once a short-term acclimatization is done (i.e. 3 days) the decrease in performance can recover 50% of the initial loss of a 50 min cycling. 2) Gains in cycling performance vary between individuals, but could really be close to a 1% as an average (Hahn and Gore, 2001). This can be seen as a poor gain, but this is not nonsense when at Olympic level often the differences in performance are typically less than 0.5% (Wilber, 2007). Living and training at moderate altitude of approximately 2500 m but training near sea level are popular practices among elite cyclists that pretend to improve performance at sea level (Hahn and Gore, 2001). Sleeping in moderate hypoxia (2650-3300 m) for up to 23 days may offer practical benefit to elite athletes, but that any effect is not likely due to increased Haemoglobin mass or maximum oxygen uptake (Hahn et al., 2001). In any case, it is not generally recommended to train hard physically in altitudes higher than 3000 m (Brugniaux et al., 2006). Mountain bikers many times compete at 2000-3000 m altitude where peak oxygen consumption declines approximately 10-20% (Clark et al., 2007). Cyclists that compete the same day of the competition without doing acclimatization sometimes although they are not significantly affected physiologically or in coordination patterns (Mornieux et al., 2007), they tend to mis-pace their effort if it is the first time they perform (Clark et al., 2007) -and this is something we find when Junior cyclists compete for the first time at altitude. The models used by cyclist in the past decades have gone from Live Low-Train High (LLTH), Live High-Train High (LHTH), and Live High-Train Low (LHTL). The most recognized and used supported in scientific basis is the LHTL model, although it has been famous the way Lance Armstrong used to train in Teide Volcano (Spain). The popular LHTL method (Levine and Stray-Gundersen, 1997) depends on 1) living high enough, for enough hours per day, for a long enough period of time, and 2) training low enough to allow maximal quality of high intensity workouts requiring high rates of sustained oxidative flux (Levine and Stray-Gundersen, 2006). It is recommended for LHTL 2000-2500 m of natural elevation for at list 4 weeks and 22 hours a day (Wilber et al., 2007). It is argued that LLTH model can weakened the antioxidant capacities of the athletes (Pialoux et al., 2006). LHTH is suggested not to improve sea level performance of high level athletes. Hypoxic training can be mainly administered by means of 1) Continuous Hypoxic Training (CHT) or 2) Intermittent Hypoxic Training (IHT). CHT is commonly used at a moderate altitude to 2000-3000 m permitting active training, while IHT can be around 3000-6500 m or more and is generally administered in passive manner. The first is used continuously in stages in altitude or daily for sleeping at night, and the second is administered from 60-90 min, 6-10 intervals of 5 min hypoxia and 5 min rest, around 5 sessions/week during at list 7 subsequent days for acclimatization (Foster et al., 2005), or at list 5-6 weeks -Truijens et al. (2007) or Rodríguez et al. (2007) did not find improvements after 4 weeks- for gaining performance at sea level (Hamlin and Hellemans, 2007). An example is the study carried out by Dufour et al. (2006) that achieved a significant improvement in aerobic performance capacity after 6 weeks of IHT combined twice a week with 2 sessions at second ventilatory threshold during 24-40 min, as well as an improvement in mitochondrial properties in skeletal muscle (Ponsot et al., 2007). Also, IHT can be provided at rest to stimulate acclimatization, or during exercise to enhance training stimulus (Levine, 2002). However, Koehle et al. (2007, 2008) suggest that there is no difference in the results obtained by 60 min of continuous IHT or by twelve 5 min bouts of IHT separated by 5 min bouts of room air. Genetics play an important role and many coaches or scientists talk about “responder” and “non responder” athletes. The oxygen sensitive subunit Alfa of Hypoxia Inducible Factor (HIF-1) complex is an essential protein for oxygen homeostasis system for cell energy production and survival, and the primary transcriptional response factor for acclimation to hypoxic stress (Mason et al., 2007; Pisani and Dechesne, 2005). So the loss of HIF-1 alfa can result in altered exercise endurance (Mason et al., 2007; Mason et al., 2004). It is said that the lack of HIF-1 protein could be the reason why a great and successful French cyclist failed in consequent participations in the famous stages across higher mountains of the “Tour of France”. It is suggested that multiple short duration bouts of intermittent hypoxia provoke larger changes in chemosensivity than longer duration bouts of intermittent hypoxia (Koehle et al., 2008). It has been also hypothesized that oxygen homeostasis regulation system depends on muscle fibre type (Pisani and Dechesne, 2005). The use of ergogenic aids as Sodium Bicarbonate could minimise the effect of acidosis by empowering the buffer capacity related i.e. to the increase of lactate which is now supposed to delay acidosis as well as act as a nutrient. This is the case observed in BMX series (Zabala et al., in press). Also, sildenafil (Viagra®) is suggested to protect against the development of altitude-induced pulmonary hypertension (Ricart et al. 2005) improving gas exchange, limiting the altitude-induced hypoxemia and decreasing in exercise performance (Faoro et al., 2007; Richalet et al., 2005). It has been also reported that sildenafil can greatly improve cerebral oxygenation at altitude (Chan et al., 2005), cardiovascular function and performance in acute hypoxia but not in normoxia (Hsu et al., 2006). IHT seems to benefit the acclimatization in the first days of moderate altitude, and we have used hypoxic tents in moderate altitude with success. Hypoxic training must be included in the training program and it has to be individualized, taking into account its effect as special stimulus. At the same time, specific ergogenic aids should be used as well as overtraining markers are controlled by means of blood analyses and other practical indexes as Rating of Perceived Exertion (RPE), Heart Rate variability, resting Heart Rate, sleeping pattern, and also haematological-biochemical information or pulseoximeter use. Natural and artificial methods of hypoxia can be combined, although artificial moderate exposure improves preaclimatization and can be the first step. The evolution, if possible, could be IHT, natural moderate exposure, and sleeping regularly in a tent. By the way, more important than the method is the quantity and quality of the stimulus used, so we should be very patient and step by step slowly if we have time and this training has been well planed for the season. The quantity and quality of the work will also depend on the moment of the season, the time we have for this work and the objective pretended (this could suggest one or another method). By the way, chronic adaptations may occur after years of well planned hypoxic exposure combining natural and artificial stimulus. The key point will be the general effect of training in each athlete, taking into account all the stimulus used, one of them hypoxia. The variability among subjects is great (Levine and Stray-Gundersen, 2006). At the end the last step must be sport success by improving athletes’ performance, and we can say i.e. that Spanish Mountain Bike team has been one of the most successful teams competing in altitude, reaching 5 world championships (team and individual) in the 3 occasions we have competed at moderate altitude, because of working seriously for these specific contexts of competition -Sierra Nevada 2000 (Spain), Colorado 2001 (USA) or Livigno 2005 (Italy).

References

Real Federación Española de Ciclismo