An endurance athlete to compete successfully in an event of this type must have a maximum oxygen consumption (V O2max ) of at least 70 ml / kg / min, this is a minimum requirement (Hawley et al., 1997).
Athletes and coaches employ a variety of training strategies to try to increase V O2max. Recent research suggests that high intensity interval training leads to rapid improvements in V O2max and therefore one could say an improvement in performance.
Researchers at McMaster University in Canada investigated the effects of interval exercise on V O2max (MacDougall et al., 1998). The training was carried out on a cycle ergometer for three days a week. The program started with four 30-second intervals each, separated by a 4-minute rest period. During the seventh week of training the number of intervals had increased to 10, while the rest intervals were gradually reduced to two and a half minutes. V O2max increased by 9%, demonstrating that significant gains in V O2max could be achieved with relatively short duration exercise. In the first week of the program, each training session lasted 14 minutes. By week 7, the duration of each training session had increased to 30 minutes.
The team from the National Institute of Fitness and Sport in Japan found that a high intensity intermittent training program provides greater V O2max gains than a continuous training program (Tabata et al., 1997). The test was carried out with active male subjects who were divided into two groups, each of them performed a training of 5 days a week for 6 weeks. One group followed a training program that included 60 minutes of moderate intensity exercise (70% V O2max ), for a total of 5 hours per week. The V O2max in this group improved by 9%. The other group’s training sessions consisted of eight work sets, lasting 20 seconds, with 10 seconds of rest. This group worked a total of 20 minutes per week, however, their V O2max improved by 15%.
In addition to the effect on V O2max , high intensity intermittent training can improve athletic performance. Lindsay et al. (1996) reported that 4 weeks of interval training can improve performance in a 40km time trial in cyclists. The cyclists replaced approximately 15% of moderate intensity endurance training with high intensity intermittent training, completing six sessions per week for intense interval work. Each session consisted of intervals of six and eight 5-minute work sets at 80% VO2max , separated by 60 seconds of recovery. The authors found significant improvements in the time taken to do 40km in people who did the high-intensity intermittent training. It is a low volume training strategy to produce gains in aerobic power and capacity, which contradicts what is normally associated with longer training sessions. According to these studies, endurance athletes should gradually increase the intensity of intermittent training in specific preparation for competitions.
The paradox can perhaps be resolved by the findings made by Rodas et al. (2000), who reported that a high intensity intermittent training program can increase the activity of oxidative enzymes in the muscle. Rodas and his colleagues observed changes in aerobic and anaerobic metabolism in active men after a short program of intense interval training. Subjects performed high intensity intermittent workouts for two weeks consisting of two 15-second sets separated by 45 seconds of rest, followed by two 30-second sets of 100% V O2max separated by 12 minutes of rest. Every other training session, a set of extra work was added. The last 3 sessions consisted of seven 15-second sets and seven 30-second sets. The V O2max increased from 57 ± 3 to 64 ± 3 ml / min / kg and there were important increases in the activity of oxidative enzymes. These changes in the activity of oxidative enzymes can increase the rate of fat oxidation and reduce carbohydrate oxidation, consequently a reduction in the accumulation of hydrogen ions can improve performance in endurance sports (Hawley et al., 1997 ).
It is also interesting to note that an increase in training intensity can improve endurance sports performance without a change in V O2max . Acevedo and Goldfarb (1989) followed a group of trained long-distance runners who increased their training intensity to 90-95% of maximum heart rate for 8 weeks. There was an average 63-second reduction in 10km of running time and a significant decrease in plasma lactate (data not recorded), but no substantial change in V O2max (65.3 ± 2.3 vs 65.8 ± 2.4 ml.kg-1.min -1).
Although these studies provide evidence that intermittent high intensity exercise can increase V O2max and thereby improve performance in endurance sports, the different training and rest options make it difficult for an athlete or coach to design a effective training plan. A periodized training program in which intensity is taken into account from the first day of the season may be more effective than a continuous program in which intensity is worked only at the end of planning.
Hawley et al. (1997) suggested that a year-round training program should have three main phases. The first phase takes place during the non-competitive period of the athletes and consists of several months of moderate intensity, with long-duration exercises (60 minutes or more per session). Following this the athlete then enters phase two, which would involve two sessions per week of interval training. These interval work sessions can replace two of the moderate intensity workouts. Work sets during these intermittent workouts should consist of an intensity corresponding to race pace. For example, Steptoe et al. (1999) used a total of eight work sets (all performed at running pace) of 4 minutes duration with rest intervals of 90 seconds. The third phase, starting approximately 21 days before the competition, would involve high intensity intermittent training close to maximum effort. This type of training is carried out up to three times a week and can consist of up to 12 work sets lasting about 30 seconds, with rest intervals of 4 to 5 minutes (Steptoe et al., 1999).
Gaskill et al. (1999) have presented evidence of the effectiveness of this type of periodization program. In their study, cross-country skiers who had shown little improvement in competitive performance after one year of low-intensity, high-volume training had substantial gains the following year when high-intensity interval training increased and low-volume training increased. intensity in training was reduced.
In summary
The studies reviewed in this article have used intermittent high intensity exercises. However, the protocols vary widely. Some work intervals lasted 15-30 seconds, while rest periods ranged from 10 seconds to 4.5 minutes. More in-depth research is needed to establish the most effective form of interval training to determine which is appropriate or necessary to observe an improvement in V O2max .
We can be clear that the investigations are very valid to continue working with our athletes, but we have to bear in mind that each investigation is different and that it only serves the purpose for which it was created. Now it is up to each of the coaches to observe which is the scientific formula that best suits our needs and to work towards improving the performance of our athletes.
References
- Acevedo EO, Goldfarb AH (1989). Increased training intensity effects on plasma lactate, ventilatory threshold, and endurance. Medicine and Science in Sports and Exercise, 21, 563-568
- Gaskill SE, Serfass RC, Bacharach DW, Kelly JM (1999). Responses to training in cross-country skiers. Medicine and Science in Sports and Exercise, 31, 1211-1217
- Hawley JA, Myburgh KH, Noakes TD, Dennis, SC (1997). Training techniques to improve fatigue resistance and enhance endurance performance. Journal of Sports Sciences, 15, 325-333
- Lindsay FH, Hawley JA, Myburgh KH, Schomer HH, Noakes TD, Dennis SC (1996). Improved athletic performance in highly trained cyclists after interval training. Medicine and Science in Sports and Exercise, 28, 1427-1434
- MacDougall JD, Hicks AL, MacDonald JR, McKelvie RS, Green HJ, Smith KM (1998). Muscle performance and enzymatic adaptations to sprint interval training. Journal of Applied Physiology, 84, 2138-2142
- Rodas G, Ventura JL, Cadefau JA, Cusso R, Parra, J (2000). A short training program for the rapid improvement of both aerobic and anaerobic metabolism. European Journal of Applied Physiology, 82, 480-486
- Stepto NK, Hawley JA, Dennis SC, Hopkins WG (1999). Effects of different interval- training programs on cycling time-trial performance. Medicine and Science in Sports and Exercise, 31, 735-741
- Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K (1997). Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Medicine and Science in Sports and Exercise, 28, 1327-1330
