Statistical Analyses Since not all variables passed the normality test, all results are presented as median values with the corresponding inter-quartile range IQR. Baseline At baseline, no statistically significant differences were observed between the LF- and HF group with respect to age, height, weight, VO 2max or training volume Table 1. Training Load in the Intervention Period There was no difference in the weekly training load between groups in terms of training volume, intensity distribution, or resistance training during the intervention period Figure 1.
Time-Trial Performance In the LF group, seven out of nine subjects showed an improvement in rollerski time-trial performance following the intervention, with median time-trial time that was statistically significantly lower at post-intervention Figure 2.
Figure 3. Figure 4. Exercise Economy A statistically significant reduction in submaximal oxygen consumption at Figure 5. Figure 6. Discussion The main finding in the present study is that highly trained cross-country skiers and biathletes performing two longer high-intensity interval sessions per week LF group for a period of 12 weeks, showed a statistically significant improvement in 8 km rollerski time-trial performance.
Rollerski Time-Trial Performance The improvement in the time-trial performance in the LF group is in line with that presented by Seiler et al. VO 2max Test The present findings of no statistically significant change in VO 2max in either group is in accordance with findings from previous studies with well-trained cross-country skiers following a similar length training intervention [ 19 , 20 ].
Conclusions In a group of elite endurance athletes, two long interval sessions appeared to be more effective than four shorter sessions per week in promoting endurance adaptations and performance improvements. Author Contributions Conceptualization, E. Funding This research was funded by the Norwegian Olympic Federation. Conflicts of Interest The authors declare no conflict of interest. References 1. Billat V. Physical and training characteristics of top-class marathon runners.
Sports Exerc. Seiler S. Intervals, thresholds and long slow distance: The role of intensity and duration in endurance training. Sport Sci. Hvorfor ble de Beste Best? Reindell H. Intermittent runs at the velocity associated with maximal oxygen uptake enables subjects to remain at maximal oxygen uptake for a longer time than intense but submaximal runs.
Hurley B. Effect of training on blood lactate levels during submaximal exercise. MacDougall D. Continuous vs. Smith D. The 10 day aerobic mini-cycle: The effects of interval or continuous training at two different intensities. Sports Med. Daniels J. Interval training and performance. Daussin F.
Improvement of VO 2max by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training. Laursen P. The scientific basis for high-intensity interval training: Optimising training programmes and maximising performance in highly trained endurance athletes. Rozenek R. Physiological responses to interval training sessions at velocities associated with VO 2max.
Strength Cond. Helgerud J. Aerobic high-intensity intervals improve VO 2max more than moderate training. Sandbakk O. Effects of intensity and duration in aerobic high-intensity interval training in highly trained junior cross-country skiers.
Adaptations to aerobic interval training: Interactive effects of exercise intensity and total work duration. Wenger H. The interactions of intensity, frequency and duration of exercise training in altering cardiorespiratory fitness. Wakefield B. Influence of work-interval intensity and duration on time spent at a high percentage of VO 2max during intermittent supramaximal exercise. Howley E. Criteria for maximal oxygen uptake: Review and commentary.
Losnegard T. The effect of heavy strength training on muscle mass and physical performance in elite cross country skiers. Ronnestad B. Effect of heavy strength training on muscle thickness, strength, jump performance, and endurance performance in well-trained Nordic Combined athletes. Jones A. A five year physiological case study of an Olympic runner.
Rusko H. Development of aerobic power in relation to age and training in cross-country skiers. Bangsbo J. Estimation of lactate release from contracting muscles in man. Acta Physiol. Holloszy J. Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. Egginton S. Physiological factors influencing capillary growth.
Effects of 12 weeks of block periodization on performance and performance indices in well-trained cyclists. Hopker J. Changes in cycling efficiency during a competitive season. Tokmakidis S. Failure to obtain a unique threshold on the blood lactate concentration curve during exercise. Sahlin K. Metabolic factors in fatigue. Hansen A. Skeletal muscle adaptation: Training twice every second day vs.
Support Center Support Center. External link. Interval training is a potent weapon for torching body fat, raising cardiovascular fitness and boosting blood flow to your brain, which is why all the best professional athletes build interval workouts into their training schedules. So, we decided to bring you some of the best hacks from the pack.
Structured around short, sharp bursts of exercise that are easy to weave into your daily schedule, these high-performance workouts are designed to shed unwanted weight, crank up fat-burning metabolism, and enhance fitness levels. They will also improve your lactic threshold — enabling you to exercise at a higher intensity before a build-up of lactic acid flames your muscles — and release mood-boosting endorphins, helping to sharpen your body and mind.
It is mainly power-based activities like squat jumps, Olympic lifts, clean and jerks, and weighted chin-ups. I need a level of fitness which allows me to recover fast. These different methods are shown in Figure 2. To explain the training methods athletes use, we use the term training intensity distribution TID , which means how an athlete distributes their training across the three intensity zones. Several TIDs are commonly used by athletes and have been studied by scientists.
Using the three-zone intensity model we have described, the following TID patterns are possible Figure 3. There is a lot of variation in the number of hours per year that endurance athletes train and the way they train. Scientists have found that these athletes train up to times per year, in about 8—14 workouts a week.
This means more than one workout a day on some days! There is also a lot of variation in the way endurance athletes space out their training over the course of the year. But, there seems to be a pattern across the training season, from a focus on high-volume, low-intensity training HVLIT during the preparation phase the 5—6 months training period at the start of the training year , toward a pyramidal TID during the pre-competition period the 1—2 months before the first competitions start , and a polarized TID during the competition phase the 3—5 months where the main competitions take place Figure 4.
The monthly frequency of Zone 3 sessions high intensity increases from preparation phase to the pre-competition phase and remains unchanged throughout the competition period, while the amount of Zone 1 decreases. However, in almost every study, the polarized group achieved the greatest improvements. The majority of the experimental studies looked at the training behaviors of recreational or amateur athletes.
However, in one of our recent studies on well-trained endurance athletes, we also found that the polarized TID resulted in the greatest improvements in endurance performance, followed by high-intensity training HIT , while a HVLIT or Threshold TID was not effective [ 3 ]. One explanation of why a polarized TID works best as a training method could have to do with the way the body gets energy during the single training workouts.
In general, the body can produce energy from either carbohydrates or fats. These numbers can be used to calculate how much energy is used in total and how much is spent with respect to energy from fat or carbohydrates with different types of TIDs. For instance, when a polarized TID is used, an athlete can train longer and spend more time in Zone 3 with about the same total energy needed but substantially lower use of carbohydrates when compared with a TID with lot of Zone 2 training e.
Another suggestion as to why a polarized TID works best is that the steady switch between Zones 1 and 3 keeps the athletes from getting bored. It is also possible that low intensities are more helpful for the muscles while high intensities are more important for the heart and the nervous system.
This probably does not happen when training is only in Zone 1. There was not really much of a need for them to spend a lot of time in Zone 2. Several studies have shown that HIT can help to improve the performance of endurance athletes. The data show that approximately two HIT sessions per week may increase performance without being too stressful on the body. On the other hand, the data showed that too many HIT sessions over a longer period might not help performance and might actually lead to overtraining, which can result in a performance decrease and long-term symptoms of exhaustion [ 3 , 4 ].
We still do not understand why a successful endurance athlete needs to spend so much time training at this level. As we said earlier, the studies have shown that with HIT, athletes get the same or even greater improvements in performance than they do from HVLIT, but in a much shorter time.
In summary, the current scientific research proposes that a pyramidal or polarized TID with a substantial amount of Zone 1 training combined with some Zone 3 training is the best way to maximize endurance performance. But, there are still several unanswered questions. For instance, the long-term effects of some TIDs like inverse polarized or HIT on elite endurance athletes are still not totally understood. The choice of the TID also depends on the amount of time that is available for the athlete to train.
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