Mention intervals to anyone that has participated in organized athletics, and you will open a floodgate of memories (often unpleasant) of hard work on the field, in the pool, on the track, around the rink, or down the court. Time after time, interval training comes up as an efficient method for aerobic conditioning and for reducing weight. Interval training works. It improves the performance of high school athletes and it can improve the performance of older athletes too.
Interval training is high intensity work, interspersed with short intervals of rest. The main idea: rest intervals allow more work to be completed at a higher level of intensity than can be accomplished with steady state training.
The modern history of interval training developed to improve running performance (See Lance Smith’s overview – Running Through History or Steve Magness’s Learning From the Past: Training Through the Ages). 20th century runners and their coaches get the credit for developing this training method. Around 1910, the Finn Paavo Nurmi and his coach Lauri Pikhala put together an interval system of training. Also, the Finnish gold medalist (5k, 10k, 8k, and cross-country) Hannes Kolehmainen prepared for his Olympic performances with interval training. These runners focused on alternating fast and slow runs. In some cases they would ramp up the effort, while decreasing the distance. For example, a 4 to 7k run, with fast speed over the last 1 to 2k, immediately followed by four to five sprints. Or, they would start with a set of sprints, followed by a longer distance run (e.g. 3km) at 75-90% of max effort.
By the mid-1930′s, the Swedish coach Gosta Holmer developed a different style of interval training. His style of training called for the athlete to vary the speed based on how they felt. So, during a long run, an athlete may alternate between a fast and a slow pace or between a fast and a medium pace or between a medium and a slow pace. The Swedish word for this type of training is Fartlek or speed play. Fartlek continues to be a very popular form of training for runners.
German coach Woldemar Gerschler, watched the Finns and Swedes and determined that there was an opportunity to include more speed work. With Gerschler interval training reached its modern definition. His system focused on greater intesity of effort, because the periods of rest or light running that followed allowed for partial recovery, prior to the next hard effort.
Interval training faded somewhat during World War II, but re-emerged with Emil Zatopek. Zatopek was an innovative athlete, willing to experiment and vary his training methods. For example, he would run in heavy army boots (they added resistance, were cheap, and lasted well on the rugged trails that he preferred to train on). When he heard that other athletes were lifting weights to gain strength, he experimented with running with his wife on his back. And, he ran intervals. Zatopek would break longer runs into shorter bursts, so that his overall average pace was faster. Zatopek took interval training to previously unheard of levels of intensity and volume.
After Zatopek, the next big breakthrough for runners came from Percy Cerutty in Australia and Arthur Lydiard in New Zealand. Cerutty was known to dislike interval training and his Stotan (stoic/Spartan)training philosophy added resistance training to running. His runners often ran on beaches and up dunes. Lydiard developed the now essential tool of periodization and insisted on high volumes of running by his athletes.
Intervals continued to play a role in training runners, but interval training was only one part of a periodized program that included a high volume of training (with long intervals), dune running, weight training, and simulating race conditions. This training program could be laid out over a set period of time with the goal of preparing an athlete for peak performance at a scheduled key event. Advances in running continued to come, but they were driven by tweaking periodization, training at altitude, introducing plyometric exercises, and understanding lactic acid build-up and VO2 max.
Other athletes, particularly those engaged in multi-sprint sports (soccer, football, basketball, hockey, tennis, and swimming) continue to use interval training, as a key technique for improving cardio-vascular endurance. Intervals have proven to be a better method of training these athletes, because long distance training at 70-80% of maximum heart rate can be detrimental to strength and power. Variations in the duration and intensity of the work period and the duration of rest periods can be tailored to meet the needs of the particular sport.
Experiments with these variables continued and in 1996, Izumi Tabata of the National Institute of Fitness and Sports in Kanoya, Japan published the results of his study on the effects of High Intensity Interval Training. Tabata designed a scientific study of a protocol that was being used by Japanese speed skaters. He compared two groups of athletes over a six week period. The first group engaged in one hour of moderate intensity (70% of VO2 max) steady state endurance training on a stationary bicycle. These athletes trained five days per week.
The second group followed a protocol similar to the one being used by Japanese speed skaters. This group did their work on a stationary bicycle too. After a 10 minute warm up, they engaged in a 4 minute period of 8 intervals with a 2:1 ratio between work and rest. It may help to think of this as 8 sets of 20 seconds of work followed by 10 seconds of rest. During the work phase, intensity was kept high at 270% of VO2 max with pedalling speeds at 90 rpm. If pedalling speed dropped below 85 rpm, the set was ended. If an athlete could complete nine sets at 90 rpm, then the resistance was increased to require 11 watts of additional work during the work sessions. Interval training was followed by a cool down period. One day a week the protocol was changed to allow for 30m of moderate intensity (70% of VO2 max) steady state training, followed by 4 rounds of 20s of high intensity work followed by 10s of rest.
The result:Via: Body Recomposition
As you can see, the Tabata protocol did not exceed the results of the steady state group for VO2 max. However, the Tabata group made substantial gains in VO2 max, particularly during the first half of the experiment. Also, the experiment started with a significant gap in VO2 max between the two groups and over the six weeks, the Tabata group was able to narrow the gap significantly.
The other significant finding is that the Tabata method of training resulted in improvements to anaerobic capacity. Whereas, the steady state training did not improve anaerobic capacity. This makes sense, given that the Tabata group was training for short periods of time at levels that exceeded their aerobic capacity.
Key findings of this study: (1) athletes can achieve good (not maximal) improvement in VO2 max with High Intensity Interval Training; (2) high intensity interval training has some anaerobic benefits for athletes, that cannot be achieved with steady state aerobic exercise alone; (3) compared to the steady state group, less time was required for this type of training.
Coaches and trainers have applied the Tabata protocol to many other exercises. Porting this protocol to a rowing machine or sprints on the track or in the pool is straightforward. However, an interesting set of mutations have occurred. First, coaches and trainers began applying a Tabata inspired protocol to body-weight exercises, such as pushups, pullups, or burpees (8 rounds of 20s of intense effort, performing as many repetitions as possible, followed by 10s of rest). Then, they created circuit training routines, where each station had a different exercise and followed the Tabata inspired 8 rounds of 20s of intense effort followed by 10s of rest (e.g. Tabata This by CrossFit). Next came the incorporation of resistance training exercises, using barbells, dumbbells, and other weights (e.g. front squats and thrusters). These adaptations have become popular in recent years with the rise of CrossFit. Note, these mutations are not following the Tabata protocol, even if they are colloquially referred to as Tabata workouts.
More recently, efforts have been made to develop and study interval training that is less intense than the Tabata protocol. The goal is to retain most of the benefits, while being able to safely incorporate high intensity intervals into general fitness training. A 2009 study by Jonathan Little and Martin Gibala of the Kinesiology Department at McMaster University focused on a two week session of a less extreme form of high intensity interval training. Subjects completed 8 to 12 rounds on a stationary bike with 60 seconds of exercise at approximately 100% of VO2 max, followed by 75s of rest. The results in improved VO2 max approximated the results expected for individuals training for longer periods of time (5 hours per week) at steady state levels. This less extreme form of High Intensity Interval Training has gained traction in the popular press, as people are hoping that the protocol may allow for health benefits similar to longer periods of steady state training (improved cardio-vascular endurance and weight loss) with less time spent on the dreadmill.
As runners discovered, interval training has its limits. Intervals are not a magic formula or universal solution. Although the initial results are positive, before anointing High Intensity Interval Training as the optimum protocol for restoring fitness in the general population, issues remain:
—For individuals training on their own, intensity is not likely to be at Tabata levels and even working at the less intense levels may be a hard sell.
—Does this form of training adequately prepare muscles to perform in an endurance setting? VO2 max is only one element of endurance performance. While a Tabata trained athlete may have adequate VO2 to compete in an endurance event, it seems likely that they may be under prepared in other areas necessary for successful performance. One area of concern is whether muscle endurance is trained adequately.
—Similarly, with Tabata inspired resistance training, what sort of gains can be expected. For example, if my current maximum number of reps for pullups is 15 and I follow a Tabata inspired 8 rounds doing pullups four times per week with a fifth day doing 8 pullups and 4 Tabata inspired rounds, after 6 weeks can I anticipate that my max performance will improve to 18 or 20 repetitions?
—Where are the plateaus? As pointed out in the Body Recomposition piece, the majority of the VO2 gains come in the first three weeks of training and the majority of anaerobic gains come within the first four weeks. Will continued training result in breaking through this plateau, will further training of this sort maintain the new levels of performance, or over time will there be deterioration (burn out)?
Coaches, athletes, and scientists will continue to study and experiment with interval training. Meanwhile, interval training is a versatile conditioning method that you can incorporate into your training. How versatile…check out Indecent Intervals, by John Berardi for some inspiration.
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