Reader Jeff Yielding asked a good question here yesterday. He noted that in Part 2 I said, “If you keep cutting your volume while continuing to train with high intensity, at some point performance will decline.” So he logically asked what that cut-off point might be. Unfortunately, as you’ve probably come to expect in my blog, the answer begins with “it depends.” It depends on who we are talking about, what brought this person to this point in time, and what type of training he/she will be doing with decreased volume. There is not a single answer that fits everyone. I discovered for myself a long time ago that when training for 2-hour races, for example, I usually needed to do at least 9 hours per week given the type of workouts I would be doing. That isn't necessarily going to be the same for someone else.
This is probably the biggest conundrum serious triathletes face. Trying to train for 3 sports with a fixed amount of training time and energy means something must be cut out. There is always hope that there is some cross-over effect between sports. For example, triathletes generally accept the notion that training on the bike will provide some running fitness. In fact, there is some research that indicates this is probably happening. But the cross-training benefits are not very great. It still comes down to specificity. If you want to become a better runner the best way to accomplish that is by running, not biking and swimming.
Given their limited training per sport, triathletes should come to rely on intervals, especially those done at race intensity, more so than mono-sport athletes. A serious swimmer, cyclist, or runner can make a few mistakes in training and get away with it simply because they train so many hours. When you’ve only got 3 hours of run training in a week, or whatever the number may be for a given triathlete, you simply can’t make mistakes. Every mile must accomplish something positive.
So the fewer hours you have available to train the more important intervals become. I’m sure what most readers would like to see here is examples of different types of intervals and when they are best done. Please be patient with me as I’m getting to that. In part 4 I’ll discuss the nitty-gritty of interval training with examples. I’m sure that will be quite long so I’ll probably cover it in 2 or more installments. For now I want to return to the scientific literature to make a point about how and when to incorporate intervals into your training.
All Intervals All the Time
The study that is most often used by proponents of high-intensity interval training as opposed to long, slow distance training came out of the McMaster University in Ontario, Canada in 2006 [Gibala]. In this study 16 young, active men (please note that they were not highly trained athletes) were assigned to either a sprint-interval training group (SIT) or a high-volume, endurance-training group (ET). Each group did 6 cycling workouts over a 14-day period. The workouts were as follows:
SIT: 6 x 30 seconds at a maximal effort (about 250% of power at VO2max)
ET: 90-120 minutes of steady riding at 65% power at VO2max (about zone 3 using Coggan’s power zones)
Over the 14-day period the ET group rode a total of 10.5 hours while SIT was on their bikes for only 2.5 hours. Both groups improved their time trial performances by similar amounts. Muscle biopsies revealed similar increases in oxidative capacity and muscle acid buffering were the same. All of this simply means that they became equally fit for aerobic cycling (so long as the goal event was short).
The kicker is that SIT accomplished their improvement with less that a fourth of the training time of ET. So if you are pressed for time, high-intensity training is certainly the way to go if you are training for a fairly short race.
The problem here, of course, is that some athletes believe the results of this study mean they should do only intervals and do them year round. A few may be able to get away with that, but I think I’d soon become burned out from trying to get up for high-intensity intervals every other day for 40 or more weeks. In fact, as described in Part 2, I experienced that methodology in college and came to hate running as a result.
But training doesn’t have to be all one way or the other. Here’s another study that used a different protocol, one that more closely follows a periodized pattern used by most advanced athletes.
Seven cyclists trained 1 hour per day, 5 days per week for 6 weeks at about 70% of VO2 max (about upper zone 3 in Coggan’s power zones). On average, their VO2max rose by 10% (53 to 58 ml/kg/min). Their anaerobic capacity performances (roughly Coggan’s power zone 6, my HR zone 5c) did not significantly change. For this 6-week period the subjects were training much as is often done in the late Base period of the season.
Then the same 7 cyclists trained for an additional 6 weeks. Only this time they did only intervals consisting of 7-8 x 20 seconds at 170% VO2max (a power output sustainable for only a couple of minutes for most athletes) with 10-second recovery intervals. this workout, with warm-up and cool down, would take about 20 minutes. They raised their VO2max by an additional 7 ml/kg/min (12%). This time their anaerobic capacities rose by 28%. This training is much the same as might be done in the seasonal Build period. Following this interval-based period they were essentially ready to taper and race.
Does this also mean you should do only intervals, especially high-intensity ones, regardless of the event for which you are preparing? That’s the key question. Again, the answer also has to do with how much time and energy you can devote to training. I’ll get to all of this in my next post.
Gibala, M.J., J.P. Little, M. van Essen, G.P. Wilkin, K.A. Burgomaster, A. Safdar, S. Raha, M.A. Tarnopolsky. 2006. Short-term sprint interval versus traditional endurance training: Similar initial adaptations in human skeletal muscle and exercise performance. J Physiol 575(Pt 3):901-11.
Tabata, I, K. Nishimura, M. Kouzaki, Y. Hirai, F. Ogita, M. Miyachi, K. Yamamoto. 1996. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc 28(10):1327-30.