Steady State Interval Training
People want simple answers to complex questions. Athletes are people. Athletes want simple answers to complex questions. The last thing you want to hear is “it depends.” Either you believe in high volume or high intensity. More is less or less is more? Actually, it turns out that more is more and less is less. Let’s not make it more complicated than it already is. A sure turnoff is to be told one’s ideal training load is a combination of proper volume and intensity, rest and recovery, undulated and periodized over time, determined by training history, current fitness level, and total life stress, and individual to one’s unique physiology. Deep breath, let’s start over.
Before my triathlon career I was a mediocre collegiate distance runner. I noticed I really struggled with a certain type of workout called tempo workouts. I could hang on the long runs and the shorter intervals, but the long intervals were tough. My VO2 max was high enough to get through the 2-5 minute intervals, and my basic endurance could carry me through a Sunday 15-miler, but set me up with 4 x 2 miles at 10k pace and I couldn’t fake it. The truth is, I was probably just under-trained.
A staple workout type in my own training and that of our athletes has been Steady-State Interval Training. When we talk about steady-state intervals, the scientific term we are referring to is “Maximal Lactate Steady State” (MLSS). Technically it is the highest steady intensity at which blood lactate concentration varies by less than 1 mmol/L during the final 20 minutes of constant workload. Based on “research,” well-trained endurance athletes can maintain this intensity for about 40-60 minutes. For an elite runner that might be close to half marathon pace, but for most of us closer to 10k race pace. For a cyclist, it will be very close to a 40km time trial, or very close to your threshold power.
I think this type of training is challenging and it requires the most focus and discipline, because it is so tempting to back off or quit. It isn’t interesting, glamourous, or creative. It’s all about repeatability. Remember that variety is for the weak-minded (wink wink). Typically, the intervals are long (8-20 minutes), and the rest is 50% or less of the interval time. A simple workout to start with might be 3 x 10 minutes with 5-minute active recovery between. Start with around 30 minutes of total time at MLSS and progress to 40+ minutes depending on your goals and training history. For running, I would rarely go over 40 min at MLSS, but cycling I will occasionally push it closer to 60 minutes with something like 5 x 12 minutes. The goal is to maintain the same intensity throughout each effort and from your first to last bout.
A study published in 2004 (Billat, Sirvent, Lepretre, Kortalsztein) studied the effect of 6 weeks of steady-state training. The subjects of the study were well-trained, veteran distance runners and on average, they initially could run at 7:00 min/mile pace for 44 minutes. After six weeks of training and 12 steady-state exercise sessions, they could run 6:23 min/mile pace for 63 minutes (average). They not only increased time to exhaustion by 50%, but their speed increased significantly. Statistically it was a small change in velocity, but for a runner the difference in pace equates to about 4 minutes faster for a 10k and over 8.5 minutes faster for a half marathon! If only time to exhaustion had increased then I would be more skeptical of the fitness benefit for events under one hour, but the fact that speed at MLSS increased significantly indicates that there would be performance benefits for all common triathlon distances.
Suunto Movescount Example: CompuTrainer 4 x 9 minutes at 95% FTP, 3 min active recovery
Most lab testing for Maximal Lactate Steady State takes multiple days of testing to properly determine, but a good estimate can be determined by simple field tests found here.
Be a little conservative because field testing can slightly over-estimate MLSS, so use about 95% of your functional threshold speed or power. Also, don’t call in your testing numbers with your 10k PR from 15 years ago on that point-to-point downhill course of questionable length. Do a field test and get some honest current numbers to work with. Once you have your field testing results, plug them into the calculator here:
Now get out there and train!
Billat, V., Sirvent, P., Lepretetre, P., & Koralsztein, J. (2004). Pflügers Archiv – European Journal of Physiology. Training effect on performance, substrate balance and blood lactate concentration at maximal lactate steady state in master endurance-runners, (447), 875-883. doi:10.1007/s00424-003-1215-8