This Training Series is Presented by Dynamic Physical Therapy
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Runners, cyclists, and triathletes often ask me, "How can I maximize my training time?" One of my favorite answers focuses on training at a heart rate intensity equal to the Maximal Lactate Steady State (MLSS).
What is Maximal Lactate Steady State (MLSS)?
To explain MLSS in depth, a brief course in exercise physiology is in order. Lactic acid is a byproduct of energy metabolism that is produced in muscle then shuttled into the blood stream where it is converted to lactate.
Muscles have the ability to shuttle only a certain amount of lactic acid as it's produced. At low levels of exercise intensity, the shuttling ability of the muscle keeps pace with lactic acid production quite easily. The energy system to produce this type of power is through aerobic metabolism.
Exercise can be maintained at this level for several hours. However, with increasing levels of exercise intensity, the rate at which lactic acid is produced will eventually exceed the rate at which it's eliminated.
Subsequently, lactic acid backs up in the muscle producing that familiar burning sensation, and as a result exercise intensity is forced to decrease. The energy system to produce very high levels of power is through anaerobic metabolism. Exercise can be maintained at this level only for several minutes.
MLSS is the point where power output is at its maximum, but the majority of the energy for the work effort comes from aerobic metabolism. It corresponds to the maximum point at which the level of lactic acid in the muscle remains stable. Exercise can be maintained at MLSS for roughly 60-90 minutes.
One analogy that helps describe MLSS is a funnel and water scenario in which the water is lactic acid, the funnel is the muscle, and the height of the water in the funnel is power output. If the water (lactic acid) is poured into the funnel (muscle) slowly, it doesn't back up at all. However, the height of the water (power output) in the funnel remains very low. This example equates to several hours of riding at a leisurely pace.
Conversely, if the water (lactic acid) is poured in very quickly, the water in the funnel (muscle) backs up to the maximum height (power output) and eventually overflows. This example equates to riding up a short climb at a maximum pace. However, there is a point in the system where the water (lactic acid) can be poured into the funnel (muscle) quickly at first, causing the water level to rise in the funnel right up to the point where it just about reaches the top of the funnel.
If at that point, the speed at which the water is poured is reduced, it is possible to keep the water from overflowing the funnel but the height of the water (power output) remains very high. This example equates to MLSS.
Don't confuse it with Lactate Threshold (LT)
MLSS should not be confused with the Lactate Threshold (LT). Lactate threshold is the first equilibrium point at which the rate that lactic acid being produced in the muscle equals the rate at which the muscle can shuttle lactic acid into the bloodstream.
To explain LT, let's go back to the funnel analogy. LT is the point at which the water first begins to back up in the funnel but does not account for the fact that more water could be added to the funnel to achieve a higher water level (power output), as seen with MLSS, but without overflowing the system. In this regard, it is better to train at MLSS than at LT, because the water level (power output) is higher and greater fitness can be achieved overall.
What does this all mean for an athlete's training?
With undisciplined high-intensity training, where training partners may take repeated turns ramping up the intensity in an attempt to show who's the strongest, a majority of the workout may be spent either above or below the MLSS heart rate.
However, for races in which sustained efforts at high intensity are required to be maintained for 60-90 minutes, such as with the time trial event in road cycling, sprint distance triathlons, and 10-20 km running races, training at MLSS for prolonged periods of time may be much more advantageous because the maximum amount of power can be applied without entering an anaerobic state therefore making training more event-specific.
Typically training sessions for MLSS are performed in bouts of 20-30 minute work efforts repeated 2-4 times with short 5-10 minute recovery cycles at a HR and/or power output that has been established to correlate with MLSS. Total training duration should last around 2 hours.
Training at other intensities to focus on endurance, recovery, and speed is also in order. And of course, not every workout should be performed at MLSS with sessions limited to 1-2 times per week including races.
However, if training time is squeezed between family and work commitments, incorporating a session or two at MLSS into your training each week can be a great way to maximize training time.
About: Dynamic Physical Therapy is this year's 2008 Morgantown Area Grand Prix (MAGP) title sponsor. Dynamic utilizes a combination of hands-on techniques, therapeutic exercise, and cardiovascular wellness so their patients will truly experience "Health in Motion." Visit one of their four offices in Westover, Fairmont, Jane Lew, and Mannington, WV.
