Maximum Lactate Steady-State Training Made Easy
How To Find Your Maximum Lactate Steady State Using Muscle Oxygenation (SmO2)
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What Is The Maximal Lactate Steady State (MLSS)?
A common mistake that athletes and coaches make when taking blood lactate measurements is taking them at face value. When a blood lactate measurement is taken from an ear or finger, there is a time lag because the measurement is taken in the systemic circulation rather than at the source of lactate generation in the working muscle.
Additionally, blood lactate measurements do not tell you how much lactate the body has produced, despite most people interpreting the measurement that way. Instead, blood lactate measurements reflect the balance of lactate production and consumption. An athlete's maximal lactate steady state (MLSS), therefore, is the highest power output an athlete can sustain while lactate is produced and cleared at an equal rate, resulting in stable blood lactate values, as measured with a lactate analyzer.
How Is An Athlete’s MLSS Related To Oxygen?
The maximal rate that an athlete can generate and clear lactate from exercising muscle is closely linked to their ability to supply utilize oxygen to said muscle. Thus, it’s unsurprising that you can use an athlete’s muscle oxygenation (SmO2) rate of change to identify their maximal lactate steady state (MLSS) in real-time.
Muscle oxygenation reflects the balance of oxygen supply and demand in exercising muscles. When muscle oxygenation is steady and unchanging, a metabolic steady state has occurred, which means that oxygen supply and demand in the exercising muscles are balanced. The highest output an athlete can sustain with a stable muscle oxygenation value is called their maximum SmO2 steady-state intensity.
Anther way to think of the maximum SmO2 steady-state intensity is the highest power output than an athlete can sustain an SmO2 rate of change of 0%/minute. This threshold happens to correspond with the MLSS, and also closely matches an athlete’s critical power, which is the the highest power output an athlete can sustain without depleting their finite energy reserves.
From a practical standpoint, athletes can observe the rate at which their SmO2 changes to determine how close they are to fatiguing. If the SmO2 rate of change is positive, muscle oxygenation is increasing, and oxygen supply is greater than demand. Thus, the effort is sustainable. On the flip side, if an athlete’s muscle oxygenation is rapidly declining, the SmO2 rate of change is negative, and oxygen demand is greater than supply. The maximal steady state intensity is the gray area between these two scenarios, where an athlete is exerting themself as much as possible while matching oxygen supply to demand. As they deplete their fuel reserve, they will either slow down (thus decreasing oxygen demand), or sustain their effort and gradually deplete their muscle oxygenation until they reach task failure.
How To Perform MSS Training With NNOXX
Maximum steady-state (MSS) training is one of the easiest types of physiological guided training to perform. You can do MSS training with any cyclic exercise modality, including cycling, running, rowing, or cross-country skiing.
MSS training aims to have athletes exercise at the highest power output they can sustain with a stable muscle oxygenation value. To find an athlete's maximal steady-state intensity, they should begin exercising at a low to moderate intensity. After an initial drop in their muscle oxygenation level, their SmO2 value will stabilize. The athlete should then increase their intensity ever so slightly. After an initial drop in their muscle oxygenation value, they should see it stabilize again, indicating that their body's oxygen supply systems can match the muscle's demand for oxygen.
After repeating this process, an athlete will eventually find a power output where their muscle oxygenation level does not stabilize after the initial drop and continues to decline steadily, indicating their working muscles are extracting oxygen faster than it can be supplied. At that point, the athlete has overshot their MSS and should reduce their power or speed until their muscle oxygenation level stabilizes. They should then aim to hold that approximate power output for the duration of the exercise bout, making minor modifications to avoid their muscle oxygenation level declining. As athletes' fitness improves, they should be able to hold progressively higher power outputs at their maximal steady state.
In the instructional above, I explained how to perform MSS training with real-time physiological feedback. However, coaches and athletes can also choose to perform power or speed-based MSS training, then use NNOXX's high-performance platform (HPP) for post-hoc data analysis to guide their week-to-week training progressions. For example, I recently performed a three-minute all-out critical power test on an indoor rower. Critical power represents the greatest metabolic rate resulting in wholly-oxidative energy production and is a reasonable starting power output for maximum steady-state training progressions.
During my first week of MSS training, I rowed for twenty minutes at 245 watts, just below my critical power. After the initial drop in my muscle oxygenation level at the start of exercise, I could sustain a SmO2 level between 40-42% for the twenty-minute work bout. I then repeated the same workout each subsequent week, increasing my power by five watts. On the fifth week of the training progression, I rowed at 265 watts, finishing with a muscle oxygenation value of 36% and a negative ΔSmO2 value.
ΔSmO2 is the rate of change of muscle oxygen saturation, representing the balance of oxygen supply and utilization. Thus, a ΔSmO2 value of ~0%/second indicates that an athlete is at a metabolic steady state, and a negative ΔSmO2 value means that oxygen utilization is greater than oxygen supply and the power output is unsustainable. Once I reached a supra maximal steady state intensity at 265 watts, I adjusted my training progression. Rather than continuing to increase my power output from week to week, I lowered my power back down to 260 watts and increased my total training volume at that intensity while keeping my muscle oxygenation level stable. I could then increase my power above 260 watts later on without ΔSmO2 becoming negative.
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One of the many things that confuse me about lactate is that we don't know where the lactate was produced. For example, in a sport where the entire body is used (eg, rowing, cross-country skiing, swimming), the lactate can be produced in legs or in upper body, but we don't know where it was produced. Say that we determined our "threshold" (using one of 30 methods out there) and use it for training guidance. But isn't that rather meaningless unless we know how we got that lactate? If we measure 3.5 mmol/L and it was produced by arms (one mode in cross-country skiing), the intensity of exercise is certainly very different than if it was produced by both legs and arms (another mode in cross-country skiing). We sure are producing a lot of lactate in the first case and much less in the second case.
How does SmO2 address this problem?
Can we use and apply this for crossfit workouts?