A DIY Guide To Physiologically Guided Training

What Is Physiologically Guided Training?

How hard should I push myself during training? How many intervals should I do, and how long should each be? Is active or passive recovery better for me? Until now, there haven't been easy answers to these questions. But, with NNOXX, you can get real-time biomarker feedback during exercise, allowing you to fine-tune your training with physiologically guided workouts. 

The idea behind physiologically guided training is to do your own workout with your goals and training plan in mind. At the same time, NNOXX's mobile app displays your data in real-time, helping you auto-regulate your exercise intensity, volume, or recovery. 

Using real-time physiologic data to guide training requires thinking beyond traditional power, speed, or pace-based endurance training prescriptions. Additionally, it forces you to reconcile the difference between internal and external measurements of exercise intensity and load. For example, let's say you run a mile in 5 minutes today, then again next week. Your external load is the same in both cases because you cover the same distance in the same amount of time. However, your muscles may experience different physiological stress levels these days. As a result, your internal load is different. 

This same concept applies within a workout as well. For example, say you're running 400m repeats on the track at a fixed pace. Your external load would be the same for each interval, but that doesn't mean your internal load would be since your muscles may experience different metabolic stressors from set to set.

A major limitation of external load-based training is that it doesn't account for day-to-day or within-day variations in muscle function and performance. To truly individualize workouts, and maximize their effectiveness, you need real-time data. NNOXX was developed with this use case in mind. In the next few subsections i'll teach you how to use NNOXX's mobile app for performing physiologically guided training.

Physiologically Guided Training – The Basics

To perform physiologically guided training, NNOXX users should log in to their account in NNOXX’s mobile app and select the unguided workout mode. They should then attach their NNOXX wearable to the primary locomotor muscle for their chosen activity. The vastus lateralis muscle (i.e., outer quadriceps) is the preferred measurement location for activities such as running, cycling, or rowing. For other activities, a different sensor placement may be preferred. 

Physiologically Guided Training – Maximum Steady State Training

One of the easiest types of physiologically guided training to perform is maximal steady-state (MSS) training. 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, while writing this article, I 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.

Physiologically Guided Training – Rapid Desaturation Training

Mitochondria are best known as the powerhouse of cells due to their ability to generate chemical energy in the form of ATP. As a result, Mitochondria play a crucial role in cellular function and exercise performance, and athletes across various sports require time-efficient training methods to improve their mitochondrial density and muscle oxidative capacity. 

Rapid desaturation training is designed to increase tissue capillarization, mitochondrial density, and an athlete's maximal rate of oxygen utilization. This training method must be performed at a near-maximal intensity with an interval long enough for muscle oxygen saturation to reach a minimum value. If muscle oxygenation has not reached a minimum value within twenty seconds, the athlete should increase their intensity. 

Additionally, the total number of sets for this style of workout should be individualized based on an athlete's real-time physiologic response. For example, we want an athlete to perform as many sets of rapid desaturation training as possible until they can no longer deoxygenate the working muscle to the same nadir as previous sets or they cannot recover their muscle oxygenation back to the same baseline level during fixed-duration rest periods. 

An example of a physiologically guided rapid desaturation workout

Physiologically Guided Training – Extended Desaturation Intervals 

One of the most important considerations when training respiratory-limited athletes is that the amount of work accumulated at a high percentage of their peak oxygen consumption is a primary determinant of performance. However, the amount of training volume that an athlete’s muscles, bones, and joints can tolerate week after week is finite, limiting how much work they can conceivably do at a high percentage of their peak oxygen consumption.

One way to circumvent the issues above is to perform extended desaturation intervals. Extended desaturation intervals induce higher mean oxygen consumption levels than traditional interval training methods, making them ideal for accumulating more time at a high percentage of an athlete's VO2 peak with less wear and tear.

Extended desaturation intervals aim to have an athlete exercise at a high intensity, with a fixed power output, that causes them to utilize oxygen in the working muscles at a greater rate than it can be supplied, resulting in rapidly declining muscle oxygenation levels. Once muscle oxygenation stops declining and plateaus at a nadir, the athlete should stop exercising and begin their rest period. They should then rest until SmO2 stops increasing and levels off at a peak value, then repeat this process for two to six total sets. 

An example of a physiologically guided extended desaturation interval workout

Physiologically Guided Training – Gradual Desaturation Internals

When you exercise, oxygen levels in the working muscles decline, causing nitric oxide (NO) to release from red blood cells—NO signals for small blood vessels to dilate, increasing muscle blood flow. When small blood vessels dilate, the heart must stretch and pump harder and faster to maintain blood pressure. When done frequently enough, this type of training causes your heart to adapt, resulting in increased cardiac output.

To maximize your cardiac output, you can perform workouts that progressively deoxygenate your exercising muscles to a minimum oxygenation (SmO2) level, resulting in NO levels reaching their peak concentration. During these workouts, your heart will progressively pump harder and faster, up to its tolerable limits. At that point, you'll achieve peak cardiac output levels.

Once your muscle oxygenation (SmO2) is no longer declining and nitric oxide (NO) levels are no longer increasing, you should cut your work interval short. In the image below you can see an athlete’s SmO2 and NO levels during three gradual desaturation intervals on a concept 2 rower.  

My  recommendation for athlete’s performing gradual desaturation training is to  aim for 2:00-6:00 of work per interval. You can repeat this process 3-6 times in a workout, resting 3:00-5:00 between sets.

An example of a physiologically guided gradual desaturation interval workout

Physiologically Guided Training – Active Recovery 

During active recovery training, the goal is to increase an athlete's muscle oxygenation as much as possible, which will help aid in recovery. Because every athlete's physiology and response to exercise are unique, their active recovery sessions will also need to be. 

For example, many strong and muscular athletes have trouble doing true low-intensity work. In these groups, heart rate is not a reliable indicator of how much stress they impose on a given activity. For example, in the image above, we have a muscle oxygenation (SmO2) trend from a Crossfit athlete performing a 20-minute active recovery echo bike ride at a heart rate of 110-120 beats per minute.

Note the drop in muscle oxygen saturation (SmO2) mid-way into the work bout, followed by a maintenance of low muscle oxygen saturation. When muscle oxygen saturation is low oxidative metabolism is compromised, which leads to an increased reliance on glycolysis to replenish phosphocreatine, and, subsequently, ATP. In other words, this type of training is anything but active recovery. 

Athletes will find certain modalities where they cannot exercise without rapidly deoxygenating the working muscles. For example, many athletes cannot run with a stable or increasing SmO2 level and will have to walk to achieve that goal. So, the goal for each athlete is to find the right combination of modality, intensity, and cadence that allows them to maximize their muscle oxygenation level over time during active recovery workouts. 

An example physiologically guided active recovery session