What Is Momentary Muscular Failure And What Does It Look Like?

I wanted to take a moment to delve deeper into the concept of training to Momentary Muscular Failure (MMF) or, if you prefer, Fatigue, which we discussed in our recent posts about “The Primary Objective of Exercise” and Breaking Through Plateaus.”

Firstly, it’s important to clarify that while training to MMF is a valuable approach, our main goal is to stimulate your muscles effectively and efficiently, rather than solely focusing on reaching MMF. Our aim is to provide you with the tools to improve safely and optimize your training outcomes.

One key principle we emphasize is “Progressive Overload,” applying this principle may enable you to make progress in your training for a considerable time without necessarily reaching true MMF. However, as you continue to advance, training to your limit or MMF may become necessary to sustain progress.

In simple terms, MMF refers to temporarily weakening the targeted muscles during exercise—a scientific term called “Inroading.” While it is natural for us to avoid this state of fatigue, considering our protective instincts, understanding the benefits from a scientific perspective empowers us to willingly create the necessary stimulus.

From an evolutionary biology standpoint, reaching a state of deep muscular fatigue or weakness was considered dangerous for our survival. If, for instance, you were being chased by a tiger and your legs became too fatigued to continue running, your chances of survival would diminish. However, if you were fatigued but still capable of reaching safety, your body would recognize the danger and allocate resources to build stronger legs, enhancing your likelihood of surviving future dangerous situations. Although it is against our nature to embrace fatigue during exercise, comprehending the scientific rationale behind it helps us intentionally create the required stimulus, despite our protective instincts.

From a scientific perspective training to MMF optimizes motor unit recruitment by engaging both slow and fast twitch muscle fibers. By employing slow and controlled movements, you can recruit these motor units safely and efficiently. The higher threshold fibers, which have a greater potential for muscle hypertrophy and strength development, are typically activated in the later stages of a set taken to MMF. Therefore, stopping short of MMF may result in suboptimal training stimulus.

Now, let’s explore what I refer to as “True” MMF. This represents an event where immense mental focus and directed physical effort are required. While it may not be essential to reach “True” MMF to achieve your goals, I believe the psychological rewards outweigh the physical ones. It is a distinction between reaching a point where you can’t push any further (Volitional MMF) and truly giving your absolute best effort (True MMF). Training to “True” MMF is a personal challenge that can enhance your training intensity and focus.

Training to “True” MMF while maintaining excellent form and command over your body, mind, and spirit most certainly can be a “Path of Mastery.”

Let’s explore further what I mean by “True” MMF and how it looks in practice. Here’s an example of performing a set of 4 SuperSlow reps on the Medx Leg Press machine to reach MMF:

Before you start, visualize yourself setting the intention to give your best and most focused effort. Stay calm, control your breath, and connect with the movement. Picture your body in the proper position: feet parallel, knees flexed at 90 degrees, hips firmly pressed into the seat back, head and neck neutral. Imagine building tension and pressing through the ball, outside, and heel of your foot until the weight stack begins to move slightly. Feel in total control of the movement, engaging your glutes, quadriceps, and hamstrings, and activating your core to stabilize your pelvis.

As you reach the end of the range of motion, stay in control and maintain tension, then slowly start the descent. Gradually slow down even more, anticipating the start of the next rep as slowly as possible. Visualize this process for the first 3 reps, focusing on feeling your muscles engage. Embrace the burning sensation and shift your focus towards it instead of avoiding discomfort. Remind yourself that this feeling is a positive sign of progress. As you begin the last rep, give it your all. Imagine barely moving the weight, even if doubt creeps in about finishing the rep. Stay focused on the process, remaining calm and engaged.

When it feels like the weight won’t budge any further, increase your effort without speeding up. Push yourself to maintain an extremely slow speed to keep the weight moving. By this point, you’re nearing the end of the perfect set, barely completing the positive phase of the exercise. Now, concentrate on finishing the perfect rep by controlling the negative phase for 10 seconds. If you can control the descent, attempt to start the next rep. Remember, whether or not you can complete the rep doesn’t matter. The key is to stay fully engaged mentally and physically, with the intention to remain engaged regardless of whether the weight moves or not. Maintain this intention for another 5-10 seconds.

Regarding the above description, I’d like to provide some feedback to guide you on your journey to MMF. As the movement of the weight slows or bogs down, you’ll need to increase your effort to maintain a continuous movement. In the beginning of a SuperSlow set, you intentionally conserve your effort to move at a slow speed. However, as the set progresses and your muscles fatigue, your effort must increase. If increasing your effort causes the weight to move rapidly, it indicates that you’re not as fatigued as you thought. Use this feedback to realize that you can push further before the need to try moving faster arises.

To help you assess your journey towards MMF, here are some indicators that you may not be training to “True” MMF:

1. Arriving late for your training session and allowing distractions to divert your focus and energy.
2. Arriving for your training session with low energy and negative body language.
3. Arriving early for your training session but rather than preparing your mind and body for the session, allowing yourself to become distracted by checking your phone for messages or scrolling social media.
4. Checking your Apple Watch or other devices for messages during your workout.
5. Engaging in conversations during a set of exercises.
6. Making excuses before even starting your training session, anticipating a subpar performance.
7. Worrying about conserving energy for the rest of your day.

These situations are common, but recognizing how they might hinder your progress is crucial to addressing them effectively.

I hope this detailed explanation sheds light on the concept of MMF and its role in optimizing your training outcomes. Our aim is to empower you with the knowledge and guidance needed to reach your full potential. Should you have any questions or require further assistance, please don’t hesitate to reach out.

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