Internal Load
A 5 minute effort at 350 watts might be a comfortable Zone 2 cruise for one athlete and an all-out Zone 5 battle for another.
The external load is the same, difference lies in Internal Load — how much any given effort truly costs the body at that exact moment.
What is internal load?
It is your body's metabolic response to physical and psychological stress. It's extremely individual and continuously changing during exercise.
It shows how much maintaining any effort truly costs your body. The goal of training is to reduce that cost by improving your abilities.
Internal load measurement
mnsX continuously measures the changes in internal load, the internal overload and internal recovery.
It can detect within seconds, precisely, when the external load — bike power or running power — has crossed the internal overload threshold: your momentary Critical Power.
Above that threshold, fatigue accumulates rapidly and the effort becomes unsustainable. Below the threshold, recovery begins.
Manage internal load
Internal Load can only be managed by adjusting External Load, such as power or pace.
momentary Critical Power is the connection between them.
momentary Critical Power
mCP is a new, key parameter which shows the momentary threshold between sustainable and unsustainable internal load.
mCP's value
mCP is a continuously changing, momentary External Load value (bike power, run power). It primarly depends on fatigue.
Overload
Above mCP, the workload becomes unsustainable, internal overload occurs and fatigue accumulates rapidly.
Recovery
After an overload, complete recovery of the aerobic system is crucial — without it, endurance capacity can permanently decline. Below mCP, internal recovery begins.
New technology
mnsX is the first metabolic neuromuscular skin refleX monitor.
It continuously measures the changes in internal load, the overload and recovery, momentary Critical Power and other essential key parameters during training or racing.
It displays the measured data on your watch or bike computer and notifies you of overload via sound alert or vibration (on watch).
Essential data in real-time
Overload
When intensity exceeds the mCP, your aerobic system is overloaded and fatigue accumulates rapidly. The display shows when you approach the threshold, and exactly when you've crossed it.
(Pink: approaching critical threshold — Blue: aerobic system overloaded)
Recovery
When intensity drops below mCP, recovery begins. The display shows the entire process: when recovery starts, how it progresses, and when it's complete. Knowing this, the optimal duration and intensity of every recovery phase becomes easy to define.
(Recovery: green graph above internal load graph. 1 unit: recovery begins/ends — 2 unit: recovery in progress — 3 unit: recovery complete)
Fatigue & Performance Reserve
The declining mCP reveals fatigue accumulation in real time. When mCP drops below your 20-minute CP value, you've likely reached the limit of your high-intensity capacity — time to recover.
The gap between your current intensity and mCP is your Performance Reserve — a live read of how much you have left. Use it to pace your repetitions, or to make smarter decisions mid-race.
Critical Power Curve
a new parameter that primarily characterizes aerobic capacity and defines the boundary of aerobic overload.
What is CP?
Critical Power represents the highest intensity that you can sustain for a given duration without overload. It marks the threshold between sustainable and unsustainable internal load.
CP isn't a single number
Critical Power is not a single value. Instead, it can be determined as a function of duration, forming a curve (CPc).
Aerobic capacity
While W′ characterizes anaerobic capacity, the CPc primarily reflects aerobic capacity.
Built from your measured data
The mnsX system measures in real time, with a delay of 4–8 seconds, when you approaches or crosses the CP level from either direction. This enables fast, precise monitoring of overload and recovery.
Using the real-time measured data, the cloud-based analysis continuously updates your CPc and assigns a confidence value to each point, based on the recency and quantity of measurement data.
Extremely individual
The CPc is unique because its values depend on your individual abilities — aerobic and anaerobic capacity, durability, fatigue resistance, focus, and more. The shape and position of the curve represent the current level of your abilities.
Change of your abilities
The shift in shape or position reflects a change in your abilities. It shows if one of your abilities has improved — as well as if it has declined.
Multiple Curves
Different sports demand different physiological qualities, so each has its own CP Curve. The ArguStress cloud-based analyser updates each CPc separately — ensuring your profile stays accurate across every discipline you train in.
Static vs. Adaptive Training Zones
CPc defines your training zones based on your current abilities.
mCP adjusts them based on your fatigue and momentary state during every session.
Shifting Training Zones
As fatigue builds, your training zones shift. The change in mCP tracks this in real time — showing exactly how your zones move throughout a session.
Maximise time in zone
At a steady intensity, fatigue gradually pushes you through multiple zones. By following the mCP change, you can adjust your effort to stay in the right zone.
Maximise training efficiency
Seeing your zone boundaries in real time makes it possible to stay precisely within that range, significantly improving training efficiency.
Fatigue dependent zones
New Aspect
Defining the CPc makes it possible to move beyond static training zones based on a single value, and instead use ability-improvement zones that run parallel to the CPc — giving you a complete picture of your ability improvement boundaries across every duration.
Planning and adjusting
Building a training protocol around CPc zones is the right starting point. But zones are not static — daily form, fatigue, and recovery all shift them during a session, and your intensity needs to adjust accordingly.
Adaptive Zones
Using mCP-control, mnsX helps you maintain effort in the right fatigue-dependent ability-improvement zone throughout each interval — automatically adapting as your fatigue builds.
Training zone control
One Intensity, Multiple Zones
At a static load, intervals gradually feel harder over time — because fatigue is shifting your zone boundaries. As it builds, a constant intensity drifts across multiple zones, and only a fraction of the interval is spent in the actual target zone.
One Zone, Multiple Intensities
mnsX with mCP-control helps you continuously adjust your target load based on your fatigue state — keeping you in the right ability-improvement zone for as long as possible. It displays the target external load on your bike computer or watch.
Truly Personalised Training
The mnsX real-time measurement system and offline cloud analyzer together guarantee that, according to your momentary state, you spend as much time as possible in the zone that achieves your training goal — completing the targeted ability-improvement task as efficiently as possible. mnsX adaptively manages fatigue-dependent zone boundaries, displaying the optimal intensity in every second, accurate to 1 watt.
