Step 3: Understanding the metrics

Before you read your first real athlete data you need to be fluent in what each metric actually means. This step is a plain-English guide to the seven core metrics you'll see in Soma Analytics.

Read it once to build your foundation. Come back to it as a reference whenever you need to remind yourself what a specific metric is telling you.

Lower is better. Measured in milliseconds.

How fast the brain detects something and sends a signal to respond. The lower the number, the faster the brain.

Good result: The brain is sharp, fast, and processing clearly.

Needs attention: Reaction time is rising across sessions, or slower than this athlete's normal range. What counts as slow depends on the task and the athlete, so compare against their own baseline rather than against absolute numbers. Rising RT usually reflects fatigue, mental overload, or insufficient recovery.

Why it matters: In sport, a fraction of a second changes everything. When reaction time rises, decisions arrive too late. It is the clearest signal that the brain needs rest or reduced load.

Example: 241ms is fast for most tasks. 487ms would be slow on a simple reaction task but normal on a more complex one. Always read RT against this athlete's own baseline.

Higher is better. Measured as a percentage.

The percentage of correct responses during the session. It shows how precisely the brain is making decisions under today's conditions.

Good result: A high percentage, stable throughout the session. Decisions are accurate and the brain is executing cleanly.

Needs attention: More errors are appearing. Mental fatigue, distraction, or cognitive overload is starting to affect decision quality.

Why it matters: Speed is only useful if the decisions are right. When accuracy drops, the brain is making mistakes even if it still feels fast. In a game, those errors cost points.

Example: 94% is high accuracy, decisions are clean. 61% is too many errors.

Lower is better. Measured as a percentage.

Shows how consistent the response times are across the session. A low percentage means responses are reliable and repeatable. A high percentage means responses are erratic.

Good result: Low and stable. Responses are consistent and controlled. The brain is in a good rhythm.

Needs attention:

Rising across the session. Some responses are fast, others slow. The brain is losing its rhythm and fatigue is likely building.

Why it matters: A consistent brain is a reliable brain. When variation rises, performance becomes unpredictable moment to moment.

Example: 12% is tight and consistent. 68% is erratic and the brain is losing rhythm.

Higher is better.

A single score combining speed and accuracy together. It rewards responses that are both fast and correct. The most complete summary of how the brain performed.

Good result: A high score. Fast and accurate. Speed and accuracy are working together.

Needs attention: A low score. Speed, accuracy, or both are not where they need to be. The brain is not working at full efficiency.

Why it matters: RCS is the headline number. It tells you whether the brain is actually performing well overall, not just quickly or just accurately.

Example: 4.2 is strong efficiency. 1.8 is low, speed or accuracy is breaking down.

Higher is better. Calculated as 1000 divided by RT.

Speed is a transformation of Reaction Time. If an athlete responds in 250ms, their Speed is 4.0. If they respond in 500ms, their Speed is 2.0. Higher Speed always means faster processing. Think of it like a speedometer. RT works like a stopwatch where lower numbers mean faster. Speed flips that, so higher numbers mean faster. It's designed to make small improvements more visible than RT alone.

Because Speed is a reciprocal transformation, it's more sensitive to outliers than RT. Very fast or very slow responses pull Speed more than they pull RT. When you're analysing baseline data and see a large percentage change between RT and Speed, that tells you there are outliers in the data, which variation will usually confirm.

Good result: Fast and efficient. The brain is moving through the cognitive demands without resistance.

Needs attention: A low value. The brain is moving through the task with resistance, usually reflecting fatigue, hesitation, or reduced processing capacity.

Why it matters: Speed shows the brain's overall work rate. When it drops alongside rising variation, the brain is working harder but producing less.

Example: 4.1 is fast output. 1.6 is slow, the brain is struggling with the demands.

Higher is better. Measured in milliseconds.

A measure of heart rate variability. It looks at the tiny differences in time between each heartbeat. The higher the number, the more recovered and adaptable the nervous system is right now.

Good result: A high number. The nervous system is recovered and ready. There is capacity to take on load.

Needs attention: A low number. The nervous system is under stress and has not fully recovered. Pushing hard on a low RMSSD increases injury risk and reduces performance.

Why it matters: RMSSD is the recovery signal. A low score means the body and brain have not recovered from what came before. It is the number that tells you whether to push or protect today.

How to read RMSSD: The best way to understand RMSSD is across days. A healthy RMSSD stays consistent. A low or dropping RMSSD means the body has not recovered.

Example: 72ms is ready, the nervous system is prepared for work. 18ms is depleted, the nervous system needs recovery.

Higher is better. Measured in milliseconds.

A broader measure of heart rate variability that reflects overall nervous system adaptability across the full measurement window. Where RMSSD looks at short-term recovery, SDNN reflects overall nervous system health.

Good result: A high number. The nervous system is flexible and adapting well to changing demands.

Needs attention: A low number. The nervous system is rigid and struggling to adapt. This usually reflects accumulated stress, poor sleep, or fatigue built up over time.

Why it matters: SDNN tells the bigger story. A persistently low SDNN is a signal to look at the full training week and ask whether accumulated load is becoming too much.

Think of SDNN like a battery. A full battery means the nervous system is adaptable and ready. A low battery means it is struggling to cope with any more load. Unlike RMSSD which changes day to day, SDNN tells you about the bigger picture. A week of low SDNN is a clear signal that the accumulated load has become too much.

Example: 94ms is full charge, nervous system adaptable and ready. 21ms is low charge, nervous system struggling and needs rest.

Reminder: To track HRV metrics (RMSSD and SDNN) and BPM in real time, connect a Polar H10 heart strap to Soma NPT.

Every metric can be viewed in two ways. Both are valuable, but they show different parts of the story.

The average across all responses. Each dot in a scatter is one response. The mean pulls all responses into a single number that shows how the brain performed overall.

A good mean means data is tight and consistent. Strong result.

A poor mean means data is scattered. Weak result.

Mean tells you what happened.

How the metric changes across each minute of the session. MoM catches whether the brain stayed sharp or started to fade as the session went on.

A stable MoM means the brain is consistent every minute, holding steady.

A fluctuating MoM means the brain is up and down minute to minute, unpredictable.

MoM tells you how it happened.

Start with Mean to get a high-level read. Then look at MoM on any task where the mean looks interesting (really good, really bad, or unexpected), because MoM often reveals why.

A mean that looks fine can hide a fluctuating MoM where the athlete started strong and collapsed in the final minutes. That's not the same as steady performance throughout. MoM catches the difference.

You're about to open your athlete's baseline data in step 8. When you do, you'll see these metrics in action. Knowing what each one is telling you, and the difference between Mean and Minute on Minute views, is the foundation for every interpretation decision you'll make.

You don't need to memorise all seven right now. You need to know they exist, roughly what direction each one should move in, and where to come back to when you need a reminder.

This article is your reference. Bookmark it, come back to it, and let fluency build over time.