WORKOUTS ANALYSIS
Understand your workout summary and key metrics
July 29th 2026・by Andrej Mihelič
GENTLER 101
FITNESS
TRAINING
Workout summaries are full of data. Knowing what each number means and how to interpret it gives you actionable insight for future training, and confirmation that you're on the right path. At first, all these numbers can feel overwhelming. But the more time you spend with them, the more you understand, and the clearer the picture becomes. It's rarely about one metric alone: comparing them together is what reveals the quality and intent behind a workout.
Summaries can offer tons of data, from key stats (duration, distance, elevation gain, heart rate, power, cadence and more), to heart rate and power zones, breakdowns by split, segment and interval, and performance charts. Not every workout shows all this data. What's available depends on the workout type: a swim, for example, won't carry the same metrics as a run or a ride.
Key Stats
At the top of the summary, Key Stats give you a snapshot of the whole session:
Duration: total time of the workout.
Training Load*: a score representing the physiological impact of the session.
Distance: total distance covered.
Elevation Gain: total ascent during the workout.
Average Heart Rate: your heart rate averaged across the whole session.
Average Cadence or Strokes: steps per minute for running, pedal revolutions per minute for cycling, or strokes per minute for swimming.
Average Power: average power output for running and cycling workouts.
VO₂ max: your estimated aerobic capacity for the session.
Average Speed or Pace: average speed, or pace depending on your unit preference, for the session.
Active Energy: estimated calories burned during the workout.
Average Weighted Power*: a smarter average that gives more weight to harder efforts, better reflecting the true physiological cost of the session.
*Available in The Outsiders
Together, these numbers answer the basic question: what did you just do, and how hard was it?
Gentler Streak and The Outsiders offer a similar overview of the workout summary, starting with a map (where available) and key stats. More advanced metrics are available in The Outsiders only.
Zones
Just below Key Stats, Zones show how your effort was distributed across the workout, by intensity rather than by time or distance. Toggle between views to check whether your effort matched what you intended, aerobic base building, threshold work, or an anaerobic push.
Training Focus Zones: a simpler three-zone view, Low Aerobic, High Aerobic and Anaerobic. Learn more about Training Focus Zones and intensity distribution in Why intensity distribution matters.
Heart Rate Zones: time spent in each of your five heart rate zones.
Power Zones (cycling): time spent in each cycling power zone.
Gentler Streak shows heart rate zones, while The Outsiders adds Training Focus zones and cycling power zones for a fuller view of intensity distribution.
Breakdown
The Breakdown section splits your workout into smaller pieces so you can see how your effort changed over the course of the session. Three types are available, depending on the workout.
Splits
Splits divide your workout into equal distances, typically 1km and 5km for running, 5km and 10km for cycling, and 100m, 50m and 25m for swimming, or their mile and yard equivalents if you use imperial units. They are generated automatically for every workout, giving you a consistent way to compare pace, power and heart rate, among other metrics, at fixed distances.
Segments
Segments (also known as laps in some apps) are sections you mark manually, on your Apple Watch or another tracking device, to flag a stretch of the workout you want to analyse separately. Use these for a climb, a specific loop, or any part of the session that matters to you.
Intervals
Intervals come from structured workouts, sessions built with the Apple Watch Workout app or another compatible tracker that includes work and recovery blocks. The app detects these automatically and breaks the summary down interval by interval.
In the Breakdown, splits, segments and intervals show:
Speed/pace
Distance (segments and intervals only, since every split is itself a fixed distance)
Average and max heart rate
Average and weighted average power*
Elevation gain
Average cadence
Relative Intensity*
Variability Index*
Efficiency Factor*
*Available only when power data is present, from a power meter on the bike or an Apple Watch Series 6 or SE or newer, with watchOS 9 or newer for running.
This level of detail lets you see the relationship between heart rate and power, and between speed, distance and elevation gain, for each part of the workout. It also makes progress easy to spot: compare the same split, segment or interval across sessions to see whether you're getting faster, holding power steadier, or working more efficiently.
Gentler Streak keeps splits simple and quick to scan, while The Outsiders' Breakdown goes much deeper, adding segments and intervals alongside far more data per split. Gentler Streak offers a clearer, easier to digest overview, while The Outsiders can be overkill for some, but a data heaven for geeky athletes.
Charts
Below the breakdown, four charts let you see the workout unfold over time: heart rate, speed/pace, power and elevation. Viewing them together helps you connect cause and effect, for example a heart rate spike that lines up with a hill, or a power surge on a specific segment.
Both apps chart heart rate, pace or speed and elevation gain, each styled to match its own look, while the power chart is available in The Outsiders only.
Advanced Workout Metrics (The Outsiders only)
Advanced workout metrics show how hard you worked, how efficiently, and how well your body held up as the effort built. For cycling, all four are built on Weighted Average Power, a smarter average that weights harder efforts more heavily to reflect the true cost of a session. For running, Relative Intensity uses lactate threshold heart rate instead.
Relative Intensity
Relative Intensity (RI) shows how hard a session was compared to your personal limit: Weighted Average Power against FTP for cycling, average heart rate against lactate threshold heart rate for running. It's calculated by dividing your Weighted Average Power by your FTP.
f(x)
An RI close to 1.0 means you were working right at your threshold, the kind of effort sustainable for about an hour. Below 1.0, the session was easier. Above 1.0, you were pushing beyond threshold, sustainable only in short bursts. A one-hour criterium, a four-hour endurance ride and a tempo run all feel completely different, but RI reveals how close each came to your physiological ceiling, on the same scale, useful for comparing efforts across durations, terrains and workout types. Track RI over time to check your training load is balanced: consistently high values suggest stress may be building up, consistently low values suggest room to push harder.
Variability Index
Variability Index (VI) shows how steady your power output was during a session. It's calculated by dividing your Weighted Average Power by your Average Power.
f(x)
A VI close to 1.0 means smooth, consistent effort, what you want for tempo runs and endurance rides. A higher VI reflects surges and recoveries, expected in intervals, hill repeats or variable-pace races. Neither is inherently better; it depends on what you planned to do. Track VI over time: a declining trend, if you're working on even pacing, signals sharper execution. It also adds context to Decoupling, which is most reliable when VI stays low.
Efficiency Factor
Efficiency Factor (EF) measures how efficiently your cardiovascular system converts effort into power, power per heartbeat. It's calculated by dividing your Weighted Average Power by your average heart rate for the session.
f(x)
A higher EF means you're generating more power without your heart working harder, a sign of strong aerobic conditioning. A lower than usual EF can point to fatigue, a fitness dip, or external factors like heat and dehydration. EF is personal: track it across comparable sessions rather than against anyone else's numbers. Paired with Decoupling, a high EF with minimal drift confirms a well developed aerobic engine, while a lower EF with more drift suggests your aerobic base needs work.
Decoupling
Decoupling compares your Efficiency Factor in the first half of a session to the second half. If EF holds steady, you have low decoupling; if it drops, your heart is working harder for the same output, giving higher decoupling, known as heart rate drift.
f(x)
Low decoupling, generally under 5%, means your cardiovascular system held up well over the full session. Higher decoupling points to fatigue, an underdeveloped aerobic base, heat or dehydration. It's most reliable in steady, sustained efforts, tempo runs, threshold rides, long aerobic sessions, where VI stays close to 1.0. In sessions with higher variability, decoupling can still reveal useful trends, but the signal is noisier, since some drift may come from pace or power fluctuations rather than genuine fatigue. Track it across comparable workouts: as your fitness improves, decoupling shrinks.
Decoupling can also come out negative, when your Efficiency Factor is higher in the second half than the first. This usually happens with a negative split, starting conservatively and finishing faster, or when heart rate is still settling into the effort during the opening minutes, making the first half look less efficient than the second by comparison.
Advanced metrics in The Outsiders are most powerful read together. Relative Intensity tells you how hard, Variability Index how steady, Efficiency Factor how efficient, and Decoupling how well that efficiency held up, a picture no single number can give.
Putting It All Together
So that's that. Lots of numbers and charts, overwhelming at first, but very helpful once you become familiar with it. No single number tells you how a workout really went. Key Stats and Zones tell you what you did and how hard, Breakdown shows where your effort held up or dropped off, and Charts show it unfolding in real time. In The Outsiders, Relative Intensity, Variability Index, Efficiency Factor and Decoupling go further, revealing whether that effort was efficient and sustainable, not just hard. Read side by side and tracked over comparable sessions, these metrics turn a single workout into a clear decision about what to do next in training.
Frequently Asked Questions
Do I need to set my FTP or lactate threshold heart rate myself?
FTP can be calculated from your previous rides, but it's best to do a proper FTP test. The same goes for lactate threshold heart rate: it can be calculated from your heart rate zones, max and resting heart rate, but it's best to work it out from a proper test. Either way, advanced metrics are only as reliable as the threshold behind them.
Can I compare these metrics between running and cycling, or against someone else's numbers?
Not directly. Each metric is calculated differently per sport, and Efficiency Factor in particular reflects your own physiology. Compare your numbers across similar workouts over time, not against another sport or another athlete.
Why might these metrics look off for a single workout?
A short session, a brief interval, GPS or power dropouts, or an unrepresentative warm-up can all skew a single result. Treat one-off numbers with caution and look for patterns across several comparable sessions instead.
Do I need a power meter to see these metrics?
Variability Index, Efficiency Factor and Decoupling need power data for both cycling and running: a power meter on the bike, or Apple Watch Series 6 or SE or newer, with watchOS 9 or newer, to measure running power. Relative Intensity needs power for cycling too, but for running it's based on lactate threshold heart rate and average heart rate instead.
About the author
Andrej Mihelič
A co-founder, product owner and designer at Gentler Stories LLC. With 15+ years in mobile app development, he's a seasoned athlete passionate about sustainable training. Prioritises quality over quantity and intentional design without clutter, living and breathing Gentler Streak and The Outsiders.