FitnessSyncer Compare

FitnessSyncer Compare allows you to compare two or more items from your FitnessSyncer Stream. For example, if you are training, FitnessSyncer Compare allows you to compare two workouts to see how they differ and provide you insights into what you need to focus on to improve.

You can compare any two or more items of the same kind, such as two runs, two nights of sleep, two weigh-ins, two ECG recordings, or the same day’s cycle tracking as two different services recorded it. FitnessSyncer Compare will not mix kinds, because there is nothing useful to say about a run next to a weigh-in. Conditions, medications and allergies are not comparable and are not available since it generally does not make sense.

There are two ways to start a comparison. From FitnessSyncer Stream:

From FitnessSyncer Stream, select the Compare icon.
For each item you wish to compare, select its Compare checkbox in the Key Performance Indicator (KPI) section.
Once two or more items are selected, the Compare button will be enabled. Click it to view the comparison.

Or, when you are already looking at an item, from the item itself:

Select the Compare icon on the item.
Tick the items you want to compare it against. The list holds your other items of the same kind, most recent first, from every source, and there is a search box for finding an older one.
Select Compare. The item you started from is always included, so you only pick the others.

Whatever you compare, FitnessSyncer Compare shows a column chart for every metric that kind of item records, with one bar per item, so the differences are the first thing you see. Some kinds get more than that.

Not everything an item records is a number. Where a kind of item records answers rather than measurements — a flow level, a cervical mucus quality, an ovulation test result — FitnessSyncer Compare puts them in a table instead, one row per field and one column per item, highlighting anything the items disagree on. Fields neither item recorded are still listed, because “both blank” is part of the answer when you are checking whether two services agree.

Comparing single readings

A glucose, blood pressure, oxygen, temperature, blood panel or weight reading is one number, and two numbers side by side do not tell you much on their own. FitnessSyncer Compare adds the context that makes them mean something.

Where each reading sits in your own history. Under the bars we say how many of your readings over the last 90 days each one was higher than, so you can see whether a number is unusual for you.
Whether the difference is real. Every metric moves on its own from day to day. We compare the gap between your two readings against how much that metric normally varies for you, and say plainly whether it is larger than usual or within it.
The time of day. Blood pressure, glucose and temperature all follow a daily rhythm, so a morning reading against an evening one is not quite like for like. When your two readings were taken hours apart on the clock, we say so.
What the reading sat between. Below the bars, a chart of the same measurement either side of each reading, so you can see whether a number was the top of a climb or an ordinary point on a flat line. How far either side depends on how often the measurement is taken: half a day for glucose, a fortnight for blood pressure, a year for a blood panel.
What else you recorded around it. Exercise you did and food you ate in the same 24 hours, so a reading has a possible cause beside it and not just a value.

Shaded bands behind a chart show what the numbers mean where that is well established, such as the in-range limits you set for glucose, the standard blood pressure categories, and so on. They describe the reading; they are not a diagnosis, and nothing here is a substitute for your doctor.

Some of this needs history to work from. If a measurement is new to your account, or you have only recorded it a handful of times, we leave these out rather than guess.

Comparing activities

If your activities carry a recorded track, FitnessSyncer Compare also draws line charts overlaying them: heart rate, pace, power, cadence, elevation and the rest. Choose how to line them up with the Align by selector, which sits below the bars of totals and directly above these charts:

Elapsed time: thirty minutes into one activity sits above thirty minutes into the other, whatever their lengths, and a gap appears where an activity was not recording. This is the default.
Distance: the same distance from the start sits above the same distance in the other, so on a route you repeat, the bottom of the hill lines up with the bottom of the hill however fast you went. Elevation is drawn first, on the same distance axis, so a climb explains the heart rate beside it. Offered for up to five activities, when every one recorded distance.
Lap: lap 1 over lap 1, lap 2 over lap 2, each lap stretched to the same width. Useful for interval sessions where each repetition is one lap. Offered when every activity has more than one lap.
Same time: one shared clock, for two recordings of the same session, such as a run recorded by your watch and by a chest strap. Offered only when the activities overlap in time.

Comparing a lap or a stretch

You do not have to compare whole activities. Under the selector, each activity can be narrowed to one lap, or to a stretch between two distances, such as kilometer 2 to 4 for the same climb inside two different routes. The distances start out as the whole activity, from 0 to its full length, so you only change the end you want to move. This lets you put lap 1 of today’s session beside lap 3 of Tuesday’s. Select Apply to redraw. When you narrow an activity, the bars of its totals are replaced by a table of what the chosen part holds: its duration, distance, average heart rate and average power.

Aerobic efficiency

For each activity of at least 20 minutes with heart rate and either speed or power, FitnessSyncer Compare shows two more figures:

Efficiency factor: your speed, or your power where you have a power meter, for each heartbeat. Higher means more output for the same effort.
Decoupling: how much that efficiency fell from the first half of the effort to the second. Under 5% on a long steady effort usually means a solid aerobic base.

These only mean something for a steady effort. An interval session decouples by design, so for one that varies too much we say it was not a steady effort instead of showing a number.

Two recordings of the same session

When you compare two activities recorded at the same time, such as your watch and your chest strap on the same ride, choose Same time and FitnessSyncer Compare adds a chart for each measurement both recorded, showing how far apart the two were at each moment against their average. Above each, in words: how much higher one read than the other on average, the range 95% of the differences fell in, and whether the gap grew as the value rose. It needs at least ten minutes recorded by both. When you open Compare from an activity, a recording of the same session from your other sources is listed first in the picker.

From FitnessSyncer Maps

On FitnessSyncer Maps, click the map where a route you repeat runs and the activities through that spot are ticked in the list of routes; select Compare the chosen activities to compare them by distance. You can choose up to five.

Asking your AI assistant

Your AI assistant can make the same comparisons. Connect it to the FitnessSyncer MCP server, then ask, for example, to compare your last two runs of a route by distance, or lap 1 of today’s session with lap 3 of Tuesday’s.

Compared with your other entries

Some items are worth comparing with many of your others rather than with one, so their own page does it for you, under Compared with your other entries:

A night of sleep: your deep and REM sleep over the previous 90 days, grouped by when your last workout of the day ended (no workout, before 6 PM, 6 PM to 8 PM, after 8 PM), and which group this night was in. A group is shown once it has 8 nights.
A meal: when you have eaten the same thing at least three times with a continuous glucose monitor running, your glucose after each of them on one chart lined up at the meal, with the median rise and how long it took to peak. Where you sometimes started a workout within an hour of the meal, the rise with and without one.
A workout: for a workout of a kind you have done at least three times with glucose readings around it, your glucose after each of them, lined up at the start, with the median fall and rise.
A cycle tracking entry: basal body temperature, or resting or sleeping heart rate where you do not record temperature, by cycle day across your recent cycles, day 1 over day 1. It describes the cycles you had and predicts nothing.

These show what went together; they do not show that one thing caused another. They are in the apps as well, on the same item pages.

Comparing sleep

When you compare two or more nights of sleep, FitnessSyncer Compare stacks each night’s sleep graph one above the other, using the same colours you see on the night’s own page. Reading down a column tells you what each night was doing at that point.

Because no two nights start at the same moment, you choose what to line them up on with the Align by selector above the graphs:

Sleep onset: line up the moment you actually fell asleep in each night. This is the default, and it is the one that separates went to bed late from took a while to fall asleep.
Bed time: line up the start of each night, so both graphs begin together.
Clock: put both nights on one clock. A night that began later is shown as awake until its own sleep starts, so the difference in when you went to bed is visible as that block of time.
Wake: line up the moment you woke, so the nights run backwards from a shared morning.

Click any block in a sleep graph and FitnessSyncer Compare will tell you what every night was doing at that same point, not just the one you clicked.

Below the graphs you will find a table of figures worth comparing that are not on the night’s own page, such as time awake after falling asleep, how long it took to reach REM and deep sleep, the longest unbroken stretch, awakenings per hour, and how much of the night each stage accounted for, along with your heart rate in each sleep stage, and your heart rate, HRV, respiratory rate and oxygen through the night.

Comparing ECG recordings

Comparing ECG recordings shows you three things.

Recording Data: the details of each recording side by side: classification, average rate, duration, source, sample rate, lead and any symptoms you noted. Anything the recordings disagree on is highlighted, so what differs is what stands out.
Compare Strips: the traces themselves, one above the other, each running the full length of its recording on shared clinical graph paper. A second is the same width in every strip, so reading down a column compares like with like, and the paper scrolls sideways to move through a long recording.
Source Fidelity Check: see below.

ECG comparison takes between two and four recordings at a time. Long recordings are supported, but the strips show their first five minutes; open a recording’s own page to read all of it.

If you compare two recordings of what appears to be the same heartbeat received from two different services perhaps taken within a couple of seconds of each other or from different sources, FitnessSyncer Compare adds a Source Fidelity Check: the difference in sample rate, in signal amplitude, and in timing between them. This answers “did both services give me the same recording?”, which is a question about your services, not about your heart. It is not a clinical comparison, and nothing in FitnessSyncer Compare is.

If Compare will not open

Select at least two items. There is nothing to compare with one.
Select items of one kind. A run and a night of sleep cannot be compared to each other.
For ECG, select no more than four recordings.

FitnessSyncer Compare is available on FitnessSyncer.com, in FitnessSyncer for iOS and in FitnessSyncer for Android. In the apps, open an item from FitnessSyncer Stream and select the Compare icon; the Stream’s own multi-select comparison is on the website only. Choosing a lap is in the latest versions of the apps; a stretch by distance is on the website only.