Your Average
Compare Against. Every ▲ ▼ arrow, Effort, Load and "usually" figure compares a game with the games played before it: your last 10, 20 or 50, or all of them. Choose with the "vs" picker under the stats (or in Settings). Drop-ins are left out of the average. Until there are enough earlier games (3 for arrows, 5 for Effort and Load) those stay blank.
Arrows. ▲ more than 2% above your average, ▼ more than 2% below, – within 2%. Shifts, time on ice and calories are compared per minute of session, so a short session isn't marked down just for being short.
Shifts and Ice Time
Shifts. Your strap or watch records heart rate, not where you are, so shifts are found from it. A shift starts where heart rate begins a sustained climb and ends at the peak before it falls. To count, a climb must last at least 40 seconds, rise at least 15 bpm and peak above 75% of your max heart rate. Dips under 30 seconds, like a whistle, stay inside the shift. Heart rate lags the play by about 10–20 seconds, so each start and end can be off by about that much.
Warm-up. Shown in gray at the start of the heart-rate chart. Warm-up and shifts look different: in warm-up your heart rate climbs slowly to a plateau, then eases off while you wait for puck drop; your first real shift jumps fast (25+ bpm within about a minute) to near your usual shift peak. The warm-up runs from when your heart rate lifts off resting to where that plateau breaks. Anything in it is left out of shifts, time on ice, shift lengths, rest and shift peaks; it still counts toward duration, heart rate, zones and calories. Games recorded with the Line Change watch app say whether there was a warm-up, so it's only looked for when there was one. If a game is off, use ⋯ → Edit Warm-Up to move it.
Time on Ice (TOI) is the total length of your detected shifts. Avg Shift is TOI divided by shifts. Drill-heavy practices without clear bench breaks are detected less reliably than games.
Heart-rate chart. Your heart rate every 5 seconds, smoothed slightly. The orange bands are the detected shifts. Hatched stretches are where the strap lost contact for 15 seconds or more; nothing is drawn there, and a note says how long it was. Shifts can't be found in those stretches, so that game's shifts, time on ice and distance may read a little low.
Est. Distance and Strides are estimates; there is no GPS or motion data. Each shift is given a skating speed from how hard your heart worked (about 160–280 m/min, harder shifts faster) and multiplied by its length. Strides use about 3 m per stride. Expect them to be within roughly ±20%: good for comparing your own games, rough as an absolute number. Per shift is distance divided by shifts.
The Session
Duration is the full recording, warm-up to stop. Avg HR and Max HR are over that whole recording.
Calories are kilocalories (kcal), the same unit as food labels; Metric shows kilojoules (1 kcal = 4.184 kJ). They are the number your device reported (Polar, Apple Watch and so on), so they match that app. If it gives none, Line Change estimates them from heart rate with the Keytel equation, your age and your profile weight.
60-Sec HR Recovery is a heart-rate number, not a time: how far your heart rate falls in the 60 seconds after a shift ends, averaged over your shifts. A peak of 180 that is 150 a minute later is a 30 bpm recovery. A faster drop usually means better aerobic fitness. Wrist devices that record heart rate less often are left out of this one.
Max Heart Rate comes from your profile. Left blank, it starts at 220 minus your age and rises to the highest heart rate seen in your games. It sets your zones and the 75% shift threshold.
Performance
Effort is how hard you pushed regardless of ice time: heart-rate intensity per minute, share of ice time above 90% of max, and how high your shift peaks got, each against your average. Load is total work: minutes in each heart-rate zone weighted by how hard the zone is (zone 1 counts 1, zone 5 counts 5). Both are out of 10, where 5.0 (the tick) is a normal night for you.
Ring colour follows the score: green 5.5 or more (harder or more work than usual), yellow 4.5–5.4 (normal), orange 3.5–4.4 (lighter), red under 3.5 (much lighter). Red means a light night, not a bad one.
% vs Norm is this game's intensity per minute (Effort) or total load (Load) against your average, as a percentage.
The sentence under the rings sets the scores against the game: a game the night before, an unusual league, a drop-in, bench size, session length and time above 90%.
What Drove Effort shows the three parts of Effort for this game, each bar with your average as the tick: intensity per minute, time above 90% of max HR, and average shift peak.
Effort, Recent Games is your Effort score for this game and the nine before it.
Readiness uses the recovery time your device suggested after this game (Polar today). The bar fills from when the game ended. Under 35% of the way: rest. 35–70%: a light skate or easy lift. 70–100%: a full skate or a normal lift. 100%: fully recovered. It's a rule of thumb, not medical advice, and it's hidden when the device gives no recovery time.
Heart rate also moves with sleep, illness, heat and caffeine, so treat a low score as a prompt, not a verdict.
Metrics
Shift by Shift. Bar height is shift length. Bar colour is the shift's peak heart rate as a share of your max, from blue (under 75%) to red (95% and up).
Longest Shift is your longest shift and how many times your average shift it ran; the bar's tick marks your average shift that game. Hardest Shift is the shift with the highest peak heart rate, as a share of your max; the dot sits on the same blue-to-red scale as Shift by Shift (75% to 95%+ of max). Work : Rest is time on ice against time on the bench between shifts; 1 : 2.0 means two minutes of rest per minute played. The bar is the share of that time spent on the ice.
Time in Each Heart-Rate Zone. Minutes spent at 50–60%, 60–70%, 70–80%, 80–90% and 90%+ of your max heart rate, over the whole session.
Early vs Late Game compares the first third of the session with the last third: average 60-sec recovery and average shift peak. A smaller recovery late in the game usually means fatigue.
Splits, Trends and History
Splits compare your average game in two or more groups. Bench Size estimates lines from bench time per minute on ice (about 2, 3, or 4+ lines). Back-to-Back is a game the day after another session. Time of Day: Midday starts 9 AM–3 PM, otherwise Evening. Game Length: under 80, 80–100, over 100 minutes. The headline is the stat with the biggest gap. Groups under 5 games are faded: treat them as a first look.
Trends average each season (August to July) and compare this season with your average across all seasons.
History lists every session with its time on ice and Effort score.
Games and Drop-Ins. A session that starts 9 AM–3 PM and runs 115 minutes or longer is treated as a drop-in; everything else is a game. Averages, trends and arrows use games only.
Not measured. Speed, glide and exact distance need motion sensors these recordings don't include. VO2max can't be measured from game heart rate.