Open one split and see what happened in it

The splits table shows you which kilometre was slow. This screen is for why. Tap a row — in Splits, in 5K Splits, or under Segments if your watch recorded laps — and that one stretch gets a page of its own.

The lines at the top

#

The rows read top to bottom in the order you’d ask about them:

• Duration and Distance — how long that split took (e.g. 05:54) and where in the run you were when it ended (1.000 km), so you don’t have to count rows.
• Avg. Pace and Maximum Pace — the average is the row you tapped; the maximum is the fastest moment inside it. A big gap between the two means the kilometre wasn’t run at one speed.
• Avg. Grade Adjusted Pace — the same kilometre as if it were flat. When it’s faster than the pace above it, the hill is the reason. There’s a whole page on reading that difference.
• Heart rate and intensity — average and maximum for the split, then the same two as a percentage of your Max HR.
• Elevation Ascend and Descend — the climb and descent inside one kilometre, separately. This is the most common answer to “why was this split slow”. Twenty seconds off your average with 30 m of ascent in it wasn’t a bad kilometre.
• Steps, Cadence and Stride Length — split-specific step count, cadence in spm, and average stride length. Cadence holding while stride shortens on a climb is normal; both dropping is the telltale sign of fatigue.
• Ground Time and Vertical Osc. — your average ground contact time (in ms) and vertical bounce (in cm) for this stretch alone. A sudden jump in ground contact time or vertical oscillation points straight to form degradation.

Two more rows appear with Pro: Pace Stability Index and Efficiency Factor, worked out for this split rather than the whole run. They’re the ones to check when a run scored low on stability and you want to know which kilometre broke the rhythm.

Performance and Running Form charts

#

Right beneath the metric rows, a segmented toggle switches between two complementary views for the split:

[ 📈 Performance | 🏃 Running Form ]

The Performance view

#

On the run page a single kilometre is compressed into a narrow sliver; here it fills the entire width.

• Pace and Heart Rate each get a chart zoomed strictly to the split’s start and end. Touch anywhere on a chart to scrub along the trace with your finger and inspect the exact pace or heart rate at that moment.
• Running Power shows your split average wattage (e.g. Avg: 153 W) and range (Range: 74–168 W), giving you instant feedback on your mechanical output.
• Elevation backdrop: drawn in soft grey behind each curve. Most of the time that’s all you need: the pace line dips exactly where the grey contour rises, and the question answers itself.

The Running Form view

#

When a kilometre felt unusually heavy or sluggish, switching to Running Form reveals whether your biomechanics held together:

• Flight Trajectory arc: visualizes your split stride length (0.97 m), vertical oscillation (8.4 cm), and split Vertical Ratio (8.7%). You can immediately see whether your energy went into propelling you forward or bouncing upward.
• Gait Cycle Timing bar: breaks down this split’s single step cycle into Ground Contact Time (259 ms, 76%) and Flight Phase (84 ms, 24%), alongside split Duty Factor (37.8%).
• Cadence and dynamics charts: zoomed time-series charts showing your cadence, ground contact time, and vertical bounce across the split.

Comparing the Performance and Running Form views tells you the whole story: whether a slower kilometre was an intentional breather with clean form, or a struggle where contact time lengthened and stride collapsed.

Worth knowing

#

• Everything on this screen is free except the two Pro rows. It works on every run already in Apple Health, however old.
• A treadmill split has no elevation rows, no GAP and no elevation chart — there’s no route to take them from. Pace, heart rate, cadence and stride are all still there.
• A very short split has no charts. Anything under a minute — usually the last few hundred metres of a run — shows the rows only; there isn’t enough of a line to draw.
• Intensity uses the Max HR in your settings. If it looks wrong on every split, the fix is in your zones, not the run.
• Don’t read the first split too hard. GPS settles over the first few hundred metres, so kilometre one has the least trustworthy pace and elevation in the run.