This is the elevation diagram produced by Strava, a phone app, that can record physical activity such as running, cycling, skiing and swimming.

• What do you think I was doing?
• What can you deduce about my activity from the graph?
• Can you work out the missing numbers?
• What else can you work out (for example, how far did I go)?

The graph of elevation is symmetrical, so whatever I did in the second half of the activity was the same as the first but in reverse (maybe I cycled from home, turned round and cycled back again).

The 9 peaks in the middle look very similar. Maybe I was going up and down the same bit of hill as part of a training programme.

The ‘Elevation Gain’ is the total of the uphill sections (Strava doesn’t subtract the downhill parts). I found this difficult to calculate. The 9 peaks in the middle look about 12m each. Then add the final long climb and the small upward section at the start. Strava says 167m.

The ‘Max Elevation’ is 69m above sea-level.

The total distance travelled was just over 10km. (Strava says 10.49km)

Here is an additional image from Strava:

I travelled 10.49km in 45mins and 36 seconds, which suggests a running speed rather than cycling. Clearly it can’t be swimming (uphill?) and I gather it’s difficult to ski uphill, so you might guess (correctly!) that I was doing some training where I ran up and down the same hill multiple times.

This graph doesn’t tell us anything about my speed for different sections of the run, but we can work out my average pace and average speed.

Average pace is the number of minutes & seconds per km. We need to be careful with multiplying or dividing times because the number of seconds isn’t a decimal. Converting the time into seconds gives 45 x 60 + 36 = 2736 seconds. Dividing this by 10.49 km gives 260.8 seconds, which is about 4 mins 21 seconds.

The speed is the reciprocal of this, but we need to be careful with the units: 13.8km/hour.

Here is a final image from Strava, showing some answers: