To calculate the average speed of the runner, you can use the formula:
\[ \text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} \]
In this case, the total distance is 32 kilometers and the total time is 4 hours.
Plugging in the values:
\[ \text{Average Speed} = \frac{32 \text{ km}}{4 \text{ hours}} = 8 \text{ km/h} \]
Therefore, the runner's average speed is 8 kilometers per hour (km/h).