On the details and the splits page (tab) of a running activity you cannot choose an 'average speed' column (No 'miles per hour' or 'km per hour').
I know so many people who are really missing this option. Please give us the option to add 'average speed' as a column for lap/split details.
(when the activity is cycling you do get this option). A lot of people are training with 'speed' instead of 'tempo/pace' instructions nowadays.