running harder than 'plodding along' and holding that pace certainly has some training value. Thats srt of what most people try to do when 'tempo running.'
However running being what it is, you have to pay the piper when you speed up - your heart rate is higher, and you generate more wear and tear on your body. There is no clever gearing arrangement or other wheeze for getting extra speed without extra effort.
The faster you run the more impact force reverberates back form the ground into your body.
Also running is less 'efficient' than cycling so the greater 'drag' means that energy usage goes up faster with speed than it does with cycling.
plus running doesn't have gears that help you take the same power output to a faster velocity through that trick.