Dr Kogelnig: Scientific studies comparing indoor and outdoor activities have concluded that the difference between running outdoors and running on a treadmill is minor. However, this is based only on biomechanical and biophysical factors such as tendon, muscle and bone stress, and movement sequences. Although the surface conditions are different, there is no significant difference between the biomechanics of running indoors or outdoors. However, it must be noted that the experiential value of exercising in the fresh air, and above all being surrounded by nature, has a unique quality. Visual, acoustic, olfactory and haptic perception – what we see, hear, smell and feel in natural environments – has extremely beneficial effects on how we feel, both physically and psychologically, that cannot be entirely replicated indoors.