If you need to scale the width or height of an image without distorting the subjects, try using the Content-Aware Scale (Edit > Content-Aware Scale).
If the scale still distorts your subject, create a selection in the shape of your subject and save it as a channel. Then in the options bar, while you’re re-doing the scale, click on the “protect” drop-down and choose the channel you created. The distort will now only affect everything not selected by the channel.