Physio Guru

This app provide some default rehab programs for common injuries to perform if agreed by your physiotherapist or medical doctor.
It allows you to create your own programs. It keeps the counter in seconds and number of repetitions.
You can use all the features of this app for free, for first five days. After that you'd need to subscribe either monthly or annually.

Privacy Policy and Terms of Service - https://tessservices.com.au/physio-guru/privacy-policy.html
Terms of use - https://www.apple.com/legal/internet-services/itunes/dev/stdeula/