You can synchronise the activity of Runtastic through Google Fit: 


How to connect Runtastic with Google Fit: 


When you complete an activity with the Runtastic app and sync it to Runtastic.com, Google Fit will also receive the activity data and then display information such as start time, duration, distance covered and calories burned. This information then forms part of your daily activity stats in Google Fit.

Steps:


1-  Make sure you sign into Runtastic with your Google+ account, or sign in and link your Google+ account to your Runtastic account on Runtastic.com. 2- Then, in the Runtastic app, go to ‘Settings’ 

3 - Go to ‘Partner Accounts’ and click ‘Connect’ next to Google Fit.


Once you have linked Runtastic and Google Fit , you simply have to add Apple Health in your WeFitter connections as indicated here.