In a study of the effectiveness of dry needling for hamstring injuries in runners, participants attending a physiotherapy clinic with new hamstring injuries were randomised to dry needling plus usual care versus usual care only. Here treatment is a binary variable ( = 1 indicates received dry needling, = 0 did not receive dry needling ) . After the physiotherapy session all runners were given an exercise schedule. is a binary variable indicating whether the runner did the recommended exercises ( = 1 ) versus did not do the recommended exercises ( = 0 ) . It is thought that dry needling could have an effect on whether the runners did the prescribed exercises. The outcome is a binary variable indicating full return to running within 5 weeks ( = 1 ) versus still having hamstring problems preventing training 5 weeks post the treatment session ( = 0 ) . The variables , and were recorded for each runner.

The initial assumption is that there is no confounding of the exercise - recovery relationship. Draw the DAG from the study description. Do you believe the assumption of no confounding of the exerciserecovery relationship is plausible and why / why not?