Treatment: The best way to treat increased tone in the popliteus is through direct hands-on massage and ischaemic pressure. The popliteus is a very difficult muscle to stretch and will respond a lot better to hands-on treatment.
Direct massage is best done with the knee slightly flexed, as mentioned above. The bulk of the muscle belly lies in the postero-medial part of the knee under the medial gastrocnemius. Flush massage from medial to lateral tends to work best.
Direct pressure therapy is also best done with the knee slightly flexed. This will feel very uncomfortable to the patient and the therapist must be very wary of excessive pressure in the popliteal fossa, as some important nerves and blood vessels course through and down between gastrocnemius.
The above was taken from a web page (I'm not able to post links yet).