I dont see how legs would require to be barefooted. A persons muscles could still be empowered by a parasite. This still applies for legs. Thus, allowing a person to run quickly.
As for the chest. The heart or lungs would be the ones which are affected, both would allow respiration to happen at a quicker rate therefore increasing endurance. Saying mobility was a fault of mine.
We see Migi travel upwards of Sinichi's hand when he enters at his wrist. Judging how every parasytes main target is the brain we can infer he was trying to reach there before he got stuck, but since the distance from the eye to the brain is shorter. I can say with confidence being attacked at the eye would lead to a full takeover.