Pacemaker having a floating feeling

Dad has gone from heavy legs after his pacemaker was set from being at 60 for 1 year.. and was recently set to rate response..We dont get much info on how this works but dad  has a floating feeling and his heavy legs have gone.
We are not sure why he has this feeling.Could it be paced just too high or is there another problem we dont know why rate response was not turned on to begin with? He had numerous tests for heavy legs which hospital sent him for they must have known this was caused with pacer  being set at only 60. Does anyone else have this floating feeling and a feeling of loosing confidence is this caused by too much oxygen.