The pressure sensor doesn't produce a voltage, it only changes its resistance. You have to add another resistor, to form an voltage divider (half bridge). Connect the sensor end to Gnd, the resistor end to Vcc, and the junction to the analog input.
You'll have to experiment a bit, which resistor to use for each sensor. When you use a resistor equal to the pressed sensor resistance, the measured voltage will be 2.5V (Vcc/2), i.e. analogRead() will return about 512 when the sensor is pressed.