Alcohol is a diuretic, which means incessant peeing, and an increased chance of dehydration.
Another issue is that alcohol is a diuretic and being dehydrated will certainly interfere with your speed and endurance.
diuretic di·u·ret·ic (dī'ə-rět'ĭk)
Tending to increase the discharge of urine. n.
A substance or drug that tends to increase the discharge of urine.
A substance that increases the rate of urine production.