I have been using Hornet Juice before my training sessions that are preparing me to run in the Great Ocean road marathon in Victoria, Australia on May 20.  I have noticed an improvement in my endurance in my speed training and my long runs.  I have been able to push my long runs out over 3 hours and finish strongly, which has also aided in my recovery for my next session.  The true test will be on May 20 when i line up for the 45 kilometres of pain that is the Great Ocean road marathon where i will be attempting to run under 3 hrs for the marathon distance and then finish the full 45 km strongly.