What are the best ways to avoid fatigue in a workout? I will feel great one moment and completely slump with the next set. I dont really want to call it fatigue as it occurs during the lift but I wont feel any burn and cant continue with another rep. How can I stop this? it really is interfering with progress as I cant bang out those last 3 necessary reps. Dropping the weight doesnt really seem to help as it gets too light for anything but endurance training.

Another problem is that tension will build mid set in my hands to the point that it feels like my knuckles are on fire, i try to fight through it but the pain is terrible, however its gone when the weights gone. I dont know if this is normal.