Workout duration

I Work as a running and cycling instructor, and host classes of 1-2 hours 3 times a week. As i am allready in the gym and it takes me 30 min to travel each way i like to get my strength workout in afterwords, usually lasts about 1-2 more hours. Problem with this is that after the cardio i feel somewhat fatigued, and i don't have as much energy left as i could have had. 

 

I am conserned how much it will take away from my progress strengthwise to have such a long workout, i also read this article (link) that talked about testosterone lvl decreesing during long workouts. Any truth in this?

http://jasonferruggia.com/how-long-should-your-workout-last/

 

Would it be recomended to eat, like a protein shake or something in between, or is it fine just eating before the workout?

 

Also i would be interested in general thoughts on long workouts, both benefits and challanges!

 

 

You could try get the strength training done before the cardio, rather than after. 

Eating something small inbetween workouts for extra energy and strength would be better than waiting.

 

Two fairly ripe bananas or a protein bar would be plenty.

I don't really have the time to get the strength done before, so thats not really an option. I tried to eat between, diddent really notice any differense in the way i felt, but might still be a good thing to fuel the muscles a little! thanks for tips