It took me 26 years to figure it out, but I've just realized that I enjoy sprinting more than jogging :D .

Kidding aside, I'd really like to improve my speed and quickness. Running has always been a favorite exercise of mine, but due to an IT band injury and my current goals, I don't think distance running is an option any more. I have been doing some HIIT and fartlek, but I still have some questions on interval and speed exercises:

First, will HIIT negatively affect my overall stamina? I understand that a lack of distance running will cause me to lose some endurance, but will speed exercises hurt me even more? Will I be huffing and puffing after a couple minutes on the basketball court?

Second, I've been told that speed training cannot be substituted for endurance training as far as cardio is concerned. Apparently, speed training is good for fat-burning, but it won't help your heart out. Is this true?

Lastly, aside from HIIT and Fartlek, do you have any other suggestions for speed training?

Thanks much!

Sprints will not affect stamina adversely unless you stop all endurance training altogether. It still works the heart and lungs, but it's training a different kind of muscle fiber than running does (fast twitch vs. slow twitch) so unless you're training both ways, your overall endurance will suffer eventually. HIIT is still more 'endurance' than sprints alone, so if you do 20-30 minutes of HIIT, it really counts for both. And it is good for your heart. Check your pulse after a sprint session sometime. ;) Since you're using intervals, you *are* keeping heart rate high for a relatively long period of time.

To increase speed you need to increase resistance. If you are on a treadmill, increase the incline while sprinting. If you're road running, use a backpack/fannypack and add some weight. Then when you have that resistance removed, your explosive power will be increased from training with that added resistance.

Thanks for the reply, Naxis. Do you think it's a bad idea to run HIIT the day after/before resistance training on legs?

Not a good idea to do leg exercise and HIIT on consecutive days since they're both basically resistance training. Kind of like two leg workouts back to back. Not *necessarily* bad, but the latter session will probably suffer due to lack of proper recovery time. Legs tends to need a little extra recovery time anyway.