I am more confused than ever after searching for information on lactic acid. In the past I have done Jari Love's Get Ripped workout which uses very high reps and lower weight and always feel the "burn" which I understand is the lactic acid but I am not sure if I had ever really felt muscle fatigue. Could I have mistaken the burn for muscle fatigue? Is it a good thing or not to feel the lactic acid and the burn? Do you only feel the burn from doing high reps? I am used to doing 60+ reps with that workout and am now thinking maybe that is why I didn't get great results is because I was only feeling the burn and not really fatiguing my muscle?? Sorry for the questions, I am still trying to figure out the fastest and BEST way to achieve the results I want

High reps with lower weight can lead to muscle fatigue; moving the muscle so many times, even lightly, can tire it out. The 'burn' you feel is probably lactic acid; muscle fatigue is when you can't move the muscle for one more rep.

Not sure of what results you are looking for, but high reps/low weights will not build muscle. It can lead to muscle toning, but that is more a function of losing fat, not building muscle. To build muscle and really, really feel the fatigue, you must lift heavy with fewer reps.

The fastest and best way to achieve your goals is by lifting in the 8 to 15 range. Maybe even 6 to 12. Over 15 is generally said to be pointless and I happen to agree with that. You can wave your arm around for half an hour and feel plenty of burn...won't do much for your body though!

I'm not sure what your goals are but even if it's not to build much muscle you'll want to lift heavier and for less reps.

"Tone" is building some muscle and burning off the fat so that you can see it.
60 reps at once is cardio with the added potential for tendonitis due to repetitive motion. Try three sets of 12 at a weight where rep12 is HARD.

Mel