there is no accepted age cut off for a speed work out. This should be based on the individual and their current physical status, to ensure maximum safety. I would say the older they get the less likely to do it though.
it would fall at a lighter speed
No. If you cut down on carbs you may not have enough energy to do a proper workout. Consuming proper amounts of carbohydrates can help you have enough energy to workout properly.
Cut the exercise portion short.
No, but it could effect how the transmission shifts.
it would become longer
No, there is no cut-off age.
8
two
two
two
Mostly with caffeine.
Faults are always younger than the rocks they cut. They cannot be older that the rocks they are cutting, because the rocks would not be there.