How
much rest ? 
The
amount of rest to take between exercises is as
fundamental a concern as any other, but for some
reason it is the one issue that is often
overlooked. For example, most gym veterans
can tell you how much weight they use and how
many reps they do for any exercise, but few pay
much attention to how much rest they take
between sets.
From
a physiological point of view, there's no reason
to take more than three minutes between sets.
By that time, your ATP (remember, ATP is your
body's source of immediate energy) is about 99
percent replenished and your body is as ready as
it's going to be. From a practical point
of view, there's no reason for a beginning
lifter to wait that long between sets. Two
minutes allow your muscle ample time to recover
and gives a workout partner time to change the
weight and do a set, without wasting undue time.
While
we don't want to make working out into a
stressful bit of time management, you should be
aware that when you're not thinking about time,
two minutes flies by, in fact, very often people
have brief chats between sets and they assume
it's only a few minutes. Before you know
it, the workout that should take you 45 minutes
to an hour has stretched to 1.5 hours. As
a result, it's good to time yourself between
sets early on. Once you find a rhythm,
your body will know the appropriate amount of
rest to take.
