This article is from the Fitness FAQ, by Jeff Gleixner (glex@cray.com) with numerous contributions by others.
Cycling is where you cycle the training of your muscles to keep
them growing. You train them for a certain period then switch
or rest. Here are two common ways to use periodization:
10-rep cycle: I'm not sure of the "official" name I just
tagged it with this title. When performing this type of cycle you
never do more than 10-reps per set, and only 2 work sets. To
start, you need to know your 10-rep/MAX weight for the exercises
you're going to perform. That is at what weight do you hit positive
failure at around the 10th rep. Write this weight down and figure
out 80%, 90%, 95% of that weight, for each exercise. To begin the
cycle start out at doing only 80% of your maximum 10-rep weight
for 10-reps. This should be a very easy work out. At the next
work out use 90%, then 95%, then 100% at your fourth work out, which
should be about 3-4 weeks after the cycle is started. If you
work out more than once per week then gradually add weight during
the week, keeping pace with the above outline. When you hit your
previous 100% weight you should be able to add a little more weight
at next week's work out. Keep adding a small amount of weight, 1-2
lbs, per work out until you can't do 10-reps for 2 weeks in a row.
When that happens your muscles are no longer getting stronger. Take a
week off. Then start at 80% of your new max.
Week 1: 1x10 light 1x10 medium 2x10@80% of 10-rep max Week 2: 1x10 light 1x10 medium 2x10@90% of 10-rep max Week 3: 1x10 light 1x10 medium 2x10@95% of 10-rep max Week 4: 1x10 light 1x10 medium 2x10@100% of 10-rep max Week 5-?: 1x10 light 1x10 medium 2x10@100%+ of previous 1-rep max.
Weeks 1-4: 1x10 light 1x10 medium 3x10 heavy (target weight)
Weeks 5-8: 1x10 light 1x5 medium 3x5 heavy (target weight) 1x10@70% of target
Weeks 9-10: 1x10 light 1x3 medium 1x3 medium-heavy 3x3 heavy (target weight) 1x10@70% of target
 
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