circuits for beginners?

You can start with the NerdFitness beginner's bodyweight workout: http://www.nerdfitness.com/blog/2009/12/09/beginner-body-weight-workout-burn-fat-build-muscle/

In my experience, weight lifting should be an integral part of any fitness routine — but I understand not everyone can afford a monthly gym membership. With that in mind...

1. Get a pair of 7.5, 10, 15 or 20lbs kettlebells, depending on your gender, strength and level of fitness. They can be had for fairly cheap and there are a million different kettlebell exercises to target every muscle group in the body in seventeen different ways. They're a worthwhile investment! Go as heavy as you can swing it — you'll get used to the weight before you know it.

2. Each workout session, pick four exercises from this list, depending on the muscle groups you want to target. If you don't know a particular exercise, google the name — plenty of detailed videos on youtube:

Bodyweight exercises:
- Push-ups.
- Burpees.
- Crunches (not sit-ups — google the difference.)
- Leg raises.
- Planks (go for time, say, 60 seconds per set.)
- Planks-to-push-ups (go for reps.)
- Mountain climbers.
- Pull-ups (if you have a pull-up bar available.)

Kettlebell exercises:
- Kettlebell Russian twists.
- Kettlebell swings.
- Weighted lunges.
- Front squats.
- Goblet squats.
- Sumo deadlifts.
- High pulls.
- Alternating curls.
- Curl-to-press.
- Push press.
- Alternating press.
- Arnold press.
- Floor press.
- Flys.
- Kettlebell kickbacks.
- Kettlebell bent-over row.
- Renegade row.

This list is not at all exhaustive, but its enough to keep you busy for a long time before you get bored. When you do get bored, google can help you find more KB and/or BW exercises to try in your circuits.

3. Do one set of each of the four exercises you picked. Once you've done a round of all four exercises, start over until you've done four rounds. Don't rest between exercises or rounds — the point should be to get your heart going as well as your muscles.

As for number of repetitions per set, I like to do a descending circuit one week, and then a steady pace the next, slowly upping my reps each week. Something like this:

Week 1: 12-10-10-8
Week 2: 12-12-12-12
Week 3: 15-12-12-10
Week 4: 15-15-15-15
Week 5: 17-15-15-12
Week 6: 17-17-17-17
Week 7: 20-17-17-15
Week 8: 20-20-20-20
Week 9: 23-20-20-17
Week 10: 23-23-23-23
And so on...

Once you start getting to a 30-30-30-30 set or so, you can add a fifth round to your circuit. And when you get used to that, add a fifth exercise, as well. I stopped changing things at a 40-35-30-25-20 circuit of 5 exercises.

So, for example, let's say on Week 1 you pick burpees, KB swings, leg raises and alt curls. Your workout would look like this:

Round 1:
- 12 burpees.
- 12 KB swings.
- 12 leg raises.
- 12 alt curls.
Round 2:
- 10 burpees.
- 10 KB swings.
- 10 leg raises.
- 10 alt curls.
Round 3:
- 10 burpees.
- 10 KB swings.
- 10 leg raises.
- 10 alt curls.
Round 4:
- 8 burpees.
- 8 KB swings.
- 8 leg raises.
- 8 alt curls.

Then on week 2 you pick mountain climbers, floor press, flys and kickbacks. Since week 2 is a fixed reps week, every round would look like this:

Rounds 1, 2, 3 & 4:
- 12 mountain climbers.
- 12 floor press.
- 12 flys.
- 12 kickbacks.

It should take you between 5 and 20 minutes to finish a circuit, depending on how many exercises, reps and rounds you're doing. You can then finish off each session with some straight cardio work (jogging, bicycling, swimming, going up and down stairs, etc.) Do as much as you need so that your total workout time is 45-60 minutes — e.g., if your circuit took 12 minutes, run intervals for 33-48 minutes.

Sorry for the long post. Hope it helps!

You can start with the NerdFitness beginner's bodyweight workout: http://www.nerdfitness.com/blog/2009/12/09/beginner-body-weight-workout-burn-fat-build-muscle/

I was about to suggest the same thing. Jefit.com has some good ones as well.