Updated: Nov 14, 2020
A Complex is a circuit
The difference is you use the same piece of kit the whole way through a complex, there's no rest as you go form one exercise to the next.
Kettlebells make a great tool for complexes.
Complexes make a great tool for getting people disgustingly well conditioned.
This is why they've been a staple of Combat Sports practitioners for ever!
Here's our Seb, WG-Fit coach, Nutritionist, BJJ Black Belt and more showing one of his favourite complexes:
After a good warm up he's set his timer for 20 minutes.
Then he grabs a pair of kettlebells and rips through:
See Saw Press
Bent Over Row
Each exercise is done for 6-8 reps. Rest periods between each round of the complex is up to you, the heavier the weight you choose, the longer you'll rest. The lighter bells, you won't rest, so you can decide where on the Strength-Endurance continuum you want to work. That said, the best guideline for selecting a weight I ever got for complexes is:
"If you're not crying for your Mum towards the end of the second round, it's too light!"
You have 20 minutes to get in as many rounds as possible.
If you have a sandbag or barbell, this works just as well, you'll just have to adjust the exercises to suit, work a standard press instead of See-Saw, and RDL's / High Pulls or Cleans instead of Swings.
Either way, have fun and work hard! Regards