Muscles worked
This is the overhead triceps extension with a loaded backpack instead of a dumbbell. Your triceps do the work, and the overhead position stretches the long head at the bottom. A backpack is wider and softer than a dumbbell and its contents can shift, so your hands and forearms work harder on the grip.
Common mistakes
- The contents slide around. Loose items move on every rep and make the weight jerky. Pack tightly with books or water bottles, fill the gaps with a towel, close every pocket and check that the seams and zips will hold.
- Holding the carry loop. A bag hanging from the small loop swings behind your head and is hard to control. Grip the bag itself with both hands, ideally around the bottom or the sides.
- The bag hits your neck. A big bag can knock into your neck or upper back. Pack it compactly and lower it slowly, only as far as it goes without touching.
Variations and alternatives
- The overhead triceps extension is the same movement with a dumbbell, when you have access to weights.
- The band overhead extension uses a band, which is easy to take with you.
- Bench dips train your triceps at home with only a chair or a bench.
- The backpack shoulder press uses the same backpack for your shoulders, if you want a whole session built around the bag.
Sets and reps
Log the bag's weight, read off a bathroom scale, so your sessions can be compared. For muscle, 12 to 20 reps over 2 to 3 sets works well, and since the load is often light, it pays to go close to failure. The guide to reps in reserve explains how close, and the basics are in the guide to sets and reps.
Pack in another book or bottle until the bag gets too bulky to hold overhead. After that, pause for a moment with the bag behind your head before straightening your arms, which makes the same load harder. Both are progressive overload. Pain in your elbows or shoulders, rather than plain effort, means you should stop the exercise and have a doctor or physiotherapist look at it.