This is best exercise I have found to increase the strength and endurance of your hands and fingers.

EDIT: To clarify, I am not saying that one should increase their hand strength so they can play harder. To everyone saying that it is better to relax your hand and use a lighter touch, not only am I in complete agreement with you, but the advice I'm suggesting is supposed to help you have a lighter touch.

If you are trying to improve the efficiency and economy of motion in your technique, there are two areas to improve upon:
1) Psychological/Nervous System - Relaxing your mind increasing your motor control and finger independence
2) Physiological - Correcting your posture and increasing the strength and size of your forearms/hands, back, core, etc so that it takes less energy to perform the motions associated with playing your instrument.

Not everyone needs to strengthen their hands. You don't *need* strong hands to play bass. All I meant to imply in my original post is that if for whatever reason you would like to make your hands stronger, the best way I have found to do this is by performing a proper deadlift as demonstrated here:

.

---------------------------------------------------------------------------------

Deadlifts. Plain and simple. I've tried stretches, fingering exercises, those gripper things, stress balls, you name it. Nothing has made my hands (aka FOREARMS) stronger than putting weight on a bar and picking it up off the ground.

I decided to start lifting weights for completely unrelated reasons, but I was shocked to find out how light the strings and neck of my bass felt the day after doing deadlifts. Not to mention the benefits a proper deadlift gives to your back and posture, which directly translate into your playing.

Just to be clear, as a musician you should always stretch your hands before and after you play, and running through various scales, finger exercises, and even guitarist grippers are a great way to strengthen your nervous system and improve finger independence, flexibility, etc.

But if your goal is to make your hands / grip physically stronger, I highly recommend throwing that stress ball away, getting a gym membership and lifting some weight.

Couple of edits:

1) Deadlifting and weight training can be dangerous when performed without proper technique, but when performed correctly weight-training is perfectly safe and accessible to all ages and body-types.

2) I am not implying that one should increase their hand strength so that they can play harder. Rather I would say that one of the main reasons people play so hard is because their hands are weak and they are over compensating. It is much easier to play with a lighter touch when your hands and forearms are strong.

 

Absolutely! I live in an apartment and I don't exactly have the space for a bench or power-rack. It's definitely a goal of mine to create a little home gym in the next place I live though. I would love to have a yard so I could get a tractor tire and some sandbags of varying weights and work on some functional strength traning.

 

So I absolutely agree that proper form is the most important thing in weight training, however I have to disagree with the notions that deadlifting and weight training are inherently dangerous and that not being able to perform a correct deadlift is a good reason to avoid the exercise. I would argue the person who can't deadlift correctly is the person that needs to the most. In fact, corrective deadlifting (i.e. low weight with a strict emphasis on form) is one of the best ways to help lower back problems and correct posture. You're right, though. If you have never lifted weights before, or if it has been years, you can injure yourself by lifting too much weight or lifting incorrectly. I don't like framing that in a way that would discourage people from exercising, though. Unless you have an injury or disability, deadlifting and weight training are perfectly safe exercises when performed properly and have tremendous health benefits. You do not have to use a full-size bar and weight plates to perform the basic exercise. You can start out with simple dumbbells or even just your own body weight.

 

That second video is seriously amazing. Who is this guy? What is the context?

 

Yup, rock climbing is amazing for forearm strength. I hope my post didn't come off as implying that hand strength is more important than finger dexterity and independence. And don't knock it til you try it - I totally get what you're saying about relaxing your hand and not exerting so much effort into your playing. I'm saying that it's much easier to do that when your forearms are stronger. The next time you go rock climbing try and remember to play your bass the next day and note how much easier it is to play with a lighter touch.