Question: I'm currently playing a piece which requires big stretches of large intervals across the keyboard. It slightly hurts when I do so, and I am wondering if I should continue to practise like this.

[![Bartok Suite op14 - Allegretto](https://i.stack.imgur.com/6cfvl.png)](https://i.stack.imgur.com/6cfvl.png)

My piano teacher suggests fingerings with a combination of 3 1 and 2 1 in the L.H.

Answer: 
In my piano lessons I was told the story in which famous composer Schumann permanently damaged his fingers by performing excessive stretching exercises:

> 
> (...) that Schumann damaged his finger by using a mechanical device that held back one finger while he exercised the others—which was supposed to strengthen the weakest fingers
> 
> 
> 

(From [Wikipedia](https://en.wikipedia.org/wiki/Robert_Schumann))

This story (I really see it as a story, I think it's historically unproven) was told to me to teach me the following things:

* Every piano player knows the situation that your fingers seem too weak or not stretched enough, that's normal on every skill level.
* It's not possible to force rapid performance boosts, especially not by enduring physical pain. Controlled practice with patience is all you can do.
* Respect your hands! Yes, you can practice finger strength or range with the right exercises, but if there is any risk in damaging/hurting them, stop.
Never do something that is causing pain. If your hand cannot do the "stretch" you may have to shift. Is the stretch for a chord or a single note run? 

I would like to add to this that in general it is a good ideal to stretch before playing as a warm up. But never to the point of pain. We all have to deal wit our individual physical limits. Perhaps in time your body will adjust to get the reach it needs but if it's a far reach then probably not. Pain is different than discomfort. Many players experience a feeling of awkwardness as beginners but eventually get comfortable with the instrument and the demands it places on the body. But pain usually means injury and once you injure tendons, joint cartilage etc. they will scar up and that typically reduces mobility. Stretch gently as a warm up and see how it progresses. Never force you hand beyond its range of motion.