Sit-ups are a hugely popular exercise with many people using them as part of their training program.
For all the good points that come with sit-ups though, like all exercises, there are some things to keep in mind when doing them regularly.
One of these things to consider is the impact sit-ups can have on your knees.
You might think that sit-ups have nothing to do with your knees as they target your upper body with a strong focus on your abs and core.
However, your legs are involved in sit-ups which means your knees play a part too.
In this article, we discuss whether sit-ups are good or bad for your knees.
In it, we look at whether sit-ups could hurt your knees (and why), as well as exploring how to do sit-ups if you have bad knees and whether sit-ups could actually strengthen your knees too.
Are Sit-Ups Good or Bad For Your Knees?
As a general rule, sit-ups aren’t particularly good or bad for your knees.
Sit-ups are generally considered a safe exercise when they’re performed properly with the correct technique, body position, and after a thorough warm-up to prepare the working muscles.
This means that the risk of injury during sit-ups is relatively low.
Just because the risk of injury is low, it doesn’t mean that sit-ups are good for your knees either.
Injuries can certainly happen if things go wrong, but even if they don’t, your knees aren’t really working in a way that can benefit them too much.
If you’re looking for an exercise that’s safe for your knees, then sit-ups fit the bill. However, if you want an exercise to benefit your knees, there’ll be better ones out there to choose from.
Can Sit-Ups Hurt Your Knees?
Usually, sit-ups will unlikely cause any damage to your knees.
That being said, you could experience some pain and discomfort in your knees as some of the smaller muscles that surround them activate during sit-ups.
As these muscles are placed under stress during the movement, they could feel tight, sore, uncomfortable, and even a little painful afterward. This can then lead to your knees hurting after you do sit-ups.
Despite that, sit-ups shouldn’t actually hurt your knees. As your knees are joints rather than muscles, they aren’t engaging or activating during sit-ups.
This means that they should stay in a pretty stable and stationary position keeping them safe and secure during the exercise.
While accidents can happen and things can go wrong, sit-ups are usually a fairly safe exercise for your knees.
Why Do Your Knees Hurt During Sit-Ups?
If you find that your knees are hurting during sit-ups, it could be a sign that something is wrong with your technique.
As sit-ups shouldn’t have much of an impact on your knees (either positive or negative), any pain or discomfort in that area of your body could be an indication that something is going wrong with your technique and you should double-check everything is correct before continuing.
Even seemingly small errors in your technique can have a much larger impact on the effectiveness and focus of sit-ups.
Any pain felt in your knee (whether exercising or not) could be due to an injury in the joint itself.
When you’re doing sit-ups, your knees aren’t really placed under too much stress so they shouldn’t be painful during the movement.
If you can feel pain in your knees during sit-ups, it could be a good idea to see a medical professional who should be able to rule out or confirm a knee injury.
If you do have an injury in your knees, you may need to follow the advice and guidance of your medical team to ensure you recover as quickly as possible.
Why Do Your Knees Crack During Sit-Ups?
One of the main causes of cracking in your knees during exercise (and sit-ups) is a build-up of gas in the synovial fluid (the fluid inside your knee joints), that’s forced out due to the stress and pressure placed on your knees during certain movements.
During sit-ups, your knees aren’t placed under too much pressure though, so while cracking could be due to gas escaping the joint, it could also be a sign of poor knee cap alignment or other potential medical issues or injuries.
If your knees crack excessively or painfully during sit-ups, seeking medical advice will probably be your best course of action to find out the cause.
Do Sit-Ups Strengthen Your Knees?
Not particularly as the exercise primarily focuses on your abs and core.
While some of the muscles surrounding your knees activate during sit-ups, they aren’t usually placed under enough stress to help strengthen your knees.
If you’re looking to strengthen your knees, there are far better-suited exercises out there that you can choose from other than sit-ups.
How To Do Sit-Ups With Bad Knees
If you have bad knees, sit-ups may still be suitable as part of your training program.
However, it could be that it’s not possible to do sit-ups in their regular form with some specific knee conditions.
The best thing to do is to always follow the advice and guidance of your medical team as they’ll be best placed to tell you the most effective way of helping your knees to recover (or at least not get worse).
You may need to switch to either bent leg sit-ups or to straight leg sit-ups depending on how your knees feel.
You may also need to start with a low number of reps and sets and build up these numbers gradually to ensure you don’t work your knees too hard.
I’ve been in the fitness and strength training industry for nearly a decade. In that time, I’ve gained 30 pounds of muscle, written hundreds of articles, and reviewed dozens of fitness supplements. As for my educational background, I’m a currently studying for my Active IQ Level 3 Diploma in Personal Training.