The Fitness Zone

Using Kettlebells to Increase Hamstring Flexibility

Apr 21, 2022 | by Tarek Chouja

Kettlebells have been around for hundreds of years, and have become standard apparatus in gyms worldwide over the past couple of decades. Only recently, however, have researchers delved into the distinct benefits of this training tool.

In this article, our Industry Partners at Functional Training Institute (FTI) look at how the traditional hip hinge swing can increase hamstring flexibility.

What’s the go with ‘tight’ hamstrings?

We’ve all heard, or given, the diagnosis of ‘tight hammies’, either in relation to our clients, ourselves or others. But why are hamstrings commonly perceived as being ‘tight’?

The nature of modern-day living has changed how we move our bodies, and this has included a steady decrease in our use of the posterior chain. As adults, bending over from the lumbar spine is easier than bending over at the hip, so over time the hamstring becomes dormant, dehydrated, and weak. Because of this, when people are asked to express hamstring flexibility, it is often laughed at as being ‘short’ and ‘tight.’ Performing static stretches, which has been the norm for many years, will not help this situation much because the tension is usually due to a fascial restriction, and fascia cannot be stretched.

So, how does the kettlebell swing increase hamstring flexibility? 

The kettlebell swing is classified as ‘agile strength’. Agile strength improves our ability to produce force to generate and maintain momentum. To sustain momentum, the body looks to capture potential energy from our elastic tissues (fascia, skin, ligaments and tendons) which reduces the amount of total energy expenditure required to perform a momentum-based task.

As such, the kettlebell swing uses more of the connective tissue system than it does the muscular system. Think of a kettlebell swing vs a barbell RDL; once the muscles have created momentum, the muscular system is then only contracted statically twice during a swing. The glutes will contract at the end range of the hip hinge, and at lockout of hip extension to stop the momentum and change direction. It’s the role of the connective tissue that acts as an elastic band to keep the bell swinging every rep.

There are a couple of things that happen inside the hamstring while swinging that will increase its flexibility. Firstly, a muscle contraction can be seen as squeezing a sponge that helps circulate blood and water within the muscle belly; this also happens to the fascial coating around the muscle once it is stretched under load to an incompressible state, flushing it with new blood and rehydrating the tissue. This helps reduce friction in the tissues as you try to lengthen your hamstring muscles.

The second way a swing can increase flexibility is through increasing strength; when a muscle is weak and not stable enough to perform a task, particularly an eccentric contraction, the nervous system will not allow the range to occur due to safety concerns.

The kettlebell swing will stretch, hydrate, and build strength in those ranges previously unreachable. The nervous system will learn to feel safety in eccentric contraction at end range, and will maintain the muscle’s flexibility long-term.

Go forth and get flexible friends!


AIF is partnered with Functional Training Institute to bring world class functional education to students and graduates. AIF Warriors receive access to $500 off Functional Training Institute’s Master Functional Trainer (MFT) and Movement Restoration Coach (MRC) courses.

Tarek Chouja

Tarek Chouja

The Functional Training Institute (FTI) are an official Industry Partner of AIF.
Find out more about Tarek and FTI at or by following @Coach_Tarek@FTIGlobal on social media.

Read more articles

View all articles

Disclaimer: Where Certificate III in Fitness, Cert III/Cert 3, or Fitness Coach is mentioned, it refers to SIS30321 Certificate III in Fitness. Where Certificate IV in Fitness, Cert IV/Cert 4, or Personal Trainer is mentioned, it refers to SIS40221 Certificate IV in Fitness. Where Master Trainer Program™ is mentioned, it refers to Fitness Essentials and SIS40221 Certificate IV in Fitness. Where Master Trainer Plus+ Program™ is mentioned, it refers to SIS30321 Certificate III in Fitness and SIS40221 Certificate IV in Fitness. Where Certificate IV in Massage or Cert IV/Cert 4 is mentioned, it refers to HLT42021 Certificate IV in Massage Therapy. Where Diploma of Remedial Massage is mentioned, it refers to HLT52021 Diploma of Remedial Massage.