Why Understanding Flexibility?

You can probably relate to the following: you want to improve your flexibility and you’re looking for advice or information on how to go about it. You browse around on Instagram, you do a Google search, listen to some podcasts, visit some blog posts and watch some YouTube videos. That’s where the problem starts...

 There’s so much information out there, so many coaches, trainers, influencers, and other sources. And many seem to give contradictory advice. How can you possibly judge the quality of the information? How can you possibly filter through all the options? Are you just doomed to trial and error? Not necessarily.

A good evidence-based knowledge foundation will help you cut through a lot of the poor-quality information out there. It counteracts dependency, as you no longer blindly have to believe or follow what anyone says. You have a solid foundation that can give you guidance in the jungle of information and advice that is out there.

Now, that doesn’t mean you have to become a world expert and study all possible nuances and intricacies. No, you only need a solid understanding of the mechanisms that underly the adaptations that occur with flexibility training and the different methods that we can employ to reach our goals.

Building this foundation of knowledge will stimulate autonomy and competence, allowing you to take responsibility for developing your own physical abilities so you can enjoy the sports and activities that bring joy to your life. 


  • On-demand: watch in your own time and at your own pace

  • Evidence-based: everything is aligned with the scientific literature

  • Build Understanding: not just a “do this” program

  • Understand different adaptations that occur during flexibility training

  • Understand the different methods that you can use to improve your flexibility

  • Understand how and why the different methods work

  • No more confusion

  • Be able to filter through other sources of information and judge them for quality

  • Have a solid toolbox for achieving your flexibility goals


This course will also include a Knowledge Foundation Module. This module contains 5 videos that cover all the fundamentals you need to know to dive deeper into the topic of flexibility. For those who have a background in physiology and anatomy, this will be a great refresher that might deepen your understanding. For those who have no prior background knowledge, it’s a great resource for building that foundation that’s necessary for really understanding topics such as flexibility and strength.

Course details

The Understanding Flexibility course is an on-demand video course. That means you can start at any time and you can study the material at your own pace. You'll have lifetime access to all of the material.

The course includes 2 modules: the Knowledge Foundation and the Understanding Flexibility module.

Module 1: Knowledge Foundation - 5 videos

In the knowledge foundation module, we learn everything we need to know about the structure and function of muscle and connective tissue. We look at some of the characteristics like the force-velocity and length-tension relationship and we look at the neural control of muscle contraction. This module will give you a great foundation for understanding more complex topics like flexibility and strength.

The module contains the following videos:

  • Structure of a Muscle 

  • Function of a Muscle Fiber

  • Characteristics of Muscle Functioning

  • Neural Control of Muscle Contraction

  • Muscle Classification

Module 2: Understanding Flexibility - 6 videos

In the understanding flexibility module, we’re going to do exactly that: understand flexibility in a comprehensive manner. We’re going to look at what happens when we stretch. There are neural components (the sensation of stretch) and mechanical components that happen in the tissue itself. We will also discuss the neural and mechanical adaptations that can occur due to flexibility training. We will discuss the different types of flexibility or mobility and we will discuss all the different methods that we can employ to improve our flexibility. These methods include several different ways of stretching (for example passive, loaded or ballistic) and “hands-on” techniques such as foam rolling or massage. We will give you a complete model that is as simple as possible but not oversimplified.  

The module contains the following videos:

  • Introduction & Definitions

  • Neural Mechanisms: Stretch Tolerance

  • Mechanical Mechanisms

  • Mobility vs. Flexibility

  • Methods for Improving Flexibility: Stretching

  • Methods for improving Flexibility: Foam Rolling

Each video has a discussion section where you can ask your questions and join in on the conversations that are already happening. All your questions will be answered! 

Test your knowledge

After working your way through the two video modules, there will be a quick self-test where you can check if you really understood the material correctly.

Who will be teaching the course?

The Understanding Flexibility Course has been developed by Dr. Erwin Maaswinkel and Virgil Spier. Erwin is a doctor of human movement sciences and an expert at synthesizing academic literature and applying it in practice. Virgil is a former Olympic Athlete in track and field who applies his knowledge and experience at both the recreational as well as the elite performance level. They are both practitioners as well so they don’t just preach, they practice what they preach. 

The course material will be taught predominantly by Erwin.


Sports Fanatic

Louis - Honk Kong

Sports Fanatic

I personally read some materials on sports and I’m surrounded by different experts in coaching, training, rehab, sports science, etc. But no one has ever put all things together and approached it in this way. All the material is organized well and in a way that is easy to understand, while at the same time providing enough details for us to be able to use it in our training, and even with that, it still explains things better than a 3-month college course in human physiology!
Personal Trainer

Stylianos - The Netherlands

Personal Trainer

I feel everything is quite clear from the get-go. Whenever a question or opposing idea arises, there is a healthy conversation that leads to truth-seeking and allows one to think for themselves without forcing a certain concept upon them.
Yoga Teacher

Dian - The Netherlands

Yoga Teacher

The study material is of really high quality. I like the length of the videos. Good to digest, logically ordered, and with the right amount of detail.


You get the Understanding Flexibility Course, including the Knowledge Foundation Module, for the following price.