Weak Links Explored: The Trunk (Part 1)

Over the past several months, we have been diligently testing our beta units against force platforms to make sure we're stacking up. These tests are being done at Blast Athletic in Toronto, PUSH's 'Official Testing Site'. This week, strength coach and owner at Blast, Marv, is going to shed some light on a controversial topic in the field of strength training, the trunk. If I were you, I'd listen to Marv...he's a beast - if you don't believe me, check out the cover image (yep, that's him).

I'll let Marv take it from here.

In recent years, there has been a lot of research and discussion, about the role of the trunk in athletic performance. Everyone from bio-mechanics experts, to therapy practitioners, and strength and conditioning coaches have weighed in on the topic.  For the most part, everyone agrees on the fundamental mechanisms which affect performance, but there is still lots of debate about developing a universal model for achieving the outcomes.  It goes without saying, that strength and conditioning coaches have a significant contribution to make, as we’re the ones who are ultimately tasked with making the decisions which affect the development of millions of athletes worldwide.  If you’re an athlete or fitness enthusiast reading this, we’re going to get you started with some basic concepts.

What is the trunk?

The trunk, or core as it’s commonly known, is comprised of (2) layers.  The deepest layer includes smaller muscles which are designed primarily for stabilization, and are highly utilized in activities which require balance and coordination.

  • Transverse Abdominus
  • Multifidus
  • Quadratus Lumborum
  • Internal Oblique

The superficial layer which is made up of larger muscles, also provide stabilization, but are primarily designed to produce movement.  ie. flexion & extension

  • Rectus Abdominus
  • Erector Spinae
  • External Oblique
  • Gluteus Medius
  • Hip Abductors
  • Quadriceps group
  • Hamstrings

Why is it important to balance the musculature of the trunk?

Balanced trunk development is crucial for (2) very important reasons:

  1. A strong, well balanced trunk will allow you to achieve the most efficient transfer of force possible.  Whether you’re pushing a bobsled, jumping to block a shot, or sprinting down the track – a stable trunk will allow you to perform your task with a lower energy output.  This will enable you to execute a higher volume of quality reps in training, and will translate to better skill performance and stamina during competition.
  2. Trunk stability directly affects the quality of movement that can be achieved in the extremities, and thus has a significant role in injury prevention.   If your goal is to play at a high level, for a long time – then keeping injury at bay, has to be top priority for you.

How can I assess the function of my trunk?

To properly assess the function of your trunk you’ll need to find someone who is trained in performing a functional movement assessment.   It’s very important that you verify both the quality and scope of their expertise.  Depending on the level of weakness or limitation that is uncovered, you may need to be referred to a chiropractor or physiotherapist for further assessment, treatment, or rehab.  Many athletes are shocked at how poorly they score on an initial assessment.   The reason is that athletes are the best compensators!  The same motor ability that allows them to excel at their sport, also allows them to compensate for sometimes glaring structural and neuromuscular deficiencies.

Stay tuned for Part II, where we’ll be discussing corrective exercises, and the framework for progression.


Hodges PW. Core stability exercise in chronic low back pain.  Orthopedic Clinics of North America. 2003;34:245-254

Arnheim DD, Prentice WE. Principles of Athletic Training. 11 ed. St. Louis, MO: Mosby: 2003

Bliss LS, Teeple P. Core stability: the centerpiece of any training program.  Current Sports Medicine Reports. 2002;4:179-183

Eck JC, Riley LH. Return to play after lumbar spine conditions and surgeries.  Clinics in Sport Medicine. 2004;13(1):367-379