Core vs Trunk for Trail Runners

Written by ATRA member Stephen R. Santangelo

I prefer to make reference to the body’s mid-section as the “trunk,” rather than the fitness industry’s buzz word of choice — “core.”

The drawback to mid-section training, regardless of what word one chooses as the descriptor, is the focus on the same useless exercises such as crunches, sit ups and their many variations. Research by the renowned Dr. Stuart McGill has shown the aforementioned exercises load the spine with 340 kg. of compressive force per repetition translating to well over 700 pounds of negative force/compression which none of us need. If you’re doing a 100-rep crunch session, simple math tells us you have just placed over 70,000 pounds of combined force on your back! The only ones who will benefit from this type of training are chiropractors, back surgeons and physical therapists; a cost none of need to bear.

Trunk jump

Trunk jump

In order to train the trunk efficiently, one must speed up their intramuscular coordination in order to gain speed and dynamics in their running. Trunk training involves numerous muscles of the midsection, not just the showcase six-pack, but, the deep layer of spinal connective tissue. Though some trunk muscles are designed for flexing and extending, the greater majority are designed to stabilize the body to minimize movement during everyday tasks, including athletic performance. Stabilization development in turn creates greater force production for the athlete and minimizes injury from everyday tasks.

GMS

GMS

Running results in a constant series of rapid firing of muscle fibers which include stretching, contracting and bracing. Combined, this releases elastic energy. Elite sprinters’ trunk muscles fire six times per second and endurance runners at three times per second. Therefore, you can clearly see how traditional ab exercises do not transfer well to athletics.

There are two very important sources of elastic energy – proprioceptors and connective tissue. Proprioceptors sense the stretch and reflexively signal motor neuron to contract the muscle and connective tissue stretch and rebound in elastic fashion.

Box jump

Box jump

The common exercises such as crunches or any ab curl variation as well as planks do not train the elastic energy system to fire the muscles in proper sequence for running. Planks are performed in a horizontal position using the arms as support, isometrically flexing the abs and squeezing the glutes. For runners, nothing can be further from proper bio-mechanics. We do not run in a horizontal position supporting our weight with our arms. We do not isometrically hold our abs, nor do we squeeze our glutes for a 10k trail run. Same for crunches! These exercises create an interference effect which results in negative (improper) firing patterns. Trail runners endure a great deal of ballistics/trunk bracing/shock absorption and ground force; therefore, we must train to develop these qualities.

My four Go-To exercises for runners include box jumps, horizontal jumps, tuck jumps and good mornings with resistance bands.

Horizontal jump

Horizontal jump

Choose only one for each training session and alternate with each workout. It is imperative to only do twice per week and prior to your runs. Each exercise needs to be performed after a dynamic warm up when the body is fresh and the central nervous system (CNS), and joints are ready to accept force. Only perform 6-8 sets of 1 rep at max effort with 1 minute rest between reps. This is about developing neurological pathways and force acceptance, not huffing and puffing. With each jump, the landing must be solid, no little hops or bouncing. This will properly fire the trunk muscles in sequence as it would in running.

The loss of neuro-muscular co-ordination is the primary issue creating anatomical dysfunctions as we move forward in age. The good morning exercise (GM) is the best movement for preventing any malfunction of the body due to hidden weaknesses deep within the trunk. GMs are executed with straight legs and a strong straight back throughout the range of motion.

Pictured are 3 positions; top photo illustrates the novice position, center, intermediate and last is the advance position. Push the hips back as far as possible in the low position. It is very important to pull the band toward the body to keep tension on the posterior chain. This will increase the eccentric power phase (stretch reflex) as well as protecting the back from injury. As you raise your torso thrust the hips forward and drive the chest up. This movement will progressively fire all the muscles of the entire body in a natural sequence which will translate well to running. Also, take a deep breath into the lower chest as you lower the torso. Hold the breath at the bottom. Only exhale at the top of the movement. This will create internal pressure against the inside part of the spine which protects the vertebrae from collapsing. Hold the top position for a 2 count and lower slowly to full extension.

This is the most effective exercise to traction the back for correct running posture by strengthening the deep muscle attachments of the trunk along the spine. Perform 3 sets of 6-8 reps with a 60 second rest between sets.

Use this program as outlined and your running will become more efficient and you will have an enhanced ability to conquer the trails.

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