The Efficacy of Core Training In Physical Therapy

“My doctor told me I have a weak core”. 

This is a statement we often hear in the outpatient PT setting, and one that usually sends chills down our spines. Although the core can be important in rehabilitation for back pain and other injuries, it may not be the only cause, nor the only solution for your problems. Also, this type of education instills fear in patients that believe that their spine is fragile, or they are “unstable”. The truth is that the human spine is a robust structure designed to move and support you.

“Core strength” is an essential component to athletic performance and participating in many activities of daily living, but we may be approaching it the wrong way! The goal of this publication is to discuss the contemporary view of “the core” and how this may fit (or not fit) into your rehabilitation and your performance training. Below I will highlight principles of core-based training and how these exercises can impact your performance and your health.

Accepted Principles of Core Training

In the PT world, the core is considered a structure that provides stability to the spine, protecting it from damage and aberrant motion, and potentially serving as a source of pain relief. Predominant examples of this school of thought are the McGill big 3 and McKenzie exercises. While these exercises can be helpful and may even reduce a patient’s symptoms, this may not be the most effective strategy for every patient especially, in the lens of functionality. If we take a look at the exercises often prescribed, such as the isometric single leg crunch, side plank, and bird dog; we see isolated, primarily isometric exercises that teach rigidity. Even more concerning, these exercises may promote a feeling or belief that the spine is fragile and needs to be protected.

The Role of Motor Control

When comparing traditional core strengthening and training to interventions in other body regions, a few things are obviously different. One notable difference is that we aim not only to build strength in other body regions through our interventions but also to improve coordination, movement efficiency, and prevent additional injuries. In order to give some context to this perceived disparity I would like to briefly talk about the motor control principle of degrees of freedom. 

Degrees of Freedom

Throughout the body there is anatomic, kinematic, and neurophysiological redundancy. This provides us with exploration of movement and multiple means to achieve an end goal. Through this redundancy, the body has the ability to practice movement patterns on a course towards optimization and this is where the motor control aspect of our story comes into play. This process requires energy to navigate and decide on a path unless an accepted order of operations has already been learned and embedded in our central pattern generators. These theories don’t necessarily line up with the use of a tightly knit one-size-fits-all glove. When we think about the amount of structures we are considering pushing into this box, it becomes increasingly farfetched. 

So what adaptations should we be looking to create with core training and how do we implement this type of intervention? 

If we take a look at the literature, we can find evidence to suggest that core training is beneficial in creating the 3 following outcomes:

1. Enhanced Muscle Stiffness and Endurance

   a. Evidence shows enhanced core strength improves force transfer into the extremities and overall power generation. It seems logical that we should not only perform interventions that influence the extremities throughout various return to sport phases of rehab. If we want to produce a robust sense of preparedness, we should also perform interventions to improve the links of the kinetic chain between said extremities. Along the same lines of thinking, a weak core coupled with strong extremities is thought to result in altered biomechanics and insufficient transfer of force throughout the body (Jha et al 2022). An example of this is presented in a systematic review by De Blaiser et al. 2018, “Significantly lower absolute flexion and extension strength was found in injured compared to uninjured female ski racers”. This allows for a possible correlation between decreased sagittal plane strength and injury rates.

2. Improved Motor Control and Efficiency of Movement

a. The importance of this type of training is stated in the same systematic review by De Blaiser et al. which says, “Core stability is instantaneous and efficient functioning requires the successful integration of adequate muscular characteristics defined by strength and endurance and sensorimotor control, which relies on proprioception and neuromuscular control”. Based on this statement we would be remiss to disregard this type of training if we desire to enhance efficient functioning along the kinetic chain. This idea is further supported in the same article where they found that impaired neuromuscular control was linked to an increase in eccentric activity of lower leg musculature to control altered movement patterns. Another benefit of this style of training is that it has been found to promote neuromuscular reorganization which helps to integrate the instantaneous contraction required to transfer force, which is crucial for athletes who frequently perform dynamic and high-impact movements. 

3. Injury Prevention

a. The final and most important benefit to discuss from core training is injury prevention. Movement in general will decrease the risk of injury occurrence marginally if not more, but can core training make significant decreases in injury risk? 

One secondary analysis found that youth basketball athletes and those participating in physical education classes showed no significant reduction in injury risk following a neuromuscular training program emphasizing core control and proprioceptive abilities. However, in this same study, soccer players demonstrated a significant reduction in injury risk. This doesn’t tell us much aside from the fact that further research needs to be conducted in order to understand what specific population could benefit the most from these types of injury prevention programs. 

Despite this discrepancy, there are a number of studies that illustrate a reduction of injury risk following core based training. One study of interest is a prospective study performed by Khayambashi et al. 2016. In this study, they sought to identify a possible correlation with noncontact ACL injuries in competitive athletes and their baseline proximal strength. They examined the strength of the hip external rotators and abductors using hand-held dynamometry on 501 athletes participating in various sports such as soccer, volleyball, basketball, and handball before the beginning of their season. In general, the average chance of noncontact ACL injury throughout a given sports season is 3%. Throughout the tracked season, 15, or 5%, of their athletes experienced noncontact ACL injuries. These athletes displayed significantly lower values in both hip external rotation and abduction strength. Using a logistic regression model for each strength measurement and the data gathered from this study, specific clinical values were determined to be associated with a higher risk of injury. Athletes classified as high risk on their preseason hip abduction strength test had an increase in the probability of noncontact ACL injury from 3.0% to 7.2%. Athletes classified as low risk on their preseason hip abduction strength test had a decrease in the probability of noncontact ACL injury from 3.0% to 0.65%. Similar results were seen when we used the preseason hip external rotation strength test: Injury risk increased from 3.0% to 6.6% given a high-risk test but decreased from 3.0% to 0.34% given a low-risk test. These clinically significant values are limited by their single appearance in literature, but at face value, they provide ample reason to implement this type of intervention.

Summary

Based on the available research, it is clear that core training has a beneficial role in the rehabilitation and sports performance world. As we seek to optimize functional outcomes in our patients/athletes, we must consider adapting this facet of care. However, core training should not replace foundational movements of associated areas or interventions that have a greater degree of transferability and specificity. Keeping this in mind, it is clear that we can apply typical rehabilitative principles in a more appropriate and particular manner.

If you have questions about how to implement these principles or feel like there is a missing component in your own rehab, reach out to Trifecta Therapeutics to set up a consultation or evaluation. 

Authored by: Dr. Zach Bille, DPT

Edited and Mentored by: Dr. Justin Hanus, PT, DPT, OCS, CSCS

References 

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