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The Core Ratios: The Personal Trainers Guide To Assessing & Programming For The Core

Written by Rachel Frances Thomson

Introduction

A key component of training stability and control for movement and sports is understanding the strength ratios around the trunk or core. This essential aspect of core assessment and training is often overlooked in the fitness industry. Without balanced strength ratios, clients are at a higher risk of injury.

Why Are Core Strength Ratios Important?

Consider this: would you train your core by doing side bridges on only one side? It wouldn’t make sense, yet many core training programs lack balance, often focusing on flexion (e.g., plank variations) without enough extension exercises. This imbalance neglects the principle that muscles work in pairs, leading to either flexion-dominant or extension-dominant programs. To create effective core training routines, personal trainers need to measure and consider their clients’ core strength ratios.

Fortunately, Professor Stuart McGill from Waterloo University has conducted extensive research on this topic. His studies, initially involving 20 athletes and later expanding to 150 subjects of various demographics, found consistent core strength ratios.

How to Test Core Strength Ratios

To assess a client’s core strength ratios, follow these steps for isometric core ratio testing:

  • Isometric Flexion
  • Isometric Side Bridging (both sides)
  • Isometric Extension

Each test should be performed in this order, timed, and observed for technique. Clients must hold each position as long as possible without encouragement to ensure natural results.

Calculating the Ratios

After testing, calculate the core strength ratios:

  • Draw a Grid: Note the times in seconds for each test.
  • Calculate Ratios: Divide the flexion time by the extension time to get the flexor-to-extensor strength ratio. Repeat for side bridging to assess lateral flexor strength ratios, which can indicate asymmetries.

Using the Data to Build Training Programs

With the ratios calculated, you can design a balanced training program:

  • Flexor Training: If the flexor ratio is low, incorporate isometric flexion exercises.
  • Lateral Training: If one side’s ratio is low, include isometric side bridging.
  • Extension Training: If the extension ratio is low, add isometric extension exercises.
  • Monitor progress closely and re-measure ratios regularly to prevent overcompensation.

Achieving Balance and Stability

Once the ratios align with the norms, shift the focus to endurance for stability and trunk control.

Enhance Your Training Skills

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