Athletes often focus on developing a specific set of muscles needed for a particular sport, often overlooking the importance of core stability.


Let us consider two common activities – cycling and running, and how core stability factors into their performance.


Most cyclists focus on the hamstrings, quadriceps and gluteal muscles, and forget about the importance of core stability. Just think about how many hours the cyclist spends bent over in a flexed position on the aero bars, with no rotational or side bending motions.

A strong core is needed to counterbalance these forces. With a focus on the core, a cyclist can generate more power and can sustain a higher level of intensity for longer periods. A stronger core also means less stress on the primary muscle movers and a delay in the build up of lactic acid.

Even minor changes such as brake position can affect core stability.1 For example, if the brake handle position is too low, the cyclist is forced to reach too far forward with their forearms. This reaching position forces the cyclist to raise their head forcing the pelvic girdle posterior. This position can cause a restriction in several key muscles in the core, thus reducing performance.

The ideal position for the forearms is to have the elbows bent and the forearms flattened out. In this position, the cyclist head drops into a more comfortable aerodynamic position, and the pelvis tilts forward. In this position, the cyclist is able to use all the core muscles with improved efficiency.


Now consider how a shortened rectus abdominis affects a tri-athlete’s performance during running. Although opinions about the ‘ideal running form’ vary greatly, most authorities will agree that the less energy that is expended, the more effective and efficient the running style will be.

Common running recommendations are to:

  • Run upright. Your back should be straight, roughly at a 90-degree angle to the ground.
  • Look straight ahead. Your eyes should be focused straight down the road on a point moving about 10 meters in front of you. This helps to keep you in a straight line.
  • Swing your arms naturally. The angle at the elbow between your upper and lower arms should be about 90 degrees. Your hands should be loosely cupped, about belly level.3

How a Shortened Rectus Abdominis Affects Running

A shortened rectus abdominis will pull the runners posture forward causing a braking action that reduces running economy. As the rectus is shortened, it pulls the chest forward allowing gravity to pull the head down.

In order to look straight ahead as instructed, the athlete wastes a considerable amount of force in trying to overcome the contracted rectus abdominis. As the shoulders move forward, a shortened rectus abdominis causes the arms to rotate internally. This makes keeping the arms relaxed at the recommended 90-degree angle much more difficult, thereby reducing running economy.

What to Look For When Analyzing a Runner

When performing a biomechanical analysis, it is very common to see numerous imbalances of which the athlete is completely unaware. By video taping an athlete during activity the practitioner can show and explain what is happening then correct it. When analyzing a runner, some of the most common biomechanical faults looked for are:

• Over-pronation (rolling in as arches collapse) in the feet. This can cause a series of biomechanical imbalances from the foot up to the cervical spine.

• Excessive hip adduction. Due to tight hip adductors and can cause increased load in the lateral tissues such as the iliotibial band, tensor fascia lata and gluteus medius.

• Lack of trunk rotation. Due to restrictions in trunk rotators or shoulder extensors. This can cause overload in the hip musculature, spinal joints and other trunk rotators.

• Lack of hip extension. Caused by tight hip flexors restricting extension, and weak gluteal muscles. This causes the extensors and rotators of the lumbar spine to become overloaded in order to compensate for the lack of hip extension.

• Lack of shoulder extension. Caused by restrictions in anterior shoulder muscles or poor trunk rotation.

Educating yourself on how the core works will help to avoid injury, improve your athletic performance and increase training efficiency.


1. McGill, S, Ultimate Back Fitness and Performance: Ontario. Wabuno Publishers. 2004.

2. Kendall FP, McCreary EK, Provance PG. Muscles: Testing and Function. 4th ed. Philadelphia: Lippincott Williams and Wilkins. 1993.


About the Authors

Charles DeFrancesco is the owner of the education program at Westchester Sports and Wellness ( He is also a consultant for Pure Fitness Group, LLC and Fit and Functional, LLC. He is certified by the National Academy of Sports Medicine (NASM) and by the National Federation of Professional Trainers (NFPT). He is also USAW Olympic lifting certified and Equinox Fitness Group Prenatal certified. Charles has completed specialty courses for Functional Exercise Specialist, Cardiac Conditions (AFPA), attended EFTI, and has over 5,000 hours of clinical experience. He is the NFPT workshop coordinator for the Northeast region, and currently sits on the NFPT Board of Education. He is also a board member of the Ethics and Safety Compliance Standard for personal trainers. Charles is the main author of the Principles of Functional Exercise manual and A Squash Player’s Training Handbook.

Dr. Robert Inesta is a Certified Chiropractic Sports Practitioner and a Certified Strength and Conditioning Specialist. His extensive post graduate training consists of functional rehabilitation, functional soft tissue therapy and biomechanics, clinical neurophysiology and electrodiagnosis and nutrition. He is a certified provider of Active Release Techniques, Graston Technique and Kinesiotaping. Dr. Inesta’s main goal is to help his patients to reach their goals in the most efficient and effective way. He has lectured on topics including sports medicine, functional training, biomechanics, injury prevention and nutrition and has co-authored articles on functional training. He is also a co-author of the training manuals of the National Federation of Professional Trainers.


These resources are for the purpose of personal trainer growth and development through Continuing Education which advances the knowledge of fitness professionals. This article is written for NFPT Certified Personal Trainers to receive Continuing Education Credit (CEC). Please contact NFPT at 800.729.6378 or with questions or for more information.