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Isolation and compound core exercises

This is an excerpt from NSCA's Guide to Program Design 2nd Edition by NSCA -National Strength & Conditioning Association.

By Ronald L. Snarr and Lawrence W. Judge

While many exercise variations exist, core-specific movements can be separated into two distinct categories: isolation and compound (6). Isolation exercises place the focus onto a specific muscle group or joint and include isometric (e.g., planks) and dynamic (e.g., crunches) movements. In contrast, compound exercises incorporate two or more primary joints and engage multiple muscle groups while increasing the use of synergistic musculature (e.g., back squat) (33). For athletes looking to improve sport performance, it is important to include a mixture of compound and isolation movements in a strength and conditioning program. Programming both types of exercises can improve core stability, which can help to maintain posture of the trunk and supporting structures (e.g., pelvic girdle) as well as assist in body control during both static and dynamic movement (20).

When choosing compound exercises, it is important to consider the involvement of the core musculature. For example, the bench press and push-up are both considered compound movements; however, the involvement of the trunk is limited in the bench press because the exercise is completed in a lying, stable position. Due to this stable position during the bench press, motor unit excitation of the rectus abdominis has been shown to decrease by approximately 50% compared to a traditional push-up (9), thus minimizing the adaptations to the core.

Compound and isolation exercises can also be broken down further into movements that use either a single side (i.e., unilateral) or both sides (i.e., bilateral) of the body. For example, a traditional back squat is a bilateral compound movement performed using both legs, whereas a single-leg squat would be classified as a unilateral compound movement. Bilateral exercises are often more stable because the individual has more points of contact with a surface (e.g., multiple limbs). Thus, the unilateral alternative to a given exercise requires greater balance and stability to successfully complete the movement (4, 8, 28). For example, the unilateral seated shoulder press increases erector spinae, external oblique, and rectus abdominis motor unit excitation by 45%, 81%, and 49%, respectively, compared to the bilateral version (28). Despite these increases in core musculature activity, it is important to note that bilateral movements may enhance muscular strength to a greater extent compared to unilateral movements. Therefore, if the goal of the athlete is to improve muscular strength, bilateral compound exercises should be prioritized.

Unilateral exercises can also be divided into ipsilateral (i.e., same side) and contralateral (i.e., opposite side), which, for core-specific movements, may involve the upper body, lower body, or a combination of the upper and lower body. For instance, lateral side bends, a dynamic exercise targeting the external obliques, are considered a contralateral exercise. When the weight is held in the right hand (i.e., unilaterally), the athlete laterally flexes the spinal column to the right. To complete the side bend, the athlete returns to a standing position by using the left external oblique and left spinal erectors in a concentric action. Since the musculature on the opposing side is acting to produce the movement, lateral side bends are considered an isolation contralateral exercise. Regarding ipsilateral exercises, lying heel taps would be classified as an ipsilateral isolation exercise because the right external obliques are used to flex the spinal column laterally to touch the right heel.

The last classification to consider when programming core-specific movements is the difference between dynamic and isometric exercise. Dynamic exercises incorporate the shortening and lengthening of skeletal muscle to produce movement in multiple planes of motion (e.g., wood choppers), while isometric exercises consist of an increase in muscular tension without a subsequent movement (e.g., planks). Dynamic movements of the trunk allow for the transfer of force and power between the upper and lower body, and isometric training involves using the ability to brace and stabilize the trunk when resisting external forces, whether expected or unexpected. Isometric core training has also been shown to increase stability, postural balance, and muscular endurance while decreasing the likelihood of injury and low back pain (13). Thus, it is recommended to include a combination of dynamic and isometric movements in an athlete’s strength and conditioning regimen to train the core through various planes of motion while also increasing the individual’s ability to brace and stabilize the trunk when appropriate.

More Excerpts From NSCA's Guide to Program Design 2nd Edition

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