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Unformatted text preview: UNSTABLE RESISTANCE EXERCISES Jeffrey M. Willardson, PhD, CSCS This paper was presented as part of the NSCA Hot Topic Series. All information contained herein is copyright of the NSCA. www.nsca-lift.org Hot Topics: Unstable Resistance Exercises www.nsca-lift.org 2 Resistance exercise has been recognized as an essential component of a comprehensive training program for all athletes (1, 3). The types of resistance exercises performed are dictated by the specific physiological and biomechanical demands of a sport or position within a sport (1, 3, 18, 25). In recent years, there has been increased emphasis on performing resistance exercises in unstable body positions. Because sports skills are often performed in unstable body positions, (i.e. running forehand in tennis, baseball pitcher wind-up, shooting a puck while balancing on a single skate blade in hockey), these types of resistance exercises have been widely promoted as being sports specific (7, 9, 12, 19, 22, 24). Resistance exercises performed in unstable body positions have been hypothesized to increase the muscular strength and muscular endurance of the core musculature, which may translate to more powerful and efficient movement patterns and less risk of injury (7, 9, 12, 19, 22, 24). The term core is used to collectively describe a group of muscles that stabilize the lumbar spine and pelvis. Some of these muscles include: the rectus abdominis, transversus abdominis, internal and external oblique, erector spinae, and multifidi (5, 10, 14, 21). Hodges and Richardson (14) demonstrated that when subjects performed a unilateral shoulder movement, the transversus abdominis was the first of the trunk muscles to become active, and this activation occurred prior to the onset of actual limb movement. This study suggests that for the throwing athlete, core stability would be important as force is transferred from the ground, up through the lower extremities, across the trunk, and out to the throwing arm. Several factors determine the extent to which stability is challenged when performing a resistance exercise. The stability demands of resistance exercises can be increased through modifications in the base of support (stable surface versus unstable surface), body position (seated versus standing), the type of equipment used (machines versus free weights), or how the exercise is performed (unilateral versus bilateral) (2, 4, 5, 10, 15, 20, 21). Research has demonstrated increased muscle activation in the core musculature consequent to performing resistance exercises on unstable surfaces. For example, Cosio-Lima, Reynolds, Winter, Paolone, and Jones (10) demonstrated that untrained women significantly improved core muscle activity and static balance to a greater extent by performing Swiss ball exercises versus conventional floor exercises. Vera-Garcia, Grenier, and McGill (21) demonstrated that untrained men approximately doubled abdominal muscle activity when a curl-up was performed on a Swiss ball versus a stable bench. Behm, Leonard, Young, Bonsey, and Mackinnon (5) demonstrated that recreationally trained men and women exhibited...
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This note was uploaded on 07/26/2009 for the course 3534 3535 taught by Professor Nelson during the Spring '09 term at LSU.
- Spring '09