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Dynamic Core Strength Influences Upper and Lower Extremity Power

Shinkle J, Nesser TW, Demchak TJ, McMannus DM.  Effects of Core Strength on the Measure of Power in the Extremities. Journal of Strength and Conditioning Research 26(2):373-379, 2012.

PMID: 22228111

RATIONALE AND PURPOSE:  Core stability and strength are frequently described to be important factors for developing maximal power in the extremities.  Previous research has demonstrated that core stability / strength are important factors for endurance and injury prevention.  However, there is limited research to support the importance of core stability / strength on maximal power output in the extremities.  Previous research investigating the influence of core stability / strength on power output of the extremities is limited by only assessing core stability / strength using static assessments.  Thus, limiting our understanding of the importance of core stability / strength on power output.  The purpose of this study was two fold: 1) to develop a functional test of core musculature and 2) to determine the association between a function test of core musculature with the ability to transfer force from the lower to the upper extremities.

OVERVIEW OF RESEARCH METHODS: 25 NCAA Division football athletes participated as subjects in this study.  All subjects underwent a series of tests for core strength and athletic performance.  The core strength tests incorporated a series of different weighted medicine ball throws.  The athletic performance tests incorporated a series of commonly performed tests of power output.

Core Strength Tests (2 trials of each test were performed, the throw with the greatest distance was used for analysis):

  • Dynamic Medicine Ball Throws (Forward, Backward, Right, and Left): During the dynamic medicine ball throws the individual sat on a weight bench with their hips flexed to 90-deg. The trunk was free to move, thus the trunk and upper extremity were used to contribute to the throwing motion.
  • Static Medicine Ball Throws (Forward, Backward, Right, and Left): During the static medicine ball throws the individual sat on a weight bench with their hips flexed to 90-deg and their chest strapped to the back rest.  The trunk was not able to move, thus the upper extremity was the primary contributor to the throwing motion.
  • The medicine ball throw tests were designed to test upper extremity power generation with (dynamic tests) and without (static tests) the use of the core musculature to measure the effect of the core on throw distance.

Athletic Performance Tests:

  • Push Press Power: Performed with 50% of subject’s bodyweight.  A myotest accelerometer was attached to barbell and the participant performed 5 repetitions where average power was recorded.
  • Countermovement vertical jump
  • Proagility shuttle run
  • 40-yard sprint
  • One repetition maximum bench press
  • One repetition maximum squat

Correlational analyses were performed to assess the relationship between measures of core strength and athletic performance for the different variables.

KEY FINDINGS: The dynamic medicine ball throws (tests where core strength is evaluated) were significantly correlated with the following measures of athletic performance:

  • One repetition maximum squat (Dynamic Forward Throw)
  • One repetition bench press (Dynamic Forward Throw)
  • Countermovement vertical jump (Dynamic Throw to Left and Right)
  • Push Press (Dynamic Throw to Left and Right)
  • The Dynamic Throw Backward was not correlated with any measures of the performance variables.

CLINICAL IMPLICATIONS: The dynamic medicine ball throws allow the subjects to obtain a body position that enables them to use their core musculature to improve the distance of the throw.  The Dynamic Medicine Ball Throws (tests of core strength) were measured with some aspect of performance, except for the proagility shuttle run and the 40-yard sprint tests.  Thus, these results demonstrate the core strength is an important factor related to power output of the extremities.  However, core strength seems to be less important for measures of speed (40 yard sprint) and agility (proagility shuttle run).

Previous research has not seen such an association between measures of core strength with physical performance measures.  A likely explanation is that previous research has utilized more static assessment of core strength and endurance, such as a timed prone or side plank test.  While these static measures of core strength and endurance provide important information related to core stability and injury risk, they do not appear to be predictive of physical performance.  Thus, a more comprehensive battery of core strength tests may be needed to fully evaluate core function.  Static tests of core strength/endurance can be used to determine the role of the local stabilizing muscle’s ability to stabilize the spine.  Dynamic tests, such as the medicine ball throws, can be used to assess both the local and global muscles contributions to physical performance.

These findings are important as this is some of the first research to demonstrate the link between core strength and physical performance.  As such, core strength training is supported as a vital aspect for performance enhancement training.

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