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Kinetics of Hula Hooping: An Exploratory Analysis Tyler Cluff D. Gordon E. Robertson Ramesh Balasubramaniam School of Human Kinetics Faculty of Health.

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Presentation on theme: "Kinetics of Hula Hooping: An Exploratory Analysis Tyler Cluff D. Gordon E. Robertson Ramesh Balasubramaniam School of Human Kinetics Faculty of Health."— Presentation transcript:

1 Kinetics of Hula Hooping: An Exploratory Analysis Tyler Cluff D. Gordon E. Robertson Ramesh Balasubramaniam School of Human Kinetics Faculty of Health Sciences University of Ottawa, Ottawa, Canada

2 Hula Hoop

3 Physics of Hula Hooping Conservation of angular momentum Conservation of angular momentum Small, carefully initiated impulses exerted on the interior periphery of hoop Small, carefully initiated impulses exerted on the interior periphery of hoop Vertical component to oppose gravity Vertical component to oppose gravity Dynamic equilibrium achieved by coupled, sustained oscillations about joints of lower extremity Dynamic equilibrium achieved by coupled, sustained oscillations about joints of lower extremity

4 Previous Research Balasubramaniam and Turvey (2004): Balasubramaniam and Turvey (2004): –95% variance accommodated by just two modes –in the large hoop condition, the first mode was a hip dynamical system; fore-aft motion of the hips maintained rotational motion –the second eigenvalue was a knee dynamical system –larger hoop size required more emphasis on the role of the knees to maintain motion of the vertical regulatory component

5 Purpose The purpose of this research was to compare the conclusions reached using dynamical systems theory with those of inverse dynamics/moment power analyses. The purpose of this research was to compare the conclusions reached using dynamical systems theory with those of inverse dynamics/moment power analyses. Are the two theories in agreement with regards to the involvement of the hips and knees in maintaining oscillatory motion of the hoop? Are the two theories in agreement with regards to the involvement of the hips and knees in maintaining oscillatory motion of the hoop?

6 Methods Flow Chart three female participants 5 x 30 s trials at resonant frequency with small hoop (70 cm) Vicon Workstation: 5 MX13 cameras (200 Hz) 2 Kistler force platforms 22 marker trajectories Visual3D v3.79: 7 segment model Inverse dynamics and moment powers

7 Results each figure shows three repetitions averaged across five trials (error bars are ± 1 SD) vertical axes are normalized to body mass top curves are hip, middle are knee, bottom are ankle left side data are from the left limb and vice versa each figure shows three repetitions averaged across five trials (error bars are ± 1 SD) vertical axes are normalized to body mass top curves are hip, middle are knee, bottom are ankle left side data are from the left limb and vice versa

8 Results – hip ab/adductor moments Figure 1. Ab/adductor moments of the ankle, knee and hip joints (Subject 1). hip abductors dominated throughout left and right sides were 180 degrees out-of-phase adductors performed minor role and little work hip abductors dominated throughout left and right sides were 180 degrees out-of-phase adductors performed minor role and little work

9 Results – ab/adductor powers Figure 2. Abductor/adductor powers of the ankle, knee and hip joints (Subject 1). all subjects had similar patterns of the hip abductors and adductors work done at knee was likely not muscular but was likely done by joint structures little or no work done at ankles all subjects had similar patterns of the hip abductors and adductors work done at knee was likely not muscular but was likely done by joint structures little or no work done at ankles

10 Results – ab/adductor powers Figure 2. Abductor/adductor powers of the ankle, knee and hip joints (Subject 1). hip abductors produced negative work immediately afterwards positive work (prestretching?) followed by a brief pause or adductor work while contralateral abductors performed positive work hip abductors produced negative work immediately afterwards positive work (prestretching?) followed by a brief pause or adductor work while contralateral abductors performed positive work

11 S1 Results – knee extensor strategy Figure 3. Flexor/extensor m oments of the ankle, hip and knee (Subject 1). knee extensors dominated throughout left and right sides out-of-phase ankle plantiflexors also contributed knee extensors dominated throughout left and right sides out-of-phase ankle plantiflexors also contributed

12 S1 Results – knee extensor strategy Figure 4. Flexor/extensor powers of the ankle, hip and knee (Subject 1). knee extensors produced positive then negative work while left side did positive work, right did negative work little work by plantiflexors or hip moments knee extensors produced positive then negative work while left side did positive work, right did negative work little work by plantiflexors or hip moments

13 S2 Moments – hip-ankle strategy Figure 5. Flexor/extensor m oments of the ankle, knee and hip joints (Subject 2). hip and knee flexors and extensors are involved ankle plantiflexors dominated throughout hip and knee flexors and extensors are involved ankle plantiflexors dominated throughout

14 S2 Powers – hip-ankle strategy Figure 6. Flexor/extensor powers of the ankle, knee and hip joints (Subject 2). hip flexors and plantiflexors of left side produced the majority of the positive work; right hip extensors assisted little work by knee moments hip flexors and plantiflexors of left side produced the majority of the positive work; right hip extensors assisted little work by knee moments

15 S3 Moments – whole leg strategy Figure 7. Flexor/extensor m oments of the ankle, knee and hip joints (Subject 3). similar to subject 2 but both sides produced equal magnitudes both sides were only slightly out of phase similar to subject 2 but both sides produced equal magnitudes both sides were only slightly out of phase

16 S3 Powers – whole leg strategy Figure 8. Flexor/extensor powers of the ankle, knee and hip joints (Subject 3). left knee flexors & extensors and plantiflexors provided most work with assistance from both hip flexors right knee extensors and plantiflexors provided negative work left knee flexors & extensors and plantiflexors provided most work with assistance from both hip flexors right knee extensors and plantiflexors provided negative work

17 Summary All subjects used the hip abductors to maintain hoop rotational equilibrium All subjects used the hip abductors to maintain hoop rotational equilibrium With same experimental conditions each subject adopted a different strategy to maintain hoop’s vertical equilibrium With same experimental conditions each subject adopted a different strategy to maintain hoop’s vertical equilibrium  Subject 1 relied on the knee extensors  Subject 2 relied on the hip moments and ankle plantiflexors  Subject 3 incorporating the flexors/extensors of the knee and hip and ankle plantiflexors Agreement between dynamical systems theory and inverse dynamics/moment power analyses but in unpredictable ways Agreement between dynamical systems theory and inverse dynamics/moment power analyses but in unpredictable ways Care must be taken when averaging subjects together Care must be taken when averaging subjects together

18 Questions?


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