kinematic sequencing differences between dancers … dancers (20m, 20f) and forty collegiate...

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Forty dancers (20M, 20F) and forty collegiate athletes (20M, 20F) performed single-leg countermovement jumps to 50% of their maximum jump height (takeoff analysis) and drop-landings from a 30 cm platform (landing analysis). -Female Dancers: Ht: 170.5±7.1 cm; Wt: 56.8±6.0 kg, Age:26 ±5 yrs -Female Athletes: Ht: 176.6±8.1 cm; Wt: 67.6±7.5 kg, Age: 20 ±1 yrs - Male Dancers: Ht: 184.6±7.0 cm; Wt: 73.5±9.4 kg, Age: 27 ±6 yrs - Male Athletes: Ht: 185.6±7.0 cm; Wt: 78.8±13.6 kg, Age: 22 ±2 yrs Biomechanical Analysis: •22 reflective markers were placed on the lower extremity and motion data collected using eight infrared cameras (Motion Analysis Corp.; 250 Hz). For takeoff: ankle plantarflexion, knee extension and hip extension velocities were calculated and defined as positive values (Visual 3D). •The propulsive phase of each jump was defined from the end of the countermovement (i.e. lowest point of the COM) to the moment of takeoff. (Figure 1) For landing: ankle dorsiflexion, knee flexion and hip flexion velocities were calculated and defined as positive values (Visual 3D) •The landing phase was defined from initial contact with the floor to maximal knee flexion during the trial. •The velocity profile of each joint was normalized to the respective maximum velocity achieved by that joint during each takeoff or landing. Trials were also time-normalized to the total time of the propulsive or landing phase. Statistics: •Chi-square analysis was used to compare the incidence of correct kinematic sequencing among the four groups. •Multivariate ANOVA (Sex x Activity) were used to compare the time intervals between peak velocities of adjacent joints. •Distinct proximal-to-distal and distal-to-proximal kinematic sequences were evident for takeoff and landing in 85% of the dancers (34 of 40), but only in 50% of athletes (20 of 40) (P = 0.0016). Dancers were more likely than athletes to demonstrate correct kinematic sequence, likely because of their intense training in jumping aesthetics. During takeoff, female dancers appear to utilize their hips more effectively than female athletes to generate initial propulsion. Female dancers also appear to utilize their ankles more effectively to absorb the initial impact of landing. The more rapid transfer of joint velocities, from the hip to the knee in takeoff, and from the ankle to the knee in landing, for female athletes versus dancers indicates a knee-dominant strategy. Kinematic Sequencing Differences Between Dancers and Team-Sport Athletes During Jumping and Landing Karl Orishimo 1 , Ian Kremenic 1 , Evangelos Pappas 2 , Marshall Hagins 3 , Marijeanne Liederbach 4 1 Nicholas Institute of Sports Medicine and Athletic Trauma, North Shore LIJ Lenox Hill Hospital, New York, NY 2 University of Sydney, Discipline of Physiotherapy, Lidcombe, New South Wales, Australia 3 Long Island University, Division of Physical Therapy, Brooklyn, NY 4 Harkness Center for Dance Injuries, NYU Langone Medical Center Hospital for Joint Diseases, New York, NY Introduction Materials and Methods Results The propulsive phase of a stretch-shortening cycle movement, such as a countermovement jump, is characterized by a proximal-to-distal transfer of joint velocities. Peak hip extension velocity precedes peak knee extension velocity, which in turn precedes peak plantarflexion velocity. This sequence of joint and segmental rotations contributes to the optimal acceleration of the center of mass to reach the desired jump height. [1,2] Similarly, during landing, energy is absorbed through the kinetic chain in a distal-to-proximal pattern with the ankle reaching peak dorsiflexion velocity first, followed by peak knee flexion velocity, followed by peak hip flexion velocity. From a very early age (about 6-8 years of age), dancers receive rigorous training specifically targeting jumping, landing and balance ability. Throughout the course of their daily training and practice, dancers perform numerous (>200) jumping and landing activities. [3] Due to their extensive training in jumping activities, dancers are considered experts in these tasks. Previous research has shown an association between the timing of maximal joint velocities and skill level in team handball players. [4] Therefore, kinematic sequence analysis of jumping may distinguish expert jumpers from less-skilled jumpers. Purpose: To compare lower extremity kinematic sequence during single-leg countermovement jumps and drop- landings between male and female dancers and team-sport athletes. Discussion and Conclusions References 1. Bobbert MF and van Ingen Schenau. J Biomech. 21. 249-262 2. Bobbert MF and van Soest AJ. Exerc. Sport Sci. Rev. 29. 95-102. 2001 3. Liederbach M, et al. J Athl Train. 41. S85 2006 4. Wagner H., et al. J Sports Science. 30. 21-29. 2012 Abstract The propulsive phase of a countermovement jump is characterized by a proximal-to-distal transfer of joint velocities, with peak hip extension velocity preceding peak knee extension velocity, which in turn precedes peak plantarflexion velocity. During landing, this follows a distal-to-proximal pattern. Due to their extensive training in jumping and landing activities, dancers are considered experts in these tasks and would be expected to demonstrate optimal kinematic sequences. Purpose: To compare lower extremity kinematic sequence during single-leg countermovement jumps and drop-landings between male and female dancers and team-sport athletes. Methods: Forty dancers (20M, 20F) and forty collegiate athletes (20M, 20F) performed single-leg countermovement jumps to 50% of their maximum jump height (takeoff analysis) and drop-landings from a 30 cm platform (landing analysis). Kinematics were measured with eight infrared cameras and 22 reflective markers. For each subject, the velocity profile of each joint was normalized to the maximum velocity achieved by that joint during each activity. Repeated-measures ANOVA were used to compare the timing of peak joint velocities. Results: Distinct proximal-to-distal and distal-to-proximal kinematic sequences were evident for takeoff and landing in 85% of the dancers (34 of 40), but only in 50% of athletes (20 of 40) (P = 0.0016). During takeoff, the time from peak hip velocity to peak knee velocity was longer in female dancers compared to female athletes (17±10 msec vs. 11±7 msec, P = 0.04). During landing, the time from peak ankle velocity to peak knee velocity was longer in female dancers compared to female athletes (28±6 msec vs. 21±6 msec, P = 0.002). There were no differences for males. Conclusions: Dancers were more likely than athletes to demonstrate correct kinematic sequence, likely because of their intense training in jumping aesthetics. During takeoff, female dancers appear to utilize their hips more effectively than female athletes to generate initial propulsion. Female dancers also appear to utilize their ankles more effectively to absorb the initial impact of landing. The more rapid transfer of joint velocities, from the hip to the knee in takeoff, and from the ankle to the knee in landing, for female athletes versus dancers indicates a knee-dominant strategy. Landing •The time from peak ankle velocity to peak knee velocity was longer in dancers compared to athletes (26±6 msec vs. 22±6 msec, P < 0.001). •This interval was significantly longer in female dancers compared to female athletes (28±6 msec vs. 21±6 msec, P = 0.002), but no difference was found between male dancers and male athletes (P = 0.061). 0 1 2 3 4 5 6 7 8 9 Female Dancers Female Athletes Male Dancers Male Athletes Takeoff Landing Takeoff •A significantly longer interval between peak hip velocity and peak knee velocity was found in the dancers compared to the athletes (16 ± 6 msec vs. 12 ± 6 msec, Main Effect of Activity, P = 0.024) •This interval was significantly longer in female dancers compared to female athletes (17±10 msec vs. 11±7 msec, P = 0.04), but no difference was found between male dancers and male athletes (P = 0.297). Takeoff Landing Figure 1: Correct (A and C) and incorrect (B and D) examples of kinematic sequences for takeoff and landing Figure 2: Occurrences of incorrect kinematic sequences during takeoff and landing between groups Figure 3: During takeoff, time intervals between peak hip and knee maximum velocity, as denoted by the red area, is longer in female dancers compared to female athletes Figure 4: During landing time intervals between peak ankle and knee maximum velocity, as denoted by the red area, is longer in female dancers compared to female athletes Takeoff Landing Scan here to download

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Page 1: Kinematic Sequencing Differences Between Dancers … dancers (20M, 20F) and forty collegiate athletes (20M, 20F) performed single-leg countermovement jumps to 50% of their maximum

Forty dancers (20M, 20F) and forty collegiate athletes (20M, 20F) performed single-leg countermovement jumps to 50% of their maximum jump height (takeoff analysis) and drop-landings from a 30 cm platform (landing analysis).

-Female Dancers: Ht: 170.5±7.1 cm; Wt: 56.8±6.0 kg, Age:26 ±5 yrs -Female Athletes: Ht: 176.6±8.1 cm; Wt: 67.6±7.5 kg, Age: 20 ±1 yrs - Male Dancers: Ht: 184.6±7.0 cm; Wt: 73.5±9.4 kg, Age: 27 ±6 yrs - Male Athletes: Ht: 185.6±7.0 cm; Wt: 78.8±13.6 kg, Age: 22 ±2 yrs

Biomechanical Analysis:

• 22 reflective markers were placed on the lower extremity and motion data collected using eight infrared cameras (Motion Analysis Corp.; 250 Hz). • For takeoff: ankle plantarflexion, knee extension and hip extension velocities were calculated and defined as positive values (Visual 3D). • The propulsive phase of each jump was defined from the end of the countermovement (i.e. lowest point of the COM) to the moment of takeoff. (Figure 1) • For landing: ankle dorsiflexion, knee flexion and hip flexion velocities were calculated and defined as positive values (Visual 3D) • The landing phase was defined from initial contact with the floor to maximal knee flexion during the trial.

• The velocity profile of each joint was normalized to the respective maximum velocity achieved by that joint during each takeoff or landing. Trials were also time-normalized to the total time of the propulsive or landing phase.

Statistics: • Chi-square analysis was used to compare the incidence of correct kinematic sequencing among the four groups. • Multivariate ANOVA (Sex x Activity) were used to compare the time intervals between peak velocities of adjacent joints.

• Distinct proximal-to-distal and distal-to-proximal kinematic sequences were evident for takeoff and landing in 85% of the dancers (34 of 40), but only in 50% of athletes (20 of 40) (P = 0.0016).

Dancers were more likely than athletes to demonstrate correct kinematic sequence, likely because of their intense training in jumping aesthetics. During takeoff, female dancers appear to utilize their hips more effectively than female athletes to generate initial propulsion. Female dancers also appear to utilize their ankles more effectively to absorb the initial impact of landing. The more rapid transfer of joint velocities, from the hip to the knee in takeoff, and from the ankle to the knee in landing, for female athletes versus dancers indicates a knee-dominant strategy.

Kinematic Sequencing Differences Between Dancers and Team-Sport Athletes During Jumping and Landing

Karl Orishimo1, Ian Kremenic1, Evangelos Pappas2, Marshall Hagins3, Marijeanne Liederbach4 1Nicholas Institute of Sports Medicine and Athletic Trauma, North Shore LIJ Lenox Hill Hospital, New York, NY

2University of Sydney, Discipline of Physiotherapy, Lidcombe, New South Wales, Australia 3Long Island University, Division of Physical Therapy, Brooklyn, NY

4Harkness Center for Dance Injuries, NYU Langone Medical Center Hospital for Joint Diseases, New York, NY

Introduction

Materials and Methods

Results

The propulsive phase of a stretch-shortening cycle movement, such as a countermovement jump, is characterized by a proximal-to-distal transfer of joint velocities. Peak hip extension velocity precedes peak knee extension velocity, which in turn precedes peak plantarflexion velocity. This sequence of joint and segmental rotations contributes to the optimal acceleration of the center of mass to reach the desired jump height. [1,2] Similarly, during landing, energy is absorbed through the kinetic chain in a distal-to-proximal pattern with the ankle reaching peak dorsiflexion velocity first, followed by peak knee flexion velocity, followed by peak hip flexion velocity.

From a very early age (about 6-8 years of age), dancers receive rigorous training specifically targeting jumping, landing and balance ability. Throughout the course of their daily training and practice, dancers perform numerous (>200) jumping and landing activities. [3] Due to their extensive training in jumping activities, dancers are considered experts in these tasks. Previous research has shown an association between the timing of maximal joint velocities and skill level in team handball players. [4] Therefore, kinematic sequence analysis of jumping may distinguish expert jumpers from less-skilled jumpers. Purpose: To compare lower extremity kinematic sequence during single-leg countermovement jumps and drop-landings between male and female dancers and team-sport athletes.

Discussion and Conclusions References 1.  Bobbert MF and van Ingen Schenau. J Biomech. 21. 249-262 2.  Bobbert MF and van Soest AJ. Exerc. Sport Sci. Rev. 29. 95-102. 2001 3.  Liederbach M, et al. J Athl Train. 41. S85 2006 4.  Wagner H., et al. J Sports Science. 30. 21-29. 2012

Abstract The propulsive phase of a countermovement jump is characterized by a proximal-to-distal transfer of joint velocities, with peak hip extension velocity preceding peak knee extension velocity, which in turn precedes peak plantarflexion velocity. During landing, this follows a distal-to-proximal pattern. Due to their extensive training in jumping and landing activities, dancers are considered experts in these tasks and would be expected to demonstrate optimal kinematic sequences. Purpose: To compare lower extremity kinematic sequence during single-leg countermovement jumps and drop-landings between male and female dancers and team-sport athletes. Methods: Forty dancers (20M, 20F) and forty collegiate athletes (20M, 20F) performed single-leg countermovement jumps to 50% of their maximum jump height (takeoff analysis) and drop-landings from a 30 cm platform (landing analysis). Kinematics were measured with eight infrared cameras and 22 reflective markers. For each subject, the velocity profile of each joint was normalized to the maximum velocity achieved by that joint during each activity. Repeated-measures ANOVA were used to compare the timing of peak joint velocities. Results: Distinct proximal-to-distal and distal-to-proximal kinematic sequences were evident for takeoff and landing in 85% of the dancers (34 of 40), but only in 50% of athletes (20 of 40) (P = 0.0016). During takeoff, the time from peak hip velocity to peak knee velocity was longer in female dancers compared to female athletes (17±10 msec vs. 11±7 msec, P = 0.04). During landing, the time from peak ankle velocity to peak knee velocity was longer in female dancers compared to female athletes (28±6 msec vs. 21±6 msec, P = 0.002). There were no differences for males. Conclusions: Dancers were more likely than athletes to demonstrate correct kinematic sequence, likely because of their intense training in jumping aesthetics. During takeoff, female dancers appear to utilize their hips more effectively than female athletes to generate initial propulsion. Female dancers also appear to utilize their ankles more effectively to absorb the initial impact of landing. The more rapid transfer of joint velocities, from the hip to the knee in takeoff, and from the ankle to the knee in landing, for female athletes versus dancers indicates a knee-dominant strategy.

Landing • The time from peak ankle velocity to peak knee velocity was longer in dancers compared to athletes (26±6 msec vs. 22±6 msec, P < 0.001). • This interval was significantly longer in female dancers compared to female athletes (28±6 msec vs. 21±6 msec, P = 0.002), but no difference was found between male dancers and male athletes (P = 0.061).

0 1 2 3 4 5 6 7 8 9

Female Dancers

Female Athletes

Male Dancers

Male Athletes

Takeoff Landing

Takeoff • A significantly longer interval between peak hip velocity and peak knee velocity was found in the dancers compared to the athletes (16 ± 6 msec vs. 12 ± 6 msec, Main Effect of Activity, P = 0.024)

• This interval was significantly longer in female dancers compared to female athletes (17±10 msec vs. 11±7 msec, P = 0.04), but no difference was found between male dancers and male athletes (P = 0.297).

Takeoff Landing

Figure 1: Correct (A and C) and incorrect (B and D) examples of kinematic sequences for takeoff and landing

Figure 2: Occurrences of incorrect kinematic sequences during takeoff and landing between groups

Figure 3: During takeoff, time intervals between peak hip and knee maximum velocity, as denoted by the red area, is longer in female dancers compared to female athletes

Figure 4: During landing time intervals between peak ankle and knee maximum velocity, as denoted by the red area, is longer in female dancers compared to female athletes

Takeoff

Landing

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