Motion Analysis Research Laboratory

The Motion Analysis Research Laboratory (MARL) is located on the campus of IUPUI. It is affiliated with both the IU Department of Physical Therapy and the Department of Orthopaedic Surgery in the IU School of Medicine. The director of the MARL is Dr. Tracy A. Dierks, Assistant Professor within the Department of Physical Therapy. The MARL is housed on the second floor of Coleman Hall, room 222. Click here for MARL contact information and directions.

What is the Motion Analysis Research Laboratory?

The MARL is a multi-faceted biomechanics research center that is dedicated to investigating, understanding, and treating both normal and abnormal human movement. The primary research objectives are focused on the biomechanics and motor control of running and walking. Specific areas of inquiry include:

1. Mechanisms contributing to lower extremity running injuries

   This research is aimed at understanding the relationship between lower extremity function and running related overuse injuries.

   Methodology and variables of interest include joint coupling/coordination, joint kinematics, joint kinetics, impact forces and shock attenuation, muscle activation patterns, structural alignment, and injury history, to name a few.

   Injuries of interest include common running overuse injuries, such as patellofemoral pain syndrome, iliotibial band syndrome, stress fractures, and plantar fasciitis.

2. The role of variability in human movement patterns

   • This research is essentially two-fold:
   • To understand how movement variability of both kinematics and kinetics is associated with normal, uninjured lower extremity function during gait.
   • To determine how this variability may be associated with gait related injuries, such as running overuse injuries.

   Methodology includes the Dynamical Systems Theory and related components, such as continuous relative phasing and vector coding, and Chaos Theory and related components, such as Lyapunov exponent and correlation dimension.

   

3. The effect of fatigue on lower extremity function during gait

   This research is aimed at understanding how running or walking in a fatigued state influences lower extremity function and injury risk.

   Methodology and variables of interest are similar to those in numbers 1 and 2.

4. Intervention techniques to reduce the risk of running related injuries

   

   The long term goal of the gait research within the MARL is to identify the variables that increase the risk of gait related injuries. Once identified, it is hoped that intervention techniques can be applied to reduce the risk of injury.

   These interventions include:

   • Retraining a person's gait mechanics through the use of realtime feedback
   • The use of foot orthoses
   • Muscle strengthening of the lower extremity and core

Equipment in the Motion Analysis Research Laboratory

In order to meet the research objectives, the MARL is equipped with the following high-tech equipment:

• 6 Camera Vicon MX3 240 Hz 3D motion capture system
• 2 Camera 60 Hz Vicon Reference Video system
• Vicon Real Time feedback system
• Bertec Instrumented Treadmill
• 2 AMTI Force Plates
• 2 PCB piezoelectric accelerometers
• 10 Channel Motion Lab Systems EMG unit
• 8 Channel Delsys EMG System
• Marquette 2000 Treadmill
• Biodex System 3
• GAITRite walkway system
• PEDAR-System pedography analyzer
• Customized Arch Height Measurement System

How is the Research Conducted?

The MARL equipment is used to collect motion analysis data. Generally, the first step is to attach light-reflective markers to a subject's lower extremities. As the subject runs or walks down the runway, or on one of the treadmills, each of the 6 high-speed motion capture cameras records the position of each marker throughout the entire movement. The marker coordinates from each camera are then combined to create 3D coordinates for each marker. The position of a marker relative to other markers is used to calculate joint angles, such as knee flexion and foot eversion. Using joint angles, it is possible to derive other kinematic variables. Since the high-speed cameras do not record actual video, the 2 camera reference system is used to capture video footage of the movement and is synchronized with the 3D data and force data for qualitative interpretation.

Forces that act on the body during the movement are also collected. When the subject runs or walks down the runway, ground reaction force data are collected when the subject steps-on or "hits" the 2 force plates. When the subject runs or walks on the instrumented treadmill, 2 force plates mounted within the treadmill bed record ground reaction force data with each footfall. The ground reaction force data are used to determine the forces that are subjected to the body when the subject pushes into the ground from a front-to-back, side-to-side, and a vertical direction. Impact acceleration data are collected by way of the piezoelectric accelerometers. An accelerometer is attached at various points on the body, such as the ankle, and the acceleration that occurs when the foot strikes the ground gives an indication of how ground impact force or "shock" is absorbed by the body.

By combining the information obtained from the cameras and from the force plates, the inverse dynamics method is used to calculate joint moments and subsequent variables. The information derived from this method gives an estimate of the muscular effort or work required to perform the movement. On the other hand, muscle activity data are collected using the EMG system. Surface mounted electrodes and/or fine-wire needle electrodes are used to measure the electrical activity of the muscles. From a motor control perspective, this data indicates when a muscle is being used or when it is "on" and when it is not being used or "off."

Recent Publications

Dierks, TA, & McClay Davis, I. Discrete and continuous joint coupling relationships in uninjured recreational runners. Clinical Biomechanics (In Review).

Stergiou, N, Deffeyes, JE, Dierks, TA, and Kurz, MJ. Number of footfalls necessary to calculate the Lyapunov exponent from accelerometer gait data. Journal of Biomechanics (In Review).

Dierks, TA, Davis, I, and Hamill, J. (2006). Lower extremity joint timing during prolonged treadmill running in runners with patellofemoral joint pain. ACSM 53rd Annual Meeting, Denver, CO, 2006.

Mullineaux, DR, Dierks, TA, and Davis, I. (2006). Variability in coordination of leg kinematics in males and females during treadmill running. ACL Research Retreat III, Lexington, KY, 2006.

Dierks, TA, Davis, I, Manal, KT, and Hamill, J. (2005). Kinematics of runners with and without patellofemoral pain during prolonged treadmill running. Proceedings of the International Society of Biomechanics XXth Congress/29th annual convention of ASB, Cleveland, Ohio, August 2005.

Dierks, TA, Davis, I, Scholz, J, Manal, KT, and Hamill, J. (2005). Hip strength and hip kinematics during prolonged running in runners with patellofemoral joint pain. Medicine and Science in Sports and Exercise, 37(5), s157.

DeLeo, AT, Dierks, TA, Ferber, R, & McClay Davis, I. (2004). Lower extremity joint coupling during running: a current update. Clinical Biomechanics, 19, 983-991.

Dierks, TA, Davis, I, & Hamill, J. (2004). Lower extremity joint coupling in runners who developed patellofemoral pain syndrome. Proceedings of the 28th annual convention of ASB, Portland, Oregon, September 2004.

Dierks, TA, & Davis, I. (2004). Lower extremity joint coupling and patellofemoral joint pain during running. Medicine and Science in Sports and Exercise, 36(5), s56.

Lab Contact Information and Directions

Laboratory Director

Dr. Tracy Dierks - PhDAssociate Professortdierks@iupui.edu317-274-3147 Biography

Mailing Address:

Motion Analysis Research Lab
c/o Dr. Tracy Dierks
1140 W Michigan St
Coleman Hall 326
Indianapolis, IN, 46202

Driving Directions:

From I-65 S or I-65 N: (Note: from I-70 W, merge onto I-65 N via Exit 83B)

• Exit onto Dr. Martin Luther King Jr. St (exit 114)
• Turn Right onto W 11th St (one-way)
• Turn Left onto N University Blvd
• Turn Right onto W Michigan St. (one-way)
• Coleman Hall is on the Right side of the Street
• Turn Right onto West Dr
• Parking: The Riley Hospital parking garage (hourly rates) is located directly behind Coleman Hall

From I-70 E, take the West St. Exit (exit 79A)

• Turn Left onto Missouri St.
• Missouri St. becomes West St.
• Turn Left onto W Michigan St (one-way)
• Coleman Hall is on the Right side of the Street
• Turn Right onto West Dr.
• Parking: The Riley Hospital parking garage (hourly rates) is located directly behind Coleman Hall