BOOK CHAPTER PUBLICATIONS

Escamilla, R.F.  Aerobic and anaerobic exercise in the older patient.  In K.P. Speer, The Graying of Sports Medicine – Treating the Active Patient Over 50.  Human Kinetics, In Press.

Introduction: This chapter presents evidence regarding how aerobic and anaerobic exercise can attenuate, and in some cases reverse, most physiologic changes that are associated with aging. It focuses on three areas related to aerobic and anaerobic exercise in the aging population over 50 years of age:

1.                  Current research findings on the effects of aerobic and anaerobic exercise

2.   Aerobic and anaerobic exercise testing

3.  Aerobic and anaerobic exercise prescription

Escamilla, R.F. & Wickham, R.  Exercise based conditioning and rehabilitation.  In G. Kolt & L. Snyder-Mackler, Physical Therapies in Sports and Exercise. Churchill Livingstone: 2003.

Introduction: This chapter presents evidence for the use of exercise in injury prevention and rehabilitation. Specific areas covered will include strength and plyometrics training, interval training, endurance training, and stabilization training.  Strength training has been shown to be effective in injury prevention and rehabilitation by increasing muscle, ligament, and tendon strength and size. As well, strength training can increase bone strength and density, decrease the risk of osteoporosis, decrease risk of falling and subsequent injury, improve gait stability, walking speed, and efficiency, increase stair climbing and chair raising ability, and increase balance.  Plyometric training is helpful in enhancing muscle strength and power, which decreases an athlete’s injury risk by allowing muscles and connective tissue to absorb more energy.  Interval training allows a greater volume of work to be performed compared to continuous training.  Endurance training is important in enhancing the cardiovascular system, which improves overall function and enhances the rehabilitation process.  Stabilization training is important in enhancing the core strength of the body.

REFERRED JOURNAL PUBLICATIONS

Elliott, B., Fleisig, G.S., Nicholls, R., & Escamilla, R.F.  Technique effects on upper limb loading in the tennis serve.  Journal of Science and Medicine in Sport, Vol 6 (1): 76-87, 2003.

Abstract: The purpose of this study was to compare the shoulder and elbow joint loads during the tennis serve. Two synchronized 200 Hz video cameras were used to record the service action of 20 male and female players at the Sydney 2000 Olympics. The displacement histories of 20 selected landmarks, were calculated using the direct linear transformation approach. Ball speed was recorded from the stadium radar gun.  The Peak Motus system was used to smooth displacements, while a customized inverse-dynamics program was used to calculate 3D shoulder and elbow joint kinematics and kinetics. Male players, who recorded significantly higher service speeds (male =183 km hr^-1: female = 149 km hr^-1) recorded significantly higher normalized and absolute internal rotation shoulder torque at the position when the arm was maximally externally rotated (MER) (male = 4.6% and 64.9 Nm: female = 3.5% and 37.5 Nm). A higher absolute elbow varus torque (67.6 Nm) was also recorded at MER, when compared with the female players (41.3 Nm).Peak normalized horizontal adduction torque (male = 7.6%: female = 6.5%), normalized shoulder compressive force (male = 79.6%: female = 59.1%) and absolute compressive force (male = 608.3 N: female = 363.7 N), werehigher for the male players. Players who flexed at the front knee by 7.6°, in the backswing phase of the serve, recorded a similar speed (162 km hr^-1), and an increased normalized internal rotation torque at MER (5.0 %), when compared with those who flexed by 14.7°. They also recorded a larger normalized varus torque at MER (5.3% v 3.9%) and peak value (6.3% v 5.2%). Players who recorded a larger knee flexion also recorded less normalized and absolute (4.3%, 55.6 Nm) peak internal rotation torque compared with those with less flexion (5.6%, 63.9 Nm). Those players, who used an abbreviated backswing, were able to serve with a similar speed and recorded similar kinetic values.  Loading on the shoulder and elbow joints is higher for the male than female players, which is a reason for the significantly higher service speed by the males.  The higher kinetic measures for the group with the lower knee flexion means that all players should be encouraged to flex their knees during the backswing phase of the service action. The type of backswing was shown to have minimal influence on service velocity or loading of the shoulder and elbow joints.

Fleisig, G.S., Nicholls, R.L., Elliott, B.C., Escamilla, R.F.  Kinematics used by world class tennis players to produce high-velocity serves.  Sports Biomechanics, 2(1): 51-64, 2003.

Abstract

The purpose of this study was to quantify ranges and speeds of movement, from shoulder external rotation to ball impact, in the tennis service actions of world class players.  Two electronically synchronized 200 Hz video cameras were used to record 20 tennis players during singles competition at the Sydney 2000 Olympic games.  Three-dimensional motion of 20 landmarks on each player and racquet were manually digitized.  Based upon the mean values for this group, the elbow flexed to 104º and the upper arm rotated back into 172º of shoulder external rotation as the front knee extended.  From this cocked position, there was a rapid sequence of segment rotations.  The order of maximum angular velocities was trunk tilt (280º/s), upper torso rotation (870º/s), pelvis rotation (440º/s), elbow extension (1510º/s), wrist flexion (1950º/s), and shoulder internal rotation.  Shoulder internal rotation was greater for males (2420º/s) than females (1370º/s), which may be related to the faster ball velocity produced by the men (50.8 vs. 41.5 m/s).  Although both genders produced segment rotations in the same order, maximum upper torso velocity occurred earlier for females (0.075 seconds before impact) than for males (0.058 s).  At impact, the trunk was tilted 48º above horizontal, the arm was abducted 101º and the elbow, wrist, and lead knee were slightly flexed.  Male and female players should be trained to develop the kinematics measured in this study in order to produce effective high-velocity serves.

Escamilla, R.F., Fleisig, G.S., Barrentine, S.W., Andrews, J.R., & Moorman, C.T., III.  Kinematic and kinetic comparisons between American and Korean professional baseball pitchers.  Sports Biomechanics, 1(2): 213-228, 2002.

Abstract: The purpose of this study was to quantify and compare kinematic, temporal, and kinetic characteristics of American and Korean professional pitchers in order to investigate differences in pitching mechanics, performance, and injury risks among two different cultures and populations of baseball pitchers.  Eleven American and eight Korean healthy professional baseball pitchers threw multiple fastball pitches off an indoor throwing mound positioned at regulation distance from home plate.  A Motion Analysis three-dimensional automatic digitizing system was used to collect 200 Hz video data from four electronically synchronized cameras.  Twenty kinematic, six temporal, and 11 kinetic variables were analyzed at lead foot contact, during the arm cocking and arm acceleration phases, at ball release, and during the arm deceleration phase.  A radar gun was used to quantify ball velocity.  At lead foot contact, the American pitchers had significantly greater horizontal abduction of the throwing shoulder, while Korean pitchers exhibited significantly greater abduction and external rotation of the throwing shoulder.  During arm cocking, the American pitchers displayed significantly greater maximum shoulder external rotation and maximum pelvis angular velocity.  At the instant of ball release, the American pitchers had significantly greater forward trunk tilt and ball velocity and significantly less knee flexion, which help explain why the American pitchers had 10% greater ball velocity compared to the Korean pitchers.  The American pitchers had significantly greater maximum shoulder internal rotation torque and maximum elbow varus torque during arm cocking, significantly greater elbow flexion torque during arm acceleration, and significantly greater shoulder and elbow proximal forces during arm deceleration.  While greater shoulder and elbow forces and torques generated in the American pitchers helped generate greater ball velocity for the American group, these greater kinetics may predispose this group to a higher risk of shoulder and elbow injuries.

PUBLISHED CONFERENCE ABSTRACTS/PROCEEDINGS

Escamilla, R.F.  Biomechanics and pathomechanics of the throwing shoulder and elbow: insight into the injury mechanism.  Medicine and Science in Sports and Exercise, 36(5): 2004. 

Abstract: An understanding of proper throwing mechanics can enhance performance and minimize injuries.  The purpose of this tutorial was to provide insight into the injury mechanism to the shoulder and elbow by integrating throwing biomechanics (joint and segment angles, angular velocities, forces and torques, and muscle activity) with common pathomechanics that result from throwing.  High speed videography and cadaveric specimens will be employed to enhance visual representation and provide a more clear explanation to how shoulder and elbow injuries can occur during throwing, and how training and rehabilitation can be used to minimize injury potential and enhance the rehabilitation process.

Escamilla, R.F., McCaw, S.T., Salem, G.J.  Biomechanics of lower extremity functional exercise: rehabilitation and neuromuscular considerations.  Medicine and Science in Sports and Exercise, 36(5): 2004.

Abstract: The squat, leg press, leg extension, and step-up are common open and closed chain lower extremity exercises used in rehabilitation settings, such as after ACL reconstruction, and also used by athletes training for sport. Understanding how lower extremity joint forces, torques, and muscle activity vary among the above functional exercises is helpful to the therapist, trainer, and coach in selecting and prescribing appropriate exercises during rehabilitation and training.  The object of this mini-symposium was to present lower extremity electromyographic, joint force and torque data while performing the squat, leg press, leg extension, and step-up in order to better understand how different exercises affect muscle recruitment patterns, ACL/PCL tensile loads, patellofemoral compressive loads, and ankle, knee, and hip torques as a function of joint angle, load lifted, and technique variation.

Escamilla, R.F., Tonini, C.D., Lai, I.Y., Lowry, T.M., Hreljac, A., and Imamura, R.T.  Biomechanical analysis of sumo and conventional deadlifts in females during the special Olympics world games.   Medicine and Science in Sports and Exercise, 35(5), S322: 2003. 

Abstract: Improper lifting techniques may increase injury risks and decrease performance. The aim of this study was to compare and contrast biomechanical parameters between sumo and conventional style deadlifts and between high and low skilled lifters who participated in the Powerlifting event during the 1999 Special Olympics World Games. Two synchronized video cameras collected 60 Hz data from 40 subjects. Parameters were quantified at barbell liftoff (LO), when the barbell passed the knees (KP), and at lift completion.  Compared to the conventional group, the sumo group had a 100% greater stance width, 20% smaller hand width, 10% less vertical bar distance, a more vertical trunk at LO, a more horizontal thigh at LO & KP, a less vertical shank at KP, and greater forefoot abduction. The sumo group generated ankle dorsiflexor, knee extensor, and hip extensor moments, while the conventional group produced ankle plantar flexor, knee flexor & extensor, and hip extensor moments. Compared to low skilled lifters, high skilled lifters had a 40% greater barbell load, 15% greater stance width (sumo group only), greater knee flexion at LO (conventional group only), greater knee extension at KP, a less vertical shank position at LO (sumo group only), 15% less vertical bar distance, less first peak bar velocity between LO and KP (conventional group only), smaller plantar flexor and hip extensor moment arms at LO and KP, and greater knee extensor moment arms at LO.  The sumo deadlift may be more effective in working ankle dorsiflexors and knee extensors, while the conventional deadlift may be more effective in working ankle plantar flexors and knee flexors.  High skilled lifters exhibited better lifting mechanics than low skilled lifters by keeping the bar closer to the body, which may both enhance performance and minimize injury risk.

SCIENTIFIC AND PROFESSIONAL PRESENTATIONS:

Biomechanics and pathomechanics of the throwing shoulder and elbow: insight into the injury mechanism.  Presented at the 51^st Annual Meeting of the American College of Sports Medicine, Indianapolis, IN, May 2004.

Biomechanics of lower extremity functional exercise: rehabilitation and neuromuscular considerations.  Presented at the 51^st Annual Meeting of the American College of Sports Medicine, Indianapolis, IN, May 2004.

Biomechanics of the Throwing Shoulder.  Presented at the 2003 California Physical Therapy Association Annual Conference, Sacramento, CA, October 2003.

 An electromyographic analysis of commercial and common abdominal exercises.  Presented at the 2003 California Physical Therapy Association Annual Conference, Sacramento, CA, October 2003.

 Biomechanical analysis of sumo and conventional deadlifts in females during the special oylmpics world games.  Presented at the 50^th Annual Meeting of the American College of Sports Medicine, San Francisco, CA, May 2003.

 Exercises for the trunk and lower extremity.  Presented at the 21th Annual Injuries in Baseball Course, American Sports Medicine Institute, Atlanta, GA, January 2003.