over extensor strength over a number of years. The basic problem in athletic training is to reduce the ratio of imbalance that is inherent from birth and-intensified by sports participation and the failure of coaches to emphasize the development of a relative balanced muscular strength for coordination and prevention of injury in their training
programs. This normal inherent imbalance is reflected in many muscle groups. The gastrocsoleus is approximately five times as strong as the dorsi-flexors; the triceps are one-third stronger than the biceps, etc. A simple way of functionally testing fore-
extensor-flexor and supination-pronation relative strength is the palms-down, palms-up wrist curl with a barbell and a pronation-supination wrist rotation exercise with a one-end loaded dumbbell handle. These two exercises can also be used for developing balanced strength in the forearm muscles that will prevent the development of tennis elbow. John P. Jesse, ACSM Hermosa Beach, California 90254 arm
Dr. Robert P. Nirschl: &dquo;In response to Mr. Jesse’s letter, the following seems pertinent: 1. The fact that muscle imbalance exists is made perfectly clear on the basis of functional necessity. 2. To alter the normal strength ratio between protagonists and antagonists undoubtedly invites injury to the weaker musculo-tendinous unit. 3. Mr. Jesse’s statement relative to the unimportance of scientific accuracy in muscle testing does not warrant comment.
4. The exercise program he proposes has merit but is incomplete and should also include the abductors and adductors.&dquo;
John P. Jesse: In response to Dr. Nirsch’s observations, the following is offered:
Sirs: 1. There 200
was
no
intention to offer the
exercises mentioned as an exercise program. It was suggested as a practical method of rough testing of muscle strength ratio. 2. Scientific testing of muscle strength ratio is no doubt the best method, as various muscle groups can be tested in various body attitudes. However, this equipment is not readily available, even to doctors specializing in sports medicine. 3.I cannot agree that altering normal strength ratio invites injury. Klein and Allman have demonstrated clearly that thigh flexor-extensor strength imbalance and bi-lateral leg strength imbalance are strong contributing factors to knee injuries. Others have demonstrated the same point in respect to hamstring injuries and thigh adductor strains. The major problem in injury prevention is to reduce the imbalance between opposing muscle groups, that is so commonly found among athletes and laymen. two
Shoe-surface interface Sirs: I believe that Dr. Torg and his colleagues are doing a valuable job in their study of the shoe-interface as it relates to knee injury on various types of turfs (Torg et al: The Shoe-Surface Interface and its Relationship to Football Knee Injuries. J Sports Med
2:261-269, 1974). I noted with interest that cleat length, in group of shoes studied, varied from 3/4 of an inch to 3/8 of an inch. This range, in itself, should make for considerable variation in the coefficients of friction, as demonstrated on testing instruments. I was particularly concerned with the Group III shoe which had the Hanley lock-on heel with 3/4 inch cleats on the front of the sole. I would like to remind Dr. Torg that the National High School Athletic Federation (NHSAF)
one
prohibited the use of the long cleat a number of years ago and that the 3/8 inch cleat is now mandatory on all shoes used in high school competition under NHSAF regulations. A test of the Group IIIshoe (with 3/4 inch cleats and lock-on heel) would naturally be expected to demonstrate this shoe to be more hazardous than other shoes with shorter cleats. I would also like to point out that the New York State High School Athletic Association has made the shoe with lock-on heel and 3/8 inch cleat mandatory for all of its member schools beginning in Januarv, 1976. I’m sure that the New York State Association would not have made this requirement if they had not found this type of shoe to be the safest in terms of potential
injury. May
it suffice to say that the soccer-type shoe advocated by Dr. Torg does not represent the only desirable combination of safety factors, in terms of potential injury. However, I still feel that Dr. Torg’s work is a great contribution to ( 1 ) the understanding of those factors which determine the relative safety of various types of athletic
shoes and (2) the protection of the school athlete.
high
Professor Karl K. Klein Rehabilitation Laboratory The University of Texas at Austin Austin, Texas
Dr. Joseph S. Torg: Professor Klein’s observations regarding Group III shoes with 3/4 inch cleats on the forefoot and the Hanley disc on the heel are well taken. The reason that the longer cleats were used was because of the limits of the assay device which required such an arrangement to obtain equal loading on both the forefoot and the heel. It was not possible to pivot the testing device in the coronal plane, and testing the shoe with the Hanley heel and 1/2 inch cleats resulted in an uneven distribution of load. In his concern over cleat length, Professor Klein has obviously missed the point of our work. That is, it is not the length of the cleats that is as responsible for foot fixation as it is the effect of cleat tip surface area and the nature of the materials of the interacting shoe-surface interface.
201
programs. This normal inherent imbalance is reflected in many muscle groups. The gastrocsoleus is approximately five times as strong as the dorsi-flexors; the triceps are one-third stronger than the biceps, etc. A simple way of functionally testing fore-
extensor-flexor and supination-pronation relative strength is the palms-down, palms-up wrist curl with a barbell and a pronation-supination wrist rotation exercise with a one-end loaded dumbbell handle. These two exercises can also be used for developing balanced strength in the forearm muscles that will prevent the development of tennis elbow. John P. Jesse, ACSM Hermosa Beach, California 90254 arm
Dr. Robert P. Nirschl: &dquo;In response to Mr. Jesse’s letter, the following seems pertinent: 1. The fact that muscle imbalance exists is made perfectly clear on the basis of functional necessity. 2. To alter the normal strength ratio between protagonists and antagonists undoubtedly invites injury to the weaker musculo-tendinous unit. 3. Mr. Jesse’s statement relative to the unimportance of scientific accuracy in muscle testing does not warrant comment.
4. The exercise program he proposes has merit but is incomplete and should also include the abductors and adductors.&dquo;
John P. Jesse: In response to Dr. Nirsch’s observations, the following is offered:
Sirs: 1. There 200
was
no
intention to offer the
exercises mentioned as an exercise program. It was suggested as a practical method of rough testing of muscle strength ratio. 2. Scientific testing of muscle strength ratio is no doubt the best method, as various muscle groups can be tested in various body attitudes. However, this equipment is not readily available, even to doctors specializing in sports medicine. 3.I cannot agree that altering normal strength ratio invites injury. Klein and Allman have demonstrated clearly that thigh flexor-extensor strength imbalance and bi-lateral leg strength imbalance are strong contributing factors to knee injuries. Others have demonstrated the same point in respect to hamstring injuries and thigh adductor strains. The major problem in injury prevention is to reduce the imbalance between opposing muscle groups, that is so commonly found among athletes and laymen. two
Shoe-surface interface Sirs: I believe that Dr. Torg and his colleagues are doing a valuable job in their study of the shoe-interface as it relates to knee injury on various types of turfs (Torg et al: The Shoe-Surface Interface and its Relationship to Football Knee Injuries. J Sports Med
2:261-269, 1974). I noted with interest that cleat length, in group of shoes studied, varied from 3/4 of an inch to 3/8 of an inch. This range, in itself, should make for considerable variation in the coefficients of friction, as demonstrated on testing instruments. I was particularly concerned with the Group III shoe which had the Hanley lock-on heel with 3/4 inch cleats on the front of the sole. I would like to remind Dr. Torg that the National High School Athletic Federation (NHSAF)
one
prohibited the use of the long cleat a number of years ago and that the 3/8 inch cleat is now mandatory on all shoes used in high school competition under NHSAF regulations. A test of the Group IIIshoe (with 3/4 inch cleats and lock-on heel) would naturally be expected to demonstrate this shoe to be more hazardous than other shoes with shorter cleats. I would also like to point out that the New York State High School Athletic Association has made the shoe with lock-on heel and 3/8 inch cleat mandatory for all of its member schools beginning in Januarv, 1976. I’m sure that the New York State Association would not have made this requirement if they had not found this type of shoe to be the safest in terms of potential
injury. May
it suffice to say that the soccer-type shoe advocated by Dr. Torg does not represent the only desirable combination of safety factors, in terms of potential injury. However, I still feel that Dr. Torg’s work is a great contribution to ( 1 ) the understanding of those factors which determine the relative safety of various types of athletic
shoes and (2) the protection of the school athlete.
high
Professor Karl K. Klein Rehabilitation Laboratory The University of Texas at Austin Austin, Texas
Dr. Joseph S. Torg: Professor Klein’s observations regarding Group III shoes with 3/4 inch cleats on the forefoot and the Hanley disc on the heel are well taken. The reason that the longer cleats were used was because of the limits of the assay device which required such an arrangement to obtain equal loading on both the forefoot and the heel. It was not possible to pivot the testing device in the coronal plane, and testing the shoe with the Hanley heel and 1/2 inch cleats resulted in an uneven distribution of load. In his concern over cleat length, Professor Klein has obviously missed the point of our work. That is, it is not the length of the cleats that is as responsible for foot fixation as it is the effect of cleat tip surface area and the nature of the materials of the interacting shoe-surface interface.
201
