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Biomechanics of running shoes
N”
BOOK
REVIEW
BIOMECHANICS OF RUNNING SHOES Benno M. Nigg (Ed.), Human Kinetics Publishers, Champaign, IL, 1986, 180 pp., $24.95 This unique monograph will be useful to a limited number of persons, although it is disappointing. The various chapters form a compilation of research efforts conducted over the last decade by a group of investigators affiliated with two institutions well-known for their sports biomechanics. This group has been premier among those conducting research specifically on running shoes. As the editor notes, there are two principal reasons for conducting such research: to improve performance and to reduce the fnzquency of injuries. The major disappointment, then, is that little of the book substantively addresses these two critical issues. Furthermore, the reader is not presented a comprehensive strategy by which one might determine whether a particular sort of shoe accomplished either goal. This major deficiency prevents the book from being the valuable, as well as unique, reference it might have been. The problem is perhaps reflected in the imprecision with which the goal of the book was formulated: ‘Thirteen years have passed since the beginning of this project, and so it seems appropriate to present our group’s most appropriate findings. .’ . The book has been addressed to ‘those connected with research in running shoes’. ‘those involved in the production or distribution of running shoes’, ‘those who use running shoes and want to know what shoe to buy and why’: a broad audience to reach in one small volume. The second major disappointment is that the book heavily emphasizes the ‘mechanics’ at the expense of the ‘biology’. In this sense, calling it a monograph of’biomechanics’ is almost a misnomer. Most of the work addresses the sometimes excellently presented mechanics of the running shoes/surfaces without addressing the critical biological responses of the runner, particularly those which occur over time and would likely affect either performance or injury. Knowing how the shoe interfaces with the running surface, for example, is certainly important, but it is also important to know how the shoe interfaces with the runner. Nonetheless, certain portions of the book will be of value to certain individuals. The first chapter ‘Biomechanical Aspects of Running’ summarizes and provides references on the incidence of running injuries. For the person not familiar with many of the concepts of mechanics, the importance of loading rates is discussed. The second chapter, ‘Experimental Techniques Used in Running Shoe Research’, provides a nice summary of a number of techniques used by this group of researchers to study running shoes. This will prove to be quite readable for those individuals, including lay persons, not familiar with such experimental techniques. However, this chapter does not review the numerous other techniques needed to address the two critical issues about running shoes. For example. there is no mention of methods to study foot-shoe contact pressures; there is no mention of appropriate methods needed to determine whether or not a particular shoe actually reduces injury rates. A conceptual approach (best described as reductionist) to the study of injuries is presented at the end of the chapter which might be useful for identifying certain characteristics of shoes producing certain sorts of injury pattrms. How this approach could be used to identify a ‘best’ shoe (whether for a given runner or a group of runners) is not clear.
The third chapter, ‘Load on the Locomotor system and Modelling’, is the centerpiece of the monograph, and the longest chapter. The major thrust of this chapter is to describe the methods used to estimate forces and moments acting on and in the lower extremity and the material properties of shoes, running surfaces, and the skeletal elements. These methods are central to future studies which might contribute to better understanding of the mechanical relationship between the shoe and the runner. In the words of the writer: ‘At this time, such models are not in use in running shoe research’. No clear approaches are outlined in which such models could be used, and while such approaches might be obvious to the experienced researcher, neither the ag proaches nor their limitations would be obvious to those unfamiliar with such techniques. Furthermore, this material may prove to be dificult for the layperson, although most students of biomechanics will find it to be fairly straightforward. For the most part, the modelling approaches have been well and accurately described. However, there are a few places in which the wording is either awkward or in which it could lead to misconceptions. For example, in the section entitled ‘The solution has to fulfil additional constraints’, there appears to be confusion between a ‘constraint’ and a cost function. This confusion is of more than semantic importance since in the optimization literature, each of these terms has quite specific and different meanings. In fact, a solution need not fulfil additional ‘constraints’ as is stated, although it must fulfil ‘conditions’ which, as presented, are clearly cost functions, rather than constraints. The fourth chapter, ‘Special Aspects of Shoe Construction and Foot Anatomy’, provides the reader with an intriguing but brief history of shoe construction and the basic terminology to describe the relevant parts of the shoe. Those not familiar with various foot conditions will find the de&ptions of foot postures and deformities helpful. The fifth chapter outlines studies of three major factors thought to influence running injuries: impact forces, pronation, and supination. These studies are descriptive in nature, demonstrating the ranges of measures of these three factors. Studies relating these factors to performance or injury are not included. The final chapter concludes with comments on the factors useful in purchasing running shoes. Runners should find this chapter to be useful, although many of the recommendations are empirical, arising from a person experienced in running and the coaching of running, rather than the sort based on ‘hard’ science. In summary, this unique volume will find limited use. Whtle the topic is timely, the book fails to meet its implicit promise. It will be of greatest use to young researchers looking for a usable central source in the study of running shoes. It will be of less use to established sports researchers owing to its parochial nature, and of less use to others in biomechanics because of its lack of comprehensiveness and failure to address the major questions about running shoes. Richard A. Brand Unioersiry
of Iowa
BOOK
REVIEW
BIOMECHANICS OF RUNNING SHOES Benno M. Nigg (Ed.), Human Kinetics Publishers, Champaign, IL, 1986, 180 pp., $24.95 This unique monograph will be useful to a limited number of persons, although it is disappointing. The various chapters form a compilation of research efforts conducted over the last decade by a group of investigators affiliated with two institutions well-known for their sports biomechanics. This group has been premier among those conducting research specifically on running shoes. As the editor notes, there are two principal reasons for conducting such research: to improve performance and to reduce the fnzquency of injuries. The major disappointment, then, is that little of the book substantively addresses these two critical issues. Furthermore, the reader is not presented a comprehensive strategy by which one might determine whether a particular sort of shoe accomplished either goal. This major deficiency prevents the book from being the valuable, as well as unique, reference it might have been. The problem is perhaps reflected in the imprecision with which the goal of the book was formulated: ‘Thirteen years have passed since the beginning of this project, and so it seems appropriate to present our group’s most appropriate findings. .’ . The book has been addressed to ‘those connected with research in running shoes’. ‘those involved in the production or distribution of running shoes’, ‘those who use running shoes and want to know what shoe to buy and why’: a broad audience to reach in one small volume. The second major disappointment is that the book heavily emphasizes the ‘mechanics’ at the expense of the ‘biology’. In this sense, calling it a monograph of’biomechanics’ is almost a misnomer. Most of the work addresses the sometimes excellently presented mechanics of the running shoes/surfaces without addressing the critical biological responses of the runner, particularly those which occur over time and would likely affect either performance or injury. Knowing how the shoe interfaces with the running surface, for example, is certainly important, but it is also important to know how the shoe interfaces with the runner. Nonetheless, certain portions of the book will be of value to certain individuals. The first chapter ‘Biomechanical Aspects of Running’ summarizes and provides references on the incidence of running injuries. For the person not familiar with many of the concepts of mechanics, the importance of loading rates is discussed. The second chapter, ‘Experimental Techniques Used in Running Shoe Research’, provides a nice summary of a number of techniques used by this group of researchers to study running shoes. This will prove to be quite readable for those individuals, including lay persons, not familiar with such experimental techniques. However, this chapter does not review the numerous other techniques needed to address the two critical issues about running shoes. For example. there is no mention of methods to study foot-shoe contact pressures; there is no mention of appropriate methods needed to determine whether or not a particular shoe actually reduces injury rates. A conceptual approach (best described as reductionist) to the study of injuries is presented at the end of the chapter which might be useful for identifying certain characteristics of shoes producing certain sorts of injury pattrms. How this approach could be used to identify a ‘best’ shoe (whether for a given runner or a group of runners) is not clear.
The third chapter, ‘Load on the Locomotor system and Modelling’, is the centerpiece of the monograph, and the longest chapter. The major thrust of this chapter is to describe the methods used to estimate forces and moments acting on and in the lower extremity and the material properties of shoes, running surfaces, and the skeletal elements. These methods are central to future studies which might contribute to better understanding of the mechanical relationship between the shoe and the runner. In the words of the writer: ‘At this time, such models are not in use in running shoe research’. No clear approaches are outlined in which such models could be used, and while such approaches might be obvious to the experienced researcher, neither the ag proaches nor their limitations would be obvious to those unfamiliar with such techniques. Furthermore, this material may prove to be dificult for the layperson, although most students of biomechanics will find it to be fairly straightforward. For the most part, the modelling approaches have been well and accurately described. However, there are a few places in which the wording is either awkward or in which it could lead to misconceptions. For example, in the section entitled ‘The solution has to fulfil additional constraints’, there appears to be confusion between a ‘constraint’ and a cost function. This confusion is of more than semantic importance since in the optimization literature, each of these terms has quite specific and different meanings. In fact, a solution need not fulfil additional ‘constraints’ as is stated, although it must fulfil ‘conditions’ which, as presented, are clearly cost functions, rather than constraints. The fourth chapter, ‘Special Aspects of Shoe Construction and Foot Anatomy’, provides the reader with an intriguing but brief history of shoe construction and the basic terminology to describe the relevant parts of the shoe. Those not familiar with various foot conditions will find the de&ptions of foot postures and deformities helpful. The fifth chapter outlines studies of three major factors thought to influence running injuries: impact forces, pronation, and supination. These studies are descriptive in nature, demonstrating the ranges of measures of these three factors. Studies relating these factors to performance or injury are not included. The final chapter concludes with comments on the factors useful in purchasing running shoes. Runners should find this chapter to be useful, although many of the recommendations are empirical, arising from a person experienced in running and the coaching of running, rather than the sort based on ‘hard’ science. In summary, this unique volume will find limited use. Whtle the topic is timely, the book fails to meet its implicit promise. It will be of greatest use to young researchers looking for a usable central source in the study of running shoes. It will be of less use to established sports researchers owing to its parochial nature, and of less use to others in biomechanics because of its lack of comprehensiveness and failure to address the major questions about running shoes. Richard A. Brand Unioersiry
of Iowa