This chapter reports a short, but comprehensive,discussion of one of the most vital problems inbiomechanics, that is the ill-posed problem of timedifferentiation of noisy position data. Chapter 5 dealswith dynamometry with special reference to the techni-ques used to manufacture the force plates used inpostural and locomotion studies and equipment, bothwearable and non-wearable, for pressure distributionmeasurement; but no comment is made on theimportant topics of calibration procedures and require-ments. Relevant data as obtained during walking,running, and jumping are reported and discussed. Alsothe stabilometric use of force plates is given someemphasis. Chapter 6 presents issues related to themeasurement of the electrical activity of the skeletalmuscle. It starts with an interesting historical overviewand then it provides a general discussion of the mostcommonly used techniques used in kinesiological

electromyography. The general outline of the chapteris good and the different parts appear well balanced.Terminology is appropriate and the complex matter ispresented in a rigorous fashion. Chapter 7 adds a fewpractical remarks about clinical gait analysis and a briefreference to marker-less photogrammetric systems. Thebook ends with two appendices that include publisheddocuments relative to kinematic and electromyographicdata reporting.

This is a book which would be useful on the shelves oflibraries of institutions which teach or undertakeprojects in biomechanics of human movement in generaland locomotion in particular.

Aurelio CappozzoIstituto Universitario di Scienze Motorie,

Piazza Lauro de Bosis, 15, 00194 Roma, Italy

E-mail address: cappozzo@iusm.it

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The biomechanics of back pain

M.A. Adams, N. Bogduk, K. Burton, P. Dolan,Churchill Livingstone, New York, 2002, 238pp, ISBN: 0443 06207 2

The challenge addressed by this book is to identify acomponent of the huge problem of back pain—the partthat is or is thought to be biomechanics. The introduc-tion in fact lays out a carefully framed argument why itis appropriate to identify the specific contributions ofbiomechanics relative to other factors such as inheri-tance of risk factor traits that may predispose to backpain. The intended readership is explicitly stated asthose who treat people with back pain, as well asstudents, ergonomists, and those involved in personalinjury litigation. Combined with the fact that thebiomechanical content is quite simplified, this meansthat if you read the Journal of Biomechanics, you wouldlikely not read this book for its biomechanical content.However, you might recommend it to colleagues orstudents. This book is a brave attempt to consolidateavailable information into a coordinated scientificthesis, leading to practical advise for people who takeon the daily challenge of managing this hugely challen-ging social, clinical, legal, as well as biomechanicalproblem.

Roughly, the first-half of the book presents functionalanatomy, including some detail on the possible sourcesof biomechanically provoked pain, by considering theinnervation of various tissues, as well as estimating theforces and deformations normally imposed on thosetissues. For me, some sections appeared to be overlysimplified. These included a disappointing treatment of

muscle recruitment strategies and the biomechanics ofspinal stability. In reading the section on muscularanatomy, I was left with unanswered questions: Why arethere so many muscles? What do they all do and whendo they do it? Further, the treatment of basic conceptsof spinal stiffness and flexibility seemed unsatisfactory.These topics which ought to be fundamental to spinalbiomechanics barely feature in the index.

Roughly, the second-half of the book takes on thechallenge to understand the possible biomechanicalreasons why people get back pain, and how to applythis understanding practically. While this part of thebook is replete with quantitative information, theinterpretation of these facts is primarily qualitativeand descriptive, leaving this reader less than convincedthat the presented interpretations are correct, or at leastthe most probable ones. These sections also seemed tostray quite often from the declared intent to focus juston the biomechanical aspects. The final part of the bookoffers practical advise for patients, physicians and otherswho take care of patients with back pain, and for thoseinvolved in litigation. The bibliography is huge andcomprehensive—886 references. A Medline search on‘biomechanics back pain’ yields only about twice thisnumber.

The authors have been trained in a broad range ofdisciplines including biomechanics, anatomy, physiol-ogy and epidemiology, and have been major contribu-tors to the literature on back pain, trunk biomechanicsand spinal biomechanics. Together they appear to havecollaborated with an enviable degree of concordance ofopinions, and without any noticeable disconnectionsbetween chapters or sections. A pervasive theme is the

Book reviews / Journal of Biomechanics 36 (2003) 147–150148

authors’ contention that a ‘race’ exists between twoprocesses: the accumulation of tissue damage, and thebiological response to repair that damage. When thisequation gets out of balance, degeneration follows.Then, pain likely follows degeneration. Much of thepractical advise is based on two ideas: (1) that certainpostures and loading regimens encourage transport ofnutrients and metabolites through the intervertebraldisc, and (2) that the time course of mechanicallystimulated tissue remodelling is different for differenttissues; consequently short-term exercise-induced in-creases in muscle strength may outpace the capacity ofbones and ligaments to tolerate the increased loading.

Is this construct credible? The authors admit to amajor problem here, in that despite the increasing

numbers of scientific papers written on back pain andbiomechanics in recent years, the reported prevalence ofthis problem has concurrently increased. Clearly, this isa case where a correlation does not necessarily implycausation. If the correct interpretation is that the newinformation and understanding has not yet been putinto practice, then this book could be a part of theremedy. If not, then much work remains to be done.Either way, this book helps to place the challengessquarely in front of us.

Ian StokesDepartment of Orthopaedics and Rehabilitation,

University of Vermont, Burlington, VT 05405-0084, USA

E-mail address: ian.stokes@uvm.edu

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Cells, gels and the engines of life

Gerald H. Pollack; Ebner & Sons, Seattle WA, 2001, pp.320, Hardback: ISBN 0-9626895-1-3; Paperback: ISBN0-9626895-2-1

Gells, Gels and the Engines of Life is penetrating theestablished field of cell biology and is the book to havefor all readers interested in following new concepts anddiscussions within this field. As the subtitle suggestsGerald Pollack’s goal is to provide ‘‘a new, unifyingapproach to cell function’’. Currently, the cell isconsidered to be an aqueous solution with solutes andorganelles, surrounded by a semi-permeable membrane.Since the discovery of the cell in the early 19th centurycell biologists have tried to fit in many cellular featuresand functions within this model, thereby making themodel immensely complicated. In particular the cellmembrane was constantly extended with numerousspecialised receptors, pumps and channels to explain avariety of cellular functions like homeostasis andcommunication with the environment.

In Pollack’s opinion, cell biology has become socomplicated because scientists are building on the wrongconcept. In Section I of his book he tries to falsify thisconcept by questioning the underlying mechanisms ofvery basic and well-established features we all havewondered about. His argumentation focuses on aspectssuch as why small solutes need particular channels ifthey could easily pass channels for much larger solutes;how the cell could handle all the energy-consumingprocesses, given that it can hardly produce enoughenergy for its sodium pumping only; and how one couldstudy cell physiology with microelectrodes, electropora-tion or patch clamps, given that such techniques disruptover 20% of the cell membrane.

Pollack’s answer is a new, almost simple model of thecell based on the well-known fact that cells are gels andnot aqueous solutions. Gels are polymer matrices thatcan trap large quantities of water and the behaviour andproperties of gels seem to surprisingly well explain themost fundamental aspects of cellular functioning. Tomake this concept likely Pollack explores the basiccontents of a cell (proteins, ions and water) andevaluates how these would theoretically interact. Heconcentrates on the organisation of water in thepresence of regularly charged surfaces, being theproteins in cells. This is the most crucial element in histheory and results in the hypothesis that cells are massesof proteins surrounded by layers of water. Althoughsuch a highly structured water phase is well known inseveral non-biological disciplines, it is at first hard toenvision that structured water could actually be the corecontent of a cell. Despite all assumptions and estima-tions Pollack needs to make his hypothesis plausible, healso provides substantial facts and details about theorganisation of both proteins and cellular water tosupport his theory. In the end, he estimates that onlytwo or three layers of water per protein are needed to filla cell with structured water.

The benefits of the model become clear in Section IIwhere the most basic features of cell physiology areconsidered. Here it is explained that partitioning ofsolutes and ions between the inside and outside of thecell does not depend on an extremely selective and activecell membrane but is directly explainable from the gel-like properties of the cytoplasm. Without the need ofmembrane pumps such partitioning requires zeroenergy. The ion partitioning in combination with thenegatively charged nature of the proteins in the cellaccounts for the cell’s negative electrical potential.

Book reviews / Journal of Biomechanics 36 (2003) 147–150 149