Textbook of Sports MedicineBasic Science and Clinical Aspects of Sports Injury and Physical Activity

BlackwellScience

Edited byMichael Kjær, Michael KrogsgaardPeter Magnusson, Lars EngebretsenHarald Roos,Timo TakalaSavio L-Y Woo

Textbook of Sports Medicine

Textbook of Sports MedicineBasic Science and Clinical Aspects of Sports Injury and Physical Activity

BlackwellScience

Edited byMichael Kjær, Michael KrogsgaardPeter Magnusson, Lars EngebretsenHarald Roos,Timo TakalaSavio L-Y Woo

© by Blackwell Science Ltda Blackwell Publishing companyBlackwell Science, Inc., Main Street, Malden, Massachusetts -, USABlackwell Publishing Ltd, Garsington Road, Oxford, Ox DQBlackwell Science Asia Pty Ltd, Swanston Street, Carlton South, Victoria , AustraliaBlackwell Wissenschafts Verlag, Kurfürstendamm , Berlin, Germany

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Contents

Editors and Contributors, ix

Preface, xv

Introduction,

Part 1: Basic Science of Physical Activity and Sports Injuries: Principles of Training

. Cardiovascular and respiratory aspects of exercise — endurance training,

Sigmund B. Strømme, Robert Boushel, Bjørn Ekblom, Heikki Huikuri, Mikko P. Tulppo & Norman L. Jones

. Metabolism during exercise — energy expenditure and hormonal changes,

Jan Henriksson & Kent Sahlin

. Skeletal muscle: physiology, training and repair after injury,

Michael Kjær, Hannu Kalimo & Bengt Saltin

. Neuromuscular aspects of exercise — adaptive responses evoked by strength training,

Per Aagaard & Alf Thorstensson

. Biomechanics of locomotion,

Erik B. Simonsen & Paavo V. Komi

. Connective tissue in ligaments, tendon and muscle: physiology and repair, and musculoskeletal flexibility,

Peter Magnusson, Timo Takala, Steven D. Abramowitch, John C. Loh & Savio L.-Y. Woo

. Cartilage tissue — loading and overloading,

Karola Messner, Jack Lewis, Ted Oegema & Heikki J. Helminen

. Bone tissue — bone training,

Peter Schwarz, Erik Fink Eriksen & Kim Thorsen

Part 2: Aspects of Human Performance

. Recovery after training — inflammation, metabolism, tissue repair and overtraining,

Jan Fridén, Richard L. Lieber, Mark Hargreaves & Axel Urhausen

. Principles of rehabilitation following sports injuries: sports-specific performance testing,

Malachy McHugh, Jens Bangsbo & Jan Lexell

v

vi Contents

. Physical activity and environment,

Peter Bärtsch, Bodil Nielsen Johannsen & Juhani Leppäluoto

. Nutrition and fluid intake with training,

Leif Hambræus, Stefan Branth & Anne Raben

. Ergogenic aids (doping) and phamacological injury treatment,

Ulrich Fredberg, Timo Säppälä, Rasmus Damsgaard & Michael Kjær

Part 3: Physical activity: Health Achievements vs. Sports Injury

. Epidemiology and prevention of sports injuries,

Roald Bahr, Pekka Kannus & Willem van Mechelen

. Exercise as disease prevention,

Ilkka Vuori & Lars Bo Andersen

. Physical activity in the elderly,

Stephen Harridge & Harri Suominen

. Exercise in healthy and chronically diseased children,

Helge Hebestreit, Oded Bar-Or & Jørn Müller

. Disabled individuals and exercise,

Fin Biering-Sørensen & Nils Hjeltnes

Part 4: Exercise in Acute and Chronic Medical Diseases

. Cardiovascular and peripheral vessel diseases,

Mats Jensen-Urstad & Kerstin Jensen-Urstad

. Exercise and infectious diseases,

Bente Klarlund Pedersen, Göran Friman & Lars Wesslén

. Osteoarthritis,

L. Stefan Lohmander & Harald P. Roos

. Exercise in the treatment of type and diabetes,

Hannele Yki-Järvinen & Flemming Dela

. Asthma and chronic airway disease,

Malcolm Sue-Chu & Leif Bjermer

. Amenorrhea, osteoporosis, and eating disorders in athletes,

Michelle P. Warren, Jorun Sundgot-Borgen & Joanna L. Fried

Contents vii

. Physical activity and obesity,

Pertti Mustajoki, Per Björntorp & Arne Astrup

. Gastrointestinal considerations,

Frank Moses

Part 5: Imaging in Sports Medicine

. Imaging of sports injuries,

Inge-Lis Kanstrup, Hollis G. Potter & Wayne Gibbon

Part 6: Sports Injury: Regional Considerations. Diagnosis and Treatment

. Lower leg, ankle and foot,

Jon Karlsson, Christer Rolf & Sajkari Orava

. Knee,

Lars Engebretsen, Thomas Muellner, Robert LaPrade, Fred Wentorf, Rana Tariq, James H.-C. Wang, David Stone & Savio L.-Y. Woo

. Hip, groin and pelvis,

Per Hölmich, Per A.F.H. Renström & Tönu Saartok

. Head,

Liying Zhang, King H. Yang, Albert I. King & Lars Engebretsen

. Spine,

Jens Ivar Brox

. Shoulder,

Michael R. Krogsgaard, Richard E. Debski, Rolf Norlin & Lena Rydqvist

. Elbow, wrist and hand,

Nicholas B. Bruggeman, Scott P. Steinmann, William P. Cooney & Michael R. Krogsgaard

. Practical sports medicine,

Sverre Mæhlum, Henning Langberg & Inggard Lereim

. Multiple Choice Answers,

Index,

Editors and Contributors

Per Aagaard Team Denmark Test Center, Sports Medicine Research Unit, University of Copenhagen, BispebjergHospital, Copenhagen, DK-N, Denmark

Steven Abramowitch Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pitts-burgh Medical Center, Pittsburgh, PA , USA

Lars Bo Anderson Institute of Exercise and Sports Science, University of Copenhagen, DK-N, Denmark

Arne Astrup Research Department of Human Nutrition, Royal Veterinarian and Agricultural University, DK-F, Frederiksberg, Denmark

Roald Bahr The Norwegian University of Sport and Physical Education, Oslo, N-, Norway

Jens Bangsbo Laboratory for Human Physiology, August Krogh Institute, University of Copenhagen, DK-Ø,Denmark

Oded Bar-Or Children’s Exercise and Nutrition Centre, McMaster University, West Hamilton, Ontario, CAN-L L, Canada

Peter Bärtsch Division of Sports Medicine, Department of Internal Medicine, University of Heidelberg, DE-,Heidelberg, Germany

Fin Biering-Sørensen Clinic for Spinal Cord Injuries, Rigshospitalet, University of Copenhagen, DK-Ø,Denmark

Leif Bjermer Department of Lung Medicine, University Hospital, Norwegian University of Science and Technol-ogy, Trondheim, N-, Norway

Per Björntorp Department of Heart and Lung Diseases, University of Gothenburg, Sahlgrenska Hospital, SE-

, Sweden

Robert Boushel Department of Exercise Science, Concordia University, Montreal, Quebec, CAN-HB R,Canada

Stefan Brauth Department of Medical Sciences, Uppsala University Hospital, SE-, Sweden

Jens Ivar Brox Department of Orthopaedics, Section for Physical Medicine and Rehabilitation, Rikshhospitalet,Oslo, N-, Norway

Nicholas Bruggeman Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN , USA

William P. Cooney Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN , USA

Rasmus Damsgaard Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen, DK-Ø, Denmark

Richard E. Debski Musculoskeletal Research Center, University of Pittsburgh Medical Center, Pittsburgh, PA, USA

Flemming Dela Department of Medical Physiology, Panum Institute, University of Copenhagen, DK-N,Denmark

ix

x Editors and Contributors

Bjorn Ekblom Department of Physiology and Pharmacology, Karolinska Institute, University of Stockholm, SE-, Sweden

Lars Engebretsen Department of Orthopaedic Surgery, University of Oslo, Ullevål Hospital, NO-, Norway

Erik Fink Eriksen Department of Endocrinology, Aarlus University Hospital, DK-C, Denmark

Ulrich Fredberg Department of Medicine, Silkeborg Central Hospital, DK-, Denmark

Jan Fridén Department of Hand Surgery, Sahlgrenska University Hospital, SE-, Göteborg, Sweden

Joanna L. Fried Department of Obstetrics and Gynaecology, Columbia University, New York, NY , USA

Göran Friman Department of Medical Services, Section of Infectious Diseases, Uppsala University Hospital, SE-, Sweden

Wayne Gibbon Department of Sports Medicine, University of Leeds, LS NL, UK

Leif Hambraeus Department of Medical Sciences, Nutrition Unit, Uppsala University, SE-, Sweden

Mark Hargreaves Department of Exercise Physiology, School of Health Sciences, Deakin University, Burwood,AUS-, Australia

Steve Harridge Department of Physiology, Royal Free & University College Medical School, London, NW PF,UK

Helge Hebestreit Pneumologie/Sportsmedizin, Universitäts-Kinderklinik, Würzburg, DE-, Germany

Heikki Helminen Department of Anatomy, University of Kuopio, FIN-, Finland

Jan Henriksson Department of Physiology and Pharmacology, Karolinska Institute, University of Stockholm, SE-, Sweden

Nils Hjeltness Department of Spinal Cord Injury, Sunnaas Hospital, Nesoddtangen, Norway

Per Hölmich Department of Orthopaedic Surgery, Amager Hospital, University of Copenhagen, DK-S, Denmark

Heikki V. Huikuri Department of Medicine, Division of Cardiology, University of Oulo, FIN-, Finland

Kerstin Jensen-Urstad Department of Clinical Physiology, Karolinska Hospital, Stockholm, SE-, Sweden

Mats Jensen-Urstad Department of Cardiology, Karolinska Hospital, Stockholm, SE-, Sweden

Norman L. Jones Department of Medicine, McMaster University, Hamilton, Ontario, CAN-LN Z, Canada

Hannu Kalimo Department of Pathology, Turko University Hospital, Turko, FIN-, Finland

Pekha Kannus Accident and Trauma Research Center, UKK Institute, Tampere, FIN-, Finland

Inge-Lis Kanstrup Department of Clinical Physiology, Herlev Hospital, University of Copenhagen, DK-,Denmark

Jon Karlsson Department of Orthopaedics, Sahlgrenska University Hospital/Östra, Gothenburg, SE-,Sweden

Albert I. King Bioengineering Center, Wayne State University, Detroit, MI , USA

Editors and Contributors xi

Michael Kjær Sports Medicine Research Center, University of Copenhagen, Bispebjerg Hospital, Copenhagen,DK- NV, Denmark

Pavo Komi Department of Biology of Physical Activity, University of Jyväskylä, FIN-, Finland

Michael Krogsgaard Department of Orthopaedic Surgery, Bispebjerg Hospital, University of Copenhagen, DK- NV, Denmark

Henning Langberg Sports Medicine Research Unit, Bispebjerg Hospital, Copenhagen, DK- NV, Denmark

Robert F. La Prada, Sports Medicine and Shoulder Divisions, Department of Orthopaedic Surgery, University ofMinnesota, MN , USA

Juhani Leppäluoto Department of Physiology, University of Oulo, FIN-, Finland

Ingard Lerein Department of Orthopaedic Surgery, Region Hospital of Trondhjem, NO-, Norway

Jack Lens Department of Orthopaedic Surgery, University of Minnesota, MN , USA

Jan Lexell Brain Injury Unit, Neuromuscular Research Laboratory, Department of Rehabilitation, Lund Univer-sity Hospital, SE-, Sweden

Richard L. Lieber Department of Orthopaedics and Bioengineering, University of California and V.A. MedicalCenter, La Jolla, CA -, USA

John C. Loh Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh Med-ical Center, Pittsburgh, PA , USA

Stefan Lohmander Department of Orthopaedics, University Hospital, Lund, SE-, Sweden

Sverre Mæhlum Norsk Idrettsmedisinsk Institutt (NIMI), University of Oslo, NO-, Norway

Peter Magnusson Team Denmark Test Center, Sports Medicine Research Unit, University of Copenhagen, Bispe-bjerg Hospital, Copenhagen, DK- NV, Denmark

Willem van Mechelen Department of Social Medicine, Vreie Universität, Amsterdam, NL-, The Netherlands

Karola Messner Department of Neuroscience and Locomotion, Division of Sports Medicine, Faculty of Health Sci-ences, Linköping, SE-, Sweden

Malachy McHugh Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, New York,NY , USA

Frank Moses Gastroenterology Service, Walter Reed Army Medical Center, Washington DC, -, USA

Thomas Muellner Department of Orthopaedic Surgery, University of Vienna, Austria

Jørn Müller Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, DK-Ø,Denmark

Pertti Mustajoki Department of Medicine, Helsinki University Central Hospital, FIN-, Finland

Bodil Nielsen Johansen Institute of Exercise and Sports Science, August Krogh Institute, University ofCopenhagen, DK-Ø, Denmark

Rolf Norlin Linköping Medical Center, SE-, Linköping, Sweden

xii Editors and Contributors

Ted Oegena Department of Orthopaedic Surgery, University of Minnesota, MN , USA

Sakari Orava Tohturitalo Hospital, Turka, Fin-, Finland

Bente Klarlund Pedersen Finsencentret, Department of Infectious Diseases, University of Copenhagen, DK-Ø, Denmark

Hollis Potter Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY , USA

Anne Raben Research Department of Human Nutrition, Centre for Advanced Food Studies, Royal Veterinarian andAgricultural University, DK-F, Denmark

Per Renström Section of Sports Medicine, Department of Orthopaedics, Karolinska Hospital, Stockholm, SE-, Sweden

Christer Rolf Centre of Sports Medicine, University of Sheffield, S TA, UK

Harald Roos Department of Orthopaedic Surgery, Helsingborg Hospital, Helsingborg, SE-, Sweden

Lena Rydqvist Linköping Medical Center, SE-, Linköping, Sweden

Kent Sahlin Department of Physiology and Pharmacology, Karolinska Institute, University of Stockholm, SE-, Sweden

Bengt Saltin Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, DK-Ø, Denmark

Tönu Saartok Section of Sports Medicine, Department of Orthopaedics, Karolinski Hospital, Stockholm, SE, Sweden

Peter Schwartz Department of Endocrinology, Rigshospitalet, University of Copenhagen, DK-N, Denmark

Erik Simonsen Institute for Medical Anatomy, Panum Institute, University of Copenhagen, DK-N, Denmark

Scott Steinman Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN , USA

David Stone Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh Med-ical Center, Pittsburgh, PA , USA

Sigmund B. Strømme The Norwegian University of Sport and Physical Education, Oslo, NO-, Norway

Malcolm Sue-Chu Department of Lung Medicine, University Hospital, Norwegian University of Science andTechnology, Trondheim, N-, Norway

Jorun Sundgot-Borgen Norwegian University of Sport and Physical Education, Oslo, NO-, Norway

Harri Snominen Department of Health Sciences, University of Jyväskylä, FIN-, Finland

Timo Säppälä National Public Health Institute, Helsinki, FIN-, Finland

Timo Takala Department of Biology of Physical Activity, University of Jyväskylä, FIN-, Finland

Rana Tariq Department of Radiology, Ulleval University Hospital, Oslo, N-, Norway

Kim Thorsen Department for Sports Medicine, Norrland University Hospital, Umeå University, SE-,Sweden

Alf Thorstensson Department of Sport and Health Sciences, University College of Physical Education andSports, Department of Neuroscience, Karolinska Institute, Stockholm, SE-, Sweden

Editors and Contributors xiii

Mikko P. Tulppo Merikoski Rehabilitation and Research Centre, University of Oulu, FIN-, Finland

Axel Urhausen Institute of Sports and Preventitive Medicine, Department of Clinical Medicine, University ofSaarland, D-, Saarbruecken, Germany

Ilkka Vuori UKK Institute for Health Promotion Research, Tampere, FIN-, Finland

James H.-C. Wang Musculoskeletal Research Center, Department of Orthopaedic Surgery, University ofPittsburgh Medical Center, Pittsburgh, PA , USA

Michelle Warren Department of Obstetrics and Gynaecology, Colombia University, College of Physicians andSurgeons, New York, NY , USA

Fred Wentort Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN , USA

Lars Wesslén Department of Medical Sciences, Section of Infectious Diseases, Uppsala University Hospital, Uppsala, Sweden

Savio L.-Y. Woo Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of PittsburghMedical Center, Pittsburgh, PA , USA

King H. Yang Bioengineering Center, Wayne State University, Detroit, Michigan, MI , USA

Hannele Yki-Järvinen Department of Medicine, University of Helsinki, FIN-, Helsinki, Finland

Liying Zhang Bioengineering Center, Wayne State University, Detroit, Michigan, MI , USA

Preface

In past decades the number of exercising individuals and the area of sports medicine have grown considerably.Sports medicine has developed both in terms of its clinical importance with appropriate diagnosis and adequate re-habilitation following injury as well as its potential role in the promotion of health and prevention of life-style dis-eases in individuals of all ages. Furthermore, lately the medical field has gained improved understanding of the useof physical activity as a treatment modality in patients with a variety of chronic diseases and in rehabilitation afterdisabilities, injuries and diseases. Common to these advancements is the fact that a certain amount of clinical expe-rience has to be coupled with sound research findings, both basic and applied, in order to provide the best possiblerecommendations and treatments for patients and for the population in general.

There is a tradition in Scandinavia for an interaction between exercise physiology and clinical medicine and sur-gery, and it is apparent that both areas have hypotheses, inspiration and possible solutions to offer each other. It istherefore apparent that a textbook on sports medicine must attempt to incorporate all of these aspects to be com-prehensive. A historical or classical reference has been selected as an introduction to each chapter to reflect the im-pact that a specific scientific work has had on that field. Having several authors collaborating on each chapter in thebook ensures both diversity and a degree of consensus in the text, which will hopefully make the book usable as areference book, and as a textbook both at the pre- and postgraduate levels. It has been our goal to address each topicwithin sports medicine in a scientific way, highlighting both where knowledge is well supported by research, as wellas areas where the scientific support is minimal or completely lacking. It is the intention that the book will help thepeople who work clinically within the area of sports medicine in their daily practice, and that it will also provide thebasis for further research activity within all areas of sports medicine. Moreover, we wish to highlight where knowl-edge and methodologies from different, and often distant, areas can interact to create a better understanding of, forexample, the mechanisms behind development of tissue injury and its healing.

The editorial group has been delighted that some of the world’s leading experts have agreed to participate in thisproject, and they have all contributed with informative and very comprehensive chapters. I greatly appreciate theircontribution and that of the editorial group who worked hard on the completion of the book. Additionally, I wishto acknowledge all other contributors who have helped with the practical procedures of this project. Finally, I hopethe reader of this book will share the research dreams, the clinical interest, and the enthusiasm in relation to thesports medicine topics with that of the authors and the entire editorial group.

Michael KjaerCopenhagen, September

xv

The exercising human: an integrated machinePhysiological boundaries have fascinated man for along time, and achievements like climbing up to morethan m above sea level without oxygen supply ordiving down to more than m in water without spe-cial diving equipment are at the limit of what textbookknowledge tells us should be possible for humans.Likewise, athletes continue to set new standards within sports performance, and patients with chronicdiseases master physical tasks of a very challenging nature, like marathon running, that hitherto werethought impossible.

Muscles, tendons and bone are elegantly coupledtogether to provide an efficient system for movement,and together with joint cartilage and ligaments theyallow for physical activity of various kinds. In order toprovide energy to contracting muscles, ventilationoften rises –-fold and cardiac pump function canincrease up to -fold during strenuous exercise in well-trained individuals in the attempt to deliver sufficientoxygen to allow for relevant oxidative processes thatcan be initiated within seconds. In addition, workingskeletal muscles can by training achieve substantial in-creases in their capacity to both store energy and to ex-tract and utilize oxygen. With regards to endurancecapacity, humans are still left with the fact that the sizeof the heart relative to the skeletal muscle is relativelysmall — even in top-class runners — compared to basi-cally all other animal species.

To drive the human machinery, local as well as dis-

tant substrate stores provide fuel for energy combus-tion, allowing for very prolonged exercise bouts. Acontrolled interplay between exercise intensity, energymetabolism and regulatory hormones takes place, andintake of different food stores can cause the muscle toadjust its fuel combustion to a large degree. The initia-tion of signals from motor centers to start voluntarymovement and afferent signals from contracting mus-cle interact to achieve this and several signalling path-ways for circulatory and metabolic control are nowidentified. The brain can make the muscles move, andcan at the same time use substances for fuel that are re-leased from muscle. Furthermore, intake of differentfood sources can cause the muscle to adjust its fuelcombustion to a large degree.

Training can cause major tissue and organ adapta-tion and it is well known that this to a large degree depends upon both genetic and trainable factors(Table). More recent studies on identical twins haveallowed for a discrimination of these two factors in re-lation to exercise and have shown that between and% of the variation in parameters like maximal oxygen uptake or muscle strength are likely to be attributed to genetic factors. Rather than discouragehumans from starting training on this background, it isfascinating to identify factors responsible for trainingimprovements in, for example, muscle tissue. It is evi-dent that contractile force can elicit transcription andtranslation to produce relevant changes in the amountof contractile or mitochondrial proteins, but the un-derlying mechanism in both muscle and connective

IntroductionMICHAEL KJÆR

MICHAEL KROGSGAARD

PETER MAGNUSSON

LARS ENGEBRETSEN

HARALD ROOS

TIMO TAKALA

SAVIO L-Y WOO

Introduction

tissue is not understood. Interestingly, substances arenow being identified (e.g. mitogenactivated protein kinases) where subtypes are differentially activated byeither metabolic stress or by the degree of contractilestress, to cause either increased cell oxidative capacityor muscle cell hypertrophy, respectively. We are there-fore at a point where we can begin to master the study ofthe adaptation of the human body not only to acute ex-ercise, but also to loading and overloading, and this willprovide us with prerequisites for study of the ultimateadaptation potential that the human organism achieves,and thereby better describe also on an individual levelwhy tissue becomes overloaded and injured.

The delicate balance between trainingadaptation and injury —the dilemma of rehabilitationIt is important for the clinician who treats the recre-ational or elite athlete to have a thorough understand-ing of the injury, and also the ability of the affectedtissue to adapt to immobilization, remobilization and

training. One example is the considerable plasticitythat skeletal muscle tissue displays. While strength islost (up to %) rapidly within a few weeks of immobi-lization, it can be regained over the next couple ofmonths, and strength can be augmented up to -foldwith training for extended periods (months/year).Bone loss also (up to %) occurs rapidly within weeksof immobilization and is subsequently regained in thefollowing months of rehabilitation. However, some-what in contrast to muscle, extended training periodshave a relatively modest impact on bone tissue aug-mentation. Connective tissue loss in tendon is alsocomparable to muscle and bone; however, in contrast,its slower metabolism requires perhaps up to

months or more before complete tissue recovery froman injury and subsequent inactivity. Thus, an injurythat demands a limb to be immobilized for a givenlength of time may require different time periods forthe various tissues to return to their preinjury levels.

In this context it is important for the clinician to notethat the cardiovascular system recovers the fastest after

Table The capacity of various tissues and systems, and their ability to adapt to physical activity or inactivity.

Decrease in functionIncrease during single Improvement or maximal load bout of physical activity with training Time required for with 3–4 weeks of

Function ultimate tensile strength (%) adaptation inactivity (%)

Cardiorespiratory Months–yearsVentilation 35-fold 0CO 6-fold 90 40O2 extraction 2–3-fold 25 30VO2 12–18-fold 50–60 40

Muscle metabolism Weeks–monthsGlycogen/fat stores – 100 50Oxidative capacity – 300 40–100

Connective tissue Months–yearsTendon 100 MPa 20 30Ligament 60–100 MPa 20 30Bone 50–200 MPa 5–10 30Cartilage 5–40 MPa 5–10 30

Muscle Months–yearsStrength – 100–200 60Fibre CSAType I – 40 20Type II – 80 30

CO: cardiac output;VO2: whole body oxygen uptake; CSA: cross-sectional area.

Introduction

a period of relative inactivity, which may create adilemma: the athlete wants to take the rehabilitationand training program to new and challenging levels, but the different tissues may not be able to withstand the associated loads, and re-injury or a new so-called ‘overload injury’ may result. Thus, a thorough understanding of how tissues adapt tophysical activity or lack thereof is paramount for theeffective treatment and rehabilitation of the injuredperson.

While acute injury during exercise may intuitivelybe somewhat easy to understand, it may be more chal-lenging to grasp the insidious and frequent ‘overuse’injuries that occur with training. Some important observations in the field of sports medicine have beenmade in recent decades that have improved our under-standing of these injuries. An awareness of the sub-ject’s loading pattern is important, of course. Therecreational athlete who runs km/week may subjecteach lower limb to approximately landings andtake-offs in that time period. In contrast, the long dis-tance runner who runs km/week may subject eachlower limb to approximately landings and take-offs. Clearly, a certain degree of appropriate tissueadaptation has already taken place to withstand thesevastly different loads, but nevertheless, injuries may besustained by both the recreational and elite athlete andtherefore remains an enigma. Interestingly, the weeklyloading of tissue induced by sports participation isequivalent to that established by national authorities as the upper limits for what is tolerable for manuallabour, suggesting that perhaps there is an inherent tissue limitation to loading.

Disadvantageous alignment, like severe pes planusor genu valgus, for example, may be important factorsin determing who can withstand a given loading pat-tern, although such internal factors cannot entirely ex-plain overuse injury. It has become generally acceptedthat it takes appreciable time for tissues like connectivetissue to adapt to a new or increasing demand, even forthe most genetically fortuitous. Therefore, any desiredprogression or change in a training program should begradual. However, more detailed information with re-spect to the training frequency, duration and intensitythat is required to avoid an injury is currently lack-ing, and thus preventative efforts in this respect remaindifficult. At the same time, it is becoming increasingly

appreciated that tissues need restitution periods to ‘adapt’ to the previous bout of physical activity. This is put into practice, for example, by the tri-athletewho loads the cardiovascular system considerably on a daily basis, but stresses the musculo-skeletal system alternately by training either cycling, runningor swimming, which may help to avoid injury. It is during the restitution period that tissues are allowed to recover, or further adapt to an increasing demand by either expanding their quantity or improving theirquality. It is likely that in years to come researchers will furnish new and improved measurement techniques that will yield important detailed informa-tion about tissue adaptation to physical activity andrestitution.

Sports injuries and development oftreatment: from recreational sports to elite athletesIn many situations the transformation from overloadsymptoms to a sports injury is poorly defined and understood. Intensified research in anatomy, bio-chemistry, physiology and mechanisms of tissue adaptation to mechanical loading is needed to providethe basic understanding of overload injury pathogene-sis. Although this in itself represents a paramountchallenge, it seems even more difficult to understandan individual’s disposition for developing symptoms.Why does one individual develop severe Achilles tendon pain in connection with a certain amount ofrunning, while others do not? Why are overhead activ-ities very painful for some athletes but not for others?Why is the functional stability of a cruciate ligamentdeficient knee or a mechanically unstable ankle jointdifferent between persons despite the same activitylevel? Obviously it would be essential to identify theweakest link in each individual case, but knowledge ofthe individual specific factors is very incomplete.Could there be physiologically different levels for initiation of symptoms in different individuals? It is well known that persons with decreased sensory in-puts, for example caused by diabetic polyneuropathy,have a high rate of overload injuries like tendonitis or stress fractures, simply because the natural alarmsystem is out of order. If a physiological difference in,for example, the threshold of sensory inputs exists in otherwise healthy people, the difference between a

Introduction

mechanical load that causes symptoms and one that results in tissue damage would vary from person toperson.

Treatment of sports injuries represents major chal-lenges. First, the aim to reduce symptoms is demandedby the athlete, and several pharmacological treatmentswill work well at rest, but will not provide pain reliefwhen the individual is exercising. Secondly, when surgical treatment is indicated to repair irreversiblechanges of tissues (e.g. rupture of anterior and poste-rior cruciate ligaments of the knee) or to change bio-mechanical inferior or insufficient movement patterns(e.g. multidirectional instability in the shoulder) theprocedures need to be minimally invasive in order toleave the remaining tissue as intact as possible and toallow for a quick regeneration process. Thirdly, the re-habilitation procedures and time allowed for recoverywill be challenged. This is because athletes are eager toreturn to their sports. In this aspect, similarities can bedrawn to occupational and rehabilitation medicine,which aims towards getting the patient back to thefunctional level that is required to perform a certainlabour task.

In contrast to the little which is known about the in-dividual-based factors, there is increasing knowledgeabout injury mechanisms in athletic performance. A number of specific pathological entities have beenrecognized, especially during the past two decades, e.g.secondary impingement and internal impingement ofthe shoulder in overhead athletes. On the basis of rec-ognizing certain common patterns of injury and un-derstanding their pathogenesis, specific treatments —surgical as well as nonsurgical — have been developed.Probably the first injury to be recognized as a specificlesion connected to sports performance was theBankart lesion of the shoulder, described in , andthe way to repair the lesion was obvious once thepathoanatomical background was established. Simi-larly, when the SLAP lesion of the labrum in the shoul-der was described for the first time about years ago,the surgical treatment options could be defined (forfurther details see Chapter 6.5).

Arthroscopy, which was introduced for knee disor-ders back in and developed for the treatment of shoulder, elbow and ankle disorders in the s, has made direct visualization of joint movement andintra-articular structures possible, and has increased

the understanding of many intra-articular sports in-juries. For the individual athlete it has resulted in amuch more specific diagnosis and treatment, and con-sequently rehabilitation has become faster and easierthan after open surgery. Furthermore, the inventionand development of magnetic resonance imaging inthe early s, and the refinement and general avail-ability of ultrasound investigation during the lates, has increased the spectrum of diagnostic toolssignificantly. What still requires specific attention isthe relative use of these para-clinical supplements ascompared with a good clinical examination and judge-ment. There is no doubt that the new ‘machine-tools’,developed to help the sports medicine practitioner,tend to be ‘over-used’ in the initial phase, which isoften followed by a more balanced phase in which it be-comes evident that patient history and clinical exami-nation can never be replaced by para-clinical tools, butthat the latter provides a fruitful supplement in theprocess of diagnosis in sports medicine.

The collection of clinical information on sympto-matic conditions in athletes can lead to identification ofuniform patterns and logically based treatment modal-ities. Series of treated patients can also give informa-tion about the success rate of certain treatments,whereas only randomized studies can identify the besttreatment strategy in a specific condition. Unfortu-nately, there are very few randomized studies in sportsmedicine and especially within traumatology. This isoften due to a high demand for treatment to ensure fastrecovery and return to sports participation, and it isunlikely that more than a small part of the surgical andnonsurgical treatment modalities will ever be evalu-ated by randomized studies. Even though more than anterior cruciate ligament (ACL) reconstructionsare performed every year in the USA, it is unknownwhich treatment strategy is the most advantageous.There are different factors influencing the decision toperform ACL reconstruction: the chance to get back tosports, prevention of secondary meniscus and carti-lage injury, prevention of giving-way or subluxationepisodes, risk for anterior knee pain or other operativecomplications, or timing of surgery. There is no evi-dence for how these factors should be weighted, and itis unknown if routine reconstruction in all patientsshortly after an ACL injury would reduce the risk oflate complications and increase activity level better

Introduction

than a more conservative approach with rehabilitationas primary treatment. It is very important to performrandomized trials at the same time as new treatmentsare introduced, as it is almost impossible to return tosuch studies later.

Most rehabilitation programs are based on individ-ual, clinical experience and theoretical principles. Justas with surgical treatment, evidence is still lacking onthe effect of a number of general treatment principles.Rehabilitation is very costly, and it is desirable withfurther development of evidence-based rehabilitationstrategies.

New technologies will probably influence the treat-ment of sports injuries in the near future. Local avail-ability of growth factors may reduce repair andremodelling time after injury or surgery. Scaffolds canbe used to introduce a specific architecture. These can be taken over by living tissue, and in combinationwith controlled gene expression, injured tissue canpossibly be restored completely. This will contribute toan avoidance of reconstruction with replacement tis-sue and accompanying suboptimal recovery, as well as ensure the absence of scar tissue otherwise seen inrepair.

In the recreational athlete, many overload condi-tions are often self-limiting. Nature’s alarm systemworks: overloading of tissues often results in symp-toms (pain) long before irreversible changes of the tis-sue structures happen. With a gradual reduction ofactivity, symptoms and overloading disappears, andthe athlete can resume normal activity again. Tenniselbow is a good example of this mechanism. Duringone season about % of middle-aged persons per-

forming recreational racquet sports will experiencesymptoms of tennis elbow. The majority of these casesresolve without specific treatment. The interestingphenomenon is, why humans often carry on with exer-cise despite symptoms and signs of overuse. Interest-ingly, inflammatory reactions within and aroundtendons are seen in humans and in a few animal speciesthat are forced to run like race-horses, whereas almostall other species (like mouse, rat or rabbit) do not showsigns of tendinitis or peritendinitis despite strenuousactivity regimens. Elite athletes can be motivated tocontinue peak performance despite pain or othersymptoms, and it can be difficult or impossible for thenatural repair processes to take place. Not enough isknown about tissue repair and rehabilitation to definethe maximum activity in each individual that is com-patible with a full and fast repair.

The boundary between trivial, reversible conditionsand irreversible, disabling injuries still has to be de-fined in many sports. As an example, there is an ongo-ing discussion about the risk for chronic brain damagesin boxing. Furthermore, nearly nothing is knownabout the long-term effect of continued elite sports ac-tivity on degenerative changes in the knee after ACLreconstruction. With this lack of evidence about physical consequences of sports injuries, ethical con-siderations have a central place in advice and planning.The influence of psychological factors such as compe-tition (matches only take up less than % of the activeplaying time in elite handball, more than % of theACL injuries happen there), self-confidence and ac-ceptance of personal limits have to be acknowledgedand further knowledge is warranted.

Table Motivation and needs in different individuals with physical training.

Performance Disease-effect Prevention Guidelines for Tolerable amounts motivation motivation motivation training of training

Patient ++ (function) +++ ++ +++ +Recreational sports + – +++ ++ ++Elite athletes +++ (competition) – (+) +++ +++

The motive for performing physical training can primarily be based upon a wish of increased performance either in sports or in everyday life,or be related to a wish of increased health and disease prevention.All three groups of individuals display an individually varying degree ofwhich for achieving mental well-being in relation to exercise.The tolerable amount of training depends on the ability of the body towithstand loading and varies therefore significantly between athletes and patients, whereas both patients and athletes share a large requestfor specific guidelines in relation to the training they perform.

Introduction

Regular physical training: benefits and drawbacksFor more than years, systematic exercise or sportshave been carried out worldwide, and one can easilyconsider the average individual living today as beingmuch more inactive than they were in the past. It is be-coming more and more scientifically documented thatphysical inactivity is a major risk factor for disease andpremature death, and that the magnitude of this lies onthe level of other risk factors like smoking, obesity ordrinking. Studies have uniformly concluded thatbeing active or beginning physical activity even at anadvanced age, will positively influence risk factors fordevelopment of inactivity-associated diseases. In spiteof the fact that acute training is associated with a tran-sient increased risk of cardiac arrest, taken in the population as a group, as well as the costly treatment ofsports injuries, socio-economic calculation has foundthat, for the recreational athlete, these drawbacks arefar outweighed by the cost-saving benefits of physicaltraining such as lower incidence of diseases, faster hospital recovery after disease in general, as well as alower frequency of infection and time away from workdue to sickness. The field of sports medicine is there-fore facing a major challenge in improving the level of physical activity in the general population, and forsetting up overall guidelines.

Physical training and patients withchronic diseasesAcute and chronic diseases are associated with bothorgan specific manifestations as well as by more gen-eral disturbances in function due to physical inactivityand sometimes even additional hormonal and cytokine-related catabolism. In general, physicaltraining can counteract the general functional distur-bances, and maybe even affect or prevent the primarymanifestations of disease. It is important to note thatthe motivational aspects, as well as the requirementsfor supervision and guidelines, in the patient with apresent disease differ markedly from healthy exercis-ing individuals (Table).

In principle, most diseases can be combined with acertain degree of physical activity, but the amount ofrestrictions put upon the patient differs considerablybetween diseases (Table). Certain diseases have beenshown to be influenced greatly from physical activity

Table Effects of physical training upon different diseases.

Diseases in which physical training will act preventively indisease development and positively upon primary diseasemanifestations

Ischemic heart diseaseRecovery phase of acute myocardial infarctionHypertensionType-2 diabetesObesity (most pronounced with respect to prevention)OsteoporosisAge-related loss of muscle mass (sarcopenia)Osteoarthritis (most likely only the prevention)Back painCancer (prevention of colon and breast cancer)Depression and disturbed sleep patternInfectious diseases (prevention of upper respiratory tract

infection)

Diseases in which moderate or no direct effect can bedemonstrated upon the primary disease manifestations, butwhere exercise will positively affect both health associatedrisk factors and the general disturbances in overall bodyfunction

Peripheral vascular diseases (arterial insufficiency)Type-1 diabetesBronchial asthmaChronic obstructive lung diseaseChronic kidney diseaseMost forms of cancerMost acute and chronic liver diseasesRheumatoid arthritisOrgan transplanted individualsSpinal cord injured individualsMost neurological and mental diseases

Diseases in which much caution has to be taken or whereexercise is to be discouraged, and where physical trainingoften can have a worsening effect upon primary diseasemanifestations or may lead to complications

Myocarditis or perimyocarditisAcute heart conditions (e.g. unstable angina, acute AMI,

uncontrolled arrhythmia or third degree AV-block)Acute infectious diseases associated with fever (e.g. upper

respiratory tract infection)Mononucleosis with manifest splenomegalyAorta stenosis (chronic effect)Acute severe condition of many diseases mentioned above

(e.g. severe hypertension, ketoacidosis in diabetes)Acute episodes of joint swelling (e.g. rheumatoid arthritis) or

severe muscle disease (e.g. myositis)

Introduction

(e.g. ischemic heart disease, type- diabetes), whereasother diseases are known to be relatively insensitive toexercise when it comes to primary disease manifesta-tions (e.g. chronic lung disease, type- diabetes). In thelater group of diseases, it should, however, be notedthat physical training can still have a beneficial effect onhealth-related parameters that can be achieved by indi-viduals in general. This effect is achievable even in theabsence of any worsening of the primary chronic dis-ease. This emphasizes the importance of also encour-aging individuals with chronic (and not necessarilyfatal) diseases to train on a regular basis from a generalhealth perspective. In addition, almost all diseased in-dividuals can exercise in order to counteract the gener-al loss in function that their disease-related inactivityhas caused. In very few cases, extreme caution has to betaken when performing exercise (e.g. acute infectiousdiseases) (Table).

In spite of current knowledge of the effect of physi-cal training on diseases, the exact mechanisms behindthis are still only partially described. To find such bio-

chemical and physiological pathways will be impor-tant not only for addressing which type and dose ofphysical training should be prescribed for the indivi-dual patient, but also for identifying more general ‘health-pathways’ by which muscular contractions caninfluence the health status of the individual. Especiallyin relation to disease, the influence of training on suchpathways either by itself or in combination with phar-maceutical drugs will potentially play a role in treat-ment of disease and maintenance of health into old age.Specific identification of health-related pathways inour genes will furthermore provide insight into the ge-netic polymorphism and help to explain the interindi-vidual variation in training responses and health-related outcome of these. Evidently, this will also openpossibilities for genetic treatment of inherited disor-ders with regards to tissue and organ adaptability totraining, and at the same time inadvertently provide opportunities for misuse of gene therapy in relation to doping, a question that will challenge the sportsmedicine field ethically.

Part 1Basic Science of PhysicalActivity and Sports Injuries:Principles of Training

Classical reference

Krogh, A, Lindhard, J The regulation of respirationand circulation during the initial stages of muscularwork. J Physiol (Lond ) 1913; : –.

This paper demonstrated changes in respiration andheart rate with the transition from rest to bicycle exer-cise. The investigators did experiments on themselves,and Fig. .. shows the changes in tidal air and heartrate at the onset of exercise. As will be noted, a veryrapid increase in both ventilation and heart rate wasobserved, and this led to the conclusion that motorcenter activity in parallel with activation of skeletalmuscle caused an increased stimulation of respiratorycenters as well as the heart. This was called cortical irradiation, and has later been referred to as centralcommand or feed-forward, and has become an impor-tant topic in the discussion of respiratory, circulatory,and hormonal changes during exercise.

Cardiovascular adaptation

Cardiac outputThe pumping capacity of the heart is a critical deter-minant of endurance performance in exercise eventssuch as running, cycling, rowing, swimming, etc.,where a large fraction of total body muscle mass is con-tracting dynamically. Because of the large dependenceon oxidative metabolism for the total energy turnoverin exercise activities sustained for longer than min,

performance level is, as will be discussed later, largelydependent on the capacity for O2 delivery, and thus onthe magnitude of maximal cardiac output.

Maximal aerobic power ( 2 max) is a classic meas-ure of the capacity to perform endurance exercise, andmay be described physiologically as the product ofcardiac output and the extraction of O2 by muscle. Foralmost a century it has been recognized that a linear relationship exists between maximal oxygen uptakeand cardiac output, and this relationship is also observed in other species [–]. It is estimated that–% of the interindividual difference in 2 max isV̇

V̇

Chapter 1.1Cardiovascular and RespiratoryAspects of Exercise —EnduranceTrainingSIGMUND B. STRØMME, ROBERT BOUSHEL,

BJØRN EKBLOM, HEIKKI HUIKURI,

MIKKO P. TULPPO & NORMAN L. JONES

Fig. .. A recording of the tidal air on a spirometer(constructed by Krogh) at rest and at the beginning of exercise.

Chapter .

attributable to the level of maximal cardiac output [].Looked at another way, during whole body exercise,only ~–% of maximal mitochondrial respiratorycapacity is exploited because of the limits of O2delivery [–]. Endurance training augments skeletalmuscle oxidative capacity and O2 extraction, but theprincipal variant for improvements in 2 max is maxi-mal cardiac output [–] (Fig. ..).

On the other hand, differences in athletic perform-ance amongst competitive athletes with similar 2 maxare linked to peripheral mechanisms [], such as running economy. The basic question as to what limitsmaximal aerobic power ( 2 max) will be discussed laterin this chapter.

Cardiac structureThe increase in maximal cardiac output (Q max) follow-ing endurance training results from a larger cardiacstroke volume (SV), whereas maximal heart rate(HRmax) is unchanged or even slightly reduced. Whileheart size is a function of total body size as well as genetic factors, the higher SV achieved by endurancetraining is attributed to enlargement of cardiac cham-ber size and to expansion of total blood volume []. On the basis of cross-sectional studies in both

V̇

V̇

V̇

female and male endurance-trained athletes, totalheart volume is generally –% larger than sedentary size-matched controls, with morphologicdifferences seen in both the ventricles and the atria[]. Chamber enlargement is also observed in en-durance-trained paraplegics compared to sedentarymatched controls [].

There is a close relationship between cardiac volume and physical performance []. However, thecardiac hypertrophy is dependent on the type of sportcarried out. There are two main types of myocardialhypertrophy. In weight lifters and other strength-training athletes heart wall thickness is increased, withonly minor increases in heart cavity diameters, whileendurance athletes have increased heart volume andcavity diameter with a proportional increase in wallmuscle thickness []. The ratio of wall thickness to cavity diameter is unchanged in the endurance-trained individual but increased as a result of strengthtraining [].

The left ventricular hypertrophy in the endurance-trained individual is due to volume overload (‘eccen-tric’ hypertrophy), while the hypertrophy due tostrength training develops as a consequence of pres-sure overload (‘concentric’ hypertrophy). Rowing, for

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VO2max (L /min).

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Fig. .. Relationship between increasesin cardiac output and maximal oxygenuptake in heart failure patients (circles),healthy males after days’ bedrest(squares), the same subjects before bedrest(inverted triangle), the same subjects afterendurance training (upright triangle), andendurance athletes (diamonds).