Changing practice in the consideration of fatigue as an aetiological factor for injury.
Submitting InstitutionEdge Hill University
Unit of AssessmentSport and Exercise Sciences, Leisure and Tourism
Summary Impact TypeSocietal
Research Subject Area(s)
Medical and Health Sciences: Clinical Sciences, Human Movement and Sports Science, Public Health and Health Services
Summary of the impact
The impact of this research has been evident in a change of practice
regarding the consideration of fatigue in musculoskeletal profiling, and
as an aetiological risk factor for injury. This change in practice is
evidenced across a range of user groups, influencing evidence-based
practice in both the clinical and sporting context. The body of research
has generated a shift in the consideration of fatigue with regards
sporting injury incidence. Postgraduate teaching has evolved to consider
injury prevention strategies in relation to fatigue, and Governing Body
injury audits have cited this research in working toward injury prevention
The research underpinning this case study was undertaken by Greig. Greig
joined Edge Hill University as a Lecturer in Sport and Exercise
Biomechanics in April 2008. He has been employed continuously throughout
the assessment period and is currently a Reader in Sport and Exercise
Biomechanics in the Department of Sport and Physical Activity. The
underpinning research was undertaken at Edge Hill between 2008 and 2010.
Injury audits by English and European football governing bodies have
highlighted fatigue as a risk factor for injury in professional football.
The interpretation is consistently a lack of physiological conditioning.
This case study is based on a biomechanical consideration of fatigue as an
aetiological risk factor.
Greig has developed a treadmill representation of the physical demands of
match-play, showing that the mechanical response to soccer-specific
exercise mirrors the epidemiological pattern of injury incidence. This
exercise model has been used to conduct a series of studies investigating
the influence of fatigue on biomechanical markers of injury.
Key Finding 1 (Output #1): Eccentric hamstring strength (as measured
using isokinetic dynamometry) is impaired with soccer-specific fatigue,
particularly at high speeds. The time history of changes in hamstring
strength is in line with the incidence and mechanism of hamstring strain
Key Finding 2 (Output #2): Acknowledging that isokinetic strength has
limited kinesiological relation to soccer-specific activities, a kinematic
analysis of agility sprinting was conducted using the same fatigue
protocol. Agility, and in particular cutting, is both a high risk movement
and functionally relevant to the observed changes in hamstring strength. A
fatigue effect was evident in both knee flexion and varus, increasing the
risk of injury.
The consideration of fatigue as a risk factor for injury was continued
next by a PhD student (Small) supervised by Greig. This body of work
further developed the exercise model of fatigue by creating a free-running
Key Finding 3 (Output #3): Acknowledging the limitations of treadmill
protocols in replicating the functional activities inherent in soccer, a
free-running protocol is presented which replicates the physical demands
of match-play. Sprinting is a primary non-contact injury mechanism, and
functionally related to hamstring strain injury which is a primary injury
type. This study showed that fatigue induced technical changes in
sprinting technique, with implications for injury.
Key Finding 4 (Output #4): The free-running protocol was shown to produce
a similar magnitude decrease in eccentric hamstring strength as the
treadmill protocol used previously. Again the changes in eccentric
hamstring strength mirror epidemiological observations of injury
incidence. The isokinetic dynamometry analysis was extended to consider
functional changes in the strength-angle relationship, given the observed
changes in running techniques. Fatigue was shown to influence both peak
strength, and the angle of peak strength.
Research into fatigue as an aetiological factor for injury has continued,
with Greig developing a body of work considering varied injury mechanisms.
The consideration of fatigue has evolved from treadmill to free-running,
and subsequently to repeated trials to reflect the impact of fixture
congestion on the modern professional. PhD students currently supervised
by Greig are investigating the physical response to soccer-specific
exercise in the heat (as a precursor to World Cups in Rio and Qatar), and
the development of injury prevention strategies to develop "fatigability".
Injury epidemiology in similar intermittent team sports (supervised by
Greig at M-Level) is being used to develop a research strategy considering
whether a change in policy might be more effective than any
musculo-skeletal intervention. Greig was recently asked to write a chapter
entitled "Environmental factors for fatigue and injury in professional
football" for the Routledge Handbook of Sport & Exercise.
References to the research
1. Journal Article: Greig, M. and Siegler, J. (2009).
Soccer specific fatigue decreases eccentric hamstring strength. Journal
of Athletic Training, 44(2), 180-184. (Output in REF2).
ISI Web of Knowledge for Sport Sciences, Ranked 35th of 84 on Impact
Factor = 1.68, 5 Yr IF = 3.11, Article Influence Score = 0.96 (Ranked in
Top 10 for AIS), cited by 43
2. Journal Article: Greig, M.P. (2009). The influence of
soccer-specific activity on the kinematics of an agility sprint. European
Journal of Sports Science, 9(1), 23-33. (Output in REF2).
ISI Web of Knowledge for Sport Sciences, Ranked 48 of 84 on Impact
Factor = 1.15, 5 Yr IF = 1.34, Article Influence Score = 0.36; cited by
3. Journal Article: Small, K., McNaughton, L., Greig, M.,
Lohkamp, M. and Lovell, R. (2009). Soccer fatigue, sprinting and hamstring
injury risk. International Journal of Sports Medicine, 30,
573-578. (Output in REF2).
ISI Web of Knowledge for Sport Sciences, Ranked 18 of 84 on Impact
Factor = 2.27, 5 Yr IF = 2.87, Article Influence Score = 0.55 (Ranked in
Top 10 for Eigenfactor Score), cited by 25
4. Journal Article: Small, K., McNaughton, L., Greig, M.
and Lovell, R. (2010). The effects of multidirectional soccer-specific
fatigue on markers of hamstring injury risk. Journal of Science &
Medicine in Sport, 13(1), 120-125. (Output in REF2).
ISI Web of Knowledge for Sport Sciences, Ranked 10 of 84 on Impact
Factor = 2.90, 5 Yr IF = 1.34, Article Influence Score = 0.85 (Ranked in
Top 20 for Eigenfactor Score), cited by 46
5. Journal Article: Small, K., McNaughton, L., Greig, M.
and Lovell, R. (2009). Effect of timing of eccentric hamstring
strengthening exercises during soccer training: implications for muscle
fatigability. Journal of Strength and Conditioning Research,
ISI Web of Knowledge for Sport Sciences, Ranked 31 of 84 on Impact
Factor = 1.80, 5 Yr IF = 2.27, Article Influence Score = 0.41 (Ranked in
Top 10 for Eigenfactor Score) cited by 17
6. Journal Article: Greig, M., Johnson, C. and McNaughton,
L. (2013). Environmental factors for fatigue and injury in professional
football. In Y. Hong (Ed.) Routledge Handbook of Sport & Exercise.
Details of the impact
The following impacts arose between January 2008 and July 2013.
1) Changing practice by sports scientists and sports medicine
practitioners in the consideration of fatigue as an aetiological risk
factor for injury; highlighting the influence of fatigue on markers of
injury, and in conducting musculoskeletal profiling and/or implementing
injury prevention strategies post-exercise. Evidence-based-practice is
paramount to practitioners across a number of user groups, to include
sports scientists, physiotherapists, and medics. This change in practice
has been evident in both clinical settings and professional football, as
detailed below (KF 1-4).
Clinical Practice: Physiotherapists and medical practitioners have
amended practice to acknowledge the influence of fatigue as an
aetiological factor for injury. In 2013, Greig was invited by IPRS
Mediquipe to deliver a key-note presentation entitled "Fatigue and
isokinetics in football" to a delegation including clinicians,
physiotherapists, sports scientists and practitioners from elite sport.
Physiotherapists and clinicians were subsequently given the opportunity to
discuss the practical implications of fatigue profiling with Greig and the
distributors of the isokinetic dynamometer used in the research.
Isokinetic profiles are typically conducted at rest. Greig's research has
highlighted a 20% deficit post-fatigue, and clinically this magnitude of
change would be "red-flagged" for intervention. Thus medical practitioners
from private health institutions and elite sport have expanded the scope
of isokinetic profiling to consider fatigue (Sources 1 and 2, Section 5).
The most contemporary version of the isokinetic dynamometer, Biodex System
4, has recently been amended to add a fatigue component in the Biofeedback
mode. This component has the ability to enable the clinician to select the
desired percentage of fatigue (Source 1. Section 5).
Professional Football: Given the sport-specific focus of the research to
date, the change in practice has been most evident in football. Over the
last 6 years Greig has worked with the Football Association to provide
sports science support to the development squads, primarily the U16 and
U19 England teams. His research has influenced his own practice as a
sports scientist. Players benefit from direct input in post-exercise
prehabilitation programmes. As a sports scientist with the England squads
Greig has worked with a physiotherapist, team Doctor, and coaching staff.
These colleagues assist in the delivery of the interventions and are
thereby also attaining new skills. Indirectly, through advisory groups and
conference attendance, sports scientists at professional clubs are
provided with professional development by the Football Association (Source
4, Section 5).
2) Injury prevention policy
This body of research undertaken by Greig considers the influence of
fatigue as a biomechanical, rather than physiological, concern when
evaluating injury risk and has been cited recently in the injury audit
reports produced by UEFA (Risk Factors for Lower Extremity Muscle Injury
in Professional Soccer: The UEFA Injury Study. Am J Sports Med
2013) and in contemporary reviews of injury prevention strategies
(Hamstring Strain Injuries. Sports Med 2012; Hamstring injuries:
are we heading in the right direction? Br J Sports Med 2012; Risk
factors for hamstring muscle strain injury in sport: a systematic review
and meta-analysis Br J Sports Med 2013).
Working toward REF2020 this body of work is evolving to consider
prehabilitation strategies and policy change driven by observations in
other intermittent team sports. The cumulative impact of sport-specific
exposure over a career in elite sport is also being investigated, with
implications for the care and rehabilitation of retired players. In a
follow-up of the UEFA Champions League study, the impact of cumulative
fatigue was considered in relation to fixture congestion (Source 5). The
UEFA recommendation was to consider the design of match schedules to
ensure recovery between games and minimise the impact of fatigue on
injury. PhD work currently on-going under the supervision of Greig is
considering the replication of tournament demands, using repeated bouts of
the laboratory protocol.
Sources to corroborate the impact
Corroboration is provided by the following individuals:
1) Clinical Education Manager, Biodex (contactable) — to corroborate the
change in medical systems to incorporate fatigue as a clinical factor when
assessing and rehabilitating clients. The Biodex System 4 isokinetic
dynamometer has been updated to include a software amendment which enables
the practitioner to pre-select a desired level of fatigue.
2) Medical Practitioner, Harley St, Formerly of Chelsea FC (Factual
Statement) — To corroborate the transferability of football-specific
research into a sport and exercise setting, and further transcending sport
into general medical practice.
3) Sports Physician at English Institute of Sport (Factual Statement) —
To corroborate the impact of applied sports science research on medical
practice in football, and across sports medicine practice more generally.
4) Head of Sports Science, The Football Association (Factual Statement) —
To corroborate the involvement as a sports scientist with the FA, and the
impact of this research on elite player development and coach education,
and the evidence-based practice in football science.
5) Bengtsson, H., Ekstrand, J., Hägglund, M. (2013). Muscle injury rates
in professional football increase with fixture congestion: an 11-year
follow-up of the UEFA Champions League injury study. Br J Sports Med,
47(12):743-7. doi: 10.1136/bjsports-2013-092383.