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Electromyography in swimming: a literature study
Transcript of Electromyography in swimming: a literature study
May 27th 2013
What is electromyography ?
Standard works in EMG
Surface ElectroMyoGraphy for the Non-Invasive Assessment of Muscles
Search for literature
“... the study of muscle function through the inquiry of the electrical signal the muscle emanates”
first experimental EMG study
evidence for relationship between muscle contraction and electricity
Ikaï et al.
Describe 15 muscle patterns in all 4 strokes
Compare EMG of 9 Olympic swimmers with 5 university team swimmers
"An electromyographic study of swimming"
Res. J. Physical Education
first EMG study in water
only EMG study where there was a concern about electrocution !
first study using telemetry which allowed more freedom of movement for swimmer
"Telemetrical analysis of the electromyogram"
International Congress of Biomechanics I
Milestones in EMG swimming research
Thank you for your attention
Unilateral vs bilateral
Make the plan
first EMG study with normalization in order to compare between swimmers or between the same swimmer in different situations
before only raw or integrated signals
"Quantitative comparison of the electromyogram of the swimmer"
Biomechanics and Medicine in Swimming I
to MVC or not to MVC
MVC : subject does maximal voluntary contraction of all muscles studied
iEMG of MVC is reference value (100%)
+ perfect in all static (e.g. isometric) applications (Clarys 2011)
- for dynamic activities (e.g. swimming) debatable (Clarys 2000, 2002)
dynamic percentages in swimming up to 160% of MVC (Lewillie 1973, Clarys 1983)
- difference in MVC on dry land and in water (Masumoto 2008)
dynamic maximum : normalization to highest peak activity in dynamic conditions
+ counters negatives of MVC
- less internationally accepted (harder to publish)
25 muscles investigated
60 subjects ! 30 elite swimmers and 30 national level swimmers
"The brussels EMG project"
series of studies in the 80's
J.P. Clarys et al.
i = input
g = glide
pl-ph = pull-push
o = output
r = recovery
first fine wire study to investigate (amongst others) rotator cuff muscles
lot of methodological problems :
only 3 subjects willing
3 of 8 leads became inoperable during testing
electrical noise picked up and difficult to filter
"Fine wire electromyography analysis of muscles of the shoulder during swimming"
American J. Of Sports Medicine, 14 (1), p,7-11
G.W. Nuber et al.
Later, other researchers from the Inglewood Biomechanics lab were more successfull with fine wire :
Pink, 1991, The normal shoulder during freestyle swimming
Scovazzo, 1991, The painfull shoulder during freestyle swimming
Pink, 1993, The normal shoulder during butterfly swim stroke
Pink, 1993, The painful shoulder during butterfly swim stroke
Ruwe, 1994, The normal and painfull shoulder during breaststroke
first study using frequency analysis to evaluate fatigue in swimming
7 male international level swimmers swam 4x50 (r 10") ECU and FCU
standing on the shoulders of pioneers in fatigue studies from Lyon
"Time-frequency parameters of wrist muscles EMG after an exhaustive freestyle test"
Biomechanics and Medicine in Swimming X
V. Caty et al.
1st study using wireless technology allowing full freedom of motion
2nd study to describe activation patterns in swimmer with impairment
4th study to analyse EMG bilaterally
pilot study with only raw signal
International Society of Biomechanics in Sports 2011
Which muscles ?
Abdominal and lower back muscles are amongst the least studied muscles in swimming
Literature on lower back injuries in swimmers is sparse
1 study : Kanoeka et al., 2007
Shoulder injuries in swimmers are most prevalent
Kammer et al., 1999 : 55% of all injuries in swimmers
Richardson et al., 1980 : 52% of all elite swimmers (n=137)
Heinlein, 2010 : "Whereas the functional manifestation may present as shoulder pain, the underlying cause may be core weakness."
Relationship between function of shoulder girdle and rest of body well recognized in athletes (Burkhart et al., 2003 throwing; Kibler et al., 2006 tennis), but not experimentally studied in swimmers
difficulty of cross talk
virtually impossible with wired electrodes
Evidence on the role of core stability (during swimming) in injury prevention in swimmers is to the presenters knowledge nonexistent
"... we noticed a significant difference in work intensity in trunk muscles. All these observations stress the importance of correct use and specific training of trunk muscles to improve performance in swimming the front crawl"
Evidence on the role of core stability in improving performance in (able bodied) swimmers does exist
RA 11/65 studies
ES 5/65 studies
OE 2/65 studies
Which population ?
Only 1 study comparing swimmers with physical impairment to able bodied swimmers
No studies on EMG pattern of swimmers with intellectual or visual impairment
De Witte et al., 1988
Aspects of physical functioning
shorter limbs (dworfism)
ability to activate core
end race result
Impairment = SCI
competition outcome = performance
e.g. end race time
Impairment = SCI
determinant of performance :
e.g. ability to activate core muscles
Evidence based classification
"Surface electromyography is more adaptable to global studies on sportsmen and better accepted by subjects" (O'Connell & Gardner, 1963; Spirings et al., 1977)
okt nov dec jan feb mar apr may jun jul aug sep
Trunk muscle activity during front crawl swimming in different populations
prof. D. Daly : promotor
prof. F. Staes : copromotor
prof. R. Fernandes : copromotor
University team swimmer
Olympic team swimmer
n = 65 studies
"The activity of trunk muscles in paraplegic patients after breaststroke initiation"
Biomechanics and Medicine in Swimming V
compare activity of trunk muscles of 4 paraplegic patiens to results from able bodied swimmers (Ikaï, 1964)
most similar patterns for trapezius and latissimus dorsi observed in patient with lowest level of SCI
over the 4 swimmers, similarity in trapezius and rectus abdominus during breaststroke was poor
comparison made between patients in a teaching program and Olympic swimmers
duration of the program not mentioned
only raw signal analysis
"Telemetric system allows more kinesiological freedom to the subject or a movement" (Clarys, 1988)
KINE®, KINE Ltd., Hafnarfjördur, Iceland
input impedance : 10 GΩ
CMRR : 110dB
A/D converter : 10 bit
sensitivity : 4 µV.
weight : 26g
center-to-center inter-electrode distance : 20 mm
transmission carrier frequency : 433.05–434.79 MHz
internal memory : maximal 7 min.
Swimmers with (history) of shoulder injury