39
Rev. Bras. Fisiot. Vol. 2, No. I (1997)
©Associação Brasileira de Fisioterapia
Electromyographic Activity of Vastus Medialis Oblique
Muscle in Step-Up and Step-Down Exercises*
Vanessa Monteiro-Pedro 1, Mathias Vitti2 , Fausto Bérzin 3 , Débora Bevilaqua-Grosso
4
1
Department oj Physiotherapy, Federal University of São Carlos
Via Washington Luís, Km 235, P.O. 676, 13565-905, São Carlos, SP- Brazil- [email protected]
2
Department of Morphological Sciences, College of Dentistry of Ribeirão Preto, University of São Paulo
3
Department de Morphological Sciences, College of Dentistry of Piracicaba, State University of Campinas
4
Department of Physiotherapy, University Methodist of Piracicaba.
Received:31.03.97; Accepted: 12.05.97
Resumo. A proposta deste estudo foi analisar a atividade eletromiográfica do músculo vasto mediai
oblíquo (VMO) nos exercícios de subi~ descer um degrau. A atividade elétrica do músculo VMO foi medida em 15 sujeitos,
saudáveis com idade de 19 a 33 anos, (X= 24,4, SD = 4,1) sem história de patologia no joelho, utilizando um eletromiógrafo
Nicolet de 8 canais e mini eletrodos de superfície tipo Beckman. Os sinais captados foram quantificados em RMS (raiz
quadrada da média) e expressos em microvolts. A análise estatística (ANOV A e Teste de Tukey) foi calculada ao nível de
5% de significância. Os resultados mostraram que a atividade eletromiográfica do músculo VMO foi significativamente
maior no exercício de subir (trabalho concêntrico) do que no de descer (trabalho excêntrico). Estes achados, dentro das
condições experimentais usadas, sugerem que os exercícios de subir e descer um degrau poderiam recuperar a função do
músculo VMO, inicialmente com trabalho excêntrico e, posteriormente, concêntrico.
Palavras-chave: eletromiografia, exercício, reabilitação do joelho
Abstract. The purpose of this study was to determine the electromyographic activity of the vastus medialis
oblique muscle (VMO) during step-up and ste.E_-down exercises. The electrical activity of the VMO muscle was measured
on 15 healthy subjects, aged 19 to 33 years, (X= 24.4, SD = 4.1) with no history ofknee pathology, using a 8 channels
Nicolet Electromyograph and Beckman surface mini electrodes. The signal was recorded in root mean square (RMS),
expressed in microvolts. The statistical analyses (ANOVA and Tukey test) were calculated at 5% of significance. The results
showed that the electromyographic activity of the VMO muscle was significantly greater during the step-up (concentric
work) than in the step-down exercise (eccentric work). These findings, within the experimental conditions used, suggest
that the step-up and step-down exercises could recover the VMO muscle function, initially with eccentric work and
afterwards,with concentric.
Keywords : electromyography, exercise, knee rehabilitation
Introduction
The treatment of severa! pathologies of the knee joint
(such as meniscal , ligament injury and others), including those
of the patellofemoral joint, often include the step-up and stepdown (one or more steps) exercises, in the anterior, posterior or
lateral planes (Malone et al., 1980; Mangine, 1988; Hilyard,
1990; Doucette & Goble, 1992 and Reynolds et al., 1992).
In conservative treatment of the patellofemoral joint disorders, the referred exercises are indicated between the intermediary
and advanced phases (Pevsner et al., 1979; Paulos, 1980; Antich
& Brewster, 1986; Mcconnell, 1986; Shelboume & Nitz, 1990),
with muscle power increasing and pain decreasing (Dehaven, et
al., 1979). However, not many works that have studied the EMG
activity of VMO muscles in these exercises have been found.
Thus, the purpose of this work was to analyze the electromyographic activity of the VMO muscle on step-up and
step-down exercises .
Material and Method
Subjects
The VMO muscle, was analysed electromyographically in
fifteen healthy adul!._volunteers, (five women and ten men),
aged 19 to 33 years (X= 24.2 SD = 4.1), without any history of
skeletal muscle dysfunction at the time they were studied,
* Part of doctoral thesis, presented by Vanessa Monteiro Pedro to College of Dentistry of Piracicaba - State University of Campinas.
*Artigo publicado no Brazilian Journal of Morphological Sciences., n.l, v. 14, p.I9-23, 1997.
40
Monteiro-Pedro et al.
Rev. Bras. Fisiot.
specially in the patellofemoral joint. This condition was established to assure that the volunteer did not show signals and
symptoms that characterize knee and hip pathologies.
Performed exercises
Equipment
Statistical Analysis
Electromyograph
The data were submitted to variance analysis (ANOV A)
with two classification criteria: exercises and volunteers. To
compare medium values, the Tukey's test at 5% significance
levei was used.
Step-up with right lower limb
Step down with right lower limb
The EMG activity was obtained through an 8 channels
electromyograph Viking 11 (Nicolet Biomedical Instruments).
The signals registered were quantified in root mean square
(RMS), expressed in J.l.V using the MV A software package
(Maximal Volunteer Activity).
The calibration of the apparatus varied from 200 to
1000 J.l.V/division. The recording speed was of200 ms/division,
and the filter used was of 10Hz (in low frequency) and 10KHz
(in high frequency).
To register the action potential of the VMO muscle a pair
ofbipolar surface mini electrodes, type Beckman was used, and
the distance between each electrode was of 2 em.
Table 1. Means and Standard Deviations ofEiectromyographic Readings (RMS
in j.tV) ofthe VMO muscle, during step up and step down exercises N = 15.
Step
Exercises
Results
The electromyographic activity of the VMO the muscle
on step-up exercise was significantly greater at 5% levei , than
on the step-down exercise (Tables 1 and 2).
A step with a height of 17 em was used to perform the
exercises.
RMS (flV)
Procedures
Before initiating the tests, a short training period was
provided, with the volunteer performing the exercises under
orientation in order to get used to them.
Following skin preparation (cleansing with alcohol, and
when necessary, hair remova!), a pair of electrodes was fixed 5
em superior and mediai to the superomedial border of the
patella, based on the technique proposed by Hanten & Shulthies
(1990). The right low limb was chosen for being better positioned and nearer to the equipment, which made the performance of the exercises easier.
The volunteer was instructed to concentrate on the verbal
command of Attention now! given by the electromyograph
operator to begin the exercises and ordered to perform them as
naturally as possible, looking for some uniformity in the movement.
For each exercise two contractions were performed and
the mean obtained was used for calculus. The interval between
each contraction was of 15 s, and between each exercise, of
1 min. This time was estimated in order to avoid irregularities
during the performance of the exercises. The volunteer was
instructed to report any possible signal of discomfort or muscle
tiredness to the investigator.
Position
In the step-up exercise, the volunteer was placed with the
distai part of the right foot supported on the step and the left
lower !imb supported on the ground with the heel tumed towards
the step. In the step-down exercise, the volunteer's feet were
supported on the step and when the exerci se was done, he tumed
to the initial position of stepping-up.
Step-up*
Step-down
X
SD
X
SD
135.33
74.43
70.87
29.14
* A significam difference existed between the mean of VMO for the step-up
exerci se.
Table 2. Analysis of variance with two criteria of classification: exercises and
subjects.
Source
df
ss
Subjects
14
60776.20
4341.16
2.12
31169.63
31169.63
15.21*
2049.20
Exercises
Erro r
14
28688.87
Total
29
120634.70
MS
Test
* Statistically significam at 5% levei.
Conclusions
We noticed that the EMG activity ofthe VMO muscle, in the
step-up exercises was significantly greater than on the step-down
ones. Thus, we could recover its function through these exercises,
using initially the eccentric work and !ater the concentric. Besides,
we believe that new works should be petformed in order to verify
not just the influence of these exercises in patellofemoral joint
dysfunctions patients, but also the EMG activity of vastus lateralis
muscle, compared to the VMO activity.
References
1. ANTICH, T.J. & BREWSTER, C.E. -1986- Modification of quadriceps tensoris muscle exercises during
knee rehabilitation. Phys. Ther., 66: 1246-51.
V oi. 2. No. I, 1997
EMG in step- up and step- down exercises
2. DEHA VEN, K.E.; DOLAN, W.A.; MA YER. P.J.1979 - Chondromalacia patellae in athletes: clinicai
presentation and conservative management. Am. J.
Sports Med., 7: 5-1 1.
3. DOUCETTE, S.A. & GOBLE, M. - 1992 - The
effect of exercise on patellar tracking in lateral
patellar compression syndrome. Am. J. Sports Med.,
20: 434-40.
4. HANTEN, W.P. & SCHULTHIES, S.S. -1990 -Exercise effect on electromyographic activity ofthe vastus
medialis oblique and vastus lateralis muscles. Phys
Ther. 7: 561-5.
5. HILYARD, A. - 1990 - Recent developments in the
management of patellofemoral pain: the McConnell
program. Physiotherapy; 76: 559-65.
6. MALONE, T.; BLACKBURN, T.A.; WALLACE,
L.A. - 1980 - Knee rehabilitation. Phys. Ther., 60:
1602-10.
41
7. MANGINE, R.E. - 1988 - Physical therapy of the
knee. New York, Churchill Livingstone.
8. McCONNELL, J.- 1986- The management of chrondormalacia patellae: a long-term solution. Aust. J.
Physioth., 32: 215-23.
9. PAULOS, L.; RUSCHE, K.; JOHNSON, C. NOYSE,
R.F.- 1980- Patellar malalignment: a treatment rationale. Phys. Ther., 60: 1624-32.
10. PEVSNER, D.N.; JOHNSON, J.R.G.; BLAZINA,
M.E. -1979- The patellofemoral joint and its implications in the rehabilitation of the knee. Phys. Ther., 59:
869-74.
11. REYNOLDS, N.L.; WORRELL, J.W.; PERRIN,
D .H. -1992 - Effect of a lateral step-up exerci se pro toco! on quadriceps isokinetic peak torque values and
thigh girth. Phys. Ther., 15: 151-5.
12. SHELBOURNE, K.D. & NITZ, P. -1990- Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am. J. Sports Med., 18: 292-9.