Single bout of vibration-induced hamstrings fatigue reduces quadriceps inhibition and coactivation of knee muscles after anterior cruciate ligament (ACL) reconstruction.
J Electromyogr Kinesiol
; 55: 102464, 2020 Dec.
Article
in En
| MEDLINE
| ID: mdl-32942109
ABSTRACT
Persistent quadriceps strength deficits in individuals with anterior cruciate ligament reconstruction (ACLr) have been attributed to arthrogenic muscle inhibition (AMI). The purpose of the present study was to investigate the effect of vibration-induced hamstrings fatigue on AMI in patients with ACLr. Eight participants with unilateral ACLr (post-surgery time Mâ¯=â¯46.5, SDâ¯=â¯23.5â¯months; age Mâ¯=â¯21.4, SDâ¯=â¯1.4â¯years) and eight individuals with no previous history of knee injury (age Mâ¯=â¯22.5, SDâ¯=â¯2.5â¯years) were recruited. A fatigue protocol, consisting of 10â¯min of prolonged local hamstrings vibration, was applied to both the ACLr and control groups. The central activation ratio (CAR) of the quadriceps was measured with a superimposed burst of electrical stimulation, and hamstrings/quadriceps coactivation was assessed using electromyography (EMG) during isometric knee extension exercises, both before and after prolonged local vibration. For the ACLr group, the hamstrings strength, measured by a load cell on a purpose-built chair, was significantly (Pâ¯=â¯0.016) reduced about 14.5%, indicating fatigue was actually induced in the hamstrings. At baseline, the ACLr group showed a trend (Pâ¯=â¯0.051) toward a lower quadriceps CAR (Mâ¯=â¯93.2%, SDâ¯=â¯6.2% versus Mâ¯=â¯98.1%, SDâ¯=â¯1.1%) and significantly (Pâ¯=â¯0.001) higher hamstrings/quadriceps coactivation (Mâ¯=â¯15.1%, SDâ¯=â¯6.2% versus Mâ¯=â¯7.5%, SDâ¯=â¯4.0%) during knee extension compared to the control group. The fatigue protocol significantly (Pâ¯=â¯0.001) increased quadriceps CAR (from Mâ¯=â¯93.2%, SDâ¯=â¯6.2% to Mâ¯=â¯97.9%, SDâ¯=â¯2.8%) and significantly (Pâ¯=â¯0.006) decreased hamstrings/quadriceps coactivation during knee extension (from Mâ¯=â¯15.1%, SDâ¯=â¯6.2% to Mâ¯=â¯9.5%, SDâ¯=â¯4.5%) in the ACLr group. In conclusion, vibration-induced hamstrings fatigue can alleviate AMI of the quadriceps in patients with ACLr. This finding has clinical implications in the management of recovery for ACLr patients with quadriceps strength deficits and dysfunction.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Vibration
/
Muscle Fatigue
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Quadriceps Muscle
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Muscle Strength
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Anterior Cruciate Ligament Reconstruction
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Hamstring Muscles
/
Knee Joint
Type of study:
Guideline
Limits:
Adult
/
Female
/
Humans
/
Male
Language:
En
Journal:
J Electromyogr Kinesiol
Journal subject:
FISIOLOGIA
Year:
2020
Document type:
Article
Affiliation country: