Title: Surface EMG modifications in response to anterior cruciate ligament creep elicited during cyclic exercise Authors & affiliations: Sbriccoli Paola1, Moshe Solomonow1, Bing-He Zhou1 1Occupational Medicine Research Center, Bioengineering Laboratory Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112 Abstract: (Your abstract must use Normal style and must fit in this space) Introduction. Static and cyclic loads applied to various joints during occupational and sport activities can elicit a neuromuscular impairment consisting of changes observed within the electromyographic (EMG) signal, i.e. the presence of random spasms and a decrease in the EMG activity. The hypothesis of this work was that creep developed in the anterior cruciate ligament (ACL) due to cyclic load may have a relevant impact on the reflex activity of the musculature involved as well as on the viscoelastic structures, therefore increasing the risk of injury. This work was therefore aimed to test the effect of creep developed in the ACL on the function of knee flexor and extensors muscles in healthy males and females. Methods. Twelve subjects (six males and six females) participated in the experiment. Force and surface electromyographic (sEMG) signals were recorded from the right quadriceps (RQ) and hamstrings (RH) during maximal voluntary knee flexion (MVCflex) and extension (MVCext) before and after a 10-min cyclic load (frequency: 0.1 Hz) was applied to the proximal tibia with the knee angle fixed at 90 degrees. The peak load imposed during the 10-min cycle was 200 N for males, and 150 N for females. The mean amplitude value (MAV) was computed over each EMG signal. The ACL displacement was also assessed during the 10-min cyclic load. The experimental protocol was repeated after two weeks with the knee angle at 35 degrees. Results. During the 90 degrees experiment, the MVCext decreased significantly (p<0.05) after the 10-min cycle in both males and females; this was associated to a decrease in EMG MAV in both RQ and RH. The mean ACL displacement was significantly (p<0.05) higher in females (8.7 ± 0.8) than in males (7.2 ± 1.2) (p<0.05). Similar results were obtained for the 35 degrees experiment. Frequent EMG spasms were observed within the EMG signal, especially in the RH. No difference for all considered parameters was detected between the two experimental conditions (35 and 90 degrees). Discussion. These results, though preliminary, suggest that sustained cyclic load results in neuromuscular changes that associated with the increased laxity of ACL ligament may increase the risk of ACL injury.
Surface EMG modifications in response to anterior cruciate ligament creep elicited during cyclic exercise.
Sbriccoli P;
2004-01-01
Abstract
Title: Surface EMG modifications in response to anterior cruciate ligament creep elicited during cyclic exercise Authors & affiliations: Sbriccoli Paola1, Moshe Solomonow1, Bing-He Zhou1 1Occupational Medicine Research Center, Bioengineering Laboratory Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112 Abstract: (Your abstract must use Normal style and must fit in this space) Introduction. Static and cyclic loads applied to various joints during occupational and sport activities can elicit a neuromuscular impairment consisting of changes observed within the electromyographic (EMG) signal, i.e. the presence of random spasms and a decrease in the EMG activity. The hypothesis of this work was that creep developed in the anterior cruciate ligament (ACL) due to cyclic load may have a relevant impact on the reflex activity of the musculature involved as well as on the viscoelastic structures, therefore increasing the risk of injury. This work was therefore aimed to test the effect of creep developed in the ACL on the function of knee flexor and extensors muscles in healthy males and females. Methods. Twelve subjects (six males and six females) participated in the experiment. Force and surface electromyographic (sEMG) signals were recorded from the right quadriceps (RQ) and hamstrings (RH) during maximal voluntary knee flexion (MVCflex) and extension (MVCext) before and after a 10-min cyclic load (frequency: 0.1 Hz) was applied to the proximal tibia with the knee angle fixed at 90 degrees. The peak load imposed during the 10-min cycle was 200 N for males, and 150 N for females. The mean amplitude value (MAV) was computed over each EMG signal. The ACL displacement was also assessed during the 10-min cyclic load. The experimental protocol was repeated after two weeks with the knee angle at 35 degrees. Results. During the 90 degrees experiment, the MVCext decreased significantly (p<0.05) after the 10-min cycle in both males and females; this was associated to a decrease in EMG MAV in both RQ and RH. The mean ACL displacement was significantly (p<0.05) higher in females (8.7 ± 0.8) than in males (7.2 ± 1.2) (p<0.05). Similar results were obtained for the 35 degrees experiment. Frequent EMG spasms were observed within the EMG signal, especially in the RH. No difference for all considered parameters was detected between the two experimental conditions (35 and 90 degrees). Discussion. These results, though preliminary, suggest that sustained cyclic load results in neuromuscular changes that associated with the increased laxity of ACL ligament may increase the risk of ACL injury.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
