A Comparison of EMG Activity of Some Lower Extremity Muscles in Individuals with and without Dynamic Knee Malalignment in Single-Leg Squat

Document Type : Research Paper


1 Assistant Professor, Department of Sport Sciences, Faculty of Education and Psychology, Shiraz University, Shiraz, Iran

2 Associate Professor, Department of Sport Injury and Corrective Movement, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran

3 MSc in Sport Psychology, Faculty of Physical Education and Sport Sciences, University of Tehran, Tehran, Iran


Correct kinematics is an effective factor to reduce musculoskeletal problems. The aim of this study was to compare muscle activity during single-leg squat (SLS) in a group with dynamic knee malalignment (DKMG) and normal cases. 23 active females (mean age of 21.86±2) participated in this comparative study. Lower limb Muscle activity (RMS), pelvic drop angle (PDA), trunk side bend (TSB) and knee valgus (KV) was recorded during SLS. Independent t test was used to compare variables and significance level was 0.05. The results showed no significant differences in PD (P=0.86) and TSB (P=0.25), but KV was greater in DKMG than the control group (P=0.00). Although %MVC of all muscles was greater in DKMG than the control group, only rectus femoris (P=0.04) and gluteus maximus (P=0.05) showed significant differences. Also, a weak correlation between KV with TSB (r=0.33) and rectus femoris activity (r= -0.37) was observed. Findings showed that DKMG had more muscle activity especially in rectus femoris and gluteus maximus which showed the important role of these muscles in controlling lower limb alignment during functional movements. Also, dynamic knee malalignment may deviate trunk towards weight bearing leg for substitution during SLS.


1.Benedetti, M., F. Catani, T. Bilotta, M. Marcacci, E. Mariani and S. Giannini (2003). "Muscle activation pattern and gait biomechanics after total knee replacement." Clinical biomechanics 18(9): 871-876.
2. Bryant, A. L., R. U. Newton and J. Steele (2009). "Successful feed-forward strategies following ACL injury and reconstruction." Journal of Electromyography and Kinesiology 19(5): 988-997.
3. Carcia, C. R., S. J. Shultz, K. P. Granata, D. H. Perrin and R. L. Martin (2005). "Females recruit quadriceps faster than males at multiple knee flexion angles following a weight-bearing rotary perturbation." Clinical Journal of Sport Medicine 15(3): 167-171.
4. Cesar, G. M., V. S. Pereira, P. R. P. Santiago, B. G. Benze, P. H. L. da Costa, C. F. Amorim and F. V. Serrão (2011). "Variations in dynamic knee valgus and gluteus medius onset timing in non-athletic females related to hormonal changes during the menstrual cycle." The Knee 18(4): 224-230.
5. Chappell, J. D., R. A. Creighton, C. Giuliani, B. Yu and W. E. Garrett (2007). "Kinematics and electromyography of landing preparation in vertical stop-jump risks for noncontact anterior cruciate ligament injury." The American journal of sports medicine 35(2): 235-241.
6. Clark, M. and S. Lucett (2010). NASM essentials of corrective exercise training, Lippincott Williams & Wilkins
7. Cowan, S. M., K. L. Bennell, P. W. Hodges, K. M. Crossley and J. McConnell (2001). "Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome." Archives of physical medicine and rehabilitation 82(2): 183-189.
8. Cronström, A., M. W. Creaby, J. Nae and E. Ageberg (2016). "Modifiable Factors Associated with Knee Abduction During Weight-Bearing Activities: A Systematic Review and Meta-Analysis." Sports Medicine: 1-16.
9. Crowell, H. P. and I. S. Davis (2011). "Gait retraining to reduce lower extremity loading in runners." Clinical biomechanics 26(1): 78-83.
10. Dionisio, V. C., G. L. Almeida, M. Duarte and R. P. Hirata (2008). "Kinematic, kinetic and EMG patterns during downward squatting." Journal of Electromyography and Kinesiology 18(1): 134-143.
11. Distefano, L. J., J. T. Blackburn, S. W. Marshall and D. A. Padua (2009). "Gluteal muscle activation during common therapeutic exercises." journal of orthopaedic & sports physical therapy 39(7): 532-540.
12. Heinert, B. L., T. W. Kernozek, J. F. Greany and D. C. Fater (2008). "Hip abductor weakness and lower extremity kinematics during running." Journal of sport rehabilitation 17(3): 243.
13. Hertling, D. and R. M. Kessler (2006). Management of common musculoskeletal disorders: physical therapy principles and methods, Lippincott Williams & Wilkins.
14. Hewett, T., B. Zazulak, G. Myer and K. Ford (2005). "A review of electromyographic activation levels, timing differences, and increased anterior cruciate ligament injury incidence in female athletes." British journal of sports medicine 39(6): 347-350.
15. Hewett, T. E., K. R. Ford, B. J. Hoogenboom and G. D. Myer (2010). "Understanding and preventing acl injuries: current biomechanical and epidemiologic considerations-update 2010." North American journal of sports physical therapy: NAJSPT 5(4): 234.
16. Hewett, T. E., G. D. Myer, K. R. Ford, R. S. Heidt, A. J. Colosimo, S. G. McLean, A. J. Van den Bogert, M. V. Paterno and P. Succop (2005). "Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes a prospective study." The American journal of sports medicine 33(4): 492-501.
17. Hollman, J. H., B. E. Ginos, J. Kozuchowski, A. S. Vaughn, D. A. Krause and J. W. Youdas (2009). "Relationships between knee valgus, hip-muscle strength, and hip-muscle recruitment during a single-limb step-down." Journal of sport rehabilitation 18(1): 104.
18. Homan, K. J., M. F. Norcross, B. M. Goerger, W. E. Prentice and J. T. Blackburn (2013). "The influence of hip strength on gluteal activity and lower extremity kinematics." Journal of Electromyography and Kinesiology 23(2): 411-415.
19. Ireland, M. L., J. D. Willson, B. T. Ballantyne and I. M. Davis (2003). "Hip strength in females with and without patellofemoral pain." Journal of orthopaedic & sports physical therapy 33(11): 671-676.
20. Levinger, P., W. Gilleard and C. Coleman (2007). "Femoral medial deviation angle during a one-leg squat test in individuals with patellofemoral pain syndrome." Physical Therapy in sport 8(4): 163-168.
21. Macrum, E., D. Robert Bell, M. Boling, M. Lewek and D. Padua (2012). "Effect of limiting ankle-dorsiflexion range of motion on lower extremity kinematics and muscle-activation patterns during a squat." Journal of sport rehabilitation 21(2): 144.
22. Malinzak, R. A., S. M. Colby, D. T. Kirkendall, B. Yu and W. E. Garrett (2001). "A comparison of knee joint motion patterns between men and women in selected athletic tasks." Clinical Biomechanics 16(5): 438-445.
23. Markolf, K. L., D. M. Burchfield, M. M. Shapiro, M. F. Shepard, G. A. Finerman and J. L. Slauterbeck (1995). "Combined knee loading states that generate high anterior cruciate ligament forces." Journal of Orthopaedic Research 13(6): 930-935.
24. McLean, S. G., S. W. Lipfert and A. J. van den Bogert (2004). "Effect of gender and defensive opponent on the biomechanics of sidestep cutting." Medicine and Science in Sports and Exercise 36(6): 1008-1016.
25. Medina, J. M., T. C. V. McLeod, S. K. Howell and J. J. Kingma (2008). "Timing of neuromuscular activation of the quadriceps and hamstrings prior to landing in high school male athletes, female athletes, and female non-athletes." Journal of Electromyography and kinesiology 18(4): 591-597.
26. Millet, G. Y. and R. Lepers (2004). "Alterations of neuromuscular function after prolonged running, cycling and skiing exercises." Sports Medicine 34(2): 105-116.
27. Miura, K., Y. Ishibashi, E. Tsuda, Y. Okamura, H. Otsuka and S. Toh (2004). "The effect of local and general fatigue on knee proprioception." Arthroscopy: The Journal of Arthroscopic & Related Surgery 20(4): 414-418.
28. Nagano, Y., H. Ida, M. Akai and T. Fukubayashi (2007). "Gender differences in knee kinematics and muscle activity during single limb drop landing." The Knee 14(3): 218-223.
29. Nakagawa, T. H., É. T. Moriya, C. D. Maciel and F. V. SerrãO (2012). "Trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during a single-leg squat in males and females with and without patellofemoral pain syndrome." journal of orthopaedic & sports physical therapy 42(6): 491-501.
30. Nguyen, A.-D., S. J. Shultz, R. J. Schmitz, R. M. Luecht and D. H. Perrin (2011). "A preliminary multifactorial approach describing the relationships among lower extremity alignment, hip muscle activation, and lower extremity joint excursion." Journal of athletic training 46(3): 246.
31. Olson, T. J., C. Chebny, J. D. Willson, T. W. Kernozek and J. S. Straker (2011). "Comparison of 2D and 3D kinematic changes during a single leg step down following neuromuscular training." Physical Therapy in Sport 12(2): 93-99.
32. Patrek, M. F., T. W. Kernozek, J. D. Willson, G. A. Wright and S. T. Doberstein (2011). "Hip-abductor fatigue and single-leg landing mechanics in women athletes." Journal of athletic training 46(1): 31-42.
33. Rodacki, A. L., N. E. Fowler and S. J. Bennett (2001). "Multi-segment coordination: fatigue effects." Medicine and science in sports and exercise 33(7): 1157-1167.
34. Russell, K. A., R. M. Palmieri, S. M. Zinder and C. D. Ingersoll (2006). "Sex differences in valgus knee angle during a single-leg drop jump." Journal of Athletic Training 41(2): 166.
35. Sell, T. C., C. M. Ferris, J. P. Abt, Y.-S. Tsai, J. B. Myers, F. H. Fu and S. M. Lephart (2006). "The effect of direction and reaction on the neuromuscular and biomechanical characteristics of the knee during tasks that simulate the noncontact anterior cruciate ligament injury mechanism." The American journal of sports medicine 34(1): 43-54.
36. Shultz, S. J., D. H. Perrin, J. M. Adams, B. L. Arnold, B. M. Gansneder and K. P. Granata (2000). "Assessment of neuromuscular response characteristics at the knee following a functional perturbation." Journal of Electromyography and Kinesiology 10(3): 159-170.
37. Urabe, Y., R. Kobayashi, S. Sumida, K. Tanaka, N. Yoshida, G. A. Nishiwaki, E. Tsutsumi and M. Ochi (2005). "Electromyographic analysis of the knee during jump landing in male and female athletes." The Knee 12(2): 129-134.
38. Vesci, B., D. Padua, D. Bell, L. Strickland, K. Guskiewicz and C. Hirth (2007). "Influence of hip muscle strength, flexibility of hip and ankle musculature, and hip muscle activation on dynamic knee valgus motion during a double-legged squat." J Athl Train 42(2 Suppl): 83.
39. Willson, J. D. and I. S. Davis (2008). "Utility of the frontal plane projection angle in females with patellofemoral pain." Journal of Orthopaedic & Sports Physical Therapy 38(10): 606-615.
40. Zazulak, B. T., P. L. Ponce, S. J. Straub, M. J. Medvecky, L. Avedisian and T. E. Hewett (2005). "Gender comparison of hip muscle activity during single-leg landing." Journal of Orthopaedic & Sports Physical Therapy 35(5): 292-299.
41. Zeller, B. L., J. L. McCrory, W. B. Kibler and T. L. Uhl (2003). "Differences in Kinematics and Electromyographic Activity Between Men and Women during the Single-Legged Squat*." The American journal of sports medicine 31(3): 449-456.