Hip and knee muscle function following aerobic exercise in individuals with patellofemoral pain syndrome
Introduction
Patellofemoral pain syndrome (PFPS) is one of the most commonly experienced knee disorders seen in sports medicine (Biedert and Sanchis-Alfonso, 2002, Fulkerson, 2002). PFPS is described as anterior or retropatellar pain in the absence of other specific pathologies (Crossley et al., 2001) and is more prevalent in younger populations, with females being more affected than males (Fulkerson, 1983, Boling et al., 2009). Individuals with PFPS commonly experience recurrent episodes (Biedert and Sanchis-Alfonso, 2002) which may be exacerbated with functional activities such as stair descent and ascent, squatting, kneeling, and prolonged sitting (Powers et al., 2003, Bolgla et al., 2008).
One of the possible neuromuscular factors that predispose an individual to PFPS is weakness of the gluteus medius. Patients with PFPS exhibit reduced gluteus medius strength after prolonged exercise (Dierks et al., 2008). Since the primary actions of gluteus medius are hip abduction and external rotation, weakness and fatigue of this muscle may result in greater adduction and femoral internal rotation (Powers, 2003, Dierks et al., 2008). A more valgus positioned knee from the excessive hip adduction places an increased lateral force on the patella due to greater hip adduction and knee valgus (Merchant, 1988, Dierks et al., 2008). This may result in compensatory strategies during exercise to help avoid excessive patellofemoral compressive forces (Willson and Davis, 2008).
Another potential contributing factor to PFPS is abnormal patellar tracking due to an imbalance between vastus medialis obliquus (VMO) and vastus lateralis (VL) activation. The VMO must activate prior to the VL in a 1:1 ratio (Souza and Gross, 1991) in order to balance the VL’s predominantly laterally directed force (Grabiner et al., 1994). Patients with an abnormal VMO:VL ratio are more likely to develop PFPS (Van Tiggelen et al., 2009). A decrease in the ratio, as seen in PFPS patients, is believed to represent a decrease in medial pull of the patella increasing the lateral force (Davlin et al., 1999). Fatigue in PFPS patients has been shown to have an affect on the VMO:VL ratio compared to the healthy population (Callaghan et al., 2001).
In addition to an imbalance between the VMO and VL, it has also been reported that individuals with PFPS have weaker knee extensors when compared to healthy controls (Callaghan and Oldham, 2004). Currently there is little evidence on the effects of aerobic exercise on quadriceps force and activation of the VMO, VL, and gluteus medius in individuals who are suffering from PFPS. Therefore, the purpose of this study was to compare activation of the VMO, VL, gluteus medius and knee extension torque following an aerobic exercise protocol between individuals with PFPS and healthy controls. We hypothesized that individuals with PFPS would experience decreases in knee extension torque and decreases in VMO and VL activation during a dynamic task following aerobic exercise.
Section snippets
Patients
Twenty healthy patients (age = 22.60 ± 3.62 years, height = 168.21 ± 6.63 cm, mass = 65.50 ± 7.23 kg) and twenty patellofemoral pain syndrome patients (age = 20.90 ± 1.77 years, height = 170.69 ± 6.72 cm, mass = 70.34 ± 7.88 kg, BMI = 23.9 ± 1.8) were recruited to participate in this study (see Table 1 for demographics). All patients were between the ages of 18–45 years and had a body mass index under 40. An inclusion and exclusion questionnaire, general lower extremity health history questionnaire and Kujala questionnaire (
Knee extension torque
We observed a significant group × time interaction for knee extension torque (F1,37 = 5.0, p = 0.03). Post hoc analysis indicated that baseline knee extension torque was significantly lower in PFPS patients after exercise (t1,37 = 2.6, p = 0.01) but not at baseline (p = 0.20). In our exploratory subgroup analysis, we observed a significant difference between subgroups (F2,36 = 3.7, p = 0.03) in knee extension torque after exercise. No significant differences were observed between the groups at baseline (F1,37 =
Discussion
In the current study, we had patients with and without PFPS perform an aerobic exercise and hypothesized it would cause a decrease in knee extension torque and quadriceps activation and an increase in gluteus medius activation in PFPS patients when compared to healthy controls. When PFPS patients were categorized according to change in pain, different muscle responses were observed for the gluteus medius, VMO and VL, during the single leg anterior reaching task. In patients who reported greater
Conclusion
Recreationally active individuals with PFPS may experience different responses in the quadriceps and gluteus medius after exercise. This response may be confounded by whether or not pain is exacerbated by the exercise. Clinicians should consider the gluteus medius muscle as a potential source of altered neuromuscular function of the quadriceps muscles during exercise in patients with PFPS.
Brittany Ott MEd, LAT, ATC received a BS in Athletic Training as well as a BS in Secondary Education with a concentration in Biology from the University of Nevada-Las Vegas (2008) and a MEd in Athletic Training from the University of Virginia (2010). She is currently working at Mars Hill College as an Assistant Athletic Trainer primarily with women’s soccer and baseball. She also works as the Recruitment and Retention Coordinator for their Athletic Training Education Program.
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2022, Journal of Electromyography and KinesiologyCitation Excerpt :The presence of unilateral/bilateral symptoms were clearly described in 39% of studies (n = 14) (Biabanimoghadam et al. 2016; Rojhani Shirazi et al. 2014; Bolgla et al. 2011; Brindle et al. 2003; Esculier et al. 2015; Goto et al. 2018; Mirzaie et al. 2019; Motealleh et al. 2014; Nakagawa et al. 2012a; Nakagawa et al. 2012b; Saad et al. 2011; Willson et al. 2011; Briani et al. 2019; Pompeo et al. 2021). Finally, 53% of studies (n = 19) (Biabanimoghadam et al. 2016; Rojhani Shirazi et al. 2014; Bley et al. 2014; Kalytczak et al. 2016; Boling et al. 2006; Esculier et al. 2015; Liebensteiner et al. 2008; Nakagawa et al. 2011; O'Sullivan et al. 2012; Ott et al. 2011; Song et al. 2015; Briani et al. 2019; Nunes et al. 2018; Payne et al. 2019; Baellow et al. 2020; Rodrigues et al. 2021; Glaviano and Saliba 2019; Lopes Ferreira et al. 2020; Pompeo et al. 2021) presented the participant’s physical function, with 79% (n = 15) (Bley et al. 2014; Kalytczak et al. 2016; Liebensteiner et al. 2008; Nakagawa et al. 2011; O'Sullivan et al. 2012; Ott et al. 2011; Song et al. 2015; Briani et al. 2019; Nunes et al. 2018; Payne et al. 2019; Nakagawa et al. 2012b; Baellow et al. 2020; Rodrigues et al. 2021; Glaviano and Saliba 2019; Pompeo et al. 2021; Lopes Ferreira et al. 2020) using the anterior knee pain scale. The values in the PFP group ranged between 49.6 and 85 (100 = no sign of anterior knee pain) (Tables 2-3).
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Brittany Ott MEd, LAT, ATC received a BS in Athletic Training as well as a BS in Secondary Education with a concentration in Biology from the University of Nevada-Las Vegas (2008) and a MEd in Athletic Training from the University of Virginia (2010). She is currently working at Mars Hill College as an Assistant Athletic Trainer primarily with women’s soccer and baseball. She also works as the Recruitment and Retention Coordinator for their Athletic Training Education Program.
Nicole L. Cosby, MA, ATC is a doctoral candidate at the University of Virginia, Curry School of Education, in the Sports Medicine and Athletic Training Program. Her research focus is in the area of mechanical and neurophysiological changes that occur following manual therapy in patients after ankle sprain.
Terry L. Grindstaff is an Assistant Professor in the Department of Physical Therapy at Creighton University. He earned a Bachelors of Arts in Sports Medicine from Dakota Wesleyan University, a Master of Science in Health and Physical Education from Middle Tennessee State University, a Doctorate of Physical Therapy from Belmont University, and a PhD in Kinesiology from the University of Virginia. His research examines the effects of therapeutic interventions, specifically manual therapy and exercise, on muscle activation, functional movement (gait and balance), and patient self-reported function.
Joseph M. Hart, PhD, ATC is an assistant professor of orthopaedic research at the University of Virginia, Department of Orthopaedic Surgery. He also has an academic appointment in the Curry School of Education where he teaches and mentors graduate students in the Sports Medicine and Athletic Training Program. Research focus is in the area of neuromuscular consequences of joint injury, in particular neuromuscular factors that contribute to the progression of osteoarthritis following ACL reconstruction and factors that contribute to the low back pain recurrence.