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Efficacy of Feedback on Running Gait Retraining in Patients With Patellofemoral Pain: A Critically Appraised Topic

Hyunjae Jeon and Abbey C. Thomas

Clinical Question: Is it beneficial to utilize feedback motion retraining in improving gait biomechanics, pain, and self-reported function on patients with patellofemoral pain (PFP)? Clinical Bottom Line: There is sufficient evidence to support the use of feedback motion retraining to improve gait, pain, and function in PFP rehabilitation.

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Differences in Gluteal and Quadriceps Muscle Activation Among Adults With and Without Lumbar Hyperlordosis

Mohammad H. Izadi Farhadi, Foad Seidi, Hooman Minoonejad, and Abbey C. Thomas

Context: Many factors have been reported contributing to altering the neuromuscular function of hip and knee muscles. The lumbar hyperlordosis, as a poor posture in some athletes, is thought to be associated with the alteration of the hip and knee muscles activity. Objective: To examine the activation of selected hip and knee muscles in athletes with and without lumbar hyperlordosis during functional activities. Design: Case-control study. Setting: University laboratory. Participants: Twenty-six college male athletes (n = 13 with and n = 13 without lumbar hyperlordosis). Interventions: Surface electromyography of gluteus maximus (GMAX), gluteus medius (GMED), vastus medialis oblique (VMO), and vastus lateralis (VL) were recorded during single-leg squat and single-leg jump landing (SLJL) tasks. Main Outcome Measure: Preactivity; reactivity; and onset muscle during SLJL and eccentric activity during single-leg squat (GMAX, GMED, VMO, and VL along with the ratio of VMO:VL) were assessed. Results: Athletes with lumbar hyperlordosis had a higher level of activity in their GMAX (P = .003), VMO (P = .04), and VL (P = .01) muscles at the moment before foot contact during SLJL. These athletes also demonstrated a higher level of GMAX activity (P = .01) immediately after foot contact. Finally, athletes with lumbar hyperlordosis activated their GMAX sooner (P = .02) during the SLJL. Athletes with normal lumbar lordosis had more activity in their GMED muscle (P = .001) in the descending phase of the single-leg squat task and a higher VMO:VL (P = .01) at the moment after the foot contact during the SLJL. Conclusion: The altered activation of GMAX, GMED, VMO, VL, and VMO:VL can reveal the role of lumbar hyperlordosis in the knee and hip muscles’ alteration in athletes. Further study is needed to identify whether these alterations in the hip and knee muscles contribute to injury in athletes.

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Influence of Chronic Ankle Instability on Physical Activity: A Critically Appraised Topic

Priya Patel, Luke Donovan, Tricia Hubbard-Turner, and Abbey C. Thomas

Lateral ankle sprains are the most common injury sustained by physically active individuals. The overwhelming majority of people who sprain their ankle go on to develop chronic ankle instability (CAI). CAI may cause affected individuals to limit their physical activity, leading to health issues such as obesity and cardiovascular disease. The growing body of literature suggests that functional limitations reported by individuals with CAI may lead a the decrease in physical activity. This critically appraised topic sought to determine if adolescent and college-aged individuals with CAI have lower physical activity levels than their healthy peers. A literature search was conducted in between August 2021–February 2022 using the terms “chronic ankle instability” and “physical activity.” Studies were included if the participants were adolescent or college-aged and had CAI. Three studies meeting the inclusion criteria were identified. The first study reported that college students with CAI walk fewer steps per week than their healthy peers, while the second study observed higher physical activity levels among adolescents with CAI. The third study incorporated details on how there is a high prevalence of ankle injury in adolescents, so methods to prevent the injury should be followed to avoid injury earlier on. Despite the conflicting evidence on how CAI impacts physical activity levels, physical activity remains important for long-term health. Thus, it is necessary to emphasize that individuals with CAI should seek treatment to mitigate recurrent ankle sprains in order to safely continue with physical activity.

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Plyometrics Did Not Improve Jump-Landing Biomechanics in Individuals With a History of Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Trial

Hyunjae Jeon, Sean Krysak, Steven J. Pfeiffer, and Abbey C. Thomas

Second anterior cruciate ligament (ACL) injury has similar biomechanical risk factors as primary injury. Standard of care rehabilitation does not adequately mitigate these biomechanical risks. This study examined the effectiveness of a 4-week plyometric intervention on biomechanical risk factors of second ACL injury versus no intervention in patients with a history of ACL reconstruction. Thirty adults post-ACL reconstruction received 12 sessions of plyometric (age: 19.9 ± 1.62 years; body mass index: 23.9 ± 2.6 kg/m2; months postoperative: 35.7 ± 24.2) or no (age: 21.3 ± 3.5 years; body mass index: 27.7 ± 4.8 kg/m2; months postoperative: 45.3 ± 25.4) exercise intervention. Hip and knee biomechanics were quantified during a jump-landing task before and after the intervention. Individual response to the intervention was evaluated via minimal detectable change. Hip flexion angle had the greatest response to plyometric training. Overall, focused plyometric intervention did not adequately mitigate biomechanical risk factors of second ACL injury; thus, development of interventions capable of modifying biomechanics known to contribute to ACL injury risk remains necessary.

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Agreement Between Investigators Using Paired-Pulse Transcranial Magnetic Stimulation to Assess Quadriceps Intracortical Excitability

Abbey C. Thomas, Brian G. Pietrosimone, and Carter J. Bayer

Context: Transcranial magnetic stimulation (TMS) may provide important information regarding the corticospinal mechanisms that may contribute to the neuromuscular activation impairments. Paired-pulse TMS testing is a reliable method for measuring intracortical facilitation and inhibition; however, little evidence exists regarding agreement of these measures in the quadriceps. Objective: To determine the between-sessions and interrater agreement of intracortical excitability (short- and long-interval intracortical inhibition [SICI, LICI] and intracortical facilitation [ICF]) in the dominant-limb quadriceps. Design: Reliability study. Setting: Research laboratory. Participants: 13 healthy volunteers (n = 6 women; age 24.7 ± 2.1 y; height 1.7 ± 0.1 m; mass 77.1 ± 17.4 kg). Intervention: Participants completed 2 TMS sessions separated by 1 wk. Main Outcome Measures: Two investigators measured quadriceps SICI, LICI, and ICF at rest and actively (5% of maximal voluntary isometric contraction). All participants were seated in a dynamometer with the knee flexed to 90°. Intracortical-excitability paradigm and investigator order were randomized. Bland-Altman analyses were used to establish agreement. Results: Agreement was stronger between sessions within a single investigator than between investigators and for active than resting measures. Agreement was strongest for resting SICI and active ICF and LICI between sessions for each investigator. Conclusions: Quadriceps intracortical excitability may be measured longitudinally by a single investigator, though active muscle contraction should be elicited during testing.

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Quadriceps and Hamstrings Fatigue Alters Hip and Knee Mechanics

Abbey C. Thomas, Scott G. McLean, and Riann M. Palmieri-Smith

Neuromuscular fatigue exacerbates abnormal landing strategies, which may increase noncontact anterior cruciate ligament (ACL) injury risk. The synergistic actions of quadriceps and hamstrings (QH) muscles are central to an upright landing posture, though the precise effect of simultaneous fatigue of these muscles on landing and ACL injury risk is unclear. Elucidating neuromechanical responses to QH fatigue thus appears important in developing more targeted fatigue-resistance intervention strategies. The current study thus aimed to examine the effects of QH fatigue on lower extremity neuromechanics during dynamic activity. Twenty-five healthy male and female volunteers performed three single-leg forward hops onto a force platform before and after QH fatigue. Fatigue was induced through sets of alternating QH concentric contractions, on an isokinetic dynamometer, until the first five repetitions of a set were performed at least 50% below QH peak torque. Three-dimensional hip and knee kinematics and normalized (body mass × height) kinetic variables were quantified for pre- and postfatigue landings and subsequently analyzed by way of repeated- measures mixed-model ANOVAs. QH fatigue produced significant increases in initial contact (IC) hip internal rotation and knee extension and external rotation angles (p < .05), with the increases in knee extension and external rotation being maintained at the time of peak vertical ground reaction force (vGRF) (p < .05). Larger knee extension and smaller knee fexion and external rotation moments were also evident at peak vGRF following fatigue (p < .05). Females landed with greater hip fexion and less abduction than males at both IC and peak vGRF as well as greater knee fexion at peak vGRF (p < .05). The peak vGRF was larger for females than males (p < .05). No sex × fatigue effects were found (p > .05). Fatigue of the QH muscles altered hip and knee neuromechanics, which may increase the risk of ACL injury. Prevention programs should incorporate methods aimed at countering QH fatigue.

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Athletic Trainers’ Osteoarthritis Consortium: Raising Awareness of Osteoarthritis in the Sports Medicine Community

Abbey C. Thomas and Jeffrey B. Driban

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Effects of Real-Time Video Feedback on Plantar Pressure Measures in Individuals With Chronic Ankle Instability During Walking

Anna M. Ifarraguerri, Danielle M. Torp, Abbey C. Thomas, and Luke Donovan

Individuals with chronic ankle instability (CAI) have been shown to have increased lateral plantar pressure during walking which is thought to contribute to symptoms associated with CAI. The objective of this study was to determine whether real-time video feedback can reduce lateral plantar pressure in individuals with CAI. Twenty-six participants with CAI completed 30 s of treadmill walking while plantar pressure was measured using an in-shoe plantar pressure system (baseline). Next, participants completed an additional 30 s of treadmill walking while receiving video feedback (VID FB). During the VID FB condition, participants had a significant decrease in medial forefoot peak pressure and medial midfoot pressure-time integral; however, both changes were associated with small effect sizes. Real-time video feedback did not reduce lateral plantar pressure in individuals with CAI; therefore, other gait retraining strategies should be considered when treating patients with CAI.

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Evaluation of Agreement Between Participant and Expert on Jump-Landing Characteristics During a 4-Week Intervention

Hayley M. Ericksen, Brian Pietrosimone, Phillip A. Gribble, and Abbey C. Thomas

Context: Feedback is an important factor in interventions designed to reduce anterior cruciate ligament injury risk. Self-analysis feedback requires participants to self-critique their jump-landing mechanics; however, it is unknown if individuals can effectively self-analyze their own biomechanics and if this self-analysis agrees with observed biomechanical changes by an expert. Objective: To determine agreement between an expert and participants on biomechanical errors committed during 3 of 12 sessions, which were part of an intervention to change jump-landing biomechanics in healthy females. Design: Descriptive analysis. Setting: Research laboratory. Patients or Other Participants: Healthy recreationally active females with no history of lower-extremity fracture or surgery. Interventions: Participants completed a 4-week, 12-session feedback intervention. Each intervention session lasted approximately 15 minutes and included asking participants to perform 6 sets of 6 jumps off a 30-cm-high box placed 50% of their height away from the target landing area. Participants performed self-analysis feedback and received expert feedback on 7 different jump-landing criteria following each set of jumps. Main Outcome Measures: Data were coded, and agreement between the expert and the participant was assessed using Cohen’s unweighted kappa for sessions 1, 6, and 12. Results: There was agreement between the expert and participants for 0/7 criteria for session 1, 3/7 criteria for session 6, and 4/7 criteria for session 12. Conclusions: Participants demonstrated some agreement with the expert when evaluating their jump-landing biomechanics. Self-analysis feedback may not replace what an expert can provide; both types of feedback may be better used in conjunction to produce significant biomechanical changes. Changes made by the participant may not translate into biomechanical changes during a real-life game or practice situation. Future research should continue to investigate effective interventions to reduce injury risk.

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Fatigue’s Lack of Effect on Thigh-Muscle Activity in Anterior Cruciate Ligament–Reconstructed Patients During a Dynamic-Landing Task

Lindsey K. Lepley, Abbey C. Thomas, Scott G. McLean, and Riann M. Palmieri-Smith


As individuals returning to activity after anterior cruciate ligament reconstruction (ACLr) likely experience fatigue, understanding how fatigue affects knee-muscle activation patterns during sport-like maneuvers is of clinical importance. Fatigue has been suggested to impair neuromuscular control strategies. As a result, fatigue may place ACLr patients at increased risk of developing posttraumatic osteoarthritis (OA).


To determine the effects of fatigue on knee-muscle activity post-ACLr.


Case control.


University laboratory.


12 individuals 7–10 mo post-ACLr (7 male, 5 female; age 22.1 ± 4.7 y; 1.8 ± 0.1 m; mass 77.7 ± 11.9 kg) and 13 controls (4 male, 9 female; age 22.9 ± 4.3 y; 1.7 ± 0.1 m; mass 66.9 ± 9.8 kg).


Fatigue was induced via repetitive sets of double-leg squats (n = 8), which were interspersed with sets of single-leg landings (n = 3), until squats were no longer possible.

Main Outcome Measures:

2 × 2 repeated-measures ANOVA was used to detect the main effects of group (ACLr, control) and fatigue state (prefatigue, postfatigue) on quadriceps:hamstring cocontraction index (Q:H CCI).


All subjects demonstrated higher Q:H CCI at prefatigue compared with postfatigue (F 1,23 = 66.949, P ≤ .001). Q:H CCI did not differ between groups (F 1,23 = 0.599, P = .447).


The results indicate that regardless of fatigue state, ACLr individuals are capable of restoring muscle-activation patterns similar to those in healthy subjects. As a result, excessive muscle cocontraction, which has been hypothesized as a potential mechanism of posttraumatic OA, may not contribute to joint degeneration after ACLr.