Engagement in Sedentary and Physically Active After-School Programs Among African American Children with ADHD and Disruptive Behavior Disorders.

CONTEXT: Sport and physical activity (PA) programs are an important developmental resource for youth with Attention Deficit Hyperactivity Disorder (ADHD) and Disruptive Behavior Disorders. The purpose of this study is to assess sport participation rates, PA participation, and after-school supervision rates among African American children with ADHD and/or Disruptive Behavior Disorders. DESIGN: In this cross-sectional study, parents of African American children with elevated symptoms of ADHD, oppositional defiant disorder, and/or conduct disorder (N = 175, 6- to 12-y-old, 31% female) reported after-school program participation over the past year. METHODS: Logistic regression analyses tested relationships between ADHD symptoms, oppositional defiant disorder symptoms, and conduct disorder symptoms, likelihood of regular participation (≥2 d/wk) in sport, PA, and sedentary after-school programs, and likelihood of being supervised and unsupervised after school. All regressions controlled for age, sex, income, and medication status. Sample participation rates were descriptively compared with participation rates of same-aged peers regionally, and nationally, reported in 3 national surveys. RESULTS: Parents in the local sample reported higher rates of sedentary after-school program participation (54%) but lower rates of PA program participation (31%), and sport participation (12%) compared with same-aged peers. The local sample was less likely to be unsupervised after-school compared with same-aged peers with only 27% of parents reporting that their child was unsupervised ≥ 2 days per week. Children endorsing oppositional defiant disorder (odds ratio = 2.05; P < .05) and conduct disorder (odds ratio = 5.74; P < .05) were more likely to be unsupervised more frequently after-school as compared with those not meeting endorsement. CONCLUSIONS: Given demonstrated benefits of youth sport programming and observed inequities in participation, there is a need to develop support models that connect parents, coaches, and social services agencies to facilitate inclusion. Sports medicine professionals are uniquely positioned to contribute to these efforts, as they are often key opinion leaders in both the youth sport and health care contexts.

Preventing Suicide and Promoting Mental Health Among Student-Athletes From Diverse Backgrounds.

Suicide and contributing mental health conditions in athletes are shared concerns within health care and society at large. This commentary focuses on suicide risk among athletes and the role of sports medicine professionals in preventing suicide and promoting mental health. In this commentary, we draw on the scientific literature and our clinical experiences to pose and answer these questions: Does suicide risk among athletes vary by sociodemographic factors (eg, sex, gender, race/ethnicity, family income, sexual orientation) or if injured? Do sociodemographic differences influence access to and benefits from services among athletes? How do I know my athletes are at risk for suicide? What do I do if one of my athletes shares with me that they have considered suicide? Within our commentary, we review the current literature and clinical practices regarding these questions and close with actionable suggestions and recommendations for future directions.

Post-Exercise Rehydration in Athletes: Effects of Sodium and Carbohydrate in Commercial Hydration Beverages.

The effects of varying sodium (Na) and carbohydrate (CHO) in oral rehydration solutions (ORS) and sports drinks (SD) for rehydration following exercise are unclear. We compared an ORS and SD for the percent of fluid retained (%FR) following exercise-induced dehydration and hypothesized a more complete rehydration for the ORS (45 mmol Na/L and 2.5% CHO) and that the %FR for the ORS and SD (18 mmol Na/L and 6% CHO) would exceed the water placebo (W). A placebo-controlled, randomized, double-blind clinical trial was conducted. To induce 2.6% body mass loss (BML, p > 0.05 between treatments), 26 athletes performed three 90 min interval training sessions without drinking fluids. Post-exercise, participants replaced 100% of BML and were observed for 3.5 h for the %FR. Mean ± SD for the %FR at 3.5 h was 58.1 ± 12.6% (W), 73.9 ± 10.9% (SD), and 76.9 ± 8.0% (ORS). The %FR for the ORS and SD were similar and greater than the W (p < 0.05 ANOVA and Tukey HSD). Two-way ANOVA revealed a significant interaction with the ORS having greater suppression of urine production in the first 60 min vs. W (SD did not differ from W). By 3.5 h, the ORS and SD promoted greater rehydration than did W, but the pattern of rehydration early in recovery favored the ORS.

The Relationship Between Eating Disorders, Disordered Eating, and Injury in Athletes: A Critically Appraised Topic.

CLINICAL SCENARIO: Eating disorders (EDs) and disordered eating (DE) result in numerous physical and psychological complications for female and male athletes. Besides bone-related injury, little research exists investigating what injuries EDs and/or DE contribute to. CLINICAL QUESTION: Are EDs and/or DE a risk factor for injury incidence in athletes? SUMMARY OF KEY FINDINGS: We searched for prospective studies assessing EDs or DE as a risk factor for injury in female or male athletes high school age and older. Our search returned 5 studies. One study found Eds, or DE were not a risk for any type of injury in female cross-country and track-and-field athletes. Two studies found a possible relationship between EDs or DE, as one contributing factor of others, in the incidence of bone stress injuries (BSIs) in female athletes who compete in various sports. One study found female, but not male, cross-country and track-and-field athletes with a history of EDs were more at risk for stress fractures than those without a history. One study found Eds, or DE were not a risk for BSI in female runners and triathletes. CLINICAL BOTTOM LINE: Large and important gaps in the literature exist investigating injuries related to EDs or DE outside of BSIs. There is low-moderate evidence that EDs and/or DE are either a sole, or contributing, risk factor for BSIs in female athletes. STRENGTH OF RECOMMENDATION: Grade B evidence exists to support the idea that EDs and/or DE are a risk factor for a specific type of injury (BSI) in female athletes only.

Training Load Capacity, Cumulative Risk, and Bone Stress Injuries: A Narrative Review of a Holistic Approach.

Bone stress injuries (BSIs) are a common orthopedic injury with short-term, and potentially long-term, effects. Training load capacity, influenced by risk factors, plays a critical role in the occurrence of BSIs. Many factors determine how one's body responds to repetitive loads that have the potential to increase the risk of a BSI. As a scientific community, we have identified numerous isolated BSI risk factors. However, we have not adequately analyzed the integrative, holistic, and cumulative nature of the risk factors, which is essential to determine an individual's specific capacity. In this narrative review, we advocate for a personalized approach to monitor training load so that individuals can optimize their health and performance. We define "cumulative risk profile" as a subjective clinical determination of the number of risk factors with thoughtful consideration of their interaction and propose that athletes have their own cumulative risk profile that influences their capacity to withstand specific training loads. In our narrative review, we outline BSI risk factors, discuss the relationship between BSIs and training load, highlight the importance of individualizing training load, and emphasize the use of a holistic assessment as a training load guide.

Risk Factors for Plantar Fasciitis in Physically Active Individuals: A Systematic Review and Meta-analysis.

CONTEXT: Plantar fasciitis (PF) is a common condition in active individuals. The lack of agreement on PF etiology makes treatment challenging and highlights the importance of understanding risk factors for preventive efforts. OBJECTIVE: The purpose of this systematic review and meta-analysis was to determine what factors may put physically active individuals at risk of developing PF. DATA SOURCES: CENTRAL, CINAHL, EMBASE, Gray Lit, LILACS, MEDLINE (PubMed), ProQuest, Scopus, SPORTDiscus, and Web of Science were searched through April 2018 and updated in April 2020. STUDY SELECTION: Studies were included if they were original research investigating PF risk factors, compared physically active individuals with and without PF, were written in English, and were accessible as full-length, peer-reviewed articles. STUDY DESIGN: Systematic review and meta-analysis. LEVEL OF EVIDENCE: Level 3, because of inconsistent definitions and blinding used in the included observational studies. DATA EXTRACTION: Data on sample characteristics, study design and duration, groups, PF diagnosis, and risk factors were extracted. The methodological quality of the studies was assessed using the Strengthening the Reporting of Observational Studies in Epidemiology statement. When means and standard deviations of a particular risk factor were presented 2 or more times, that risk factor was included in the meta-analysis. RESULTS: Sixteen studies were included in the systematic review and 11 risk factors in the meta-analysis. Increased plantarflexion range of motion (weighted mean difference [MD] = 7.04°; 95% CI, 5.88-8.19; P < 0.001), body mass index (MD = 2.13 kg/m2; 95% CI, 1.40-2.86; P < 0.001; I2 = 0.00%), and body mass (MD = 4.52 kg; 95% CI, 0.55-8.49; P = 0.026) were risk factors for PF. CONCLUSION: Interventions focused on addressing a greater degree of plantarflexion range of motion, body mass index, and body mass and their load on the force-absorbing plantar surface structures may be a good starting point in the prevention and treatment of active individuals with PF.

Effects of iliotibial band syndrome on pain sensitivity and gait kinematics in female runners: A preliminary study.

BACKGROUND: Runners with iliotibial band syndrome display symptoms similar to chronic tendinopathy and distinct gait patterns compared to healthy controls. Although altered pain processing has been demonstrated in chronic tendinopathies, central pain processing and its relationship to motor control has not been measured in iliotibial band syndrome. The purpose of this study was to examine pain sensitivity, hip strength, and gait kinematics in runners with and without iliotibial band syndrome. METHODS: Nine female runners with iliotibial band syndrome and eight healthy controls participated. Subjective pain was reported and pressure pain threshold measured at the bilateral foot, tibialis anterior, contralateral hand. Isometric hip strength was assessed. Three-dimensional joint angles were collected while running. Differences in pain and strength were determined using 1-way ANOVAs. Discrete hip and knee joint angles during stance phase were calculated and waveform analysis performed. FINDINGS: Runners with iliotibial band syndrome exhibited bilaterally diminished pain at the foot (injured-limb: 1.54 (SD = 0.51); non-injured limb: 1.54 (SD = 0.55); control: 4.01 (SD = 2.30) kg, P < .001) and ipsilateral tibialis anterior (injured-limb: 2.33 (SD = 1.10); control: 6.13 (SD = 4.89) kg, P = .03). Hip strength was not different between groups. Runners with iliotibial band syndrome had greater hip adduction at touchdown, knee internal rotation during loading, and knee abduction and flexion at toe-off than controls. INTERPRETATION: Runners with iliotibial band syndrome demonstrated expanded somatic pain sensitivity without hip strength differences, but concomitant with altered gait patterns. Bilateral pain symptoms and gait deviations exist in runners with iliotibial band syndrome even with unilateral symptoms, highlighting the importance of bilateral assessment.

Treatment Success of Hip and Core or Knee Strengthening for Patellofemoral Pain: Development of Clinical Prediction Rules.

CONTEXT: Patellofemoral pain (PFP) is a common injury that interferes with quality of life and physical activity. Clinical subgroups of patients may exist, one of which is caused by proximal muscle dysfunction. OBJECTIVES: To develop clinical prediction rules that predict a positive outcome after either a hip and core- or knee-focused strengthening program for individuals with PFP. DESIGN: Secondary analysis of data from a randomized control trial. SETTING: Four university laboratories. PATIENTS OR OTHER PARTICIPANTS: A total of 199 participants with PFP. INTERVENTION(S): Participants were randomly allocated to either a hip and core-focused (n = 111) or knee-focused (n = 88) rehabilitation group for a 6-week program. MAIN OUTCOME MEASURE(S): Demographics, self-reported knee pain (visual analog scale) and function (Anterior Knee Pain Scale), hip strength, abdominal muscle endurance, and hip range of motion were evaluated at baseline. Treatment success was defined as a decrease in visual analog scale score by ≥2 cm or an increase in the Anterior Knee Pain Scale score by ≥8 points or both. Bivariate relationships between the outcome (treatment success) and the predictor variables were explored, followed by a forward stepwise logistic regression to predict a successful outcome. RESULTS: Patients with more pain, better function, greater lateral core endurance, and less anterior core endurance were more likely to have a successful outcome after hip and core strengthening (88% sensitivity and 54% specificity). Patients with lower weight, weaker hip internal rotation, stronger hip extension, and greater trunk-extension endurance were more likely to have success after knee strengthening (82% sensitivity and 58% specificity). CONCLUSION: The patients with PFP who have more baseline pain and yet maintain a high level of function may experience additional benefit from hip and core strengthening. The clinical prediction rules from this study remain in the developmental phase and should be applied with caution until externally validated.

Lasting Improvement of Patient-Reported Outcomes 6 Months After Patellofemoral Pain Rehabilitation.

BACKGROUND/OBJECTIVE: Hip- and knee-muscle-strengthening programs are effective in improving short-term patient-reported and disease-oriented outcomes in individuals with patellofemoral pain (PFP), but few to no data exist on moderate- to long-term postrehabilitative outcomes. The first purpose of the study was to assess differences in pain, function, strength, and core endurance in individuals with PFP before, after, and 6 mo after successful hip- or knee-muscle-strengthening rehabilitation. The second purpose was to prospectively follow these subjects for PFP recurrence at 6, 12, and 24 mo postrehabilitation. METHODS: For 24 mo postrehabilitation, 157 physically active subjects with PFP who reported treatment success were followed. At 6 mo postrehabilitation, pain, function, hip and knee strength, and core endurance were measured. At 6, 12, 18, and 24 mo, PFP recurrence was measured via electronic surveys. RESULTS: Sixty-eight subjects (43%) returned to the laboratory at 6 mo. Regardless of rehabilitation program, subjects experienced significant improvements in pain and function, strength, and core endurance pre- to postrehabilitation and maintained improvements in pain and function 6 mo postrehabilitation (Visual Analog Scale/Pain-pre 5.12 ± 1.33, post 1.28 ± 1.14, 6 mo 1.68 ± 2.16 cm, P < .05; Anterior Knee Pain Scale/Function-pre 76.38 ± 8.42, post 92.77 ± 7.36, 6 mo 90.27 ± 9.46 points, P < .05). Over the 24 mo postrehabilitation, 5.10% of subjects who responded to the surveys reported PFP recurrence. CONCLUSIONS: The findings support implementing a hip-or knee-muscle-strengthening program for the treatment of PFP. Both programs improve pain, function, strength, and core endurance in the short term with moderate- and long-term benefits of improved pain and function and low PFP recurrence.

Individuals With Patellofemoral Pain Have Less Hip Flexibility Than Controls Regardless of Treatment Outcome.

OBJECTIVE: To examine differences in hip flexibility before and after a 6-week muscle strengthening program between those with patellofemoral pain (PFP) and healthy controls. DESIGN: Single-blind, multicentered, randomized controlled trial. SETTING: Four clinical research laboratories. SUBJECTS: Physically active individuals (199 PFP and 38 controls). INTERVENTIONS: Patellofemoral pain and control subjects were randomized into either a hip-focused or a knee-focused muscle strengthening treatment program. MAIN OUTCOME MEASURES: Pain-visual analog scale (centimeter), function-Anterior Knee Pain Scale (points), flexibility-passive goniometry (degrees): hip adduction (HADD), hip external rotation (HER), hip internal rotation (HIR), total hip rotation (HROT), hip extension (HEXT) were measured before and after the muscle strengthening treatment program. RESULTS: Subjects with patellofemoral pain who successfully completed the treatment program (n = 153) had 65%, 25%, 18%, and 12% less HADD, HER, HROT, and HIR ranges of motion (ROMs), respectively, than controls (P < 0.05). Patellofemoral pain subjects who did not successfully complete the program (n = 41) had 134%, 31%, 22%, and 13% less HADD, HER, HROT, and HIR ROMs, respectively, than controls (P < 0.05). All subjects increased their HIR, HROT, and HEXT ROMs pretest to posttest (P < 0.05), but by less than 2 degree. CONCLUSIONS: Individuals with PFP had less hip flexibility than controls regardless of treatment outcome or time. After the 6-week muscle strengthening program, and regardless of treatment success, PFP and control subjects experienced a small but clinically insignificant improvement in hip flexibility. CLINICAL RELEVANCE: Hip ROM should be considered as a targeted area of focus in a rehabilitation program for physically active individuals with PFP.

Risk factors for medial tibial stress syndrome in physically active individuals such as runners and military personnel: a systematic review and meta-analysis.

Medial tibial stress syndrome (MTSS) is a common injury in runners and military personnel. There is a lack of agreement on the aetiological factors contributing to MTSS, making treatment challenging and highlighting the importance of preventive efforts. Understanding the risk factors for MTSS is critical for developing preventive measures. The purpose of this systematic review and meta-analysis was to assess what factors put physically active individuals at risk to develop MTSS. Selected electronic databases were searched. Studies were included if they contained original research that investigated risk factors associated with MTSS, compared physically active individuals with MTSS and physically active individuals without MTSS, were in the English language and were full papers in peer-reviewed journals. Data on research design, study duration, participant selection, population, groups, MTSS diagnosis, investigated risk factors and risk factor definitions were extracted. The methodological quality of the studies was assessed. When the means and SDs of a particular risk factor were reported three or more times, that risk factor was included in the meta-analysis. There were 21 studies included in the systematic review and nine risk factors qualified for inclusion in the meta-analysis. Increased BMI (weighted mean difference (MD)=0.79, 95% CI 0.38 to 1.20, p<0.001), navicular drop (MD=1.19 mm, 95% CI 0.54 to 1.84, p<0.001), ankle plantarflexion range of motion (ROM; MD=5.94°, 95% CI 3.65 to 8.24, p<0.001) and hip external rotation ROM (MD=3.95°, 95% CI 1.78 to 6.13, p<0.001) were risk factors for MTSS. Dorsiflexion and quadriceps-angle were clearly not risk factors for MTSS. There is a need for high-quality, prospective studies using consistent methodology evaluating MTSS risk factors. Our findings suggest that interventions focused on addressing increased BMI, navicular drop, ankle plantarflexion ROM and hip external rotation ROM may be a good starting point for preventing and treating MTSS in physically active individuals such as runners and military personnel.

The influence of training and mental skills preparation on injury incidence and performance in marathon runners.

There has been a considerable increase in the number of participants running marathons over the past several years. The 26.2-mile race requires physical and mental stamina to successfully complete it. However, studies have not investigated how running and mental skills preparation influence injury and performance. The purpose of our study was to describe the training and mental skills preparation of a typical group of runners as they began a marathon training program, assess the influence of training and mental skills preparation on injury incidence, and examine how training and mental skills preparation influence marathon performance. Healthy adults (N = 1,957) participating in an 18-week training program for a fall 2011 marathon were recruited for the study. One hundred twenty-five runners enrolled and received 4 surveys: pretraining, 6 weeks, 12 weeks, posttraining. The pretraining survey asked training and mental skills preparation questions. The 6- and 12-week surveys asked about injury incidence. The posttraining survey asked about injury incidence and marathon performance. Tempo runs during training preparation had a significant positive relationship to injury incidence in the 6-week survey (ρ[93] = 0.26, p = 0.01). The runners who reported incorporating tempo and interval runs, running more miles per week, and running more days per week in their training preparation ran significantly faster than did those reporting less tempo and interval runs, miles per week, and days per week (p ≤ 0.05). Mental skills preparation did not influence injury incidence or marathon performance. To prevent injury, and maximize performance, while marathon training, it is important that coaches and runners ensure that a solid foundation of running fitness and experience exists, followed by gradually building volume, and then strategically incorporating runs of various speeds and distances.

Effectiveness of external-rotation immobilization after initial shoulder dislocation in reducing recurrence rates.

CLINICAL SCENARIO: Initial, traumatic shoulder dislocations, particularly in an anterior direction, are among the most common shoulder injuries. Traditionally, nonsurgical treatment for first-time shoulder dislocations consists of immobilization in internal rotation (IR). However, there is a high rate of recurrence after this course of treatment. Recent reports indicate that immobilization in external rotation (ER) instead of IR may more effectively reduce recurrence rates, resulting in a viable nonsurgical treatment option for patients sustaining an initial shoulder dislocation.

Effective exercises for targeting the gluteus medius.

CLINICAL SCENARIO: The gluteus medius (GM) is thought to play an important role in stabilizing the pelvis and controlling femoral adduction and internal rotation during functional activity. GM weakness, resulting in decreased stabilization and control, has been suggested to be related to lower extremity dysfunction and injury. Many clinicians focus on strengthening the GM to improve lower extremity kinematics for the prevention and rehabilitation of injury. An indirect way to measure GM strength is through electromyography. It is generally assumed that exercises producing higher levels of activation will result in greater strengthening effects.3 Understanding what exercises result in the greatest level of GM activation will assist clinicians in their injury prevention and rehabilitation efforts. FOCUSED CLINICAL QUESTION: In a healthy adult population, what lower extremity exercises produce the greatest mean GM activation, expressed as a percentage of maximum voluntary isometric contraction?

Descriptive epidemiology of collegiate women's softball injuries: National Collegiate Athletic Association Injury Surveillance System, 1988-1989 through 2003-2004.

OBJECTIVE: To review 16 years of National Collegiate Athletic Association (NCAA) injury surveillance data for women's softball and to identify potential areas for injury prevention initiatives. BACKGROUND: The NCAA Injury Surveillance System has tracked injuries in all divisions of NCAA softball from the 1988-1989 to the 2003-2004 seasons. This report describes what was found and why the findings are important for the safety, enhancement, and continued growth of the sport. MAIN RESULTS: Across all divisions, preseason practice injury rates were more than double the regular-season practice injury rates (3.65 versus 1.68 injuries per 1000 athlete-exposures, rate ratio = 2.2, 95% confidence interval [CI] = 2.0, 2.4, P < .01). The rate of injury in a game was 1.6 times that in a practice (4.30 versus 2.67 injuries per 1000 athlete-exposures, rate ratio = 1.6, 95% CI = 1.5, 1.7). A total of 51.2% of game injuries resulted from "other-contact" mechanisms, whereas 55% of practice injuries resulted from noncontact mechanisms. In games, ankle ligament sprains and knee internal derangements accounted for 19% of injuries. Twenty-three percent of all game injuries were due to sliding, most of which were ankle sprains. In practices, ankle ligament sprains, quadriceps and hamstring strains, shoulder strains and tendinitis, knee internal derangements, and lower back strains (combined) accounted for 38% of injuries. RECOMMENDATIONS: Ankle ligament sprains, knee internal derangements, sliding injuries, and overuse shoulder and low back injuries were among the most common conditions in NCAA women's softball. Preventive efforts should focus on sliding technique regardless of skill level, potential equipment changes, neuromuscular training programs, position-specific throwing programs, and mechanisms of low back injury. Further research is needed on the development and effects of these preventive efforts, as well as in the area of windmill-pitching biomechanics.

Gender comparisons of dynamic restraint and motor skill in children.

OBJECTIVES: To assess differences in neuromuscular dynamic restraint between high-skilled and low-skilled prepubescent girls and boys. To determine the contribution of sport experience and physical characteristics to motor skill. SUBJECTS: Nineteen girls and 17 boys (8.89-9.40 y) participated. INTERVENTION: Isometric hamstring and quadriceps muscle strength was assessed. Subjects performed 3 landing trials for measurement of preparatory EMG and vertical leg stiffness. Motor skill was assessed through analysis of 12 fundamental tasks. Sport experience was reported as hours per week and total years in organized and nonorganized activity. OUTCOME MEASURES: Dynamic restraint variables of isometric strength, preparatory EMG activity, and vertical leg stiffness were measured between groups. The contributions of time in sport, type of sport, and physical characteristics on skill were analyzed. RESULTS: No significant gender or skill differences were found in quadriceps strength (P = 0.73), hamstring strength (P = 0.96), hamstring-to-quadriceps ratio (P = 0.71), or vertical leg stiffness (P = 0.38). Low-skilled children exhibited significantly greater (47.8%) preparatory hamstring-quadriceps coactivation than high-skilled subjects (P = 0.03). Participation in organized and nonorganized sport accounted for 29% of the variance in motor skill. CONCLUSIONS: Neuromuscular differences between genders were not observed, but dynamic restraint EMG measures differed between skill levels. The factors predisposing females to noncontact injuries may develop prepuberty to postpuberty from a combination of variables. Greater coactivation in the low-skilled group appears consistent with immature feedforward neuromuscular control strategies. These unrefined motor skills are less economical, may compromise dynamic restraint, and appear partially determined by sport experience.

Joint stiffness and pain in individuals with patellofemoral syndrome.

STUDY DESIGN: Pretest-posttest matched control group design. OBJECTIVES: To measure passive knee joint stiffness and pain in participants with and without patellofemoral pain syndrome (PFPS) and to determine the relationship between mechanical knee joint stiffness, self-reported stiffness, and pain. BACKGROUND: Patients with PFPS complain of knee joint stiffness and pain, but no research has quantified both of these characteristics in this population. METHODS AND MEASURES: Twenty-eight individuals (14 with PFPS [mean age +/- SD, 25.5 +/- 4.8 years] and 14 healthy controls [mean age +/- SD, 22.8 +/- 5.4 years]) volunteered for this study. Mechanical passive knee joint stiffness was calculated using the damped natural frequency of oscillation of the lower leg while sitting. Mechanical stiffness was compared to self-reports of knee stiffness and pain. All measurements were recorded presitting and after 20 minutes of sitting. RESULTS: Sitting for 20 minutes did not induce significant changes in mechanical knee joint stiffness. However, participants with PFPS reported significantly greater (P<.01) knee stiffness after sitting for 20 minutes. A significant correlation (r = 0.70, P<.01) was found between self-reported stiffness and pain in participants with PFPS; however, no significant relationship was observed between mechanical and self-reported knee joint stiffness. CONCLUSIONS: Despite frequent complaints of joint stiffness, the knees of individuals with PFPS do not appear physiologically stiffer than those of control subjects. Individuals with PFPS perceive increased knee stiffness after sitting, but may misinterpret the sensation of pain as joint stiffness.