Effect of bicycle racing saddle design on transcutaneous penile oxygen pressure.

AIM: To determine the reliability of monitoring penile transcutaneous oxygen (tpO2) during cycling, and to assess the influence of seat design and cycling position on tpO2. EXPERIMENTAL DESIGN: repeated measures analysis of the effects of seat design and riding position on tpO2 values. PARTICIPANTS: 31 male cyclists between the ages of 20 and 50 years participated. Subject inclusion criteria were: averaged=or>80 miles of road bicycling per week during the 2 months prior to enrollment in this study; no history of vascular disease, diabetes, or sexual dysfunction; and had an erection within 15 days prior to study. MEASURES: mean tpO2 values were calculated for seated and standing positions using 3 current bicycle seat designs. RESULTS: Test-retest reliability for seated cycling tpO2 values had an ICC (3,1) of 0.76 and mean absolute difference of 5.1 mmHg. Test-retest reliability for standing cycling tpO2 values had an ICC(3,1) of 0.88 and mean absolute difference of 7.23 mmHg. No interaction effect occurred between seat design and position. Seat design had no significant effect on tpO2 values. Seated cycling significantly reduced tpO2 levels compared with standing cycling (P<0.05). Mean percent decreases in tpO2 from standing to seated cycling were; Vetta 76%, Terry 73%, and Specialized 62%. CONCLUSION: The data suggest that penile tpO2 monitoring is reliable for use during cycling studies. None of the seats exhibited any significant ability to spare penile tpO2. The implications of decreased penile tpO2 over different time intervals on penile physiology remain to be investigated.

Comparison of ball-and-racquet impact force between two tennis backhand stroke techniqes.

STUDY DESIGN: A mixed design for kinetic comparison of 2 types of one-handed backhand strokes and 2 skill levels in tennis. OBJECTIVES: To develop and evaluate a model to estimate the impact force on the racquet during tennis stroke, and to compare the peak impact force between one-handed backhand stroke with a long backswing and one-handed backhand stroke with a short backswing and between the beginning and advanced players. BACKGROUND: A one-handed backhand stroke is commonly used in tennis and may be associated with many upper extremity over-use injuries. An understanding of kinetics of the backhand stroke is essential for understanding injury mechanisms and prevention. METHODS AND MEASURES: Five male advanced tennis players and 4 male and 1 female beginning tennis players participated. Mean age was 32.2 +/- 7.0 years. Each subject was instructed to use the 2 types of one-handed backhand strokes to hit balls from a tennis ball machine. Three-dimensional coordinates of critical body and racquet landmarks were obtained. A mathematical model was developed to estimate the contact duration and the peak impact force during a stroke. RESULTS: The estimated peak impact forces were reproducible and comparable to those reported in the literature from direct measurements. A one-handed backhand stroke with a short backswing had a significantly shorter contact duration (0.008 +/- 0.003 seconds) and a greater peak resultant impact force (330.0 +/- 140.7) than that with a long backswing (0.016 +/- 0.004 seconds and 180.8 +/- 49.1 N). Skill level did not significantly affect the peak resultant impact force. CONCLUSION: A long backswing in a one-handed backhand stroke may reduce the load on the upper extremity and may assist in reducing the risks of tennis-related upper extremity over-use injuries.

Effect of foot orthotics on calcaneal eversion during standing and treadmill walking for subjects with abnormal pronation.

STUDY DESIGN: Repeated measures analysis of intervention. OBJECTIVES: To determine the effects of foot orthotics and shoewear on calcaneal eversion for standing and treadmill walking. BACKGROUND: Foot orthotics are commonly used as an intervention for treating lower extremity musculoskeletal pathology. Qualitative research regarding the benefit of foot orthotics tends to be favorable, while the results of quantitative studies often conflict. METHODS AND MEASURES: Eight men (mean age = 35.8 +/- 12.7 years) and 5 women (mean age = 30.4 +/- 10.6 years), who demonstrated abnormal pronation, walked quickly (average velocity = 1.9 m/s) on a treadmill with and without foot orthotics. Subjects were filmed using a 2-dimensional video system and plastic molds designed to indicate calcaneal position inside the shoe during static standing and treadmill walking. RESULTS: Paired t tests indicated that foot orthotics significantly reduced the mean maximum calcaneal eversion angle by 2.2 degrees and the mean calcaneal eversion angle at heel rise by 2.1 degrees during fast walking. Orthotic and nonorthotic conditions did not differ significantly for the remaining kinematic variables. A one-way ANOVA indicated that calcaneal eversion in standing was significantly greater for barefoot standing compared with standing in shoes with or without orthotics. ANOVA also indicated that the plastic molds provided reliable measures of calcaneal position. CONCLUSIONS: Foot orthotics have a significant effect on calcaneal eversion and shoes also should be considered in conjunction with foot orthotic prescription.

Relationship between lifting capacity and anthropometric measures.

STUDY DESIGN: Prospective analysis of relationship between lifting capacity and multiple anthropometric variables. OBJECTIVES: To determine the relationship between lifting capacity and anthropometric variables and to model this relationship quantitatively. BACKGROUND: Low-back injuries commonly occur in individuals who perform lifting tasks. Objective data are needed to determine preinjury lifting capacity that, in turn, might be used to guide decisions during rehabilitation of these injuries. METHODS AND MEASURES: We recorded age and sex and measured the following variables for 35 men and 23 women between the ages of 22 and 40: height, weight, percentage of body fat, torso height, pelvic width, pelvic girth, arm length, thigh girth, and calf girth. Variables were selected for the study on the basis of theoretical modeling or previous research regarding the relationship between study variables and lifting capacity. Subjects also were tested to determine their maximum lifting capacity by using a lordotic lumbar spine lifting technique. RESULTS: Stepwise regression analysis indicated that the combination of sex, age, thigh girth, pelvic girth, and percentage body fat was significantly related to maximum lift capacity (multiple R2 = 0.76). The mean absolute difference (+/- SD) between lifted amount predicted by the regression model and the actual amount lifted was 118.6 +/- 86 N (26 +/- 19.3 lb), which corresponded to an average absolute error of 16% (SD = 14%) of the actual weight lifted. CONCLUSION: The results may be useful in estimating 1 aspect of preinjury lifting capacity. Similar studies are needed to model the requirements of frequency of lift, duration of lifting efforts, variety of hand-object coupling, and combined lifting and reaching.

Effect of foot position on electromyographic activity of the vastus medialis oblique and vastus lateralis during lower-extremity weight-bearing activities.

STUDY DESIGN: Repeated measures analysis of the effects of foot wedges on quadriceps muscle function. OBJECTIVES: To investigate the relationship between foot position and 2 quadriceps muscle activation conditions: maximum voluntary isometric quadriceps muscle contractions with the knee extended and 1-leg short squats with a knee flexion range of motion of 0 degree to 50 degrees. BACKGROUND: Abnormal foot position has been suggested as an important factor which may lead to patellofemoral malalignment. No previous studies have examined the effects of foot position on activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles using weight-bearing exercises. METHODS AND MEASURES: Sixteen healthy volunteers performed the 2 exercises under 3 foot conditions: level surface, a 10 degrees medial wedge, and a 10 degrees lateral wedge. Subjects' electromyographic data for the VMO and VL were analyzed using ANOVA. RESULTS: The normalized VMO/VL ratio was significantly greater during the short squat than during the maximum voluntary isometric muscle contractions, but no significant differences were identified across the 3 foot positions. CONCLUSIONS: Clinicians should understand that the benefit of using a foot orthotic to correct a pronated or supinated foot might not result from a change in quadriceps muscle activation intensity but from other mechanical factors.

Simultaneous palpation of the craniosacral rate at the head and feet: intrarater and interrater reliability and rate comparisons.

BACKGROUND AND PURPOSE: The main purpose of this study was to determine the interrater and intrarater reliability of measurements obtained during palpation of the craniosacral rate at the head and feet. Palpated craniosacral rates of head and feet measured simultaneously were also compared. Subjects. Twenty-eight adult subjects and 2 craniosacral examiners participated in the study. METHODS: A within-subjects repeated-measures design was used. A standard cubicle privacy curtain, hung over the subject's waist, was used to prevent the examiners from seeing each other. RESULTS: Interrater intraclass correlation coefficients (ICCs) were .08 at the head and .19 at the feet. Intrarater ICCs ranged from .18 to .30. Craniosacral rates simultaneously palpated at the head and feet were different. CONCLUSION AND DISCUSSION: The results did not support the theories that underlie craniosacral therapy or claims that craniosacral motion can be palpated reliably.

An electromyographical analysis of the scapular stabilizing synergists during a push-up progression.

Current literature recommends incorporating push-up progressions into upper extremity rehabilitation for advanced training of the scapular stabilizers. No documentation exists to demonstrate changes in the level of muscle activation when push-up progressions are performed. The purpose of this study was to determine the effect of difficulty level for push-ups on electrical activity of the scapular stabilizing synergists. Sixteen subjects performed five repetitions for each of the three conditions in a push-up progression. Electromyographic data collected on the serratus anterior, upper trapezius, and lower trapezius revealed a statistically significant interaction effect between the serratus anterior and upper trapezius and push-up condition when the feet were elevated. No significant interaction was found between push-up condition and the lower trapezius. This study supports the clinical use of push-up progressions to facilitate activation of the serratus anterior and the upper trapezius during upper extremity rehabilitation.

Relationship between hip external rotation and turnout angle for the five classical ballet positions.

Functional turnout for each of the five classical ballet positions involves lower extremity motion that occurs primarily through hip external rotation. Ballet dancers often attempt to increase turnout angle through excessive motions at the foot or knee that may be associated with the development of musculoskeletal pathology. The purpose of this study was to further the understanding of turnout by identifying the relationship between available hip external rotation an functional turnout for the five classical ballet positions. Subjects were 20 female ballet dancers between the ages of 11 and 14. The investigators measured hip external rotation as the sum of passive external rotation available at both hips of each subject. Functional turnout angle was measured for each subject as the subject stood in each of the five classical ballet positions. A repeated measures analysis of variance and Tukey Honestly Significant Difference test indicated that hip external rotation was significantly less than functional turnout for the five classical ballet positions. No significant differences in functional turnout angle were present among the five ballet functional turnout angle for each of the five ballet positions. Hip external rotation should not be used to predict functional turnout for the five classical ballet positions. Turnout in first position may be useful as guide for functional turnout for the crossed foot positions: third, fourth, and fifth.

Reliability and validity of rigid lift and pelvic leveling device method in assessing functional leg length inequality.

Clinicians commonly include an assessment of leg length inequality (LLI) as a component of a musculoskeletal examination. Little research is available, however, documenting reliability and validity of clinical methods for assessing LLI. The purpose of this study was to determine the reliability and validity of assessing functional LLI using a pelvic leveling device. Subjects were 19 women and 13 men between the ages of 18 and 55 who reported having a diagnosed or suspected LLI. Clinical determination of LLI was made by placing rigid lifts under the suspected shorter lower extremity until the leveling device indicated that the iliac crests were level. This measurement was made twice by one investigator and once by a second investigator. Standing radiographic measurements of LLI using rigid lifts were used to establish validity of the clinical method. Intraclass correlation coefficients [ICC(2,1)] and absolute difference values were computed to assess reliability and validity. The mean absolute difference between the two clinical measurements of LLI by the same investigator was 0.29 cm (+/- 0.52), with an ICC = 0.84. The mean absolute difference between clinical measurements of LLI by the two investigators was 0.49 cm (+/- 0.46), with an ICC = 0.77. The ICC and mean absolute difference reflecting agreement between radiographic measurements and clinical measurements of LLI was 0.64 and 0.58 cm (+/- 0.58), respectively, for one investigator and 0.76 and 0.55 cm (+/- 0.37), respectively, for the second investigator. The intratester reliability, intertester reliability, and validity assessments included instances in which paired observations disagreed regarding which lower extremity was the shorter lower extremity. Factors that may be associated with the unacceptable reliability and validity of the clinical assessment method include asymmetric positioning of the ilia, body composition of the patient, and design of the clinical instrument. The authors discuss clinical implications related to assessment of LLI.

Effect of ankle orthoses on functional performance for individuals with recurrent lateral ankle sprains.

Ankle orthoses are commonly used for protection against initial ankle sprain injuries and for protection against reinjury. The purpose of this study was to compare the effects of the DonJoy Ankle Ligament Protector (ALP) and the Aircast Sport-Stirrup (AS) on the functional performance tasks of a 40-meter sprint, a figure-of-eight run, and standing vertical jump. Subjects were 14 males and nine females who reported a history of two or more lateral ankle sprains of the same ankle and no sprains of the contralateral ankle. Each subject performed all functional tasks on the first test day with both ankles unbraced and with the recurrently sprained ankle braced with one of the two orthoses. Each subject returned for testing on a second day and performed all tasks with both ankles unbraced and with the other orthosis on the recurrently sprained ankle. Subjects also rated the orthoses for comfort and support. Analysis of variance indicated that braced data were not significantly different than unbraced data and that data for the two orthoses did not differ significantly for any of the functional performance tasks. Seventy-four percent of the subjects reported the AS was more comfortable than the ALP, and 61% of the subjects indicated that the AS provided more support than the ALP. Neither orthosis had an effect on functional performance. The results may assist clinicians in selecting either of these orthoses for use in protection against ankle sprain injury.

Intraexaminer reliability, interexaminer reliability, and mean values for nine lower extremity skeletal measures in healthy naval midshipmen.

Physical therapists, athletic trainers, and other health care professionals commonly evaluate static postures and dynamic motions in patients with skeletal malalignments of the lower extremity. Accurate clinical evaluation of these malalignments depends on reliable and valid measures as well as established normal values. The purpose of this study was to document the intraexaminer and interexaminer reliability and mean values for nine static lower extremity skeletal measures in healthy Naval midshipmen. The measures studied were femoral torsion, ankle dorsiflexion, tibial length, leg length discrepancy, genu varus/valgus, medial talonavicular joint bulge, rearfoot angle, arch angle, and foot type classification. Intraexaminer and interexaminer reliability ICCs ranged between .65 and .97, and percentage agreements ranged between 88.8 and 94.4%. Mean absolute difference values all were within acceptable limits for clinical measurement. A foot type classification scheme was suggested. The results of this study indicate that the measures investigated are reliable when conducted on healthy Naval midshipmen by experienced examiners. Suggestions for further research are offered.

A comparison of trunk extensor strength and squat lifting ability.

Back testing devices are frequently utilized in the clinic to assess function and return to work readiness in place of the job task, yet little research on their validity has been reported. This study was conducted to determine if correlations exist between squat lifting and isoinertial and isometric trunk extensor strength, torso length and isoinertial and isometric trunk extensor strength, and body weight and isoinertial and isometric trunk extensor strength. Twenty-eight subjects participated in two sessions involving B200 testing and 30.5 cm to knuckle lifting ability. Regression and correlations were performed. The results indicate that body weight and torso length do not demonstrate a relationship with trunk extensor strength, and isometric and isoinertial trunk extensor strength cannot be used accurately to estimate one's 30.5 cm to knuckle lifting ability. In conclusion, other anthropometric measures should be investigated if anthropometrics are used to estimate strength, and functional testing should be used to evaluate function.

Lower quarter screening for skeletal malalignment--suggestions for orthotics and shoewear.

Skeletal malalignments of the lower quarter, deformities within a bone or at a joint, may be the primary cause of musculoskeletal patient problems. Skeletal malalignments also may sustain the presence of a musculoskeletal patient problem that has some other causal mechanism. A screening exam for skeletal alignment of the lower quarter may assist clinicians in identifying skeletal malalignments that are associated with a musculoskeletal complaint. The purposes of this paper are to: 1) describe components for a skeletal alignment screening exam, 2) analyze how lower quarter malalignments may influence lower quarter function and contribute to the development of musculoskeletal pathology, and 3) suggest general characteristics of foot orthoses and shoes that may assist in the management of musculoskeletal patient problems of the lower quarter.

Effect of including a clinical example on the ability of physical therapists to apply information in a technical research report.

BACKGROUND AND PURPOSE: The purpose of this study was to determine whether an example in a technical research report would affect application of content to hypothetical patient problems and to future patients. SUBJECTS: Subjects were 69 physical therapists who routinely used isokinetic equipment in the treatment of patients with knee joint pathologies. METHODS: Thirty-five subjects (group 1) read a research report that described mathematical models for predicting preinjury quadriceps femoris and hamstring muscle performance. The report included an example of applying the information. The remaining 34 subjects (group 2) read the same research report with the example omitted. Subjects were asked to select appropriate prediction models and determine preinjury knee torques for two hypothetical patients. Subjects were also contacted 6 to 12 weeks after initial data collection to determine whether they had applied research report results in their treatments of patients. RESULTS: Chi-square analyses indicated manuscript type was not related to the selection of correct models, but group 1 subjects computed correct torque values more frequently than did group 2 subjects. Insufficient data were available regarding application of research report content to patients. CONCLUSION AND DISCUSSION: The results indicate application of technically oriented research reports may be enhanced by including examples of applications. (Gross MT, Sekerak DK, Allen DD. Effect of including a clinical example on the ability of physical therapists to apply information in a technical research report.

Effect of Donjoy Ankle Ligament Protector and Aircast Sport-Stirrup orthoses on functional performance.

Clinicians often are faced with the task of selecting an ankle orthosis that will provide protection against ankle sprain injury and will not have a deleterious effect on functional performance. The purpose of this study was to compare the effects of the DonJoy Ankle Ligament Protector (ALP) and the Aircast Sport-Stirrup (AS) on three functional performance tasks: the 40-m sprint run, the figure-of-eight run, and the standing vertical jump. Subjects were eight males and eight females who reported no history of ankle injury during the 6 months prior to testing; neurological condition; lower extremity surgery or pathology; or cardiac, pulmonary, vascular, or balance problems. Each subject performed all functional tasks on the first test day with both ankles unbraced and with one randomly selected ankle braced with one of the two orthoses. Each subject returned for testing on a second day and performed all tasks with both ankles unbranced and with the other orthosis on the previously selected ankle. Subjects also rated the orthoses for comfort and support. An ANOVA indicated that braced data were not significantly different than unbraced data and that data for the two orthoses did not differ significantly for any of the functional performance tasks. Seventy-five percent of the subjects reported the AS was more comfortable than the ALP, and 63% of the subjects indicated that the ALP provided more support than the AS. Neither orthosis had a deleterious effect on functional performance. The results may assist clinicians in selecting either of these orthoses for use in protection against ankle sprain injury.

Comparison of DonJoy ankle ligament protector and subtalar sling ankle taping in restricting foot and ankle motion before and after exercise.

Clinicians often must select an appropriate prophylactic ankle support system for their patients from a variety of ankle orthoses and ankle taping configurations. The purpose of this study was to compare the effectiveness of the DonJoy Ankle Ligament Protector and a newly developed ankle taping procedure in restricting foot and ankle motion before and after exercise. Subjects were eight males and eight females who reported no history of ankle injury during the 6 months prior to testing, neurological condition, lower extremity arthritis, lower extremity fracture, or cardiac or balance problems. A Biodex dynamometer and computer were used to impose passive moments and to measure eversion and inversion prior to application of the ankle support systems, following application, and following 10 minutes of figure-of-eight running and 20 unilateral toe raises. Both ankles of each subject were assessed for each ankle support system. Subjects also compared the support systems for comfort, stability, and cosmetic acceptability. Both ankle support systems significantly reduced eversion and inversion following application and following exercise compared with preapplication measurements. Eversion measurements increased significantly following exercise for both ankle support systems compared with postapplication measurements. Inversion displacement following application was greater for the Ankle Ligament Protector than the ankle taping system. The two ankle support systems did not differ significantly following exercise for eversion or inversion measurements. The results may assist clinicians in selecting either of these ankle support systems for use in protection against ankle sprain injury.

Effect of knee angle and ligament insufficiency on anterior tibial translation during quadriceps muscle contraction: a preliminary report.

Additional information is needed regarding the effects of exercise protocols on the injured or reconstructed anterior cruciate ligament (ACL). The purpose of this investigation was to assess the effects of knee flexion angle and ACL insufficiency on anterior tibial translation (ATT) and patellar ligament insertion angle as subjects performed maximal isometric quadriceps muscle contractions. The subjects were two females and two males between the ages of 18 and 24 who had sustained injuries that resulted in unilateral ACL insufficiency. Each subject performed maximum isometric quadriceps muscle contractions with each leg on a Cybex II dynamometer at each of three positions: 15, 45, and 75 degrees knee flexion. A lateral knee roentgenogram was obtained as each subject maintained each isometric muscle contraction. A roentgenogram also was taken as subjects rested each knee in each of the three target positions. Anterior tibial translation for each isometric muscle contraction was assessed by measuring the anterior displacement of the tibial plateau on the isometric resisted roentgenogram relative to the resting roentgenogram. Patellar ligament insertion angle also was measured for each roentgenogram. Maximum ATT occurred at the 15 degrees knee flexion target angle for two subjects and at the 45 degrees target angle for the other two subjects. Patellar ligament insertion angle decreased as knee flexion angle increased. Appreciable stress may be imposed on the ACL as patients perform maximum quadriceps muscle contractions in positions of terminal knee extension and in midrange positions previously reported as being safe for maximal effort quadriceps exercise. Magnitude of stress imposed on the ACL is discussed as a function of the length-tension relationship of the quadriceps muscle-tendon unit and insertion angle of the patellar ligament. Suggestions are made for additional research regarding appropriate muscle strengthening protocols for patients who have undergone ACL reconstruction.

Chronic tendinitis: pathomechanics of injury, factors affecting the healing response, and treatment.

This paper is adapted from: Gross MT: Tendinitis. In: Prentice W, Hooker DN (eds), Postgraduate Advances in Sports Physical Therapy, I-III, pp 1-14. Berryville, VA: Forum Medicum, Inc., 1990. Figures and segments of text in this paper are reprinted with permission of Forum Medicum, Inc. Chronic tendinitis is a common and debilitating musculoskeletal pathology that can be particularly recalcitrant to treatment. Details of the composition and structure of tendon are presented, enabling clinicians to understand the mechanical function of tendon under different loading conditions and the various mechanisms of tendinitis injury. The effects of exercise, disuse, the incidence of injury, and tendinitis terminology are discussed. Other purposes of this paper are to describe the natural course of tendon healing, the clinical assessment of tendinitis, and suggested treatments for chronic tendinitis. The paper concludes with two case studies. Information in this paper should assist the clinician in treating chronic tendinitis more successfully. J Orthop Sports Phys Ther 1992;16(6):248-261.

Relationship between Multiple Predictor Variables and Normal Biodex Eversion-Inversion Peak Torque and Angular Work.

Normative data should help in the development of treatment goals. The purpose of this study was to generate predictive models relating isokinetic ankle testing performance to anthropometric and demographic variables. The subjects were 44 healthy females (age = 40.48, s = 11.98) and 43 healthy males (age = 39.83, s = 10.31) between the ages of 19 and 62. For each subject the investigators measured concentric peak torque and angular work at 60 and 120 degrees /sec for Biodex eversion and inversion. Stepwise regression analyses were used to examine the relationship between each isokinetic variable and the following predictor variables: age, side of lower extremity dominance, height, weight, percentage of body fat, leg girth, and shoe size. Separate analyses were conducted for females and males. The results indicate a significant relationship (p < 0.001) between multiple variable models and the isokinetic performance variables. The magnitude of the relationships may be explained, in part, by the restricted range of Biodex eversion and inversion measurements of peak torque and angular work. The models generated in this study can be used to establish muscle performance goals for patient rehabilitation programs. J Orthop Sports Phys Ther 1992;15(1):24-31.

Comparison of vastus medialis obliquus: vastus lateralis muscle integrated electromyographic ratios between healthy subjects and patients with patellofemoral pain.

The purpose of this study was to compare vastus medialis obliquus:vastus lateralis muscle (VMO:VL) integrated electromyographic (IEMG) ratios of healthy subjects and patients with unilateral patellofemoral pain (PFP) under isotonic and isometric quadriceps femoris muscle contraction conditions. Subjects ranging in age from 18 to 35 years (mean = 28.06, SD = 5.97) were assigned to one of three groups on the basis of type of knee condition. In group 1, which consisted of seven healthy control subjects with no history of knee pathology, both knees were tested. In group 2, which consisted of nine patients with unilateral PFP, only the painful knee was tested. In group 3, which consisted of the same nine patients who comprised group 2, only the nonpainful knee was tested. Nonnormalized and normalized VMO:VL IEMG ratios were computed for ascending stairs, descending stairs, submaximal isometric contraction, and maximal isometric contraction (nonnormalized only). A two-way analysis of variance for repeated measures indicated VMO:VL ratios for isotonic stair-climbing activities were significantly greater than VMO:VL ratios for isometric contractions. Nonnormalized VMO:VL ratios in group 1 were significantly greater than nonnormalized VMO:VL ratios in the other two groups. Patients with PFP may have abnormal VMO:VL activation patterns, and isotonic quadriceps femoris muscle exercise may elicit more favorable muscle activation patterns than isometric exercise for patients with PFP.