High prevalence of contralateral ankle abnormalities in association with knee osteoarthritis and malalignment.

OBJECTIVE: To evaluate ankle joint abnormalities in a knee osteoarthritis (OA) cohort. METHODS: Participants (n = 159) with symptomatic and radiographic OA in at least one knee underwent technetium-99m methylene diphosphonate bone scan (scored 0-3) of the ankles and forefeet. Knee radiographs were graded for OA features of joint space narrowing (JSN) and osteophyte (OST). Ankle symptoms and history of ankle injury were assessed by self-report. Knee alignment was measured from a long-limb radiograph. Ankle radiographs were obtained on those who returned for follow-up (n = 138) and were graded for ankle tibiotalar JSN and OST. DESIGN: Ankle scintigraphic abnormalities were frequent (31% of individuals, one-third bilateral). Ankle symptoms were reported by 23% of individuals and history of ankle injury by 24%. Controlling for gender, age, body mass index (BMI), and contralateral predictor, ankle scintigraphic abnormalities were associated with: ipsilateral ankle symptoms (P = 0.005); contralateral knee JSN (P = 0.001), knee OST (P = 0.006) and knee malalignment (P = 0.08); and history of ankle injury or surgery of either ankle (P < 0.0001). At follow-up, scintigraphic abnormalities of the ankle were strongly associated with presence of tibiotalar radiographic OA (P < 0.0001). CONCLUSIONS: Although considered rare, we observed a high prevalence of radiographic features of ankle OA in this knee OA cohort. History of overt ankle injury did not appear to account for the majority of ankle abnormalities. These results are consistent with a probable kinematic association of knee OA pathology and contralateral ankle abnormalities and suggest that interventions targeting mechanical factors may be needed to prevent ankle OA in the setting of knee OA.

Association of bone scintigraphic abnormalities with knee malalignment and pain.

OBJECTIVE: The information content of knee bone scintigraphy was evaluated, including pattern, localisation and intensity of retention relative to radiographic features of knee osteoarthritis, knee alignment and knee symptoms. METHODS: A total of 308 knees (159 subjects) with symptomatic and radiographic knee osteoarthritis of at least one knee was assessed by late-phase (99m)Technetium methylene disphosphonate bone scintigraph, fixed-flexion knee radiograph, full limb radiograph for knee alignment and for self-reported knee symptom severity. Generalised linear models were used to control for within-subject correlation of knee data. RESULTS: The compartmental localisation (medial vs lateral) and intensity of knee bone scan retention were associated with the pattern (varus vs valgus) (p<0.001) and severity (p<0.001) of knee malalignment and localisation and severity of radiographic osteoarthritis (p<0.001). Bone scan agent retention in the tibiofemoral, but not patellofemoral, compartment was associated with severity of knee symptoms (p<0.001) and persisted after adjusting for radiographic osteoarthritis (p<0.001). CONCLUSION: To the authors' knowledge, this is the first study describing a relationship between knee malalignment, joint symptom severity and compartment-specific abnormalities by bone scintigraphy. This work demonstrates that bone scintigraphy is a sensitive and quantitative indicator of symptomatic knee osteoarthritis. Used selectively, bone scintigraphy is a dynamic imaging modality that holds great promise as a clinical trial screening tool and outcome measure.

Influence of joint position on electromyographic and torque generation during maximal voluntary isometric contractions of the hamstrings and gluteus maximus muscles.

STUDY DESIGN: Repeated measures analysis of joint angle effects on hip and knee muscle electromyographic (EMG) activity. OBJECTIVES: To simultaneously determine angle-dependent changes in maximal voluntary isometric contraction (MVIC) torque and EMG activity during hip extension and knee flexion. BACKGROUND: Procedures for normalizing EMG data and for determining torque-angle relationships for various joint motions both entail asking subjects to exert an MVIC. The implicit assumption in these paradigms is that magnitude of the EMG response is at a constant, maximum level so that observed angle-dependent variations in torque are due to mechanical factors, such as muscle length and muscle moment arm. METHODS AND MEASURES: Fifty subjects (25 men and 25 women) participated in this study (age, 23.5 +/- 4.6 y; range, 18-38 y). Subjects performed maximal isometric knee flexion at 4 knee angles and maximal isometric hip extension at 4 hip angles. The dependent variables were normalized root-mean-square EMG and torque. The process for normalizing EMG and torque data consisted of determining the largest mean value for each subject across testing positions for the muscle of interest. That value was designated as corresponding to 100% MVIC, and all other data for that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVIC-torque and MVIC-EMG values for each muscle group. RESULTS: Mean torque-angle relationships were generally consistent with previous reports, though considerable intersubject variability was observed. There were significant angle-dependent differences in maximal EMG for both the hamstring and gluteus maximus muscles. Mean percentages of hamstring MVIC-EMG at knee angles of 30 degrees (81 +/- 19) and 60 degrees (82 +/- 22) were greater than at 0 degrees (68 +/- 20) or 90 degrees (74 +/- 20). The mean percentage of gluteus maximus MVIC-EMG at a hip angle of 0 degrees (94 +/- 10) was greater than at 30 degrees (84 +/- 13), 60 degrees (80 +/- 14), or 90 degrees (64 +/- 20), and gluteus maximus maximal voluntary isometric EMG at 90 degrees was less than at all other angles. These differences could not be explained solely by muscle length-dependent effects on EMG amplitude, suggesting that despite instructions for maximal effort, motor unit activation was not maintained at a constant, maximal level throughout the range of motion. The form of the EMG/angle relationships differed markedly from the torque-angle relationships. CONCLUSIONS: These findings have implications for the use of MVIC-EMG for reference values in EMG normalization procedures and for the interpretation of mechanisms underlying the torque-angle relationships observed in vivo.

Effects of a static stretching program on the incidence of lower extremity musculotendinous strains.

OBJECTIVE: Musculotendinous strains are among the most prevalent injuries for which health care professionals provide treatment and rehabilitation interventions. Flexibility has been identified as one of the primary etiologic factors associated with musculotendinous strains, but limited research exists on the effect of a preventive stretching program on musculotendinous strains. Therefore, the purpose of our study was to compare the number of musculotendinous strains for the hamstrings, quadriceps, hip adductors, and gastrocnemius-soleus muscle groups before and after the incorporation of a static stretching program for each muscle group. DESIGN AND SETTING: We analyzed the incidence of musculotendinous strains among the players of a Division III collegiate football team between 1994 and 1995. All variables were consistent between the 2 seasons except for the incorporation of a lower extremity stretching program in 1995. SUBJECTS: One hundred and ninety-five Division III college football players. MEASUREMENTS: We calculated the number of musculotendinous strains that required a minimum absence of 1 day from practices or games in 1994 and 1995. RESULTS: A x(2) analysis revealed a significant reduction in the number of lower extremity musculotendinous strains in 1995 as opposed to 1994. CONCLUSIONS: Our statistical analysis indicates an association between the incorporation of a static stretching program and a decreased incidence of musculotendinous strains in Division III college football players.

Thigh and calf girth following knee injury and surgery.

Girth measures are commonly used to assess muscle atrophy or joint effusion. Little is known, however, regarding girth measurement changes following knee injury and subsequent surgery. Therefore, the purpose of this study was to compare the thigh and calf girth measurements of involved and noninvolved extremities prior to and following knee surgery for subjects with acute and chronic knee injuries. Of the 40 subjects that were studied, 22 subjects were placed in the acute group (less than 6 months from time of injury to presurgery measurement) and 18 subjects were placed in the chronic group (greater than 6 months from time of injury to presurgery measurement). Thigh and calf girth measurements were taken prior to surgery and then prior to the initiation of outpatient rehabilitation following surgery. For the acute and chronic groups, a three-way analysis of variance (ANOVA) with repeated measures on the extremity, muscle, and time factors was used to analyze the data. For each group, the three-way ANOVA revealed a significant two-way interaction between the extremity and time factors. Post hoc analysis revealed significant differences between involved and noninvolved extremities at both the pre- and post-surgery time periods for the acute and chronic groups. While thigh and calf girth measurement differences existed between the involved and noninvolved extremities prior to and after surgery, the bulk of the girth measurement differences existed prior to surgery for both groups. Based upon the results of this study, the assessment and rehabilitation of the thigh and calf following knee injury and surgery are recommended.

Electromyographic reliability and analysis of selected lower extremity muscles during lateral step-up conditions.

OBJECTIVE: To determine 1) the electromyographic (EMG) reliability within and between testing sessions; 2) the effect of sex on the EMG activity of the vastus medialis oblique (VMO), vastus lateralis (VL), hamstring (HS), and gluteus maximus (GM) and VMO:VL ratios during maximal voluntary isometric contraction (MVIC) and lateral step-up (LSU) conditions; and 3) the muscle recruitment and VMO:VL ratios during MVIC and LSU conditions. DESIGN AND SETTING: Subjects participated in a familiarization session and two testing sessions in which they performed a 20.32-cm (8-in) LSU with and without resistance while the EMG activity was monitored for the VMO, VL, HS, and GM muscles. SUBJECTS: Nineteen subjects performed LSUs holding 25% body weight (Group 25%), and 13 subjects performed LSUs holding 10% body weight (Group 10%). There were 32 subjects total: 19 males and 13 females. MEASUREMENTS: Statistical analyses included a two-way analysis of variance (ANOVA) to compare sex and testing conditions for percentage of MVIC and VMO:VL ratios; three-way repeated-measures ANOVA to compare muscle, resistance, and session factors for percentage of MVIC; and a two-way repeated-measures ANOVA to compare conditions and session factors for VMO:VL ratios. These analyses were performed for both groups. RESULTS: Reliability results revealed good intrasession and poor intersession intraclass correlation coefficients. No difference existed in muscle recruitment or VMO:VL ratios between males and females for either group. The three-way ANOVA revealed a significant two-way interaction (muscle x resistance) for both groups. Post hoc testing revealed the following EMG recruitment patterns: VMO > HS, GM, VL;VL > HS, GM; HS = GM for both groups. For Group 25%, the two-way ANOVA revealed greater VMO:VL ratios during MVIC for session one than for LSU. CONCLUSIONS: Intrasession reliability was higher than intersession reliability, but similar conclusions were reached concerning muscle recruitment in both testing situations. No sex differences existed in recruitment patterns. The LSU requires greater VMO and VL recruitment than HS and GM recruitment. In addition, VMO:VL ratios varied tremendously in a group of asymptomatic subjects, which challenges the theory of a "normal" VMO:VL ratio of 1:1 in asymptomatic subjects.

An objective measurement technique for posterior scapular displacement.

Contemporary shoulder rehabilitation programs emphasize scapular control in the treatment of shoulder pathology. In addition, scapular winging and scapular tipping are often cited as key components to both the evaluative and rehabilitative phase of treatment. However, the lack of objective measurement procedures makes clinical evaluation of these phenomena difficult. The purpose of this project was to develop a reliable technique to quantify posterior scapular displacement (direction of scapular movement for winging and/or tipping). Forty healthy subjects (21 males, 19 females) who reported no current shoulder pain participated in this study. A measurement instrument was designed to quantify, to the nearest whole degree of motion, the posterior displacement of the inferior angle of the scapula from the posterior thorax. Subjects' scapulae were each measured two times without holding weight (unweighted position) and two times while the subjects held 10% of their body weight (weighted position). During all trials, two testers were blinded from the measurement readings. Intraclass correlation coefficients (ICC) were calculated based on a repeated measure analysis of variance to determine intertester and intratester reliability. The standard error of measurement (SEM) was used to determine the measurement error. Intratester within-day reliability ICCs ranged from 0.97 to 0.98, and SEM ranged from 0.6 to 1.1 degrees. Intertester within-day reliability ICCs ranged from 0.92 to 0.97, and SEM ranged between 1.1 and 1.7 degrees. None of the calculated p values for intratester and intertester reliability were statistically significant (p < 0.05). We conclude that this measurement technique is a reliable method to quantify posterior scapular displacement. Further research utilizing this measurement technique is recommended.

EMG analysis of lower extremity muscle recruitment patterns during an unloaded squat.

During an unloaded squat, hamstring and quadriceps co-contraction has been documented and explained via a co-contraction hypothesis. This hypothesis suggests that the hamstrings provide a stabilizing force at the knee by producing a posteriorly-directed force on the tibia to counteract the anterior tibial force imparted by the quadriceps. Research support for this hypothesis, however, is equivocal. Therefore, the purposes of this study were 1) to determine muscle recruitment patterns of the gluteus maximus, hamstrings, quadriceps, and gastrocnemius during an unloaded squat exercise via EMG and 2) to describe the amount of hamstring-quadriceps co-contraction during an unloaded squat. Surface electrodes were used to monitor the EMG activity of six muscles of 41 healthy subjects during an unloaded squat. Each subject performed three 4-s maximal voluntary isometric contractions (MVIC) for each of the six muscles. Electrogoniometers were applied to the knee and hip to monitor joint angles, and each subject performed three series of four complete squats in cadence with a metronome (50 beats.min-1). Each squat consisted of a 1.2-s eccentric, hold, and concentric phase. A two-way repeated measures ANOVA (6 muscles x 7 arcs) was used to compare normalized EMG (percent MVIC) values during each arc of motion (0-30 degrees, 30-60 degrees, 60-90 degrees, hold, 90-60 degrees, 60-30 degrees, 30-0 degrees) of the squat. Tukey post-hoc analyses were used to quantify and interpret the significant two-way interactions. Results revealed minimal hamstring activity (4-12% MVIC) as compared with quadriceps activity (VMO: 22-68%, VL: 21-63% of MVIC) during an unloaded squat in healthy subjects. This low level of hamstring EMG activity was interpreted to reflect the low demand placed on the hamstring muscles to counter anterior shear forces acting at the proximal tibia.

Factors associated with menstrual irregularities and decreased bone mineral density in female athletes.

Menstrual irregularities occur in some female athletes. The most extreme form of menstrual irregularity is amenorrhea, which has been linked to significant decreases in vertebral bone density and increases in injury prevalence. Many authors have sought to determine the causal factors of athletic amenorrhea, some of which include hormonal status, training and physical parameters, nutritional balance, and psychological stress. The purpose of this paper was to compare studies that have examined the relationship of these variables to menstrual irregularities and bone density. Controversy exists regarding the relative contribution of these variables. The etiology is likely multifactorial and should be evaluated as such. Clinicians treating female athletes must be knowledgeable about the negative consequences associated with menstrual irregularities. Furthermore, it is critical that clinicians provide thorough patient education in order to prevent injuries and the long-term loss of bone density. Appropriate medical and/or psychological referral of the athlete with menstrual irregularities may be necessary.

A reliability study of measurement techniques to determine static scapular position.

Current shoulder rehabilitation programs encourage scapular stabilization components although, to date, no scientific studies have evaluated changes in scapular position following such rehabilitation. Four different measurement methods of scapular position have been reported in the literature. The purpose of this study was to examine the intratester and intertester reliability of these four methods and to also examine if significant differences exist in scapular position between dominant and nondominant extremities. Thirty-two subjects volunteered for this study. Intraclass correlation coefficients (ICC) revealed acceptable intratester reliability (ICC = 0.81-0.95) for all measurement methods. However, while one method also proved to be acceptable (ICC = 0.91-.92) for intertester measurements, the other three methods were unacceptable (ICC = 0.18-0.69). One tester reported significant differences in scapular position of the dominant and nondominant extremities when using the most reliable method. The second tester found no significant differences with either method. Future research is recommended to reexamine reliability of these methods and measure subjects with shoulder pathology.

Effect of hamstring stretching on hamstring muscle performance.

The relationship between hamstring flexibility and hamstring muscle performance has not been reported. The purposes of this study were 1) to determine the most effective stretching method for increasing hamstring flexibility and 2) to determine the effects of increasing hamstring flexibility on isokinetic peak torque. Nineteen subjects participated in this study. A two-way analysis of variance was used to compare two stretching techniques: proprioceptive neuromuscular facilitation stretch and static stretch. A one-way repeated measures analysis of variance was used to compare hamstring isokinetic values pre- and poststretching. No significant increase occurred (p < .05) in hamstring flexibility even though increases occurred with each technique: static stretch (+21.3%) and proprioceptive neuromuscular facilitation (+25.7%). Significant increases occurred in peak torque eccentrically at 60 degrees/sec (p < .05, +8.5%) and 120 degrees/sec (p < .05, +13.5%) and concentrically at 120 degrees/sec (p < .05, +11.2%). No significant increase occurred at 60 degrees/sec (p > .05, +2.5%). We concluded that increasing hamstring flexibility was an effective method for increasing hamstring muscle performance at selective isokinetic conditions. Further study is needed to determine if increasing hamstring flexibility will increase performance in closed kinetic chain activities.

Hip isometric strength following knee surgery.

Hip exercises are frequently prescribed following knee injury and subsequent surgery based on the assumption that hip weakness exists. No data, however, are available that support hip weakness following knee trauma or surgery. Therefore, the purpose of this study was to compare hip strength in patients after knee surgery. Twenty-seven patients who had undergone unilateral knee surgery were tested for hip flexor, extensor, abductor, and adductor isometric strength prior to initiation of rehabilitation. Multivariate analysis of variance revealed significant hip weakness in all four hip muscle groups of the surgical extremities (11.9-25.3%, p < or = 0.05) when compared with nonsurgical extremities. Both peak and endurance force were affected. The greatest percent difference between the surgical and nonsurgical extremity occurred for hip extension peak (25.3%) and endurance (22.6%) force development. We recommend assessment of hip strength following knee surgery and appropriate resistive exercises if weakness exists.

Effect of foot position on gastrocnemius/soleus stretching in subjects with normal flexibility.

Following injury to the ankle or lower extremity, stretching of the gastrocnemius/soleus complex is commonly prescribed. Many authors recommend stretching the gastrocnemius/soleus complex with the foot placed in a supinated position. No research is available, however, that supports the efficacy of stretching in the supinated vs. the pronated position. Therefore, the purpose of this study was to compare the effect of stretching the gastrocnemius/soleus complex in two foot positions: supinated and pronated. Eleven female and eight male subjects completed 10 stretching sessions with one foot supinated and the other foot pronated. Each stretching session consisted of four 20-second stretches. On pretest and posttest measurements, maximum dorsiflexion range of motion and stretching force exerted through the foot were recorded for each subject. Foot position for the testing procedures and the stretching phase was standardized with individually constructed footprint templates. A two-way analysis of variance (stretching position and time) was used to compare pretest and posttest ankle dorsiflexion measurements. Results indicated a significant increase in dorsiflexion (p = 0.01, pronation + 6.36%, supination + 6.24%) but no significant difference between stretching positions (p = 0.23). We concluded that gastrocnemius/soleus complex stretching in either foot position is effective for increasing dorsiflexion range of motion in healthy subjects with normal flexibility of the gastrocnemius/soleus complex.

Factors associated with hamstring injuries. An approach to treatment and preventative measures.

Following hamstring strain, rehabilitation is often prolonged and frustrating for the athlete and for the sports medicine clinician. Though the initial treatment of rest, ice, compression and elevation is accepted for muscle strains, no consensus exists for rehabilitation of hamstring muscle strains. This lack of agreement concerning rehabilitation of hamstring injury represents our lack of understanding of the mechanism of injury and the factors that contribute to hamstring strain. A hamstring rehabilitation model is proposed that is based on our current understanding of the aetiological factors that contribute to hamstring muscle strain. The influence and interaction of hamstring strength, flexibility, warm-up and fatigue are aetiological factors that should be addressed in the rehabilitation and prevention of hamstring strains. The rehabilitation model is, however, not without limitations and speculations. Further research is needed to clarify the etiological factors of hamstring strain and the efficacy of different rehabilitation protocols.

Two measurement techniques for assessing subtalar joint position: a reliability study.

Proper assessment of the subtalar joint is critical for foot and ankle evaluation. Yet, reliability of open kinetic chain goniometric measurements of the subtalar joint has been poor. Two alternative techniques, navicular height and calcaneal position with an inclinometer, have been reported in the literature but lack reliability assessment. The purpose of this study was to determine the intertester and intratester reliability of navicular height and calcaneal position using an inclinometer. Thirty healthy, volunteer subjects (22 females, age 24 +/- 3.6 years; eight males, age 25 +/- 5.1 years) participated in this study. Two testers performed repeated measures on both feet of each subject (N = 60) during two testing sessions. Testers determined the 1) subtalar neutral position, 2) resting position, and 3) difference between these two measurements using an inclinometer for calcaneal position and navicular height. Intratester and intertester reliabilities (ICC 2, 1), standard errors of measurement, and 95% confidence intervals were determined. Intertester and intratester reliability for calcaneal position ranged from .68 to .91 for all measurements. Intertester and intratester reliability for navicular height ranged from .73 to .96 for all measurements. We conclude that these weight-bearing measurement techniques are reliable and acceptable for clinical and research purposes as measured. In addition, we hypothesize that these measurement techniques are simpler than previously described open kinetic chain methods.

Effect of hip position on gravity effect torque.

Hip position has been hypothesized to influence gravity effect torque (GET) at the knee during isokinetic testing; however, no data exist to support or refute this hypothesis. Therefore, the purposes of this study were 1) to determine if a significant difference exists between GET in seated and supine positions, 2) to determine the effect of the supine and seated GET on isokinetic peak torque values, and 3) to determine the relationship between hamstring flexibility and GET. Gravity effect torque was recorded in supine and seated positions. Peak torque values in flexion and extension were obtained on a isokinetic dynamometer at 1.047 and 5.235 rads.s-1 (60 and 300 degrees.s-1, respectively). Hamstring flexibility was assessed by the active knee extension test (AKET). The mean seated GET value was 5.64 Nm higher than the mean supine GET value (F(1,82) = 97.85, P = 0.0001). Significant correlations existed between hamstring flexibility and GET values measured in the seated and supine positions (r = 0.45, P = 0.0001, and r = 0.30, P = 0.0058, respectively). Significant differences in peak torque values occurred for three of the four isokinetic conditions when using different GET values (P-value 0.0002-0.0049). Although mean differences in peak torque values were only 2.43-4.23 Nm, these differences may translate to significant errors in the isokinetic measurement of the injured population undergoing rehabilitation. Furthermore, every attempt should be made to improve the validity of isokinetic testing. Therefore, we recommend the supine position for GET determination.

Effect of a lateral step-up exercise protocol on quadriceps and lower extremity performance.

Closed kinetic chain exercises have been promoted as more functional and more appropriate than open kinetic chain exercises. Limited research exists demonstrating the effect of closed kinetic chain exercise on quadriceps and lower extremity performance. The purpose of this study was to determine the effect of a lateral step-up exercise protocol on isokinetic quadriceps peak torque and the following lower extremity activities: 1) leg press, 2) maximal step-up repetitions with body weight plus 25%, 3) hop for distance, and 4) 6-m timed hop. Twenty subjects participated in a 4-week training period, and 18 subjects served as controls. For the experimental group, a repeated measure ANOVA comparing pretest and posttest values revealed significant improvements in the leg press (p < or = .05), step-ups (p < or = .05), hop for distance (p < or = .05), and hop for time (p < or = .05) and no significant increase in isokinetic quadriceps peak torque (p > or = .05). Over the course of the training period, weight used for the step-up exercise increased (p < or = .05), repetitions decreased (p < or = .05), and step-up work did not change (p > or = .05). For the control group, no significant change (p > or = .05) occurred in any variable. The inability of the isokinetic dynamometer to detect increases in quadriceps performance is important because the isokinetic values are frequently used as criteria for return to functional activities. We conclude that closed kinetic chain testing and exercise provide additional means to assess and rehabilitate the lower extremity.

The relationship between quadriceps angle and anterior knee pain syndrome.

Anterior knee pain syndrome (AKPS) represents a significant challenge for patients and for clinicians. The purposes of this study were: 1) to determine the reliability of the Q-angle measurement, 2) to quantify Q-angle changes that occur with knee flexion, and 3) to determine if subjects with AKPS (N = 52) have a significantly different Q-angle than subjects without AKPS (N = 50). With the knee in an extended position, intratester Q-angle intraclass correlation coefficients (ICC) ranged from .84 to .90, and standard error of measurement (SEM) values ranged from 2.01 to 2.23 degrees. Intertester Q-angle ICC was .83, and the SEM was 2.49 degrees. With the knee flexed, the intratester ICC was .83 for both testers, and SEM values ranged from 0.68 to 2.45 degrees. Intertester ICC and SEM were .65 and 3.50 degrees, respectively. No significant difference was found in intratester Q-angle values between the extended and flexed knee positions (p > 0.05). No significant difference in Q-angle was found between asymptomatic subjects (11.1 +/- 5.5 degrees) and symptomatic subjects (12.4 +/- 5.1 degrees) (p = 0.07). Increased Q-angles were not responsible for AKPS in this group of patients. Other factors were hypothesized to be responsible for their symptoms.

Effect of pelvic position and stretching method on hamstring muscle flexibility.

Hamstring muscle strain represents a significant injury to the athlete participating in sporting activities. Lack of hamstring flexibility has been correlated to hamstring muscle injury. There is, however, conflict concerning the most efficient hamstring stretching technique. The purpose of this study was to compare static stretch (SS) and proprioceptive neuromuscular facilitation (PNF) hamstring stretching techniques while maintaining the pelvis in two testing positions: anterior pelvic tilt (APT) or posterior pelvic tilt (PPT). Two groups of 10 subjects were randomly assigned to either an APT or PPT position. Each subject then performed eight sessions using PNF on one leg and SS on the other leg while maintaining the pelvis in the assigned position. Hamstring flexibility was assessed with the hip positioned at 90 degrees while actively extending the knee, i.e., active knee extension test (AKET). A two-way ANOVA comparing stretching technique and pelvic position revealed that the APT group significantly increased hamstring flexibility (P = 0.0375). There was not a significant difference between SS or PNF stretching technique in the APT position. There was not a significant increase in hamstring flexibility in the PPT group with either stretching technique (P > 0.05). The results suggest that APT position was more important than stretching method for increasing hamstring muscle flexibility.