Knee Extensor Power Research Articles

337 EVALUATION OF LONG-TERM TREATMENT WITH TAPENTADOL EXTENDED RELEASE AND OXYCODONE CONTROLLED RELEASE IN PATIENTS WITH CHRONIC LOW BACK OR OSTEOARTHRITIS PAIN: RESULTS FROM PATIENT AND PHYSICIAN GLOBAL ASSESSMENTS AND THE EUROQOL 5 DIMENSION QUESTIONNAIRE

speed were obtained using the Short Physical Performance Battery (SPPB) test. Pain and physical function were measured using the WOMAC. Pearson partial correlations and linear regression analyses adjusted for age, sex, and BMI were used to examine the relationships among the variables of interest. Results: A lower percent lower extremity fat (thigh + leg) was significantly associated with reduced pain (r=0.54; p=0.02), greater physical function (r=0.66; p=0.003), and higher knee extensor strength (r=-0.58, p=0.01). No significant associations were found between percent trunk fat and these measures. Greater knee extensor strength was also significantly associated with reduced pain (r=-0.42; p=0.02) and greater physical function (r=-0.46; p=0.01). In addition, higher leg extensor power was significantly associated with faster chair rise time (r=-0.76; p=0.001) and walking speed (r=0.54; p=0.03). Conclusions: These results suggest that lower extremity fat, but not trunk fat, and weak knee extensor strength and power may play important roles in the increased pain and poor function common in older adults with knee OA. Improving knee extensor strength and reducing thigh fat may provide long-term improvements in pain and function.

336 TAPENTADOL EXTENDED RELEASE FOR THE RELIEF OF CHRONIC OSTEOARTHRITIS KNEE PAIN: RESULTS FROM THE EUROQOL-5 DIMENSION (EQ-5D) AND WESTERN ONTARIO AND MACMASTER UNIVERSITIES OSTEOARTHRITIS INDEX (WOMAC) QUESTIONNAIRES

speed were obtained using the Short Physical Performance Battery (SPPB) test. Pain and physical function were measured using the WOMAC. Pearson partial correlations and linear regression analyses adjusted for age, sex, and BMI were used to examine the relationships among the variables of interest. Results: A lower percent lower extremity fat (thigh + leg) was significantly associated with reduced pain (r=0.54; p=0.02), greater physical function (r=0.66; p=0.003), and higher knee extensor strength (r=-0.58, p=0.01). No significant associations were found between percent trunk fat and these measures. Greater knee extensor strength was also significantly associated with reduced pain (r=-0.42; p=0.02) and greater physical function (r=-0.46; p=0.01). In addition, higher leg extensor power was significantly associated with faster chair rise time (r=-0.76; p=0.001) and walking speed (r=0.54; p=0.03). Conclusions: These results suggest that lower extremity fat, but not trunk fat, and weak knee extensor strength and power may play important roles in the increased pain and poor function common in older adults with knee OA. Improving knee extensor strength and reducing thigh fat may provide long-term improvements in pain and function.

Muscle Deficits Persist After Unilateral Knee Replacement and Have Implications for Rehabilitation

Knee joint arthritis causes pain, decreased range of motion, and mobility limitation. Knee replacement reduces pain effectively. However, people with knee replacement have decreases in muscle strength ("force-generating capacity") of the involved leg and difficulties with walking and other physical activities. The aim of this cross-sectional study was to determine the extent of deficits in knee extensor and flexor muscle torque and power (ability to perform work over time) and in the extensor muscle cross-sectional area (CSA) after knee joint replacement. In addition, the association of lower-leg muscle deficits with mobility limitations was investigated. Participants were 29 women and 19 men who were 55 to 75 years old and had undergone unilateral knee replacement surgery an average of 10 months earlier. The maximal torque and power of the knee extensor and flexor muscles were measured with an isokinetic dynamometer. The knee extensor muscle CSA was measured with computed tomography. The symmetry deficit between the knee that underwent replacement surgery ("operated knee") and the knee that did not undergo replacement surgery ("nonoperated knee") was calculated. Maximal walking speed and stair-ascending and stair-descending times were assessed. The mean deficits in knee extensor and flexor muscle torque and power were between 13% and 27%, and the mean deficit in the extensor muscle CSA was 14%. A larger deficit in knee extension power predicted slower stair-ascending and stair-descending times. This relationship remained unchanged when the power of the nonoperated side and the potential confounding factors were taken into account. The study sample consisted of people who were relatively healthy and mobile. Some participants had osteoarthritis in the nonoperated knee. Deficits in muscle torque and power and in the extensor muscle CSA were present 10 months after knee replacement, potentially causing limitations in negotiating stairs. To prevent mobility limitations and disability, deficits in lower-limb power should be considered during rehabilitation after knee replacement.

Aerobic exercise training improves whole muscle and single myofiber size and function in older women

To comprehensively assess the influence of aerobic training on muscle size and function, we examined seven older women (71 +/- 2 yr) before and after 12 wk of cycle ergometer training. The training program increased (P < 0.05) aerobic capacity by 30 +/- 6%. Quadriceps muscle volume, determined by magnetic resonance imaging (MRI), was 12 +/- 2% greater (P < 0.05) after training and knee extensor power increased 55 +/- 7% (P < 0.05). Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of individual slow (MHC I) and fast (MHC IIa) myofibers, myosin light chain (MLC) composition, and muscle protein concentration. Aerobic training increased (P < 0.05) MHC I fiber size 16 +/- 5%, while MHC IIa fiber size was unchanged. MHC I peak power was elevated 21 +/- 8% (P < 0.05) after training, while MHC IIa peak power was unaltered. Peak force (Po) was unchanged in both fiber types, while normalized force (Po/cross-sectional area) was 10% lower (P < 0.05) for both MHC I and MHC IIa fibers after training. The decrease in normalized force was likely related to a reduction (P < 0.05) in myofibrillar protein concentration after training. In the absence of an increase in Po, the increase in MHC I peak power was mediated through an increased (P < 0.05) maximum contraction velocity (Vo) of MHC I fibers only. The relative proportion of MLC(1s) (Pre: 0.62 +/- 0.01; Post: 0.58 +/- 0.01) was lower (P < 0.05) in MHC I myofibers after training, while no differences were present for MLC(2s) and MLC(3f) isoforms. These data indicate that aerobic exercise training improves muscle function through remodeling the contractile properties at the myofiber level, in addition to pronounced muscle hypertrophy. Progressive aerobic exercise training should be considered a viable exercise modality to combat sarcopenia in the elderly population.

Assessing The Reliability Of Asymmetrical Strength And Power Deficit Evaluation In Functionally-Limited Elders

PURPOSE: The purpose of this study was to assess the reliability of evaluating asymmetrical strength and power deficits in the lower-limbs of functionally-limited elders. METHODS: A cross-sectional evaluation was performed on 57 older (74.2 ± 0.9y, 26 male, SPPB ≤9) adults. Testing was performed twice, at the same time of day, separated by one week. Bilateral knee extensor strength and power was evaluated on Keiser pneumatic resistance training equipment. Asymmetrical strength deficit was defined as the 1 Repetition Maximum (1RM) difference between the right and left legs (Right Leg 1RM - Left Leg 1RM). Asymmetrical power deficit was defined as the difference in Peak Power (PP) between the right and left legs (Right Leg PP - Left Leg PP) at resistances equal to 40% and 70% of the 1RM. The results from the two individual testing days were evaluated for test-retest reliability. In addition, the relationship between asymmetrical strength and power and various measures of functional performance was explored. RESULTS: Asymmetrical strength (Intra Class Correlation (ICC) = 0.799) and power @ 40 (ICC = 0.698) and 70% (ICC = 0.708) of 1RM all showed fair reliability between the two testing days. Correlations showed a moderate association between asymmetrical strength and power and chairstand time: strength (r = 0.497, p < 0.003) and power @ 40 (r = 0.315, p < 0.042) and 70% (r = 0.330, p < 0.021) of 1RM. CONCLUSIONS: These findings support the reliability of evaluating asymmetrical strength and power deficits in the lower limbs of functionally-limited elders as well as the existence of a relationship between strength and power asymmetry and functional performance. Supported by USDA 58-1950-4-401 and NIA RO1-AG-18844

Decreased knee extensor torque and power production in human heart failure

Exercise intolerance is a hallmark symptom of chronic heart failure. The goal of this study was to determine if heart failure impairs skeletal muscle torque, power production or contractile velocity. Heart failure patients (n=11; 70.4 ± 4.3 yrs) and controls (n=11; 70.3 ± 3.4 yrs) matched for age, sex and medications that may affect muscle function were evaluated for knee extensor contractile performance, body composition and physical activity level. Groups did not differ in total or regional body composition or physical activity level. Despite similarities in muscle size and use, heart failure patients were characterized by 21‐29% lower (P&lt;0.05 to P&lt;0.01) isometric knee extensor torque throughout a range of knee angles, 15‐33% lower (P=0.05 to P&lt;0.01) peak torque and power output at various isokinetic speeds. These differences in muscle function were evident after adjustment of data for muscle mass. Expression of peak isokinetic torque data relative to isometric torque eliminated group differences, suggesting that impaired function under dynamic conditions is explained by deficits in the force generating capacity of muscle. No group differences were found in the time required to reach target velocity during isokinetic contractions, a proxy of contractile velocity. These results suggest that heart failure reduces skeletal muscle peak torque and power production, but does not alter contractile velocity.

Knee Extensor Mechanism Reconstruction with an Extended Gastrocnemius Flap and a Saphenous Neurocutaneous Flap

A 35-year-old woman had multiple fractures due to pedestrian versus motor vehicle accident by a truck. An open comminuted patellar fracture was initially managed with a tension band and cerclage wiring and primary closure of the wound. Other fractures were managed with proper internal fixation. Unfortunately, the fractured patella and overlying soft tissue became totally infected and a wide necrosis occurred. To control the wound, a complete debridement of dead tissue was undertaken and the patella and its tendon were removed, leaving a large bone and soft tissue defect on the knee joint. To reconstruct the extensor mechanism, an extended medial gastrocnemius flap including a tendinous portion of the Achilles was used. A saphenous neurocutaneous flap was simultaneously used for additional soft tissue coverage around the proximal tibia and remaining patellar tendon. At 12 months postoperatively, she showed complete extension, 135 degrees of flexion, and grade IV knee extensor power and was able to ambulate without a walking aid.

Reduced knee extensor function in heart failure is not explained by inactivity

Background The goal of this study was to determine if heart failure alters knee extensor muscle torque, power production or contractile velocity. Methods Heart failure patients ( n = 11; 70.4 ± 4.3 yrs) and controls ( n = 11; 70.3 ± 3.4 yrs) matched for age and sex were evaluated for knee extensor contractile performance under isometric and isokinetic conditions and body composition by dual energy X-ray absorptiometry. Additionally, we recruited sedentary to minimally active elderly controls to match heart failure patients for habitual physical activity and assessed activity levels using accelerometry. Results Groups did not differ for total or regional body composition or average daily physical activity level. Despite similar muscle size and use, heart failure patients exhibited 21–29% lower ( P < 0.05 to P < 0.01) isometric knee extensor torque throughout a range of knee angles, 15–33% lower ( P = 0.05 to P < 0.01) peak concentric torque measured at various isokinetic speeds and corresponding reductions ( P = 0.05 to P < 0.01) in peak power output. Expression of peak isokinetic torque data relative to isometric torque eliminated group differences, suggesting that impaired contractile function under dynamic conditions is explained by deficits in the force generating capacity of muscle. No group differences were found in the time required to reach target velocity during isokinetic contractions, an index of contractile velocity. Conclusion Because group differences in muscle torque were independent of age, sex, physical activity level and muscle size, our results suggest that muscle contractile dysfunction in these patients is likely attributable to the heart failure syndrome.

Assessment of lower extremity muscle power in functionally-limited elders

The purpose of this study was to assess the reliability and concurrent validity of a new methodology to evaluate lower extremity muscle power in older, functionally limited men and women. A cross sectional evaluation was performed on 58 older men (n=27) and women (n=31) (74.2+/-0.9 years). Knee and hip (leg press) and knee extensor power were evaluated on pneumatic and isokinetic resistance equipment. Incremental single attempt power (IP) testing utilized a single attempt at attaining maximum power at each of six external resistances and was compared to multiple attempt pneumatic power (MP) testing determined by the highest of 5 attempts at achieving maximum power at two set resistances and also with power determined by isokinetic dynamometry. Leg press extension MP yielded significantly greater power than IP at both low (mean=225.3+/-11.85 and 183.9+/-11.52 watts respectively, p<0.001) and high (mean=249.7+/-15.25 and 201.7+/-13.18 watts respectively, p<0.001) external resistances. Knee extension MP also produced significantly greater power when compared to IP at low (mean=82.4+/-4.45 and 69.7+/-4.28 watts respectively, p<0.001) and high (mean=93.7+/-6.3 and 83.2+/-5.93 watts respectively, p<0.001) external resistances. MP testing exhibited excellent reliability at both low (leg press extension: Intra Class Correlation (ICC)=0.93, knee extension: ICC=0.87) and high (Leg press extension: ICC=0.85, Knee Extension: ICC=0.91) external resistances. MP knee extension at 70% 1 RM also showed good agreement with average isokinetic power (R2=0.636). These findings support the reliability and concurrent validity of MP for the evaluation of muscle power in older individuals.

Selective dorsal rhizotomy for children with cerebral palsy: the Oswestry experience

Background:Although three randomised control trials have shown that selective dorsal rhizotomy (SDR) reduces spasticity in children with cerebral palsy, a meta-analysis of the results demonstrated that the procedure conferred only...

Muscle-Power Quality: Does Sex or Race Affect Movement Velocity in Older Adults?

To determine sex and race differences in muscle power per unit of muscle contraction, knee-extensor muscle power normalized for knee-extensor muscle volume was measured in 79 middle-aged and older adults (30 men and 49 women, age range 50-85 years). Results revealed that women displayed a 38% faster peak movement velocity than men and African Americans had a 14% lower peak movement velocity than Whites of a similar age when expressed per unit of involved muscle (p < .001). As expected, men exhibited greater knee-extensor strength and peak power per unit of muscle than women, but women had a faster knee- extension movement velocity per unit of muscle than men at the same relative strength level. Moreover, African Americans had greater knee-extensor muscle volume than Whites but exhibited lower knee-extensor strength and lower movement velocity per unit of muscle when tested at the same relative strength levels.

Moderate Velocity Strength Training Increases Peak Muscle Power Quality in Older Women

Previous reports on the effects of strength training (ST) on muscle power did not report how the training affected power per unit of the muscle involvement (muscle power quality, MPQ), or peak movement velocity (PV). The expression of peak power normalized for muscle volume allows better understanding of potential mechanisms for training-induced adaptations. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. METHODS Sixty-two relatively healthy, previously sedentary older adults (23 older men, 65 ± 1 yr and 39 older women, 66 ± 1 yr) were studied before and after a 10 wk unilateral knee extension ST program. To quantify quadriceps muscle volume (MV), computed tomography (CT) imaging of the trained and untrained thighs was performed. Determination of peak knee extensor power was performed on a customized pneumatic resistance knee extension machine. Velocity and power data were filtered using a 10 Hz, low-pass Butterworth filter to remove sensor noise and obtain peak estimates. RESULTS As a result of the ST program, peak power increased significantly in both men and women at the same absolute (APP; P < 0.001) and relative loads (RPP; P < 0.05). Men had significantly greater increases in APP and RPP than women with ST when covarying for baseline differences (both P < 0.001). However, when each subject was tested at the same absolute load and when peak power was normalized for the muscle volume of the trained knee extensors (i.e., absolute MPQ), women increased their MPQ (P < 0.05), but men did not. Both men and women increased their absolute PV (P < 0.001), but decreased their relative PV significantly with ST (P < 0.01). CONCLUSIONS These data indicate that a moderate-velocity ST program increases muscle power quality in women, but not in men, suggesting that in contrast to men, women increase peak power with ST through adaptations other than muscular hypertrophy. Supported by NIH Grants R01 AG-4-2148 and AG-1620501 and NIH training grant T32AG00219.

Moderate Velocity Strength Training Increases Peak Muscle Power Quality in Older Women

Previous reports on the effects of strength training (ST) on muscle power did not report how the training affected power per unit of the muscle involvement (muscle power quality, MPQ), or peak movement velocity (PV). The expression of peak power normalized for muscle volume allows better understanding of potential mechanisms for training-induced adaptations. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. METHODS Sixty-two relatively healthy, previously sedentary older adults (23 older men, 65 ± 1 yr and 39 older women, 66 ± 1 yr) were studied before and after a 10 wk unilateral knee extension ST program. To quantify quadriceps muscle volume (MV), computed tomography (CT) imaging of the trained and untrained thighs was performed. Determination of peak knee extensor power was performed on a customized pneumatic resistance knee extension machine. Velocity and power data were filtered using a 10 Hz, low-pass Butterworth filter to remove sensor noise and obtain peak estimates. RESULTS As a result of the ST program, peak power increased significantly in both men and women at the same absolute (APP; P < 0.001) and relative loads (RPP; P < 0.05). Men had significantly greater increases in APP and RPP than women with ST when covarying for baseline differences (both P < 0.001). However, when each subject was tested at the same absolute load and when peak power was normalized for the muscle volume of the trained knee extensors (i.e., absolute MPQ), women increased their MPQ (P < 0.05), but men did not. Both men and women increased their absolute PV (P < 0.001), but decreased their relative PV significantly with ST (P < 0.01). CONCLUSIONS These data indicate that a moderate-velocity ST program increases muscle power quality in women, but not in men, suggesting that in contrast to men, women increase peak power with ST through adaptations other than muscular hypertrophy. Supported by NIH Grants R01 AG-4-2148 and AG-1620501 and NIH training grant T32AG00219.

Age differences in knee extension power, contractile velocity, and fatigability

The purposes of this study were to examine age and gender differences in knee extensor strength, power, and fatigue using open- and closed-chain testing procedures. We tested the hypothesis that specific strength (strength/unit muscle mass) would not differ by age, whereas age differences in specific power and fatigue would remain consequent to blunted maximal contractile velocity. Skeletal muscle performance was examined in 28 young (26.9 +/- 0.7 yr) and 24 older (63.6 +/- 0.8 yr) men and women. Assessments included one-repetition maximum strength for knee extension, leg press, and squat; concentric knee extensor peak power, velocity, and fatigability; and sit-to-stand power, fatigability, and relative neural activation (electromyograph activity during sit-to-stand movement normalized to electromyograph activity during isometric maximum voluntary contraction). Thigh lean mass (TLM; kg) was assessed by dual-energy X-ray absorptiometry. Specific strength (N/kg TLM) and specific power (W/kg TLM) were estimated by dividing absolute values by TLM. Age differences in specific strength were observed for knee extension only (young, 41.2 +/- 1.0 N/kg TLM; older, 32.4 +/- 1.0 N/kg TLM; P < 0.05). Adjustment for TLM did not negate age differences in knee extension specific power (25-41% lower in older; P < 0.05) across loads tested. Older adults experienced fatigue across 10 repetitions of knee extension as peak velocity fell by 24% (P < 0.05). Deficits in concentric power persist after adjustment for TLM as maximum contractile velocity falls markedly with aging. Older adults are less capable of sustaining maximum concentric velocity during repetitive contractions. These findings suggest that velocity impairments are a possible contributor to mobility loss and falls risk among older adults. Interventions for improving contractile velocity should be pursued.

Relationship between postural balance and knee and toe muscle power in young women.

Muscle power in the lower extremities and body sway were measured in 57 healthy young women volunteers in their 20's. Body sway was measured with a stabilimeter for 30 sec during two-leg standing, and for 10 sec during one-leg standing with the eyes open or closed, alternating between right and left legs (5 times each). The measured parameters of body sway were locus length per time unit, locus length per environmental area, environmental area, rectangle area, root mean square area, and the ratio of sway with eyes closed to sway with eyes open. Knee flexor and extensor power and toe flexor and abductor power were the measures representing lower extremity muscle power. The increase in sway with the eyes closed was more marked during one-leg standing than two-leg standing, as expected. We found that 36 of 57 subjects (62%) were unable to maintain one-leg standing with their eyes closed, and this failure correlated with marked body sway (P = 0.0086). Many subjects had one leg that was classified as stable and the other leg classified as unstable. Clearly, testing of both legs alternately with eyes closed is necessary to measure the full range of sway in subjects. Lower extremity muscle power did not appear to be the dominant factor in maintaining balance in these young subjects.

Gender-specific knee extensor torque, flexor torque, and muscle fatigue responses during maximal effort contractions.

The purpose of this study was to examine gender differences in knee extensor and flexor peak torque, work, power, and muscle fatigue during maximal effort isokinetic contractions. Subjects included 19 healthy male and 20 healthy female volunteers. Following a dynamic warm-up period, subjects performed 30 reciprocal, concentric maximal knee extension and flexion contractions at a pre-set angular velocity of 3.14 rad x s(-1) on the Biodex Isokinetic Dynamometer. Values for knee extensor peak torque, work, and power were calculated for each repetition over an angular displacement of 1.05 rad for each repetition. The single highest repetition value for knee extensor and flexor peak torque, work, and power was then calculated relative to body mass (N x m x kg(-1), J x kg(-1), W x kg(-1)) and allometric-scaled (N x m x kg(-) (n), J x kg(-) (n), W x kg(-) (n)) units. The allometric-scaled units were derived from a log-log transformation and linear regression analysis to calculate the exponent to which body mass is raised. The rate of quadriceps femoris muscle fatigue was calculated as the decline in each isokinetic variable by the linear slope from the single highest repetition value through the 30th repetition, and by two different fatigue indexes. The results demonstrate higher knee extension and flexion peak torque, work, and power in absolute, relative, and allometric-scaled units for males compared to females. Males exhibited higher fatigue rates for both muscle groups of each isokinetic variable than females, as described by the slope and the fatigue index, except when adjusted for peak values via analysis of covariance. The findings suggest that during maximal-effort muscle contractions, males exhibit a higher susceptibility to muscle fatigue than females, a phenomenon that may be related to an inherent ability to generate higher knee extensor and flexor torque.

Relationship between Nonparetic Side Knee Extensor Power and Walking Ability among Acute Hemiplegic Patients

Relationship between Nonparetic Side Knee Extensor Power and Walking Ability among Acute Hemiplegic Patients

Gait adaptations in patients with chronic posterior instability of the knee

Objective. A retrospective analysis was performed to assess gait in individuals with a long history of posterior knee instability. Design. Descriptive study. Background. There are few studies in the literature concerning evaluation of the biomechanics of the knee in patients with knee posterior instability. Methods. Nine individuals with posterior knee instability and a matched control group of uninjured subjects were tested in regards to knee kinematics and kinetics while walking and ascending and descending stairs. The mean follow up time for the individuals with posterior instability was 11.1 years. Individual satisfaction with the knee was measured by having participants complete the Flandry (also known as Hughston Clinic) self-assessment questionnaire. Results. It was found that patients with knee posterior instability who indicated a higher level of satisfaction on the Flandry score walked in a manner that demonstrated greater peak knee extensor torque during stance phase, while less satisfied patients with knee posterior instability demonstrated lower peak knee extensor torque. There was a significant correlation between the self-assessment score and the peak knee extensor torque during level walking ( P=0.003). During stair ascent and descent, patients with posterior instability averaged lower knee extensor torque and power than the control subjects, but those differences were only statistically significant in power while descending stairs ( P=0.048). Conclusions. Individuals with chronic knee posterior instability modify their gait, and the adaptation can be predicted based upon the individuals self-assessment of their knee using the Flandry questionnaire. Relevance These data suggest that gait retraining may be a valuable addition to the traditional muscle strengthening programs, which are commonly used during conservative management of knee posterior instability.

Anticipatory locomotor control for obstacle avoidance in mid-childhood aged children.

The present work explored the anticipatory locomotor adjustments during obstacle avoidance by eight children aged 7--9 years. Analyses involved kinematic, kinetic and muscle mechanical power patterns at each lower limb joint, as well as electromyographic data from five muscles. The children demonstrated adult-like limb displacements and general dynamic strategies for obstacle clearance. However, when normalized to body mass, amplitudes of certain muscle power bursts related to anticipatory locomotor adjustments were decreased from those reported in the literature for adults, and an absence of the usual antagonistic knee extensor power burst at the end of the stance phase was frequently observed. The data suggest that the expression of anticipatory locomotor adjustments is still maturing during mid-childhood.

Effect of patellar taping on knee kinetics of patients with patellofemoral pain syndrome.

Single-group repeated measures examining patients with patellofemoral pain syndrome. To examine the effect of McConnell patellar taping on single-leg vertical jump height and knee extensor moment and power during a vertical jump and lateral step-up. Patellar taping is used by clinicians in an attempt to maximize knee extensor function during sporting activities and rehabilitation of patients with patellofemoral pain syndrome. No studies have examined the effect of patellar taping on vertical jump height and knee extensor moment and power during a maximal vertical jump or lateral step-up. Fourteen women (24.4 +/- 5.8 years) with unilateral patellofemoral pain performed a single-leg vertical jump and lateral step-up during 4 knee conditions: patellar tape, placebo tape, no tape, and the uninvolved knee. Maximal knee extensor moment, knee power, and vertical jump height were measured for each condition using a force platform and motion analysis system. Analysis of variance and post hoc analyses revealed a main effect for knee condition. The patellar tape condition resulted in a greater knee extensor moment (1.57 +/- 0.32 N.m/kg) and power (3.47 +/- 0.67 W/kg) than did the no-tape (1.31 +/- 0.39 N.m/kg and 2.79 +/- 1.21 W/kg) and placebo tape (1.33 +/- 0.30 N.m/kg and 2.70 +/- 0.99 W/kg) conditions. Additional analyses showed that the vertical-jump height was significantly greater in the uninvolved lower extremity (25.69 +/- 2.66 cm) compared with the patellar tape (23.33 +/- 4.22 cm), placebo tape (23.08 +/- 4.20 cm), and no-tape (23.45 +/- 4.54 cm) conditions. The patellar tape condition did not show a different vertical jump height than the placebo or no-tape conditions. These results suggest that patellar taping compared with no tape may improve the knee extensor moment and power during weight-bearing activities such as the lateral step-up exercise and the vertical jump.