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PubMed1998

Quantitative study of the quadriceps muscles and trochlear groove geometry related to instability of the patellofemoral joint.

This was a quantitative study of the major anatomical structures associated with instability of the patellofemoral joint: the quadriceps muscles and the femoral trochlear groove. The attachments of the muscles to the patella, their lines of action, and their relative sizes (physiological cross-sectional areas) were found. On the basis of the physiological cross-sectional areas, it was estimated that the central muscles-the rectus femoris and vastus intermedius-contributed 35% of the quadriceps strength, with 40% from the vastus lateralis and 25% from the vastus medialis. The vastus lateralis had the most variable results, with the ratio of the lateralis to the medialis ranging from 0.90 to 2.18; this may be associated with patellar instability. Both the long and oblique parts of the vastus medialis were more oblique than the corresponding parts of the vastus lateralis. Photographic "skyline" views of the trochlear groove produced data on the sulcus angle and ratio of depth to width. The data showed that the trochlear groove did not deepen in the area contacted by the patella with progressive knee flexion (p > 0.53), contrary to popular belief. These data are useful for objective analysis of patellofemoral stability and related surgical interventions.

Aged↗
PubMed1992

Quadriceps muscle activity in women runners with and without patellofemoral pain syndrome.

The purpose of this study was to determine whether there was a difference in the electromyographic (EMG) patterns of the quadriceps muscles in women runners diagnosed with patellofemoral pain syndrome (PFPS) compared to the quadriceps activity of women runners free of knee pain and with normal lower extremity alignment. Linear envelope EMGs from vastus medialis, vastus lateralis, and rectus femoris, together with a footswitch signal, were recorded as each subject ran on a treadmill at 80% of their normal running pace and at 12km/h. Each stride period was normalized to 100%, then the linear envelopes for ten trials were ensemble averaged to achieve a mean ensemble for each muscle from each subject. Subsequently, the ensembles for each subject were normalized by dividing by the maximum EMG per cycle; they were then averaged across subjects to obtain the grand mean ensembles of each muscle for each group. Comparisons between the experimental and control groups at both speeds showed that nowhere during the stride cycle did the mean EMG levels of the two groups differ by more than two standard deviations. It was concluded that any changes in the running pattern of the runners with patellofemoral pain syndrome could not be detected by changes in the EMG patterns.

Adult↗
PubMed2005

Assessment of skeletal muscle fatigue in men with coronary artery disease using surface electromyography during isometric contraction of quadriceps muscles.

OBJECTIVE: To evaluate whether using surface electromyography to assess skeletal muscle fatigue during an isometric exercise has the potential to be clinically useful in patients with coronary artery disease (CAD). DESIGN: Double sample comparative study. SETTING: Cardiac rehabilitation service in France. PARTICIPANTS: Sixteen men with documented CAD and 9 age-matched healthy men. INTERVENTIONS: Assessment of quadriceps skeletal muscle fatigue on an isokinetic apparatus with surface electromyography measurements and a symptom-limited exercise test in a laboratory. MAIN OUTCOME MEASURES: The maximal voluntary isometric force (MVIF) of the quadriceps was quantified as a measure of muscle strength and isometric endurance was defined as the time required to sustain a contraction at 50% of MVIF until exhaustion. Surface electromyography signals were recorded from the vastus lateralis, rectus femoris, and vastus medialis during isometric endurance. The root mean square (RMS) and the median frequency (MF) were directly calculated on a computer and then normalized (as a percentage of the initial value). RESULTS: Muscle strength did not differ significantly between the patients with CAD and the healthy subjects (229+/-21N/m vs 228+/-52N/m), but isometric endurance was reduced (64+/-17s vs 90+/-7s, P <.01). The RMS values showed a significantly higher increase in the healthy subjects versus the patients with CAD for the vastus lateralis and vastus medialis ( P <.001). The MF values were significantly lower for the vastus lateralis, rectus femoris ( P <.01), and vastus medialis ( P <.05) in patients with CAD compared with the healthy subjects. CONCLUSIONS: Skeletal muscle fatigue occurs sooner in men with CAD relative to matched healthy men, despite similar muscle strength. This finding may be the result of an abnormality of skeletal muscle function and may play an important role in measuring functional capacity. In addition, it may be a useful tool to assess the efficacy of cardiac rehabilitation interventions.

Coronary Artery Disease↗
PubMed1996

Surface action potentials related to torque output in paraplegics' electrically stimulated quadriceps muscle.

We recorded in 15 complete paraplegic patients the torque output and the surface action potentials (SAP) produced by the electrically stimulated quadriceps muscle during an isometric contraction lasting 126 s. We studied the evolution during the test of the peak to peak amplitude, the latency from the onset of stimulation, the rising time to peak, the peak to peak duration, the area of the recorded SAPs and we tried to relate those data to the torque production. Results were extremely different among patients but the general behaviour facing this test was comparable. After a short increase the mechanical output decreased and reached a plateau (range from 7.13 to 53.5% of initial value). The peak to peak amplitude first increased and then decreased, and was not related to the torque production. The latency, the rising time to peak and the peak to peak duration continuously increased to a maximum and then plateaued or slightly decreased after different courses of time. The latency from the onset of stimulation was less affected by the test than the rising time to peak and the peak to peak duration. Therefore, the nerve conduction velocity and the neuromuscular junction transmission did not vary to a great extent compared to the muscle fibre conduction velocity. The area of the rectified SAPs first increased and then decreased and was not related to the torque decrease.

Action Potentials↗
PubMed1997

Glomus tumor with diffuse infiltration of the quadriceps muscle: a case report.

A case of a diffuse growing glomus tumor with interstitial infiltration of the musculus vastus medialis and intermedius (quadriceps muscle) in a 21-year-old woman is reported. The tumor was diagnosed by needle biopsy and then removed with wide margins. The typical histological appearance and the immunohistochemical findings in the resected specimen confirmed the diagnosis. Histogenesis and the biological behavior of glomus tumors are discussed.

Adult↗
PubMed1993

Fibre areas and histochemical fibre types in the quadriceps muscle of paraplegic subjects.

With the advent of functional electrical stimulation (FES) there is the possibility of paraplegic patients regaining some degree of locomotor activity. It is of interest to document the changes in composition histochemistry and size of muscle fibres in such patients both before and after such therapy. We have examined biopsy specimens from quadriceps muscles obtained from 7 male patients, age range 24-47 years, who had been paraplegic for times ranging from 11 months to 9 years and we report the histochemical appearance of the muscle the fibre type composition and the mean fibre areas. In 5 of the 7 subjects there was a marked or complete predominance of fibres which stained as type 2 with the ATPase reaction at pH 9.4. At acid pH these fibres were seen to be predominantly 2B (fast fatigable). The 2 subjects who had been paralysed for the shortest periods had proportions of type 1 fibres which were relatively well preserved. The mean fibre areas of type 2 fibres were below the normal range (2500-7500 microns 2) in every case as were the type 1 fibres in the 4 patients in which these were still present. There was no relationship between the length of time the patient had been paralysed and the mean fibre areas which suggests that atrophy occurs fairly quickly following loss of voluntary control and precedes the loss of type 1 characteristics. Our findings provide an explanation for the rapid onset of fatigue in paraplegic patients taking part in FES programmes since muscles deficient in type 1 fibres will be unable to maintain force for any length of time.

Adult↗
PubMed1991

Ultrasound imaging of the quadriceps muscle in elderly athletes and untrained men.

Ultrasound (US) technique was applied to measure the thickness, cross-sectional area (CSA), and internal structure of the quadriceps muscle in 70- to 80-year-old endurance and power athletes and untrained men. Isometric knee extension strength was higher in the power athletes than in the other groups. The mean values for thickness and CSA did not differ between the athletes and the untrained men. The intensity of the intramuscular echo was, however, lower and the echo reflected from the connective tissue septa and bone was higher in the athletes than in the untrained men. Both the CSA and internal structure of the muscle group correlated significantly with muscle strength and number of training kilometers per year. The results suggest that long-term training maintains the muscle architecture and counteracts the age-related replacement of contractile tissue by other tissues such as fat.

Aged↗
PubMedDate not supplied

The effect of joint-compressive load and quadriceps muscle force on knee motion in the intact and anterior cruciate ligament-sectioned knee.

To determine the effect of an externally applied joint-compressive load and a quadriceps muscle force on knee motion, we tested nine intact cadaveric knees and four knees after sectioning of the anterior cruciate ligament. Anteroposterior translation was measured at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 90 degrees of knee flexion after the application of an anteroposterior force of 100 N, a joint-compressive load of 0, 111, 222, 333, or 444 N, and a quadriceps force of 0 or 133 N. Both a joint-compressive load and a quadriceps force significantly decreased total anteroposterior translation by as much as 50% to 66% in intact knees and 42% to 71% in anterior cruciate ligament-sectioned knees. A substantial anterior translation was also found with the application of a joint-compressive load or a quadriceps force and no anterior force. We termed this translation an anterior neutral-position shift. The anterior neutral-position shift was significantly greater in the ligament-sectioned knees compared with the intact knees, so much so that at flexion angles greater than 15 degrees, the application of a 100-N posterior force could not translate the tibia to the most anterior position achieved in the intact knee with a 100-N anterior force.

Aged↗
PubMed2000

Quadriceps muscle function in relation to habitual physical activity and VO2max in men and women aged more than 65 years.

The relationship of quadriceps maximal muscle power (Pmax), corresponding optimal shortening velocity (v(opt)), and relative fatigability (Pmax%D) to maximal oxygen uptake (VO2max) and habitual physical activity (PA) was examined in healthy community-dwelling subjects (29 women and 25 men) aged more than 65 years old. PA was evaluated by a questionnaire and expressed using two activity indices: mean habitual daily energy expenditure (MHDEE) and the daily energy expenditure corresponding to leisure time sports activities (Sports Activity). In women, Pmax correlated positively with VO2max (r = .56) and with Sports Activity (rho = .41). Both Sports Activity and Pmax were significant independent predictors of VO2max and accounted for 62% of variance in VO2max. In men, v(opt) was significantly negatively related to MHDEE (r = -.59) and to Sports Activity (rho = -.40). Neither in women nor in men was Pmax%D correlated with VO2max or PA indices. The different relationship of Pmax and v(opt) with VO2max and PA indices suggests that habitual PA may be sufficient in active older women, but not in men, to positively influence quadriceps muscle function. These gender differences may suggest different approaches in exercise programming for elderly women and men.

Aged↗
PubMed2004

The Protonics Knee Brace Unloads the Quadriceps Muscles in Healthy Subjects.

OBJECTIVE: The Protonics brace is a functional resistance brace designed for rehabilitative use in patients with patellofemoral pain syndrome. Our objective was to determine whether the Protonics brace altered quadriceps muscle activity or knee mechanics in healthy subjects. DESIGN AND SETTING: We used a within-subjects design in a laboratory setting. SUBJECTS: Nineteen recreationally active college students (10 females, 9 males; age = 22.6 +/- 2.8 years; height = 172 +/- 9.0 cm, mass = 69.7 +/- 12.5 kg) with no history of patellofemoral pain syndrome. MEASUREMENTS: A standard-length Protonics brace was fit to each subject's leg. Surface electromyography of the vastus medialis obliquus, vastus lateralis, and rectus femoris muscles was recorded during a lateral step-down exercise. Lower extremity kinematics and ground reaction force were assessed during stair descent. Subjects performed both tasks under 4 conditions: no brace and brace with low, medium, and high resistance. Electromyography values were normalized to a maximum voluntary isometric contraction. The brace moment was determined by passive testing in an isokinetic dynamometer. Changes in the subject's muscular knee-extension moment were determined by subtracting the extension moment provided by the brace from the total knee-extension moment calculated from motion and force data using an inverse dynamics approach. RESULTS: Vastus medialis obliquus activity in the brace at the low- and medium-resistance settings was significantly lower than that measured without the brace. Vastus lateralis activity while wearing the brace at medium resistance was significantly less than in the absence of the brace. Regardless of brace setting, vastus medialis obliquus and vastus lateralis activity in the descending phase of the exercise was less than during the ascending phase. A significant interaction was noted between brace setting and phase of the step-down exercise for rectus femoris activity. Significantly less activity was seen in the descending phase than in the ascending phase. Post hoc testing indicated that, in the descending phase, less activity was demonstrated with the brace at the medium and high settings than at the low setting. Muscle activity at the high setting and activity at low resistance were also significantly less than when the brace was not worn in the ascending phase. Knee flexion and extension moment during stair descent were significantly less at the higher resistance settings. CONCLUSIONS: Wearing the Protonics brace at moderate or high resistance during the lateral step-down exercise produced less quadriceps activity compared with not wearing the brace. The knee extensor mechanism was unloaded when the brace was worn during stair descent. These findings indicate that the Protonics brace may unload the quadriceps and therefore decrease the load on the patellofemoral joint.

Journal Article↗
PubMed1998

Measurement of quadriceps muscle strength and bulk in juvenile chronic arthritis. A prospective, longitudinal, 2 year survey.

OBJECTIVE: In a prospective survey over a 2-year period we studied strength and bulk of the quadriceps muscle in the thighs of children with juvenile chronic arthritis (JCA). METHODS: Every third month for 2 years we measured isometric muscle strength in knee extensors with a hand-held dynamometer in 20 children with JCA. Ultrasound equipment was used to measure thigh muscle bulk. A joint evaluation was made using a standard severity score. The children had their ordinary medical treatment and physiotherapy during the observation period. RESULTS: Children with high severity scores in the knee or hip had least strength and muscle bulk. In the 4 children with the highest severity scores muscle strength was reduced to half of that expected. In 10 of the children there were clear variations in severity scores during the study period, for either better or worse. In these children an increase in the severity score correlated significantly with reduction in muscle strength and bulk (p < 0.05). The muscle strength and bulk changed in parallel in these children. Other factors, although not independent, such as polyarticular JCA, long duration of disease, and steroid treatment, also reduced muscle strength. CONCLUSION: The presence and intensity of local arthritis is one important factor affecting muscle function in JCA. Normal muscle strength and bulk is rapidly lost near an inflamed joint. It is difficult to maintain or achieve normal muscle function in the presence of active arthritis despite medical and physical treatment. We assume that the muscle weakness is in part caused by atrophy of the muscle, which is influenced by local arthritis.

Adolescent↗
PubMed2002

Tourniquet-induced restriction of the quadriceps muscle mechanism. Fact or fiction?

Many knee surgeons flex the knee and sometimes also extend the hip before inflating a tourniquet on the thigh. This practice stems from the belief that these manoeuvres prevent excessive strain on the quadriceps during surgery, the assumption being that movement of the muscle is restricted by an inflated tourniquet. We therefore examined, using ultrasound, the movement of the quadriceps muscle above and below the tourniquet before and after inflation. We applied a tourniquet of standard size to the thigh of five volunteers for approximately five minutes. A bubble of air was injected into the quadriceps muscle above the tourniquet and was the proximal point of reference. The musculotendinous junction was the distal point. The movement of the reference point was measured by ultrasound before and after inflation of the tourniquet. Each measurement was repeated with either the knee flexed and the hip extended, or the hip flexed and the knee extended. The mean and standard deviation were recorded. Before inflation the mean amount of passive movement was 1.1 +/- 0.13 cm proximal and 4.0 +/- 0.08 cm distal to the tourniquet, with a range of movement of the knee of 0 degrees to 137 degrees (6.7 degrees). After inflation the mean passive movement was 1.0 +/- 0.07 cm proximal and 4.0 +/- 0.08 cm distal to the tourniquet with a range of 0 degrees to 132 degrees (+/- 7.6 degrees). The ultrasound findings therefore have shown no evidence of restriction of the quadriceps muscle by an inflated tourniquet.

Adult↗
PubMed2003

Quadriceps muscle strength and voluntary activation after polio.

Quadriceps strength, maximal anatomical cross-sectional area (CSA), maximal voluntary activation (MVA), and maximal relaxation rate (MRR) were studied in 48 subjects with a past history of polio, 26 with and 22 without postpoliomyelitis syndrome (PPS), and in 13 control subjects. It was also investigated whether, apart from CSA, MVA and MRR were determinants of muscle strength. Polio subjects had significantly less strength, CSA, and MRR in the more-affected quadriceps than control subjects. MVA was reduced in 18 polio subjects and normal in all controls. PPS subjects differed from non-PPS subjects only in that the MVA of the more-affected quadriceps was significantly lower. Both CSA and MVA were found to be associated with muscle strength. Quadriceps strength in polio subjects was dependent not only on muscle mass, but also on the ability to activate the muscles. Since impaired activation was more pronounced in PPS subjects, the new muscle weakness and functional decline in PPS may be due not only to a gradual loss of muscle fibers, but also to an increasing inability to activate the muscles.

Adult↗
PubMed1991

Biphasic expression of slow myosin light chains and slow tropomyosin isoforms during the development of the human quadriceps muscle.

Using a two-dimensional electrophoresis technique coupled with sensitive silver staining, we have investigated the chronology of appearance of the myosin light chain and tropomyosin isoforms during early stages of human quadriceps development. Our results show that slow myosin light chains and the slow tropomyosin isoform are not detected at 6 weeks of gestation. These isoforms transiently appear between 12.5 weeks and 15 weeks of gestation and then disappear. The slow myosin light chains are re-expressed at 31 weeks of gestation and the slow tropomyosin isoform later at 36 weeks of gestation, and normally remained expressed into the adulthood. Our study thus reveals a biphasic expression of the slow myosin light chains and the slow tropomyosin isoform in developing human quadriceps muscle.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1983

Progressive resistance exercise training of the hypotrophic quadriceps muscle in man. The effects on morphology, size and function as well as the influence of duration of effort.

The effects of progressive resistance exercise (PRE) training for 4 weeks on the hypotrophic quadriceps muscle were investigated in 23 young healthy male soccer players, who had been immobilized in a plaster cast 4-6 weeks after knee ligament injuries. The subjects were allocated to two training regimes where the injured leg was trained for periods of varying duration, whereas the intensity and frequency of exercise were alike in the two groups. However no significant differences were detected between the two training groups. In the whole material the lean thigh volume of the injured leg increased from 4.09 to 4.47 litres (p less than 0.001), whereas the fat component of the thigh was unchanged. The dynamic strength (1 RM) of the injured leg increased from 14.0 kg to 27.0 kg and amounted to 87% of the control leg after 4 weeks of training. At this time the maximum isometric strength amounted to 114 Nm, which was 63% of strength in the control leg. Succinate dehydrogenase (SDH) in homogenates of muscle biopsy sample increased (i.e. 20%, p less than 0.05) to the same level as found in the control leg. No changes in phosphofructokinase (PFK) were observed. The type I fibre distribution was lower in the immobilized leg than in the control leg. These results indicate that, following muscular hypotrophy resulting from 4-6 weeks of immobilization, dynamic exercise can restore the oxidative potential, whereas the size and strength are only partly recovered.

Adolescent↗
PubMed2003

Quadriceps muscles vastus medialis obliques, rectus femoris and vastus lateralis compared via electromyogram bicoherence analysis.

Bicoherence analysis is applied to electromyogram (EMG) data for vastus medialis obliques (VM), rectus femoris (RF) and vastus lateralis (VL) quadriceps muscles of 18 adult male subjects for isometric knee extension exercise. Mean average bicoherence for VM, RF and VL is 30.9 +/- 5.8, 26.0 +/- 1.2 and 25.4 +/- 1.4% respectively and repeated measures ANOVA differentiates the muscles on the basis of average bicoherence (F = 16.2 (1, 17), p = 0.0009, VM cf. VL and F = 15.4 (1, 17), p = 0.0011, VM cf. RF). Prominent regions representative of strong second-order phase coupling between constituent EMG frequencies are identified within VM and RF bicoherence spectra. No such prominent regions are identified for VL which is thought to be less activated than VM during the specified task. Hence, the degree of second-order phase coupling may increase as the level of muscle activation increases. The subject group consists of young (24.0 +/- 0.9 years) and elderly (68.9 +/- 0.9 years) subgroups that cannot be differentiated by standard indices (median and spectral edge frequency) to within p < 0.05 using the Mann-Whitney test. Average bicoherence differentiates the subgroups for RF (T = 9 (8,10), p < 0.005) but not for VM or VL. The application of a bicoherence threshold that takes harmonic amplitude into account graphically differentiates the subgroups for all muscle types. The findings suggest that nonlinear processes play a role within the EMG generation process and support a mechanomyogram bicoherence analysis study that shows nonlinear processes occur within active muscle fibre twitch summation patterns. A potential exists for bicoherence analysis to complement standard EMG frequency analysis techniques.

Adult↗