Intra‐ and intermuscular variation in human quadriceps femoris architecture assessed in vivo

Abstract

Despite the functional importance of the human quadriceps femoris in movements such as running, jumping, lifting and climbing, and the known effects of muscle architecture on muscle function, no research has fully described the complex architecture of this muscle group. We used ultrasound imaging techniques to measure muscle thickness, fascicle angle and fascicle length at multiple regions of the four quadriceps muscles in vivo in 31 recreationally active, but non-strength-trained adult men and women. Our analyses revealed a reasonable similarity in the superficial quadriceps muscles, which is suggestive of functional similarity (at least during the uni-joint knee extension task) given that they act via a common tendon. The deep vastus intermedius (VI) is architecturally dissimilar and therefore probably serves a different function(s). Architecture varies significantly along the length of the superficial muscles, which has implications for the accuracy of models that assume a constant intramuscular architecture. It might also have consequences for the efficiency of intra-and intermuscular force transmission. Our results provide some evidence that subjects with a given architecture of one superficial muscle, relative to the rest of the subject sample, also have a similar architecture in other superficial muscles. However, this is not necessarily true for vastus lateralis (VL), and was not the case for VI. Therefore, the relative architecture of one muscle cannot confidently be used to estimate the relative architecture of another. To confirm this, we calculated a value of whole quadriceps architecture by four different methods. Regardless of the method used, we found that the absolute or relative architecture of one muscle could not be used as an indicator of whole quadriceps architecture, although vastus medialis, possibly in concert with VL and the anterior portion of VI, could be used to provide a useful snapshot. Importantly, our estimates of whole quadriceps architecture show a gender difference in whole quadriceps muscle thickness, and that muscle thickness is positively correlated with fascicle angle whereas fascicle length is negatively, although weakly, correlated with fascicle angle. These results are supportive of the validity of estimates of whole quadriceps architecture. These data are interpreted with respect to their implications for neural control strategies, region-specific adaptations in muscle size in response to training, and gender-dependent differences in the response to exercise training.

Muscle fascicle shortening behaviour of vastus lateralis during a maximal force–velocity test

“…These characteristics indicate that rectus femoris muscle may play a substantial role in the achievement of high knee joint velocity. However, due to the complexity of the muscular geometry of rectus femoris, muscle fascicle tracking during dynamic contractions of this muscle represents a technical challenge (Blazevich et al 2006;Massey et al 2015). Regardless of this, we are confident that the vastus lateralis shortening velocity is the most representative of all knee extensors muscles behaviour.…”

“…This required using an extrapolation of the visible part of the fascicle to estimate the whole length according to aponeuroses Blazevich et al 2006). However, Finni et al (2003) showed a relatively small error measurement, ranging between 2 and 7% of the vastus lateralis.…”

“…The probe (5-12 MHz, 55 mm) was placed on the skin surface over the muscle belly at 39% of the distance between the greater trochanter and the lateral femoral epicondyle (Blazevich et al 2006). The orientation of the probe followed the recommendations of Benard et al (2009) to obtain the longest muscle fascicles possible.…”

Vastus Lateralis Fascicle Length Changes During Stair Ascent and Descent

“…Two disposable electrodes 3 mm in diameter were placed over the VL at a center-to-center distance of 2 cm, after shaving and cleaning the skin with alcohol to ensure appropriate contact. 2 The EMG electrodes were placed on the distal portion of the VL, just distal to the ultrasound transducer. This placement of the electrodes likely decreased the absolute EMG signal compared to a placement closer to the center of the VL.…”

“…2 Physical Therapist, Cleveland Clinic, Sports Health and Orthopaedic Rehabilitation, Cleveland, OH. 3 Physical Therapist, Ohio University Therapy Associates, Athens, OH.…”