Walking and finger tapping can be done with independent rhythms

Rhythmic movements occur in many aspects of daily life. Examples include clapping the hands and walking. The production of two independent rhythms with multiple limbs is considered to be extremely difficult. In the present study we evaluated whether two different, independent rhythms that involved finger tapping and walking could be produced. In Experiment I, twenty subjects that had no experience of musical instrument training performed rhythmic finger tapping with the right index finger and one of four different lower limb movements; (1) self-paced walking, (2) given-paced walking, (3) alternative bilateral heel tapping from a sitting position, and (4) unilateral heel tapping with the leg ipsilateral to the tapping finger from a sitting position. The target intervals of finger tapping and heel strikes for walking step/heel tapping were set at 375 ms and 600 ms, respectively. The even distribution of relative phases between instantaneous finger tapping and heel strike was taken as the criteria of independency for the two rhythms. In the self-paced walking and given-paced walking tasks, 16 out of 20 subjects successfully performed finger tapping and walking with independent rhythms without any special practice. On the other hand, in the bipedal heels striking and unipedal heel striking tasks 19 subjects failed to perform the two movements independently, falling into interrelated rhythms with the ratio mostly being 2:1. In Experiment II, a similar independency of finger tapping and walking at a given pace was observed for heel strike intervals of 400, 600, and 800 ms, as well as at the constant 375 ms for finger tapping. These results suggest that finger tapping and walking are controlled by separate neural control mechanisms, presumably with a supra-spinal locus for finger tapping, and a spinal location for walking.

Thigh and Psoas Major Muscularity and Its Relation to Running Mechanics in Sprinters

PURPOSE

We aimed to examine the morphological characteristics of the thigh and psoas major muscles in sprinters as well as interrelations among their muscularity, hip joint mechanics, and running speed during maximal running.

METHODS

T1-weighted magnetic resonance images of the thigh and trunk were obtained from 15 male sprinters (best 100-m sprint times, 10.63-11.57 s) and 12 untrained men. From the magnetic resonance images, the volumes of each of the quadriceps femoris and hamstrings, total adductors, sartorius, tensor fasciae latae, gracilis, and psoas major were determined. For sprinters, the kinetic and kinematic data were measured using a three-dimensional motion capture system and force plates during maximal running. The data for one step from the foot strike of the stance leg to that of the swing leg were analyzed. The center of gravity (CG) velocity and hip joint kinetics were quantified.

RESULTS

Compared with untrained men, sprinters had significantly greater thigh muscle volumes of the hip flexors and extensors, total adductors, gracilis, and psoas major, whereas the monoarticular knee extensor and flexor thigh muscle volumes were similar between the two groups. The CG velocity was positively correlated with the hip flexion angular impulse. Only the rectus femoris volume was significantly correlated with the CG velocity and peak hip flexion moment for the swing leg (r = 0.66-0.69).

CONCLUSIONS

The sprinters in this study presented greater muscularity of the thigh and psoas major but not the monoarticular knee extensor or flexor muscles. The rectus femoris, in particular, may play an important role during the swing phase of sprinting.

Neuromuscular Adaptations to Work-matched Maximal Eccentric versus Concentric Training

It is unclear whether the superiority of eccentric over concentric training on neuromuscular improvements is due to higher torque (mechanical loading) achievable during eccentric contractions or due to resulting greater total work.

Stretching Combined with Repetitive Small Length Changes of the Plantar Flexors Enhances Their Passive Extensibility while Not Compromising Strength

Static stretching increases flexibility but can decrease muscle strength; therefore, a method that would avoid the latter has been longed for. In this study, a novel stretching modality was developed that provides repetitive small length changes to the plantar flexor muscles undergoing passive static stretching (minute oscillation stretching). We investigated the effects of minute oscillation stretching on muscle strength and flexibility and its continuance. Isometric plantar flexion strength and maximal ankle joint dorsiflexion angle (dorsiflexion range of motion) were measured in 10 healthy young men (22 ± 2 years) before (pre) and immediately after (post) 3 types of stretching: static stretching, minute oscillation stretching at 15 Hz, and no intervention (control). The dorsiflexion range of motion was also measured at 15, 30, and 60 min post-stretching. Elongation of the medial gastrocnemius and Achilles tendon was determined by ultrasonography. Plantar flexion strength significantly decreased by 4.3 ± 3.5% in static stretching but not in minute oscillation stretching. The dorsiflexion range of motion significantly increased both in static stretching (7.2 ± 8.1%) and minute oscillation stretching (11.2 ± 14.6%), which was accompanied by a significantly larger muscle elongation but not tendon elongation. Elevated dorsiflexion range of motion was maintained until 30 min after minute oscillation stretching, while levels returned to baseline (pre-intervention) 15 min after static stretching. All variables remained unchanged in the control condition. In conclusion, minute oscillation stretching improves extensibility of the muscle belly without decreasing strength. Furthermore, the augmented flexibility to a similar extent to static stretching is retained for 30 min in minute oscillation stretching and within 15 min in static stretching.

Morphological and mechanical properties of the human triceps surae aponeuroses taken from elderly cadavers: Implications for muscle-tendon interactions

The human triceps surae (two gastrocnemii and soleus) has aponeuroses in the proximal and distal aspects, the latter of which insert into the calcaneus by sharing the common Achilles tendon. These tendinous tissues are known to have elasticity and upon muscle contraction the aponeurosis is stretched both longitudinally (along the muscle’s line of action) and transversely. Higher aponeurosis transverse deformability has been documented, but there is a paucity of information on the morphology and mechanical properties of human aponeurosis. This study aimed to identify morphological and mechanical characteristics of the human triceps surae aponeuroses. Twenty-five triceps surae muscle-tendon units were procured from 13 human donors (formalin fixed, 6 males, 7 females) aged 67–91 years. Specimens of aponeuroses were excised from the eight regions (posterior and anterior regions of the gastrocnemius medialis and lateralis, medial and lateral parts of soleus; proximal, middle, and distal sites each, 2–4 cm × 2–4 cm). Aponeurosis thickness was measured using a digital caliper. Uniaxial tensile tests were implemented to determine the mechanical properties of specimens loaded longitudinally (along the muscle’s line of action) and transversely. The aponeurosis thickness showed significant differences between muscles and sites, while Young’s modulus showed direction-dependent (longitudinal vs. transverse) differences within sites. Results show different morphology and mechanical properties of aponeuroses between synergist muscles. The reason for site-dependent differences in stiffness is due to a reduced aponeurosis thickness rather than a reduction in the material property. The anisotropic elastic feature (differences between longitudinal and transverse directions) of the aponeuroses was more pronounced than previous in vivo findings, suggesting inherent material design of the aponeurosis that matches three-dimensional contractile behavior of muscle fibers.

Knee extensor muscular activity estimation during different walking patterns: flat normal and brisk walking, stair climbing

Preserving mobility, the ability to keep a correct posture and dynamic balance in order to walk properly, is fundamental to maintain autonomy in daily life. Based on the correlation between muscle groups and autonomy, previous research has suggested that maintaining muscular tone in knee extensors is critical. Continuous training of knee extensors during aging is therefore essential to maintain independence. In this work, it is hypothesized that it is possible to estimate knee extensor activity only from IMU data based on a simple lower limbs model. The accuracy of the knee extensor activity estimation algorithm has been tested using sEMG measurements as control data on three different walking patterns: normal walk, fast walk and stair climbing. Estimated knee torque area and measured muscular activity for each step were compared confirming a high estimation accuracy with a correlation efficient R=0.80. Moreover, muscular activity can be divided based on intensity in three groups of statistically significant difference confirmed by the Steel-Dwass method. Future works should test the usability of the algorithm for different walking patterns, and use the collected data and the refined algorithm to implement a smart resistive device to increase knee extensor exertion during each walking pattern to the level necessary for sufficient extensor training.

Immunohistochemical Analysis of Human Lung Cancers with Anti-ras p21 Monoclonal Antibodies

The expression of ras oncogene product p21 in human malignant pleurisy and primary lung cancer was studied immunocyto-histochemically with monoclonal antibodies (MoAbs) rp-28 and rp-35 against ras p21. In pleural effusion cells, cancer cells revealed more intensively positive reaction with MoAb rp-35 than with MoAb rp-28, especially in the plasma membrane, and no positive reaction was obtained in any kind of inflammation cells with the exception of faintly positive reaction in the cytoplasm of macrophages.

In primary lung cancers, well or moderately differentiated adenocarcinoma tissues showed higher reactivity with MoAb rp-28 than those of poorly differentiated adenocarcinoma or any other histological subtype of lung cancer. With MoAb rp-35, intensively positive reaction was obtained in most of cases with all different histological subtypes of lung cancer. The staining in cancer cells was usually localized intensively to the plasma membrane and weakly to the cytoplasm with both MoAbs. Normal bronchial epithelial and glandular tissues showed only cytoplasmic staining. These two MoAbs, especially MoAb rp-35, may be useful in clinicopathological applications for the diagnosis of malignant pleurisy and primary lung cancer.