Pendular Mechanism Research Articles

Stride width and postural stability in frontal gait disorders and Parkinson's disease.

Older adults, as well as those with certain neurological disorders, may compensate for poor neural control of postural stability by widening their base of foot support while walking. However, the extent to which this wide-based gait improves postural stability or affects postural control strategies has not been explored. People with idiopathic Parkinson's disease (iPD, n = 72), frontal gait disorders (FGD, n = 16), and healthy older adults (n = 32) performed walking trials at their preferred speed over an 8-m-long, instrumented walkway. People with iPD were tested in their OFF medication state. Analyses of covariance were performed to determine the associations between stride width and measures of lateral stability control. People with FGD exhibited a wide-based gait compared to both healthy older adults and iPD. An increased stride width was associated with an increase in lateral margin of stability in FGD. Unlike healthy older adults or iPD, people with FGD did not externally rotate their feet (toe-out angle) or shift their center of pressure laterally to aid lateral dynamic stability during walking but slowed their gait instead to increase stability. By adopting a slow, wide-based gait, people with FGD take advantage of the passive, pendular mechanics of walking.

Beakiation: how a novel parrot gait expands the locomotor repertoire of living birds.

Occupation of arboreal habitats poses myriad locomotor challenges, driving both anatomical and behavioural innovations across various tetrapod lineages. Here, we report and biomechanically assess a novel, beak-driven locomotor mode-'beakiation'-by which parrots advance along the underside of narrow arboreal substrates. Using high-speed videography and kinetic analyses, we describe the limb loading patterns and pendular mechanics of beakiation, and compare the biomechanical characteristics of this gait with other suspensory behaviours (namely, forelimb-driven brachiation and inverted quadrupedal walking). We report that the parrot beak experiences comparable force magnitudes (approx. 150% body weight in the normal plane; approx. 50% body weight in the fore-aft plane) to the forelimbs of brachiating primates. Parrot beakiation is also characterized by longer-than-expected pendular periods, similar to observations of gibbon brachiation. However, in terms of mechanical energy recovery, beakiation is typified by lower levels of energetic recovery than brachiating specialists: a product of its slower, more careful nature. The observation of this novel behaviour-which adds to a growing base of literature regarding beak-assisted locomotor strategies in birds-highlights the extraordinary behavioural plasticity of birds, the functional versatility of the avian beak, and the difficulties in reconstructing an animal's locomotor repertoire from morphological characteristics alone.

Pendular mechanism determinants and elastic energy usage during walking of obese and non-obese children.

The mechanical and metabolic responses of walking by obese children are not yet well understood. The objectives of this study were (1) to compare the pendular mechanism (recovery, phase shift by α and β values, and ratio between forward and vertical mechanical work), the maximum possible elastic energy usage and the bilateral coordination during walking between non-obese and obese children, and (2) to verify if the bilateral coordination could contribute to understanding the pendular mechanism and elastic energy usage in these populations. Nine obese (six female, 8.7±0.5years, 1.38±0.04m, 44.4±6.3kg and 24.1±3.50kg/m2 ) and eight non-obese (four female, 7.4±0.5years, 1.31±0.08m, 26.6±2.1kg and 16.4±1.40kg/m2 ) children were analysed during walking on a treadmill at five speeds: 1, 2, 3, 4 and 5km/h. The results indicated that although the mechanical energy response of the centre of mass during walking is similar between obese and non-obese children, the obese children showed a lower pendulum-like mechanism and greater elastic energy usage during level walking. Therefore, obese children seem to use more elastic energy during walking compared to non-obese children, which may be related to their apparent higher positive work production during the double support phase. Finally, bilateral coordination presented high values at slow speeds in both groups and requires further attention due to its association with falls. NEW FINDINGS: What is the central question of this study? Are there any differences of the pendular and elastic mechanisms and bilateral coordination during walking between non-obese and obese children? What is the main finding and its importance? To our knowledge, this study is the first to analyse the mechanical energy usage and the bilateral coordination of obese and non-obese children during walking. Obese children had a lower pendular recovery mechanism and used more elastic energy compared to non-obese children. The bilateral coordination was higher at slow speeds in both groups and requires further attention due to its association with falls.

Artificial Neural Network Detects Hip Muscle Forces as Determinant for Harmonic Walking in People after Stroke.

Many recent studies have highlighted that the harmony of physiological walking is based on a specific proportion between the durations of the phases of the gait cycle. When this proportion is close to the so-called golden ratio (about 1.618), the gait cycle assumes an autosimilar fractal structure. In stroke patients this harmony is altered, but it is unclear which factor is associated with the ratios between gait phases because these relationships are probably not linear. We used an artificial neural network to determine the weights associable to each factor for determining the ratio between gait phases and hence the harmony of walking. As expected, the gait ratio obtained as the ratio between stride duration and stance duration was found to be associated with walking speed and stride length, but also with hip muscle forces. These muscles could be important for exploiting the recovery of energy typical of the pendular mechanism of walking. Our study also highlighted that the results of an artificial neural network should be associated with a reliability analysis, being a non-deterministic approach. A good level of reliability was found for the findings of our study.

Pendular energy transduction in the different phases of gait cycle in post-stroke subjects

MainTo analyze spatiotemporal gait parameters and the body center of mass (CoM) energy transduction at self-selected speed walking in a group of older patients with stroke. MethodsA cross-sectional study, fifteen subjects with 4.06 years post ̵stroke hemiparesis (eleven men and four women) and fifteen healthy subjects (four men and eleven women) participate in this study. Pendulum-like determining variables; Recovery (R) and Congruity percentage (%Cong) were analyzed in addition to immediate pendular re-conversion (Rint) during the phases in which the gait cycle is usually divided in clinical evaluations. ResultsHealthy subjects walked faster that stroke group (p = 0.001). %Cong was significantly higher in post-stroke respect to healthy subjects (p = 0.05). Rint showed significant differences between the groups for all phases (p = 0.05). The relation between speed and R was confirmed, for healthy (r = 0.67, p = 0.006) and post-stroke subjects (r = 0.851, p = 0.001), %Cong y Rint (r = −0.79, p = 0.001), (r = −0.93, p = 0.001) and periods of double support (r = −0.76, p = 0.001), (r = 0.69, p = 0.004) respectively. ConclusionAlteration of pendular mechanism in subjects post-stroke is associated mainly with energy transduction; mechanical energy recovered during double support phases in healthy and post-stroke subjects follows a different trend, in post-stroke subjects, a longer duration of the double support is associated with less energy loss.

Control strategies for rapid, visually guided adjustments of the foot during continuous walking.

When walking over stable, complex terrain, visual information about an upcoming foothold is primarily utilized during the preceding step to organize a nearly ballistic forward movement of the body. However, it is often necessary to respond to changes in the position of an intended foothold that occur around step initiation. Although humans are capable of rapidly adjusting foot trajectory mid-swing in response to a perturbation of target position, such movements may disrupt the efficiency and stability of the gait cycle. In the present study, we consider whether walkers sometimes adopt alternative strategies for responding to perturbations that interfere less with ongoing forward locomotion. Subjects walked along a path of irregularly spaced stepping targets projected onto the ground, while their movements were recorded by a full-body motion-capture system. On a subset of trials, the location of one target was perturbed in either a medial-lateral or anterior-posterior direction. We found that subjects were best able to respond to perturbations that occurred during the latter half of the preceding step and that responses to perturbations that occurred during a step were less successful than previously reported in studies using a single-step paradigm. We also found that, when possible, subjects adjusted the ballistic movement of their center of mass in response to perturbations. We conclude that, during continuous walking, strategies for responding to perturbations that rely on reach-like movements of the foot may be less effective than previously assumed. For perturbations that are detected around step initiation, walkers prefer to adapt by tailoring the global, pendular mechanics of the body.

Energy-saving walking mechanisms in obese adults.

Energy-saving mechanisms are used in human walking. In obese adults the energy cost of walking (Cw) is higher compared with normal-body mass adults. However, the biomechanical factors involved in this extra cost should result in a higher Cw. The aim of this study was to compare energy-saving walking mechanisms [i.e., mechanical energy saved via pendulum (Recovery) and maximum possible elastic energy usage (MPEEu)] and their influence on Cw in obese vs. lean individuals. The net Cw (NetCw), external work (Wext), Recovery, MPEEu, and gait weight transfer duration (gWT) were computed for 13 lean [L; body mass index (BMI) 21.9 ± 1.5 kg/m2] and 13 obese (O; BMI 33.8 ± 2.5 kg/m2) individuals during treadmill walking at five speeds (0.56, 0.83, 1.11, 1.39, 1.67 m/s). No significant difference was found between groups in relative (per kg of body mass) NetCw (P = 0.13). Relative positive Wext was significantly lower at the three fastest speeds (P ≤ 0.003) whereas Recovery was higher at the two fastest speeds (P ≤ 0.01) in O than in L individuals. MPEEu tended to be lower in O than in L (P = 0.06), with significantly lower values in O compared with L at 1.39 and 1.67 m/s (P ≤ 0.017). gWT was significantly shorter in O than in L individuals at 1.67 m/s (P = 0.001). The present results reveal that obese adults rely more on the pendular mechanism than on the storage and release of elastic energy for decreasing the amount of positive Wext and thus limiting the increase in the relative NetCw. NEW & NOTEWORTHY We observed that obese individuals had a lower maximum possible elastic energy usage per kilogram of body mass than their lean counterparts and they may rely more on the pendular mechanism of walking than on the storage and release of elastic energy for decreasing the external mechanical work and thus limiting the increase in the relative net energy cost of walking.

Self-selected walking speed in individuals with transfemoral amputation: recovery, economy and rehabilitation index

Purpose: The aim of this study was to investigate the influence of walking speed on the pendular mechanism, cost of transport, mechanical efficiency and mechanical work in adults with lower-limb amputation, compared to a control group.Methods: Observational, cross sectional study. Ten subjects from an amputee rehabilitation clinic, with the same prosthetic knee and foot and ten healthy subjects were selected to form the experimental and the control group, respectively. Tridimensional kinematics data and oxygen uptake were collected simultaneously at five speeds: the self-selected walking speed (SSWS), two speeds above and below.Results: In the experimental group, the cost of transport was higher than in controls. Contrary to controls, in experimental group the minimum cost of transport and the maximum recovery did not coincide to the SSWS, but were reached at the maximum speed of the protocol. The mechanical efficiency in experimental group was lower, while the external mechanical work and pendular transduction were higher than in controls.Conclusions: The clinical relevance of these results is the concept, also supported by other studies, that interventions headed to increase the SSWS in the experimental group also increase and optimise the energetic economy and the pendulum efficiency of their locomotion.

The Determinants of the Preferred Walking Speed in Individuals with Obesity

Background: The preferred walking speed (PWS), also known as the “spontaneous” or “self-selected” walking speed, is the speed normally used during daily living activities and may represent an appropriate exercise intensity for weight reduction programs aiming to enhance a more negative energy balance. Objectives: The aim of this study was to examine, simultaneously, the energetics, mechanics, and perceived exertion determinants of PWS in individuals with obesity. Methods: Twenty-three adults with obesity (age 32.7 ± 6.8 years, body mass index 33.6 ± 2.6 kg/m²) were recruited. The participants performed 10 min of treadmill familiarization, and PWS was determined. Each subject performed six 5-min walking trials (PWS 0.56, 0.83, 1.11, 1.39, and 1.67 m/s). Gas exchanges were collected and analyzed to obtain the gross energy cost of walking (G_Cw), rated perceived exertion (RPE) was measured using a 6–20 Borg scale, and the external mechanical work (W_ext) and the fraction of mechanical energy recovered by the pendular mechanism (Recovery) were computed using an instrumented treadmill. Second-order least-squares regression was used to calculate the optimal walking speed (OWS) of each variable. Results: No significant difference was found between PWS (1.28 ± 0.13 m/s) and OWS for G_Cw (1.28 ± 0.10 m/s), RPE cost of walking (1.38 ± 0.14 m/s), and Recovery (1.48 ± 0.27 m/s; p > 0.06 for all), but the PWS was significantly faster than the OWS for W_ext (0.98 ± 0.56 m/s; p < 0.02). Multiple regression (r = 0.72; p = 0.003) showed that ∼52% of the variance in PWS was explained by Recovery, W_ext, and height. Conclusion: The main finding of this study was that obese adults may select their PWS in function of several competing demands, since this speed simultaneously minimizes pendular energy transduction, energy cost, and perceived exertion during walking. Moreover, recovery of mechanical work, external work, and height seem to be the major determinants of PWS in these individuals.

The pendular mechanism does not determine the optimal speed of loaded walking on gradients

The pendular mechanism does not act as a primary mechanism in uphill walking due to the monotonic behavior of the mechanical energies of the center of mass. Nevertheless, recent evidence shows that there is an important minimization of energy expenditure by the pendular mechanism during walking on uphill gradients. In this study, we analyzed the optimum speed (OPT) of loaded human walking and the pendulum-like determining variables (Recovery R, Instantaneous pendular re-conversion Rint, and Congruity percentage %Cong). Ten young men walked on a treadmill at five different speeds and at three different treadmill incline gradients (0, +7 and +15%), with and without a load carried in their backpacks. We used indirect calorimetry and 3D motion analysis, and all of the data were analyzed by computational algorithms. Rint increased at higher speeds and decreased with increasing gradient. R and %Cong decreased with increasing gradient and increased with speed, independent of load. Thus, energy conversion by the pendular mechanism during walking on a 15% gradient is supported, and although this mechanism can explain the maintenance of OPT at low walking speeds, the pendular mechanism does not fully explain the energy minimization at higher speeds.

A new integrative approach to evaluate pathological gait: locomotor rehabilitation index

This article reviews the concept of locomotor rehabilitation index (LRI) from the principle of dynamical similarities and the theory of mechanism minimizing the energy expenditure in pathological walking. This index is defined as the percentage ratio between self-selected speed and optimum speed (algebraically LRI = 100 × self-selected speed/optimum walking speed). First, we analyze the mechanical foundations of human walking especially focusing on general size effects. Then, we discuss the descriptive physiology of pendular mechanism, evidencing the path that leads to the view of reductionist and extremely descriptive view of pathological gait. Integrative models, generated by the first evidence presented in our previous papers around the LRI, represent a crucial change of perspective. This model is discussed in details and criticized concerning the ensuing experimental findings. Finally, we discuss the case of Parkinson's disease using the Nordic walking as a neat example of application of LRI on pathological locomotion. To conclude , the concept of LRI is reinforced by the substantial evidence, showing that this new proposal for assessing the gait functionality is extremely promising and should be stimulated in studies that examine the effects of therapies on gait functionality in degenerative diseases.

The connection between anthropometry and gait harmony unveiled through the lens of the golden ratio

In nature, many systems have a harmonic organization due to their fractal structure related to an irrational number called golden ratio. That is a constant proportion found in phases of human gait cycle, and is also found in the lengths of human body segments. In this study we tested if artificial alterations in anthropometric proportions may alter gait proportions. Twenty healthy subjects (29.15±5.66years) were enrolled in this study and asked to walk normally and with special shoes altering their anthropometric proportions. Further, to test if the relationship between gait phases and anthropometry could be due to the pendular mechanism of walking, subjects were also asked to walk with extra masses located on their shanks. Results showed that the artificial alteration of body segment proportions affected the gait ratio based on the proportion of time between stance and swing (p=0.015). Conversely, no changes occurred during walking in weighted condition (p=0.394). These results confirm the connection between anthropometric proportions and gait ratio, and suggest the idea that humans may have evolved into the actual anthropometric proportions for favoring a walking having a golden ratio based harmony, but research is required to verify this hypothesis.

Adaptations to changing speed, load, and gradient in human walking: Cost of transport, optimal speed, and pendulum

It has been observed that the optimal speed (OPT) of human walking is independent of load on level surfaces because of the unaltered trajectory of the center of mass and consequent conservation of the pendular mechanism. However, the role of the inverted pendulum mechanism that combines speed, load, and gradient during walking remains unknown. In the present study, 10 subjects walked on a treadmill, with and without loading (25% of the body mass), at different speeds and slopes (0%, +7%, and +15%). The three-dimensional motion and VO2 were simultaneously registered. The mechanical external and internal work and the cost of transport (C) changed with the speed and gradient, but the load only affected C. OPT decreased with increasing gradient, and the pendular mechanics (R) was modified mainly as a result of changes in speed and gradient. OPT and R were independent of the load in these gradients. Remarkably, R increased with increasing speed and decreased (to 30%) with an increasing gradient; moreover, R was independent of load. Therefore, the energy-saving strategy by the pendular mechanism persists, although at a diminished level, in loaded walking on gradients and partially explains the OPT in this condition.

A mechanical link model of two-toed sloths: no pendular mechanics during suspensory locomotion

Sloths are morphologically specialized in suspensory quadrupedal locomotion and posture. During steady-state locomotion they utilize a trot-like footfall sequence. Contrasting the growing amount of published accounts of the functional morphology and kinematics of sloth locomotion, no study concerned with the dynamics of their quadrupedal suspensory locomotion has been conducted. Brachiating primates have been shown to travel at low mechanical costs using pendular mechanics, but this is associated with considerable dynamic forces exerted onto the support. To test whether sloth locomotion can be described by simple connected pendulum mechanics, we analyzed the dynamics of sloth locomotion with use of a mechanical segment link model. The model integrates the body segment parameters and is driven by kinematic data with both segment parameters and kinematic data obtained from the same sloth individual. No simple pendular mechanics were present. We then used the model to carry out an inverse dynamic analysis. The analysis allowed us to estimate net limb joint torques and substrate reaction forces during the contact phases. Predominant flexing limb joint torque profiles in the shoulder, elbow, hip, and knee are in stark contrast to published dominant extensor torques in the limb joints of pronograde quadrupedal mammals. This dissimilarity likely reflects the inverse orientation of the sloth towards the gravity vector. Nevertheless, scapular pivot and shoulder seem to provide the strongest torque for progression as expected based on unchanged basic kinematic pattern previously described. Our model predicts that sloths actively reduce the dynamical forces and moments that are transmitted onto the support. We conclude that these findings reflect the need to reduce the risk of breaking supports because in this case sloths would likely be unable to react quickly enough to prevent potentially lethal falls. To achieve this, sloths seem to avoid the dynamical consequences of effective pendular mechanics.

Body size and the neural control of movement

Summary Nervous systems, muscles, and motor organs (biomechanics) generate movement cooperatively and should therefore change coordinately as body size changes. Proving this hypothesis requires a description of the nervous system, muscle, and biomechanics of individual species and comparison of these properties across a collection of species spanning a large size range. Obtaining these data in even one species is daunting, and we are far from reaching a general theory of how nervous system, muscle, and biomechanics depend on body size. Sufficient cross-species data nonetheless exist to identify some consequences of body size on the neural control of movement, which form the focus of this Primer: for example, locomotor cycle period depends on leg length; large animals should devote more neural resources to hazard avoidance and stride correction; the importance of gravity and momentum increases, and of passive muscle properties decreases, with limb size; and the medium in which movements occur affects these size dependencies. These considerations suggest that, in applying biological data to robotic design, proper ‘size' should be maintained across all levels (i.e., if small-animal neural mechanisms are used, so should small-animal muscle and biomechanical properties).

The reasons why stroke patients expend so much energy to walk slowly

BackgroundThe energy consumed per covered distance (C) is increased in hemiparetic stroke adults during walking. ObjectiveTo ascertain if increased C in stroke patients is a result of increased mechanical work, of decreased efficiency of work production by muscles or of slow walking speed. MethodsC and mechanical work were computed in 20 patients walking on a force measuring treadmill at speeds ranging from 1kmh−1 to their own maximum speed (WSMAX). Works done by healthy and pathological limbs were computed separately. ResultsFor hemiparetic patients, C was around 1.7 times greater than normal. When these patients had a slower WSMAX, they had greater C and mechanical work (r=−0.44 and −0.57, respectively). The increased C was related to the external work performed to lift the center of body mass when the healthy limb was supporting the body weight (r=0.77). ConclusionsThe increase of C in stroke patients is more pronounced when WSMAX is slow. Moreover, this increase is related to increased mechanical work done by muscles and is not related to slow walking speed or decreased efficiency. As in healthy subjects, C and external work presented optimum speeds, indicating a preserved pendular mechanism of walking.

Impact of ankle osteoarthritis on the energetics and mechanics of gait: The case of hemophilic arthropathy

BackgroundOsteoarthritis may affect joints in any part of the body, including the ankle. The purpose of this study was to assess the impact of ankle osteoarthritis on the energetics and mechanics of gait, while taking into account the effect of slower speed generally adopted by patients with osteoarthritis. MethodsUsing a motion analysis system, synchronous kinematic, kinetics, spatiotemporal, mechanics and metabolic gait parameters were measured in 10 patients diagnosed with ankle osteoarthritis consecutive to hemophilia. The subjects walked at a self-selected speed and their performance was compared to speed-matched normal values obtained in healthy control subjects. FindingsSpeed-normalization using a Z-score transformation showed a significant increase in metabolic cost (Z=1.78; P=0.006) and decrease in mechanical work (Z=−0.97; P=0.009). As a consequence, muscular efficiency also decreased (Z=−0.97; P=0.001). These changes were associated with a surprising efficacy of the pendular mechanism, i.e., an improved recovery index (Z=0.97; P=0.004). InterpretationOur findings suggest that patients with ankle osteoarthritis adopt a walking strategy which improves recovery through the pendular mechanism. This may be a compensatory mechanism in order to economize energy which would counterbalance the energy waste due to low muscle efficiency. These modifications are proportional to the impaired ankle function. Our data provides a quantitative baseline to better understand the dynamics of ankle osteoarthritis and determine the individual role that lower limb joints play in the multiple chronic joint affections.

Intraspecific scaling of chewing cycle duration in three species of domestic ungulates

In mammals, chewing cycle duration (CCD) increases with various measures of size, scaling with body mass(0.13-0.28) and jaw length(0.55). Proposed explanations for these scaling relationships include the allometry of body size, basal metabolic rate and tooth size, on the one hand, and pendular mechanics treating the jaw as a gravity-driven pendulum, on the other. Little is known, however, about the relationship between CCD and size within species. Recent research in dogs demonstrates altogether different scaling exponents and weaker correlations. This research suggests that breed-specific growth rates influence the maturation of the neural networks generating chewing rhythm, which may be altered because of changes in jaw mass during early postnatal growth. Here, we explored the intraspecific scaling of CCD within a sample of adult horses ranging from miniatures to draft breeds and an ontogenetic sample of goats and alpacas from infants to adults. In horses, CCD scales with body mass(0.19) and jaw length(0.57), although in neither case is the correlation significant. In the ontogenetic samples of goats and alpacas, CCD is significantly correlated with body mass, scaling as CCD∝body mass(0.37) in both species. In goats, but not alpacas, CCD is also significantly correlated with jaw length, scaling as jaw length(1.032). As in dogs, the scaling of CCD in horses may reflect the influence of selective breeding on growth trajectories of different breeds, resulting in reduced body and jaw size differences among infants, when CCD is established, compared with adults. However, the allometric scaling of tooth size in horses of different breeds may be a potential influence on the scaling of CCD. The scaling of CCD with body and jaw size in goats, and to a lesser extent in alpacas, also suggests that the development of peripheral masticatory structures such as the teeth and occlusal relations may play a role in changes in CCD during the earliest stages of postnatal ontogeny.

The up and down bobbing of human walking: a compromise between muscle work and efficiency

Human walking has a peculiar straight-legged style. Consequently, the body's centre of mass (CM) moves up and down with each step, which is noticeable in their up and down head bobbing while walking. This vertical CM movement enables humans to save energy via a pendulum-like mechanism but is probably a relatively recent locomotor innovation insofar as earliest bipeds may have walked flexed and flat. We investigated the mechanics, energetics, muscle efficiency and optimization of human walking by decreasing and increasing the vertical CM displacement (flat and bouncy walking) in comparison to normal walking at six speeds (1-6 km h(-1)). In both flat and bouncy walking, the pendular mechanism was reduced and the energy cost was increased. However, this increase was unexpectedly much sharper in flat walking where muscles provided normal mechanical work but with a decrease in muscle efficiency. In bouncy walking, muscles provided extra mechanical work in an efficient way. Our results showed that not only do humans bob up and down in normal walking to save energy via a pendulum-like mechanism but also to make their muscles work efficiently. Actually, walking flat makes the muscles work in unfavourable conditions that waste energy. Furthermore, we are still close to a flat CM displacement relative to our current ability to change this displacement, which suggests that reducing vertical CM displacement is indeed important but only to certain limits. Evolution may ultimately have chosen the best compromise between flat locomotion that requires little work to move and bouncy locomotion that improves muscle efficiency to minimize energy consumption.

A pendular mechanism for maintenance of the immune memory

A possible mechanism for maintaining immune memory, based on idiotypic–anti-idiotypic interactions, is described. It is proposed that pendular dynamic swings in the levels of idiotypic antibodies (Ab1) and anti-idiotypic Ab2 may underlay immune memory. In the terms of the advanced concept, Ab dynamics in the maternal body might also play a significant role in education of the neonatal immune system.