Organismic Constraints Research Articles

Intentions, Perceptions and Actions Constrain Functional Intra- and Inter-Individual Variability in the Acquisition of Expertise in Individual Sports

Expertise in sport results from the adaptation of behavoirbehavoir to interacting constraints, individually per-ceived and encountered. With this emphasis on intentionality, perception and action to constrain behavoirbehavoir, the role of movement pattern stability, functional intra-individual and inter-individual performance variability is paramount. Here we illustrate these ideas with reference to two individual performance environments: ice climbing and breaststroke swimming. In ice climbing, compared to beginners, expert climbers exhibited greater levels of variability in upper- and lower-limb coordination patterns, exploring a larger range of limb positions and movement types (ice tool swinging, ice hole hooking). Ice fall properties contain affordances that induced variable motor coordination patterns in expert climbers, whereas learners used a basic and functionally stable motor organization to achieve their main goal of maintaining body equilibrium with respect to gravity. In swimming, while learners organized their limbs to advance in the water, their main intention was to balance, float, breathe, and perceive information. For these reasons they typically adopted one stable (in-phase) mode of arm-leg coordination whatever the swim speed. In contrast, experts harnessed available environmental and organismic constraints (strength, flexibility relative to aquatic resistance and the Archimedes principle) to satisfy a key performance constraint (swim fast). To achieve this aim, they varied the arm-leg coordination mode within a stroke cycle and swim speed. Together these data illustrate how functional performance in sport is predicated on the intertwined rela-tionship between intentions, actions and perceptions of each individual, requiring a blend of stable and variable movement patterns to satisfy changing task constraints.

Individual profiles of spatio-temporal coordination in high intensity swimming

The aim of the present study was to examine the inter-subject variability in inter-arm coordination during front crawl swimming at high intensity. Ten male competitive swimmers swam 200m front crawl at race pace. Two above water and four underwater cameras videotaped the test and APAS was used to assess the 3D anatomical points position and to calculate, afterwards, the angular position, velocity and the continuous relative phase, which was used to analyze upper limbs coupling during two arm stroke cycles for each 50m lap of the 200m front crawl event. The kinematics of the two arm stroke cycles was filtered and normalized to the total cycle duration. A significant decrease, caused by fatigue, was observed in the biomechanical and coordinative (temporal) parameters. The topography of the mean continuous relative phase curve showed a higher inter-subject variability between two groups (63.1° vs. 76.0°; p<.05), suggesting that several profiles of inter-limb coordination exist. Two clusters arose from the coordination profiling, which mainly stemmed from organismic constraints (i.e., the swimmer’s technique).

Energy density and its variation in space limit species richness of boreal forest birds

AbstractAim An area’s ability to support species may be dependent not only on the total amount of available energy it contains but also on energy density (i.e. available energy per unit area). Acknowledging these two aspects of energy availability may increase mechanistic understanding of how increased energy availability results in increased species richness. We studied the relationship between energy density, its variation in space and boreal forest bird species richness and investigated two possible mechanisms: (1) metabolic constraints of organisms, and (2) increased resource availability for specialists.Location Protected areas in Finland’s boreal forest.Methods We tested whether bird species richness was best determined by total energy availability in an area or by energy density and its variation within the area, before and after including bird abundance in the models. We evaluated two main explanatory variables: tree growth reflecting the rate of energy production and tree volume as a measure of biomass. In addition, we modelled individual species’ responses to energy density and its variation, and evaluated the prediction of the metabolic constraints hypothesis that small species are limited by energy density whereas large species are limited by total energy availability in the area.Results Energy density and its variation were good predictors of species richness: together with abundance they explained 84% of variation in species richness (compared with 74% for abundance alone). Pure metabolic constraints were unlikely to explain this relationship. Instead, the mechanism probably involved increased habitat heterogeneity benefiting specialist species. Total energy availability was also an important factor determining species richness but its effect was indirect via abundance.Main conclusions Our results corroborate the importance of energy availability as a driver of species richness in forest bird communities, and they indicate that energy density and its variation in the landscape strongly influence species richness even after accounting for abundance.

Longitudinal study of unimanual actions and grasping forces during infancy

Learning to grasp an object is an important milestone in neurological development during infancy. Several studies report development of reaching in infants but less attention is devoted to reaching with successful grasping and to development of grip force. This study investigates, in the first weeks of life, the development of palmar grasp both for assessment of unimanual/bimanual grasping actions in centrally and laterally placed objects and for measurement of exerted power grip force. We longitudinally examined ten infants from 18 weeks to 41 weeks, at 2-weeks intervals, with a toy placed in three positions (body midline, ipsilateral and contralateral shoulder). Our main aim was to study this development through an ecological approach. This was possible thanks to the use of the “biomechatronic gym”, a new platform purposively developed for measuring reaching and grasping forces. These longitudinal trials showed a good level of acceptance and involvement by infants of the entire system. The results demonstrated a significant increase in unimanual power grip force between the 18th and 30th week followed by a flat period until the 41st week; we also ascertained an early tendency to play bimanually with centrally and laterally placed objects with a subsequent increase in all ages of unimanual successful power grasping both for central task and midline crossing. These developmental changes may be, in part, related to organism constraints such as maturation of the corticospinal tract.

Evolutionary and organismic constraints on the relationship between spacer length and environmental conditions in clonal plants

The rate of lateral spread of clonal plants is considered a plastic trait that responds directly to environmental conditions. However, this response is likely constrained by evolutionary history and other species attributes. Here we ask how the relationships between lateral spread and the distribution of herbaceous plant species in different environments are influenced by the type of spacer (epigeogenous versus hypogeogenous rhizome), its persistence (integrator versus splitter), and the height and phylogeny of the plant. Analysis of spacer length of 367 species from temperate to arctic Europe revealed that other plant characteristics modulate the relationship between spacer length and environmental conditions. While plants with epigeogenous rhizomes, which have usually shorter spacers than hypogeogenous rhizomes, were associated with illuminated habitats, plants with hypogeogenous rhizomes were associated with warm habitats. These relationships were also shown within the specific rhizome type, as within the group of species with epigeogenous rhizomes, those having short spacers were associated with more light. The trend toward long spacers in warm environment was detected within both epigeogenous and hypogeogenous rhizome bearing species. Splitters were found to be associated with wet, nutrient rich habitats irrespective of rhizome type. When plant height was accounted for by using the ratio of spacer length to plant height (L:H) instead of absolute spacer length, no relationship with environmental variables was found until phylogenetic relationships among the species were taken into account. This implies that overall variability in L:H ratio in the dataset masked trends common for different taxonomic groups. Future comparative studies relating particular clonal growth forms or individual traits to environmental conditions should consider the constraints arising from other growth characteristics and evolutionary history of the subject species.

Age effects on the inter-joint coordination during obstacle-crossing

Seventeen healthy elderly and 17 young adults walked and crossed obstacles of different heights, while sagittal angles ( x) and angular velocities ( x′) of each joint were measured and their phase angles ( ϕ) calculated as tan −1( x′/ x). Relative phase angles (RPA) were also obtained, i.e., ϕ hip−knee and ϕ knee−ankle. The standard deviations of the RPA curve points were averaged to obtain deviation phase (DP) values for the stance and swing phase for each obstacle height. Both groups had similar RPA patterns, for both the leading and the trailing limb. The elderly were found to cross obstacles with increased leading toe-clearance, but unaltered inter-joint coordination patterns. During the leading limb crossing, greater variability of the inter-joint coordination, correlated to the increased toe-clearance, indicates that aging increases the variability of the way the lower limb joints are controlled during obstacle-crossing. The elderly did not change the pattern and variability of the inter-joint coordination during the trailing limb crossing, possibly because it is relatively easy for the elderly to meet the mechanical demands despite increased age-related organismic constraints. The normal baseline inter-joint coordination data in the healthy aging population will be useful for future identification of coordination impairments and evaluation of subsequent treatment in those patients with diseases who may have an increased risk of falling.

The Influence of Task Constraints on the Glenohumeral Horizontal Abduction Angle of the Overarm Throw of Novice Throwers

The action of the throwing arm during the development of the mature overarm throwing pattern has garnered much attention in recent years. Many of these studies have incorporated Newell’s (1986) developmental model into the description of the organismic (e.g., Halverson, Roberton, & Langendorfer, 1982; Langendorfer & Roberton, 2002) and/or environmental constraints placed upon the thrower (e.g., Thomas & French, 1985; Thomas, Michael, & Gallagher, 1994). According to Newell, three types of constraints—the organism, environment, and task—must be considered when investigating factors related to motor development and learning. These factors and their interactions are included in Newell’s triangular model as key sources of constraint when examining motor development at any age. Constraints are usually defined as facilitative channeling of movement, or limitations thereof, implying that constraints either encourage or limit motor development depending on the characteristics of the constraints (Haywood & Getchell, 2005). Organismic constraints involve the genetic makeup and an individual’s unique characteristics, such as height, limb length and mass, attentional focus, motivation, and arousal level. Because of organismic constraints, people performing the same task in identical environments may achieve various degrees of success (Haywood & Getchell, 2005). Environmental constraints include those that describe the setting in which an organism lives and thrives. For example, light, temperature, humidity level, air quality, nutritional opportunities, laws, cultural beliefs and practices, and normative views regarding acceptable behavior represent environmental constraints (Haywood & Getchell). Task constraints are controls that are placed upon the execution of the skill, such as skill criteria, equipment used, and the task itself (Haywood & Getchell). Only a few studies have accounted for the third axiom of Newell’s model, which is the task constraint (Cross, 2004; Southard, 1998). For instance, several studies have investigated how various populations of children respond to different instructional strategies when learning the skill of throwing (e.g., Goodway & Branta, 2003; Goodway, Rudisill, & Valentini, 2002; Valentini & Rudisill, 2004a, 2004b), but the majority of the studies have not reported or described the size or weight of the throwing implement. The failure to report and/or standardize task constraints, such as ball size and weight, makes comparisons across studies difficult, due to evidence that the size and weight of the ball influence the mechanics of overarm throwing (Alexander, 1991; Cross; 2004). Therefore, this study aimed to determine the influence of task constraints on the horizontal abduction angle of the overarm throw of novice throwers. Specifically, the study attempted to determine whether increasing the inertial components of the distal portion of the throwing arm forces the arm into an increased glenohumeral horizontal abduction angle. In an attempt to define the effects of task constraints on the overarm throwing motion, Alexander suggested The Influence of Task Constraints on the Glenohumeral Horizontal Abduction Angle of the Overarm Throw of Novice Throwers

Mechanistic niche modelling: combining physiological and spatial data to predict species’ ranges

Species distribution models (SDMs) use spatial environmental data to make inferences on species' range limits and habitat suitability. Conceptually, these models aim to determine and map components of a species' ecological niche through space and time, and they have become important tools in pure and applied ecology and evolutionary biology. Most approaches are correlative in that they statistically link spatial data to species distribution records. An alternative strategy is to explicitly incorporate the mechanistic links between the functional traits of organisms and their environments into SDMs. Here, we review how the principles of biophysical ecology can be used to link spatial data to the physiological responses and constraints of organisms. This provides a mechanistic view of the fundamental niche which can then be mapped to the landscape to infer range constraints. We show how physiologically based SDMs can be developed for different organisms in different environmental contexts. Mechanistic SDMs have different strengths and weaknesses to correlative approaches, and there are many exciting and unexplored prospects for integrating the two approaches. As physiological knowledge becomes better integrated into SDMs, we will make more robust predictions of range shifts in novel or non-equilibrium contexts such as invasions, translocations, climate change and evolutionary shifts.

Unimodal experience constrains while multisensory experiences enrich cognitive construction

AbstractMareschal and his colleagues argue that cognition consists of partial representations emerging from organismic constraints placed on information processing through development. However, any notion of constraints must consider multiple sensory modalities, and their gradual integration across development. Multisensory integration constitutes one important way in which developmental constraints may lead to enriched representations that serve more than immediate behavioural goals.

The Ontological Roots of Human Science: the Message of Evolution—The Physics of Freedom (Choice)

The original proposal of H. H. Pattee (1971) of basing quantum theoretical measurement theory on the theory of the origin of life, and its far reaching consequences, is discussed in the light of a recently emerging biological paradigm of internal measurement. It is established that the “measurement problem” of quantum physics can, in principle, be traced back to the internal material constraints of the biological organisms, where choice is a fundamental attribute of the self-measurement of matter. In this light, which is shown to be a consequence of Pattee's original suggestion, it is proposed that biological evolution is a gradual liberation from the inert unity of “subject” and “object” of inanimate matter (as “natural law” and “initial conditions”), to a split biological existence of them and, as a consequence, the “message of evolution” is freedom, rather than complexity in itself. Some classical philosophical systems are brought into context to show that the epistemologies of several strictly philosophical systems of the social sciences are well acquainted with the problem and their solutions support our conclusions.

Toy-oriented changes in early arm movements III: Constraints on joint kinematics

The purpose of this study was to identify invariant features of shoulder and elbow kinematics during prereaching arm movements with and without a toy present. Invariant movement features may reflect the presence of constraints that reduce the complexity of learning to reach and provide a link between early arm movements and reaching. Joint excursion and smoothness were consistently greater at the shoulder than the elbow suggesting strong organismal constraints on prereaching movements. Speed became greater in the shoulder than the elbow only with a toy present during the 4 weeks leading up to reach onset suggesting the introduction of task related constraints. We propose that organismal constraints on joint coordination throughout the prereaching period provide a foundation for the overlay of task related constraints closer to reach onset. We also suggest that the coordinative structures of early arm movements and later reaching may be much more similar than currently thought. This similarity would significantly reduce the elements needing to be actively controlled, and simplify the learning process.

Swimming constraints and arm coordination

Following Newell’s concept of constraint (1986), we sought to identify the constraints (organismic, environmental and task) on front crawl performance, focusing on arm coordination adaptations over increasing race paces. Forty-two swimmers (15 elite men, 15 mid-level men and 12 elite women) performed seven self-paced swim trials (race paces: as if competitively swimming 1500m, 800m, 400m, 200m, 100m, 50m, and maximal velocity, respectively) using the front crawl stroke. The paces were race simulations over 25m to avoid fatigue effects. Swim velocity, stroke rate, stroke length, and various arm stroke phases were calculated from video analysis. Arm coordination was quantified in terms of an index of coordination (IdC) based on the lag time between the propulsive phases of each arm. This measure quantified three possible coordination modes in the front crawl: opposition (continuity between the two arm propulsions), catch-up (a time gap between the two arm propulsions) and superposition (an overlap of the two arm propulsions). With increasing race paces, swim velocity, stroke rate, and stroke length, the three groups showed a similar transition in arm coordination mode at the critical 200m pace, which separated the long- and mid-pace pattern from the sprint pace pattern. The 200m pace was also characterized by a stroke rate close to 40strokemin−1. The finding that all three groups showed a similar adaptation of arm coordination suggested that race paces, swim velocity, stroke rate and stroke length reflect task constraints that can be manipulated as control parameters, with race paces (R2=.28) and stroke rate (R2=.36) being the best predictors of IdC changes. On the other hand, only the elite men reached a velocity greater than 1.8ms−1 and a stroke rate of 50strokemin−1. They did so using superposition of the propulsion phases of the two arms, which occurred because of the great forward resistance created when these swimmers achieved high velocity, i.e., an environmental constraint. Conversely, the elite women and mid-level men had shorter stroke lengths and maintained a time gap between the propulsions of the two arms throughout the increase in paces, with gender and expertise explaining 9% and 8.3% of the IdC changes, respectively. These results indicate that arm coordination cannot be interpreted solely from the IdC value but should be considered from the perspective of task, environmental, and organismic constraints. These constraints can serve as control parameters in experiments aimed at gaining insight into changes in arm coordination during the front crawl. In this context, catch-up coordination, which is often considered as a mistake, was seen to be an adaptation to a relative constraint.

Biomechanical models, motor control theory, and development

The role of biomechanics can be critical in understanding the development of control and coordination only when theory recognizes the role that physical constraints of the environment and tasks in helping shape movement patterns and their development. A systems-theoretic approach and biomechanical model are briefly outlined that capture the interplay of organism, environment and task constraints. When such a model and theory are employed, the tools of biomechanics can play a much greater role than a simple description of changes in development. They can be used to show how control and coordination develop according to biomechanical laws and optimality criteria. Copyright © 2005 John Wiley & Sons, Ltd.

The Hexokinase of the Hyperthermophile Thermoproteus tenax: ATP-DEPENDENT HEXOKINASES AND ADP-DEPENDENT GLUCOKINASES, TWO ALTERNATIVES FOR GLUCOSE PHOSPHORYLATION IN ARCHAEA

The phosphorylation of glucose by different sugar kinases plays an essential role in Archaea because of the absence of a phosphoenolpyruvate-dependent transferase system characteristic for Bacteria. In the genome of the hyperthermophilic Archaeon Thermoproteus tenax a gene was identified with sequence similarity to glucokinases of the so-called ROK family (repressor protein, open reading frame, sugar kinase). The T. tenax enzyme, like the recently described ATP-dependent "glucokinase" from Aeropyrum pernix, shows the typical broad substrate specificity of hexokinases catalyzing not only phosphorylation of glucose but also of other hexoses such as fructose, mannose, or 2-deoxyglucose, and thus both enzymes represent true hexokinases. The T. tenax hexokinase shows strikingly low if at all any regulatory properties and thus fulfills no important control function at the beginning of the variant of the Embden-Meyerhof-Parnas pathway in T. tenax. Transcript analyses reveal that the hxk gene of T. tenax is cotranscribed with an upstream located orfX, which codes for an 11-kDa protein of unknown function. Growth-dependent studies and promoter analyses suggest that post-transcriptional RNA processing might be involved in the generation of the monocistronic hxk message, which is observed only under heterotrophic growth conditions. Data base searches revealed T. tenax hexokinase homologs in some archaeal, few eukaryal, and many bacterial genomes. Phylogenetic analyses confirm that the archaeal hexokinase is a member of the so-called ROK family, which, however, should be referred to as ROK group because it represents a group within the bacterial glucokinase fructokinase subfamily II of the hexokinase family. Thus, archaeal hexokinases represent a second major group of glucose-phosphorylating enzymes in Archaea beside the recently described archaeal ADP-dependent glucokinases, which were recognized as members of the ribokinase family. The distribution of the two types of sugar kinases, differing in their cosubstrate as well as substrate specificity, within Archaea is discussed on the basis of physiological constraints of the respective organisms.

Biological Hierarchies, Their Birth, Death and Evolution by Natural Selection

Description of the biologicalhierarchy of the organism has been extendedhere to included the evolutionary andecological sub-hierarchies with theirrespective levels in order to give a completehierarchical description of life. These newdescriptions include direction of formation,types of constraints, and dual levels. Constraints are produced at the macromolecularlevel of genes/proteins, some of which (a) aredescendent restraints which hold a hierarchytogether and others (b) interact horizontallywith selective agents at corresponding levelsof the niche. The organism is a dual levelconstrained by both the ecologicalsub-hierarchy (survival) and evolutionarysub-hierarchy (fitness) while serving as thehighest level of the specializationsub-hierarchy, therefore, it is unique inbelonging to three sub-hierarchies. Organismsexperience birth, sometimes death, andparticipate in evolution. Birth of an organismis realized when a cell is removed from theconstraints of the organism and assumes itsown organismal constraints. Death occurs withthe cessation of protein synthesis becauseproteins and their products constitutecomponents at high levels of the hierarchy. Selection is of two types, natural selection,involving adaptive traits interacting withfeatures in a niche, and hierarchicalselection, requiring traits to be compatiblewith existing hierarchical constraints.

The relation of unimanual and bimanual reaching to crossing the midline.

The present study assessed the development of reaching for objects positioned in front of the contralateral shoulder. In particular, it examined how the development of crossing the midline is related to the development of bimanual reaching. Twenty infants were observed longitudinally at 12, 18, and 26 weeks of age while reaching for two balls (3 cm and 8 cm in diameter) located at three positions (ispsilateral, midline, and contralateral). The reaches were analyzed from video recordings. With age, the infants increasingly adapted the number of hands used to the size of the object. The number of reaches crossing the body midline increased with age. Furthermore, the majority of the midline crossings were part of two-handed reaches for the large ball and occurred at or after onset of bimanual reaching. Together, these findings strongly suggest that the development of crossing the body midline emerges in the context of bimanual reaching. It was concluded that the need to grasp a large ball positioned contralaterally with two hands induces midline crossing. Hence, the development of midline crossings is not exclusively dependent on organismic constraints (e.g., the maturation of hemispheric connections), but rather on their interaction with environmental constraints (e.g., object size).

Conjugal type IV macromolecular transfer systems of Gram-negative bacteria: organismal distribution, structural constraints and evolutionary conclusions.

Conjugal type IV macromolecular transfer systems of Gram-negative bacteria: organismal distribution, structural constraints and evolutionary conclusions.

Metabolic energy expenditure and the regulation of movement economy

Over the years, various psychological theories have embraced notions ofeconomy, efficiency, orleast effort to explain how complex movement sequences are organized and modified. The purpose of the present paper was to synthesize various perspectives on this issue, to identify a common hypothesis, and to propose a conceptual framework that explains how movement economy is regulated. The framework presented here postulates that adaptive movement patterns emerge as a function of the organism’s propensity to minimize metabolic energy expenditure with respect to task, environment, and organism constraints to action. An important role is also proposed for interoceptive sensory information in guiding motor skill learning and control. The paper concludes by suggesting future directions in four areas of movement economy research that contribute to understanding the learning and control of movement in both human and nonhuman organisms.

Multilimb coordination patterns in simultaneous, dissimilar upper and lower limb tasks

Multilimb coordination was examined when subjects clapped (in-phase pattern) while walking (out-of-phase pattern) or galloping (off-phase pattern). Based on previous studies of rhythmic limb movements it was predicted that in-phase frequency-locked coordination would be the most attractive mode, although a previous study by Muzii et al. (1984) had suggested that other coordination modes existed. Subjects clapped and walked or galloped at a preferred speed and at one of four different task manipulations: extended practice, overall speed, temporal and spatial. The resultant multilimb coordination patterns were classified in terms of frequency-locking, phase relationships and stability of between-girdle and within-girdle relationships. Absolute step frequency-locking was the most attractive coordination mode for the clap/walk task, but an unlocked-stable coordination mode was also present. For the clap/gallop, absolute stride frequency-locking was the only attractive coordination mode. Subjects tended to be stable in their preferences across trials and across changes in speed or they adopted a frequency-locked mode. Temporal and spatial manipulations of one limb girdle with respect to the other most commonly resulted in an unlocking of frequency, although there was much inter-subject variability and signs of individual attentional strategies. In general, the results indicated that coordination was a product of a complex interaction of organismic and task constraints, but with many characteristics that are consistent with a general dynamical systems perspective on rhythmic interlimb coordination.

Achieving Coordination in Prehension: Joint Freezing and Postural Contributions.

The focus of the present study was on the intersegmental relationships that emerge when both task and oganismic constraints are imposed upon the coordination system. Seven right-handed subjects were required to reach and grasp a cup (hand transport phase) and place it on a designated target (cup transport phase), using either their preferred or nonpreferred hand. The kinematics of the movement were examined as a function of task (grasping a full cup versus grasping an empty one) and organismic (preferred or nonpreferred hand) constraints. During the hand transport phase, a task constraint effect was revealed through an increase in the low-velocity phase for the full cup condition. This constraint coexisted with a decrease in angular motion of the shoulder and elbow joints, indicating subjects reduced the number of variables to be independently controlled in the final homing-in stage of the movement. Accompanying this decrease in angular change was an increase in the displacement of the trunk. During the cup transport phase, the trunk was shown to contribute significantly more to the movement in the full cup condition and for the left hand movements, thereby increasing the stability of the movement system. These findings are in agreement with Bernstein's (1967) notion of fixating parts of the body as an initial solution to a movement problem, and they lend support to the concept of a proximodistal organization of coordination.