Locomotion as a Powerful Model to Study Integrative Physiology: Efficiency, Economy, and Power Relationship

Locomotion is the most common form of movement in nature. Its study allows analysis of interactions between muscle functions (motor) and lever system arrangements (transmission), thereby facilitating performance analysis of various body organs and systems. Thus, it is a powerful model to study various aspects of integrative physiology. The results of this model can be applied in understanding body functions and design principles as performance outputs of interest for medical and biological sciences. The overall efficiency (effoverall) during locomotion is an example of an integrative parameter, which results from the ratio between mechanical output and metabolic input. Although the concepts of cost (i.e., metabolic expenditure relative to distance) and power (i.e., metabolic expenditure relative to time) are included in its calculation, the effoverall establishes peculiar relations with these variables. For a better approach to these aspects, in this study, we presented the physical-mathematical formulation of efficiency, as well as its conceptual definitions and applications. Furthermore, the concepts of efficiency, cost, and power are discussed from the biological and medical perspectives. Terrestrial locomotion is a powerful model to study integrative physiology in humans, because by analyzing the mechanical and metabolic determinants, we may verify the efficiency and economy relationship through locomotion type, and its characteristics and restrictions. Thus, it is possible to elaborate further on various improved intervention strategies, such as physical training, competition strategies, and ergogenic supplementation

Physiologic and Kinematical Effects of Water Run Training on Running Performance

The purpose of this study was to analyze whether trained competitive runners could maintain running kinematics, cardiorespiratory performance (VO2peak, ventilatory threshold, running economy) and on-land running performance by replacing 30% of conventional training with water run training during 8 weeks. Eighteen runners were divided in two groups: on-land run (OLR Group) and deep water run (DWR Group). The DWR Group replaced 30% of training volume on land with DWR and the OLR group trained only on land (both groups undertaken workouts 6-7 d.wk-1 for a total of 52 sessions). No significant intra- or intergroup differences were observed for VO2peak in the DWR Group and OLR Group. Similarly, ventilatory threshold second was unaltered in the DWR Group and OLR Group. Regarding running economy (at 14 km.h-1) also, no intra- or intergroup differences were found in the DWR Group (pre = 43.4 ± 5.0, post = 42.6 ± 3.85 ml.kg-1.min-1) and OLR Group (pre = 43.9 ± 2.5, post = 42.6 ± 2.6 ml.kg-1.min-1). Kinematic responses were similar within and between groups. Water running may serve as an effective supplementary training over a period of 8 weeks up to 30% of land training volume for competitive runners

Mechanical and energetic determinants of impaired gait following stroke: segmental work and pendular energy transduction during treadmill walking

Systems biology postulates the balance between energy production and conservation in optimizing locomotion. Here, we analyzed how mechanical energy production and conservation influenced metabolic energy expenditure in stroke survivors during treadmill walking at different speeds. We used the body center of mass (BCoM) and segmental center of mass to calculate mechanical energy production: external and each segment’s mechanical work (Wseg). We also estimated energy conservation by applying the pendular transduction framework (i.e. energy transduction within the step; Rint). Energy conservation was likely optimized by the paretic lower-limb acting as a rigid shaft while the non-paretic limb pushed the BCoM forward at the slower walking speed. Wseg production was characterized by greater movements between the limbs and body, a compensatory strategy used mainly by the non-paretic limbs. Overall, Wseg production following a stroke was characterized by non-paretic upper-limb compensation, but also by an exaggerated lift of the paretic leg. This study also highlights how post-stroke subjects may perform a more economic gait while walking on a treadmill at preferred walking speeds. Complex neural adaptations optimize energy production and conservation at the systems level, and may fundament new insights onto post-stroke neurorehabilitation

KINEMATIC ANALYSIS OF MIDDLE-DISTANCE RUNNERS DURING TREADMILL RUNNING AND DEEP WATER RUNNING

The present study compared the kinematics of treadmill running (TR) with deep water running (DWR). Five male middle-distance runners of national level were requested to run in intensities of regenerative effort, long aerobic, 5/10 km, 400/800 m and 100/200 m on treadmill and water. Three complete running steps were recorded. Two-dimensional analysis methods were employed to analyse the lower limb movement and general kinematics. The results revealed diferences (

Deep water running: limits and possibilities for high performance

ABSTRACT The purpose of this study was to analyze the limits and possibilities of deep water running on training of performance runners. Besides, it has been discussed the submaximal acute, maximal acute and chronical responses, following physiological and biomechanical aspects between running on land and deep water running. Heart rate and oxygen uptake's maximal responses are lower in aquatic exercise than in running on land. Experimental evidences suggest the deep water running training for performance athletes, but these studies are limited in training program until ten weeks

Effect of weighted sled towing on sprinting effectiveness, power and force-velocity relationship

This study aimed to compare the components of force-velocity (F-V) and power-velocity (P- V) profiles and the mechanical effectiveness of force application (or force ratio–RF) among various sled-towing loads during the entire acceleration phase of a weighted sled sprint. Eighteen sprinters performed four 50-m sprints in various conditions: unloaded; with a load corresponding to 20% of the athlete’s body mass (BM); with a load of 30% BM; and with a load of 40% BM. Data were collected with five video cameras, and the images were digitised to obtain velocity from the derivation of the centre-of-mass position. F-V and P-V compo- nents and RF were estimated from sprinting velocity-time data for each load using a vali- dated method that is based on an inverse dynamic approach applied to the sprinter’s centre- of-mass (it models the horizontal antero-posterior and vertical ground reaction force compo- nents) and requires only measurement of anthropometric and spatiotemporal variables (body mass, stature and instantaneous position or velocity during the acceleration phase). The theoretical maximal velocity decreased with load compared with the unloaded condition (for 20% BM: -6%, effect size (ES) = 0,38; for 30% BM: -15%, ES = 1.02; for 40% BM: -18%, ES = 1.10). The theoretical maximal horizontal force (F0) and maximal power were not dif- ferent among conditions. However, power at the end of the acceleration phase increased with load (40% BM vs 0%: 72%; ES = 2.73) as well as the maximal mechanical effectiveness (12%; ES = 0.85). The linear decrease in RF was different between 30 or 40% BM and the unloaded condition (-23%; ES = 0.74 and 0.66). Better effectiveness may be developed with 40% BM load at the beginning of the acceleration and with the various load-induced changes in the components of the F-V and P-V relationships, allowing a more accurate determination of optimal loading conditions for maximizing power

Editorial: Structural and mechanistic determinants of endurance performance

[no abstract available

Determinants of age-related decline in walking speed in older women

Background Walking speed is reduced with aging. However, it is not certain whether the reduced walking speed is associated with physical and coordination fitness. This study explores the physical and coordination determinants of the walking speed decline in older women. Methods One-hundred-eighty-seven active older women (72.2 ± 6.8 years) were asked to perform a 10-m walk test (self-selected and maximal walking speed) and a battery of the Senior fitness test: lower body strength, lower body flexibility, agility/dynamic balance, and aerobic endurance. Two parameters characterized the walking performance: closeness to the modeled speed minimizing the energetic cost per unit distance (locomotor rehabilitation index, LRI), and the ratio of step length to step cadence (walk ratio, WR). For dependent variables (self-selected and maximal walking speeds), a recursive partitioning algorithm (classification and regression tree) was adopted, highlighting interactions across all the independent variables. Results Participants were aged from 60 to 88 years, and their self-selected and maximal speeds declined by 22% and 26% (p < 0.05), respectively. Similarly, all physical fitness variables worsened with aging (muscle strength: 33%; flexibility: 0 to −8 cm; balance: 22%; aerobic endurance: 12%; all p < 0.050). The predictors of maximal walking speed were only WR and balance. No meaningful predictions could be made using LRI and WR as dependent variables. Discussion The results suggest that at self-selected speed, the decrease in speed itself is sufficient to compensate for the age-related decline in the motor functions tested; by contrast, lowering the WR is required at maximal speed, presumably to prevent imbalance. Therefore, any excessive lowering of LRI and WR indicates loss of homeostasis of walking mechanics and invites diagnostic investigation

Objetividade e fidedignidade do sistema de digitalização manual para o movimento de corrida

É fundamental na análise técnica da pesquisa esportiva o conhecimento das diversas fontes de variabilidade, especialmente avaliando as diferenças intra e inter-avaliadores. A proposta deste estudo foi examinar a objetividade e fidedignidade do processo de digitalização manual em uma seqüência de imagens de corrida entre três avaliadores e entre três digitalizações de um avaliador, e analisar o efeito da filtragem dos dados sobre a variabilidade dos dados (desvio-padrão). Todos os testes de Correlação Intra-Classe apresentaram altos coeficientes de correlação. 0 processo de digitalização manual é objetivo e fidedigno no movimento de corrida.Un understanding ofthe different variation sources in experimental sport research is fundamental to technical analysis, especially when comparing the Intra- and inter-evaluator differences. The purpose of thís study was to examine the objectivity and reliability of manual digitisation process in the analysed sequence of running among three evaluators and among three digitisations of the same evaluator, and analyse the effect of smoothing about the variability (standard deviation). Ali Intra-Class Correlations showed high correlation s coefficient This demonstrate that the manual digitisation process is objective and reliable for running movement

INFLUENCE OF DEEP WATER RUN TRAINING SUPPLEMENT ON THE MAINTENANCE OF AEROBIC PERFORMANCE AND KINEMATICS OF MIDDLE-DISTANCE RUNNERS

The purpose of this study was to examine whether trained competitive runners could maintain on-land running performance and kinematics, using 8 wk of deep water run supplement training (30%) instead of just on-land training. Eight trained male runners (V02MAX: 53,3 ± 4.1 ml. Kg,1. min,1) were assigned to one of the two groups, on-land run just (R) or water run supplement (WR). Following 8 wk of workouts, no significant intragroup or intergroup differences were observed for treadmill V02MAX, running economy, horizontal velocity, stride length, stride rate, time of support, time of flight and segmental body positions. It was concluded that deep water running may serve as an effective training supplement to land-based running for the maintenance of aerobic performance and running kinematics for up 8 wk in trained middle-distance runners