An official website of the United States government
The scale-dependence of locomotor performance has long been studied in comparative biomechanics, but how animals move in their natural environment remains poorly understood. At the upper extreme of body mass, baleen whales (Mysteci) are predictably among the most efficient swimmers in terms of cost of transport through a combination of low mass-specific metabolic rate and high hydrodynamic efficiency. Such efficiency enables these oceanic giants to migrate vast distances and thus underlies a major component of their life history and functional ecology. However, we lack even basic kinematic data for most species. Here we combine morphometric data from flyover drone photography, whale-borne inertial sensing tag data, and computational fluid dynamics (CFD) to study the locomotion of four rorqual species. Focusing on fundamental kinematic parameters such as tailbeat frequency and forward speed, we quantified spatial and temporal changes in swimming performance for individual whales and compared these metrics across a wide body mass range. We also calculated thrust and drag using lunate tail hydrodynamic modeling (Fish 1993), and compared these values against those from CFD simulations carried out with realistic rigid-body models. Differences in excess of 100% between the two approaches point to the significant contributions of tail and head heaving to overall drag, and thus the need to account for them in rigid-body CFD simulations. Together these kinematic data and CFD modeling inform a new parametric factor designed at multiplying the rigid-body drag equation to predict the contribution of body heaving unsteady hydrodynamics in cetaceans.
more »
« less
Mediterranean Spur-Thighed Tortoises (Testudo graeca) Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill
Tortoises are famed for their slow locomotion, which is in part related to their herbivorous diet and the constraints imposed by their protective shells. For most animals, the metabolic cost of transport (CoT) is close to the value predicted for their body mass. Testudines appear to be an exception to this rule, as previous studies indicate that, for their body mass, they are economical walkers. The metabolic efficiency of their terrestrial locomotion is explainable by their walking gait biomechanics and the specialisation of their limb muscle physiology, which embodies a predominance of energy-efficient slow-twitch type I muscle fibres. However, there are only two published experimental reports of the energetics of locomotion in tortoises, and these data show high variability. Here, Mediterranean spur-thighed tortoises (Testudo graeca) were trained to walk on a treadmill. Open-flow respirometry and high-speed filming were simultaneously used to measure the metabolic cost of transport and to quantify limb kinematics, respectively. Our data support the low cost of transport previously reported and demonstrate a novel curvilinear relationship to speed in Testudines, suggesting tortoises have an energetically optimal speed range over which they can move in order to minimise the metabolic cost of transport.
more »
« less
- Award ID(s):
- 1755187
- PAR ID:
- 10415485
- Date Published:
- Journal Name:
- Biology
- Volume:
- 11
- Issue:
- 7
- ISSN:
- 2079-7737
- Page Range / eLocation ID:
- 1052
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Herein, the dataset generated for Queeno et al. [1] is presented and described. Mammalian skeletal muscle slow (MyHC-I) fiber composition data was collated from 269 eligible studies identified via a systematic literature search and meta-analysis, following a structure similar to PRISMA [2]. Academic search systems were queried with terms relating to mammalian skeletal muscle fiber content and reference lists of selected articles were thoroughly investigated for additional studies. Eligible studies were those that provided skeletal muscle fiber composition data from mammalian species that were not subjected to experimental manipulations. Taxonomic information, sex, age, number of individuals sampled, average body mass (kg), average slow fiber content (%) of each skeletal muscle under investigation and fiber-typing methodology were collated from eligible studies when available. Muscle fiber composition data was collected from more than 200 skeletal muscles across 174 mammalian species, which will be of value to those interested in muscle physiology, interspecific muscle comparisons, and connections between muscle physiology, taxonomy, body mass, ecomorphology and locomotor strategy (among others).more » « less
-
null (Ed.)Abstract The domestic dog is interesting to investigate because of the wide range of body size, body mass, and physique in the many breeds. In the last several years, the number of clinical and biomechanical studies on dog locomotion has increased. However, the relationship between body structure and joint load during locomotion, as well as between joint load and degenerative diseases of the locomotor system (e.g. dysplasia), are not sufficiently understood. Collecting this data through in vivo measurements/records of joint forces and loads on deep/small muscles is complex, invasive, and sometimes unethical. The use of detailed musculoskeletal models may help fill the knowledge gap. We describe here the methods we used to create a detailed musculoskeletal model with 84 degrees of freedom and 134 muscles. Our model has three key-features: three-dimensionality, scalability, and modularity. We tested the validity of the model by identifying forelimb muscle synergies of a walking Beagle. We used inverse dynamics and static optimization to estimate muscle activations based on experimental data. We identified three muscle synergy groups by using hierarchical clustering. The activation patterns predicted from the model exhibit good agreement with experimental data for most of the forelimb muscles. We expect that our model will speed up the analysis of how body size, physique, agility, and disease influence neuronal control and joint loading in dog locomotion.more » « less
-
Abstract The force-generating capacity of muscle depends upon many factors including the actin-myosin filament overlap due to the relative length of the sarcomere. Consequently, the force output of a muscle may vary throughout its range of motion, and the body posture allowing maximum force generation may differ even in otherwise similar species. We hypothesized that corn snakes would show an ontogenetic shift in sarcomere length range from being centered on the plateau of the length-tension curve in small individuals to being on the descending limb in adults. Sarcomere lengths across the plateau would be advantageous for locomotion, while the descending limb would be advantageous for constriction due to the increase in force as the coil tightens around the prey. To test this hypothesis, we collected sarcomere lengths from freshly euthanized corn snakes, preserving segments in straight and maximally curved postures, and quantifying sarcomere length via light microscopy. We dissected 7 muscles (spinalis, semispinalis, multifidus, longissimus dorsi, iliocostalis (dorsal and ventral), and levator costae) in an ontogenetic series of corn snakes (mass = 80–335 g) at multiple regions along the body (anterior, middle, and posterior). Our data shows all of the muscles analyzed are on the descending limb of the length-tension curve at rest across all masses, regions, and muscles analyzed, with muscles shortening onto or past the plateau when flexed. While these results are consistent with being advantageous for constriction at all sizes, there could also be unknown benefits of this sarcomere arrangement for locomotion or striking.more » « less
-
Skeletal muscle slow fiber (MyHC-I) content varies across muscles and taxa and is one of the traits that distinguishes humans from other apes, yet no study to date has compiled this interspecific data into a single, usable format. Thus, the goal of this study was to collate mammalian skeletal muscle slow fiber composition data from published, peer-reviewed articles into a single, open-access Excel sheet for interspecific comparison and analysis (as in Queeno et al., 2023). A systematic literature search and review was conducted between June 1 2021 and November 30 2022 following a structure similar to PRISMA. Terms relating to mammalian skeletal muscle fiber composition were queried using academic search systems (e.g. Google Scholar) and library databases for relevant primary articles. Reference lists in relevant articles were thoroughly investigated for eligible studies. In total, 269 primary articles were deemed eligible for inclusion in the meta-analysis (i.e. these studies provided skeletal muscle fiber composition data from mammalian species that were not subjected to experimental manipulations). Relevant metadata (e.g. taxonomic information, sex, age, fiber-typing methodology, average body mass, and average percent slow fiber content) was then extracted from the text, figures, tables, and supplementary materials of eligible studies when available. Muscle fiber composition data was collected from more than 200 skeletal muscles across 174 mammalian species, which will be of immense value to those interested in muscle physiology, interspecific muscle comparisons, and connections between muscle physiology, taxonomy, body mass, ecomorphology and locomotor strategy (among others). These data highlight certain species, taxonomic orders, and muscles for which fiber composition data is lacking and needs investigation. Hopefully, these data will spark interest in gathering muscle fiber composition data from underrepresented species and muscles, and generate interest in pursuing questions relating to muscle physiology and evolution, as well as analyses based on interspecific datasets.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/biology11071052
