Selective Breeding and Short-Term Access to a Running Wheel Alter Stride Characteristics in House Mice

Abstract

Postural and kinematic aspects of running may have evolved to support high runner (HR) mice to run approximately threefold farther than control mice. Mice from four replicate HR lines selectively bred for high levels of voluntary wheel running show many differences in locomotor behavior and morphology as compared with four nonselected control (C) lines. We hypothesized that HR mice would show stride alterations that have coadapted with locomotor behavior, morphology, and physiology. More specifically, we predicted that HR mice would have stride characteristics that differed from those of C mice in ways that parallel some of the adaptations seen in highly cursorial animals. For example, we predicted that limbs of HR mice would swing closer to the parasagittal plane, resulting in a two-dimensional measurement of narrowed stance width. We also expected that some differences between HR and C mice might be amplified by 6 d of wheel access, as is used to select breeders each generation. We used the DigiGait Imaging System (Mouse Specifics) to capture high-speed videos in ventral view as mice ran on a motorized treadmill across a range of speeds and then to automatically calculate several aspects of strides. Young adults of both sexes were tested both before and after 6 d of wheel access. Stride length, stride frequency, stance width, stance time, brake time, propel time, swing time, duty factor, and paw contact area were analyzed using a nested analysis of covariance, with body mass as a covariate. As expected, body mass and treadmill speed affected nearly every analyzed metric. Six days of wheel access also affected nearly every measure, indicating pervasive training effects, in both HR and C mice. As predicted, stance width was significantly narrower in HR than C mice. Paw contact area and duty factor were significantly greater in minimuscle individuals (subset of HR mice with 50%-reduced hind limb muscle mass) than in normal-muscled HR or C mice. We conclude that stride characteristics of house mice are adaptable in response to both selective breeding and changes in daily locomotor behavior (activity levels) that occur during as few as 6 d. These results have important implications for understanding the evolution and coadaptation of locomotor behavior and performance.

Evolution of hindlimb bone dimensions and muscle masses in house mice selectively bred for high voluntary wheel‐running behavior

“…A more comprehensive view of skeletal evolution in these unique lines of mice will require consideration of the forelimbs, the pectoral and pelvic girdles (e.g., see Schutz et al, ), the axial skeleton, and their functional associations with ligaments, tendons, and muscles. Beyond this, we will need biomechanical studies to measure kinematics and forces during wheel running, as well as studies that attempt to relate morphology to gait and stride differences (e.g., see Claghorn et al, ; Sparrow et al, ).…”

Genetic Basis of Aerobically Supported Voluntary Exercise: Results from a Selection Experiment with House Mice

“…Kel is a blood group antigen with KO phenotypes affiliated with weakness, gait and motor coordination, neurological development, and heart function (Zhu et al 2009(Zhu et al , 2014. Previous experiments have shown the HR and C mice to have differences in heart physiology (Kolb et al 2013a), gait and motor coordination (Claghorn et al 2017), and brain development (Kolb et al 2013b).…”

“…Although some of the associated phenotypes, such as obesity, may have some correlation to phenotypic differences between HR and C mice, such as difference in body fat (Swallow et al 2001;Vaanholt et al 2008;Hiramatsu and Garland 2018), this does not directly answer the question of how Sorl1 influences running behavior. Mouse knockouts in this gene have not shown changes in running gait (Rohe 2008), whereas differences in gait do exist between HR and C mice (Claghorn et al 2017). However, these treadmill tests do not address exercise motivation, which might be influenced by such a neurobiologically relevant gene.…”

“…The hippocampus has been linked to the regulation of speed during locomotor behavior in both mice and rats by theta (Li et al 2012;Fuhrmann et al 2015;Sheremet et al 2019), gamma (Chen et al 2011;Ahmed and Mehta 2012), and delta oscillations (Furtunato et al 2020). Notably, the difference in daily running distance between HR and control lines is attributable mainly to an increase in average (and maximum) running speed, rather than the duration of running, especially in females (e.g., see Garland et al 2011a;Claghorn et al 2016Claghorn et al , 2017Copes et al 2018;Hiramatsu and Garland 2018). Another consideration is the impact of physical activity on neurogenesis in the hippocampus (Rhodes et al 2003b;Clark et al 2010; Rendeiro and Rhodes 2018), which, perhaps, could create a sort of feedback loop relating to running speed.…”

Reduced non-bicarbonate skeletal muscle buffering capacity in mice with the mini-muscle phenotype

“…The purpose of the present study was to examine muscle buffering capacity in replicate high-runner (HR) lines of mice that have experienced long-term breeding for high voluntary wheel running (Swallow et al, 1998). Several correlated responses in the HR lines seem to enhance capacity for endurance exercise, including more intermittent locomotion on wheels, altered stride characteristics during treadmill locomotion, increased maximal oxygen consumption (VȮ 2,max ), increased heart ventricle mass and larger femoral heads (Claghorn et al, 2017;Garland and Freeman, 2005;Girard et al, 2001;Kelly et al, 2017Kelly et al, , 2006Rezende et al, 2006).…”