A Simple and Inexpensive Running Wheel Model for Progressive Resistance Training in Mice

Summary

This procedure describes a translatable progressive loaded running wheel resistance training model in mice. The primary advantage of this resistance training model is that it is entirely voluntary, thus reducing stress for the animals and the burden on the researcher.

Abstract

Previously developed rodent resistance-based exercise models, including synergistic ablation, electrical stimulation, weighted-ladder climbing, and most recently, weighted-sled pulling, are highly effective at providing a hypertrophic stimulus to induce skeletal muscle adaptations. While these models have proven invaluable for skeletal muscle research, they are either invasive or involuntary and labor-intensive. Fortunately, many rodent strains voluntarily run long distances when given access to a running wheel. Loaded wheel running (LWR) models in rodents are capable of inducing adaptations commonly observed with resistance training in humans, such as increased muscle mass and fiber hypertrophy, as well as stimulation of muscle protein synthesis. However, the addition of moderate wheel load either fails to deter mice from running great distances, which is more reflective of an endurance/resistance training model, or the mice discontinue running nearly entirely due to the method of load application. Therefore, a novel high-load wheel running model (HLWR) has been developed for mice where external resistance is applied and progressively increased, enabling mice to continue running with much higher loads than previously utilized. Preliminary results from this novel HLWR model suggest it provides sufficient stimulus to induce hypertrophic adaptations over the 9 week training protocol. Herein, the specific procedures to execute this simple yet inexpensive progressive resistance-based exercise training model in mice are described.

Introduction

Skeletal muscle mass comprises approximately 40% of body mass in adult humans; thus, maintaining skeletal muscle mass throughout life is critical. Skeletal muscle mass plays an integral role in energy metabolism, maintaining core body temperature, and glucose homeostasis¹. The maintenance of skeletal muscle is a balance between protein synthesis and protein degradation, but many gaps still exist in the understanding of the intricate molecular mechanisms that drive these processes. To study the molecular mechanisms that regulate the maintenance and growth of muscle mass, human subjects' research models often employ resistance exercise-based ....

Protocol

This study was approved by Appalachian State University's Institutional Animal Care and Use Committee (#22-05).

1. Animals

1. Procure C57BL/6 mice from the in-house mouse colony.
   NOTE: Male mice 5-8 months of age at the start of the study were used. Daily running activity peaks and plateaus at around 9-10 weeks of age²⁶. Previous studies have demonstrated that old mice (22-24 months) will also perform loaded wheel running²⁷.
2. House the mice individually in a standard rodent cage with a wire lid and keep the cage in a controlled environment (20-24 °C with....

Results

In this study, 24 C57BL/6 mice (6.3 ± 0.7 months at the start of this study) were randomly assigned to one of three treatment groups: sedentary (SED), loaded wheel running (LWR; same as PoWeR described by Dungan et al.¹⁷), or high LWR (HLWR), and then completed their respective 9 week protocol. After the acclimation week (week 1), there were no group or group x time differences in running distance or training volume (Figure 5).

Discussion

Existing resistance exercise models in rodents have proven invaluable for skeletal muscle research; however, many of these models are invasive, involuntary, and/or time- and labor-intensive. LWR is an excellent model that not only induces similar muscular adaptations as those observed in other well-accepted resistance exercise training models, but also provides a chronic, low-stress exercise stimulus for the animal with minimal time/labor commitment by the researcher. Additionally, since LWR models require minimal direct.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1 g disc neodymium magnets	Applied Magnets	ND018-6	Used for all sensor magnets and 1 g increments of wheel loading
2.5 g disc neodymium magnets	Applied Magnets	ND022	Used for 2.5 g increments of wheel loading
8-32 x 1" stainless steel screws	Amazon		https://www.amazon.com/gp/product/B07939RS23/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
8-32 Wing Nuts	Amazon		https://www.amazon.com/gp/product/B07YYWW2SB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
10 µL pipette tip box (empty)	Thermo Scientific	2140	We used empty ART Pipette tip boxes, but any similar sized boxes/trays would suffice
Extreme Liquid Glue	Loctite
Laminin primary antibody	Novus Biologicals	NB300-144AF647	primary antibody conjugated with AF657; 1:200 in PBS containing 10% normal goat serum
Lithium 3 V battery	n/a	CR2032
M10 (3/16" x 1 1/4") stainless steel fender washers	Amazon		https://www.amazon.com/gp/product/B00OHUHEU8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
MyoVision: Automated Image Quantification Platform	Wen et al. (2017)	v1.0	https://www.uky.edu/chs/center-for-muscle-biology/myovision
Polycarbonate rodent cage (430 mm L x 290 mm W x 201 mm H), with narrow width stainless steel wired bar lid	Orchid Scientific	Polycarbonate Rat Cage Type II	https://orchidscientific.com/product/rat-cage/ - 1519974600758-c29bc1c5-6dfa
Sigma Sport 509 Bike Computer	Sigma Sport		Does not need to be this model in particular, but must have distance and time monitoring capabilities
Silent Spinner Running Wheel (mini 11.4 cm)	Kaytee	SKU# 100079369	https://www.kaytee.com/all-products/small-animal/silent-spinner-wheel