Muscle Health and Exercise Performance
Exercise Endurance
Rationale: Measure exercise and endurance in rodents.
Instrument: ExerGait treadmill (Columbus Instruments, TreadScan™ 1.0 software, CleverSys Inc).
Measure: Animals are placed on a treadmill of six lanes (mouse), or three lanes (rats) utilizing a single belt construction with dividing walls suspended over the tread surface. An electric stimulus option is available, provided by shock grids with individual on/off switches. Animals are allowed to run in the treadmill with different schedules depending on the measure to be obtained. For endurance training, animals are prompted to continue running using a mild electric shock. Intensity is adjustable and the treadmill is connected to a motor controller that allows for the adjustment of speed in range of 3-100m/m.
Data Inference: For endurance testing, the animals are exercised for a short duration on successive days until testing day. For exercise training, the animals are trained for repeated sessions for specific interval of time.
Controls: Subject to type of assay being performed.
Gait Analysis (Treadscan)
Rationale: This test measures the pattern of movement of the limbs of animals during locomotion over a motion belt.
Instrument: ExerGait Treadmill from Columbus Instruments. Treadscan Software from Clever Sys Inc.
Measures: Animals are tested on the ExerGait treadmill inside an adjustable running space at a fixed speed of 15 cm/sec for 10 sec. A digital camera records the reflected images of the footpads. Output was fed directly to a computer. Video recordings are analyzed by TreadScan™ 1.0 software (Clever Sys Inc.).
Data Inference: Averages from strides within a 20 – 100 mm range, and average length of front, rear and total strides are collected. Over 40 parameters can be obtained from data analysis.
Controls: Treadmill speed needs to be carefully adjusted until the mouse can maintain a consistent walking speed.
Grip and Limb Strength
Rationale: Measure muscular strength and assess neuromuscular function.
Instrument: Grip Strength Force Meter (Columbus Instruments).
Measures: The instrument senses the peak amount of force required to make the mouse release its grip on the apparatus. Mice are lifted over the baseplate by the tail so that its forepaws are allowed to grasp onto the steel grip. The operator gently pulls backwards until the grip is released.
Data Inference: The meter measures the maximal grams force (GF) before the mouse releases the stainless steel grid.
Controls: Care is taken to keep operator constant for all groups in an experiment.
Muscle Force Generation and Fatigability
Rationale: Measure muscle contractile force.
Instrument: Aurora Scientific Inc, 1300A-whole Mouse Test System DMC/DMA Dynamic Muscle Control and Analysis Software.
Measures: Assessed in rodent hindlimbs (in vivo) and in isolated muscles and strips (ex vivo) using a muscle physiology system
Data Inference: Maximal contraction force for each measurement provide a measure of contractile force.
Controls: Care is taken to ensure that the leg muscle is in a relaxed state.