The Wellcome Trust for providing Open Access funding to Oxford University. Robert Deacon is a member of Oxford OXION group, funded by Wellcome Trust grant WT084655MA.

1. Apparatus
1.1 Kondziela's inverted screen test
The inverted screen is a 43 cm square of wire mesh consisting of 12 mm squares of 1 mm diameter wire (Figure 1). It is surrounded by a 4 cm deep wooden beading (which prevents the occasional mouse which attempts to from climbing on to the other side) (Figure 2).
1.2 Weights test
Seven weights constitute the apparatus. Each consists of a ball of tangled fine gauge stainless steel wire, a "scale collector" as used to prevent limestone scale formation in domestic kettles. The weight of this is small (7 g) but each scale collector is attached to a series of steel chain links, each weighing approximately 13 g. The number of links ranges from one to seven. Their weights are therefore: 20, 33, 46, 59, 72, 85 and 98 g (Figures 3 and 4).
2. Procedure
For all tests, bring the mice to the experimental room 5-20 min before testing to ensure they are properly awake. As a general rule, to allow recovery of muscular strength and a return to normal levels of arousal, rest the mice by a return to the home cage after each motor test.
<ol>
	<li>Kondziela's inverted screen test</li>
	<li>Procedure: Place the mouse in the center of the wire mesh screen, start a stopclock, rotate the screen to an inverted position over 2 sec, with the mouse's head declining first. Hold the screen steadily 40-50 cm above a padded surface. Note the time when the mouse falls off, or remove it when the criterion time of 60 sec is reached. Longer criterion times may be useful for some experiments.</li>
	<li>Scoring the inverted screen:</li>
</ol>
Falling between 1-10 sec = 1 
Falling between 11-25 sec = 2 
Falling between 26-60 sec = 3 
Falling after 60 sec = 4
Or, e.g. for 2 min: 
Falling between 1-10 sec = 1 
Falling between 11-25 sec = 2 
Falling between 26-60 sec = 3 
Falling between 61-90 sec = 4 
Falling after 90 sec = 5
3. Weights Test
Hold a mouse by the middle/base of the tail and lower it to allow it to grasp the first weight (20 g) which is lying on the laboratory bench. As it grasps the wire scale collector with its forepaws, start a stop clock and raise the mouse until the link is clear of the bench. A hold of three seconds is the criterion. If the mouse drops the weight in less than 3 sec, note the time it held the weight. Rest the mouse for about 10 sec and try it on the weight once again. If it fails three times, that terminates the trial, and the mouse is assigned the maximum time/weight achieved. If it holds it for 3 sec then try it on the next heaviest weight. If it lifts this for 3 sec, test it on the next heavier weight, after you have tested all its cagemates on the first weight. Again, it is given three chances to hold the weight for 3 sec. A final total score is calculated as the product of the number of links in the heaviest chain held for the full 3 sec, multiplied by the time (sec) it is held. If the heaviest weight is dropped before 3 sec an appropriate intermediate value is calculated. Thus a mouse holding a 5-link weight for 3 seconds, but unable to lift a 6-link weight, is assigned a score of (5 x 3) = 15. If it holds the 6-link weight for 1 second, it scores (5 x 3) + (1) =16.
Sometimes mice may not be adequately motivated to grip the apparatus. This generally occurs in older animals. This problem can be minimized by holding the mice by the tail for a longer time before bringing it within gripping distance of the wire ball.

<ol>
	<li>Bulfield, G., Siller, W. G., Wight, P. A., Moore, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=K.J.X+chromosome-linked+muscular+dystrophy+(mdx)+in+the+mouse.">K.J.X chromosome-linked muscular dystrophy (mdx) in the mouse.</a> Proc. Natl. Acad. Sci. U.S.A. 81, 1189-1192 (1984).</li><li>Contet, C., Rawlins, J. N. P., Deacon, R. M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparison+of+129S2/SvHsd+and+C57BL/6JOlaHsd+mice+on+a+test+battery+assessing+sensorimotor,+affective+and+cognitive+behaviours:+implications+for+the+study+of+genetically+modified+mice.">A comparison of 129S2/SvHsd and C57BL/6JOlaHsd mice on a test battery assessing sensorimotor, affective and cognitive behaviours: implications for the study of genetically modified mice.</a> Behavioural Brain Research. 124, 33-46 (2001).</li><li>Deacon, R. M. J., Brook, R. C., Meyer, D., Haeckel, O., Ashcroft, F. M., Miki, T., Seino, S., Liss, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+phenotyping+of+mice+lacking+the+KATP+channel+subunit+Kir6.2.">Behavioral phenotyping of mice lacking the KATP channel subunit Kir6.2.</a> Physiol. Behav. 87, 723-733 (2006).</li><li>Deacon, R. M. J., Croucher, A., Rawlins, J. N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hippocampal+cytotoxic+lesion+effects+on+species-typical+behaviors+in+mice.">Hippocampal cytotoxic lesion effects on species-typical behaviors in mice.</a> Behav. Brain Res. 132, 203-213 (2002).</li><li>Rawlins, J. N. P., Morley, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparison+of+the+behavior+of+C57BL/6+and+C57BL/10+mice.">A comparison of the behavior of C57BL/6 and C57BL/10 mice.</a> Behav. Brain Res. 179, 239-247 (2007).</li><li>Guenther, K., Deacon, R. M. J., Perry, V. H., Rawlins, J. N. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+behavioural+changes+in+scrapie-affected+mice+and+the+influence+of+dapsone.">Early behavioural changes in scrapie-affected mice and the influence of dapsone.</a> Eur. J. Neurosci. 14, 401-409 (2001).</li><li>Kondziela, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eine+neue+method+zur+messung+der+muskularen+relaxation+bei+weissen+mausen.">Eine neue method zur messung der muskularen relaxation bei weissen mausen.</a> Arch. Int. Pharmacodyn. 152, 277-284 (1964).</li></ol>

No conflicts of interest declared.

Mouse models of the many diseases that affect the human motor systems are continually being developed, therefore good assays of strength in mice are essential. Examples include the many forms of muscular dystrophy, Parkinson's disease and Huntington's chorea. Strength assays also find use in models of nerve regeneration after spinal or peripheral nerve damage. Industrial and automobile accidents continue to cause considerable disability to humans, but much preclinical work is presently investigating possible avenues of treatment based on nerve growth factors.
Muscles never work individually. They are activated by the brain, local or higher spinal reflexes, via the neuromuscular junctions and work within the constraints of other muscles and the skeletal system. Therefore, the complexity of the system means in vivo assays of muscular force in the awake animal are essential in the evaluation of its present condition and the effects of any putative treatments. Mice instinctively hold on to materials with a strong grip, thus Mus musculus is an ideal model animal in which to assess disorders of muscular strength and possible treatments.

To a lay person, the idea of measuring strength in mice might appear absurd, even something of an oxymoron. However, it is not without reason that house/lab mice are named Mus musculus. They actually have a very high strength/weight ratio, greater than that of rats. For instance, adult mice can easily support their own body weight, even using only the fore or hind paws; very few adult lab rats can do this.
Mice are playing an ever greater role in biomedical research. They can be used to model many human motor disorders, both somatic and central nervous system in origin. The former include the more than thirty forms of inherited muscular dystrophy1 and myasthenia gravis, while examples of the latter are multiple sclerosis, spinal muscular atrophy, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. For all of these models, a full assessment of their motor deficits must include specific tests of strength.

measuring the strength of mice

Kondziela7 devised the inverted screen test and published it in 1964. It is a test of muscle strength using all four limbs. Most normal mice easily score maximum on this task; it is a quick but insensitive gross screen, and the weights test described in this article will provide a finer measure of muscular strength.
There are also several strain gauge-based pieces of apparatus available commercially that will provide more graded data than the inverted screen test, but their cost may put them beyond the reach of many laboratories which do not specialize in strength testing. Hence in 2000 a cheap and simple apparatus was devised by the author. It consists of a series of chain links of increasing length, attached to a "fur collector" a ball of fine wire mesh sold for preventing limescale build up in hard water areas. An accidental observation revealed that mice could grip these very tightly, so they proved ideal as a grip point for a weight-lifting apparatus. A common fault with commercial strength meters is that the bar or other grip feature is not thin enough for mice to exert a maximum grip. As a general rule, the thinner the wire or bar, the better a mouse can grip with its small claws.
This is a pure test of strength, although as for any test motivational factors could potentially play a role. The use of scale collectors, however, seems to minimize motivational problems as the motivation appears to be very high for most normal young adult mice.

Expected Results
Contet et al.2 demonstrated that 129S2/sv mice performed similarly on the weights test to C57BL/6 mice. Female C57BL/6 mice scored approximately 15, 129 mice 17, which means they could lift approximately 5 chain links, around 70 g. This is a high value; normally 2-3 chain links (score 6-9, 33-46 g) are lifted by C57BL/6 mice5. These differences are presumably related to factors such as how much handling the mice have received and the details of the experimenter's technique.
Hippocampal lesions did not affect strength as measured either by the weights test or the inverted screen4. Prion (scrapie) diseased mice were impaired on the inverted screen by 18 weeks after infection6. Although somewhat impaired on the horizontal bar and rotarod relative to C57BL/6 mice, C57BL/10 mice were not impaired on weightlifting5. Knockout mice for the KATP channel subunit Kir6.2 were not impaired on the inverted screen or weightlifting tests, although the females scored higher than males on the latter3. This was unusual; normally the heavier males display greater strength than the females.
<img alt="Animal handling in behavioral research, wire grid for rodent study analysis, experiment setup." src="/files/ftp_upload/2610/2610fig1.jpg" data-altupdatedat="1747911167000" data-alt="Figure 1"> 
 Figure 1. The inverted screen.
<img alt="Small mammal on a cage wire, animal behavior study, rodent climbing experiment setup." src="/files/ftp_upload/2610/2610fig2.jpg" data-altupdatedat="1747911167000" data-alt="Figure 2"> 
 Figure 2. Close view of a mouse on the inverted screen.
<img alt="Corrosion experiment with steel wool and chains; rust formation; material degradation study." src="/files/ftp_upload/2610/2610fig3.jpg" data-altupdatedat="1747911167000" data-alt="Figure 3"> 
 Figure 3. Weights, ranging from 20 g to 98 g.
<img alt="Mouse static equilibrium test with tail suspension, force application; tension strength study setup." src="/files/ftp_upload/2610/2610fig4.jpg" data-altupdatedat="1747911167000" data-alt="Figure 4"> 
 Figure 4. A mouse weightlifting.

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Measuring the Strength of Mice

Deficits in muscular strength occur in many clinical conditions such as motor neuron disease. The inverted screen and weight lifting tests described here measure strength in mice almost exclusively, with minimal influence of factors such as coordination.

Kondziela7 devised the inverted screen test and published it in 1964. It is a test of muscle strength using all four limbs. Most normal mice easily score ...

Research

JoVE Journal

Medicine

54.1K Views.  University of Oxford. Tekorten in spierkracht optreden in veel klinische aandoeningen zoals motor neuron ziekte. De omgekeerde scherm en gewichtheffen testen hier beschreven maatregel kracht bij muizen bijna uitsluitend, met minimale invloed van factoren zoals de coördinatie.

Video: Measuring the Strength of Mice

Assessing Functional Performance in the Mdx Mouse Model

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential pharmaceutical compounds and gene therapy approaches have progressed into clinical trials. With improvement in muscle function being the most important end point in these trials, a lot of emphasis has been placed on setting up reliable, reproducible, and easy to perform functional tests to pre clinically assess muscle function, strength, condition, and coordination in the mdx mouse model for DMD. Both invasive and noninvasive tests are available. Tests that do not exacerbate the disease can be used to determine the natural history of the disease and the effects of therapeutic interventions (e.g. forelimb grip strength test, two different hanging tests using either a wire or a grid and rotarod running). Alternatively, forced treadmill running can be used to enhance disease progression and/or assess protective effects of therapeutic interventions on disease pathology. We here describe how to perform these most commonly used functional tests in a reliable and reproducible manner. Using these protocols based on standard operating procedures enables comparison of data between different laboratories.

Assessing Functional Performance in the Mdx Mouse Model

The primary outcome measure in clinical trials for neuromuscular disorders is generally improved muscle function. Therefore, assessing the effect of potential therapeutic compounds on muscle performance pre clinically in mouse models is of great importance. We here describe several functional tests to address this.

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential ...

Behavior

Measuring Motor Coordination in Mice

Mice are increasingly being used in behavioral neuroscience, largely replacing rats as the behaviorist's animal of choice. Before aspects of behavior such as emotionality or cognition can be assessed, however, it is vital to determine whether the motor capabilities of e.g. a mutant or lesioned mouse allow such an assessment. Performance on a maze task requiring strength and coordination, such as the Morris water maze, might well be impaired in a mouse by motor, rather than cognitive, impairments, so it is essential to selectively dissect the latter from the former. For example, sensorimotor impairments caused by NMDA antagonists have been shown to impair water maze performance2. 
Motor coordination has traditionally been assessed in mice and rats by the rotarod test, in which the animal is placed on a horizontal rod that rotates about its long axis; the animal must walk forwards to remain upright and not fall off. Both set speed and accelerating versions of the rotarod are available.
The other three tests described in this article (horizontal bar, static rods and parallel bars) all measure coordination on static apparatus. The horizontal bar also requires strength for adequate performance, particularly of the forelimbs as the mouse initially grips the bar just with the front paws. 
Adult rats do not perform well on tests such as the static rods and parallel bars (personal observations); they appear less well coordinated than mice. I have only tested male rats, however, and male mice seem generally less well coordinated than females. Mice appear to have a higher strength:weight ratio than rats; the Latin name, Mus musculus, seems entirely appropriate. The rotarod, the variations of the foot fault test12 or the Catwalk (Noldus)15 apparatus are generally used to assess motor coordination in rats.

Protocols are presented for two established motor coordination tasks, the accelerating rotarod and horizontal bar, also two tests developed in Oxford recently, the static rods and parallel bars. These tests can detect motor impairments potentially of interest in their own right, as well as being possible variables in tests of other areas of behavior.

Mice are increasingly being used in behavioral neuroscience, largely replacing rats as the behaviorist's animal of choice. Before aspects of behavior such ...

Neuroscience

Battery of Behavioral Tests Assessing General Locomotion, Muscular Strength, and Coordination in Mice

Behavioral testing is used in pre-clinical trials to assess the phenotypic effects and outcomes that a particular disease or treatment has on the animal&#39;s wellbeing and health. There are numerous behavioral tests that may be applied. We selected a test for general locomotion, the open field test (OFT); a test for muscular strength, the mesh test (MT); and a test for coordination, the rotarod test (RR). Testing can be accomplished on a weekly or monthly basis. As a test for general locomotion, the OFT works by objectively monitoring movement parameters while the mouse is in an open field apparatus. The field is generally a 2&#39; x 2&#39; box, and the movements are recorded through laser sensing or through video capture. The mouse is placed in the center of the open field and allowed to move freely for the test. The MT uses the latency for a mouse to fall off an inverted screen as a measure of muscular strength. A mouse is placed on a screen, which is inverted over a clear box, and is timed for their latency to fall. Three trials are performed, with the best of the three trials scored for that day. A score of 60 s is the maximum time a mouse is left inverted. Mice are given a 5-min rest period between mesh test trials. Lastly, an accelerated protocol on the RR assesses motor coordination and endurance. During a trial, a mouse walks on a rotating rod as it increases in speed from 4 rpm to 40 rpm over 5 min. The trial ends when the mouse touches the magnetized pressure sensor upon falling. Each mouse undergoes three trials, and the best trial is scored for that day. This combined behavioral data allows for the global assessment of mobility, coordination, strength, and movement of the test animals. At least two out of the three behavioral testing measures must show improvement for an animal to qualify as having overall improved motor function.

Behavioral testing is used in pre-clinical trials to assess the phenotypic effects of a disease or treatment on an animal's wellbeing. In order to globally assess motor functioning, we selected tests for general locomotion, muscular strength, and coordination: the open field test, the mesh test, and the rotarod test, respectively.

Behavioral testing is used in pre-clinical trials to assess the phenotypic effects and outcomes that a particular disease or treatment has on the ...

Systematic Assessment of Well-Being in Mice for Procedures Using General Anesthesia

In keeping with the 3R Principle (Replacement, Reduction, Refinement) developed by Russel and Burch, scientific research should use alternatives to animal experimentation whenever possible. When there is no alternative to animal experimentation, the total number of laboratory animals used should be the minimum needed to obtain valuable data. Moreover, appropriate refinement measures should be applied to minimize pain, suffering, and distress accompanying the experimental procedure. The categories used to classify the degree of pain, suffering, and distress are non-recovery, mild, moderate, or severe (EU Directive 2010/63). To determine which categories apply in individual cases, it is crucial to use scientifically sound tools.
The well-being-assessment protocol presented here is designed for procedures during which general anesthesia is used. The protocol focuses on home cage activity, the Mouse Grimace Scale, and luxury behaviors such as burrowing and nest building behavior as indicators of well-being. It also uses the free exploratory paradigm for trait anxiety-related behavior. Fecal corticosterone metabolites as indicators of acute stress are measured over the 24-h post-anesthetic period.
The protocol provides scientifically solid information on the well-being of mice following general anesthesia. Due to its simplicity, the protocol can easily be adapted and integrated in a planned study. Although it does not provide a scale to classify distress in categories according to the EU Directive 2010/63, it can help researchers estimate the degree of severity of a procedure using scientifically sound data. It provides a way to improve the assessment of well-being in a scientific, animal-centered manner.

We developed a protocol to assess well-being in mice during procedures using general anesthesia. A series of behavioral parameters indicating levels of well-being as well as glucocorticoid metabolites were analyzed. The protocol can serve as a general aid to estimate the degree of severity in a scientific, animal-centered manner.

In keeping with the 3R Principle (Replacement, Reduction, Refinement) developed by Russel and Burch, scientific research should use alternatives to animal ...

Measuring Active and Passive Tameness Separately in Mice

Domesticated animals such as dogs and laboratory mice show a high level of tameness, which is important for humans to handle them easily. Tameness has two behavioral components: a reluctance to avoid humans (passive tameness) and a motivation to approach humans (active tameness). To quantify these components in mice, we previously developed behavioral tests for active tameness, passive tameness, and the willingness to stay on a human hand, each designed to be completed within 3 min. The data obtained were used for selective breeding, with a large number of mice analyzed per generation. The active tameness test measures the movement of the mouse toward a human hand and the contact it engages in. The passive tameness test measures the duration of time that a mouse tolerates human touch. In the stay-on-hand test, a mouse is placed on a human hand and touched slowly using the thumb of that hand; the duration of time that the animal remains on the hand is measured. Here, we describe the test set-up and apparatus, explain the procedures, and discuss the appropriate data analysis. Finally, we explain how to interpret the results.

Tameness in animals includes a reduction of avoidance responses to humans (passive tameness) and an increase in active approaches to humans (active tameness). Here, we describe detailed protocols for three behavioral tests (active tameness, passive tameness, and stay-on-hand tests) to separately measure the active and passive tameness of mice.

Domesticated animals such as dogs and laboratory mice show a high level of tameness, which is important for humans to handle them easily. Tameness has two ...

Measuring Changes in Tactile Sensitivity in the Hind Paw of Mice Using an Electronic von Frey Apparatus

Measuring inflammation-induced changes in thresholds of hind paw withdrawal from mechanical pressure is a useful technique to assess changes in pain perception in rodents. Withdrawal thresholds can be measured first at baseline and then following drug, venom, injury, allergen,&#160;or otherwise evoked inflammation by applying an accurate force on very specific areas of the skin. An electronic von Frey apparatus allows precise assessment of mouse hind paw withdrawal thresholds that are not limited by the available filament sizes in contrast to classical von Frey measurements. The ease and rapidity of measurements allow for incorporation of assessment of tactile sensitivity outcomes in diverse models of rapid-onset inflammatory and neuropathic pain as multiple measurements can be taken within a short time period. Experimental measurements for individual rodent subjects can be internally controlled against individual baseline responses and exclusion criteria easily established to standardize baseline responses within and across experimental groups. Thus, measurements using an electronic von Frey apparatus represent a useful modification of the well-established classical von Frey filament-based assays for rodent mechanical allodynia that may also be applied to other nonhuman mammalian models.

Electronic von Frey measurements are an effective and improved alternative to classical von Frey filaments, as they allow rapid and precise measurement of changes in rodent mechanical withdrawal thresholds to continuously applied pressure stimuli before and after an inflammatory event.

Measuring inflammation-induced changes in thresholds of hind paw withdrawal from mechanical pressure is a useful technique to assess changes in pain ...

Non-invasive Assessment of Dorsiflexor Muscle Function in Mice

Assessment of skeletal muscle contractile function is an important measurement for both clinical and research purposes. Numerous conditions can negatively affect skeletal muscle. This can result in a loss of muscle mass (atrophy) and/or loss of muscle quality (reduced force per unit of muscle mass), both of which are prevalent in chronic disease, muscle-specific disease, immobilization, and aging (sarcopenia). Skeletal muscle function in animals can be evaluated by a range of different tests. All tests have limitations related to the physiological testing environment, and the selection of a specific test often depends on the nature of the experiments. Here, we describe an in vivo, non-invasive technique involving a helpful and easy assessment of force frequency-curve (FFC) in mice that can be performed on the same animal over time. This permits monitoring of disease progression and/or efficacy&#160;of a potential therapeutic treatment.

Measurement of rodent skeletal muscle contractile function is a useful tool that can be used to track disease progression as well as efficacy of therapeutic intervention. We describe here the non-invasive, in vivo assessment of the dorsiflexor muscles that can be repeated over time in the same mouse.

Assessment of skeletal muscle contractile function is an important measurement for both clinical and research purposes. Numerous conditions can negatively ...

Mechanical Conflict-Avoidance Assay to Measure Pain Behavior in Mice

Pain comprises of both sensory (nociceptive) and affective (unpleasant) dimensions. In preclinical models, pain has traditionally been assessed using reflexive tests that allow inferences regarding pain's nociceptive component but provide little information about the affective or motivational component of pain. Developing tests that capture these components of pain are therefore translationally important. Hence, researchers need to use non-reflexive behavioral assays to study pain perception at that level. Mechanical conflict-avoidance (MCA) is an established voluntary non-reflexive behavior assay, for studying motivational responses to a noxious mechanical stimulus in a 3 chamber paradigm. A change in a mouse's location preference, when faced with competing noxious stimuli, is used to infer the perceived unpleasantness of bright light versus tactile stimulation of the paws. This protocol outlines a modified version of the MCA assay which pain researchers can use to understand affective-motivational responses in a variety of mouse pain models. Though not specifically described here, our example MCA data use the intraplantar complete Freund's adjuvant (CFA), spared nerve injury (SNI), and a fracture/casting model as pain models to illustrate the MCA procedure.

The mechanical conflict-avoidance assay is used as a non-reflexive readout of pain sensitivity in mice which can be used to better understand affective-motivational responses in a variety of mouse pain models.

Pain comprises of both sensory (nociceptive) and affective (unpleasant) dimensions. In preclinical models, pain has traditionally been assessed using ...

In vivo Measurement of Knee Extensor Muscle Function in Mice

Skeletal muscle plasticity in response to countless conditions and stimuli mediates concurrent functional adaptation, both negative and positive. In the clinic and the research laboratory, maximal muscular strength is widely measured longitudinally in humans, with knee extensor musculature the most reported functional outcome. Pathology of the knee extensor muscle complex is well documented in aging, orthopedic injury, disease, and disuse; knee extensor strength is closely related to functional capacity and injury risk, underscoring the importance of reliable measurement of knee extensor strength. Repeatable, in vivo assessment of knee extensor strength in pre-clinical rodent studies offers valuable functional endpoints for studies exploring osteoarthritis or knee injury. We report an in vivo and non-invasive protocol to repeatedly measure isometric peak tetanic torque of the knee extensors in mice across time. We demonstrate consistency using this novel method to measure knee extensor strength with repeated assessment in multiple mice producing similar results.

Quantification of knee extensor maximal strength is imperative to understand functional adaptations to aging, disease, injury, and rehabilitation. We present a novel method to repeatedly measure in vivo knee extension isometric peak tetanic torque.

Skeletal muscle plasticity in response to countless conditions and stimuli mediates concurrent functional adaptation, both negative and positive. In the ...

Biology

Versatility of Protocols for Resistance Training and Assessment Using Static and Dynamic Ladders in Animal Models

Resistance training is a physical exercise model with profound benefits for health throughout life. The use of resistance exercise animal models is a way to gain insight into the underlying molecular mechanisms that orchestrate these adaptations. The aim of this article is to describe exercise models and training protocols designed for strength training and evaluation of resistance in animal models and provide examples. In this article, strength training and resistance evaluation are based on ladder climbing activity, using static and dynamic ladders. These devices allow a variety of training models as well as provide precise control of the main variables which determine resistance exercise: volume, load, velocity, and frequency. Furthermore, unlike resistance exercise in humans, this is a forced exercise. Thus, aversive stimuli must be avoided in this intervention to preserve animal welfare. Prior to implementation, a detailed design is necessary, along with an acclimatization and learning period. Acclimatization to training devices, such as ladders, weights, and clinical tape, as well as to the manipulations required, is necessary to avoid exercise rejection and to minimize stress. At the same time, the animals are taught to climb up the ladder, not down, to the resting area on the top of the ladder. Resistance evaluation can characterize physical strength and permit adjusting and quantifying the training load and the response to training. Furthermore, different types of strength can be evaluated. Regarding training programs, with appropriate design and device use, they can be sufficiently versatile to modulate different types of strength. Furthermore, they should be flexible enough to be modified depending on the adaptive and behavioral response of the animals or the presence of injuries. In conclusion, resistance training and assessment using ladders and weights are versatile methods in animal research.

The present protocol describes resistance training and testing using static and dynamic ladders in animal models.

Resistance training is a physical exercise model with profound benefits for health throughout life. The use of resistance exercise animal models is a way ...

Measuring the Strength of Mice

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