The authors have no acknowledgements.

The following procedures are in accordance with the standards of the Brigham Young University Institutional review board (IRB).
1. Prepare the Contraction Protocols
NOTE: The following protocol instructions are based on the Biodex Advantage software. Navigating the software and operating the dynamometer will be different if different systems are used.
<ol>
	<li>Isokinetic Strength Test Protocol
	<ol>
		<li>To make the isokinetic protocol, open dynamometer control ...

<ol>
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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Satellite+cell+activity+is+differentially+affected+by+contraction+mode+in+human+muscle+following+a+work-matched+bout+of+exercise.">Satellite cell activity is differentially affected by contraction mode in human muscle following a work-matched bout of exercise.</a> Front. Physiol. 5, 485 (2014).</li><li>Clarkson, P. M., Kearns, A. K., Rouzier, P., Rubin, R., Thompson, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+creatine+kinase+levels+and+renal+function+measures+in+exertional+muscle+damage.">Serum creatine kinase levels and renal function measures in exertional muscle damage.</a> Med. Sci. Sports Exerc. 38 (4), 623-627 (2006).</li><li>Clarkson, P. 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E., Kenney, K., Deuster, P., Campbell, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exertional+rhabdomyolysis:+a+clinical+review+with+a+focus+on+genetic+influences.">Exertional rhabdomyolysis: a clinical review with a focus on genetic influences.</a> J. Clin. Neuromuscul. Dis. 13 (3), 122-136 (2012).</li><li>Warren, G. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+CC+chemokines+in+skeletal+muscle+functional+restoration+after+injury.">Role of CC chemokines in skeletal muscle functional restoration after injury.</a> Am. J. Physiol. Cell Physiol. 286 (5), C1031-C1036 (2004).</li><li>Zhang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD8+T+cells+are+involved+in+skeletal+muscle+regeneration+through+facilitating+MCP-1+secretion+and+Gr1(high)+macrophage+infiltration.">CD8 T cells are involved in skeletal muscle regeneration through facilitating MCP-1 secretion and Gr1(high) macrophage infiltration.</a> J. Immunol. 193 (10), 5149-5160 (2014).</li><li>Cermak, N. M., Noseworthy, M. D., Bourgeois, J. M., Tarnopolsky, M. A., Gibala, 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=Diffusion+tensor+MRI+to+assess+skeletal+muscle+disruption+following+eccentric+exercise.">Diffusion tensor MRI to assess skeletal muscle disruption following eccentric exercise.</a> Muscle Nerve. 46 (1), 42-50 (2012).</li><li>Chen, Y. W., Hubal, M. J., Hoffman, E. P., Thompson, P. D., Clarkson, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+responses+of+human+muscle+to+eccentric+exercise.">Molecular responses of human muscle to eccentric exercise.</a> J. Appl. Physiol. 95 (6), 2485-2494 (2003).</li><li>Stasinger, S. K., Di Lorenzo, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Phlebotomy Textbook. , 188-203 (2011).</li><li>Hubal, M. J., Chen, T. C., Thompson, P. D., Clarkson, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammatory+gene+changes+associated+with+the+repeated-bout+effect.">Inflammatory gene changes associated with the repeated-bout effect.</a> Am. J. Physiol. Regul. Integr. Comp. Physiol. 294 (5), R1628-R1637 (2008).</li><li>Stupka, N., Tarnopolsky, M. A., Yardley, N. J., Phillips, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+adaptation+to+repeated+eccentric+exercise-induced+muscle+damage.">Cellular adaptation to repeated eccentric exercise-induced muscle damage.</a> J. Appl. Physiol. 91 (4), 1669-1678 (2001).</li><li>Smith, L. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+serum+cytokines+after+repeated+bouts+of+downhill+running.">Changes in serum cytokines after repeated bouts of downhill running.</a> Appl. Physiol. Nutr. Metab. 32 (2), 233-240 (2007).</li><li>Marqueste, T., Giannesini, B., Fur, Y. L., Cozzone, P. J., Bendahan, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+MRI+analysis+of+T2+changes+associated+with+single+and+repeated+bouts+of+downhill+running+leading+to+eccentric-induced+muscle+damage.">Comparative MRI analysis of T2 changes associated with single and repeated bouts of downhill running leading to eccentric-induced muscle damage.</a> J. Appl. Physiol. 105 (1), 299-307 (2008).</li><li>Crameri, R. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myofibre+damage+in+human+skeletal+muscle:+effects+of+electrical+stimulation+versus+voluntary+contraction.">Myofibre damage in human skeletal muscle: effects of electrical stimulation versus voluntary contraction.</a> J. Physiol. 583 (Pt 1), 365-380 (2007).</li><li>Yu, J. G., Malm, C., Thornell, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eccentric+contractions+leading+to+DOMS+do+not+cause+loss+of+desmin+nor+fibre+necrosis+in+human+muscle.">Eccentric contractions leading to DOMS do not cause loss of desmin nor fibre necrosis in human muscle.</a> Histochem. Cell Biol. 118 (1), 29-34 (2002).</li><li>Jamurtas, A. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+between+leg+and+arm+eccentric+exercises+of+the+same+relative+intensity+on+indices+of+muscle+damage.">Comparison between leg and arm eccentric exercises of the same relative intensity on indices of muscle damage.</a> Eur. J. Appl. Physiol. 95 (2-3), 179-185 (2005).</li></ol>

The authors have nothing to disclose.

Several steps are critical to obtaining the desired results of this protocol. First, subjects must be adequately familiarized to the contraction protocols, particularly the force measurements. Be sure that the subject understands exactly what they are expected to do and give them an opportunity to practice the strength tests prior to data collection. Subjects who are not adequately familiarized with these procedures may show a learning curve over the days following the damage induction. This can be a confounding variable...

The overall goal of this procedure is to induce exertional damage to the quadriceps femoris muscles using voluntary lengthening (eccentric) contractions in human subjects.
Contraction-induced skeletal muscle damage is a common consequence of exercise that is marked by delayed onset muscle soreness1, transient strength loss, and elevated muscle-specific enzymes in the blood2. Exertional muscle damage is most pronounced following exercise to which the subject is unaccustomed, particularly when eccentric contractions are involved3. Exertional muscle damage is typically benign. Soreness subsides, and both serum proteins and strength typically return to pre-damage levels within a few days to weeks after the damaging insult. In extreme cases, exertional muscle damage can lead to a life-threatening syndrome know as rhabdomyolysis. However, exertional muscle damage is usually insufficient to cause clinical rhabdomyolysis in healthy individuals4 in the absence of compounding factors including heat stress, dehydration5, infection6 or rare genetic predispositions7. 
Contraction-induced muscle damage is typically less severe than toxin-induced or freezing-induced injury, methods often used in rodent studies8,9. Yet, contraction-induced injury provides a useful method to study the muscle damage response with notable advantages. First, it is a safe and ethical method for use with human subjects1-3. Thus, interspecies translation of the results is not needed as data can be obtained directly from human subjects. Moreover, translating data obtained from rodent studies is very difficult given that the severity of injury seen in the rodent injury models exceeds the level of damage that would be ethical to induce in human subjects. Second, contraction-induced damage is commonly experienced and a natural process of exercise. Therefore, this mode of damage induction is useful for studying muscle damage in the context of exercise, adaptation to exercise as well as overt muscle injury. Here we describe a safe and reliable method to induce and evaluate skeletal muscle damage using lengthening contractions in humans.

<table border="0" cellpadding="0" cellspacing="0" width="924">
	<tbody>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">Biodex Dynomometer</td>
			<td style="width:167px;">Biodex Medical Systems</td>
			<td style="width:119px;">850-000</td>
			<td style="width:423px;">Other models are available and should produce similar results</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Creatine Kinase kit</td>
			<td style="width:167px;">Sigma-Aldrich&#160;</td>
			<td>MAK116</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Serum Vacutainers</td>
			<td style="width:167px;">BD Bioscience</td>
			<td style="width:119px;">367812</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Winged safety push button blood collection set</td>
			<td style="width:167px;">BD Bioscience</td>
			<td style="width:119px;">367338</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cryogenic vials</td>
			<td style="width:167px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">V5007</td>
			<td>We use the 2mL vials to store serum aliquots</td>
		</tr>
	</tbody>
</table>

induction and assessment of exertional skeletal muscle damage in humans

Contraction-induced muscle damage via voluntary eccentric (lengthening) contractions offers an excellent model for studying muscle adaptation and recovery in humans. Herein we discuss the design of an eccentric exercise protocol to induce damage in the quadriceps muscles, marked by changes in strength, soreness, and plasma creatine kinase levels. This method is simple, ethical, and widely applicable since it is performed in human participants and eliminates the interspecies translation of the results. Subjects perform 300 maximal eccentric contractions of the knee extensor muscles at a speed of 120&#176;/sec on an isokinetic dynamometer. The extent of the damage is measurable using relatively non-invasive isokinetic and isometric measures of strength loss, soreness, and plasma creatine kinase levels over several days following the exercise. Therefore, its application can be directed to specific populations in an attempt to identify mechanisms for muscle adaptation and regeneration.

Using the methods presented here, baseline soreness, serum creatine kinase activity, and strength (isometric and isokinetic) measurements were taken in 7 untrained young men. The following day, the subjects underwent the muscle damaging eccentric contraction protocol described above. To provide indices of muscle damage, follow up assessments of strength, soreness and serum creatine kinase activity were made. Strength was measured immediately after as well as 24, 48, 72, and 96 hr after ex...

Watch this Scientific Journal Video about Induction and Assessment of Exertional Skeletal Muscle Damage in Humans at JoVE.com

Induction and Assessment of Exertional Skeletal Muscle Damage in Humans

This article describes a safe and reliable method to induce and quantify exertional skeletal muscle damage in human subjects.

Contraction-induced muscle damage via voluntary eccentric (lengthening) contractions offers an excellent model for studying muscle adaptation and recovery ...

The overall goal of this procedure is to safely induce and quantify exertional skeletal muscle damage to the quadriceps femoris muscles in human subjects using voluntary eccentric contractions. This muscle damage protocol can help researchers answer key questions regarding the mechanisms of muscle adaptation and regeneration following injury. The main advantage of this technique it that we can study the processes of muscle adaptation in human subjects, eliminating the need for interspecies translation of the results.While this method can be used to study muscle damage in the context of exercise, it can also be used to study damage caused by overt injury. Demonstrating the procedure will be Jake Sorensen, a PhD student from my laboratory. To create the isokinetic strength test protocol, begin by opening the dynamometer control software on the computer.Select new protocol from the dropdown list, then on the unilateral tab, program one set of three repetitions at a speed of 60 degrees per second for both the away and toward contractions by entering one into the number sets field, typing three in the end by reps row, and typing 60 in both the speed away and speed toward rows. Next, create an isometric strength test with one set of three isometric contractions lasting five seconds each at a joint angle of 70 degrees by typing a one into the positions field on the unilateral tab and typing a three into the end by reps row under the position one column. Then select 70 in the row labeled angle.Next, program the muscle damaging eccentric exercise protocol by clicking the unilateral tab and typing 10 into the number of sets field. In the first column, type 10 in the row labeled end by reps. Then type 180 in the next row, labeled speed away and 120 in the row labeled speed toward.Lastly, in the row labeled torque, type 200 to 600 depending on the anticipated strength of the subject, and enter 60 into the field labeled rest time in seconds. Begin by making a visual analog scale by drawing a 100 millimeter line horizontally across a page. On the left hand side of the line, indicate no soreness, and on the right hand side of the line, indicate extreme soreness.Next, escort the subject into the testing room, and instruct them to do two body weight squats to collect baseline soreness measurements. Perform both squats with arms help straight out in front of the shoulders, and feet shoulder width apart, in which proper depth is reached once the upper legs are parallel to the floor. Then, ask the subject to indicate the intensity of the soreness he or she felt in the quadriceps femoris muscles during the squats by drawing a vertical line at the appropriate spot on the visual analog scale.Finally quantify the subjects level of soreness by measuring the distance in millimeters from the no soreness end of the visual analog scale to the subject's mark. After a brief warmup on a cycle ergometer, ask the subject to sit in the chair of the dynamometer. Adjust the dynamometer position settings such that the rotational axis of the knee aligns with that of the lever arm, and secure the leg to the shaft arm.Record these settings for repeatable set up in the future. Stabilize the subject with shoulder, hip, ankle, and thigh straps. Next, inform the subject that they will be contracting against the lever arm that will remain stationary.You should instruct the subject according to the prompts on the computer screen to complete three contractions lasting five seconds each. Start the isometric protocol on the computer. Set the ROM limits, calibrate the dynamometer, and allow the subject to practice the test two to three times with submaximal effort in order to familiarize the subject to the test.Once the subject is ready, ask them to cross their arms across their chest. Start the test, and verbally encourage the subject to provide maximal effort for each contraction. Record baseline measurements of torque, power, and work.Allow the subject two to three minutes to rest, and then load the isokinetic strength test protocol on the computer. Inform the subject that they will complete three extension and flexion contractions against the lever arm that will move at a fixed rate. Let them know that the lever arm will stop when they reach the end of the range of motion, and the goal is to contract as forcefully as possible throughout the entire range of motion for each contraction.After a few submaximal practice tests to familiarize the subject, ask them to cross their arms across their chest, and start the test. Verbally encourage the subject to provide maximal effort, and to breathe normally. Record baseline measurements of torque, power, and work.One to three days after collecting the isometric and isokinetic baseline measurements, have the subject return to the lab to complete the muscle damaging eccentric exercise protocol. After a warmup, orient and secure the subject in the dynamometer using the previously recorded adjustment settings and load the exercise protocol. Instruct the subject to contract against the lever arm to initiate the movement of the shaft arm for each contraction.Then, explain that as the shaft arm moves toward them at a fixed rate, their goal is to contract against it as forcefully as possible. When the subject is ready, start the first set of contractions by pushing the start button on the screen, and as they perform the eccentric contractions, verbally encourage them to maintain maximal effort for each contraction. Finally, immediately after the muscle damaging exercise, repeat both isokinetic and isometric strength tests as well as at 24, 48, 72, and 96 hours after.Additionally, repeat the soreness measurement at 24, 48, 72, and 96 hours after the exercise test. Results from seven untrained young men show that compared to pre-exercise, isometric and isokinetic force was decreased out to 24 and 48 hours post exercise, respectively, and returned similar to pre-exercise values thereafter. Conversely, soreness was significantly increased at 24, 48, and 72 hours after exercise.Once mastered, this technique can be done safely and reliably if it's performed properly. Remember that it's important to consider the physical limitations of each subject and adapt the parameters accordingly. The joint angle parameters in the protocol should be reduced for individuals with limited range of motion and the target force should be reduced for weaker individuals.Following this procedure, other methods like obtaining a blood or muscle sample can be performed in order to answer additional questions related to the cellular and molecular responses to damage. After watching this video, you should have a good understanding of how to safely and ethically induce and quantify exertional muscle damage in human subjects. Lastly, don't forget that this protocol has the small potential to cause rhabdomyolysis.Subjects should be screened for signs and symptoms of rhabdomyolysis, which include dark brown urine, nausea, and extreme muscle weakness during the followup visits.

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7.4K visualizações.  Brigham Young University. The overall goal of this procedure is to safely induce and quantify exertional skeletal muscle damage to the quadriceps femoris muscles in human subjects using voluntary eccentric contractions. This muscle damage protocol can help researchers answer key questions regarding the mechanisms of muscle adaptation and regeneration following injury. The main advantage of this technique it that we can study the processes of muscle adaptation in human subjects, eliminating the need for interspecies tr...