immediate effects of acupuncture and cryotherapy on...

Original paper

Park J, Hopkins JT. Acupunct Med (2012). doi: 10.1136/acupmed-2012-010144 1 of 8

ABSTRACTObjective The authors asked the following

research questions: will an anterior knee infusion

model induce constant pain? will perceived pain

alter motoneuron pool (MNP) excitability? and will

treatments alter perceived pain and/or MNP

excitability?

Methods Thirty-six neurologically healthy

volunteers participated in this randomised controlled

laboratory study. To induce anterior knee pain (AKP),

5% hypertonic saline (0.12 ml/min with a total

volume of 8.5 ml over 70 min) was injected into the

infrapatellar fat pad of the dominant leg. One of four

30-min treatments was randomly assigned to each

subject after pain was induced (acupuncture,

cryotherapy, sham cryotherapy and no treatment).

Five acupuncture needles (SP9, SP10, ST36, GB34

and an ah shi point) were inserted to a depth of

1 cm. Vastus medialis (VM) maximum Hoffmann

refl exes normalised by maximum motor response

were recorded from each subject at baseline, 20

min post-injection, 50 min post-injection and 70 min

post-injection. To record pain perception, a visual

analogue scale was used every 5 min after injection.

Results An anterior knee infusion pain model

increased perceived pain (p<0.0001). No change

was found in VM MNP excitability among the four

treatments (p<0.19) or at any of the time intervals

(p<0.52). Cryotherapy reduced perceived pain

compared with acupuncture (p=0.0003) and sham

treatment (p=0.0002).

Conclusions A pain model may be used in other

neurophysiological intervention studies related to

AKP. AKP alone may not directly alter quadriceps

activation. None of the treatments altered VM MNP

excitability. Cryotherapy reduced pain while a

single session of acupuncture and sham

treatments did not.

Quadriceps inhibition associated with anterior knee pain (AKP) has been suggested in indi-viduals with clinical pain.1 AKP is believed to cause abnormal sensory input to the cen-tral nervous system, which may reduce the excitability of the α-motorneuron in the surrounding musculature.2 3 However, the direct relationship between pain and muscle activation is inconclusive because swelling, infl ammation and structural damage may

confound the results.3–6 To remove the other factors associated with clinical knee pain, researchers have used an induced pain model. An injection of 5% hypertonic saline into the infrapatellar fad pad causes chemical irritation, resulting in an increase in nociceptor activity.7 This has been considered to be a safe and effective injury model for examining neuro-muscular activity changes under the condition of isolated pain.8 9

Although the artifi cial pain model quickly induces moderate dull and achy pain,7–10 the induced pain only lasts approximately 10 min.7 9 A single injection pain model is lim-ited to studies in which the measurements or interventions take less than 10 min. A con-tinuous infusion of 5% hypertonic saline has previously been used in muscle to elicit longer-lasting pain.11–13 We hypothesised that a con-tinuous infusion of 5% hypertonic saline into the infrapatellar fat pad would also induce a longer constant AKP allowing longer measure-ments to be taken or interventions to be used.

Multiple sessions of acupuncture treatments have been shown to reduce pain in patients with AKP14 15 and knee osteoarthritis.16 17 Activation of somatic afferents in peripheral nerves by acupuncture needle stimulation has been considered to be a primary neuro-physiological mechanism behind the effects on pain reduction.18 Increased activity in A-δ and C-fi bres due to noxious stimulation may release β-endorphins and enkephalins, result-ing in analgesic effects.19 Acupuncture may also produce psychological (placebo) effects15 20 to evoke an increase in the release of endogenous opioids,19 resulting in central pain inhibition. In addition, a single session of acupuncture treat-ment immediately increased maximal volun-tary quadriceps torque in healthy individuals.21 However, potential changes in motoneuron pool (MNP) excitability due to acupuncture treatments in patients experiencing isolated AKP have never been examined.

Cold application has been widely used to decrease pain22 23 and facilitate active exercise.24

25 Knee joint cooling has increased quadriceps activation in individuals with tibiofemo-ral osteoarthritis,26 artifi cial effusion27 and in healthy knees.28 Neurophysiological

Immediate effects of acupuncture and cryotherapy on quadriceps motoneuron pool excitability: randomised trial using anterior knee infusion modelJihong Park, J Ty Hopkins

Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA

Correspondence to Jihong Park, 106 SFH, Department of Exercise Sciences Brigham Young University, Provo, UT 84602, USA; [email protected]

Accepted 4 May 2012

Copyright 2012 by British Medical Journal Publishing Group.

on 26 May 2018 by guest. P

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Original paper

Park J, Hopkins JT. Acupunct Med (2012). doi: 10.1136/acupmed-2012-0101442 of 8

response following a cold application may include a reduction in nerve conduction velocity,4 discharge rate of receptors29 and receptor sensitivity.30 Cryotherapy also stimulates cutaneous mechanoreceptors that excite Ia interneurons, resulting in excitatory potentials at the MNP.27 However, little is known about how cryother-apy effectively reverses quadriceps inhibition in iso-lated AKP individuals.

The purpose of this study was to examine the imme-diate effects of cryotherapy and acupuncture on vastus medialis (VM) MNP excitability in subjects with experi-

mentally induced AKP. We asked the following research questions: will an anterior knee infusion model induce constant AKP? If so, will perceived AKP alter quadriceps MNP excitability? And will treatments (acupuncture, cryotherapy, sham and control-no treatment and no injec-tion) alter perceived AKP and/or MNP excitability? We hypothesised that an anterior knee infusion model would produce constant AKP, an increased knee pain would decrease quadriceps MNP excitability and acupuncture and cryotherapy would reverse quadriceps inhibition and decrease perceived knee pain.

Figure 1 CONSORT fl owchart. VM, vastus medialis.

Assessed for eligibility(n=112)

Randomised(n=40)

Excluded (n=72)

- Immeasurable VM H-reflex (n=72)

Allocated intervention Acupuncture (n=10)

Received allocated intervention (n=10)

Did not receive allocated intervention (n=0)

Analysed (n=10)

Excluded from analysis (n=1)

- Missing H-reflex data at the pretx time interval (n=1)

Subjects in Acupuncture (n=9)

Allocated intervention Cryotherapy (n=10)



Allocated intervention Sham (n=10)



Allocated intervention Control (n=10)



Analysed (n=10)


Subjects in Cryotherapy (n=10)

Analysed (n=10)


- Unstable M-responses (n=1)

Subjects in Sham (n=9)

Analysed (n=10)


- Unstable M-responses (n=2)

Subjects in Control (n=8)



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METHODSExperimental designA randomised controlled laboratory study with repeated measures on time was used. Dependent variables were the VM H-refl ex normalised to the M-response (H:M ratio) and pain perception. The independent variables were treatment (acupuncture, cryotherapy, sham treatment and control) and time (baseline: preinjection; pretreatment: 20 min post-injection; post-treatment-0: 50 min post-injection; and post-treatment-20: 70 min post-injection).

SubjectsThirty-six neurologically healthy volunteers (age 22.7±1.79 years, height 1.82±0.08 m, mass 76.72±10.15 kg) with no history of lower extremity conditions resulting in surgery, no lower extremity injury in the past 6 months, and a measurable VM H-refl ex participated in this study. One hundred and twelve subjects were initially recruited in the study. After screening, 72 subjects were excluded due to an unmeasurable VM peak H-refl ex (n=72). After data analyses, an additional four subjects were excluded due to unstable M-responses (n=3) and missing H-refl ex data at the pretreatment time interval (n=1). The CONSORT fl ow chart is presented in fi gure 1. Before participation, all subjects read and signed a written informed consent form approved by the university’s institutional review board.

InstrumentationAnterior knee infusion modelA 20 gauge catheter (Becton Dickinson Medical Systems, Sandy, Utah, USA) was inserted into the lateral aspect of the infrapatellar fat pad on the subject’s dominant limb (fi gure 2). The catheter was inserted directly under the patellar tendon at an angle of 45°, in an inferior-medial direction, with a depth of 1 cm.31 A 100 cm extension tube (B.Braun Medical, Bethlehem, Pennsylvania, USA) was interfaced between the catheter and a 30 ml syringe (Becton Dickinson Medical Systems, Franklin Lakes, New Jersey, USA) fi lled with 5% hypertonic saline (B. Braun, Irvine, California, USA). This syringe was placed on an infusion pump (Graseby Medical Ltd., Hertfordshire, UK) to deliver hypertonic saline constantly over 70 min. The infusion rate was set to 0.12 ml per min with a total vol-ume of 8.5 ml over 70 min.

H-refl ex and M-response (H:M ratio)Subjects remained supine with their involved knee sup-ported at approximately 15° of fl exion and the hip slightly fl exed (fi gure 3).27 Subjects were instructed to place their hands along their sides with their palms facing the ceil-ing. Subjects were also instructed to maintain this posi-tion while they looked at a spot on the ceiling. Subjects listened to white noise through headphones to avoid any possible sound-induced variability in measurements of the H-refl ex.27

Two locations on the testing limb (dominant leg) were shaved, debrided (with sandpaper) and cleaned with alcohol prep wipes before the placement of self-adhesive surface electromyography (EMG) electrodes (silver–silver chloride, 10 mm diameter; EL 503-10; Biopac Systems, Goleta, California, USA). EMG electrodes (2 cm apart) were attached to the bulk of the VM (fi gure 4). The ground electrode was attached to the medial malleolus of the ipsi-lateral limb.

The stimulating module (Biopac STM 100C), isolation adaptor (Biopac STIMISOC) and a bar stimulating elec-trode (Biopac EL 300) provided the stimulus. The inten-sity of the stimulus varied between 100 and 180 V with

Figure 2 Catheter insertion. Figure 3 Subject testing position.



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a duration of 1 ms. The stimulating electrode was placed over the femoral nerve, just lateral to the femoral artery in the femoral triangle of the ipsilateral limb.27 The bar electrode was secured with medical tape and compression warp (fi gure 3).

Surface EMG (MP 150; Biopac Systems, Santa Barbara, California, USA) was used to measure the peak H-refl ex and M-response. Gain was set at 500 to amplify the signal (DA 100B; Biopac Systems) from the electrodes. EMG data were sampled at 2000 Hz for 50 ms. Maximum H-refl ex and M-response were found by gradually increasing the stimu-lator in 0.1–1 V increments, allowing for a 15 s rest interval between stimulations. As the H-refl ex values are extremely variable between subjects, we obtained the M-response to normalise the H-refl ex in each individual.32 33 Once the maxi-mum H and M waves were found, fi ve measurements for each were recorded and used to calculate the H:M ratio. The calculated H:M ratios were then used for data analysis.

Pain perceptionSubjective pain perception was quantifi ed using a 10 cm visual analogue scale (VAS).34

Testing proceduresThe University’s institutional review board approved the testing procedures of this study (fi gure 5). During the

fi rst visit, subjects read and signed the informed consent form approved by the university’s institutional review board. Subjects also read and completed a brief health history form. Subjects were screened for a measurable VM H-refl ex. Subjects with a measurable VM H-refl ex were asked to come back after a week for data collection. Subjects who did not have a measurable H-refl ex were excluded.

On the second visit, baseline (preinjection) VM MNP excitability data were measured. The catheter was inserted into the infrapatellar fad pad. The extension tube linked with the 30 ml syringe loaded with 5% hypertonic saline was connected to the catheter. Twenty minutes after the initial infusion, pretreatment VM MNP excitability data were taken. Each subject was then randomly assigned a treatment (acupuncture, cryotherapy, sham and control) for 30 min. These treatments were administered in a counterbalanced order. Upon completion of the treatment (50 min post-injection), the post-treatment-0 VM MNP excitability data were recorded. Twenty minutes after the treatment, the same data at post-treatment-20 were mea-sured. Pain perception on the VAS was measured before and immediately after the catheter insertion, then every 5 min until catheter removal (70 min post-injection). The catheter was detached after the last measurement. The puncture site for catheter insertion was cleaned and cov-ered with sterilised gauze. Subjects were dismissed when self-reported pain was zero on the VAS.

Treatment groupsAcupuncture (n=9)Acupuncture treatment was performed under direct supervision of a licensed acupuncturist. Acupuncture points (acupuncture needle sites: SP9, SP10, ST36, GB34, and one next to the catheterh—ah shi point;35 table 1 and fi gure 4)36 were cleaned with alcohol prep before and after the treatment. Five disposable sterile stainless steel acu-puncture needles (0.2×43 mm; Dongbang Acupuncture, Sungnam, Korea) were manually inserted into each acu-puncture point,36 followed by bidirectional rotation to elicit needle sensation (de qi). A guide tube (0.5×40 mm) was used to decrease acupuncture-related discomfort.

Figure 5 Testing procedures.

Figure 4 Electrode attachment and acupuncture treatment.



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Each acupuncture needle was inserted to a depth of 1 cm. The acupuncture needles were left in place for 30 min.

Cryotherapy (n=10)Two plastic ice bags (1.5 l of crushed ice) were directly placed on the anterior and posterior surfaces of the knee27 for 30 min. The ice bags were secured with a 4-inch wide compression wrap (fi gure 6).

Sham (n=9)The same methods used for the cryotherapy treatment group were applied, but cat litter (1.5 l) was fi lled in the plastic bag instead of crushed ice.

Control (n=8)Subjects received no treatment. The catheter was inserted. An extension tube was interfaced between the catheter and a 30 ml syringe fi lled with isotonic saline (0.9% sodium chloride). This syringe was placed on the constant infusion pump, but the infusion pump was turned off.

Statistical analysisOur sample size was calculated using an expected change in the H-refl ex of 1.8 and a SD of 1.44.27 Based on these estimations, 11 subjects in each group would be necessary in order to have an 80% chance of detecting a signifi cant difference with p<0.05.

Means were calculated from fi ve trials of each time interval. To test treatment effects over time, a 4×4 mixed model analysis of covariance for the VM MNP excitability (covariate: baseline H:M ratio) was used. A separate 4×16 mixed model analysis of covariance tested the treatment effects for pain perception (covariate: baseline VAS mea-surement). Tukey–Kramer post-hoc tests were used for comparisons (p<0.05 for all tests).

RESULTSMean (SD) perceived AKP as a percentage change from the baseline measurement is depicted in fi gure 7. Continuous infusion of 5% hypertonic saline increased perceived AKP (interaction F42,448=4.58, p<0.001). Fifteen minutes follow-ing the injection, subjects statistically began to feel AKP when the control group to the acupuncture, cryotherapy,

or sham treatment group (p<0.0001). Compared with the control group, perceived AKP was maintained until catheter removal (55 min) in the sham treatment group (p<0.0001).

Mean (SD) VM MNP excitability (H:M ratio) for each treatment over time is summarised in table 2. We did not fi nd any change in VM MNP excitability (H:M ratio) among the four treatment groups (F3,31= 1.68, p<0.19) at any of the time intervals (F2,64=0.66, p<0.52).

Figure 6 Cryotherapy.

Table 1 The acupuncture points, segmental innervations and anatomical locations

PointsSegmental innervations Locations

SP (stomach) 9 (S1–2) In a depression in the angle formed by the medial condyle of the tibia, on the level of the lower border of the tibial tuberosity

SP (spleen) 10 (L2–4) Two cun* above the mediosuperior border of the patellaST (stomach) 36 (L4–5) One fi nger breadth below and lateral to the tibial tuberosityGB (gall bladder) 34 (L5–S1) In the tender depression approximately one cun anterior and inferior to

the head of the fi bulaAh shi point† (L2–4) Medial aspect of infrapatellar fat pad

*Cun, the breadth of the distal phalanx of the thumb.†Ah shi point, a point that is painful on palpation.



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Cryotherapy reduced perceived AKP compared with acupuncture 20 min following application (p=0.0003) and sham treatment 15 min following application (p=0.0006). A reduced pain level in the cryotherapy group was maintained until the last measurement (70 min post-injection, p=0.002). Acupuncture only reduced AKP compared with sham treatment 20 min following applica-tion (p=0.02). At other times, there was no difference in reducing perceived AKP between acupuncture and sham treatment (p=0.98).

DISCUSSIONContinuous infusion of 5% hypertonic saline at a rate of 0.12 ml per min produced constant AKP over a 55 min period. The pain perception in this study peaked at 15 min post-injection and the pain level was maintained until catheter removal (70 min post-injection). A single injection (0.25 ml,7 0.75 ml10 and 1.0 ml8) has previously been used to induce knee pain. The study that used 0.25 ml reported that induced pain peaked within 3 min after the injection, and the pain level was maintained approximately 3–4 min.7 Afterwards, the pain level rapidly reduced to less than two out of 10 in VAS at 10 min post-injection.7 The average pain level in our study was approximately 5 out of 10 as measured by a VAS. This is consistent with a single injection of 5% hypertonic saline (0.25 ml).7 Continuous infusion at a low infusion rate seems to be safe and effec-tive for inducing a moderate level of isolated AKP over a relatively long duration of time. This pain model could be

Table 2 Quadriceps MNP excitability

Acupuncture Cryotherapy Sham Control

Baseline 0.37 (0.27) 0.33 (0.24) 0.30 (0.12) 0.38 (0.23)Pretreatment 0.29 (0.15) 0.30 (0.26) 0.27 (0.17) 0.40 (0.38)Post-treatment-0 0.27 (0.19) 0.27 (0.21) 0.26 (0.15) 0.41 (0.4)Post-treatment-20 0.29 (0.22) 0.26 (0.23) 0.26 (0.12) 0.40 (0.32)

Values are mean (SD).MNP, motoneuron pool.

Figure 7 Pain perception (visual analogue scale) normalised to the baseline measurement for each treatment (tx) over time (±SD).

used to examine neuromechanical changes or to compare different disinhibitory interventions.

Our secondary goal was to examine if AKP is an inde-pendent contributor to quadriceps inhibition. We observed that pain did not change VM MNP excitability, but the direct relationship between AKP and quadriceps inhibi-tion is still uncertain. Knee pain relief by injecting 0.5% bupivicaine in patients with knee osteoarthritis resulted in an increase of voluntary quadriceps activation.5 In contrast, non-steroidal anti-infl ammatory drugs3 or knee arthroscopy6 reduced pain in patients with AKP but did not change quadriceps activation. Recently, induced AKP by 1 ml injection of 5% hypertonic saline into the infra-patellar fad pad caused a decrease in voluntary quadriceps

activation (isometric and isokinetic contraction).8 The infrapatellar fad pad has nociceptive innervations,7 and an increase of nociceptive activity from this structure may affect spinal-mediated refl exes, resulting in quadriceps inhibition. These alterations could include an increase in the fl exion withdrawal response37 38 and/or a decrease in fl exion refl ex thresholds.39 40 For this reason, we expected that our pain model might produce similar effects in the involuntary measurement (VM MNP excitability). Our results support the idea that isolation of nociceptive activ-ity in the infrapatellar fad pad may not directly cause quadriceps inhibition.

Compared with pain, it is relatively well established that knee joint effusion causes quadriceps inhibition.27 41 An increase of Ruffi ni ending activity within the joint cap-sule42 excites the Ib inhibitory interneurons43 in the spinal cord. Ib interneurons receive information from afferents (joint receptors, mechanoreceptors, Golgi tendon organs and some Ia fi bres) and descending signals originating from supraspinal centres (other neurons in the central nervous system).44 A negative, net effect change of the Ib interneu-rons is thought to contribute to quadriceps inhibition.27 It is unlikely, given our fi ndings, that a pain stimulus (types III and IV) facilitates the Ib inhibitory pathway. We specu-late that different types of stimuli may follow different or shared pathways. Based on the available data, spinal-mediated refl exes are more affected by joint effusion and appear to play a bigger role in arthrogenous muscle inhibi-tion than pain. Motor responses from isolated pain and effusion should be compared in future studies.



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Our acupuncture treatment did not produce a signifi -cant effect on VM MNP excitability or pain perception. There have been many studies demonstrating pain reduc-tion; however, multiple sessions of acupuncture treatment may be necessary to generate treatment effects.15 16 20 45 There is a wide variation in the parameters of acupunc-ture treatment for patients with knee pain in terms of the number of acupuncture needles (four,21 45 six,15 nine,16 eight to 1829 and seven to —15),20 the diameter of the acupunc-ture needle,20 and the depth of acupuncture needle inser-tion (1–1.5 cm16 and 0.5–3.5 cm).20 21 In order to minimise the confounding factors between subjects, the acupunc-ture points were set as those commonly used for knee pain (SP9, SP10, ST36, GB 34)15 20 45 using an ah shi point with a depth of 1 cm. The depth of acupuncture needles is commonly decided by the sensation of de qi. De qi is the sensation felt by a patient as a tension and tenderness with acupuncture needle insertions,15 which is believed to be necessary to achieve positive outcomes.45 This may explain why our acupuncture treatment did not show any observable change in the MNP excitability or pain percep-tion, as we used a set protocol with a standard depth.

Application of two ice bags around the knee joint did not change VM MNP excitability. Cryotherapy is thought to be an effective disinhibitory modality due to empirical evidence of cryokinetics and scientifi c demonstrations. An increase in quadriceps activation by knee joint cooling has been reported in the measurement of voluntary (maximal isometric contraction46 and central activation ratio)28 and involuntary activations (H-refl ex).47 In addition, cryother-apy increased quadriceps activation in a healthy popula-tion.28 Therefore, we expected our 30 min cold application would increase the VM MNP excitability under all condi-tions. H-refl ex is a highly variable measurement between subjects (0.93±0.14 in a crossover design study;32 0.32±0.2 in a non-crossover design study).33 To resolve this issue, we normalised the H-refl ex to the M-response. Subjects were nested with treatments in our study. This may have increased variability in VM MNP excitability, failing in the demonstration of signifi cant differences. For this issue, we ended the trial even though we did not have 11 subjects in each group.

The H-refl ex amplitude represents the measurable por-tion of excited MNP and the M-response represents the entire MNP.48 Decreased amplitude of the quadriceps H-refl ex indicates quadriceps inhibition. As subjects have to relax completely in the supine position, this measure-ment allows us to estimate the physiological (involuntary) capacity to recruit available MNP.48 We were interested to

see how an isolated pain stimulus and therapeutic modali-ties change the physiological capacity of MNP excitabil-ity. For this reason, we measured the H-refl ex and the M-response. We excluded 72 subjects due to unmeasur-able quadriceps H-refl ex. The quadriceps H-refl ex is more diffi cult to obtain due to the deeper location of the femoral nerve.27 49 Previous reports also mentioned exclusion of the subjects due to unobtainable H-refl ex in the quadriceps.33

Safety issues related to the anterior knee infusion model should be considered. First, as the 5% hypertonic saline is infused via the catheter and the perceived pain is main-tained for an extended period of time, subjects may feel vasovagal syncope. Vasovagal syncope is from a sudden drop in blood pressure, resulting in light-headedness (faint) due to lack of oxygen supply in the brain.50 In this study, we did not observe any vasovagal reaction. We believe that this was due to the subjects’ testing position—sub-jects were laid on the treatment table during infusion. However, subjects may have vasovagal syncope if the testing procedures require functional movements during infusion. We recommend having subjects lay down and elevate their legs above the heart. Second, subjects’ physi-cal activity should be limited after infusion. We tested the anterior knee infusion model in 41 individuals, including fi ve pilot subjects. We asked the subjects not to partici-pate in any physical activity (more demanding than activi-ties of daily living) for 48 h after the infusion. No subjects reported residual pain or discomfort after the infusion.

CONCLUSIONIn conclusion, our anterior knee infusion pain model increased perceived pain in 5 min post-injection, pain peaked at 15 min post-injection, and the pain level main-tained over a 55 min period after the peak. However, an increased perceived pain did not change VM MNP excit-ability. AKP alone may not directly alter quadriceps func-tion. None of the treatments altered VM MNP excitability. Cryotherapy reduced pain while the acupuncture and sham treatments did not.

Contributors Both corresponding authors and coauthors, JP and JTH, have contrib-uted the following criteria: conception and design, acquisition of data or analysis and interpretation of data, drafting the article or revising it critically for important intellectual content, fi nal approval of the version published.

Acknowledgements The authors would like to thank Sool Kim, licensed acupunctur-ist in the state of Utah, USA, for his instruction and supervision in acupuncture treat-ment. The authors thank Dennis Eggett, PhD, for his guidance in statistical analysis. The authors also thank Adam Squires, David Chinn and Sarah Smith for their assistance in data collection and reduction.

Competing interests None.

Patient consent Obtained.

Ethics approval Ethics approval was granted by the Brigham Young University’s in-stitutional review board.

Provenance and peer review Not commissioned; externally peer reviewed.

REFERENCES 1. O’Reilly SC, Jones A, Muir KR, et al. Quadriceps weakness in knee osteoarthritis: the

effect on pain and disability. Ann Rheum Dis 1998;57:588–94.

2. Hurley MV. The effects of joint damage on muscle function, proprioception and

rehabilitation. Man Ther 1997;2:11–17.

Summary points▶ Clinically, pain reduces muscle excitability and results in

weakness.▶ In this experimental model, hypertonic saline was used to

induce pain.▶ Muscle excitability was not affected.▶ Cryotherapy resulted in the greatest reduction of pain.



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3. Suter E, Herzog W, Souza KD, et al. Inhibition of the quadriceps muscles in patients with

anterior knee pain. J Appl Biomech 1998;14:360–73.

4. Arvidsson I, Eriksson E, Knutsson E, et al. Reduction of pain inhibition on voluntary

muscle activation by epidural analgesia. Orthopedics 1986;9:1415–19.

5. Hassan BS, Doherty SA, Mockett S, et al. Effect of pain reduction on postural sway,

proprioception, and quadriceps strength in subjects with knee osteoarthritis.

Ann Rheum Dis 2002;61:422–8.

6. Suter E, Herzog W, Bray RC. Quadriceps inhibition following arthroscopy in patients with

anterior knee pain. Clin Biomech (Bristol, Avon) 1998;13:314–19.

7. Bennell K, Hodges P, Mellor R, et al. The nature of anterior knee pain following

injection of hypertonic saline into the infrapatellar fat pad. J Orthop Res

2004;22:116–21.

8. Henriksen M, Rosager S, Aaboe J, et al. Experimental knee pain reduces muscle

strength. J Pain 2011;12:460–7.

9. Hodges PW, Mellor R, Crossley K, et al. Pain induced by injection of hypertonic saline

into the infrapatellar fat pad and effect on coordination of the quadriceps muscles.

Arthritis Rheum 2009;61:70–7.

10. Henriksen M, Graven-Nielsen T, Aaboe J, et al. Gait changes in patients with knee

osteoarthritis are replicated by experimental knee pain. Arthritis Care Res (Hoboken)

2010;62:501–9.

11. -Nielsen T, Fenger-Grøn LS, Svensson P, et al. Quantifi cation of deep and superfi cial

sensibility in saline-induced muscle pain – a psychophysical study. Somatosens Mot Res

1998;15:46–53.

12. Graven-Nielsen T, Svensson P, Arendt-Nielsen L. Effects of experimental muscle

pain on muscle activity and co-ordination during static and dynamic motor function.

Electroencephalogr Clin Neurophysiol 1997;105:156–64.

13. Farina D, Arendt-Nielsen L, Merletti R, et al. Effect of experimental muscle pain on

motor unit fi ring rate and conduction velocity. J Neurophysiol 2004;91:1250–9.

14. Jensen R, Gøthesen O, Liseth K, et al. Acupuncture treatment of patellofemoral pain

syndrome. J Altern Complement Med 1999;5:521–7.

15. Näslund J, Näslund UB, Odenbring S, et al. Sensory stimulation (acupuncture) for the

treatment of idiopathic anterior knee pain. J Rehabil Med 2002;34:231–8.

16. Tukmachi E, Jubb R, Dempsey E, et al. The effect of acupuncture on the symptoms of knee

osteoarthritis – an open randomised controlled study. Acupunct Med 2004;22:14–22.

17. Ezzo J, Hadhazy V, Birch S, et al. Acupuncture for osteoarthritis of the knee: a

systematic review. Arthritis Rheum 2001;44:819–25.

18. Kagitani F, Uchida S, Hotta H. Afferent nerve fi bers and acupuncture. Auton Neurosci

2010;157:2–8.

19. Andersson S, Lundeberg T. Acupuncture – from empiricism to science: functional

background to acupuncture effects in pain and disease. Med Hypotheses 1995;45:271–81.

20. Scharf HP, Mansmann U, Streitberger K, et al. Acupuncture and knee osteoarthritis: a

three-armed randomized trial. Ann Intern Med 2006;145:12–20.

21. Hübscher M, Vogt L, Ziebart T, et al. Immediate effects of acupuncture on

strength performance: a randomized, controlled crossover trial. Eur J Appl Physiol

2010;110:353–8.

22. Knight KL, Draper DO. Therapeutic Modalities: The Art and Science. Baltimore,

Maryland: Lippincott Willams & Wilkins, 2008:215–51.

23. Pietrosimone BG, Hertel J, Ingersoll CD. The role of disinhibitory modalities in joint injury

rehabilitation. Athletic Therapy Today 2008;13:2–5.

24. Grant AE. Massage with ice (cryokinetics) in the treatment of painful conditions of the

musculoskeletal system. Arch Phys Med Rehabil 1964;45:233–8.

25. Hayden CA. Cryokinetics in an early treatment program. Phys Ther 1964;44:990–3.

26. Pietrosimone BG, Hart JM, Saliba SA, et al. Immediate effects of transcutaneous

electrical nerve stimulation and focal knee joint cooling on quadriceps activation. Med

Sci Sports Exerc 2009;41:1175–81.

27. Hopkins JT, Ingersoll CD, Krause BA, et al. Effect of knee joint effusion on quadriceps

and soleus motoneuron pool excitability. Med Sci Sports Exerc 2001;33:123–6.

28. Pietrosimone BG, Ingersoll CD. Focal knee joint cooling increases the quadriceps central

activation ratio. J Sports Sci 2009;27:873–9.

29. Wexler I, Mayer RF. Temperature sensitivity of slowly adapting mechanoreceptor.

Brain Res 1973;59:384–8.

30. Kunesch E, Schmidt R, Nordin M, et al. Peripheral neural correlates of cutaneous

anaesthesia induced by skin cooling in man. Acta Physiol Scand 1987;129:247–57.

31. Bennell K, Wee E, Crossley K, et al. Effects of experimentally-induced anterior knee pain

on knee joint position sense in healthy individuals. J Orthop Res 2005;23:46–53.

32. Long BC, Hopkins JT. Superfi cial moist heat’s lack of infl uence on soleus function.

J Sport Rehabil 2009;18:438–47.

33. Huffman DH, Pietrosimone BG, Grindstaff TL, et al. Effects of menthol-based

counterirritant on quadriceps motoneuron-pool excitability. J Sport Rehabil

2010;19:30–40.

34. Bijur PE, Silver W, Gallagher EJ. Reliability of the visual analog scale for measurement of

acute pain. Acad Emerg Med 2001;8:1153–7.

35. Harris RE, Clauw DJ. The use of complementary medical therapies in the management

of myofascial pain disorders. Curr Pain Headache Rep 2002;6:370–4.

36. Lu TW, Wei IP, Liu YH, et al. Immediate effects of acupuncture on gait patterns in

patients with knee osteoarthritis. Chin Med J 2010;123:165–72.

37. Herrero JF, Cervero F. Changes in nociceptive refl ex facilitation during carrageenan-

induced arthritis. Brain Res 1996;717:62–8.

38. Young A, Stokes M, Iles JF. Effects of joint pathology on muscle. Clin Orthop Relat Res

1987;219:21–7.

39. Courtney CA, Lewek MD, Witte PO, et al. Heightened fl exor withdrawal responses in

subjects with knee osteoarthritis. J Pain 2009;10:1242–9.

40. Leroux A, Bélanger M, Boucher JP. Pain effect on monosynaptic and polysynaptic refl ex

inhibition. Arch Phys Med Rehabil 1995;76:576–82.

41. Iles JF, Stokes M, Young A. Refl ex actions of knee joint afferents during contraction of

the human quadriceps. Clin Physiol 1990;10:489–500.

42. Palmieri RM, Tom JA, Edwards JE, et al. Arthrogenic muscle response induced by

an experimental knee joint effusion is mediated by pre- and post-synaptic spinal

mechanisms. J Electromyogr Kinesiol 2004;14:631–40.

43. Harrison PJ, Jankowska E. Sources of input to interneurones mediating group I non-

reciprocal inhibition of motoneurones in the cat. J Physiol (Lond) 1985;361:379–401.

44. Jankowska E, Lundberg A. Interneurones in the spinal cord. Trends Neurosci

1981;4:230–3.

45. Vaghela SA, Donnellan CP. Acupuncture for back pain, knee pain and insomnia in

transverse myelitis – a case report. Acupunct Med 2008;26:188–92.

46. Rice D, McNair PJ, Dalbeth N. Effects of cryotherapy on arthrogenic muscle

inhibition using an experimental model of knee swelling. Arthritis Rheum

2009;61:78–83.

47. Hopkins J, Ingersoll CD, Edwards J, et al. Cryotherapy and transcutaneous electric

neuromuscular stimulation decrease arthrogenic muscle inhibition of the vastus

medialis after knee joint effusion. J Athl Train 2002;37:25–31.

48. Hopkins JT, Ingersoll CD. Arthogenic muscle inhibition: a limiting factor in joint

rehabilitation. J Sport Rehabil 2000;9:135–59.

49. Kameyama O, Hayes KC, Wolfe D. Methodological considerations

contributing to variability of the quadriceps H-refl ex. Am J Phys Med Rehabil

1989;68:277–82.

50. Silverthorn DU. Human Physiology. 4th edn. San Francisco, California: Pearson

Education, 2005:500–9.



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