1. 1
Pulsed electromagnetic field therapy reduces delayed onset muscle
soreness in marathon runners. A double-blind randomized placebo-
controlled study.
1
Christina Haugaard Rasmussen,
1
Michael Skovdal Rathleff,
1
Camilla Rams Knudsen,
1
Søren Thorgaard Skou,
2
Martin
Grønbech Jørgensen,
3
Jens Lykkegaard Olesen,
1
Vesal Khalid,
1
Sten Rasmussen
Affiliations:
1: Orthopeadic Surgery Research Unit, Aalborg Hospital - Aarhus University Hospital, Denmark
2: Department of Geriatrics, Aalborg Hospital - Aarhus University Hospital, Denmark
3: Department of Rheumatology, Aalborg Hospital – Aarhus University Hospital, Denmark
Corresponding author:
Sten Rasmussen
Associate Professor Director of Research
+ 45 99 32 23 67
+ 45 25 52 04 62 (mobile)
sten.rasmussen@rn.dk
AARHUS UNIVERSITY HOSPITAL - AALBORG HOSPITAL
Orthopaedic Surgery Research Unit
Research and Innovation Center
15 Soendre Skovvej
DK-9000 Aalborg
www.orto.rn.dk
Keywords: pain, delayed onset muscle soreness, pulsed electromagnetic field, marathon
18 pages
5 tables (2 demography, daily running, AUC, Vas scores) and 2 figures (Flow diagram, Vas scores)

2. 2
Abstract (150 ord ud af 250 tilladte)
Objective: To investigate the efficacy of pulsed electromagnetic fields (PEMF) in reducing delayed onset muscle
soreness (DOMS) in marathon runners.
Design: Double-blind, randomized, placebo-controlled trial
Methods: 133 marathon runners aged 18 or above were randomly assigned to either PEMF or a placebo device. Both
the active group (n=69) and the placebo group (n=64) were instructed to use the device 20 minutes per session, four
times a day in the five days after a completed marathon. Primary treatment outcome was pain assessed by visual
analog scale (VAS) during a 90° squat three times a day in the five days after the completed marathon. These VAS
scores were then described with area under curve (AUC).
Results: Subjects randomized to active treatment had significantly lower pain than the placebo group with AUC 568
(IQR: 192-1198) and 848 (IQR: 478-2220), p=0.024. (p = 0.024). Conclusion: PEMF reduced DOMS in runners
completing a marathon run.
Nyt Abstract:
Pulsed Electromagnetic Field Therapy (PEMF) is a bioelectromagnetics that induces small electrical currents and has
been shown to reduce pain in different indications. However inconsistencies exist and not all studies are conclusive.
Delayed onset muscle soreness (DOMS) is a frequent phenomenon seen in marathon runners and is a defined acute
sensation of pain and discomfort after strenuous exercise. The objective of this double blind randomized trial was to
investigate the efficacy of PEMF in reducing DOMS in marathon runners. A total of 133 marathon runners aged 18 or
above were randomly assigned to either PEMF or a placebo device. Both the active group (n=69) and the placebo
group (n=64) were instructed to use the device 20 minutes per session, four times a day in the five days after a
completed marathon. Primary treatment outcome was pain assessed by visual analog scale (VAS) during a 90° squat
three times a day in the five days after the completed marathon. These VAS scores were then described with area
under curve (AUC).Subjects randomized to active treatment had significantly lower pain than the placebo group with
AUC 568 (IQR: 192-1198) and 848 (IQR: 478-2220), p=0.024. (p = 0.024). PEMF reduces DOMS in runners completing
a marathon run.

3. 3
1. Introduction ( 309 (med overskrifter) ud af 500 tilladte)
Pulsed Electromagnetic Field Therapy (PEMF) belongs to the field of bioelectromagnetics. It differs from other bio
magnetics because it emits a sub threshold, low-power, low-frequency electromagnetic waveform (1). The PEMF
devices induce small electrical Faraday currents in the tissue because of a constant changing magnetic flux (2). There is
a growing body of clinical evidence that PEMF have analgesic effects on humans. PEMF has also been shown to reduce
pain in patients with osteoarthritis (3,4), rheumatoid arthritis (5,6), diabetic neuropathy (7), fibromyalgia (1,8), distal
radius fractures (9), pelvic pain (10) and postoperative pain (11-13). However inconsistencies exist and not all studies
find a positive effect on pain reduction (2,3,14-16) and some are inconclusive (17,18). However no one has yet
investigated the effect of PEMF on post exercise delayed onset muscle soreness (DOMS).
Delayed onset muscle soreness (DOMS) is a frequent phenomenon seen in marathon runners in the days after
completing a marathon run (19-21). Completing a marathon results in a significant load on the human body.
Physiologic effects of a marathon involves muscular and connective tissue damage which initiates an inflammatory
response as well as release of metabolic factors like lactate and free radicals, intracellular metabolites and by-
products of proteolysisThese are effects proposed to explain DOMS(20,21). DOMS is defined as the sensation of pain
and discomfort in skeletal muscles that occurs after eccentric muscle actions or strenuous exercise. The soreness
increases in intensity in the first 24 to 72 hours after the exercise and remains for up to 5 days. (22-24). DOMS may
delay a speedy return to normal daily living and normal weekly running mileage why a reduction of DOMS are
warranted. The objective of this study is to investigate the efficacy of pulsed electromagnetic field compared with
placebo in reducing DOMS in runners completing a marathon. We hypothesized that PEMF will reduce DOMS in
marathon runners.
2. Methods
2.1 Description of the studied volunteers
Subjects were recruited from three marathons in the summer of 2011; Aabenraa Bjergmarathon, Randers
Flodmarathon and Rold Skov Marathon. Eligibility criteria were age 18 years or more, completed the marathon and
able to speak and read Danish.
We emailed the 439 subjects prior to the marathon to tell them about the project and that we would contact them at
the finish line if they completed the marathon. A total of 94 did not complete the marathon and 212 declined to
participate. At baseline were 133 subjects (114 men and 19 women) were included. The questionnaire was not
returned by 39 subjects and therefore 94 subjects were left for the final data analysis (70,7%) (Figure 1). Baseline
characteristics of participants indicated no differences between the two randomized groups. Characteristics of the 39
participants lost to follow-up were similar to those completing the study (Table 1)
2.2 Intervention
One group received two active PEMF devices and the other group received two sham devices. The subjects were
asked to attach one device to the most painful area on each thigh and activate the devices 20 minutes four times a
day in the five days following the marathon. The pulsed electromagnetic field signal was delivered from a small (2,5
cm diameter, 1 cm thick) battery-powered generator to a single-turn 12-cm-diameter electrical coil. Inside of the
circle and several cms outside the circle a fairly uniform magnetic field of the order 0.1 µTesla normal to
the plane of the loop was established, generated by a current of the order 6 mA. The magnetic field in turn
generates an electric field of the order 1 V/m rotationally symmetric around the axis of the loop. Both fields

4. 4
are largest near the loop, the electric field being zero on the axis (Figure 2).. The device emitted 0.1 ms
wide rectangular bursts with a repetition rate of 1 kHz, and a carrier frequency of 27 MHz. Peak magnetic
field intensity had an effect of 7.3 mW/cm
3
.
2.3 Outcome measurements
The observation period was 5 days starting the first day following the marathon. Self-report questionnaires were given
to all subjects after inclusion. The subjects were told to return the questionnaires in provided post-marked envelopes.
Primary outcome measure was thigh muscle pain measured on a 10 cm visual analog scale during a 90° squat three
times a day; when they woke up, at 12 pm and 8 pm. On the VAS the subjects were asked to draw a line somewhere
between the left extreme (no pain) and the right extreme (worst possible pain). VAS has well accepted clinimetric
properties and has been used to measure DOMS (25-29).
On the day of inclusion height, weight, age, BMI, gender, marathon result and current injuries were recorded. In the
self-report questionnaire subjects were asked about daily activity (minutes); use of PEMF (minutes); use of pain killers
(yes/no). On the fifth day, subjects were asked if they thought they received an active (yes/no/do not know) . On the
sixth day following the marathon all subjects received a mail to thank them for participation and to remind them to
return of the questionnaire. If the questionnaire was not received within one week of this date, participants were
emailed again and telephoned and asked to mail it as quickly as possible. If participant did not send as agreed, they
were once again emailed and called to remind them to send back the questionnaire.
Study participant was told to contact the responsible investigator if they felt side effect that could be attributed to the
use of PEMF.
2.4 Sample size, ethics, randomization and statistical analysis
A pilot study was conducted before the current trial. Based on data from the pilot study we needed 116 runners to
detect a difference of 15mm on a VAS using a standard deviation of 25mm and 90 % power at a 5 % significance level.
Written informed consent was obtained from all participants prior to enrolment. The study was approved by the local
ethics committee (N-20100021), and the Danish Data Protection Agency (2008-58-0028). The study was registered in
Clin Trial Gov ()
All runners were contacted at the finish line of the marathon and asked to participate in the study. After inclusion and
written informed consent the runners were randomly allocated into receiving device A or device B. A six block
randomization procedure stratified into gender was used. The design was a double blind randomized placebo-
controlled trial. A person not involved in the study prepared two batches of PEMF-devices (ActiPatch
TM
, Bioelectronic).
One batch was marked as A and one was marked as B. Only this person was aware of which batch contained active
devices. All personnel in the study and participants remained blinded until all possible self-report questionnaires had
been returned. The sham devices did not differ from the active devices in shape, color or weight. Neither the active
nor the sham devices caused any sensations. To assess if blinding of participants was successful all participant was
asked to state in the questionnaire which group they thought they were assigned to.
Data were analyzed with a per protocol analysis. Intention to treat analysis were not possible since only participants
who completed the entire clinical trial and sent back the questionnaire provided VAS score data to analyses. All
analyses were done using Stata Version 11 and p-values of less than 0.05 were considered significant. Parametric data
was analyzed with un-paired Student t-test and non-parametric data with Fisher’s exact test and Wilcoxon rank-sum
test. Primary outcome was described with the area under a curve (AUC). This area was calculated by addition of two

5. 5
consecutive vas scores divided by the time interval between the two VAS scores. This was done with all 15 VAS scores
for each single participant and addition of the fractions resulted in the AUC. Bang's and James' indexes was used to
asses the success of blinding.
3. Results
3.1. Outcome
The between group difference for the primary outcome of thigh pain during semi-squat during 5 days following the
marathon showed a significantly lower pain among the group receiving an active device compared to the placebo
group AUC 568 (IQR: 192-1198) and 848 (IQR: 478-2220), p=0.024). The secondary outcome showed that the group
receiving active PEMF ran for a significantly longer time on the first day following the marathon (running time 61 min
vs. 27 min, p=0.017), table X.
3.2 Adherence, adverse events and cointerventions.
The mean duration of daily PEMF use during the 5 days following the marathon was 360 minutes in the placebo group
and 320 minutes in the active group (p=0.66). No adverse effects of the PEMF-device were reported during the study.
Use of analgesics was reported by 3/69 in the sham group and 0/64 in the active group.
3.3 Drop out analysis
No significant differences were found between drop outs and the participants who completed the study in terms of
age, gender and marathon time.
3.4 Blinding analysis
A blinding index was calculated from outcome about whether the subjects believed they had received an active
device, a placebo device or did not know. James’ method showed a successful blinding (p=0.997) whereas Bang’s
method showed a successful blinding in the active treated group (p=1.00) and an unsuccessful blinding in the placebo
treated group (p=0.00001)
4. Discussion (2064 ud af 1500 tilladte) nu 1499 ord
The results from this double-blind, randomized, placebo-controlled study, demonstrated that PEMF had a significant
effect on reducing DOMS in marathon runners compared to placebo. Furthermore there was a strong trend towards
subjects receiving the active PEMF-device were more active in the days following the marathon race
This is the first study that has found a positive pain reducing effect of PEMF on DOMS. Earlier research has indicated a
strong analgesic effect of PEMF working through the inflammatory processes, opioid pathways, change in neural and
brain activity and impact on membrane potentials, ion exchange and permeability of cells. Two double-blind, placebo-
controlled, randomized studies found up to 300 percent decrease in pain scores in postoperative breast reduction
patients (12,13). The analgesia was suggested to result from an effect of PEMF on inflammation. Rohde et al. did not
find significant differences for TNF-α, VEGF and FGF-2, but demonstrated that IL-1β levels in the wound exudates of
actively treated patients were significantly reduced. Another study showed disruption of IL-1 signaling reduced wound
fibrosis and scar formation, improved skin architecture and increased tensile strength (32). The results of these
studies showed that PEMF reduced pain and furthermore that PEMF’s reduction of IL-1 both reduced inflammation
and improved tissue regeneration.
Shupak et al suggested that pain reducing effect of PEMF acted through an opioid pathway. First they demonstrated
an analgesic effect of PEMF on mice that were later replicated in a study on humans (33,34). Their work suggested

6. 6
that PEMF did not affect the human perception in general, but increased pain thresholds indicative of an analgesic
response (34). Their work was further supported by other studies which showed that the use of PEMF changed opioid
receptor densities in the brain (35) and that the PEMF effect was mediated by endogenous opioids in the central
nervous system (36,37). The attenuation of PEMF induced analgesia by the opioid antagonist naloxone as well as other
opioid receptor antagonists supported these arguments (38,39). A PEMF study on snails found PEMF to increase
enkephalinase inhibitor and induce opioid analgesia (38). These findings suggested the analgesic effects of PEMF
somehow involved an augmentation of endogenous opioids (1).
Some studies have shown that helmets with PEMF can change brain wave activity, suggesting that the effects of PEMF
are the result of a direct effect on central nervous function (1) Robertson et al. found significant correlations between
the changes in neural activation and field strength for both the anterior cingulated cortex and insula, which are brain
areas involved in pain perception. Increased PEMF strength exposure induces less post-exposure processing of pain
indicating a dose-dependent effect (40). Ryczko et al. suggest PEMF influence the firing patterns of thalamic neurons
to cause analgesia (41).
One of the most popular explanations to explicate the positive effect of electromagnetic fields on the body is their
influence on the membrane potential of body cells. Canapp et al. suggested damaged or diseased cells have an altered
cellular resting membrane potential, which in turn alters the cellular ion exchange and oxygen utilization of the cell.
Altered oxygen utilization has been found in delayed healing tissues and arthritic joints. PEMF stabilized the
membrane potential and improved ion exchange and therefore oxygen utilization according to this article (42). Bachl
et al. have made calculations and do not think it is realistic to affect the membrane potential with a weak
electromagnetic intervention. They think it is more likely that electromagnetic fields interfere with the Ca
2+
signaling
pathway of cells (43). It has also been suggested, but still not proven that PEMF reduces the permeability of cell
membranes and therefore the number of action potentials (2).
Since muscular and connective tissue inflammation is a consequence of a marathon and results in DOMS the analgesic
effect of PEMF working through the inflammatory processes is very plausible to this study. Further PEMF working on
membrane potentials, ion exchange or permeability of cells are all local mechanisms which may be the reason to the
less inflammation at the PEMF site and thus involved in the analgesia of this study.
DOMS was measured on a self-reported pain VAS. Other methods to measure pain are pain threshold assessment and
neurophysiological assessment. These methods would not be feasible on a large scale basis 5 days following the
marathon. VAS is a standard tool in clinical trials to assess the efficacy of analgesic treatments. VAS allows a maximum
sensitivity and comparisons of pain intensities and between-patient scores. It also eliminates the potential bias arising
from memorization of responses given on previous questionnaires, which is often the case with descriptive scales.
The only other study found to investigate the effects of PEMF after physical exercise was a double-blind, randomized,
placebo-controlled study carried out in a laboratory(31). In resemblance with our results they found an accelerated
recovery after physical strain compared to placebo treatment. The physical exercise was a 4 min step test followed by
a 20 min treament with either PEMF or placebo. The PEMF treatment resulted in a more rapid return of the heart rate
to the initial state. They also found that subjects were not able to feel when PEMF was applied as PEMF had no effect
on general feeling of well-being. Likewise a large percentage in both groups thought they had received placebo as they
were not able to feel the current induced by the PEMF device. Most likely this is also the reason why the blinding
appeared unsuccessful in placebo group of this study.
PEMF provides a noninvasive, safe and easy method to treat the site of pain and inflammation and a variety of
diseases and pathologies. Many studies show PEMF is useful in treatment of the musculoskeletal system as well as for
pain relief. Furthermore PEMF is not systemic and not governed by pharmacokinetics. PEMF appears instantaneously
in all compartments of the target tissue where endogenous anti-inflammatory and subsequent tissue repair processes

7. 7
can be modulated (12). Therefore PEMF may accelerate tissue regeneration reduce DOMS and counteract the strong
physiological strain of the marathon. However PEMF could also induce a negative long term effect since PEMF
modulates DOMS and gives the runners the possibility of a speedy return to weekly mileage. One might hypothesize
that PEMF counteracts the human body`s normal response to a marathon run and this could lead to overuse injuries
since the runner is not aware of the body`s normal pain response and continue running when he should be
resting.Though skeletal muscles have a remarkable ability for regeneration and chronic effects of overuse can
therefore probably be ignored {{102 Appell,H.J. 1992}}. The only major contraindications of PEMF are active
hemorrhage and electrical implants. Pregnant patients should also avoid PEMF due to the lack of data (42).
Finally it need to be emphasized that there were no reported side effects with the use of PEMF in either our or any of
the above-mentioned trials (43,46).
The strengths of this study were the rigorous study design and blinding of all personnel and participants. Furthermore
we enrolled a high number of subjects from three yearly marathons. The marathons were not a set up for our study
and the situation with DOMS following a marathon reflects reality.
One of the primary weaknesses were the necessity of making a per protocol analysis instead of a intention to treat
analysis. In addition the completion rate was lower than expected with a drop out rate of 29,3 %. We do not know
how the drop outs would have affected our study if they had completed, but our drop out analysis does not show any
differences between the subjects who completed and the subjects who dropped out. One of the main reasons for the
high percentage of dropout could be that some of the runners did not have enough pain to find the motivation to
complete the self-report questionnaires. These drop outs might be experienced marathon runners, ultra runners and
the runners with fast marathon times since training attenuates pain {{123 Schwane,J.A. 1987}}. To avoid these drop
outs we could have made thresholds for pain, marathon time and number of marathons as inclusion criteria.
This experiment was conducted with PEMF intensity and pulse rate defined by the manufacturer. There is a possibility
that other intensities and pulse rates could have changed the effects (30). There are only a few data available that
discuss the choice of parameters. These data suggest a “window of response” exists within a specific PEMF setting,
and the effect outside this range is negligent. Robertson et al. found increases or decreases in nociceptive sensitivity
with different magnetic field exposure which argue for a specific “window of reponse”(40). This could explain the
apparently conflicting findings in previous studies using different exposure profiles.
Double-blind, randomized, placebo-controlled studies using a variety of PEMF exposure protocols are necessary to
reach any conclusions regarding the potential benefits of PEMF in treatment of pain and to achieve the optimal values
of parameters of magnetic fields. Future research should investigate the effect of PEMF on musculoskeletal disorders
where accelerated tissue regeneration and pain relief is needed.
Conclusion
This double-blind, randomized, placebo-controlled study shows that active PEMF reduce DOMS in runners completing
a marathon. This finding may lead to a quicker recovery after strenuous exercise.

8. 8
Abbreviations
PEMF: Pulsed electromagnetic field
DOMS: Delayed onset muscle soreness
VAS: Visual analogue scale
Conflict of interest
There are no conflicts of interest for any of the authors.
Acknowledgements
The authors sincerely thank Michael Maigaard from ActiPatch
TM
Scandinavia ApS, Randers, Denmark for the generous
donation of the PEMF devices used in this study. Furthermore a deep gratitude to the volunteers who helped to
inform and enroll marathon runners at the running sites: Solvej Videbæk Andersen, Jesper Haugaard Rasmussen,
Tommy Bank Jensen, Anne Kildegaard Hansen, Nikolaj Meldgaard Jensen, Mette Abildgaard Pedersen, Marthe Mari
Ødegård Bjerke, Kristine Bennedsgaard, Hans Hansen and Vesal Khalid.
(1) Thomas AW, Graham K, Prato FS, McKay J, Forster PM, Moulin DE, et al. A randomized, double-blind,
placebo-controlled clinical trial using a low-frequency magnetic field in the treatment of musculoskeletal
chronic pain. Pain Res Manag 2007 Winter;12(4):249-258.
(2) Fernandez MI, Watson PJ, Rowbotham DJ. Effect of pulsed magnetic field therapy on pain reported by
human volunteers in a laboratory model of acute pain. Br J Anaesth 2007 Aug;99(2):266-269.
(3) Vavken P, Arrich F, Schuhfried O, Dorotka R. Effectiveness of pulsed electromagnetic field therapy in the
management of osteoarthritis of the knee: a meta-analysis of randomized controlled trials. J Rehabil Med
2009 May;41(6):406-411.
(4) Fini M, Giavaresi G, Carpi A, Nicolini A, Setti S, Giardino R. Effects of pulsed electromagnetic fields on
articular hyaline cartilage: review of experimental and clinical studies. Biomed Pharmacother 2005
Aug;59(7):388-394.
(5) Shupak NM, McKay JC, Nielson WR, Rollman GB, Prato FS, Thomas AW. Exposure to a specific pulsed
low-frequency magnetic field: a double-blind placebo-controlled study of effects on pain ratings in
rheumatoid arthritis and fibromyalgia patients. Pain Res Manag 2006 Summer;11(2):85-90.

9. 9
(6) Ganesan K, Gengadharan AC, Balachandran C, Manohar BM, Puvanakrishnan R. Low frequency pulsed
electromagnetic field--a viable alternative therapy for arthritis. Indian J Exp Biol 2009 Dec;47(12):939-948.
(7) Graak V, Chaudhary S, Bal BS, Sandhu JS. Evaluation of the efficacy of pulsed electromagnetic field in the
management of patients with diabetic polyneuropathy. Int J Diabetes Dev Ctries 2009 Apr;29(2):56-61.
(8) Sutbeyaz ST, Sezer N, Koseoglu F, Kibar S. Low-frequency pulsed electromagnetic field therapy in
fibromyalgia: a randomized, double-blind, sham-controlled clinical study. Clin J Pain 2009 Oct;25(8):722-
728.
(9) Cheing GL, Wan JW, Kai Lo S. Ice and pulsed electromagnetic field to reduce pain and swelling after
distal radius fractures. J Rehabil Med 2005 Nov;37(6):372-377.
(10) Jorgensen WA, Frome BM, Wallach C. Electrochemical therapy of pelvic pain: effects of pulsed
electromagnetic fields (PEMF) on tissue trauma. Eur J Surg Suppl 1994;(574)(574):83-86.
(11) Zorzi C, Dall'Oca C, Cadossi R, Setti S. Effects of pulsed electromagnetic fields on patients' recovery
after arthroscopic surgery: prospective, randomized and double-blind study. Knee Surg Sports Traumatol
Arthrosc 2007 Jul;15(7):830-834.
(12) Rohde C, Chiang A, Adipoju O, Casper D, Pilla AA. Effects of pulsed electromagnetic fields on
interleukin-1 beta and postoperative pain: a double-blind, placebo-controlled, pilot study in breast
reduction patients. Plast Reconstr Surg 2010 Jun;125(6):1620-1629.
(13) Heden P, Pilla AA. Effects of pulsed electromagnetic fields on postoperative pain: a double-blind
randomized pilot study in breast augmentation patients. Aesthetic Plast Surg 2008 Jul;32(4):660-666.
(14) Ozguclu E, Cetin A, Cetin M, Calp E. Additional effect of pulsed electromagnetic field therapy on knee
osteoarthritis treatment: a randomized, placebo-controlled study. Clin Rheumatol 2010 Aug;29(8):927-931.
(15) Weintraub MI, Herrmann DN, Smith AG, Backonja MM, Cole SP. Pulsed electromagnetic fields to
reduce diabetic neuropathic pain and stimulate neuronal repair: a randomized controlled trial. Arch Phys
Med Rehabil 2009 Jul;90(7):1102-1109.
(16) Wrobel MP, Szymborska-Kajanek A, Wystrychowski G, Biniszkiewicz T, Sieron-Stoltny K, Sieron A, et al.
Impact of low frequency pulsed magnetic fields on pain intensity, quality of life and sleep disturbances in
patients with painful diabetic polyneuropathy. Diabetes Metab 2008 Sep;34(4 Pt 1):349-354.
(17) Kroeling P, Gross A, Goldsmith CH, Burnie SJ, Haines T, Graham N, et al. Electrotherapy for neck pain.
Cochrane Database Syst Rev 2009 Oct 7;(4)(4):CD004251.
(18) Pieber K, Herceg M, Paternostro-Sluga T. Electrotherapy for the treatment of painful diabetic
peripheral neuropathy: a review. J Rehabil Med 2010 Apr;42(4):289-295.
(19) Appell HJ, Soares JM, Duarte JA. Exercise, muscle damage and fatigue. Sports Med 1992 Feb;13(2):108-
115.

10. 10
(20) Desgorces FD, Noirez P. Quantifying continuous exercise using the ratio of work completed to
endurance limit associated with exercise-induced delayed-onset muscle soreness. Percept Mot Skills 2008
Feb;106(1):104-112.
(21) Miles MP, Clarkson PM. Exercise-induced muscle pain, soreness, and cramps. J Sports Med Phys Fitness
1994 Sep;34(3):203-216.
(22) Armstrong RB. Mechanisms of exercise-induced delayed onset muscular soreness: a brief review. Med
Sci Sports Exerc 1984 Dec;16(6):529-538.
(23) Clarkson PM, Nosaka K, Braun B. Muscle function after exercise-induced muscle damage and rapid
adaptation. Med Sci Sports Exerc 1992 May;24(5):512-520.
(24) Cheung K, Hume P, Maxwell L. Delayed onset muscle soreness : treatment strategies and performance
factors. Sports Med 2003;33(2):145-164.
(25) Barlas P, Walsh DM, Baxter GD, Allen JM. Delayed onset muscle soreness: effect of an ischaemic block
upon mechanical allodynia in humans. Pain 2000 Aug;87(2):221-225.
(26) Craig JA, Cunningham MB, Walsh DM, Baxter GD, Allen JM. Lack of effect of transcutaneous electrical
nerve stimulation upon experimentally induced delayed onset muscle soreness in humans. Pain 1996
Oct;67(2-3):285-289.
(27) Frey Law LA, Evans S, Knudtson J, Nus S, Scholl K, Sluka KA. Massage reduces pain perception and
hyperalgesia in experimental muscle pain: a randomized, controlled trial. J Pain 2008 Aug;9(8):714-721.
(28) Slater H, Arendt-Nielsen L, Wright A, Graven-Nielsen T. Sensory and motor effects of experimental
muscle pain in patients with lateral epicondylalgia and controls with delayed onset muscle soreness. Pain
2005 Mar;114(1-2):118-130.
(29) Wakefield E, Holtermann A, Mork PJ. The effect of delayed onset of muscle soreness on habitual
trapezius activity. Eur J Pain 2011 Jul;15(6):577-583.
(30) Bobacz K, Graninger WB, Amoyo L, Smolen JS. Effect of pulsed electromagnetic fields on proteoglycan
biosynthesis of articular cartilage is age dependent. Ann Rheum Dis 2006 Jul;65(7):949-951.
(31) Grote V, Lackner H, Kelz C, Trapp M, Aichinger F, Puff H, et al. Short-term effects of pulsed
electromagnetic fields after physical exercise are dependent on autonomic tone before exposure. Eur J
Appl Physiol 2007 Nov;101(4):495-502.
(32) Gharaee-Kermani M, Phan SH. Role of cytokines and cytokine therapy in wound healing and fibrotic
diseases. Curr Pharm Des 2001 Jul;7(11):1083-1103.
(33) Shupak NM, Hensel JM, Cross-Mellor SK, Kavaliers M, Prato FS, Thomas AW. Analgesic and behavioral
effects of a 100 microT specific pulsed extremely low frequency magnetic field on control and morphine
treated CF-1 mice. Neurosci Lett 2004 Jan 2;354(1):30-33.
(34) Shupak NM, Prato FS, Thomas AW. Human exposure to a specific pulsed magnetic field: effects on
thermal sensory and pain thresholds. Neurosci Lett 2004 Jun 10;363(2):157-162.

11. 11
(35) Zecca L, Mantegazza C, Margonato V, Cerretelli P, Caniatti M, Piva F, et al. Biological effects of
prolonged exposure to ELF electromagnetic fields in rats: III. 50 Hz electromagnetic fields.
Bioelectromagnetics 1998;19(1):57-66.
(36) Lai H, Carino M. Intracerebroventricular injection of mu- and delta-opiate receptor antagonists block
60 Hz magnetic field-induced decreases in cholinergic activity in the frontal cortex and hippocampus of the
rat. Bioelectromagnetics 1998;19(7):432-437.
(37) Lai H, Carino MA, Horita A, Guy AW. Effects of a 60 Hz magnetic field on central cholinergic systems of
the rat. Bioelectromagnetics 1993;14(1):5-15.
(38) Thomas AW, Kavaliers M, Prato FS, Ossenkopp KP. Antinociceptive effects of a pulsed magnetic field in
the land snail, Cepaea nemoralis. Neurosci Lett 1997 Jan 31;222(2):107-110.
(39) Thomas AW, Kavaliers M, Prato FS, Ossenkopp KP. Pulsed magnetic field induced "analgesia" in the
land snail, Cepaea nemoralis, and the effects of mu, delta, and kappa opioid receptor agonists/antagonists.
Peptides 1997;18(5):703-709.
(40) Robertson JA, Juen N, Theberge J, Weller J, Drost DJ, Prato FS, et al. Evidence for a dose-dependent
effect of pulsed magnetic fields on pain processing. Neurosci Lett 2010 Sep 27;482(2):160-162.
(41) Ryczko MC, Persinger MA. Increased analgesia to thermal stimuli in rats after brief exposures to
complex pulsed 1 microTesla magnetic fields. Percept Mot Skills 2002 Oct;95(2):592-598.
(42) Canapp DA. Select modalities. Clin Tech Small Anim Pract 2007 Nov;22(4):160-165.
(43) Bachl N, Ruoff G, Wessner B, Tschan H. Electromagnetic interventions in musculoskeletal disorders.
Clin Sports Med 2008 Jan;27(1):87-105, viii.
(44) Popescu A, LeResche L, Truelove EL, Drangsholt MT. Gender differences in pain modulation by diffuse
noxious inhibitory controls: a systematic review. Pain 2010 Aug;150(2):309-318.
(45) Schwane JA, Williams JS, Sloan JH. Effects of training on delayed muscle soreness and serum creatine
kinase activity after running. Med Sci Sports Exerc 1987 Dec;19(6):584-590.
(46) Wrobel MP, Szymborska-Kajanek A, Wystrychowski G, Biniszkiewicz T, Sieron-Stoltny K, Sieron A, et al.
Impact of low frequency pulsed magnetic fields on pain intensity, quality of life and sleep disturbances in
patients with painful diabetic polyneuropathy. Diabetes Metab 2008 Sep;34(4 Pt 1):349-354.