|Year : 2020 | Volume
| Issue : 1 | Page : 35-42
Beneficial effects of a negative ion patch on eccentric exercise-induced muscle damage, inflammation, and exercise performance in badminton athletes
Chin-Shan Ho1, Mon-Chien Lee1, Chi-Yao Chang1, Wen-Chyuan Chen2, Wen-Ching Huang3
1 Graduate Institute of Sports Science, National Taiwan Sport University, Taoyuan, Taiwan
2 Center for General Education, Chang Gung University of Science and Technology; Department of Otorhinolaryngology, Head and Neck Surgery, Sleep Center, Linkou-Chang Gung Memorial Hospital, Taoyuan, Taiwan
3 Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
|Date of Submission||11-Apr-2019|
|Date of Acceptance||28-Nov-2019|
|Date of Web Publication||7-Feb-2020|
Prof. Wen-Ching Huang
Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, No. 365, Ming-te Road, Peitou District, Taipei City
Prof. Wen-Chyuan Chen
Center for General Education, Chang Gung University of Science and Technology, No. 261, Wenhua 1st Road, Guishan District, Taoyuan City 33301
Source of Support: None, Conflict of Interest: None
Complementary and alternative medicines (CAMs) are widely applied and accepted for therapeutic purposes because of their numerous benefits. Negative ion treatment belongs to one of the critical categories defined by the National Center for CAM, with such treatment capable of air purification and ameliorating emotional disorders (e.g., depression and seasonal affective disorder). Negative ions can be produced naturally and also by a material with activated energy. Exercise-induced muscle damage (EIMD) often occurs due to inadequate warm up, high-intensity exercise, overload, and inappropriate posture, especially for high-intensive competition. Few studies have investigated the effects of negative ion treatment on muscular injury in the sports science field. In the current study, we enrolled badminton athletes and induced muscle damage in them through eccentric exercise in the form of a high-intensity squat program. We evaluated the effects of negative ion patches of different intensities at three points (preexercise, postexercise, and recovery) by analyzing physiological indexes (tumor necrosis factor [TNF]-α, interleukin [IL]-6, IL-10, creatine kinase [CK], and lactate dehydrogenase [LDH] levels) and performing a functional assessment (a countermovement jump [CMJ] test). We found that a high-intensity negative ion patch could significantly reduce the levels of TNF-α, an injury-associated inflammatory cytokine, and related markers (CK and LDH). In addition, muscular overload-caused fatigue could be also ameliorated, as indicated by the functional CMJ test result, and related muscular characteristics (tone and stiffness) could be effectively improved. Thus, the negative ion treatment could effectively improve physiological adaption and muscular fatigue recovery after EIMD in the current study. The negative ion patch treatment can be further integrated into a taping system to synergistically fulfill exercise-induced damage protection and functional elevation. However, the effects of this treatment require further experimental validation.
Keywords: Alternative medicine, countermovement jump, exercise injury, inflammation, negative ion
|How to cite this article:|
Ho CS, Lee MC, Chang CY, Chen WC, Huang WC. Beneficial effects of a negative ion patch on eccentric exercise-induced muscle damage, inflammation, and exercise performance in badminton athletes. Chin J Physiol 2020;63:35-42
|How to cite this URL:|
Ho CS, Lee MC, Chang CY, Chen WC, Huang WC. Beneficial effects of a negative ion patch on eccentric exercise-induced muscle damage, inflammation, and exercise performance in badminton athletes. Chin J Physiol [serial online] 2020 [cited 2020 Jul 7];63:35-42. Available from: http://www.cjphysiology.org/text.asp?2020/63/1/35/277950
| Introduction|| |
Alternative medicine is a term used to describe therapeutic methods and practices that are not accepted by conventional medicine. The use of complementary and alternative medicine (CAM) has rapidly increased due to several benefits of CAM, including its familiarity to patients, use of noninvasive treatment methods, and reputation for causing fewer side effects, as well as the ability of CAM to bring improvements to quality of life, its utility as a health maintenance regime, patient preferences for holistic medical approaches, and the costs of traditional medical treatment. The National Center for CAM, an organization that is not considered a part of the conventional Western medicine establishment, classified CAM into five categories: alternative medical systems, mind–body interventions, biologically based therapies, body-based manipulative methods, and energy therapies. The prevalence of CAM use was surveyed in 15 countries, and estimates of 12-month prevalence of any CAM use showed remarkable stability in Australia and the United States (at approximately 50% and 37%, respectively) for several years. Although, in practice, CAM demonstrates beneficial health-promoting biological activities, scientific evidence for most CAM therapies is still limited. Therefore, any emergence of CAM as a new form of medicine depends on the accumulation of precise scientific evidence.
When a simple or complex molecule possesses more than its normal number of electrons, it becomes a negatively charged atom called a negative ion. Negative ions are electrostatically attracted to airborne particulate matter (PM), such as dust, mold, and other pollutants and potential allergens, because of the negative charge characteristics of negative air ions. In material science, a negative ion can be applied to novel material processing systems, such as for surface modification of micrometer-sized powders and the formation of a metastable material with carbon negative ion beam deposition. Exposure to high-density negative ions was demonstrated to alleviate depression and the atypical symptoms of seasonal affective disorder. In addition, a meta-analysis found an association of negative air ionization with lower depression scores; however, no consistent effect of positive or negative air ionization was found on anxiety, mood, relaxation, and sleep. PM, especially PM2.5, exerts severe deleterious effects on human health. A negative ion electrically charges PM; compared with uncharged PM, electrically charged PM is deposited or precipitated more rapidly under gravity for the purpose of air purification. The versatile neurohormone serotonin, which plays crucial roles in basic life patterns including sleep and mood regulation, could be regulated by negative ion intervention; however, another study reported contrary findings. In addition, one study reported several evidence-based biological benefits of negative ion intervention, including immune regulation, carcinogenesis inhibition, erythrocyte deformability, aerobic metabolism, and antibacterial activity.
Extreme exercise interventions can exert profound physiological effects. Oxidative stress, including the production of reactive oxygen species (ROS) or free radicals, produced by muscular contractions and energy metabolism during exercise can have both positive and negative physiological effects depending on the redox balance. High-intensity or overload exercise programs generally cause exercise-induced muscle damage (EIMD) and result in a marked decline in muscular function during the first 12–72 h after exercise. Intensive endurance exercise also causes ischemia-reperfusion injury and increases oxygen consumption, white blood cell activation, inflammation, and ROS production. Well-regulated inflammation, followed by EIMD, plays crucial roles in muscle repair and regeneration through the involvement of various cell types. In addition, other therapies, including nutritional supplementation, pharmacological strategies, electrical and manual therapies, and exercise, were applied to treat EIMD, but inconsistencies in the dose and frequency of these therapies and other interventions may account for the lack of consensus regarding their efficacy. Additional studies are warranted to determine the most appropriate dose, frequency, and method of intervention to attenuate EIMD without interference of physiological adaption.
Few studies have investigated the effects of negative ions on EIMD from the perspective of alternative medicine. Thus, in this study, we investigated the effects of negative ion patches of different densities on the functional activities of badminton athletes. In addition, we examined inflammatory cytokine levels and performed the countermovement jump (CMJ) test to determine the physiological and functional activities of negative ion patches by clinical study with high-intensity eccentric EIMD.
| Materials and Methods|| |
Negative ion patch
The negative ion patches used in the current study were provided by Yue Cih Technology Co., Ltd. (Kaohsiung, Taiwan). The patches had standard specifications; that is, an area of 180 cm2 (12 cm × 15 cm) with different negative ion intensities, namely 300, 3,000 and 30,000 ions/cm3 (low, medium, and high intensity, respectively). All intensities were verified by SGS Compliance Certification Service Inc. (New Taipei City, Taiwan) before conducting the experiments.
We recruited 38 badminton athletes from National Taiwan Sport University and randomly divided them into four groups for conducting further experiments: A placebo group and low, medium, and high negative ion intensity groups. We enrolled participants who had at least 2 years of badminton training and had not participated in other neuromuscular interventions in the 6 months prior to enrollment in the current study. [Table 1] shows the anthropometric data of the recruited participants. Two weeks before starting the experiments, the participants were prohibited from taking vitamin supplements, minerals, creatine supplements, herbal extracts, antibiotics, and any anti-inflammatory medication to prevent unnecessary interference. The badminton athletes were randomly assigned into control (n = 9), low (n = 9), medium (n = 10), and high (n = 10) dosage groups and the number of gender difference was also indicated in [Table 1]. All the participants were included in the study after obtaining their written informed consent. This study was reviewed and approved by the Institutional Review Board of Fu-Jen University (New Taipei, Taiwan; No. C105126).
|Table 1: Anthropometric data of the enrolled badminton athletes in the indicated treatments|
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A double-blind experimental design was adopted to examine the effects of a negative ion patch on EIMD. The participants were told to maintain their regular lifestyle 24 h before conducting any experiment and asked to avoid performing any strenuous exercise, staying up late, smoking, or consuming coffee and alcoholic beverages. Exercise-induced damage resulted from the maximum eccentric contraction that occurred while performing a squat. The CMJ test, blood sampling, and muscular stiffness test were performed at preexercise, postexercise, and recovery. All participants completed the standardized bout of resistance exercise involving five sets of ten squats at 80% of the one-repetition maximum, and each repetition was required to be finished in 5 s, consisting of 4-s lowering and 1-s raising with modifications. Participants were asked to rest for 3 min between each squat set. Then, the respective patches were applied to the placebo and low-, medium-, and high-dose groups. Experimental procedures are illustrated in [Figure 1].
|Figure 1: Experimental scheme. The functional ability (countermovement jump test) and biochemical indexes were assessed at preexercise, postexercise, and recovery between the eccentric contraction intervention and negative ion patch treatment. The negative ion patches of indicated intensities were directly pasted on the quadriceps femoris muscle for 48 h.|
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Countermovement jump assessment
The CMJ test is a simple, practical, valid, and reliable measure of lower-body power and is associated with the maximal speed, strength, and explosive strength of lower limbs. The participants were asked to stand on a Kistler force platform (9260AA, Kistler Ltd., Switzerland) on both feet and were examined using a frequency of 1000 Hz. They were asked to place their hands besides their hips and stay on the platform throughout the test. Subsequently, they were asked to squat down until their knees were bent at an angle of 90° and then immediately jump vertically as high as possible, landing back on the mat on both feet at the same time. Mean power (MF), peak power (Fpeak), flight time (FT), and rate of force development (30 ms) were immediately recorded during the jumping action. Each participant repeated this experiment three times, and CMJ data were acquired at the indicated points and calibrated according to individual body weight.
Blood was drawn from the participants at preexercise, postexercise, and recovery and collected into collection tubes not containing the anticoagulant ethylenediaminetetraacetic acid and heparin. Inflammation-associated serum cytokines, namely tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10, were analyzed using colorimetric kits (BioLegend, San Diego, CA, USA). Detailed procedures were described in a previous study.
The levels of serum lactate dehydrogenase (LDH) and creatine phosphokinase were examined using an autoanalyzer (Hitachi 7060, Hitachi, Tokyo, Japan) at the indicated time points. The detailed procedures of samples preparation were described in a previous study.
Muscle stiffness test
A handheld MyotonPRO device (MyotonPRO, Myoton Ltd., Tallinn, Estonia) was used to measure the stiffness of the participants' quadriceps femoris muscles. Muscle stiffness (St; N/m) characterizes the resistance of the soft tissue to a contraction or external force and the ability to restore its initial shape. The device provides a consistent preload force of 0.18 N for initial compression on the subcutaneous tissue and then releases a mechanical force of 0.40 N with an additional 15 ms impulse, which induces a damped or decaying natural oscillation of the tissue. Three myotonometric measurements were performed at each tested point. All participants were asked to lie in a horizontal position on comfortable massage tables and maintain a relaxed posture during measurements. They were all assessed by the same operator to prevent interoperator differences and maintain reliability between sessions.
All results were statistically analyzed using SPSS version 18.0 (IBM, Armonk, NY, USA) and tested using repeated-measures analysis of variance (ANOVA) and mixed two-way ANOVA. Values are expressed as means ± standard deviation, and the mean and standard error of each value were calculated using complete raw data and rounded to provide an appropriate numerical representation. A significant difference within and between groups was considered when P < 0.016 (0.05/3). One-way ANOVA was used to determine the average difference between groups at each point. A result was considered to be statistically significant when the probability of a Type I error was <0.05.
| Results|| |
Effect of the patch on cytokine expression
The levels of crucial inflammatory cytokines, namely IL-6 and TNF-α, and the anti-inflammatory cytokine, namely IL-10, were measured at preexercise, postexercise, and recovery to determine the effects of a negative ion patch on exercise-induced changes in cytokine expression. The IL-6 level [Figure 2]a did not exhibit significant difference in the main effect of time (F (2, 64) = 140.8, P < 0.0001) but not in intensity (F (3, 34) = 0.413, P = 0.745). However, the interaction effect was not significant difference (F (6, 64) = 1.939, P = 0.088). No significant difference was observed among the groups at the three points; however, the eccentric contraction protocol exhibited a significant increase in the IL-6 level at postexercise compared with at preexercise in all groups. Similar trends were observed for the IL-10 level [Figure 2]c. The TNF-α level exhibited a significant difference in the main effect of intensity (F (3, 34) = 8.23, P< 0.001) and time (F (2, 64) = 17.66, P< 0.001) [Figure 2]b. The interaction effect of the TNF-α level was also significant (F (6, 64) = 3.07, P = 0.011). Further analysis at the three indicated points revealed a significant difference in the recovery phase (F (3, 34) = 12.31, P < 0.0001). The TNF-α level was significantly lower in the high- and medium-intensity groups than in the placebo and low-intensity groups (P < 0.05), and the TNF-α level did not significantly differ between the high- and medium-intensity groups.
|Figure 2: Inflammatory cytokine levels at the different points. Serum (a) interleukin-6, (b) tumor necrosis factor-α, and (c) interleukin-10 cytokine levels were measured at preexercise, postexercise, and recovery. The same points with different superscript letters (a and b) indicate a significant difference (P < 0.05) between groups. *, indicates a significant difference compared with preexercise (P < 0.016).|
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Effects of the patch on injury-associated markers
The different patches were immediately applied to the participants who finished the eccentric contraction protocol, and their blood was sampled at the three indicated points to determine the effects of the patches on injury-associated markers. The creatine kinase (CK) level exhibited a significant difference in the main effect of intensity (F (3, 34) = 7.65, P < 0.001) and time (F (2, 64) = 21.84, P < 0.0001). Moreover, the interaction effect of the CK level was significant (F (6, 64) = 2.98, P = 0.032). The CK level was significantly higher at the recovery phase than at the preexercise and postexercise points (P < 0.016). A further analysis of the recovery phase showed a significant difference among the groups (F (3, 34) = 10.21, P = 0.002). The CK level was significantly lower in the high- and medium-intensity groups than in the placebo and low-intensity groups (P < 0.05) [Figure 3]a. The LDH level showed a significance difference in the main effect of intensity (F (3, 34) = 6.23, P = 0.021) and time (F (2, 64) = 32.64, P < 0.0001). In addition, the interaction effect of the LDH level was significant (F (6, 64) = 2.18, P = 0.041). The LDH level significantly differed among the groups in the recovery phase, (F (3, 34) = 9.27, P = 0.018), and the LDH level of the high- and medium-intensity groups was significantly lower than that of the placebo and low-intensity groups (P < 0.05) [Figure 3]b.
|Figure 3: Tissue injury–related indexes at the different points. Serum (a) creatine kinase and (b) lactate dehydrogenase levels were measured at preexercise, postexercise, and recovery. The same points with different superscript letters (a and b) indicate a significant difference (P < 0.05) between groups. *, indicates a significant difference compared with preexercise (P < 0.016).|
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Functional assessment by using the countermovement jump test
As shown in [Table 2], the CMJ test was performed three times at preexercise, postexercise, and recovery to investigate the effects of maximum eccentric contraction-induced injury and the benefits of the negative ion patch. The result demonstrated that the maximum eccentric contraction resulted in a functional decrease, possibly caused by muscular fatigue and injury. We found that all the four indexes (30 ms, MF, Fpeak, and FT) were significantly lower at postexercise than at preexercise (P < 0.016), and no significant difference was found in the 30 ms, MF, Fpeak, and FT indexes among the groups at postexercise (F [3, 34] = 0.69, P = 0.566; F [3, 34] = 0.183, P = 0.907; F [3, 34] = 0.019, P = 0.996, and F [3, 34] = 0.067, P = 0.977, respectively) before the application of the negative ion patch. After the application of the negative ion patch, these four functional indexes were significantly improved in the medium- and high-intensity groups at recovery than at postexercise (P < 0.016). In terms of recovery effects, a significant difference was found in the four functional indexes among the groups (F [3, 34] = 5.994, P = 0.002; F [3, 34] = 4.02, P = 0.016; F [3, 34] = 3.26, P = 0.034, and F [3, 34] = 3.96, P = 0.017, respectively). Compared with placebo and the low-intensity treatment, the high-intensity treatment demonstrated significant benefits in terms of improving functional indexes at recovery.
|Table 2: Changes in the functional parameters of the countermovement jump test in each treatment between the eccentric contraction and recovery phase|
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Effects of the negative ion patch on superficial skeletal muscles
Most injuries caused by the overuse of muscles affect performance and are mostly represented by contractures or muscle shortening, characterized by an increase in the tone and stiffness of muscles. As shown in [Table 3], both muscle tone and stiffness significantly increased immediately after the maximum eccentric contraction within the groups (preexercise vs. postexercise). In the recovery phase after the application of the indicated patches, the high-intensity patch could significantly alleviate both tone and stiffness (both P < 0.016) induced by eccentric exercise and help the stiffness index recover back to the preexercise condition for better muscular fitness (P > 0.016); however, this effect was not observed after other treatments (placebo and low- and medium-intensity patches). In the recovery phase, a significant difference in tone and stiffness indexes was found among treatments (F [3, 34] = 3.12, P = 0.039 and F [3, 34] = 2.82, P = 0.044, respectively). The high-intensity treatment could significantly improve both muscular fitness indexes compared with the low-intensity and placebo treatments at the recovery phase (P < 0.05).
|Table 3: Changes in muscle tone (Hz) and stiffness (N/m) in each treatment between the eccentric contraction and recovery phase|
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| Discussion|| |
In the current study, a negative ion was produced using an activated metastable material, and prototypes of negative ion patches were produced to evaluate their biological beneficial effects on EIMD. EIMD induced by the eccentric contraction protocol caused an increase in the levels of inflammatory cytokines (TNF-α, IL-6, and IL-10) and injury markers (CK and LDH), and the findings of the CMJ test also reflected a functional decrease, possibly caused by muscular fatigue and damage. The relatively high intensities of the negative ion patches could effectively ameliorate the inflammatory response and mitigate injury markers. In addition, muscular fitness and functional activities could be maintained and recovered after EIMD stimulation. It would be potential for further application on athlete and sport science field to accelerate the physiological adaption with higher performance.
In studies on strength and conditioning, the vertical jump test can be used to assess an athlete's lower-body power. The vertical jump, an expression of the stretch-shortening cycle, is often used by strength specialists to not only improve exercise performance but also prevent injury related to fatigue. Studies have investigated the relationship of the vertical jump with components of fitness capacities, including speed, maximal strength, agility, explosive power, and anaerobic performance., Badminton requires lower-forelimb power, the ability to quickly change direction, and the ability to rapidly perform arm movements in order to hit the shuttlecock from different positions. Therefore, in this study, we enrolled badminton athletes, induced quadriceps injury in them through the overload eccentric contraction protocol, and assessed functional performance by performing the CMJ test. High-intensity exercise interventions, such as championship competitions and overload exercise programs, often induce physiological fatigue and muscular injury in athletes and consequently reduce their performance., Cooke et al. indicated that a nutritional strategy (creatine supplementation) may enhance muscle force recovery after eccentrically-induced muscle damage. In the current study, we found that a negative ion patch applied immediately after the overload eccentric contraction could significantly maintain muscular fitness by amelioration of injury and inflammation.
From a physiological perspective, studies have demonstrated that intensive exercise can result in muscle tissue damage, ion imbalance, neutrophil infiltration, free radical production, and cytokine excretion and cause an increase in oxidative injury, inflammation, and injury-associated markers (CK and LDH)., Nutritional supplements, such as probiotics and whey protein,, and alternative exercise interventions have been shown to effectively ameliorate intensive exercise-induced tissue injury markers. In addition, acute muscle inflammation is activated by intensive contraction during exercise because of leukocyte infiltration with the expression of inflammatory cytokines, such as TNF-α, IL-6, and IL-10. According to the results of the current study, the application of a negative ion patch, which can be considered an energy therapy, could be an alternative and noninvasive method to beneficially improve inflammatory responses and related tissue injury markers.
Musculoskeletal disorders, such as muscle fatigue and injury, can reflect changes in muscle tone and stiffness. An increase in muscle tone and stiffness can represent the onset of more severe damage and pain, particularly after intensive training. The measurements of tone, tension, and stiffness could effectively identify overload states and significantly reduce the risk of contusion, and these indexes have been measured to monitor athletes exposed to high training loads. An assessment of these indexes showed that alternative methods, such as massage and electrotherapy, could mitigate gastrocnemius muscle fatigue. Consistent with these findings, in the current study, we found that negative ion patches could effectively improve muscle tone and stiffness induced by overload eccentric contraction. The female also demonstrated the lower respiratory exchange ratio, lesser reliance on glycogen utilization, and higher in intramyocellular lipid utilization during endurance exercise as compared to male. The metabolism during endurance exercise were mediated by estrogen and physiological responses could be also different by sex-based differences. However, there were limited studies to address the physiological inflammation induced by high intensity exercise on sex difference. The further study was warranted for validation of negative ions on physiological effects with sex difference.
The Kinesio tape (KT), developed by Dr. Kenso Kase in the 1970s, is an elastic therapeutic tape widely used to treat sports injuries and various other disorders. A meta-analysis reported that limited quality evidence is available to support the use of KT in the management or prevention of sports injuries, but KT may improve strength and range of motion in certain injured cohorts as well as force sense errors. In kendo athletes, taping of the Achilles tendon could not only protect the Achilles tendon from injury but also enhance performance in the kendo striking motion. Application of KT for 72 h in healthy and uninjured male athletes could improve their neuromuscular and kinetic performance during CMJ. Another study investigated the effect of KT on protocol-induced gastrocnemius muscle fatigue and found that KT could not reduce the adverse effect of fatigue on functional activities, such as CMJ. The epidemiology of alternative racquet-sport injury also reported the lower extremities were the most common body region injured (37%). Further analysis, the strains/sprains injury type also demonstrated the most common injury type in the trunk (73%), lower extremities (65%), and upper extremities (32%), especially in youngest player population.
However, we found that the negative ion patch treatment could reduce not only inflammation and injury marker levels [Figure 2] and [Figure 3] but also ameliorate the performance decrease [Table 2] caused by eccentric contraction fatigue. Therefore, we believe that negative ion patch treatment can be further integrated into a taping system to synergistically meet the purposes of injury protection and fatigue recovery based on our preliminary results and material prototypes.
| Conclusions|| |
Exercise is a form of preventive medicine and is beneficial for health promotion. Thus, the number of people who exercise regularly has been increasing, and related products, including sport equipment, assistive devices, and nutritional supplements, are being developed to support the growing market. Based on the findings of the current evidence-based study, the negative ion patch treatment can be a potential option for muscular fatigue recovery and physiological adaption. We also argue that negative ion application can be used as an alternative option for therapeutic/preventive strategies in the field of sports science.
This study was funded by the University-Industry Cooperation Fund, National Taiwan Sport University, Taoyuan, Taiwan (NTSU No.1061028). The authors are grateful to the graduate students at the Sport Nutrition Laboratory, National Taiwan Sport University, for their technical assistance in conducting the clinical human trials. This manuscript was also edited by Wallace Academic Editing.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Suzuki N. Complementary and alternative medicine: A Japanese perspective. Evid Based Complement Alternat Med 2004;1:113-8.
Fan KW. National center for complementary and alternative medicine website J Med Libr Assoc 2005;93:410-2.
Harris PE, Cooper KL, Relton C, Thomas KJ. Prevalence of complementary and alternative medicine (CAM) use by the general population: A systematic review and update. Int J Clin Pract 2012;66:924-39.
Ishikawa J. Negative-ion source applications. Rev Sci Instrum 2008;79:02C506.
Bowers B, Flory R, Ametepe J, Staley L, Patrick A, Carrington H. Controlled trial evaluation of exposure duration to negative air ions for the treatment of seasonal affective disorder. Psychiatry Res 2018;259:7-14.
Perez V, Alexander DD, Bailey WH. Air ions and mood outcomes: A review and meta-analysis. BMC Psychiatry 2013;13:29.
Qiu B, Li Q, Hong W, Xing G. Characterization of the key material for elimination of PM2.5 particles in the atmosphere. J Spectrosc 2015;20:5.
Ryushi T, Kita I, Sakurai T, Yasumatsu M, Isokawa M, Aihara Y, et al
. The effect of exposure to negative air ions on the recovery of physiological responses after moderate endurance exercise. Int J Biometeorol 1998;41:132-6.
Bailey WH, Williams AL, Leonhard MJ. Exposure of laboratory animals to small air ions: A systematic review of biological and behavioral studies. Biomed Eng Online 2018;17:72.
Jiang SY, Ma A, Ramachandran S. Negative air ions and their effects on human health and air quality improvement. Int J Mol Sci 2018;19:E2966.
Kawamura T, Muraoka I. Exercise-induced oxidative stress and the effects of antioxidant intake from a physiological viewpoint. Antioxidants (Basel) 2018;7:E119.
Jamurtas AZ, Theocharis V, Tofas T, Tsiokanos A, Yfanti C, Paschalis V, et al
. Comparison between leg and arm eccentric exercises of the same relative intensity on indices of muscle damage. Eur J Appl Physiol 2005;95:179-85.
Lynn A, Garner S, Nelson N, Simper TN, Hall AC, Ranchordas MK. Effect of bilberry juice on indices of muscle damage and inflammation in runners completing a half-marathon: A randomised, placebo-controlled trial. J Int Soc Sports Nutr 2018;15:22.
Peake JM, Neubauer O, Della Gatta PA, Nosaka K. Muscle damage and inflammation during recovery from exercise. J Appl Physiol (1985) 2017;122:559-70.
Howatson G, van Someren KA. The prevention and treatment of exercise-induced muscle damage. Sports Med 2008;38:483-503.
VanDusseldorp TA, Escobar KA, Johnson KE, Stratton MT, Moriarty T, Cole N, et al
. Effect of branched-chain amino acid supplementation on recovery following acute eccentric exercise. Nutrients 2018;10:E1389.
Huang WC, Wei CC, Huang CC, Chen WL, Huang HY. The beneficial effects of Lactobacillus plantarum
PS128 on high-intensity, exercise-induced oxidative stress, inflammation, and performance in triathletes. Nutrients 2019;11:E353.
Kan NW, Lee MC, Tung YT, Chiu CC, Huang CC, Huang WC. The synergistic effects of resveratrol combined with resistant training on exercise performance and physiological adaption. Nutrients 2018;10:E1360.
Feng YN, Li YP, Liu CL, Zhang ZJ. Assessing the elastic properties of skeletal muscle and tendon using shearwave ultrasound elastography and MyotonPRO. Sci Rep 2018;8:17064.
Marián V, Katarína L, Dávid O, Matúš K, Simon W. Improved maximum strength, vertical jump and sprint performance after 8 weeks of jump squat training with individualized loads. J Sports Sci Med 2016;15:492-500.
Rodacki AL, Fowler NE, Bennett SJ. Vertical jump coordination: Fatigue effects. Med Sci Sports Exerc 2002;34:105-16.
Kenny IC, Ó Cairealláin A, Comyns TM. Validation of an electronic jump mat to assess stretch-shortening cycle function. J Strength Cond Res 2012;26:1601-8.
Çakir-Atabek H. Relationship between anaerobic power, vertical jump and aerobic performance in adolescent track and field athletes. J Phy Edu Sport 2014;14:643.
Hensley LD, Paup DC. A survey of badminton injuries. Br J Sports Med 1979;13:156-60.
Cooper CN, Dabbs NC, Davis J, Sauls NM. Effects of lower-body muscular fatigue on vertical jump and balance performance. J Strength Cond Res 2018. doi: 10.1519/JSC.0000000000002882.
Cooke MB, Rybalka E, Williams AD, Cribb PJ, Hayes A. Creatine supplementation enhances muscle force recovery after eccentrically-induced muscle damage in healthy individuals. J Int Soc Sports Nutr 2009;6:13.
Clifford T, Allerton DM, Brown MA, Harper L, Horsburgh S, Keane KM, et al
. Minimal muscle damage after a marathon and no influence of beetroot juice on inflammation and recovery. Appl Physiol Nutr Metab 2017;42:263-70.
Rodrigues BM, Dantas E, de Salles BF, Miranda H, Koch AJ, Willardson JM, et al
. Creatine kinase and lactate dehydrogenase responses after upper-body resistance exercise with different rest intervals. J Strength Cond Res 2010;24:1657-62.
Huang WC, Chang YC, Chen YM, Hsu YJ, Huang CC, Kan NW, et al
. Whey protein improves marathon-induced injury and exercise performance in elite track runners. Int J Med Sci 2017;14:648-54.
Kang MS, Kim J, Lee J. Effect of different muscle contraction interventions using an isokinetic dynamometer on muscle recovery following muscle injury. J Exerc Rehabil 2018;14:1080-4.
Huang PC, Tsai KL, Chen YW, Lin HT, Hung CH. Exercise combined with ultrasound attenuates neuropathic pain in rats associated with downregulation of IL-6 and TNF-α, but with upregulation of IL-10. Anesth Analg 2017;124:2038-44.
Um GM, Wang JS, Park SE. An analysis on muscle tone of lower limb muscles on flexible flat foot. J Phys Ther Sci 2015;27:3089-92.
McHugh MP, Connolly DA, Eston RG, Kremenic IJ, Nicholas SJ, Gleim GW. The role of passive muscle stiffness in symptoms of exercise-induced muscle damage. Am J Sports Med 1999;27:594-9.
Masi AT, Nair K, Evans T, Ghandour Y. Clinical, biomechanical, and physiological translational interpretations of human resting myofascial tone or tension. Int J Ther Massage Bodywork 2010;3:16-28.
Mroczek D, Superlak E, Konefal M, Mackala K, Chmura P, Seweryniak T; J the Thigh the Right Six Plyometric Volleyball CC. Changes in the stiffness of thigh muscles in the left and right limbs during six weeks of plyometric training in volleyball players. Po J Sport Tour 2018;25:20-4.
Wang JS. Therapeutic effects of massage and electrotherapy on muscle tone, stiffness and muscle contraction following gastrocnemius muscle fatigue. J Phys Ther Sci 2017;29:144-7.
Devries MC. Sex-based differences in endurance exercise muscle metabolism: Impact on exercise and nutritional strategies to optimize health and performance in women. Exp Physiol 2016;101:243-9.
Williams S, Whatman C, Hume PA, Sheerin K. Kinesio taping in treatment and prevention of sports injuries: A meta-analysis of the evidence for its effectiveness. Sports Med 2012;42:153-64.
Tsai FH, Chu IH, Huang CH, Liang JM, Wu JH, Wu WL. Effects of taping on Achilles tendon protection and kendo performance. J Sport Rehabil 2018;27:157-64.
Mendez-Rebolledo G, Ramirez-Campillo R, Guzman-Muñoz E, Gatica-Rojas V, Dabanch-Santis A, Diaz-Valenzuela F. Short-term effects of kinesio taping on muscle recruitment order during a vertical jump: A pilot study. J Sport Rehabil 2018;27:319-26.
Boozari S, Sanjari MA, Amiri A, Ebrahimi Takamjani I. Effect of gastrocnemius kinesio taping on countermovement jump performance and vertical stiffness following muscle fatigue. J Sport Rehabil 2018;27:306-11.
Nhan DT, Klyce W, Lee RJ. Epidemiological patterns of alternative racquet-sport injuries in the United States, 1997-2016. Orthop J Sports Med 2018;6:2325967118786237.
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]