Exercise-induced Muscle Pain Research Articles

Low-load Resistance Exercise with Perceptually Primed Practical Blood Flow Restriction Induces Similar Motor Performance Fatigue, Physiological Changes, and Perceptual Responses Compared to Traditional Blood Flow Restriction in Males and Females.

In the recent past, practical blood flow restriction (pBFR) using non-pneumatic, usually elastic cuffs has been established as a cost-effective alternative to traditional blood flow restriction (BFR) using pneumatic cuffs, especially for training in large groups. This study investigated whether low-load resistance exercise with perceptually primed pBFR using an elastic knee wrap is suitable to induce similar motor performance fatigue as well as physiological and perceptual responses compared to traditional BFR using a pneumatic nylon cuff in males and females. In a randomized, counterbalanced cross-over study, 30 healthy subjects performed 4 sets (30-15-15-15 repetitions) of unilateral knee extensions at 20% of their one-repetition-maximum. In the pBFR condition, each individual was perceptually primed to a BFR pressure corresponding to 60% of their arterial occlusion pressure. Before and after exercise, maximal voluntary torque, maximal muscle activity, and cuff pressure-induced discomfort were assessed. Moreover, physiological (i.e., muscle activity, muscle oxygenation) and perceptual responses (i.e., effort and exercise-induced leg muscle pain) were recorded during exercise. Moderate correlations with no differences between pBFR and BFR were found regarding the decline in maximal voluntary torque and maximal muscle activity. Furthermore, no to very strong correlations between conditions, with no differences, were observed for muscle activity, muscle oxygenation, and perceptual responses during exercise sets. However, cuff pressure-induced discomfort was lower in the pBFR compared to the BFR condition. These results indicate that low-load resistance exercise combined with perceptually primed pBFR is a convenient and less discomfort inducing alternative to traditional BFR. This is especially relevant for BFR training with people who have a low cuff-induced discomfort tolerance.

ASIC3 plays a protective role in delayed-onset muscle soreness (DOMS) through muscle acid sensation during exercise.

Immediate exercise-induced pain (IEIP) and DOMS are two types of exercise-induced muscle pain and can act as barriers to exercise. The burning sensation of IEIP occurs during and immediately after intensive exercise, whereas the soreness of DOMS occurs later. Acid-sensing ion channels (ASICs) within muscle afferents are activated by H+ and other chemicals and have been shown to play a role in various chronic muscle pain conditions. Here, we further defined the role of ASICs in IEIP, and also tested if ASIC3 is required for DOMS. After undergoing exhaustive treadmill exercise, exercise-induced muscle pain was assessed in wild-type (WT) and ASIC3-/- mice at baseline via muscle withdrawal threshold (MWT), immediately, and 24 h after exercise. Locomotor movement, grip strength, and repeat exercise performance were tested at baseline and 24 h after exercise to evaluate DOMS. We found that ASIC3-/- had similar baseline muscle pain, locomotor activity, grip strength, and exercise performance as WT mice. WT showed diminished MWT immediately after exercise indicating they developed IEIP, but ASIC3-/- mice did not. At 24 h after baseline exercise, both ASIC3-/- and WT had similarly lower MWT and grip strength, however, ASIC3-/- displayed significantly lower locomotor activity and repeat exercise performance at 24 h time points compared to WT. In addition, ASIC3-/- mice had higher muscle injury as measured by serum lactate dehydrogenase and creatine kinase levels at 24 h after exercise. These results show that ASIC3 is required for IEIP, but not DOMS, and in fact might play a protective role to prevent muscle injury associated with strenuous exercise.

Role Of Physical Activity In Relationship Between Exercise-induced Muscle Pain And Fibromyalgia Symptom Severity

Role Of Physical Activity In Relationship Between Exercise-induced Muscle Pain And Fibromyalgia Symptom Severity

The Effect of Amiloride (10mg) on the Blood Pressure Response to Ischemic Exercise: Preliminary Observations

BackgroundDuring exercise, blood pressure increases via augmented central command and stimulation of mechano‐ and metabosensitive muscle afferents (i.e., the exercise pressor reflex). Recent evidence has reported a strong role of acid sensing ion channels (ASIC’s) in mediating this reflex, as well as exercise induced muscle pain. Therefore, it is logical to suspect that inhibiting ASIC’s would mitigate the exaggerated blood pressure responses and exercise related muscle pain observed in individuals with peripheral artery disease (PAD).Purpose. We tested the hypothesis that a single 10mg dose of amiloride (a K+‐sparing diuretic known to inhibit ASIC’s) would attenuate the pressor response to blood flow restricted (BFR) plantar flexion exercise in young healthy adults.MethodsSix healthy subjects (5 male, 26 ± 2 y/o, 180.8 ± 12.1 cm, 79.7 ± 12.9 Kg) completed three separate visits. Each visit included two bouts of isometric plantar flexion, both performed until failure at 30% of the predetermined maximal voluntary isometric contraction. During one bout, blood flow to the limb was restricted via a pressurized cuff placed around the proximal portion of the lower leg (BFR); the other bout was performed under free flow conditions. In the first visit, subjects performed these two exercise bouts (in random order) under normal, non‐treated conditions. In the second and third visits, subjects performed these exercise bouts (same order as in visit 1) ~3 hrs after oral ingestion of 10mg of amiloride, or ingestion of a placebo (random order). Blood pressure and heart rate were continuously recorded throughout exercise, and time to fatigue and muscle pain (on a 12cm visual analog scale) was recorded at the end of each exercise bout. Only data from the placebo and amiloride conditions are presented here.ResultsThe addition of BFR reduced total exercise time by ~40.8% (t=2.99, p=0.03), but had no significant effect on peak muscle pain (p>0.10). Due to the preliminary nature of these data, no significant main effects of treatment (amiloride vs. placebo) were observed for free flow or BFR exercise (all p>0.05). However, we did observe a net decrease in the average heart rate response (+10.7 ± 3.0 bpm vs. +11.3 ± 3.7 bpm, ηp2=0.539, p>0.47), the total blood pressure response (5477.5 ± 373.7 mmHg*sec vs. 5841.3 ± 518.9 mmHg*sec, ηp2=0.250, p>0.30), the total time‐tension index (595.9 ± 406.5 Kg*sec vs. 691.6 ± 394.2 Kg*sec, ηp2=0.211, p>0.30), and the blood pressure to time‐tension index relationship (9.09 ± 4.40 mmHg/Kg vs. 11.38 ± 6.30 mmHg/Kg, ηp2=0.08, p>0.50) in the amiloride condition compared to the placebo condition during BFR exercise.ConclusionsWhile these preliminary findings do not indicate significant effects of treatment, these observations serve as strong pilot data to support the continued investigation of amiloride as a method of attenuating the pressor response to ischemic exercise.

The Effects of Self-Myofascial Release Before Weight Training on Functional Movement and Delayed-Onset Muscle Soreness

PURPOSE: This study aimed to examine the effect of the self-myofascial release technique conducted before weight training on functional movement and delayed onset muscle soreness (DOMS).METHODS: The study subjects were divided into three groups: a control group (CON, n=8), an active stretching group (DS, n=8), and a self-myofascial release group (SMR, n=8). All three groups performed the same leg press exercise program for 30 minutes, twice a week for eight weeks. Active stretching and self-myofascial release techniques were conducted before exercise for 30 minutes. Body composition, 1RM, and functional movement screen (FMS) were tested before the 1st-week exercise and after the 4th- and 8th-week exercise training. The DOMS levels were assessed immediately after exercise and at 24, 48, and 72 hours post-exercise using the visual analog scale (VAS).RESULTS: Body weight and body fat percentage showed a significant decrease (p<0.01), and muscle mass and 1RM increased with the exercise period (p<0.01). The FMS score differed between the groups (p<0.05), periods (p<0.01), and groups×periods (p<0.01). The FMS score was significantly higher in the SMR than in the CON group at the 4th- and 8th-week exercise. The exercise-induced VAS level peaked at 48 hours post-exercise in all groups and significantly decreased at 72 hours post-exercise in the SMR group.CONCLUSIONS: These results indicate that self-myofascial release positively affects functional movements and effectively alleviates exercise-induced pain levels. Therefore, self-myofascial release techniques could be used as an effective warm-up strategy to improve physical function and relieve exercise-induced injury and muscle pain.

MLIP causes recessive myopathy with rhabdomyolysis, myalgia and baseline elevated serum creatine kinase.

Striated muscle needs to maintain cellular homeostasis in adaptation to increases in physiological and metabolic demands. Failure to do so can result in rhabdomyolysis. The identification of novel genetic conditions associated with rhabdomyolysis helps to shed light on hitherto unrecognized homeostatic mechanisms. Here we report seven individuals in six families from different ethnic backgrounds with biallelic variants in MLIP, which encodes the muscular lamin A/C-interacting protein, MLIP. Patients presented with a consistent phenotype characterized by mild muscle weakness, exercise-induced muscle pain, variable susceptibility to episodes of rhabdomyolysis, and persistent basal elevated serum creatine kinase levels. The biallelic truncating variants were predicted to result in disruption of the nuclear localizing signal of MLIP. Additionally, reduced overall RNA expression levels of the predominant MLIP isoform were observed in patients' skeletal muscle. Collectively, our data increase the understanding of the genetic landscape of rhabdomyolysis to now include MLIP as a novel disease gene in humans and solidifies MLIP's role in normal and diseased skeletal muscle homeostasis.

Relationship between exercise-induced muscle soreness, pain thresholds, and skin temperature in men and women.

Infrared thermography (IRT) has gained popularity in sports medicine for determining whether changes in skin temperature relate to pain and muscle damage. Such a relationship would support IRT as a non-invasive method to monitor these physiological responses. However, the literature remains controversial. Here, we determine the relationship between exercise-induced muscle soreness (DOMS), pain, and skin temperature in men and women before and after exercise. Twenty-two physically active adults (10 men and 12 women) completed a squat exercise protocol to induce muscle damage. Skin temperature, DOMS, and pressure pain threshold (PPT) were assessed in the quadriceps pre, post-exercise, and 48h post-exercise. DOMS increased similarly in men and women post-exercise and 48h post-exercise. PPT was lower in women compared to men. PPT decreased 48h post-exercise for men but did not differ between the moments for women. Skin temperature responses were sex-dependent. Mean and maximum temperatures increased post-exercise for men, and maximum temperature reduced 48h post-exercise. In women, the minimum temperature increased 48h post-exercise. DOMS was not predicted by skin temperature but showed a direct association between pre and 48h post-exercise variation of maximum skin temperature and PPT. We conclude that there is a sex-dependent effect in analyzing skin temperature changes in response to exercise, something that seems to not have been addressed in previous studies. To date, inferences are generally assumed as similar for both men and women, which we show may not be the case.

ASICs are Required for Immediate Exercise-Induced Muscle Pain (IEIP), but not Delayed Onset Muscle Soreness (DOMS)

IEIP and DOMS are two types of muscle pain induced by exercise. IEIP occurs during whereas DOMS appears days after exercise. Acid sensing ion channels (ASICs) expressed in muscle afferents, play a role in different pain conditions. ASICs are regulated via chemicals released during intense muscle contraction and microinjuries. Recently, we showed that ASICs are required for IEIP. Here, we tested if ASICs are also required for DOMS. Wild type (WT) and ASIC3-/- mice were divided into control and exercise groups. Exercise group underwent an exhaustive exercise; control group were placed on a non-moving treadmill. Locomotor movement was measured via Open field test to examine fatigue and/or soreness immediately and 24h after exercise. Next, exercise-induced muscle pain was assessed by muscle withdrawal threshold (MWT) at baseline, immediately and 24h after exercise. Our results showed; ASIC3-/- had similar baseline locomotor activity, muscle pain responses and exercise performance as WT. However, ASIC3-/- showed different responses after exercise compared to WT. WT had a lower MWT immediately and 24h after exercise compared to baseline. On the other hand, ASIC3-/- showed a lower MWT only 24h after exercise, but not immediately after. In addition, ASIC3-/- had significant lower locomotor activity than WT immediately after exercise. Also, ASIC3-/- had significant lower movement 24h after exercise compared to control ASIC3-/-, however this difference was not significant for WT mice. In summary, while WT and ASIC3-/- had a same exercise performance, they had different pain perception and fatigue immediately, but not 24h after exercise. Unlike WT, ASIC3-/- did not develop IEIP, even though ASIC3-/- had a higher fatigue level than WT as measured by diminished locomotion after exercise. On the other hand, ASIC3-/- developed DOMS a day after exercise like WT. These results show ASICs are required for immediate exercise-induced pain, but not exercise-induced fatigue and DOMS. Supported by the Department of Veterans Affairs Merit Award (5I01BX000776).

ASICs are required for immediate exercise‐induced muscle pain (IEIP), but not delayed‐onset muscle soreness (DOMS)

Introduction IEIP and DOMS are types of muscle pain induced by exercise. IEIP occurs during and immediately after, whereas DOMS occurs days after exercise, and are attributed to metabolites and inflammation in muscle, respectively. Acid sensing ion channels (ASICs), H+-gated channels expressed in muscle afferents, play a role in different pain conditions. ASICs are activated by H+ and other chemicals released during intense muscle contraction and microinjuries. Recently, we showed that ASICs are required for IEIP. PURPOSE Here, we tested if ASICs are also required for DOMS. METHODS C57BL/6 wild type (WT) and ASIC3-/- mice underwent an exhaustive exercise (exercise groups), or were placed on a non-moving treadmill for a same amount of time (control groups). Exercise-induced muscle pain was assessed by muscle withdrawal threshold (MWT) at baseline, immediately and 24h after exercise. Locomotor movement, grip strength and exercise performance were tested at baseline and 24hrs after exercise for WT and ASIC3-/- to evaluate DOMS. RESULTS ASIC3-/- had similar baseline muscle pain, locomotor activity, grip strength, and exercise performance as WT mice. WT showed diminished MWT immediately after exercise indicated they developed IEIP (P < 0.001), but ASIC3-/- mice did not. However, both, ASIC3-/- and WT had similarly lower MWT (P < 0.05) and grip strength (P < 0.01) 24hrs after baseline-exercise. On the other hand, ASIC3-/- displayed significantly lower locomotor activity and repeat exercise performance at 24h timepoint compared to WT mice­ (P < 0.05). CONCLUSION While WT and ASIC3-/- had a same exercise performance, they had different pain perception immediately after, but not a day after exercise. Unlike WT mice, ASIC3-/- did not develop IEIP. At 24h after exercise, ASIC3-/- developed similar DOMS features (hyperalgesia and lower strength) as WT mice. Interestingly, ASIC3 -/- mice had diminished locomotor movement and repeat exercise performance at 24h. These results show ASICs are required for IEIP, but not DOMS, and they might play a protective role from muscle injury during metabolic perturbations like high intensity exercise.

Comparison of murine behavioural and physiological responses after forced exercise by electrical shock versus manual prodding.

What is the central question of this study? Forced treadmill exercise using electrical shock is the most common technique in rodent exercise studies. Here, we examined how the use of electrical shock during forced treadmill exercise affects behavioural and physiological responses in comparison to a novel non-electrical shock technique. What is the main finding and its importance? In comparison to mice that underwent traditional treadmill running induced by electrical shock, mice that underwent forced running using a novel technique involving gentle prodding to induce running showed: (i) higher locomotor activity; (ii) less anxiety-like behaviour; and (iii) altered exercise-induced muscle pain immediately after exercise. Animal models of exercise have been useful to understand underlying cellular and molecular mechanisms. Many studies have used methods of exercise that are unduly stressful (e.g., electrical shock to force running), potentially skewing results. Here, we compared physiological and behavioural responses of mice after exercise induced using a prodding technique that avoids electrical shock versus a traditional protocol using electrical shock. We found that exercise performance was similar for both techniques; however, the shock group demonstrated significantly lower locomotor activity and higher anxiety-like behaviour. We also observed divergent effects on muscle pain; the prodding group showed hyperalgesia immediately after exercise, whereas the shock group showed hypoalgesia. Corticosterone concentrations were elevated to a similar extent for both groups. In conclusion, mice that were exercised without shock generated similar maximal exercise performance, but postexercise these mice showed an increase in locomotor activity, less anxiety-like behaviour and altered muscle pain in comparison to mice that exercised with shock. Our data suggest that running of mice without the use of electrical shock is potentially less stressful and might be a better technique to study the physiological and behavioural responses to exercise.

Effect of Post-Exercise Yoga Poses on Eccentric Exercise-Induced Muscle Soreness, Pain, and Activities of Daily Living

The eccentric (ECC) exercises are an efficient way to exercise the muscles than concentric exercises. However, unaccustomed ECC may cause muscle damage, pain, delayed onset muscle soreness (DOMS) that may lead to temporary functional impairments. The aim is to measure the effects of performed yoga poses after various intensities of ECC exercise protocol with different ranges of motion (ROM) at the elbow and knee. Thirty-six participants aged between 18 and 30 years performed yoga after the ECC protocols (weeks 3, 5, 7, 9) and the ECC protocols without yoga poses (weeks 2, 4, 6, 8) on the elbow and knee muscles (5 × 10 repetitions each session) using their 25%/35% of maximal voluntary isometric contraction (MVIC). The subjective and objective assessments were carried out (activities of daily living (ADL), pain (visual analog scale (VAS), pain pressure threshold (PPT), and MVIC). The FROM ECC exercise with 35% of MVIC without yoga showed moderate pain (0-3.5) in ADL, VAS, and PPT for elbow extensors and showed a statistically significant difference (p ≤ 0.05) compared to the PROM ECC exercise with 25% of MVIC without yoga. ECC exercise performed with 35% of MVIC without yoga induced a higher degree of DOMS, pain, ADL limitations than 25% of MVIC without yoga. Yoga after PROM ECC protocol showed less pain, DOMS in VAS, and PPT for elbow flexors, knee flexors, and knee extensors. The overall percentage of increased MVIC value at the end of the study was between 30.53 and 43.12%. The upper extremity (extensors) muscles are more prone to DOMS and pain when compared to the lower extremity muscles. Performing yoga stretching poses after the eccentric exercise protocol may affect reducing DOMS and muscle pain.

Effect of Large Versus Small Range of Motion in the Various Intensities of Eccentric Exercise-Induced Muscle Pain and Strength

Effect of Large Versus Small Range of Motion in the Various Intensities of Eccentric Exercise-Induced Muscle Pain and Strength

A Comparison of the Effect of Massage With Lavender Gel and Piroxicam Gel on Exercise-induced Muscle Soreness in Male Students of Gonabad University of Medical Sciences

Aims: Muscular pain is a common complication of physical activity. The purpose of this study was to compare the effect of massage with lavender gel and piroxicam gel on exercise-induced muscle pain in male students of Gonabad University of Medical Sciences. Methods &amp; Materials: This semi-experimental study was performed on 75 male students of Gonabad University of Medical Sciences in 2018. The Samples were randomly divided into three groups of 25, including a lavender gel massage group, a piroxicam gel massage group, and a placebo gel massage group. The specimens were randomly divided into three groups of 25, including a lavender gel massage group, a piroxicam gel massage group, and a placebo gel massage group. The training program lasted for 45 minutes, including 10 minutes of warming up and doing stretching exercises, 30 minutes of exercises and the main exercises and 5 minutes for cooling. The research instrument was a checklist for the demographic characteristics of the samples and the Thalog malformation questionnaire. Samples completed the Thalog pain questionnaire after completing the exercise and also after the massage. The Mean±SD were used for descriptive statistics. Normaly distributed data were analyticaly analyzed by paired t-test and ANOVA and non-normaly distributed data were analyticaly analyzed by Wilcoxon and Kruskal-Wallis tests. Findings: The results showed that muscle pain induced by exercise in all three groups after massage was significantly reduced compared to before massage (P&lt;0.001). The results of Kruskal-Wallis test showed that the difference in muscle pain before and after massage with the three gels used (P=0.002) was statistically significant. Massage with lavender gel compared to piroxicam and placebo groups was able to reduce more the muscle pain. Conclusion: Massage with lavender gel compared to the piroxicam gel and placebo gel can be a better way to reduce muscle pain after exercise.

ASICs are required for immediate exercise-induced muscle pain and are downregulated in sensory neurons by exercise training.

Exercise training is an effective therapy for many pain-related conditions, and trained athletes have lower pain perception compared with unconditioned people. Some painful conditions, including strenuous exercise, are associated with elevated levels of protons, metabolites, and inflammatory factors, which may activate receptors and/or ion channels, including acid-sensing ion channels (ASICs), on nociceptive sensory neurons. We hypothesized that ASICs are required for immediate exercise-induced muscle pain (IEIP) and that exercise training diminishes IEIP by modulating ASICs within muscle afferents. We found high-intensity interval training (HIIT) reduced IEIP in C57BL/6 mice and diminished ASIC mRNA levels in lumber dorsal root ganglia, and this downregulation of ASICs correlated with improved exercise capacity. Additionally, we found that ASIC3 -/- mice did not develop IEIP; however, the exercise capacity of ASIC3 -/- was similar to wild-type mice. These results suggest that ASICs are required for IEIP and that diminishment of IEIP after exercise training correlates with downregulation of ASICs in sensory neurons.NEW & NOTEWORTHY Exercise performance can be limited by the sensations of muscle fatigue and pain transmitted by muscle afferents. It has been proposed that exercise training abrogates these negative feedback signals. We found that acid-sensing ion channels (ASICs) are required for immediate exercise-induced muscle pain (IEIP). Moreover, exercise training prevented IEIP and was correlated with downregulation of ASICs in sensory neurons.

Multivariable Recovery After Exercise-induced Muscle Pain in the Forearm Muscles

Multivariable Recovery After Exercise-induced Muscle Pain in the Forearm Muscles

Unpredictable stress delays recovery from exercise-induced muscle pain: contribution of the sympathoadrenal axis

Introduction:Although stress is a well-establish risk factor for the development of chronic musculoskeletal pain, the underlying mechanisms, specifically the contribution of neuroendocrine stress axes, remain poorly understood.Objective:To evaluate the hypothesis that psychological stress-induced activation of the sympathoadrenal stress axis prolongs the muscle pain observed after strenuous exercise.Methods:Adult male Sprague-Dawley rats were exposed to unpredictable sound stress and eccentric exercise. The involvement of the sympathoadrenal stress axis was evaluated by means of surgical interventions, systemic administration of epinephrine, and intrathecal β2-adrenergic receptor antisense.Results:Although sound stress alone did not modify nociceptive threshold, it prolonged eccentric exercise-induced mechanical hyperalgesia. Adrenal medullectomy (ADMdX) attenuated, and administration of stress levels of epinephrine to ADMdX rats mimicked this effect of sound stress. Knockdown of β2-adrenergic receptors by intrathecal antisense also attenuated sound stress-induced prolongation of eccentric exercise-induced hyperalgesia.Conclusion:Together, these results indicate that sympathoadrenal activation, by unpredictable sound stress, disrupts the capacity of nociceptors to sense recovery from eccentric exercise, leading to the prolongation of muscle hyperalgesia. This prolonged recovery from ergonomic pain is due, at least in part, to the activation of β2-adrenergic receptors on muscle nociceptors.

Immediate effects of transcutaneous electrical nerve stimulation (TENS) administered during resistance exercise on pain intensity and physical performance of healthy subjects: a randomized clinical trial.

Exercise-induced muscle pain is a self-limiting condition which impacts physical activity habits. Transcutaneous electrical nerve stimulation (TENS) promotes pain reduction and functional improvement in different pain conditions. We propose that applying TENS during exercise might reduce pain and improve physical performance. Thus, we aimed to investigate immediate effects of TENS applied during resistance exercise. Healthy subjects of both sexes, irregularly active or sedentary were assigned into two groups: active (n = 24) or placebo (n = 22) TENS. The study was conducted over five moments: on day 0, subjects were recruited, on day 1 subjects performed the one-repetition maximum test (1RM); 72h later, on day 2, 1RM was retested; 48h later, on day 3, TENS was applied during a functional-resisted exercise protocol for upper limbs (bench press and rowing), with an intensity of 80% of 1RM; and 24h after, on day 4, subjects were reevaluated. Assessment included pain intensity at rest and with movement, pressure pain thresholds, and muscle fatigue. TENS did not reduce pain intensity when compared to placebo (p > 0.05). TENS reduce PPT in the latissmus dorsi: p = 0.02 and anterior tibialis: p = 0.04 in immediate reassessment. Immediate effects of TENS were significant for fatigue perception at rest (p = 0.01) and number of maximum repetitions during exercise sets, starting from the 5th set of rowing exercise (p = 0.002). Our results show that TENS did not reduce pain perception in healthy individuals, but its use induced increased muscle action, contributing to a greater fatigue perception.

A Fast Track to Hypoalgesia - The Anaerobic Exercise Effect on Pain Sensitivity.

Maximal anaerobic exercise, is a short high intensity effort, involves activation of the hypothalamus-pituitary-adrenal axis, and may suggest hypoalgesic effects. In addition, this exercise-induced muscle pain may contribute to hypoalgesia via the pain inhibits pain phenomenon, which is related to the diffuse noxious inhibitory control (DNIC) mechanism. We aimed to investigate whether: 1) a single bout of 30 s maximal anaerobic exercise has an analgesic effect on experimental pain sensitivity; 2) DNIC is the underlying mechanism of anaerobic exercise-induced hypoalgesia (EIH). Fifty healthy subjects participated. The experimental group performed the 'Wingate Anaerobic Test' (WAT) and controls set on the bikes without exercising. Psychophysical tests, performed before and after the intervention, in local and remote areas, included: heat (HPT) and pressure pain thresholds (PPT); suprathreshold heat and cold pain stimulation; the conditioned pain modulation (CPM) paradigm testing the DNIC mechanism. Following WAT, PPT and HPT increased (p<0.001) , pain ratings in response to heat and cold stimuli (p<0.001) and CPM (p=0.029) decreased compared with controls. No correlation was found between muscle pain, blood lactate level and EIH. To conclude WAT induces local and remote analgesic effects. The involvement of central pain modulatory processes with DNIC probably not the underline mechanism of EIH.

No Influence of Transcutaneous Electrical Nerve Stimulation on Exercise-Induced Pain and 5-Km Cycling Time-Trial Performance.

Introduction: Afferent information from exercising muscle contributes to the sensation of exercise-induced muscle pain. Transcutaneous electrical nerve stimulation (TENS) delivers low–voltage electrical currents to the skin, inhibiting nociceptive afferent information. The use of TENS in reducing perceptions of exercise-induced pain has not yet been fully explored. This study aimed to investigate the effect of TENS on exercise-induced muscle pain, pacing strategy, and performance during a 5-km cycling time trial (TT).Methods: On three separate occasions, in a single-blind, randomized, and cross-over design, 13 recreationally active participants underwent a 30-min TENS protocol, before performing a 5-km cycling TT. TENS was applied to the quadriceps prior to exercise under the following conditions; control (CONT), placebo with sham TENS application (PLAC), and an experimental condition with TENS application (TENS). Quadriceps fatigue was assessed with magnetic femoral nerve stimulation assessing changes in potentiated quadriceps twitch force at baseline, pre and post exercise. Subjective scores of exertion, affect and pain were taken every 1-km.Results: During TTs, application of TENS did not influence pain perceptions (P = 0.68, = 0.03). There was no significant change in mean power (P = 0.16, = 0.16) or TT duration (P = 0.17, = 0.14), although effect sizes were large for these two variables. Changes in power output were not significant but showed moderate effect sizes at 500-m ( = 0.10) and 750-m ( = 0.10). Muscle recruitment as inferred by electromyography data was not significant, but showed large effect sizes at 250-m ( = 0.16), 500-m ( = 0.15), and 750-m ( = 0.14). This indicates a possible effect for TENS influencing performance up to 1-km.Discussion: These findings do not support the use of TENS to improve 5-km TT performance.

Transcranial direct current stimulation improves isometric time to exhaustion of the knee extensors

Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area, which may affect endurance exercise performance. However, optimal electrode placement for tDCS remains unclear. We tested the effect of two different tDCS electrode montages for improving exercise performance. Nine subjects underwent a control (CON), placebo (SHAM) and two different tDCS montage sessions in a randomized design. In one tDCS session, the anodal electrode was placed over the left motor cortex and the cathodal on contralateral forehead (HEAD), while for the other montage the anodal electrode was placed over the left motor cortex and cathodal electrode above the shoulder (SHOULDER). tDCS was delivered for 10min at 2.0mA, after which participants performed an isometric time to exhaustion (TTE) test of the right knee extensors. Peripheral and central neuromuscular parameters were assessed at baseline, after tDCS application and after TTE. Heart rate (HR), ratings of perceived exertion (RPE), and leg muscle exercise-induced muscle pain (PAIN) were monitored during the TTE. TTE was longer and RPE lower in the SHOULDER condition (P<0.05). Central and peripheral parameters, and HR and PAIN did not present any differences between conditions after tDCS stimulation (P>0.05). In all conditions maximal voluntary contraction (MVC) significantly decreased after the TTE (P<0.05) while motor-evoked potential area (MEP) increased after TTE (P<0.05). These findings demonstrate that SHOULDER montage is more effective than HEAD montage to improve endurance performance, likely through avoiding the negative effects of the cathode on excitability.