Submaximal Isometric Exercise Research Articles

Unilaterally Induced Quadriceps Fatigue during Sustained Submaximal Isometric Exercise Does Not Alter Contralateral Leg Extensor Performance.

This study investigated the effects of fatiguing unilateral exercise on the ipsilateral, exercised, and contralateral, non-exercised limb's post-exercise performance in males and females. Ten males and ten females performed a fatiguing, unilateral isometric leg extension at 50% maximal voluntary isometric contraction (MVIC) force. Prior to and immediately after the fatiguing tasks, MVICs were performed for the exercised and non-exercised limb, with surface electromyographic (sEMG) and mechanomyography (sMMG) amplitude (AMP) and mean power frequency (MPF) recorded from each limb's vastus lateralis. There were no fatigue-induced, sex-dependent, differences in time to task failure (p = 0.265) or ipsilateral performance fatigability (p = 0.437). However, there was a limb by time interaction (p < 0.001) which indicated decreases in MVIC force of the ipsilateral, exercised (p < 0.001), but not the contralateral, non-exercised limb (p = 0.962). There were no sex-dependent, fatigue-induced differences in neurophysiological outcomes between the limbs (p > 0.05), but there was a fatigue-induced difference in sEMG MPF (p = 0.005). To summarize, there were no differences in fatigability between males and females. Moreover, there was insufficient evidence to support the presence of a general crossover effect following submaximal unilateral isometric exercise. However, independent of sex, the neurophysiological outcomes suggested that competing inputs from the nervous system may influence the performance of both limbs following unilateral fatigue.

Tolerance to submaximal eccentric exercise in women with and without fibromyalgia, moving away from anecdotal beliefs

We have shown people with fibromyalgia experience exacerbated pain in the exercising limb up to three days following submaximal isometric and concentric exercise however, the pain response following eccentric exercise has not been investigated. This study investigated the change in experimental pain up to two days following submaximal eccentric exercise while clinical pain was assessed through the 7-day recovery period in women with and without FM. Eighteen women with fibromyalgia (49.1±11.8yr, BMI: 31.4±7.6) and 18 controls (49.5±10.1yr, BMI: 27.1±4.8) completed session 1 (exercise) and session 2 (recovery assessment) separated by 2 days; session 1 included a 10-minute bout of submaximal (20% of maximal voluntary contraction) eccentric exercise with the right elbow flexors. Pressure pain thresholds (PPTs), mechanical pain summation, and punctate pain summation were assessed before, immediately after exercise, and in session 2. Clinical pain (0-10 NRS) in the exercising arm and whole-body was assessed before, during, immediately after, and up to seven days following the exercise bout. PPTs and mechanical pain summation did not change immediately following exercise or session 2 (Time, p>0.05). Punctate pain summation changed following exercise (Time x Summation, p=0.003) however, post hoc analysis did not reveal a significant difference immediately after exercise (p=0.296) or at session two (p=0.03). The fibromyalgia group reported greater increases in exercising arm pain during (Time x Group, p

Impact of isometric and concentric resistance exercise on pain and fatigue in fibromyalgia.

The aim of this study was to determine the local and systemic effects of isometric and concentric muscle contractions on experimental pain and performance fatigability in people with and without fibromyalgia. Forty-seven fibromyalgia (FM: 51.3 ± 12.3year) and 47 control (CON: 52.5 ± 14.7year) participants performed submaximal isometric and concentric exercise for 10 min with the right elbow flexors. Assessments before and after exercise included pressure pain thresholds (PPT) of the biceps and quadriceps, central pain summation, self-reported exercising arm and whole-body pain, and maximal voluntary isometric contraction (MVIC) of the right elbow flexors and left handgrip. People with FM experienced greater reductions in local fatigue (right elbow flexor MVIC: CON: - 4.0 ± 6.7%, FM: - 9.8 ± 13.8%; p = 0.013) and similar reductions in systemic fatigue (left handgrip MVIC: - 6.5 ± 10.2%; p < 0.001) as CON participants, which were not different by contraction type nor related to baseline clinical pain, perceived fatigue, or reported pain with exercise. Following exercise both groups reported an increase in PPTs at the biceps (pre: 205.5 ± 100.3kPa, post: 219.0 ± 109.3kPa, p = 0.004) only and a decrease in central pain summation (pre: 6.8 ± 2.9, post: 6.5 ± 2.9; p = 0.013). FM reported greater exercising arm pain following exercise (CON: 0.7 ± 1.3, FM: 2.9 ± 2.3; p < 0.001), and both groups reported greater arm pain following concentric (isometric: 1.4 ± 2.0, concentric: 2.2 ± 2.9; p = 0.001) than isometric exercise. Neither group reported an increase in whole-body pain following exercise. People with FM experienced greater performance fatigability in the exercising muscle compared to CON that was not related to central mechanisms of fatigue or pain. These results suggest changes in performance fatigability in FM may be due to differences occurring at the muscular level. TRIAL REGISTRATION #: NCT #: NCT03778385, December 19, 2018, retrospectively registered. IRB#: HR-3035.

Ischemic Preconditioning Did Not Affect Central and Peripheral Factors of Performance Fatigability After Submaximal Isometric Exercise.

The present study was designed to provide further insight into the mechanistic basis for the improved exercise tolerance following ischemic preconditioning (IPC) by investigating key-determinants of performance and perceived fatigability. Using a randomized, counterbalanced, single-blind, sham-controlled, crossover design, 16 males performed an isometric time-to-exhaustion test with the knee extensors at 20% maximal voluntary torque (MVT) after an IPC and a sham treatment (SHAM). Those who improved their time-to-exhaustion following IPC performed a time-matched IPC trial corresponding to the exercise duration of SHAM (IPCtm). Neuromuscular function was assessed before and after exercise termination during each condition (IPC, IPCtm, and SHAM) to analyze the impact of IPC on performance fatigability and its central and peripheral determinants. Muscle oxygenation (SmO2), muscle activity, and perceptual responses (effort and muscle pain) were recorded during exercise. Performance fatigability as well as its central and peripheral determinants were quantified as percentage pre-post changes in MVT (ΔMVT) as well as voluntary activation (ΔVA) and quadriceps twitch torque evoked by paired electrical stimuli at 100 and 10 Hz (ΔPS100 and ΔPS10⋅PS100–1 ratio), respectively. Time-to-exhaustion, performance fatigability, its determinants, muscle activity, SmO2, and perceptual responses during exercise were not different between IPC and SHAM. However, six participants improved their performance by >10% following IPC (299 ± 71 s) compared to SHAM (253 ± 66 s, d = 3.23). The time-matched comparisons (IPCtm vs. SHAM) indicated that performance fatigability, its determinants, and SmO2 were not affected, while effort perception seemed to be lower (ηp2 = 0.495) in those who improved their time-to-exhaustion. The longer time-to-exhaustion following IPC seemed to be associated with a lower effort perception (ηp2 = 0.380) and larger impairments in neuromuscular function, i.e., larger ΔMVT, ΔVA, and ΔPS10⋅PS100–1 ratio (d = 0.71, 1.0, 0.92, respectively). IPC did neither affect exercise tolerance, performance fatigability, as well as its central and peripheral determinants, nor muscle activity, SmO2, and perceptual responses during submaximal isometric exercise. However, IPC seemed to have an ergogenic effect in a few subjects, which might have resulted from a lower effort perception during exercise. These findings support the assumption that there are ‘responders’ and ‘non-responders’ to IPC.

Isometric Exercise with Large Muscle Mass Improves Redox Balance and Blood Pressure in Hypertensive Adults.

The aim of this study was to investigate the hemodynamic, oxidative stress (OS), and nitric oxide (NO) responses to a submaximal isometric exercise session (IES) involving large muscle mass. Fourteen hypertensive (HTG: age = 35.9 ± 8.1 yr, height = 1.73 ± 0.10 m, total body mass = 78.0 ± 15.8 kg) and 10 normotensive (NTG: age = 41.1 ± 9.4 yr, height = 1.71 ± 0.12 m, total body mass = 82.3 ± 22.4 kg) participants performed two experimental sessions in the leg press and bench press: (i) control session and (ii) 8 sets × 1 min contraction at 30% maximal voluntary isometric contraction with 2-min rest interval. Blood pressure (BP) was measured at rest and during 60 min postexercise. Blood samples were collected at rest, immediately after the session, and 60 min postexercise. NO was obtained through the Griess reaction method. OS parameters were analyzed using commercial kits. A repeated-measures ANOVA with Bonferroni post hoc test was used to analyze all dependent variables. A significant decrease in systolic BP was observed only for HTG at 45 and 60 min postexercise (baseline vs 45 min: P = 0.03, Δ% = 4.44%; vs 60 min: P = 0.018, Δ% = 5.58%). NO increased immediately postexercise only for HTG (P = 0.008, Δ% = 16.44%). Regarding OS parameters, thiobarbituric acid reactive substances presented a significant reduction 60 min after the IES for NTG and HTG; catalase increased in both groups. The data showed that only 8 min of IES with a large muscle mass elicits an elevated pro-oxidant activity leading to a greater NO bioavailability, increases antioxidant reaction, and consequently reduces BP in hypertensive patients.

Echocardiography during submaximal isometric exercise in children with repaired coarctation of the aorta compared with controls

ObjectivePatients with repaired coarctation (RCoA) remain at higher risk of cardiac dysfunction, initially often only detected during exercise. In this study, haemodynamics of isometric handgrip (HG) and bicycle ergometry (BE)...

(305) The Contribution of Experimental Pain to the Sex Differences in Exercise-Induced Hypoalgesia

The aim of this study was to investigate the effect of baseline (pre-exercise) temporal summation (TS) on the change of TS following submaximal isometric exercise in young healthy men (M) and women (W). Fifty-seven participants (20.75 ± 1.81 years; 29 women) completed two randomized sessions (exercise or quiet rest session). Isometric exercise consisted of sustained contraction of the knee extensors at 30% of maximum voluntary contraction performed until task failure. TS was assessed by applying a mechanical noxious stimulus equivalent to either 1kg (Low group) or 1.5 kg (High group) on the index finger. The mechanical noxious stimulus was applied for one minute beyond pain threshold, and subjects were instructed to rate their pain every 15 seconds on a numerical pain rating scale (0-10). TS was evaluated before and after exercise and quiet rest. The magnitude of TS was calculated as: [last pain rating – first pain rating]. The change of TS was compared between the two groups within each sex (M-High, M-Low, W-High, and W-Low). Sex differences in exercise-induced hypoalgesia (EIH) occurred among the high TS stimulus intensity group (session X trial X sex X group; p= 0.01); only W-High group experienced EIH while M-High experienced no change (session X trial X sex; p=0.039). Among women, the W-High had greater EIH than W-Low (session X trial X group; p= 0.049). In addition, pre-exercise TS was positively correlated with the magnitude of EIH (r= 0.34, p= 0.01). These results suggest that baseline experimental pain may contribute to the magnitude of EIH and to the sex differences in EIH.

Physical Activity Levels Predict Exercise-induced Hypoalgesia in Older Adults

This study examined potential psychological and physical activity predictors of the magnitude of EIH after submaximal isometric exercise in healthy older adult men and women. Fifty-two healthy older adults completed a test of EIH, the Pain Catastrophizing Scale, the Tampa Scale of Kinesiophobia, and wore an accelerometer on the hip for 1 wk to assess physical activity levels. For the test of EIH, participants complete a 3-min isometric handgrip at 25% of maximum voluntary contraction. Pressure pain thresholds (PPT) and a 30-s continuous heat pain test were completed before and immediately after the exercise. Mixed-model ANOVA revealed that older adults demonstrated significantly decreased PPT after isometric exercise (P = 0.030), and no changes on the heat pain trials from pretest to posttest (P > 0.05). A multiple regression revealed that accumulated moderate to vigorous physical activity (MVPA) per week significantly predicted the change in PPT after exercise (β = 0.35, P = 0.012). Participants who averaged greater MVPA experienced a greater increase in PPT after exercise. No relationships were found with EIH and the psychological variables. Older adults did not exhibit EIH after submaximal isometric exercise. However, those who did more MVPA per week experienced a greater magnitude of pain inhibition after acute exercise.

A brief submaximal isometric exercise test 'unmasks' systolic and diastolic masked hypertension.

An exaggerated blood pressure (BP) response during dynamic exercise testing has been proposed as an additional screening tool to identify systolic masked hypertension (masked-HYP). However, masked-HYP in young people is often characterized by an elevated DBP. Static/isometric exercise elicits augmented sympathetic stimulation causing greater increases in both SBP and DBP than dynamic exercise. To examine whether individuals with masked-HYP exhibit exaggerated BP responses during a submaximal handgrip vs. normotensive individuals and individuals with sustained hypertension (true-HYP), and the possible associations of exercise BP with total peripheral resistance (TPR), central/aortic BP, and 24-h-ambulatory BP (24-h BP). Eighty-six participants [untreated, newly diagnosed, masked-HYP (n = 27), true-HYP (n = 31), and normotensive individuals (n = 28); 46.3 ± 10.7 years], following evaluation of office BP, central/aortic BP, pulse wave velocity, carotid intima-media thickness, echocardiocardiography, and 24-h BP, underwent a 3-min handgrip (30% maximal voluntary contraction) with beat-by-beat BP and hemodynamics assessment (Finapres Medical Systems). Despite similar baseline-BP in masked-HYP and normotensive individuals, during exercise masked-HYP exhibited a markedly greater (P < 0.01) SBP and DBP vs. normotensive individuals, and similar BP to true-HYP. TPR significantly increased (P < 0.001) during exercise, in masked-HYP and true-HYP. The exaggerated BP responses in masked-HYP were evident from the 1st minute of exercise and correlated (P < 0.05) with central/aortic-BP, aortic stiffness, 24-h BP, day-BP, night-time-BP, and interventricular septum thickness. During handgrip, masked-HYP exhibited exaggerated BP and TPR responses, similar to those of true-HYP. These responses were evident from the 1st minute of exercise and correlated with 24-h BP, suggesting that systolic and diastolic masked-HYP can be 'unmasked' during a brief, submaximal, handgrip test.

Is perceived force an accurate method of regulating exercise load for the neck?

ABSTRACTObjective: Patient perceived level of force is commonly used to regulate exercise load. This study determined the accuracy of perceived force as a method of regulating exercise load for the cervical flexors and extensors. Methods: Thirty healthy individuals performed submaximal isometric cervical flexion and extension exercise at perceived intensities (25%, 50%, and 75%) of their maximal voluntary contraction (MVC) with no feedback in a neck dynamometer. Measurements of “actual” versus “perceived” force levels were compared before and after the performance of an MVC. Data were analyzed descriptively and the relationship between performance error, test, and participant factors examined. Results: With the exception of the 25% MVC extension trials post-MVC, an underestimation of force was observed over all conditions that worsened as the target force increased (50% and 75%) with only some improvement following the experience of an MVC (p < 0.001). Linear mixed modeling indicated participants familiar with exercise may have better accuracy (p = 0.07). Conclusion: Regulating isometric resistance exercise load of the neck based on a perceived proportion of MVC force may only be accurate at low intensities (25% MVC) but not for moderate to high (50–75%) intensities.

Brief submaximal isometric exercise improves cold pressor pain tolerance

Exercise-induced hypoalgesia (EIH), or the inhibition of pain following physical exercise, has been demonstrated in adults, but its mechanisms have remained unclear due to variations in methodology. This study aimed to address methodological imitations of past studies and contribute to the literature demonstrating the generalizability of EIH to brief submaximal isometric exercise and cold pressor pain. Young adults (n=134) completed a baseline cold pressor trial, maximal voluntary contraction (hand grip strength) assessment, 10-min rest, and either a 2-min submaximal isometric handgrip exercise or a sham exercise in which no force was exerted, followed by a cold pressor posttest. Results indicated that cold pressor pain tolerance significantly increased during the exercise condition, but not during the sham exercise condition. Exercise did not affect pain intensity and marginally affected pain unpleasantness ratings. These findings suggest that submaximal isometric exercise can improve cold pressor pain tolerance but may have an inconsistent analgesic effect on ratings of cold pressor pain.

Integration of active pauses and pattern of muscular activity during computer work

Submaximal isometric muscle contractions have been reported to increase variability of muscle activation during computer work; however, other types of active contractions may be more beneficial. Our objective was to determine which type of active pause vs. rest is more efficient in changing muscle activity pattern during a computer task. Asymptomatic regular computer users performed a standardised 20-min computer task four times, integrating a different type of pause: sub-maximal isometric contraction, dynamic contraction, postural exercise and rest. Surface electromyographic (SEMG) activity was recorded bilaterally from five neck/shoulder muscles. Root-mean-square decreased with isometric pauses in the cervical paraspinals, upper trapezius and middle trapezius, whereas it increased with rest. Variability in the pattern of muscular activity was not affected by any type of pause. Overall, no detrimental effects on the level of SEMG during active pauses were found suggesting that they could be implemented without a cost on activation level or variability.Practitioner Summary: We aimed to determine which type of active pause vs. rest is best in changing muscle activity pattern during a computer task. Asymptomatic computer users performed a standardised computer task integrating different types of pauses. Muscle activation decreased with isometric pauses in neck/shoulder muscles, suggesting their implementation during computer work.

Exercise increases pressure pain tolerance but not pressure and heat pain thresholds in healthy young men.

Exercise causes an acute decrease in the pain sensitivity known as exercise-induced hypoalgesia (EIH), but the specificity to certain pain modalities remains unknown. This study aimed to compare the effect of isometric exercise on the heat and pressure pain sensitivity. On three different days, 20 healthy young men performed two submaximal isometric knee extensions (30% maximal voluntary contraction in 3min) and a control condition (quiet rest). Before and immediately after exercise and rest, the sensitivity to heat pain and pressure pain was assessed in randomized and counterbalanced order. Cuff pressure pain threshold (cPPT) and pain tolerance (cPTT) were assessed on the ipsilateral lower leg by computer-controlled cuff algometry. Heat pain threshold (HPT) was recorded on the ipsilateral foot by a computer-controlled thermal stimulator. Cuff pressure pain tolerance was significantly increased after exercise compared with baseline and rest (p<0.05). Compared with rest, cPPT and HPT were not significantly increased by exercise. No significant correlation between exercise-induced changes in HPT and cPPT was found. Test-retest reliability before and after the rest condition was better for cPPT and CPTT (intraclass correlation>0.77) compared with HPT (intraclass correlation=0.54). The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the pain threshold. These data contribute to the understanding of how isometric exercise influences pain perception, which is necessary to optimize the clinical utility of exercise in management of chronic pain. The effect of isometric exercise on pain tolerance may be relevant for patients in chronic musculoskeletal pain as a pain-coping strategy. WHAT DOES THIS STUDY ADD?: The results indicate that hypoalgesia after submaximal isometric exercise is primarily affecting tolerance of pressure pain compared with the heat and pressure pain threshold. These data contribute to the understanding of how isometric exercise influences pain perception, which is necessary to optimize the clinical utility of exercise in management of chronic pain.

Reduced Modulation of Pain in Older Adults After Isometric and Aerobic Exercise.

Laboratory-based studies show that acute aerobic and isometric exercise reduces sensitivity to painful stimuli in young healthy individuals, indicative of a hypoalgesic response. However, little is known regarding the effect of aging on exercise-induced hypoalgesia (EIH). The purpose of this study was to examine age differences in EIH after submaximal isometric exercise and moderate and vigorous aerobic exercise. Healthy older and younger adults completed 1 training session and 4 testing sessions consisting of a submaximal isometric handgrip exercise, vigorous or moderate intensity stationary cycling, or quiet rest (control). The following measures were taken before and after exercise/quiet rest: 1) pressure pain thresholds, 2) suprathreshold pressure pain ratings, 3) pain ratings during 30seconds of prolonged noxious heat stimulation, and 4) temporal summation of heat pain. The results revealed age differences in EIH after isometric and aerobic exercise, with younger adults experiencing greater EIH compared with older adults. The age differences in EIH varied across pain induction techniques and exercise type. These results provide evidence for abnormal pain modulation after acute exercise in older adults. This article enhances our understanding of the influence of a single bout of exercise on pain sensitivity and perception in healthy older compared with younger adults. This knowledge could help clinicians optimize exercise as a method of pain management.

Effects of caffeinated chewing gum on muscle pain during submaximal isometric exercise in individuals with fibromyalgia

Physical activity is important to manage symptom of fibromyalgia (FM); however, individuals with FM typically experience augmented muscle pain during exercise. This study examined the effects of caffeinated chewing gum on exercise-induced muscle pain in individuals with FM. This study was conducted with a double-blind, placebo-controlled, cross-over design. Twenty-three patients with FM completed a caffeine condition where they consumed a caffeinated chewing gum that contains 100mg of caffeine, and a placebo condition where they consumed a non-caffeinated chewing gum. They completed isometric handgrip exercise at 25% of their maximal strength for 3min, and muscle pain rating (MPR) was recorded every 30s during exercise. Clinical pain severity was assessed in each condition using a pain questionnaire. The order of the two conditions was randomly determined. MPR increased during exercise, but caffeinated chewing gum did not attenuate the increase in MPR compared to placebo gum. Clinical pain severity was generally associated with the average MPR and the caffeine effects on MPR, calculated as difference in the average MPR between the two conditions. The results suggest that more symptomatic individuals with FM may experience greater exercise-induced muscle pain, but benefit more from caffeinated chewing gum to reduce exercise-induced muscle pain.

Mechanisms of Exercise-Induced Hypoalgesia

The purpose of this study was to examine opioid and endocannabinoid mechanisms of exercise-induced hypoalgesia (EIH). Fifty-eight men and women (mean age = 21 years) completed 3 sessions. During the first session, participants were familiarized with the temporal summation of heat pain and pressure pain protocols. In the exercise sessions, following double-blind administration of either an opioid antagonist (50 mg naltrexone) or placebo, participants rated the intensity of heat pulses and indicated their pressure pain thresholds and pressure pain ratings before and after 3 minutes of submaximal isometric exercise. Blood was drawn before and after exercise. Results indicated that circulating concentrations of 2 endocannabinoids, N-arachidonylethanolamine and 2-arachidonoylglycerol, as well as related lipids oleoylethanolamide, palmitoylethanolamide, N-docosahexaenoylethanolamine, and 2-oleoylglycerol, increased significantly (P < .05) following exercise. Pressure pain thresholds increased significantly (P < .05), whereas pressure pain ratings decreased significantly (P < .05) following exercise. Also, temporal summation ratings were significantly lower (P < .05) following exercise. These changes in pain responses did not differ between the placebo and naltrexone conditions (P > .05). A significant association was found between EIH and docosahexaenoylethanolamine. These results suggest involvement of a nonopioid mechanism in EIH following isometric exercise. PerspectiveCurrently, the mechanisms responsible for EIH are unknown. This study provides support for a potential endocannabinoid mechanism of EIH following isometric exercise.

Isometric Exercise as a Test of Pain Modulation: Effects of Experimental Pain Test, Psychological Variables, and Sex

Little is known regarding whether exercise-induced hypoalgesia (EIH) produced by isometric exercise is influenced by psychological factors or systematically varies across multiple experimental psychophysical pain tests. Thus, this study sought to determine the influence of experimental pain test, psychological factors, and sex on the hypoalgesic response of submaximal isometric exercise. Healthy young males (N = 12) and females (N = 15) completed one training and two testing sessions consisting of quiet rest (control condition) or a 3-minute isometric handgrip performed at 25% of maximum voluntary contraction. Pain testing was conducted on both forearms prior to and following exercise and quiet rest. The pain tests included: pressure pain thresholds (PPT), suprathreshold pressure pain test, static prolonged heat test, and temporal summation of heat pain. Participants completed the Pain Catastrophizing Scale during the training session and the State-Trait Anxiety Inventory-State version prior to each session. The data were analyzed with mixed model analyses of variance, partial Pearson correlations, and hierarchical regression analyses. Isometric exercise increased PPTs for men and women, reduced pain perception during static prolonged heat stimuli for women, and reduced temporal summation of pain for men and women. Greater pain catastrophizing was associated with smaller reductions in temporal summation following isometric exercise. These findings demonstrate that the hypoalgesic response to submaximal isometric exercise is partially a function of sex and experimental pain test. Furthermore, the relationship between EIH and pain catastrophizing was psychophysical pain test specific, with greater pain catastrophizing predicting diminished EIH only during the temporal summation of pain trials.

The influence of submaximal isometric exercise on temporal summation of heat pain

Numerous studies have indicated an attenuation of pain following exercise in healthy young adults, and this phenomenon has been referred to as exercise-induced hypoalgesia. Little is known, however, about the effect of short duration isometric exercise (i.e., static muscular contraction) on temporal summation of pain. Thus, the purpose of this study was to examine the influence of submaximal isometric exercise on the temporal summation of heat pain in men and women. Fifty-two men and women with a mean age of 21 yrs (sd = 3) participated in this study. Ten heat pulses were applied to the thenar eminence of the dominant hand using a standardized temporal summation protocol. Participants rated the intensity of the heat pulses using a 0-100 rating scale at baseline, before, and following isometric exercise which consisted of squeezing a hand dynamometer at 25% of maximum for 3 minutes. The data were analyzed with a 2 (sex) X 3 (trials: baseline, pre, and post) X 3 (pulses: 1, 5, and 10) repeated measures ANOVA. The results indicated a significant reduction (p < 0.05) in pain ratings following isometric exercise. The magnitude of reduction in temporal summation of heat pain was moderate (effect sizes for the men = 0.37-0.40 and for the women = 0.57-0.64). It is concluded that short duration, submaximal isometric exercise was associated with a reduction in temporal summation of heat pain in men and women. Supported by NIH grant R21AR057159. Numerous studies have indicated an attenuation of pain following exercise in healthy young adults, and this phenomenon has been referred to as exercise-induced hypoalgesia. Little is known, however, about the effect of short duration isometric exercise (i.e., static muscular contraction) on temporal summation of pain. Thus, the purpose of this study was to examine the influence of submaximal isometric exercise on the temporal summation of heat pain in men and women. Fifty-two men and women with a mean age of 21 yrs (sd = 3) participated in this study. Ten heat pulses were applied to the thenar eminence of the dominant hand using a standardized temporal summation protocol. Participants rated the intensity of the heat pulses using a 0-100 rating scale at baseline, before, and following isometric exercise which consisted of squeezing a hand dynamometer at 25% of maximum for 3 minutes. The data were analyzed with a 2 (sex) X 3 (trials: baseline, pre, and post) X 3 (pulses: 1, 5, and 10) repeated measures ANOVA. The results indicated a significant reduction (p < 0.05) in pain ratings following isometric exercise. The magnitude of reduction in temporal summation of heat pain was moderate (effect sizes for the men = 0.37-0.40 and for the women = 0.57-0.64). It is concluded that short duration, submaximal isometric exercise was associated with a reduction in temporal summation of heat pain in men and women. Supported by NIH grant R21AR057159.

Typing keystroke duration changed after submaximal isometric finger exercises

A repeated-measures laboratory experiment tested whether keystroke duration during touch-typing changes after a finger performs submaximal isometric flexion exercises. Fourteen right-handed touch-typists used right ring finger to perform three 15-min exercise conditions, two isometric exercises and a no-force condition, each on a separate day. Before and after each exercise condition, typing keystroke duration and isometric force elicited by electrical stimulation were measured for right ring finger. Keystroke duration of right ring finger decreased by 5% (6 ms, P < 0.05) immediately after the exercises but not after the no-force condition. Peak isometric finger force elicited by electrical stimulation decreased by 17-26% (P < 0.05) for the flexor digitorum superficialis and decreased by 4-8% for the extensor digitorum communis after the isometric exercises. After the finger was exposed to isometric exercises, changes in typing keystroke duration coincided with changes in the physiological state of the finger flexor and extensor muscles.

Contralateral Attenuation of Pain After Short-Duration Submaximal Isometric Exercise

Only a small amount of research has been conducted examining whether exercise-induced hypoalgesia (EIH) occurs after isometric exercise. Thus, the purpose of this investigation was to examine whether EIH occurred in women after short-duration submaximal isometric exercise and whether the responses were restricted to the exercised hand (ipsilateral) or also occurred in the nonexercised (contralateral) hand. Fourteen healthy women (mean age = 19.5 years) completed 2 sets of submaximal (40% to 50% of max) isometric exercise consisting of squeezing a dynamometer for 2 minutes with the dominant hand. A pressure stimulus was applied to the forefinger on the dominant and nondominant hands for 2 minutes before and after isometric exercise. Participants pressed a button when the stimulus became painful, indicating pain threshold (PT), and also rated the intensity of the stimulus every 15 seconds, using a pain rating scale (PR). Results indicated that there were significant trials effects (P < .05) for PT and PR, but the main effect for hands was not significant (P > .05). PTs were found to be elevated, whereas PRs were reduced for both hands after isometric exercise. It is concluded that submaximal isometric exercise performed for 2 minutes resulted in ipsilateral and contralateral hypoalgesic responses. The findings from the present study demonstrated that short-duration nonexhaustive isometric exercise was associated with hypoalgesic responses in the exercised and nonexercised hands. It appears that short-duration submaximal isometric exercise resulted in generalized (ie, ipsilateral and contralateral) pain-inhibitory responses in healthy young women.