Effect of electrical muscle stimulation on cerebrovascular function and cognitive performance.

It is known that electrical muscle stimulation (EMS) can enhance physical function, but its impact on cognition and cerebral hemodynamics is not well understood. Thus, the purpose of this study was to investigate the effects of one EMS session on cerebrovascular function and cognitive performance. The 17 recruited young healthy participants undertook a 25-min session of EMS and a resting control session (Ctrl group) in a random order. Cerebral blood flow velocity (CBFv) in the middle and posterior cerebral arteries (right MCAv and left PCAv, respectively), cerebral oxygenation, cardiac output, and heart rate were measured throughout the sessions, whereas cognitive function was assessed before and after each experimental condition. MCAv, cardiac output, heart rate, and cerebral oxygenation were increased throughout the EMS session, whereas PCAv remained unchanged. In addition, EMS led to improved scores at the Rey auditory verbal learning test-part B and congruent Stroop task versus Ctrl. The present study demonstrates that a single session of EMS may improve cognitive performance and concomitantly increase CBFv and cerebral oxygenation. Therefore, EMS appears to be a valuable surrogate for voluntary exercise and could therefore be advantageously used in populations with severe physical limitations who would not be able to perform physical exercise otherwise.NEW & NOTEWORTHY This study is the first to demonstrate that one session of EMS applied to the quadriceps increases cerebral blood flow velocity and cerebral oxygenation, which are pivotal factors for brain health. Thus, EMS has the potential to be used as an interesting option in rehabilitation to increase cerebral perfusion and defend if not improve cognitive function sustainably for people with severe physical limitations who would not be able to perform physical exercise voluntarily.

Effects of electrical stimulation pattern on quadriceps isometric force and fatigue in individuals with spinal cord injury.

INTRODUCTION: Variable frequency trains (VFT) or train combinations have been suggested as useful strategies to offset the rapid fatigue induced by constant frequency trains (CFT) during electrical stimulation. However, most studies have been of short duration with limited functional application in those with spinal cord injury (SCI). We therefore tested force and fatigue in response to VFT, CFT, and combined patterns in strength training-like conditions (6-s contractions). METHODS: Ten SCI individuals underwent either CFT or VFT patterns until target torque was no longer produced and then switched immediately to the other pattern. RESULTS: Target torque was reached more times when VFT was used first (VFT: 6.7 ± 0.8 vs. CFT: 3.5 ± 0.2 contractions, P < 0.05) and when it was followed by the CFT pattern (VFT-CFT: 10.3 ± 1.2 vs. CFT-VFT: 6.9 ± 1.2 contractions, P < 0.05). CONCLUSIONS: These findings suggest that for the same initial forces the VFT pattern is less fatiguing than CFT and that when combining train types, VFT should be used first.

Effects of electrical stimulation pattern on quadriceps force production and fatigue.

INTRODUCTION: Mixed stimulation programs (MIX) that switch from constant frequency trains (CFT) to variable frequency trains have been proposed to offset the rapid fatigue induced by CFT during electrical stimulation. However, this has never been confirmed with long stimulation patterns, such as those used to evoke functional contractions. The purpose of this study was to test the hypothesis that MIX programs were less fatiguing than CFTs in strength training-like conditions (6-s contractions, 30-min). METHODS: Thirteen healthy subjects underwent 2 sessions corresponding to MIX and CFT programs. Measurements included maximal voluntary isometric torque and torque evoked by each contraction. RESULTS: There were greater decreases of voluntary and evoked torque (P < 0.05) after CFT than MIX, and mean torque was 13 ± 1% higher during the MIX session (P < 0.05). CONCLUSIONS: These findings confirm that combining train types might be a useful strategy to offset rapid fatigue during electrical stimulation sessions with long-duration contractions.

Hybrid functional electrical stimulation exercise training alters the relationship between spinal cord injury level and aerobic capacity.

OBJECTIVE: To test the hypothesis that hybrid functional electrical stimulation (FES) row training would improve aerobic capacity but that it would remain strongly linked to level of spinal cord lesion because of limited maximal ventilation. DESIGN: Longitudinal before-after trial of 6 months of FES row training. SETTING: Exercise for persons with disabilities program in a hospitaL. PARTICIPANTS: Volunteers (N=14; age range, 21-63y) with complete spinal cord injury (SCI) (T3-11) who are >2 years postinjury. INTERVENTION: Six months of FES row training preceded by a variable period of FES strength training. MAIN OUTCOME MEASURES: Peak aerobic capacity and peak exercise ventilation before and after 6 months of FES row training. RESULTS: FES row training significantly increased peak aerobic capacity and peak minute ventilation (both P<.05). Prior to FES row training, there was a close relation between level of SCI and peak aerobic capacity (adjusted R(2)=.40, P=.009) that was markedly reduced after FES row training (adjusted R(2)=.15, P=.10). In contrast, the relation between level of injury and peak minute ventilation was comparable before and after FES row training (adjusted R(2)=.38 vs .32, both P<.05). CONCLUSIONS: The increased aerobic capacity reflects more than increased ventilation; FES row training effectively circumvents the effect of SCI on peak aerobic capacity by engaging more muscle mass for training, independent of the level of injury.

Could Low-Frequency Electromyostimulation Training be an Effective Alternative to Endurance Training? An Overview in One Adult.

This preliminary study aimed to investigate the effects of a six-week low-frequency electromyostimulation training (10Hz) on the cardiovascular, respiratory and muscular systems. To that purpose, aerobic capacity, knee extensor muscles strength and architecture, muscle sympathetic nervous activity, blood pressure and heart rate have been evaluated in one healthy male subject (33 year-old, 1.73 m, 73 kg). Results showed improvement of aerobic capacity (+4.5% and +11.5% for maximal oxygen uptake and ventilatory threshold) and muscle strength (+11% and +16% for voluntary and evoked force). Moreover, for the first time, this study demonstrated low-frequency training effects on muscle architecture (+3%, +12% and -11% for muscle thickness, pennation angle and fascicle length) and cardiovascular parameters (-22%, -18% and -21% for resting muscle sympathetic nervous activity, heart rate and mean blood pressure). Interestingly, these results suggest that this method may have beneficial effects on all systems of the body. The investigation of training effects on muscle architecture and cardiovascular parameters should therefore be pursued since highly deconditioned subjects are likely to fully benefit from these adaptations. Key pointsThese results confirmed that 5 weeks of low-frequency electrical stimulation have beneficial effects on aerobic capacity and muscle strength.This study demonstrated that low-frequency electrical stimulation applied for as short as 5 weeks have a great impact on muscle architecture and cardiovascular parameters and control.This type of training might therefore be interesting for rehabilitation of patients who are unable to perform endurance exercises.

FES-rowing: a well-tolerated and highly beneficial exercise for a patient with Brown-Sequard syndrome.

CONTEXT: Brown-Séquard Syndrome (BSS) is a rare neurological condition associated with Spinal Cord Injury (SCI). Hemisection of the spinal cord causes paralysis of the homolateral side, and thermoalgesic dysfunction on the opposite side. Cardiopulmonary and metabolic alterations have been reported. For all these patients, regular physical activity is highly recommended and functional electrical stimulation (FES) may be a good option, especially for those with paraplegia. However, to our knowledge, the effects of FES have primarily been studied in those with complete SCI and data regarding application and effects in patients with incomplete lesions (with sensory feedback) is lacking. The present case report therefore evaluated the feasibility and effectiveness of a 3-month FES-rowing program in a patient with BSS. METHODS: Knee extensor muscle strength and thickness, walking and rowing capacities as well as quality of life were evaluated before and after 3 months of FES-rowing (two sessions per week) in a 54 year old patient with BSS. RESULTS: The individual had excellent tolerance and adherence to the training protocol. All measured parameters were greatly improved after 3 months: on average, + 30% rowing capacity, + 26% walking capacity, + 24.5% isometric strength, + 21.9% quadriceps muscle thickness, + 34.5% quality of life. CONCLUSION: FES-rowing appears to be well tolerated and highly beneficial for a patient with incomplete SCI and could therefore be considered as an appealing exercise option for these patients.

Does electrical stimulation enhance post-exercise performance recovery?

Elite sport requires high-volume and high-intensity training that inevitably induces neuromuscular fatigue detrimental for physical performance. Improving recovery processes is, therefore, fundamental and to this, a wide variety of recovery modalities could be proposed. Among them, neuromuscular electrical stimulation is largely adopted particularly by endurance-type and team sport athletes. This type of solicitation, when used with low stimulation frequencies, induces contractions of short duration and low intensity comparable to active recovery. This might be of interest to favour muscle blood flow and therefore metabolites washout to accelerate recovery kinetics during and after fatiguing exercises, training sessions or competition. However, although electrical stimulation is often used for recovery, limited evidence exists regarding its effects for an improvement of most physiological variables or reduced subjective rating of muscle soreness. Therefore, the main aim of this brief review is to present recent results from the literature to clarify the effectiveness of electrical stimulation as a recovery modality.

Effects of combined electromyostimulation and gymnastics training in prepubertal girls.

This study investigated the effects of a 6-week combined electromyostimulation (EMS) and gymnastic training program on muscle strength and vertical jump performance of prepubertal gymnasts. Sixteen young women gymnasts (age 12.4 ± 1.2 yrs) participated in this study, with 8 in the EMS group and the remaining 8 as controls. EMS was conducted on knee extensor muscles for 20 minutes 3 times a week during the first 3 weeks and once a week during the last 3 weeks. Gymnasts from both groups underwent similar gymnastics training 5-6 times a week. Isokinetic torque of the knee extensors was determined at different eccentric and concentric angular velocities ranging from -60 to +240° per second. Jumping ability was evaluated using squat jump (SJ), counter movement jump (CMJ), reactivity test, and 3 gymnastic-specific jumps. After the first 3 weeks of EMS, maximal voluntary torque was increased (+40.0 ± 10.0%, +35.3 ± 11.8%, and +50.6 ± 7.7% for -60, +60, and +240°s⁻¹, respectively; p < 0.05), as well as SJ, reactivity test and specific jump performances (+20.9 ± 8.3%, +20.4 ± 26.2% and +14.9 ± 17.2% respectively; p < 0.05). Six weeks of EMS were necessary to improve the CMJ (+10.1 ± 10.0%, p < 0.05). Improvements in jump ability were still maintained 1 month after the end of the EMS training program. To conclude, these results first demonstrate that in prepubertal gymnasts, a 6-week EMS program, combined with the daily gymnastic training, induced significant increases both in knee extensor muscle strength and nonspecific and some specific jump performances.

Effects of between-set interventions on neuromuscular function during isokinetic maximal concentric contractions of the knee extensors.

The presents study investigated the effects of between-set interventions on neuromuscular function of the knee extensors during six sets of 10 isokinetic (120°·s(-1)) maximal concentric contractions separated by three minutes. Twelve healthy men (age: 23.9 ± 2.4 yrs) were tested for four different between-set recovery conditions applied during two minutes: passive recovery, active recovery (cycling), electromyostimulation and stretching, in a randomized, crossover design. Before, during and at the end of the isokinetic session, torque and thigh muscles electromyographic activity were measured during maximal voluntary contractions and electrically-evoked doublets. Activation level was calculated using the twitch interpolation technique. While quadriceps electromyographic activity and activation level were significantly decreased at the end of the isokinetic session (-5.5 ± 14.2 % and -2.7 ± 4.8 %; p < 0.05), significant decreases in maximal voluntary contractions and doublets were observed after the third set (respectively -0.8 ± 12.1% and -5.9 ± 9.9%; p < 0.05). Whatever the recovery modality applied, torque was back to initial values after each recovery period. The present results showed that fatigue appeared progressively during the isokinetic session with peripheral alterations occurring first followed by central ones. Recovery interventions between sets did not modify fatigue time course as compared with passive recovery. It appears that the interval between sets (3 min) was long enough to provide recovery regardless of the interventions. Key pointsAllowing three minutes of recovery between sets of 10 maximal concentric contractions would help the subjects to recover from the peripheral fatigue induced by each set and therefore to start each new set with a high intensity.During this type of session, with three minutes between sets, passive recovery is sufficient; there is no need to apply complicated recovery interventions.

Effects of Light Pedaling Added to Contrast Water Immersion for Recovery after Exhaustive Exercise.

For years, athletes and coaches have been looking for new strategies to optimize post-exercise recovery; it has recently been suggested that combining several methods might be a great option. This study therefore aimed to investigate the efficacy of contrast water therapy (CWT) used alone or associated with pedaling to recover from exhaustive exercise. After high-intensity intermittent exercise, 33 participants underwent 30 min of either (i) passive rest (PASSIVE), (ii) CWT with pedaling while in water (COMB) or (iii) classic CWT (CWT). Blood lactate concentration, countermovement jump height and perceived exhaustion were recorded before exercise, immediately after, after recovery interventions and after an additional 30 min of passive rest. Blood lactate concentration returned to initial values after 30 min of COMB (5.9 mmol/L), whereas in the other conditions even 60 min was not enough (10.2 and 9.6 mmol/L for PASSIVE and CWT, respectively, p < 0.05). Jump height was close to initial values after 30 min of CWT (37.3 cm), whereas values were still depressed after 60 min in the PASSIVE (36.0 cm) and COMB (35.7 cm) conditions (p < 0.05). Perceived exertion was still high for all conditions after 60 min. The present results are in favor of the utilization of CWT after exhaustive exercise, but the modality has to be chosen depending on what comes next (subsequent exercise scheduled in the following hours or further away).

Stress responses and baroreflex function in coronary disease.

Exaggerated pressor responses to mental stress in patients with coronary artery disease (CAD) are associated with increased risk for subsequent cardiovascular events. The integrated baroreflex gain and its mechanical and neural component were estimated and then related to the blood pressure and heart rate responses to simulated real-life stressors: mental arithmetic and public speaking. Eighteen healthy individuals (aged 61 +/- 8 yr) and 29 individuals with documented CAD but no other comorbidities (aged 59 +/- 8 yr) were studied. Heart rate and blood pressures were continuously assessed before, during preparation for, and during performance of a math task and a speech task. The assessment of beat-to-beat carotid diameters during baroreflex engagement was used to estimate the integrated baroreflex gain and its mechanical and neural component. The CAD subjects demonstrated significantly greater increases in heart rate and blood pressures for the performance of the speech task. However, there were no group differences in integrated cardiovagal baroreflex gain or either mechanical or neural baroreflex component. These findings indicate that the augmented pressor responses in CAD do not result from a generalized arterial baroreflex deficit.

Feasibility and efficacy of progressive electrostimulation strength training for competitive tennis players.

The purpose of this preliminary study was to show the feasibility of electrostimulation (ES) strength exercise incorporated into tennis sessions during the preparatory season of competitive players, and its impact on anaerobic performance. Twelve tennis players (5 men, 7 women) completed 9 sessions of quadriceps ES (duration: 16 minutes; frequency: 85 Hz; on-off ratio: 5.25-25 seconds) during 3 weeks. The ES sessions were integrated into tennis training sessions. Subjects were baseline tested and retested 1 (week 4), 2 (week 5), 3 (week 6), and 4 weeks (week 7) after the ES training program for maximal quadriceps strength, vertical jump height, and shuttle sprint time. Participants were able to progressively increase ES current amplitude and evoked force throughout the 9 training sessions, with an optimal treatment compliance of 100%. Maximal quadriceps strength significantly increased during the entire duration of the experiment (p < 0.001). Countermovement jump height at week 5 (+5.3%) and week 6 (+6.4%) was significantly higher than at baseline (p < 0.05). In addition, 2 x 10-m sprint time at week 6 was significantly shorter (-3.3%; p = 0.004) compared with pretraining. The 3-week ES strength training program was successfully incorporated into preseason tennis training with a linear progression in all training parameters. Throughout the study period, a delayed enhancement of anaerobic power and stretch-shortening cycle performance was observed. Progressive ES strength training may be safely included in the early tennis season and can lead to improvements in the anaerobic performance of men and women players.

Effect of reflexive activation of motor units on torque development during electrically-evoked contractions of the triceps surae muscle.

The aim of the study was to identify stimulation conditions permitting the occurrence of extra torque (ET) and to examine their impact on spinal and corticospinal excitabilities. Twelve subjects received stimulation trains over the tibial nerve (20 s duration, 1 ms pulse duration) that were delivered at 3 stimulation frequencies (20, 50, and 100 Hz) and at 5 intensities (110%, 120%, 130%, 140%, and 150% of the motor threshold). Torque-time integral (TTI) of each stimulation train was calculated. Spinal [maximum H-reflex (Hmax)/maximal M-wave (Mmax)] and corticospinal [maximal motor evoked potential amplitude (MEPmax)/Mmax] excitabilities were assessed at rest before and after each stimulation train by tibial nerve stimulation and by transcranial magnetic stimulation, respectively. Moreover, a twitch at each stimulation intensity was delivered before and after each stimulation train. The EMG activity associated with this twitch was analyzed to identify the initial motor unit (MU) recruitment pathway before each stimulation train and discriminate trials to H-trials (indirect recruitment) and M-trials (direct recruitment). TTI was higher for H-trials compared with M-trials for all tested frequencies. There was a decrease in Hmax/Mmax for the 20 Hz-H trials and an increase for the 100 Hz-H trials, whereas MEPmax/Mmax remained unchanged at post measurements. Present results demonstrate that the initial MU recruitment pattern plays a main role in the ET occurrence, with the indirect recruitment via the afferent volley being substantial for its development. The modulations of Hmax/Mmax without changes in MEPmax/Mmax suggest that the ET development affects spinal excitability and that these changes are frequency dependent. NEW & NOTEWORTHY This study brings new insights into the stimulation conditions permitting the development of extra torque. An initial indirect recruitment of motor units, inducing reflex activation of spinal neurons through Ia afferent solicitation, appears a prerequisite for extra torque development. Under these conditions, spinal excitability modulations were frequency dependent.

Physical and Psychological Effectiveness of Cardiac Rehabilitation: Age Is Not a Limiting Factor!

BACKGROUND: There is little data regarding the impact of patient age on the physical and psychological effectiveness of cardiac rehabilitation (CR). The aim of the present study was therefore to compare the effects of an exercise-based CR program on physical and psychological parameters in young, old, and very old patients. We also aimed to identify the features that best predicted CR outcome. METHODS: A total of 733 patients were divided into 3 subgroups: YOUNG (< 65 years old), OLD (between 65 and 80 years old), and VERY OLD (≥ 80 years old). Physical variables such as peak workload and estimated peak VO2 as well as psychological variables such as scores of anxiety and depression were evaluated for all patients before and after CR. RESULTS: Performance in all tests and scores for all questionnaires were significantly improved in all patients (P < 0.05). Age was significantly correlated with all the initial values (P < 0.05) but not with post-CR values. In addition, lower initial values of peak workload were associated with larger post-CR improvements irrespective of age. However, higher pre-CR anxiety and depression scores were associated with greater post-CR increases in physical performance in YOUNG and OLD patients, respectively. CONCLUSIONS: CR induced significant improvements of physical and psychological parameters for all patient groups. More interestingly, our results suggest that patients with the greatest physical impairments at baseline would benefit the most from CR, whatever their age. However, the value of initial mental state as a predictor of post-CR improvement depends on the age of the patient.

Low-frequency electric muscle stimulation combined with physical therapy after total hip arthroplasty for hip osteoarthritis in elderly patients: a randomized controlled trial.

OBJECTIVE: To assess the effects of low-frequency electric muscle stimulation associated with usual physiotherapy on functional outcome after total hip arthroplasty (THA) for hip osteoarthritis (OA) in elderly subjects. DESIGN: Randomized controlled trial; pre- and posttreatment measurements. SETTING: Hospital rehabilitation department. PARTICIPANTS: Subjects (N=29) referred to the rehabilitation department after THA for hip OA. INTERVENTIONS: The intervention group (n=16; 78+/-8 y) received simultaneous low-frequency electric muscle stimulation of bilateral quadriceps and calf muscles (highest tolerated intensity, 1h session, 5 d/wk, for 5 weeks) associated with conventional physical therapy including resistance training. The control group (n=13; 76+/-10 y) received conventional physical therapy alone (25 sessions). MAIN OUTCOME MEASURES: Maximal isometric strength of knee extensors, FIM instrument, before and after; a six-minute walk test and a 200 m fast walk test, after; length of stay (LOS). RESULTS: Low-frequency electric muscle stimulation was well tolerated. It resulted in a greater improvement in strength of knee extensors on the operated side (77% vs 23%; P<.01), leading to a better balance of muscle strength between the operated and nonoperated limb. The low-frequency electric muscle stimulation group also showed a greater improvement in FIM scores, though improvements in the walk tests were similar for the 2 groups, as was LOS. CONCLUSIONS: Low-frequency electric muscle stimulation is a safe, well-tolerated therapy after THA for hip OA. It improves knee extensor strength, which is one of the factors leading to greater functional independence after THA.

Do low-frequency electrical myostimulation and aerobic training similarly improve performance in chronic heart failure patients with different exercise capacities?

OBJECTIVE: To confirm that electrical myostimulation is a good alternative to conventional aerobic training in patients with chronic heart failure and to compare the effects of both training programmes in patients with different exercise capacities. PATIENTS AND METHODS: A total of 44 patients with stable chronic heart failure underwent 5 weeks of exercise training, with electrical myostimulation or conventional aerobic training programmes. At baseline and after the training period, patients performed a symptom-limited cardiopulmonary exercise test and a 6-min walk test. RESULTS: Oxygen uptake at the end of exercise (V.O2 peak) and at ventilatory threshold (V.O2 VT) increased after electrical myostimulation (p< 0.001) and conventional aerobic training (p< 0.001) training programmes. The slope of the relationship between V.O2 and workload was reduced after electrical myostimulation (p< 0.05), but not after conventional aerobic training. Recovery was improved after both training programmes (p< 0.05), and the distance walked in 6 min was increased (p< 0.001). These improvements were not statistically different between electrical myostimulation and conventional aerobic training. Moreover, electrical myostimulation induced greater improvements in patients with low exercise capacity, whereas conventional aerobic training induced improved performance in patients with average exercise capacity. CONCLUSION: Five weeks of electrical myostimulation and conventional aerobic training exercise training produced similar improvements in exercise capacity in patients with chronic heart failure. However, electrical myostimulation appears to be more effective in patients with low exercise capacity than in those with average exercise capacity.

An Acute Dose of Specific Grape and Apple Polyphenols Improves Endurance Performance: A Randomized, Crossover, Double-Blind versus Placebo Controlled Study.

Polyphenols are thought to be an interesting ergogenic aid for exercise and recovery. However, most studies regarding the effects of polyphenols investigated several days of supplementations. The present work aimed to study the effects of an acute intake of grape and apple polyphenols on the capacity to maintain intense exercise, here named endurance performance. Forty-eight physically active men (31 ± 6 years) were included in this study. During the two testing sessions, volunteers completed an endurance test at a high percentage of their maximal aerobic power and time to exhaustion was measured. Respiratory and pain parameters were also monitored. The preceding evening and 1 h before testing, volunteers had to absorb either 500 mg of polyphenols or placebo according to randomization. In comparison with the placebo, the mean duration of the maximal endurance test was significantly increased with polyphenols (+9.7% ± 6.0%, p < 0.05). The maximal perceived exertion was reached later with polyphenols (+12.8% ± 6.8%, p < 0.05). Practically, the present study showed the beneficial effects of grape and apple polyphenols for athletes looking for endurance performance improvements. The specifically designed profile of polyphenols appeared to enhance the capacity to maintain intensive efforts and delay perceived exertion.

One year of training with FES has impressive beneficial effects in a 36-year-old woman with spinal cord injury.

CONTEXT: Reductions of muscular and cardiorespiratory functions are often observed in people with spinal cord injury (SCI) and several studies demonstrated the benefits of aerobic and strengthening exercise training for this population. Functional Electrical Stimulation (FES) of paralyzed muscles has been proposed as a strategy to assist patients in executing functional movement but its utilization during long durations has never been investigated. The purpose of the present study was to assess the effects of a one-year training program with FES (strengthening and rowing) in one subject with SCI. Evoked torque, quadriceps muscle thickness, aerobic exercise capacity and bone mineral density were tested. FINDINGS: All parameters increased after training: average evoked torque +151%, quadriceps muscle thickness +136%, thigh circumference +14%, bone density +19%, maximal oxygen uptake +76% and oxygen uptake at ventilatory threshold +111%. CONCLUSION: These impressive improvements demonstrate that FES training offers several interesting clinical benefits in a patient with SCI.

Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles.

This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT.