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Analysis of the countermovement jump (CMJ) force-time curve phases provides insight into athlete neuromuscular function and methods by which jump height improves in response to training. A CMJ phase analysis and the dynamic strength index (DSI) have yet to be explored in athletes with cerebral palsy (CP). This study aimed to address this knowledge gap. Eleven state- to international-level athletes with CP completed a pre-post maximal strength training intervention with waitlist control. CMJ was assessed via force plate pre/post baseline and after the 12-week intervention. Following the intervention, CMJ height, takeoff velocity, and concentric phase peak and mean force, impulse and mean acceleration improved significantly (

Task-specific auditory training can improve sensorimotor processing times of the auditory reaction time (RT). The majority of competitive swimmers do not conduct habitual start training with the electronic horn used to commence a race. We examined the effect of four week dive training interventions on RT and block time (BT) of 10 male adolescent swimmers (age 14.0 ± 1.4 years): dive training with auditory components (speaker and electronic horn) (

Fleeton, JRM, Sanders, RH, and Fornusek, C. Strength training to improve performance in athletes with cerebral palsy: A systematic review of current evidence. J Strength Cond Res 34(6): 1774-1789, 2020-Persons with cerebral palsy (CP) can partake in many different forms of organized sport including elite competition at state and international levels. There is limited evidence on how CP athletes should train to enhance performance. The purposes of this article were to conduct a systematic review of the current evidence on ambulatory individuals with CP for (a) strength and functional improvement through strength training; (b) potential sports performance improvement through strength training; (c) the identification of risk and special considerations associated with strength and conditioning for this population, and; (d) the identification of future research foci to educate strength and conditioning coaches on specific program design for elite CP athletes. Seven electronic databases were searched for studies investigating resistance training interventions. The databases were also searched for training interventions or investigations into sports performance in athletes with CP competing at regional level or above. Thirty articles were included in the systematic review of strength training, and 23 articles included in the narrative review of training for sports performance. High-quality evidence indicates that resistance training can improve muscular strength in individuals with CP, with some preliminary evidence of structural and neurological adaptations. However, there is limited evidence for functional improvements. Limited research has examined the performance capacity of athletes with CP, and no training interventions have been conducted. Coaches should employ existing guidelines when designing programs while considering specific athlete limitations. Initially, the focus should be increasing athlete muscular strength before considering specific sport demands.

This systematic review with a meta-analysis of studies was carried out to evaluate the potential of overwork weakness on the basis of grip strength of dominant and nondominant hands in individuals with Charcot-Marie-Tooth disease (CMT). Numerous electronic databases were searched from the earliest records to February 2016. Studies of any design including participants older than 18 years of age with a confirmed diagnosis of CMT that measured grip strength of both hands using dynamometric testing were eligible for inclusion. Of 12 593 articles identified following removal of duplicates, five articles fulfilled the criteria. A total of 166 participants, mostly with CMT1 or CMT2, were described from the studies included. Hand and finger pinch grip strength for the dominant compared with the nondominant hand was not statistically different. There is no definitive evidence that preferential use of the dominant hand in CMT impairs function relative to the nondominant hand. Thus, robust exercise trials of progressive resistance training are needed to understand the extent of adaptations possible and provide evidence of the safety of such regimens.

Previous research has shown that kettlebell swings (KBS), utilizing the hip-hinge technique, exhibit similar lower-limb muscle activation patterns to sprint running. This study investigated whether the inclusion of KBS in the warm-up enhances sprint performance. Moderately trained males (n = 12) and females (n = 8) performed KBS and a control (CON) condition (passive rest) in random order before performing three 20-m sprint trials separated by 4 minutes. No condition (KBS versus CON) effects, time effects or condition by time interactions were found for sprint times at 5-m and 10-m. A significant time effect was found for sprint time at 20-m with faster sprint time at 12 minutes compared to 4 minutes (p = 0.022). No condition effect or condition by time interaction was found for sprint time at 20-m. Small to moderate correlations were found for change in sprint time (CON minus KBS) and KBS load at 4, 8, and 12 minutes. It appears the KBS is not effective for potentiating 20-m sprint performance, however, any potential benefit from the inclusion of KBS as a preconditioning exercise for sprinting may be influenced by individual strength capabilities with KBS.

Aim: Functional electrical stimulation (FES) is a technology that can be used on paralyzed muscles to allow them to move. It has been used in populations with muscle paralysis or weakness for exerc...

The aim of this study was to investigate the effect of neuromuscular electrical stimulation burst duty cycle (BDC) and current type (sinusoidal alternating current [sAC] vs. rectangular alternating current [rAC]) on the electrically induced isometric torque (EIT) and discomfort. Pulsed current (PC) stimulation, which corresponds to one pulse rAC, was included in testing.A repeated-measures design was used. The left quadriceps of 22 healthy subjects (mean ± SD age, 33 ± 8 yrs) were stimulated alternately with sAC and rAC current bursts (4-kHz carrier frequency; 71 bursts per second burst frequency) to produce isometric contractions. A range of BDCs were tested for sAC (7%-50%) and rAC (2%-18%) stimulation at fixed intensities while EIT and discomfort were recorded. BDC presentation order was randomized.Overall, both current types elicited peak EIT at ∼14% BDC (range, 7%-21%). Significantly more EIT was produced by rAC than by sAC stimulation (P0.005). Discomfort increased with BDC and was similar for both current types.The study confirmed previous findings that conventional sAC stimulation (50% BDC) and pulsed current stimulation (rAC with 2% BDC) used in sports and rehabilitation produce similar EIT levels. However, rAC stimulation at low BDC (7%-18%) was more effective (+35% torque produced with similar discomfort) than pulsed current or conventional sAC.

Objective: To investigate the feasibility of neuromuscular electrical stimulation cycling modified to suit persons with advanced multiple sclerosis. Subjects: Eight women with secondary progressive multiple sclerosis. Methods: Subjects participated in an 18-session (40 min) neuromuscular electrical stimulation cycling program. A pedaling cadence of 10 rev•min-1 was employed and stimulation intensity was not modulated to control cadence, but increased gradually throughout each session. The outcomes included the stimulation intensity tolerated, thigh circumference changes, and power output and cardiorespiratory response during cycling. Participants were interviewed about perceived benefits of the treatment including changes in transfer ability. Results: Seven participants (Expanded Disability Status Scale 6.5–8.5) (mean 7.4 (standard deviation 0.7)) completed the training program over an average of 10 weeks. Greater stimulation intensities were tolerated than previously reported for persons with multiple sclerosis. Increases were found in thigh volume. Perceived benefits included improvements in transfer ability, leg circulation, spasticity and strength. Conclusion: Modifying neuromuscular electrical stimulation cycling allowed persons with advanced multiple sclerosis to tolerate greater stimulation intensities and exercise their muscles more intensely than previous studies. The benefits reported, which were solely due to neuromuscular electrical stimulation cycling, demonstrate that persons with preserved sensation and muscle paralysis/paresis might benefit from neuromuscular electrical stimulation exercise when it is adjusted appropriately.

This study compared acute exercise responses during arm cranking, functional electrical stimulation (FES)-assisted leg cycling, and combined arm and leg ("hybrid") cycling in individuals with spinal cord injury during maximal and submaximal exercise.Nine male subjects with long-standing neurological lesions from C7 to T12 were recruited. All subjects performed arm crank ergometry (ACE), FES leg cycle exercise (FES-LCE), combined ACE + FES-LCE, and cycling on a hybrid FES tricycle (HYBRID). They were assessed for their peak exercise responses in all four modalities. Subsequently, their submaximal heart rates (HR), cardiac outputs (Q), stroke volumes (SV), and arteriovenous oxygen extractions (Ca-Cv)O2 were measured at 40%, 60%, and 80% of mode-specific V˙O2peak.Arm exercise alone and arm + leg exercise resulted in significantly higher V˙O2peak and HRpeak compared with FES-LCE (P0.05). Submaximal V˙O2 during FES-LCE was significantly lower than all other modalities across the range of exercise intensities (P0.05). ACE elicited 70%-94% higher steady-state V˙O2, and HYBRID evoked 99%-148% higher V˙O2 compared with FES-LCE. Steady-state FES-LCE also produced significantly lower Q, HR, and (Ca-Cv)O2. ACE evoked 31%-36% higher Q and 19%-47% greater HR than did FES-LCE. HYBRID elicited 31%-49% greater Q and 23%-56% higher HR than FES-LCE.Combined arm and leg exercise can develop a higher oxygen uptake and greater cardiovascular demand compared with ACE or FES-LCE alone. These findings suggested that combined arm + leg FES training at submaximal exercise intensities may lead to greater gains of aerobic fitness than would arm exercise alone. These data also proffered that FES leg cycling exercise by itself may be insufficient to promote aerobic fitness in the spinal cord injury population.

This study examined the effect of dietary supplementation with inorganic nitrate ([Formula: see text] ) on markers of contractile function in human knee extensors. In a double-blinded, randomized cross-over design, 18 (12 M) healthy participants undertook four days of supplementation with either nitrate-rich beetroot juice (NITRATE; days 1-3: 525 mg [Formula: see text], day 4: 1050 mg [Formula: see text]) or nitrate-depleted beetroot juice (PLACEBO). On the fourth day, isometric knee extension force was assessed during a series of voluntary and electrically evoked (stimulation) tests. In addition, muscular fatigue was examined in two separate continuous-stimulation (0.8 s tetanus with a 1:1 work:rest ratio for 102.4 s) fatigue tests, one with and one without blood flow restriction. There were no differences for maximum voluntary contraction, peak twitch force, half-relaxation time and the force-frequency relationship for stimulations up to 100 Hz between the NITRATE and PLACEBO trials. No differences between trials were observed in the non-restricted fatigue test, however NITRATE was found to attenuate the decline in force during the restricted test, such that the force at the 80 s mark (PLACEBO: 66 ± 11 vs. NITRATE 74 ± 9% of initial force; P = .01) and 102 s mark (PLACEBO: 47 ± 8% vs. NITRATE 55 ± 8%; P .01) were significantly higher. These results suggest that four days of [Formula: see text] supplementation elicits peripheral responses in muscle that attenuate muscular fatigue during exhaustive exercise under hypovolemic conditions. This ergogenic action is likely attributable to improved Ca(2+) handling in the muscle, or enhanced perfusion during ischemia.

This study analysed external power output and physiologic responses in 5 individuals with paraplegia during 40 minutes of electrical stimulation leg cycle exercise. Cycling was performed on a motor-driven isokinetic ergometer that enabled precise determinations of power output. Electrical stimulation was increased to 120-140 mA within the first 5 minutes and remained constant thereafter. Power output increased to 10.7 +/- 3.0 W after 2 minutes, dropped to 5.3 +/- 1.8 W after 6 minutes and subsequently recovered to 8.2 +/- 2.2 and 6.1 +/- 2.3 W after 19.5 and 40 minutes, respectively. Oxygen consumption increased to 0.47 +/- 0.09 l/min after 6 minutes and declined during the second half of the exercise bout. Gross mechanical efficiency after 19.5 minutes was elevated compared with the value after 6 minutes. Heart rate was significantly increased at the end of the trial. The time-dependent variability of power output and physiological responses question the concept of steady state for this form of exercise.

Objective To investigate the long-term effects of functional electrical stimulation (FES)-evoked cycle training cadence on leg muscle hypertrophy and electrically evoked strength. Design Open intervention study. Setting Laboratory setting. Participants Untrained individuals with chronic spinal cord injury (N=8). Interventions Six weeks (3d/wk) of training on an isokinetic FES cycle ergometer. For each subject, 1 leg was randomly allocated to cycling at 10 revolutions per minute (rpm) (LOW) for 30min/d, and the other cycling at 50rpm (HIGH) for 30min/d. Main Outcome Measures Pre- and posttraining measurements of lower limb circumference were performed at the distal and middle position of each thigh. Electrically evoked quadriceps muscle torque during an isometric contraction was also assessed. Results Six weeks of FES cycle training significantly increased thigh girth in both LOW and HIGH groups. At midthigh, girth increases induced by LOW (6.6%±1.2%) were significantly greater than those by HIGH (3.6%±0.8%). LOW also produced greater gains in electrically evoked isometric torque than HIGH after training. Conclusions These results suggest that lower pedaling cadences evoke greater muscle hypertrophy and electrically stimulated muscle strength compared with higher cadences.

Fornusek C, Davis GM, Baek I. Stimulation of shank muscles during functional electrical stimulation cycling increases ankle excursion in individuals with spinal cord injury. Objective To investigate the effect of shank muscle stimulation on ankle joint excursion during passive and functional electrical stimulation (FES) leg cycling. Design Within-subject comparisons. Setting Laboratory setting. Participants Well-trained FES cyclists (N=7) with chronic spinal cord injuries. Interventions Two experimental sessions were performed on an isokinetic FES cycle ergometer with a pedal boot that allowed the ankle to plantarflex and dorsiflex during cycling. During the first session, the optimal stimulation timings to induce plantarflexion and dorsiflexion were investigated by systematically altering the stimulation angles of the shank muscles (tibialis anterior [TA] and triceps surae [TS]). During the second session, TA and TS stimulation was included with standard FES cycling (quadriceps, hamstrings, and gluteals) for 6 subjects. Main Outcome Measures Ankle, knee, and hip movements were analyzed using 2-dimensional video. Results The ankle excursions during passive cycling were 19°±6°. TA and TS stimulation increased ankle joint excursion up to 33°±10° and 27°±7°, respectively. Compared with passive cycling, ankle joint excursion was not significantly increased during standard FES cycling (24°±7°). TA and TS stimulation significantly increased the ankle excursion when applied during standard FES cycling (41°±4°). Conclusions Freeing the ankle joint to rotate during FES cycling was found to be safe. The combination of shank muscle stimulation and repetitive ankle joint movement may be beneficial for improving ankle flexibility and leg conditioning. Further research is required to test and design ankle supports that might maximize the benefits of shank muscle activation.

Fornusek C, Davis GM. Cardiovascular and metabolic responses during functional electric stimulation cycling at different cadences. Objective To determine the influence of pedaling cadence on cardiorespiratory responses and muscle oxygenation during functional electric stimulation (FES) leg cycling. Design Repeated measures. Setting Laboratory. Participants Nine subjects with T4 through T10 spinal cord injury (SCI) (American Spinal Injury Association grade A). Interventions FES cycling was performed at pedaling cadences of 15, 30, and 50 revolutions per minute (rpm). Main Outcome Measures At each cadence, heart rate, oxygen uptake, and cardiac output were recorded during 35 minutes of cycling. Near infrared spectroscopy was used to quantify quadriceps muscle oxygenation. Results All pedaling cadences induced similar elevations in cardiorespiratory metabolism, compared with resting values. Higher average power output was produced at 30rpm (8.2±0.7W, P P P Conclusions Cardiorespiratory responses and muscle metabolism adjustments during FES leg cycling were independent of pedal cadence. FES cycling at a cadence of 50rpm may not confer any advantages over 30 or 15rpm for cardiovascular fitness promotion in persons with SCI.

Szecsi J, Fornusek C, Krause P, Straube A. Low-frequency rectangular pulse is superior to middle frequency alternating current stimulation in cycling of people with spinal cord injury. Objective To determine the efficacy of using modulated middle frequency alternating current (MFAC) muscle stimulation for functional electric stimulation–propelled cycling by people with spinal cord injury (SCI) compared with the conventional method of using standard low-frequency rectangular pulses (LFRP). Design Repeated-measures. Setting Laboratory setting. Participants Eleven otherwise healthy volunteer subjects with SCI (8 with American Spinal Injury Association [ASIA] grade A, 3 with ASIA grade B). Interventions To evaluate cycling-relevant differences between LFRP and modulated MFAC stimulation, we exposed participants to isometric measurements and cycling experiments performed during both 20Hz LFRP and 4KHz modulated with 50Hz MFAC. Main Outcome Measures We recorded maximal isometric torque, maximal dynamic work during 20 minutes of ergometer cycling, and perceived discomfort for each of the 2 stimulation patterns. Results Both the isometric torque ( P P Conclusions Our findings suggest that in SCI subjects, stimulated cycling with low frequency is generally more effective than cycling with modulated MFAC in terms of torque, work, and pain sensation.

Objective: This study investigated the effect of pedal cadence upon torque production, power output and muscle fatigue rates during functional electrical stimulation evoked cycling in spinal cord injured individuals. Subjects: All subjects had complete thoracic spinal cord injuries T4–T9 (ASIA A) and had been functional electrical stimulation training regularly for at least 6 months. Methods: One trial (n = 8) examined a low vs high pedal rate (20 and 50 rev min 1 ) upon isolated muscle fatigue over 5 minutes. A second trial (n = 9) investigated the effect of cadence (15 vs 50 rev min 1 ) upon performance during 35-minutes of functional electrical stimulation evoked cycling. Results: Peak torque produced by left quadriceps decayed significantly faster at the higher pedal cadence, indicating a higher rate of muscle fatigue. Functional electrical stimulation cycling over 35 minutes also revealed that peak and average torques were significantly greater at the lower cadence. From 15 minutes onwards, power output was significantly higher at 50 rev min 1 FES-cycling, compared with 15 rev min 1 . Conclusion: The higher muscle forces observed during low cadence functional electrical stimulation cycling should offer improvements over traditional pedalling velocities for training leg strength in individuals with spinal cord injury.