Provocative mechanical tests of the peripheral nervous system affect the joint torque‐angle during passive knee motion

This study aimed to determine the influence of the head, upper trunk, and foot position on the passive knee extension (PKE) torque‐angle response. PKE tests were performed in 10 healthy subjects using an isokinetic dynamometer at 2°/s. Subjects lay in the supine position with their hips flexed to 90°. The knee angle, passive torque, surface electromyography (EMG) of the semitendinosus and quadriceps vastus medialis, and stretch discomfort were recorded in six body positions during PKE. The different maximal active positions of the cervical spine (neutral; flexion; extension), thoracic spine (neutral; flexion), and ankle (neutral; dorsiflexion) were passively combined for the tests. Visual analog scale scores and EMG were unaffected by body segment positioning. An effect of the ankle joint was verified on the peak torque and knee maximum angle when the ankle was in the dorsiflexion position (P < 0.05). Upper trunk positioning had an effect on the knee submaximal torque (P < 0.05), observed as an increase in the knee passive submaximal torque when the cervical and thoracic spines were flexed (P < 0.05). In conclusion, other apparently mechanical unrelated body segments influence torque‐angle response since different positions of head, upper trunk, and foot induce dissimilar knee mechanical responses during passive extension.     

Effects of hamstring stretching on passive muscle stiffness vary between hip flexion and knee extension maneuvers

The purpose of this study was to examine whether the effects of hamstring stretching on the passive stiffness of each of the long head of the biceps femoris (BFl), semitendinosus (ST), and semimembranosus (SM) vary between passive knee extension and hip flexion stretching maneuvers. In 12 male subjects, before and after five sets of 90 s static stretching, passive lengthening measurements where knee or hip joint was passively rotated to the maximal range of motion (ROM) were performed. During the passive lengthening, shear modulus of each muscle was measured by ultrasound shear wave elastography. Both stretching maneuvers significantly increased maximal ROM and decreased passive torque at a given joint angle. Passive knee extension stretching maneuver significantly reduced shear modulus at a given knee joint angle in all of BFl, ST, and SM. In contrast, the stretching effect by passive hip flexion maneuver was significant only in ST and SM. The present findings indicate that the effects of hamstring stretching on individual passive muscles’ stiffness vary between passive knee extension and hip flexion stretching maneuvers. In terms of reducing the muscle stiffness of BFl, stretching of the hamstring should be performed by passive knee extension rather than hip flexion.     

Acute decrease in the stiffness of resting muscle belly due to static stretching

The purpose of the study was to examine the acute effect of static stretching exercise on the resting stiffness of gastrocnemius muscle belly. Ten healthy young adults performed standing wall stretching in dorsiflexion for 1 min at a time and repeated five times. Before and after stretching, the shear modulus was measured in medial and lateral heads of the resting gastrocnemius muscle with ultrasound shear‐wave elastography. After the stretching, dorsiflexion range of motion (ROM) of the ankle joint increased (P < 0.01) by 3.9° and returned in 20 min. Immediately after stretching, shear modulus decreased (P < 0.01) by 14%, compared with before stretching across muscle heads. The decrease in shear modulus returned in 20 min after stretching. In the comparison group of 10 additional subjects, the standing intervention without stretching had no influence on these measures. There was a negative correlation between dorsiflexion ROM and shear modulus in either head before and after stretching. The results demonstrate the transient decreases in the stiffness of the resting gastrocnemius muscle belly and indicate that joint flexibility is greater in individuals with lower resting stiffness of the muscle belly.     

Viscoelasticity of the muscle–tendon unit is returned more rapidly than range of motion after stretching

The purpose of this study was to clarify the time course of the viscoelasticity of gastrocnemius medialis muscle and tendon after stretching. In 11 male participants, displacement of the myotendinous junction on the gastrocnemius medialis muscle was measured ultrasonographically during the passive dorsiflexion test, in which the ankle was passively dorsiflexed at a speed of 1°/s to the end of the range of motion (ROM). Passive torque, representing resistance to stretch, was also measured using an isokinetic dynamometer. On five different days, passive dorsiflexion tests were performed before and 0, 15, 30, 60 or 90 min after stretching, which consisted of dorsiflexion to end ROM and holding that position for 1 min, five times. As a result, end ROM was significantly increased at 0, 15 and 30 min (P<0.05 each) after stretching as compared with each previous value. Passive torque at end ROM was also significantly increased after stretching. Although the stiffness of the muscle–tendon unit was significantly decreased immediately after stretching (P<0.05), this shift recovered within 15 min. These results showed that the retention time of the effect of stretching on viscoelasticity of the muscle–tendon unit was shorter than the retention time of the effect of stretching on end ROM.     

Hamstring muscle elasticity differs in specialized high-performance athletes

The effect of training on hamstring flexibility has been widely assessed through the measurement of the maximal range of motion or passive torque. However, these global measures do not provide direct information on the passive muscle mechanical properties of individual muscle. This characterization is crucial to better understand the effect of interventions as selective adaptations may occur among synergist muscles. Taking advantage of shear wave elastography, we aimed to determine whether elite sport athletes exhibit different passive shear modulus of hamstring heads compared to controls. Passive shear modulus was measured on semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF) using shear wave elastography with the knee flexed at 60° and 90°, and 90° of hip flexion. A total of 97 elite athletes from various sports including running sprint, figure skating, fencing, field hockey, taekwondo, basketball, and soccer and 12 controls were evaluated. The shear modulus measured at 60° of knee flexion was lower in SM for figure skating (P < .001; d = 1.8), taekwondo (P < .001; d = 2.1), fencing (P = .024; d = 1.0), and soccer (P = .011; d = 0.9) compared to controls, while no difference was found for athletic sprinters, field hockey, and basketball players. Shear modulus of the BF and ST muscle was not significantly different between controls and elite athletes, regardless of the sport specialization (all P values = 1). We provide evidence that the shear modulus of the SM is altered in athletes involved in elite sport practice performed over large range of motion and/or including substantial stretching program in training content (taekwondo, figure skating, fencing, and soccer).     

Effects of warm‐up on hamstring muscles stiffness: Cycling vs foam rolling

This study investigated the effects of active and/or passive warm‐up tasks on the hamstring muscles stiffness through elastography and passive torque measurements. On separate occasions, fourteen males randomly completed four warm‐up protocols comprising Control, Cycling, Foam rolling, or Cycling plus Foam rolling (Mixed). The stiffness of the hamstring muscles was assessed through shear wave elastography, along with the passive torque‐angle relationship and maximal range of motion (ROM) before, 5, and 30 minutes after each experimental condition. At 5 minutes, Cycling and Mixed decreased shear modulus (?10.3% ± 5.9% and ?7.7% ± 8.4%, respectively; P≤.0003, effect size [ES]≥0.24) and passive torque (?7.17% ± 8.6% and ?6.2% ± 7.5%, respectively; P≤.051, ES≥0.28), and increased ROM (+2.9% ± 2.9% and +3.2% ± 3.5%, respectively; P≤.001, ES≥0.30); 30 minutes following Mixed, shear modulus (P=.001, ES=0.21) and passive torque (P≤.068, ES≥0.2) were still slightly decreased, while ROM increased (P=.046, ES=0.24). Foam rolling induced “small” immediate short‐term decreases in shear modulus (?5.4% ± 5.7% at 5 minutes; P=.05, ES=0.21), without meaningful changes in passive torque or ROM at any time point (P≥.12, ES≤0.23). These results suggest that the combined warm‐up elicited no acute superior effects on muscle stiffness compared with cycling, providing evidence for the key role of active warm‐up to reduce muscle stiffness. The time between warm‐up and competition should be considered when optimizing the effects on muscle stiffness.     

The role of neural tension in hamstring flexibility

Resistance to stretch, electromyographic (EMG) response to stretch, stretch discomfort and maximum range of motion (ROM) were measured during passive hamstring stretches performed in the slump test position (neural tension stretch) and in the upright position (neutral stretch) in eight healthy subjects. Stretches were performed on an isokinetic dynamometer at 5°/s with the test thigh flexed 40° above the horizontal, and the seat back at 90° to the horizontal. Surface EMG signals were recorded from the medial and lateral hamstrings during stretches. Knees were passively extended to maximum stretch tolerance with test order (neural tension vs neutral) alternated between legs. For neural tension stretches, the cervical and thoracic spine were manually flexed. Maximum ROM was 8° less for the neural tension stretch vs the neutral stretch (P<0.01). Resistance to stretch was 14–15% higher for the neural tension stretch vs the neutral stretch (P<0.001) at common joint angles in the final third of ROM. Stretch discomfort and EMG response were unaffected by neural tension. In conclusion, an increased passive resistance to stretch with the addition of neural tension during passive hamstring stretch despite no change in the EMG response indicates that passive extensibility of neural tissues can limit hamstring flexibility.     

Increase in passive muscle tension of the quadriceps muscle heads in jumping athletes with patellar tendinopathy

To investigate the passive muscle tension of the quadriceps muscle heads in male athletes clinically diagnosed with patellar tendinopathy (PT) with those of healthy controls and explore the interplay between passive muscle tension and patellar tendon stiffness. Between November 2012 and December 2013, 66 male athletes (mean age of 21.1 ± 4.4 years) were examined using supersonic shear wave imaging technology. The passive tension of the vastus lateralis (VL) and rectus femoris (RF) muscles and patellar tendon stiffness were assessed. The shear elastic modulus of the VL muscle was increased by 26.5% (P < 0.001) in the subjects with PT when compared with the controls. Greater passive tension in the VL was associated with higher patellar tendon stiffness (r = 0.38; P = 0.001). The vastus lateralis muscle of the quadriceps shows increase in passive muscle tension in jumping athletes with patellar tendinopathy. These findings suggest that increase in muscle tension is not similar in the individual muscles of the quadriceps muscle. Traditional stretching of the whole quadriceps muscle might not be targeted to the tight muscle heads.     

The influence of ankle joint movement on knee joint kinesthesia at various movement velocities

The purpose of this study was to determine if gastrocnemius elongation or shortening and direction and velocity of knee movement influenced knee kinesthesia. Healthy volunteers sat with their knee flexed (20°) and was then passively rotated (flexion or extension) at three velocities (0.5, 2, or 10°/s) while the ankle was either fixed or rotated (dorsiflexed or plantar flexed at 0.17, 0.65, or 3.3°/s) creating gastrocnemius elongation or shortening. Subjects activated a thumb switch, stopping motion once they detected onset and direction of the motion. Detection of passive movement sense (DPMS) was the angular movement before activation of a thumb‐switch. Significant differences (P=0.003) in the rate of change in DPMS across a variety of movement velocities was observed but shortening or elongation of the gastrocnemius did not affect DPMS. Gastrocnemius elongation/shortening did not affect knee DPMS, simple reaction time plays an important role in testing kinesthesia especially at faster movements. While feedback from the gastrocnemius muscle plays a limited role in healthy subjects, differences in testing velocities may incorporate higher levels of central nervous system processing. Clinical measures of kinesthesia can be affected by both movement direction and movement velocity that are speed dependent.     

Effect of ankle taping on angle and force matching and strength of the plantar flexors

ObjectiveInvestigate the effect of ankle taping on plantar-flexion strength, angle matching and force matching.DesignSingle group, repeated measures.SettingLaboratory of an educational institution.ParticipantsTwenty uninjured females (22.9 ± 3.6 years).Main Outcome MeasuresTape was applied to the ankle using a conventional hindfoot technique. Angle and force matching, and plantar-flexor strength were assessed using the purpose built dual ankle dynamometer, and measures were taken prior to and following taping. Angle matching was assessed passively and actively at 10, 15 and 20° of plantar-flexion. Participants were required to match the angle of the reference leg with the contralateral leg. Force matching was assessed at 10° of plantar-flexion and participants matched the torque of the reference leg with the contralateral leg.ResultsTaping had no effect on absolute errors during active or passive angle matching. Regardless of taping, the ankle angle tested had a significant effect on passive angle matching (p < 0.001); subjects were most accurate at matching a plantar-flexion angle of 20°. Ankle taping had no effect on force matching. Taping significantly improved peak plantar-flexion strength by 20% (p = 0.028).ConclusionAnkle taping has little effect on contralateral force and angle matching, but it can enhance peak plantar-flexion strength.     

Effects of muscle activation on shear between human soleus and gastrocnemius muscles

Lateral connections between muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) muscles. We hypothesized that selective activation of LG would decrease the stretch‐induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL muscle fascicle lengths and relative displacement of aponeuroses between the muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both passive conditions and with selective electrical stimulation of LG. During active stretch, plantar flexion force was 22% greater (P < 0.05) and relative displacement of aponeuroses was smaller than during passive stretch (P < 0.05). Soleus fascicle length changes did not differ between passive and active stretches but LG fascicles stretched less in the active than passive condition when the stretch began at angles of 70° and 90° of knee flexion (P < 0.05). The activity‐induced decrease in the relative displacement of SOL and LG suggests stronger (stiffer) connectivity between the two muscles, at least at flexed knee joint angles, which may serve to facilitate myofascial force transmission.     

Interaction of foot and hip factors identifies Achilles tendinopathy occurrence in recreational runners

ObjectivesTo investigate the interaction of ankle-foot complex and hip joint factors with Achilles Tendinopathy (AT) occurrence in recreational runners.DesignCross-sectional.SettingResearch Laboratory.Participants51 runners, 26 healthy and 25 with AT.Main outcomes measuresShank-forefoot alignment (SFA), weight bearing lunge test (WBLT), passive hip internal rotation (IR) range of motion (ROM), hip external rotators (ER) and ankle plantar flexors (PF) isometric strength. CART analyses were performed to assess interactions that could distinguish those with AT.ResultsPassive hip IR ROM, ankle PF torque, SFA, and hip ER isometric torque were associated AT occurrence. The model correctly classified 92% of individuals without AT and 72% of those with AT. The area under the receiver operating characteristic curve was 0.88. Interaction factors revealed in nodes 3 and 10 were statistically significant. In node 3, runners with more than 29.33° of passive hip IR ROM had a 130% increased likelihood (PR = 2.30) of AT. Node 10 showed that individuals with higher PF torque, SFA varus, ER torque, but reduced passive hip IR ROM had an 87% increased likelihood (PR = 1.87) of AT.ConclusionInteractions between hip and foot factors could accurately classify recreational runners with and without AT.     

Foot kinematics and leg muscle activation patterns are altered in those with limited ankle dorsiflexion range of motion during incline walking

BackgroundLarger ankle dorsiflexion (DF) is required when walking on inclined surfaces. Individuals with limited DF range of motion (ROM) may experience greater tissue stress on sloped surfaces and walk in altered gait patterns compared to the those with normal DF ROM.Research questionWould the individuals with limited DF ROM walk with distinctive ankle DF patterns compared to those with normal DF ROM on the inclined surfaces?MethodsTen Limited DF ROM (passive ROM=35.3 ± 2.7°) and nine Normal DF ROM (passive ROM=46.4 ± 4.2°) participants walked on a treadmill at five slope angles (0°, 5°, 10°, 15°, 20°) for 2 min at a self-selected speed. The peak DF angles and the peak myoelectric activity levels of the tibialis anterior (TA) and soleus (SOL) muscles were quantified during the swing and stance phases of each walking trial, and they were compared between the two groups.ResultsParticipants with limited DF ROM walked with smaller peak DF (3.1° at 0° slope ~ 8.4° at 20° slope) and greater peak TA activity in swing than those of the Normal ROM participants (3.4° ~ 12.2°), with significant differences at 20° slope. The peak DF angle in stance (Limited: 9.6° ~ 19.0°; Normal: 10.1° ~ 21.0°) did not differ between the two groups at all slopes, but the peak activity of the SOL muscle was significantly greater for the Limited group at slopes of 10° and higher.SignificanceStudy results indicate that incline walking could be more challenging to the individuals with limited DF ROM as they need to approach and push-off the sloped surfaces with more efforts of the dorsiflexor and the plantar flexor muscles, respectively. Prolonged walking on inclined surfaces may produce faster development of muscle fatigue or tissue damage than those with normal DF ROM.     

Effect of PNF stretching training on the properties of human muscle and tendon structures

The purpose of this study was to investigate the influence of a 6‐week proprioceptive neuromuscular facilitation (PNF) stretching training program on the various parameters of the human gastrocnemius medialis muscle and the Achilles tendon. Therefore, 49 volunteers were randomly assigned into PNF stretching and control groups. Before and after the stretching intervention, we determined the maximum dorsiflexion range of motion (RoM) with the corresponding fascicle length and pennation angle. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) of the musculo‐articular complex were measured with a dynamometer. Muscle‐tendon junction (MTJ) displacement allowed us to determine the length changes in tendon and muscle, and hence to calculate stiffness. Mean RoM increased from 31.1 ± 7.2° to 33.1 ± 7.2° (P = 0.02), stiffness of the tendon decreased significantly in both active (from 21.1 ± 8.0 to 18.1 ± 5.5 N/mm) and passive (from 12.1 ± 4.9 to 9.6 ± 3.2 N/mm) conditions, and the pennation angle increased from 18.5 ± 1.8° to 19.5 ± 2.1° (P = 0.01) at the neutral ankle position (90°), only in the intervention group, whereas MVC and PRT values remained unchanged. We conclude that a 6‐week PNF stretching training program increases RoM and decreases tendon stiffness, despite no change in PRT.     

Cryotherapy induces an increase in muscle stiffness

Although cold application (ie, cryotherapy) may be useful to treat sports injuries and to prevent muscle damage, it is unclear whether it has adverse effects on muscle mechanical properties. This study aimed to determine the effect of air‐pulsed cryotherapy on muscle stiffness estimated using ultrasound shear wave elastography. Myoelectrical activity, ankle passive torque, shear modulus (an index of stiffness), and muscle temperature of the gastrocnemius medialis were measured before, during an air‐pulsed cryotherapy (−30°C) treatment of four sets of 4 minutes with 1‐minute recovery in between and during a 40 minutes postcryotherapy period. Muscle temperature significantly decreased after the second set of treatment (10 minutes: 32.3±2.5°C; P <.001), peaked at 29 minutes (27.9±2.2°C; P <.001) and remained below baseline values at 60 minutes (29.5±2.0°C; P <.001). Shear modulus increased by +11.5±11.8% after the second set (10 minutes; P =.011), peaked at 30 minutes (+34.7±42.6%; P <.001), and remained elevated until the end of the post‐treatment period (+25.4±17.1%; P <.001). These findings provide evidence that cryotherapy induces an increase in muscle stiffness. This acute change in muscle mechanical properties may lower the amount of stretch that the muscle tissue is able to sustain without subsequent injury. This should be considered when using cryotherapy in athletic practice.     

Effect of isokinetic training on strength,functionality and proprioception in athletes with functional ankle instability

The purpose of this study was to investigate the effects of isokinetic exercise on strength, joint position sense and functionality in recreational athletes with functional ankle instability (FAI). Strength, proprioception and balance of 24 recreational athletes with unilateral FAI were evaluated by using isokinetic muscle strength measurement, ankle joint position sense and one leg standing test. The functional ability was evaluated using five different tests. These were; single limb hopping course (SLHC), one legged and triple legged hop for distance (OLHD–TLHD), and six and cross six meter hop for time (SMHT–CSMHT). Isokinetic peak torque of the ankle invertor and evertor muscles were assessed eccentrically and concentrically at test speeds of 120°/s. Isokinetic exercise protocol was carried out at an angular velocity of 120°/s. The exercise session was repeated three times a week and lasted after 6 weeks. At baseline, concentric invertor strength was found to be significantly lower in the functionally unstable ankles compared to the opposite healthy ankles (p < 0.001). This difference was not present after executing the 6 weeks exercise sessions (p > 0.05). Ankle joint position sense in the injured ankles declined significantly from 2.35 ± 1.16 to 1.33 ± 0.62° for 10° of inversion angle (p < 0.001) and from 3.10 ± 2.16 to 2.19 ± 0.98° for 20° of inversion angle (p < 0.05) following the isokinetic exercise. One leg standing test score decreased significantly from 15.17 ± 8.50 to 11.79 ± 7.81 in the injured ankles (p < 0.001). Following the isokinetic exercise protocol, all of the worsened functional test scores in the injured ankles as compared to the opposite healthy ankles displayed a significant improvement (p < 0.01 for OLHD and CSMHT, p < 0.001 for SLHC, TLHD, and SMHT). These results substantiate the deficits of strength, proprioception, balance and functionality in recreational athletes with FAI. The isokinetic exercise program used in this study had a positive effect on these parameters.     

Specialized properties of the triceps surae muscle‐tendon unit in professional ballet dancers

This study compared professional ballet dancers (n = 10) to nonstretching controls (n = 10) with the purpose of comparing muscle and tendon morphology, mechanical, neural, and functional properties of the triceps surae and their role for ankle joint flexibility. Torque‐angle and torque‐velocity data were obtained during passive and active conditions by use of isokinetic dynamometry, while tissue morphology and mechanical properties were evaluated by ultrasonography. Dancers displayed longer gastrocnemius medialis fascicles (55 ± 5 vs 47 ± 6 mm) and a longer (207 ± 33 vs 167 ± 10 mm) and more compliant (230 ± 87 vs 364 ± 106 N/mm) Achilles tendon compared to controls. Greater passive ankle dorsiflexion range of motion (40 ± 7 vs 17 ± 9°) was seen in dancers, resulting from greater fascicle strain and greater elongation of the muscle. Peak electromyographic (EMG ) activity recorded during passive stretching was lower in dancers, and at common joint angles, dancers displayed lower EMG amplitude and lower passive joint stiffness. No differences between groups were seen in maximal isometric plantar flexor torque, isokinetic peak torque, angle of peak torque, or work. In conclusion, the greater ankle joint flexibility of professional dancers seems attributed to multiple differences in morphological and mechanical properties of muscle and tendinous tissues, and to factors related to neural activation.     

Effects of plyometric training on passive stiffness of gastrocnemii and the musculo‐articular complex of the ankle joint

This study aimed to determine simultaneously the effects of plyometric training on the passive stiffness of the ankle joint musculo‐articular complex, the gastrocnemii muscle–tendon complex (MTC) and the Achilles tendon in order to assess possible local adaptations of elastic properties. Seventeen subjects were divided into a trained (TG) group and a control (CG) group. They were tested before and after 8 weeks of a plyometric training period. The ankle joint range of motion (RoM), the global musculo‐articular passive stiffness of the ankle joint, the maximal passive stiffness of gastrocnemii and the stiffness of the Achilles tendon during isometric plantar flexion were determined. A significant increase in the jump performances of TG relative to CG was found (squat jumps: +17.6%, P=0.008; reactive jumps: +19.8%, P=0.001). No significant effect of plyometric training was observed in the ankle joint RoM, musculo‐articular passive stiffness of the ankle joint or Achilles tendon stiffness (P>0.05). In contrast, the maximal passive stiffness of gastrocnemii of TG increased after plyometric training relative to CG (+33.3%, P=0.001). Thus, a specific adaptation of the gastrocnemii MTC occurred after plyometric training, without affecting the global passive musculo‐articular stiffness of the ankle joint.     

Spatial-temporal parameters,pelvic and lower limb movements during gait in individuals with reduced passive ankle dorsiflexion

BackgroundProper ankle dorsiflexion range of motion (ADF-ROM) allows the anterior roll of the tibia relative to the foot during the midstance phase of gait, which contributes to forward movement of the body. Individuals with reduced passive ADF-ROM may present altered movement patterns during gait due to an inefficient anterior tibial roll over the support foot during the stance phase.Research question: What is the influence of reduced passive ADF-ROM on the pelvic and lower limb movements and spatiotemporal parameters during gait?MethodThirty-two participants divided into two groups according to the degree of passive ADF-ROM—less than 10° (lower ADF-ROM group) or greater than 15° (higher ADF-ROM group) —were subjected to gait assessment using a three-dimensional motion analysis system. Independent t-tests were used to compare the pelvic and lower limb movements and spatiotemporal gait parameters between the groups on this cross-sectional study.ResultsThe lower ADF-ROM group had shorter step length, lower peak of pelvic ipsilateral rotation angle, and lower hip and knee maximum flexion angles in the stance phase (p < 0.05). In addition, the peaks of the ankle and forefoot-rearfoot dorsiflexion angles were smaller in the reduced ADF-ROM group (p < 0.05). The between-group differences presented effect sizes varying from moderate to large.SignificanceIndividuals with reduced passive ADF-ROM presented reduced foot and ankle dorsiflexion, knee and hip flexion, and pelvis rotation movements and shorter step length during gait. However, no differences in foot pronation were noted between groups. Therefore, individuals with reduced passive ADF-ROM present alterations in the lower limb and pelvic movements during gait.     

Dynamic stretching is not detrimental to neuromechanical and sensorimotor performance of ankle plantarflexors

The acute effects of two dynamic stretching (DS) protocols on changes in the ankle range of motion (RoM), neuromechanical, and sensorimotor properties of the plantarflexor muscle group were examined. Eighteen participants received slow (SDS) or fast dynamic stretching (FDS) on two separate days. Outcome measures were assessed pre‐ and 2 minutes post‐interventions, and included maximum dorsiflexion angle, maximum isometric torque at neutral ankle position, maximum concentric and eccentric torques, force matching capacity, joint position sense and medial gastrocnemius muscle and tendon strain. Possibly and likely small increases in dorsiflexion RoM were observed after SDS (mean ± 90% confidence intervals; 1.8 ± 1.2°) and FDS (2.1 ± 1.2°), respectively. Very likely moderate decreases in muscle strain after SDS (?38.0 ± 20.6%) and possibly small decrease after FDS (?13.6 ± 21.2%) were observed. SDS resulted in a likely beneficial small increase in tendon strain (25.3 ± 29.7%) and a likely beneficial moderate increase after FDS (41.4 ± 44.9%). Effects on strength were inconsistent. Possibly small effect on positional error after SDS (?27.1 ± 37.5%), but no clear effect after FDS was observed. Both DS protocols increased RoM, and this was more due to an increase in tendon elongation rather than the muscle. However, SDS showed greater improvement than FDS in both neuromechanical and sensorimotor performance, and hence, SDS can be recommended as part of warm‐up in sporting contexts.