A review of the acute effects of static and dynamic stretching on performance

Does clinically measured ankle plantar flexor muscle strength or weakness correlate with walking performance in healthy individuals?

OBJECTIVE

Muscle strength is usually measured using isometric hand-held dynamometers (HHDs) in the clinic. However, during functional activities, the muscle acts more dynamically. The aim of this study was to investigate the relation between clinically measured plantar flexor (PF) muscle strength (PFMS) and laboratory measurements of peak ankle plantar flexion power generation (APFPG), peak ankle moment (PAM), peak plantar flexion velocity (PFV) and mean gait velocity in healthy participants.

METHODS

The maximum PFMS on non-dominant sides in 18 able-bodied persons 23.88 (SD 3.55 years) was measured before (Pre-S) and after a stretching (Post-S) procedure (135 sec. × 13 rep. with 5 sec. rest) by using a HHD. The stretching procedure was used to generate temporary PF muscle weakness. Gait analysis was carried out for Pre-S and Post-S conditions. Normalized (by weight and height) and non-normalized HHD scores and differences for both conditions were correlated by Pearson correlation coefficient calculations (p< 0.05).

RESULTS

Reduced PFMS (%23, p< 0.001) in Post-S, according to the HHD scores, has only a weak correlation with APFPG (r> 0.3, p< 0.5). Gait velocity was found to be strongly correlated with APFPG only in the Post-S condition (r= 0.68, p< 0.002). HHD scores and PAM were moderately correlated with the non-normalized Post-S condition (r= 0.44, p= 0.70) and strongly correlated with the non-normalized Pre-S condition (r= 0.62, p< 0.01).

DISCUSSION

HHD scores of plantar flexor muscles give very limited information about the PF performance during walking in healthy individuals. Simple normalization did not improve the relations. Clinically measured isometric muscle strength and muscle weakness have only moderate strengths for establishing a treatment protocol and for predicting performance during walking in neurologically intact individuals.

Dynamic stretching alone can impair slower velocity isokinetic performance of young male handball players for at least 24 hours

There are many adult studies reporting static stretch (SS)-induced deficits and dynamic stretch (DS) performance improvements shortly after the intervention. However, there is only a single study examining stretch-induced performance changes with youth at 24 hours' post-stretch. The objective of this study was to examine physiological responses of young trained athletes at 24-hours after experiencing SS or DS protocols. Eight young male, elite handball players (age: 16.1±5.1 years) were tested prior to-, 3-minutes and 24-hours following the three conditions (DS, SS, Control) in a randomized and counterbalanced order. Similar volumes of SS (2 repetitions of 75s for each leg) and DS (5 repetitions of 30s for each leg) involved one stretch each for the quadriceps and hamstrings. Tests included (i) two 4s maximal voluntary isometric contractions (MVC) at 60° of knee flexion with 2-min rest, (ii) two maximal isokinetic contractions each at 60°/sec and 300°/sec with 1-min rest, and (iii) two drop jumps with 30-sec rest. To simulate a full warm-up, dynamic activity including 5 minutes of aerobic cycling (70 rpm; 1 kilopond), 4 submaximal isometric contractions and 4 drop jumps were instituted before the pre-tests and following the interventions. Two-way repeated measures ANOVAs revealed that 1) both the SS and control conditions exhibited knee extensor 60°.s-1 (SS:-10.3%; p = 0.04, Control: -8.7%; p = 0.07) and 300°.s-1 (SS: -12.9%; p = 0.005, Control: -16.3%; p = 0.02) isokinetic deficits at post-test, 2) DS impaired knee flexor 60°.s-1 isokinetic work and power-related measures at post-test (Work: -10.1%; p = 0.0006; Power: -19.1%; p = 0.08) and at 24-hours' post-test (Work: 9.9%; p = 0.023; Power: -9.6%; p = 0.01), 3) DS (12.07% and 10.47%) and SS (13.7% and 14.6%) enhanced knee flexor 300°.s-1 isokinetic force and power-related measures compared to control. In conclusion, testing-induced knee extensor isokinetic impairments were counterbalanced by DS, however the hip flexion DS could have produced minor muscle damage for at least 24-hours decreasing knee flexor forces and power at 60°.s-1.

Acute muscle stretching and the ability to maintain posture in females with adolescent idiopathic scoliosis

BACKGROUND

Physiotherapy scoliosis specific exercises include exercises to attain and maintain proper posture, as well as flexibility movements such as stretching.

OBJECTIVE

To examine the effect of prior muscle stretching on the performance of posture exercise in females with adolescent idiopathic scoliosis (AIS).

METHODS

Eighteen females with AIS were randomly assigned to perform a posture maintenance task for three minutes preceded by either stretching protocol (group A) or no-stretching (group B). A second session was carried out after three days, where the same procedure was repeated in a reverse order between groups. During each session, three outcomes were tested: the ability to complete the task, the ability to maintain postural body alignment, and the perceived effort.

RESULTS

All participants completed the task in both sessions. Subjects' ability to preserve the required lower trunk alignment decreased following stretching compared to no-stretching. Lower-trunk angle changed toward flexion by 10∘ and 4.3∘ respectively, p= 0.032. There was no difference in perceived effort.

CONCLUSIONS

Prior muscle stretching has a negative effect on the ability to preserve body positional alignment during posture exercise. The present findings should be considered by practitioners when designing protocols for scoliosis-specific exercises. Stretching immediately prior to posture maintenance exercises should be avoided.

Effectiveness of static stretching positioning on post-stroke upper-limb spasticity and mobility: Systematic review with meta-analysis

OBJECTIVE

To systematically review the effects of static stretching with positioning orthoses or simple positioning combined or not with other therapies on upper-limb spasticity and mobility in adults after stroke.

METHODS

This meta-analysis was conducted according to PRISMA guidelines and registered at PROSPERO. MEDLINE (Pubmed), Embase, Cochrane CENTRAL, Scopus and PEDro databases were searched from inception to January 2018 for articles. Two independent researchers extracted data, assessed the methodological quality and rated the quality of evidence of studies.

RESULTS

Three studies (57 participants) were included in the spasticity meta-analysis and 7 (210 participants) in the mobility meta-analysis. Static stretching with positioning orthoses reduced wrist-flexor spasticity as compared with no therapy (mean difference [MD]=-1.89, 95% confidence interval [CI] -2.44 to -1.34; I² 79%, P<0.001). No data were available concerning the spasticity of other muscles. Static stretching with simple positioning, combined or not with other therapies, was not better than conventional physiotherapy in preventing loss of mobility of shoulder external rotation (MD=3.50, 95% CI -3.45 to 10.45; I² 54.7%, P=0.32), shoulder flexion (MD=-1.20, 95% CI -8.95 to 6.55; I² 0%, P=0.76) or wrist extension (MD=-0.32, 95% CI -6.98 to 5.75; I² 38.5%, P=0.92). No data were available concerning the mobility of other joints.

CONCLUSION

This meta-analysis revealed very low-quality evidence that static stretching with positioning orthoses reduces wrist flexion spasticity after stroke as compared with no therapy. Furthermore, we found low-quality evidence that static stretching by simple positioning is not better than conventional physiotherapy for preventing loss of mobility in the shoulder and wrist. Considering the limited number of studies devoted to this issue in post-stroke survivors, further randomized clinical trials are still needed.

CLINICAL TRIAL REGISTRATION

PROSPERO (CRD42017078784).

Acute Effects of Proprioceptive Neuromuscular Facilitation on Peak Torque and Muscle Imbalance

BACKGROUND

The effects of proprioceptive neuromuscular facilitation (PNF) stretching on muscle imbalance are not fully understood. The aim of this study was to examine the acute effects of PNF stretching on knee extension and flexion peak torque (PT), as well as the conventional and functional hamstrings to quadriceps (H:Q) ratios.

METHODS

Fifteen men (age = 22 ± 1 years; body mass = 76 ± 12 kg; height = 176 ± 7 cm) and fifteen women (age = 22 ± 2 years; body mass = 63 ± 8 kg; height = 161 ± 5 cm) performed concentric quadriceps and hamstrings, and eccentric hamstrings muscle actions at different angular velocities (60, 180, and 300°·s^-1 concentric; 60 and 180°·s^-1 eccentric) before and after a bout of PNF stretching, and a control condition.

RESULTS

Neither PNF or control conditions affected concentric PT or H:Q ratios (p > 0.05), apart from knee extension at 60°·s^-1 in men (p = 0.001). However, there was a reduction in hamstrings eccentric PT in both control and PNF conditions for men and women (p = 0.003).

CONCLUSIONS

PNF stretching of the hamstrings may not adversely affect the H:Q ratios, and consequently not negatively affect injury risk associated with muscular strength imbalances.

Acute Effects of Dynamic Stretching on Muscle Flexibility and Performance: An Analysis of the Current Literature

Stretching has long been used in many physical activities to increase range of motion (ROM) around a joint. Stretching also has other acute effects on the neuromuscular system. For instance, significant reductions in maximal voluntary strength, muscle power or evoked contractile properties have been recorded immediately after a single bout of static stretching, raising interest in other stretching modalities. Thus, the effects of dynamic stretching on subsequent muscular performance have been questioned. This review aimed to investigate performance and physiological alterations following dynamic stretching. There is a substantial amount of evidence pointing out the positive effects on ROM and subsequent performance (force, power, sprint and jump). The larger ROM would be mainly attributable to reduced stiffness of the muscle-tendon unit, while the improved muscular performance to temperature and potentiation-related mechanisms caused by the voluntary contraction associated with dynamic stretching. Therefore, if the goal of a warm-up is to increase joint ROM and to enhance muscle force and/or power, dynamic stretching seems to be a suitable alternative to static stretching. Nevertheless, numerous studies reporting no alteration or even performance impairment have highlighted possible mitigating factors (such as stretch duration, amplitude or velocity). Accordingly, ballistic stretching, a form of dynamic stretching with greater velocities, would be less beneficial than controlled dynamic stretching. Notwithstanding, the literature shows that inconsistent description of stretch procedures has been an important deterrent to reaching a clear consensus. In this review, we highlight the need for future studies reporting homogeneous, clearly described stretching protocols, and propose a clarified stretching terminology and methodology.

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.

The Effect of Static Stretching of Peroneal and Tibialis Anterior Muscles on Reaction Time: A Randomized Controlled Study

OBJECTIVE

The aim of this study was to investigate the acute and chronic effects of static stretching on peroneal and tibialis anterior reaction characteristics.

DESIGN

All 23 participants who volunteered for this study were randomly divided into static (n = 12) and control (n = 11) groups. The subjects in the static stretching group performed stretching exercises for the ankle evertor and dorsiflexor muscles 5 days a week for 6 wks. Peroneal and tibialis anterior muscle reaction characteristics were evaluated at the beginning (2 times for acute effect) and end of this period. Electromyographic activity parameters of the muscles were measured using an ankle inversion tilting platform that simulated a sudden ankle inversion. The following were the four different ankle inversion conditions: (a) ankle-neutral, 15-degree inversion; (b) ankle-neutral, 30-degree inversion; (c) ankle-20-degree plantarflexion, 15-degree inversion; and (d) ankle-20-degree plantarflexion, 30-degree inversion.

RESULTS

Either in terms of acute or chronic effects, no significant differences were found after static stretching exercises for peroneal and tibialis anterior muscle reaction time, reaction duration, and muscle activity evaluated in four positions on the ankle inversion simulation platform (P > 0.05).

CONCLUSIONS

In light of these results, it is possible to state that the short duration of static stretching exercises can still be applied before sports activities.

Acute and chronic effects of foam rolling vs eccentric exercise on ROM and force output of the plantar flexors

Foam rolling and eccentric exercise interventions have been demonstrated to improve range of motion (ROM). However, these two modalities have not been directly compared. Twenty-three academy soccer players (age: 18 ± 1; height: 1.74 ± 0.08 m; body mass: 69.3 ± 7.5 kg) were randomly allocated to either a foam rolling (FR) or eccentric exercise intervention designed to improve dorsiflexion ROM. Participants performed the intervention daily for a duration of four weeks. Measurements of dorsiflexion ROM, isometric plantar flexion torque and drop jump reactive strength index were taken at baseline (pre-intervention) and at three subsequent time-points (30-min post, 24-hours post and 4-weeks post). A significant time x group interaction effect was observed for dorsiflexion (P = 0.036), but not for torque or reactive strength index. For dorsiflexion, there was a significant increase in both acute (30-min; P < 0.001) and chronic (4-week; P < 0.001) ROM for the eccentric group, whilst FR exhibited only an acute improvement (P < 0.001). Eccentric training would appear a more efficacious modality than foam rolling for improving dorsiflexion ROM in elite academy soccer players.

Acute Effects of Stretching on Leg and Vertical Stiffness During Treadmill Running

Pappas, PT, Paradisis, GP, Exell, TA, Smirniotou, AS, Tsolakis, CK, and Arampatzis, A. Acute effects of stretching on leg and vertical stiffness during treadmill running. J Strength Cond Res 31(12): 3417-3424, 2017-The implementation of static (SS) and dynamic (DS) stretching during warm-up routines produces significant changes in biological and functional properties of the human musculoskeletal system. These properties could affect the leg and vertical stiffness characteristics that are considered important factors for the success of athletic activities. The aim of this study was to investigate the influence of SS and DS on selected kinematic variables, and leg and vertical stiffness during treadmill running. Fourteen men (age: 22.58 ± 1.05 years, height: 1.77 ± 0.05 m, body mass: 72.74 ± 10.04 kg) performed 30-second running bouts at 4.44 m·s, under 3 different stretching conditions (SS, DS, and no stretching). The total duration in each stretching condition was 6 minutes, and each of the 4 muscle groups was stretched for 40 seconds. Leg and vertical stiffness values were calculated using the "sine wave" method, with no significant differences in stiffness found between stretching conditions. After DS, vertical ground reaction force increased by 1.7% (p < 0.05), which resulted in significant (p < 0.05) increases in flight time (5.8%), step length (2.2%), and vertical displacement of the center of mass (4.5%) and a decrease in step rate (2.2%). Practical durations of SS and DS stretching did not influence leg or vertical stiffness during treadmill running. However, DS seems to result in a small increase in lower-limb force production which may influence running mechanics.

Acute Effects of the Different Intensity of Static Stretching on Flexibility and Isometric Muscle Force

Kataura, S, Suzuki, S, Matsuo, S, Hatano, G, Iwata, M, Yokoi, K, Tsuchida, W, Banno, Y, and Asai, Y. Acute effects of the different intensity of static stretching on flexibility and isometric muscle force. J Strength Cond Res 31(12): 3403-3410, 2017-In various fields, static stretching is commonly performed to improve flexibility, whereas the acute effects of different stretch intensities are unclear. Therefore, we investigated the acute effects of different stretch intensities on flexibility and muscle force. Eighteen healthy participants (9 men and 9 women) performed 180-second static stretches of the right hamstrings at 80, 100, and 120% of maximum tolerable intensity without stretching pain, in random order. The following outcomes were assessed as markers of lower limb function and flexibility: static passive torque (SPT), range of motion (ROM), passive joint (muscle-tendon) stiffness, passive torque (PT) at onset of pain, and isometric muscle force. Static passive torque was significantly decreased after all stretching intensities (p ≤ 0.05). Compared with before stretching at 100 and 120% intensities, ROM and PT were significantly increased after stretching (p ≤ 0.05), and passive stiffness (p = 0.05) and isometric muscle force (p ≤ 0.05) were significantly decreased. In addition, ROM was significantly greater after stretching at 100 and 120% than at 80%, and passive stiffness was significantly lower after 120% than after 80% (p ≤ 0.05). However, all measurements except SPT were unchanged after 80% intensity. There was a weak positive correlation between the intensities of stretching and the relative change for SPT (p ≤ 0.05), a moderate positive correlation with ROM (p ≤ 0.05), and a moderate positive correlation with passive stiffness (p ≤ 0.05). These results indicate that static stretching at greater intensity is more effective for increasing ROM and decreasing passive muscle-tendon stiffness.

The effects of different durations of static stretching within a comprehensive warm-up on voluntary and evoked contractile properties

Evidence for performance decrements following prolonged static stretching (SS) has led to a paradigm shift in stretching routines within a warm-up. Rather than SS, dynamic stretching (DS) and dynamic activity (DA) have replaced SS within warm-up routines. The objective of the present study was to compare the effect of differing lower limb SS durations (30 [SS30s], 60 [SS60s] or 120 s [SS120s] of SS per muscle group or no-stretch control) within a comprehensive warm-up protocol consisting of aerobic activity, DS and DA. Sixteen male participants completed the four stretching conditions in a randomized order, after a 5-min low-intensity (cycle) warm-up and before a DS/DA component on separate days. Tests included passive hip and knee ranges of motion (ROM), maximum voluntary knee extensor/flexor force, force produced at 100 ms (F100), vertical jump height and evoked knee extensor contractile properties. For hip flexion (hamstrings) ROM, SS120s provided the largest increase (5.6-11.7%) followed by SS60s (4.3-11.4%), control (4.4-10.6%) and SS30s (3.6-11.1%). For knee flexion (quadriceps) ROM, SS30s provided the largest increase (9.3-18.2%) followed by SS120s (6.5-16.3%), SS60s (7.2-15.2%) and control (6.3-15.2%). There were decreases in quadriceps F100 following SS in SS120s (29.6%) only. There were increases in vertical jump performance in the control (6.2%), SS60s (4.6%) and SS30s (3.3%). While 120 s SS per muscle increased ROM, even within a comprehensive warm-up routine, it also elicited notable performance decrements. However, moderate durations of SS were observed to improve ROM whilst either having negligible or beneficial (but not detrimental) effects on specific aspects of athletic performance.

The effects of different passive static stretching intensities on recovery from unaccustomed eccentric exercise - a randomized controlled trial

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into 3 groups: high-intensity (70%-80% maximum perceived stretch), low-intensity (30%-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60 s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (creatine kinase and C-reactive protein) were measured before (baseline) and after (24, 48, and 72 h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72 h postexercise. Statistical time × condition interactions observed only for eccentric peak torque (p = 0.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72 h and 0-72 h) and eccentric peak torque (baseline-24 h and baseline-72 h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24 h and 0-72 h), eccentric peak torque (baseline-48 h and baseline-72 h), and isometric peak torque (baseline-72 h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48 h), but likely had harmful effects on eccentric peak torque (baseline-24 h) and creatine kinase (baseline-48 h and baseline-72 h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

Effectiveness of a 16-Week High-Intensity Cardioresistance Training Program in Adults

Greenlee, TA, Greene, DR, Ward, NJ, Reeser, GE, Allen, CM, Baumgartner, NW, Cohen, NJ, Kramer, AF, Hillman, CH, and Barbey, AK. Effectiveness of a 16-week high-intensity cardioresistance training program in adults. J Strength Cond Res 31(9): 2528–2541, 2017—The purpose of this study was to determine the efficacy of a novel, 16-week high-intensity cardioresistance training (HICRT) program on measures of aerobic fitness, agility, aerobic power, muscular endurance, lower-body explosive power, and self-reported activity level. The intervention group (N = 129; 63 f, 24.65 ± 5.55 years) had a baseline V̇o₂max of 39.83 ± 9.13. These individuals participated in 26, 70-minute exercise sessions, and 4 fitness testing sessions. Participants were matched with a nonexercise control group, paired by sex, age, and baseline V̇o₂max. Matched controls (N = 129, 63 f, 24.26 ± 5.59 years) had a baseline V̇o₂max of 39.86 ± 8.59 and completed preintervention and postintervention V̇o₂max testing only. The results demonstrate that participants in the fitness intervention group significantly increased their V̇o₂max (2.72 ± 0.31, M_diff ± SE; p < 0.001) and reported being more physically active (0.42 ± 0.11, M_diff ± SE; p < 0.001) after the intervention. The matched control group showed no significant pre–post intervention changes. Participants in the fitness intervention showed a significant improvement in 3 of 5 components of the fitness field tests. Specifically, significant improvements were observed for the 1-minute rower (5.32 ± 0.505, M_diff ± SE; p < 0.001), 1-minute push-up (8.168 ± 0.709, M_diff ± SE; p < 0.001), and 1.5-mile run tests (1.79 ± 0.169, M_diff ± SE; p < 0.001). No significant improvements were observed for the shuttle run (p = 0.173) or standing long jump (p = 0.137). These findings demonstrate the efficacy of a novel, HICRT intervention across multiple dimensions of fitness for young- and middle-aged adults. High-intensity cardioresistance training affords flexibility for tailoring to meet desired health and fitness outcomes and makes perceivably daunting high-intensity functional training and multimodal sports training more accessible to general, traditionally nonathletic, populations.

Acute effects of different dynamic exercises on hamstring strain risk factors

The purpose of the study was to examine the acute effects of different dynamic exercise interventions on hamstring muscle performance. Thirty-six young men with poor hamstring flexibility were randomly assigned to three intervention groups: jogging combined with dynamic open kinetic chain stretching (DS), jogging combined with dynamic closed kinetic chain stretching (lunge with eccentric hamstring windmills, LEC), and jogging only (CON) groups. Hamstring flexibility, muscle stiffness (area under the curve, AUC), joint position sense (JPS), maximal eccentric strength (ECC), and angle of peak torque (APT) were recorded before and immediately after the exercise interventions. The results showed that the hamstring flexibility increased in DS (p < 0.001); muscle stiffness decreased in DS and was lower than jogging (p < 0.001). Moreover, ECC increased in LEC and was higher than jogging and DS (p < 0.001). APT was different among 3 groups (p < 0.001). Decreased accuracy of JPS was found in DS and jogging (p < 0.001). In conclusion, the dynamic closed kinetic chain stretching (LEC) as compared to open kinetic chain stretching (DS) or jogging group, may be an effective technique to enhance muscle performance during the pre-competition warm-up routine.

The acute effects of stretching with vibration on dynamic flexibility in young female gymnasts

BACKGROUND

While stretching with vibration has been shown to improve static flexibility; the effect of stretching with vibration on dynamic flexibility is not well known. The purpose of this study was to examine the effectiveness of stretching with vibration on acute dynamic flexibility and jump height in novice and advanced competitive female gymnasts during a split jump.

METHODS

Female gymnast (N.=27, age: 11.5±1.7 years, Junior Olympic levels 5-10) participated in this cross-over study. Dynamic flexibility during gymnastic split jumps were video recorded and analyzed with Dartfish software. All participants completed both randomized stretching protocols with either the vibration platform turned on (VIB) (frequency of 30 Hz and 2 mm amplitude) or off (NoVIB) separated by 48 h. Participants performed 4 sets of three stretches on the vibration platform. Each stretch was held for 30 seconds with 5 seconds rest for a total of 7 minutes of stretch.

RESULTS

Split jump flexibility decreased significantly from pre to post measurement in both VIB (-5.8±5.9°) (P<0.001) and NoVIB (-2.6±6.1°) (P=0.041) conditions (adjusted for gymnast level). This effect was greatest in lower skill level gymnasts (P=0.003), while the highest skill level gymnasts showed no significant decrease in the split jump (P=0.105). Jump height was not significantly different between conditions (P=0.892) or within groups (P=0.880).

CONCLUSIONS

An acute session of static stretching with or without vibration immediately before performance does not alter jump height. Stretching with vibration immediately prior to gymnastics competition decreases split jump flexibility in lower level gymnasts more than upper level gymnasts.

Changes in H-reflex amplitude to muscle stretch and lengthening in humans

Spinal reflex excitability is traditionally assessed to investigate neural adjustments that occur during human movement. Different experimental procedures are known to condition spinal reflex excitability. Among these, lengthening movements and static stretching the human triceps have been investigated over the last 50 years. The purpose of this review is to shed light on several apparent incongruities in terms of magnitude and duration of the reported results. In the present review dissimilarities in neuro-spinal changes are examined in relation to the methodologies applied to condition and measure them. Literature that investigated three different conditioning procedures was reviewed: passive dorsiflexion, active dorsiflexion through antagonists shortening and eccentric plantar-flexors contractions. Measurements were obtained before, during and after lengthening or stretching. Stimulation intensities and time delays between conditioning procedures and stimuli varied considerably. H-reflex decreases immediately as static stretching is applied and in proportion to the stretch degree. During dorsiflexions the inhibition is stronger with greater dorsiflexion angular velocity and at lower nerve stimulation intensities, while it is weaker if any concomitant muscle contraction is performed. Within 2 s after a single passive dorsiflexion movement, H-reflex is strongly inhibited, and this effect disappears within 15 s. Dorsiflexions repeated over 1 h and prolonged static stretching training induce long-lasting inhibition. This review highlights that the apparent disagreement between studies is ascribable to small methodological differences. Lengthening movements and stretching can strongly influence spinal neural pathways. Results interpretation, however, needs careful consideration of the methodology applied.

The Efficacy of Dynamic Contract-Relax Stretching on Delayed-Onset Muscle Soreness Among Healthy Individuals: A Randomized Clinical Trial

OBJECTIVE

To evaluate the efficacy of dynamic contract-relax stretching on delayed-onset muscle soreness (DOMS) in the calf muscle of healthy individuals.

DESIGN

Randomized clinical trial.

SETTING

Research laboratory.

PARTICIPANTS

Three groups of 16 healthy participants (n = 48) were recruited by convenience sampling.

INTERVENTIONS

Three sets of resisted bilateral heel-raising exercises until exhaustion were conducted to initiate DOMS. Participants were randomly allocated into control group without any interventions, dynamic contract-relax stretching (DS), or static stretching (SS) groups. Dynamic contract-relax stretching and SS groups performed DS and SS, respectively, on the dominant leg twice a day for 5 consecutive days (before time points of outcome measurements at 24, 48, 72, 96, and 120 hours postexercise, respectively).

MAIN OUTCOME MEASURES

Muscle soreness, lower leg girth, pressure pain threshold (PPT), range of motion (ROM), and muscle strength were measured before exercise, immediately after, and at 24, 48, 72, 96, and 120 hours postexercise.

RESULTS

There was a significant effect of time in all outcome measures including muscle soreness, lower leg girth, PPT, ROM, and muscle strength; however, there were no significant group differences or group by time interactions.

CONCLUSIONS

The effect of DS on relieving DOMS in the calf muscle is insignificant in this study. Further evidence is needed to prove the efficacy of DS on DOMS.

CLINICAL RELEVANCE

Stretching is commonly recommended before and after exercise; however, this study showed no significant impact of DS or SS in treating DOMS.

Acute changes of hip joint range of motion using selected clinical stretching procedures: A randomized crossover study

BACKGROUND

Hip adductor flexibility and strength is an important component of athletic performance and many activities of daily living. Little research has been done on the acute effects of a single session of stretching on hip abduction range of motion (ROM).

OBJECTIVES

The aim of this study was to compare 3 clinical stretching procedures against passive static stretching and control on ROM and peak isometric maximal voluntary contraction (MVC).

DESIGN

Using a randomized crossover study design, a total of 40 participants (20 male and 20 female) who had reduced hip adductor muscle length attended a familiarization session and 5 testing sessions on non-consecutive days.

METHOD

Following the warm-up and pre-intervention measures of ROM and MVC, participants were randomly assigned 1 of 3 clinical stretching procedures (modified lunge, multidirectional, and joint mobilization) or a static stretch or control condition. Post-intervention measures of ROM and MVC were taken immediately following completion of the assigned condition.

RESULTS

An ANOVA using a repeated measure design with the change score was conducted. All interventions resulted in small but statistically significant (p < 0.05) increases (1.0°-1.7°) in ROM with no inter-condition differences except one. Multidirectional stretching was greater than control (p = 0.031).

CONCLUSIONS

These data suggest that a single session of stretching has only a minimal effect on acute changes of hip abduction ROM. Although hip abduction is a frontal plane motion, to effectively increase the extensibility of the structures that limit abduction, integrating multi-planar stretches may be indicated.

Caffeine, acute static stretching and maximum knee flexion strength

BACKGROUND

Reductions in one-repetition maximum lifts (1RM) following static stretching can be attributed to enhanced neural inhibition, which can be reduced by using stimulants like caffeine. This study compared knee-flexion 1RM following either static stretching (SS) or no-stretching (NS), as well as after ingesting either caffeine (C) or placebo (P).

METHODS

Twenty-four participants (12 female, 12 male) performed four random counterbalanced knee flexion 1RM tests. A 1RM test was performed for each condition at the same time of day with ~48 hours separating each test. Static stretching consisted of 5 exercises with the 1RM being performed immediately following the stretching. Caffeine dose was 6 mg/kg body weight, and the placebo was methylcellulose (520 mg). Both doses were administered as pills 60 minutes before the SS or NS procedures.

RESULTS

Two-way repeated measures ANOVA showed a significant main effect for NS vs. SS (P<0.001, ηG2=0.23). The main effect for C vs. P, and the interaction between C vs. P and NS vs. SS were not statistically different. Average 1RMs were: CNS = 512±242 N, CSS = 474±241 N, PNS = 498±247 N, and PSS = 460±247 N.

CONCLUSIONS

It is concluded that static stretching induced strength decrements are not removed by using stimulants at doses allowed by sport governing organizations.

Manipulation of sensory input can improve stretching outcomes

The primary purpose of our study was to assess the influence of modulating sensory input with either transcutaneous electrical nerve stimulation (TENS) or self-massage with therapy balls on the maximal range of motion (ROM) about the ankle joint when stretching the calf muscles. We also investigated the influence of these two conditions on the force capacity and force control of plantar flexor muscles. Twenty healthy adults (25 ± 3 yr) performed three sessions of ankle plantar flexor stretching (three stretches of 30 s each): stretching alone (SS), stretching with concurrent TENS (TENS), and stretching after self-massage using therapy balls (SM). TENS was applied for 60 s prior to and during each stretch, and SM was performed for 60 s prior to each of the three stretches. Maximal voluntary contraction (MVC) torque and force steadiness at 20% MVC were recorded before and at 15 min after the final stretch. Ankle dorsiflexion ROM was assessed before, after, and at 5, 10, and 15 min after the last stretch. The increase in ROM was greater after SM (24%) than after SS (13%) and TENS (9%; p < .001). Maximal discomfort level (0-10 VAS) during stretching was similar for all conditions. MVC torque increased after SM only (p < .001, Cohen's D = 1.5): SM, 16%; SS, -1%; TENS, -3%. Force steadiness did not change. The sensory fibres that contribute to stretch tolerance were engaged by self-massage but not by TENS, resulting in greater increases in flexibility and MVC torque after self-massage.

Acute Passive Static Stretching and Cramp Threshold Frequency

CONTEXT

  Exercise-associated muscle cramps are a common clinical problem for athletes.

OBJECTIVE

  To determine whether acute passive static stretching altered cramp threshold frequency (CTF) of electrically induced muscle cramps.

DESIGN

  Crossover study.

SETTING

  Laboratory.

PATIENTS OR OTHER PARTICIPANTS

  Seventeen healthy college-aged individuals.

INTERVENTION(S)

  Stretching or no stretching.

MAIN OUTCOME MEASURE(S)

  The independent variable was the static stretch versus the no-stretch condition, and the dependent variable was the CTF.

RESULTS

  The CTF increased in both the control (pretest: 18.12 ± 6.46 Hz, posttest: 19.65 ± 7.25 Hz; P = .033) and stretching (pretest: 18.94 ± 5.96 Hz, posttest: 20.47 ± 7.12 Hz; P = .049) groups. No difference between the groups was found (t₁₅ = 0.035, P = .97).

CONCLUSIONS

  Acute passive static stretching did not seem to increase the CTF.

One minute static stretch of plantar flexors transiently increases H reflex excitability and exerts no effect on corticospinal pathways

NEW FINDINGS

What is the central question of this study? What mediates neural responses following static stretching, and how long do these influences last? What is the main finding and its importance? This study shows that 1 min of static stretching inhibits the tendon tap reflex and facilitates the H reflex without influencing motor-evoked potentials. The results indicate that at least two different mechanisms mediate neural responses after static stretching. The purpose of this study was to determine whether the neural responses observed after static stretching are mediated by sensitivity of muscle spindles, spinal excitability or cortical excitability and how long these influences last. Nineteen volunteers (25.7 ± 5.6 years old) were tested for the tendon tap reflex (T-reflex), H reflex and motor-evoked potentials on ankle flexors and extensors immediately, 5 and 10 min after 1 min static stretching applied at individual maximal ankle dorsiflexion, as well as immediately, 5 and 10 min after a control period of the same duration. Comparison of measurements collected immediately after stretching or control conditions revealed that the T-reflex was weaker after stretching than after control (-59.2% P = 0.000). The T-reflex showed a slow recovery rate within the first 150 s after stretching, but 5 min after the inhibition had disappeared. The H reflex increased immediately after stretching (+18.3%, P = 0.036), showed a quick tendency to recover and returned to control values within 5 min from stretching. Motor-evoked potentials were not affected by the procedure. These results suggest that 1 min of static stretching primarily decreases muscle spindle sensitivity and facilitates the H reflex, whereas effects on the motor cortex can be excluded.

Complementing Warm-up with Stretching Routines: Effects in Sprint Performance

The present study aimed to examine the effects of using static or dynamic stretching added to the common warm-up routine for short sprint distances and to repeated sprint performance. In 3 different sessions, 16 college-age men (n=10) and women (n=6) performed one of 3 warm-ups followed by a 2×60 m dash sprint time trial (5 min of rest) in a counterbalanced design. The control warm-up consisted of 10 min of light-intensity running, and the 2 experimental warm-ups included a static or dynamic stretching routine (5 exercises) in the control warm-up. Performance (time) and physiological variables (tympanic temperature, heart rate) were monitored. In the first 60 m time trial, there were no differences between the 3 warm-ups tested ( F =0.21, p=0.73; η _p² =0.01), as opposed to that observed in the second ( F =7.04, p<0.01; η _p² =0.32). The participants were 1.7% faster after the static stretching warm-up compared with the control warm-up. The sum of the time performed in the 2 sprints emphasizes these results, with better performances after the static stretching warm-up than the control (1%) or dynamic stretching warm-up (0.7%). These results suggest that including a set of static or dynamic stretching exercises may enhance sprinting performance. The better performance in the second trial after the warm-up including static stretching suggests that this type of stretching may positively influence repeated sprint performance (<10 s sprint).

Influence of chronic stretching on muscle performance: Systematic review

The aim of the current study was to investigate the influence of chronic stretching on muscle performance (MP) by a systematic review. The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, LILACS, and manual search from inception to June 2016. Randomized and controlled clinical trials, non-randomized, and single group studies that have analyzed the influence of flexibility training (FT) (using any stretching technique) on MP were included. Differently, studies with special populations (children, elderly, and people with any dysfunction/disease), and articles that have used FT protocols shorter than three weeks or 12 sessions were excluded. The MP assessment could have been performed by functional tests (e.g. jump, sprint, stretch-shortening cycle tasks), isometric contractions, and/or isotonic contractions. Twenty-eight studies were included out of 513. Seven studies evaluated MP by stretch-shortening cycle tasks, Ten studies evaluated MP by isometric contractions, and 13 studies assessed MP by isotonic contractions. We were unable to perform a meta-analysis due to the high heterogeneity among the included studies. In an individual study level analysis, we identified that 14 studies found positive effects of chronic stretching on MP. The improvements were observed only in functional tests and isotonic contractions, isometric contractions were not affected by FT. Therefore, FT might have an influence on dynamic MP. However, more studies are necessary to confirm whether FT can positively affect MP.

The acute benefits and risks of passive stretching to the point of pain

PURPOSE

This study evaluated the acute effects of two different stretch intensities on muscle damage and extensibility.

METHODS

Twenty-two physically active women (age 20 ± 1.0 years) were divided into two matched groups and undertook eight sets of 30-s passive hamstring stretching. One group stretched to the point of discomfort (POD) and the other to the point of pain (POP). Hamstring passive torque, sit and reach (S&R), straight leg raise (SLR), and markers of muscle damage were measured before, immediately after stretching and 24 h later.

RESULTS

S&R acutely increased and was still increased at 24 h with median (interquartile range) of 2.0 cm (0.5-3.75 cm) and 2.0 cm (0.25-3.0 cm) for POP and POD (p < 0.05), respectively, with no difference between groups; similar changes were seen with SLR. Passive stiffness fully recovered by 24 h and there was no torque deficit. A small, but significant increase in muscle tenderness occurred at 24 h in both groups and there was a very small increase in thigh circumference in both groups which persisted at 24 h in POP. Plasma CK activity was not raised at 24 h.

CONCLUSION

Stretching to the point of pain had no acute advantages over stretching to the discomfort point. Both forms of stretching resulted in very mild muscle tenderness but with no evidence of muscle damage. The increased ROM was not associated with changes in passive stiffness of the muscle but most likely resulted from increased tolerance of the discomfort.

Acute effect of stretching modalities on global coordination and kicking accuracy in 12-13year-old soccer players

The aim of the study was to compare the effect of stretching procedures on global coordination and accuracy in instep soccer kicks achieved in different stress conditions. Twenty male young soccer players completed the global coordination test (GC), the instep kicking accuracy test in free (FKA) and in time-pressure (TPKA) conditions, either after static (SS), dynamic (DS), ballistic (BS) or no-stretching (CTR) protocols, on nonconsecutive days and in a randomized order. After performing a 5min standardized intensity jogging (70% of MAV), followed by stretching exercises for 10min, each participant completed, successively, the GC, FKA and TPKA tests. Accuracy data, heart-rate, rating of perceived exertion and task difficulty perception were recorded and analyzed using a two-way ANOVA. GC scores were analyzed using one way ANOVA with repeated measures. The results showed higher GC and TPKA performances after DS and BS procedures. However, there was no effect of the stretching procedures on FKA. The GC scores increased by 10.8% and 7.2% after DS and BS, respectively, but were not affected by SS. Compared to FKA, the TPKA accuracy significantly decreased by 20.2% after CTR (p<0.01) and 30.7% SS (p<0.001) with no significant difference after DS (10.1%; p>0.05) and BS (11.0%; p>0.05). The use of dynamic and ballistic stretching yielded to better GC scores and helped reducing the adverse effect of time-pressure on instep kicking accuracy. Consequently, dynamic and ballistic exercises can be recommended before practicing activities requiring coordination and lower limbs speed and accuracy.

EFEITO AGUDO DO VOLUME DE ALONGAMENTO ESTÁTICO NO DESEMPENHO NEUROMUSCULAR DE JOVENS E IDOSAS

RESUMO Introdução: Os exercícios prévios de alongamento estático (AE) podem promover decréscimo transitório da força muscular. Características dos protocolos de AE e da amostra estudada podem interferir no desempenho neuromuscular subsequente às rotinas de alongamento. Objetivo: Investigar o efeito agudo de dois diferentes volumes de AE sobre o sistema neuromuscular de mulheres jovens e idosas durante a execução do leg press horizontal. Métodos: Vinte e quatro mulheres (12 jovens e 12 idosas), aparentemente saudáveis, compareceram ao local de realização do experimento em seis ocasiões distintas. Nas três primeiras visitas realizaram-se coleta dos dados pessoais, de dados antropométricos, familiarização com o protocolo de AE e registro de esforço isométrico no leg press horizontal. Nas três últimas visitas, foram realizados registros da curva força-tempo isométrica e atividade eletromiográfica (EMG) dos músculos vasto medial e vasto lateral após realização de uma de três condições experimentais: controle (sem alongamento), alongamento com volume total de 60 segundos e 120 segundos. A ordem das condições experimentais foi aleatorizada. O protocolo de AE envolveu três exercícios executados em duas séries de 30 segundos (AE60) ou em quatro séries de 30 segundos (AE120). O teste ANOVA two-way foi utilizado para análises dos dados. Resultados: Nenhuma das rotinas de AE acarretou alteração de taxa de desenvolvimento de força (TDF), contração voluntária máxima e atividade EMG nas mulheres jovens e idosas. Conclusões: Diferentes volumes de AE, em conformidade com recomendações atuais, não influenciaram o desempenho neuromuscular de mulheres jovens e idosas no exercício leg press horizontal.

The effects of a combined static-dynamic stretching protocol on athletic performance in elite Gaelic footballers: A randomised controlled crossover trial

OBJECTIVES

To determine the effect of three different static-dynamic stretching protocols on sprint and jump performance in Gaelic footballers.

DESIGN

Double-blind, controlled, crossover trial.

SETTING

Sports Institute research environment.

PARTICIPANTS

Seventeen male elite level Gaelic footballers, aged 18-30 years, completed three stretching protocols.

MAIN OUTCOME MEASURES

Athletic performance was measured by countermovement jump height and power, and timed 10 m, 20 m, and 40 m sprints.

RESULTS

Static stretching reduced sprint speed by 1.1% over 40 m and 1.0% over 20 m. Static stretching also reduced countermovement jump height by 10.6% and jump power by 6.4%. When static stretching was followed by dynamic stretching, sprint speed improved by 1.0% over 20 m and 0.7% over 40 m (p < 0.05). The static - dynamic stretching protocol also improved countermovement jump height by 8.7% (p < 0.01) and power by 6.7% (p < 0.01).

CONCLUSIONS

Static stretching reduces sprint speed and jump performance. Static stretching should be followed by dynamic stretching during warm-up to nullify any performance deficits caused by static stretching.

Endoscopist fatigue estimates and colonoscopic adenoma detection in a large community-based setting

BACKGROUND AND AIMS

Endoscopist fatigue may impact colonoscopy quality, but prior studies conflict, and minimal data exist from community-based practices where most colonoscopies are performed.

METHODS

Within a large, community-based integrated healthcare system, we evaluated the associations among 4 measures of endoscopist fatigue and colonoscopic adenoma detection from 2010 to 2013. Fatigue measures included afternoon versus morning colonoscopy and the number of GI procedures performed before a given colonoscopy, including consideration of prior procedure complexity. Analyses were adjusted for potential confounders using multivariate logistic regression.

RESULTS

We identified 126 gastroenterologists who performed 259,064 total GI procedures (median, 6 per day; range, 1-24), including 76,445 screening and surveillance colonoscopies. Compared with morning examinations, colonoscopies in the afternoon were not associated with lower adenoma detection for screening examinations, surveillance examinations, or their combination (OR for combination, .99; 95% CI, .96-1.03). The number of procedures performed before a given colonoscopy, with or without consideration of prior procedure complexity, was also not inversely associated with adenoma detection (OR for adenoma detection for colonoscopies in the fourth quartile of fatigue based on the number of prior procedures performed vs colonoscopies performed as the first procedure of the day, .99; 95% CI, .94-1.04).

CONCLUSIONS

In a large community-based setting, adenoma detection for screening and surveillance colonoscopies were not associated with either time of day or the number of prior procedures performed by the endoscopist, within the range of procedure volumes evaluated. The lack of association persisted after accounting for prior procedure complexity.

The Acute Effects of Static Stretching on Speed and Agility Performance Depend on Stretch Duration and Conditioning Level

Avloniti, A, Chatzinikolaou, A, Fatouros, IG, Avloniti, C, Protopapa, M, Draganidis, D, Stampoulis, T, Leontsini, D, Mavropalias, G, Gounelas, G, and Kambas, A. The acute effects of static stretching on speed and agility performance depend on stretch duration and conditioning level. J Strength Cond Res 30(10): 2767-2773, 2016-Although static stretching (SS) is an integral part of physical preparation before training and competition, its usefulness in regards to power performance improvement has been questioned. The aim of this study was to investigate the effect of 6 SS durations on speed and agility performance. According to a cross-over design, 34 trained men (age, 20.5 ± 1.4 years; height, 1.81 ± 0.2 m; weight, 77.2 ± 2.6 kg; body fat, 8.2 ± 2.6%) participated in a control session (no stretch) and 6 experimental conditions (10, 15, 20, 30, 40, and 60 seconds) performed in a randomized order. Performance in speed (10 and 20 m) and agility (T-test) was measured after the control and experimental conditions. Static stretching, consisting of stretches for hip extensors, hip adductors, knee extensors, knee flexors, and ankle sole flexors, was performed after light cardiovascular exercise (8 minutes). A 1-way repeated-measures analysis of variance showed that speed was improved only by SS of short duration (15/20 seconds), whereas agility remained unaffected by all SS trials. When participants' speed and agility level was taken into account, it was revealed that only those of moderate performance demonstrated an improved speed (in 15- and 20-second trials) and agility (in 10- and 15-second trials) performance. These results suggest that short-duration SS protocols induce an acute improvement of speed and agility performance, whereas longer-duration SS protocols have neither positive nor negative effect. Furthermore, it seems that individuals of lower speed and agility performance level are more likely to benefit by a short-duration SS protocol.

Discrete quasi-linear viscoelastic damping analysis of connective tissues, and the biomechanics of stretching

The time- and frequency-dependent properties of connective tissue define their physiological function, but are notoriously difficult to characterize. Well-established tools such as linear viscoelasticity and the Fung quasi-linear viscoelastic (QLV) model impose forms on responses that can mask true tissue behavior. Here, we applied a more general discrete quasi-linear viscoelastic (DQLV) model to identify the static and dynamic time- and frequency-dependent behavior of rabbit medial collateral ligaments. Unlike the Fung QLV approach, the DQLV approach revealed that energy dissipation is elevated at a loading period of ∼10s. The fitting algorithm was applied to the entire loading history on each specimen, enabling accurate estimation of the material's viscoelastic relaxation spectrum from data gathered from transient rather than only steady states. The application of the DQLV method to cyclically loading regimens has broad applicability for the characterization of biological tissues, and the results suggest a mechanistic basis for the stretching regimens most favored by athletic trainers.

Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance-Trained Women

Lima, CD, Brown, LE, Wong, MA, Leyva, WD, Pinto, RS, Cadore, EL, and Ruas, CV. Acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. J Strength Cond Res 30(11): 3220-3227, 2016-Stretching is used to increase joint range of motion, but the acute effects can decrease muscle strength. However, this may depend on the population or mode of stretching. The purpose of this study was to compare the acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. Fifteen resistance-trained women (age 23.8 ± 1.80 years, mass 67.47 ± 7.77 kg, height 168.30 ± 5.53 cm) and 12 ballet dancers (age 22.8 ± 3.04 years, mass 58.67 ± 5.65 kg, height 168.00 ± 7.69 cm) performed 5 days of testing. The first day was control (no stretching), whereas the other 4 days were static or ballistic stretching in a counterbalanced order. Range of motion, strength, and fatigue tests were also performed. Both groups demonstrated a significant decrease in hamstrings strength after static (102.71 ± 2.67 N·m) and ballistic stretching (99.49 ± 2.61 N·m) compared with control (113.059 ± 3.25 N·m), with no changes in quadriceps strength. For fatigue, only ballet dancers demonstrated a decrease from control (71.79 ± 4.88%) to ballistic (65.65 ± 8.19%), but no difference with static (65.01 ± 12.29%). These findings suggest that stretching decreases hamstrings strength similarly in ballet dancers and resistance-trained women, with no differences between modes of stretching. However, ballistic stretching only decreased muscular fatigue in ballet dancers, but not in resistance-trained women. Therefore, no stretching should be performed before strength performance. However, ballistic stretching may decrease acute muscular fatigue in ballet dancers.

Changes in joint range of motion and muscle-tendon unit stiffness after varying amounts of dynamic stretching

The purpose of this study was to examine the effects of varying amounts of dynamic stretching (DS) on joint range of motion (ROM) and stiffness of the muscle-tendon unit (MTU). Fifteen healthy participants participated in four randomly ordered experimental trials, which involved one (DS1), four (DS4) and seven (DS7) sets of DS, or control conditions/seated at rest (CON). Each DS set consisted of 15 repetitions of an ankle dorsiflexion-plantarflexion movement. The displacement of the muscle-tendon junction (MTJ) was measured using ultrasonography while the ankle was passively dorsiflexed at 0.0174 rad · s^‒1 to its maximal dorsiflexion angle. Passive torque was also measured using an isokinetic dynamometer. Ankle ROM was significantly increased after DS4 and DS7 compared with the pre-intervention values (P < 0.05), but there were no significant differences in ankle ROM between DS4 and DS7. No differences were observed in ankle ROM after DS1 and CON. In addition, the stiffness of the MTU, passive torque and displacement of the MTJ at submaximal dorsiflexion angles did not change in any of the experimental conditions. These results indicate that DS4 increased ankle ROM without changing the mechanical properties of the MTU, and that this increase in ankle ROM plateaued after DS4.

The effects of taping, stretching, and joint exercise on hip joint flexibility and range of motion

[Purpose] This study aimed to examine the effects of joint exercise, taping, and stretching on hip joint flexion, flexibility, and range of motion. [Subjects and Methods] Forty-five college students in their 20s were randomly assigned and equally divided into three groups, as follows: a stretching group, a taping and exercise group, and an exercise group. Changes in trunk range of motion and hip joint flexibility of the three groups were measured before and after the intervention. [Results] Comparison between flexibility before and after the intervention revealed statistically significant changes in all three groups. Moreover, the evaluation of joint range of motion after the intervention showed that there were statistically significant changes in all three groups. [Conclusion] Taping, stretching, and joint exercise are considered effective for the increase in flexibility and joint range of motion.