30-s Stretch Research Articles

Stretching, Isometrics, and Aerobic Exercise for Decreasing Blood Pressure Post-Exercise: A Randomized Cross-Over Study.

We compared stretching, isometrics, and aerobic exercise for effectiveness in decreasing blood pressure post-exercise. Using a randomized crossover design, 5 males and 4 females (21.3y; normotensive) participated in four 30-minute sessions on separate days: static stretching (30s stretches, major muscle groups), isometric exercise, aerobic cycling (75% VO2peak), and control (rest), with blood pressure and heart rate measured before exercise (or rest) and for 60 minutes post-exercise (or rest). Aerobic exercise and stretching decreased post-exercise systolic blood pressure (~10 mmHg each) (p<0.05) whereas isometric exercise and the control condition did not significantly decrease post-exercise blood pressure. Stretching is similar to aerobic exercise for reducing blood pressure post-exercise. ClinicalTrials.gov Identifier: NCT06628635.

The acute effect of passively assisted trunk stretching on central arterial stiffness and blood pressure in middle-aged to older adults.

We examined the effects of acute trunk stretching on central arterial stiffness and central and peripheral blood pressure in middle-aged to older adults. Twenty-eight middle-aged to older adults (14M/14F, 72 ± 7years, 28.5 ± 5.3kg/m2) completed this randomized, controlled, crossover design trial. We measured carotid-femoral pulse wave velocity (cf-PWV) and central and peripheral blood pressures (BP) before and after a single bout of passively assisted trunk stretching (i.e., five rounds of six 30-s stretches) and a time-matched seated control visit (i.e., 30-min). Changes (Δ; post - pre) in cf-PWV and central and peripheral BP were compared between visits and sexes using separate linear mixed-effects models controlling for baseline values. Compared with seated control, central (systolic: - 3 ± 7mmHg; diastolic: - 2 ± 5mmHg) and peripheral (systolic: - 2 ± 8mmHg; diastolic: - 1 ± 4mmHg) BP were reduced following acute trunk stretching (ps ≤ 0.001). Between-visit differences for ∆cf-PWV (stretch: 0.09 ± 0.61m/s; control: 0.37 ± 0.68m/s, p = 0.038) were abolished when controlling for change in mean arterial pressure (∆MAP) (p = 0.687). The main effects of sex were detected for changes in systolic BPs (ps ≤ 0.029); more males (n = 13) saw BP reductions than females (n = 7). These findings demonstrate the superiority of acute trunk stretching over passive sitting of equated duration for BP in middle-aged to older adults, with an appreciable effect in males compared to females.

Self-massage prior to stretching improves flexibility in young and middle-aged adults

ABSTRACTWe examined the influence of stretching alone (SS) or combined with self-massage (SM) on maximal ankle dorsiflexion angle, maximal voluntary contraction (MVC) torque and calf muscle activity, and subcutaneous tissue thickness in 15 young (25 ± 3 years) and 15 middle-aged (45 ± 5 years) adults. Participants performed two sessions of calf muscle stretches (3x 30-s stretches, 30-s rest): stretch after a 60-s control condition (SS) and stretch after 60 s of self-massage with therapy balls (SM). Evaluations were performed before and 5 min after the intervention. Linear mixed effects model revealed no main effect for age on ROM or MVC and significant main effects for treatment and time. Change in ankle angle was greater after SM: SS = 3.1 ± 2°, SM = 6.2 ± 3.3° (Hedges’ g = 0.98, p < 0.001). Similar results were observed for MVC torque: SS = −4 ± 16%, SM = 12 ± 16% (Hedges’ g = 0.97, p = 0.0001). Changes in MVC torque and absolute EMG amplitude were correlated, but subcutaneous tissue thickness was not altered by treatment. The gains in ROM were more pronounced in less flexible middle-aged adults, underscoring the need to include flexibility exercises in their training.

Changes in Quadriceps Motoneuron Pool Excitability due to Static Stretch and/or Explosive Contraction

PURPOSE: To observe how static stretch and/or explosive contraction (vertical jump) changes quadriceps motoneuron pool excitability (MNPE). METHODS: Fifteen healthy people (13 males and 2 females) completed four data collection sessions on separate days with a 48-hour interval between sessions. A 4 (condition) × 3 (time) cross-over randomised controlled laboratory study was performed. Conditions were A) stretching and jumping, B) control (no stretching) and jumping, C) stretching and control (no jumping), and D) control (no stretching and jumping). Thomas test was used to stretch both quadriceps (30-s × 3 for each quadriceps). For jumping, two-legged maximal vertical jumps using lower-extremity pre-stretch and double-arm swinging were performed (assessed by Vertec: 3 trials with a-30 s rest interval). To assess quadriceps MNPE, the right side of vastus medialis peak Hoffmann reflexes normalised by peak motor response were recorded at baseline, 0-min post-condition, and 20-min post-condition. For the conditions including the jumping task, jump heights were also recorded after measurements of MNPE at each time point. To test condition effects over time, mixed model analysis of variances were performed and between-time effect sizes (ES) were calculated. RESULTS: Quadriceps MNPE did not change among four conditions at any time point (F6,154=1.71, p=0.12). There was a trend that quadriceps MNPE at 0-min post-condition, as compared to the baseline values, was reduced under the condition A (5%, ES=0.46) and C (8%, ES=0.43), and increased under the condition B (10%, ES=0.66). An increased quadriceps MNPE under the condition B appeared to be maintained until the 20-min post-condition measurement (8%, ES=0.52). Jump heights did not change among two conditions (A and B) at any time point (F2,70=2.14, p=0.13). Jump heights between-time ES were very small (<0.1 for all values). CONCLUSIONS: Our data suggest that (1) static stretch may reduce MNPE, (2) explosive contraction may increase MNPE for 20-min, (3) a combination of static stretch and explosive contraction may decrease MNPE, (4) three sets of 30-s stretch does not acutely affect explosive performance, and (5) changes in MNPE minimally influence explosive performance. This study was funded by Yonsei Institute of Sports Science & Exercise Medicine.

Influence of maximum range of motion and stiffness on the viscoelastic stretch response

We examined the influence of maximum range of motion (MROM) and passive stiffness on the viscoelastic stretch response. Four 30-s constant-angle passive stretches of the plantar flexors at a predetermined torque were performed to determine the rate and relative change in stress relaxation (decline in torque during each 30-s stretch) and creep (increase in ankle joint angle across all 4 stretches). Stress relaxation and creep responses were examined between participants after they were ranked into high and low groups based on MROM and passive stiffness values. Stress relaxation responses were unaffected by MROM and passive stiffness; however, creep was influenced by differences in passive stiffness but not MROM. Passive stiffness but not MROM influences the acute viscoelastic response to passive stretching. Participants with less stiff plantar flexors experience greater increases in range of motion when they are stretched at a constant torque.

The Influence Of A 20-Minute Jog On The Viscoelastic Properties Of The Plantar Flexor Muscles

INTRODUCTION: It is commonly believed that passive stretching is most appropriate when performed following a workout. However, the viscoelastic response during passive stretching prior to and following a common cardiovascular workout is unclear. PURPOSE: To examine the influence of a 20-min, moderate-intensity jog on the viscoelastic properties of the plantar flexor muscles. METHODS: Six recreationally active males (mean age ± SD = 23 ± 3 yrs; stature = 172 ± 4 cm; mass = 75 ± 7 kg) participated in two randomized experimental trials separated by 2-7 days; 1) a 20-min jog (mean % age-predicted HRmax ± SD = 83 ± 4) on a Quinton Club Track treadmill or 2) 20-min rest. Each condition was immediately followed by six 30-s stretches on a calibrated Biodex System 4 dynamometer. The dynamometer slowly (5°·sec-1) stretched the plantar flexors to a constant torque (i.e. 27 Nm) value (point of discomfort). Once this threshold was reached, the dynamometer was stopped and held at the same position for the entire 30-s. During the six 30-s stretches, torque values were recorded every 5-s (0, 5, 10, 15, 20, 25, and 30) to assess viscoelastic stress relaxation and position was recorded at the onset of each stretch to measure viscoelastic creep. Two-way repeated measures analysis of variance (ANOVA) was used to analyze changes in joint angle and a three-way repeated measures ANOVA was used to analyze changes in torque during the six 30-s stretches. An alpha of P≤0.05 was used to determine statistical significance. RESULTS: For stress relaxation, there was a significant interaction for stretch x time (P = 0.001). Torque declined in a similar fashion for all stretches over the 30-s stretch period and began to plateau around 25-s. For creep, there was a significant main effect for stretch (P = 0.001). The joint angle for stretch 6 was greater than stretches 1-4, stretches 3-5 were greater than stretches 1-2, and stretch 2 was greater than stretch 1. CONCLUSIONS: The viscoelastic responses (stress relaxation and creep) were similar for both conditions. These findings suggest that a 20-min, moderate-intensity jog had little influence on the viscoelastic responses seen during a practical stretching protocol.

Dynamics of viscoelastic creep during repeated stretches

The present study examined the viscoelastic creep responses in vivo during repeated constant-torque stretches in human skeletal muscle. Twelve healthy participants completed four consecutive 30-s constant-torque passive stretches of the right plantar flexor muscles. Position and surface electromyographic (EMG) amplitude values were quantified at every 5-s period and the percent change in position was quantified for each 5-s epoch relative to the total increase in ankle joint position for each stretch. In addition, the absolute changes in position were plotted on a logarithmic time scale and fit with a linear regression line to examine both the rate of increase (slope) and the overall increase in position over the entire stretch (y-intercept). The percent change and slope were similar (P>0.05) over all four stretches, with the majority of increases in position occurring within the initial 15-20 s of each stretch (84%). Absolute ankle joint position and the y-intercept increased (P<0.05) following both the first and second stretch but plateaued (P>0.05) after the third stretch. In addition, EMG amplitude values did not change (P>0.05) during or between each 30-s stretch. These data indicate that the amount and rate of viscoelastic creep were similar during practical durations of constant-torque stretching despite no change in ankle joint position following three 30-s stretches.

Viscoelastic creep in the human skeletal muscle–tendon unit

The purposes of the present study were to (1) characterize viscoelastic creep in vivo in the human skeletal muscle-tendon unit and (2) to examine the consistency of these responses during a single 30-s stretch. Twelve volunteers (mean +/- SD = 22 +/- 3 years; height = 169 +/- 11 cm; mass = 70 +/- 17 kg) participated in two separate experimental trials. Each trial consisted of a 30-s constant-torque stretch of the plantar flexor muscles. Position (degrees) values were quantified at every 5-s period (0, 5, 10, 15, 20, 25, and 30 s) and the percent change in position was quantified for each 5-s epoch (0-5, 5-10, 10-15, 15-20, 20-25, and 25-30 s) relative to the total increase in the range of motion. In addition, the intraclass correlation coefficient (ICC) and standard errors of the measurement (SEM) were calculated for test-retest reliability. These results indicated that position increased over the entire 30-s stretch (P < 0.05), while the majority of the increases in position (73-85%) occurred during the first 15-20 s. ICC values were >or = 0.994 and SEM values (expressed as percentage of the mean) were <or= 1.54%. In conclusion, these results demonstrate viscoelastic creep in vivo in the human skeletal muscle-tendon unit and suggest that these responses may be reliable for future studies.

Determining the minimum number of passive stretches necessary to alter musculotendinous stiffness

In this study, we examined the minimum number of constant-torque passive stretches necessary to reduce musculotendinous stiffness. Thirteen healthy individuals (mean age 22 years, s = 3; stature 1.67 m, s = 0.1; mass 66 kg, s = 13 kg) volunteered to participate in the investigation and underwent four 30-s constant-torque passive stretches of the plantar flexor muscles. Musculotendinous stiffness was examined from the angle–torque curves generated prior to the passive stretches, at the beginning of each 30-s stretch, and immediately following the four 30-s passive stretches. The results indicated that musculotendinous stiffness of the plantar flexors was reduced following two 30-s constant-torque passive stretches (P < 0.05) compared with the pre- musculotendinous stiffness assessment. Musculotendinous stiffness remained depressed following the third and fourth stretches, but did not decrease further. These findings suggest that two 30-s bouts of constant-torque passive stretching may be necessary to cause a significant decrease in musculotendinous stiffness of the plantar flexor muscles.

A Single 30-s Stretch Is Sufficient to Inhibit Maximal Voluntary Strength

While it has been well established that an acute stretching program can inhibit maximal muscle performance, the amount of stretching needed to produce the deleterious response is unknown. Therefore this study examined the dose-response relationship between acute stretching and strength inhibition. Eighteen college students performed a one repetition maximum (1-RM) test of knee-flexion following 0, 1, 2, 3, 4, 5, or 6 30-s bouts of hamstring stretching held at the limit of toleration. All seven dose variations were done by each subject, with each variation done on a separate day. One week separated each test, and the order of the stretch variations was balanced across the seven testing days. Stretching significantly (p < .05) reduced 1-RM after one 30-s stretch (5.4%), and continued to decrease 1-RM up to and including six 30-s stretches (12.4%). A single 30-s stretch, if held at the limit of toleration, is sufficient to cause an inhibition in a person's 1-RM. Additional bouts of stretching will further decrease the 1-RM, suggesting that multiple mechanisms may be involved in stretch-induced strength inhibition.

Viscoelastic Creep In Human Skeletal Muscle

INTRODUCTION: Viscoelastic creep can be defined as the increase in tissue length under a constant force or torque. PURPOSE: To examine viscoelastic creep in the plantar flexor muscles. METHODS: Thirteen healthy participants (mean age ± SD = 22 ± 3 yrs; stature = 168 ± 12 cm; mass = 69 ± 17 kg) performed four 30-s constant-torque passive stretches of the plantar flexor muscles on a calibrated Biodex System 3 dynamometer. Each 30-s passive stretch was completed by the dynamometer lever arm by passively dorsiflexing the foot at 5°/s to the point of discomfort, but not pain as acknowledged by the participant. This was quantified as the maximum tolerable passive torque threshold (i.e. 33 N·m), which was held constant for all 4 stretches while the change in dorsiflexion position was monitored under the constant passive torque. Each 30-s passive stretch was separated by 20 s of rest. Position (°) values were sampled from the dynamometer at 1 KHz during the stretches and were quantified at every 5-s period (0, 5, 10, 15, 20, 25, and 30 s). In addition, the percent change in position was quantified for each 5-s epoch (0-5, 5-10, 10-15, 15-20, 20-25, and 25-30 s) relative to the total increase in range of motion (ROM) for each 30-s stretch. A two-way repeated measures ANOVA [stretch × time; 4 × 7] was used to analyze the absolute changes in position, whereas a two-way repeated measures ANOVA [stretch × time; 4 × 6] was used to analyze the percent changes in ROM. RESULTS: For each 30-s stretch, the absolute position increased such that 0 < 5 < 10 < 15 < 20 < 25 < 30 s (P<0.05). At all time points, the position for stretch 1 was less than stretches 2 - 4 (P<0.05), and stretch 2 was less than stretches 3 - 4 (P<0.05). There were no differences at any time points between stretches 3 and 4 (P>0.05). The percent changes in ROM were the same for stretches 1, 2, 3, and 4 during each epoch (P<0.05), however, as the stretch progressed for 30 s, the relative increases in ROM diminished. CONCLUSIONS: During these constant-torque stretches, most of the increases in range of motion occurred as a result of the first two 30-s stretches, since there were no differences in dorsiflexion position between stretches 3 and 4. In addition, the relative changes in ROM that occurred during each of the four 30-s stretches were the same, but the greatest increases (42%) occurred during the first 5-s.

A Single 30-s Stretch Is Sufficient to Inhibit Maximal Voluntary Strength

A Single 30-s Stretch Is Sufficient to Inhibit Maximal Voluntary Strength

Disuse atrophy increases the muscle mechanoreflex in rats

We investigated the effect of disuse atrophy on the magnitude of the muscle mechanoreflex. The left leg of eight rats (6-7 wk, male) was put in a plaster cast for 1 wk. The rats were decerebrated at the midcollicular level. We recorded the pressor and cardioaccelerator responses to 30-s stretch of the calcaneal tendon, which selectively stimulated the muscle mechanosensitive receptors in the left atrophied and right control triceps surae muscles. Atrophied muscles showed significantly lower mass control muscles (1.0 +/- 0.1 vs. 1.4 +/- 0.1 g; P < 0.05). At the same stretch tension (229 +/- 20 g), the pressor response to stretch was significantly greater in the atrophied muscles than in the control muscles (13 +/- 3 vs. 4 +/- 2 mmHg, P < 0.05). The cardioaccelerator response was not significantly different (8 +/- 4 vs. 4 +/- 2 beats/min). Comparing responses at the same relative tension (57 +/- 6 vs. 51 +/- 8% of maximal tension), the pressor response was still significantly greater in the atrophied triceps surae than in the control (14 +/- 4 vs. 4 +/- 2 mmHg; P < 0.05). These results suggest that disuse atrophy increases the magnitude of muscle mechanoreflex.

Acute effects of stretching duration on the range of motion of elderly women

Summary The effect of the duration of static stretching as well as that of multiple stretches in acute stretching protocols has not been extensively examined in the elderly. The aim of the present study was to investigate the acute effects of stretching duration on the range of motion (ROM) of the lower extremities and the trunk in elderly women, when stretching is performed once or in multiple repetitions while controlling the total amount of the time spent in one stretching session. Twenty sedentary subjects aging 65–85 years old (mean age=75.9) participated in this study. Subjects were recruited through advertisements in the local newspapers, as well as by word to mouth. Participants were healthy with no history of musculoskeletal or neurological disease. Subjects performed three static stretching protocols lasting for 60s each, in non-consecutive training sessions. The first stretching protocol comprised of a 60s stretch (1×60), the second of two 30s stretches (2×30), whereas the third was of four 15s stretches (4×15). ROM was determined during hip flexion, extension and abduction, knee flexion, and ankle dorsiflexion for the right and left side of the body, as well as during trunk flexion, using a flexometer and a goniometer. A mixed within—and between—subjects analysis of variance (ANOVA) with repeated measures revealed similar ROM values between both sides of the body, for all measured joints. No significant differences were observed between the stretching protocols. Further statistical analysis indicated significant ( P 0.001 ) improvements after the stretching exercises, in all flexibility protocols. The findings suggest that a single 60-s static stretch of the lower extremities and trunk's muscles produced the same effect as two 30s and four 15s stretches, during a flexibility training session involving sedentary elderly women.

Effects of Static and Hold-Relax Stretching on Hamstring Range of Motion Using the FlexAbility LE1000

The purposes of this study were to determine the effects of static and hold-relax stretching on hamstring range of motion and to examine the reliability of the FlexAbility LE1000 compared with the goniometrically measured active knee-extension test. Forty-two participants (18–25 years old) were assigned to either a control, static, or hold-relax training group. Participants were stretched four times a week over a 6-week period, with four 30-s stretches per session using a straight-leg-raise method on the FlexAbility LE1000. It was determined that both static and hold-relax techniques significantly improved hamstring flexibility (ISLR: +33.08° ± 9.08° and +35.17° ± 10.39°, respectively). Participants of both techniques reached a plateau in flexibility improvement between Weeks 4 and 5. Thus, static and hold-relax stretching are equally effective in improving hamstring ROM. The FlexAbility LE1000 and the goniometer were both found to be highly reliable. Therefore, either measurement technique could be used successfully to measure hip-flexion ROM.