Changes in Flexibility and Force are not Different after Static Versus Dynamic Stretching

Acute and Prolonged Effects of 300 sec of Static, Dynamic, and Combined Stretching on Flexibility and Muscle Force

Static stretching (SS), dynamic stretching (DS), and combined stretching (CS; i.e., DS+SS) are commonly performed as warm-up exercises. However, the stretching method with the greatest effect on flexibility and performance remains unclear. This randomized crossover trial examined acute and prolonged effects of SS, DS, and CS on range of motion (ROM), peak passive torque (PPT), passive stiffness, and isometric and concentric muscle forces. Twenty healthy young men performed 300 sec of active SS, DS, or CS (150-sec SS followed by 150-sec DS and 150-sec DS followed by 150-sec SS) of the right knee flexors on four separate days, in random order. Subsequently, we measured ROM, PPT, and passive stiffness during passive knee extension. We also measured maximum voluntary isometric and concentric knee flexion forces and surface electromyographic activities during force measurements immediately before, immediately after, and 20 and 60 min after stretching. All stretching methods significantly increased ROM and PPT, while significantly decreasing isometric knee flexion force (all p < 0.05). These changes lasted 60 min after all stretching methods; the increases in ROM and PPT and the decreases in isometric muscle force were similar. All stretching methods also significantly decreased passive stiffness immediately after stretching (all p < 0.05). Decreases in passive stiffness tended to be longer after CS than after SS or DS. Concentric muscle force was decreased after SS and CS (all p < 0.05). On the other hand, concentric muscle force was unchanged after DS, while the decreases in surface electromyographic activities during concentric force measurements after all stretching methods were similar. Our results suggest that 300 sec of SS, DS, and CS have different acute and prolonged effects on flexibility and muscle force.

Acute Effects of Various Stretching Techniques on Range of Motion: A Systematic Review with Meta-Analysis

Background

Although stretching can acutely increase joint range of motion (ROM), there are a variety of factors which could influence the extent of stretch-induced flexibility such as participant characteristics, stretching intensities, durations, type (technique), and muscle or joint tested.

Objective

The objective of this systematic review and meta-analysis was to investigate the acute effects of stretching on ROM including moderating variables such as muscles tested, stretch techniques, intensity, sex, and trained state.

Methods

A random-effect meta-analysis was performed from 47 eligible studies (110 effect sizes). A mixed-effect meta-analysis subgroup analysis was also performed on the moderating variables. A meta-regression was also performed between age and stretch duration. GRADE analysis was used to assess the quality of evidence obtained from this meta-analysis.

Results

The meta-analysis revealed a small ROM standard mean difference in favor of an acute bout of stretching compared to non-active control condition (ES = −0.555; Z = −8.939; CI (95%) −0.677 to −0.434; p  < 0.001; I2 = 33.32). While there were ROM increases with sit and reach (P  = 0.038), hamstrings (P  < 0.001), and triceps surae (P  = 0.002) tests, there was no change with the hip adductor test (P  = 0.403). Further subgroup analyses revealed no significant difference in stretch intensity (P  = 0.76), trained state (P  = 0.99), stretching techniques (P  = 0.72), and sex (P  = 0.89). Finally, meta-regression showed no relationship between the ROM standard mean differences to age (R2 = −0.03; P  = 0.56) and stretch duration (R 2 = 0.00; P  = 0.39), respectively. GRADE analysis indicated that we can be moderately confident in the effect estimates.

Conclusion

A single bout of stretching can be considered effective for providing acute small magnitude ROM improvements for most ROM tests, which are not significantly affected by stretch intensity, participants’ trained state, stretching techniques, and sex.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-023-00652-x.

The meta-analysis on joint range of motion (ROM) increases revealed a small effect size in favor of an acute bout of stretching compared to the control condition. Subgroup analysis revealed a significant increase in ROM with sit and reach, hamstrings, and triceps surae tests, but no improvement with the hip adductor tests. Whereas all moderating variables presented significant increases in ROM, further subgroup analyses revealed no significant difference in ROM gains with the stretch intensity, trained state of the participants, stretching techniques, and sex. A meta-regression showed no relationship between the effect sizes to age and stretch duration, respectively.

Dynamic and static stretching on hamstring flexibility and stiffness: A systematic review and meta-analysis

INTRODUCTION

Hamstring injuries are one of the most common types of damage in sports. Insufficient flexibility and high stiffness are important reasons for it. Stretching is often used in warm-up activities before exercises to increase flexibility, among which dynamic stretching (DS) and static stretching (SS) are the most widely used. The effects of these two stretching techniques on the flexibility or stiffness of the hamstring still need to be clarified.

OBJECTIVE

This study aimed to compare the short-term, medium-term, and long-term effects of DS and SS on improving hamstring flexibility and stiffness via a meta-analysis of RCTs.

METHODS

RCTs were identified from PubMed, Cochrane Library, Web of Science, and PEDro from inception to July 28, 2022. The methodological quality was evaluated using the PEDro scale. The mean difference and 95% confidence interval of the outcome variables before and after stretching were calculated and the extracted data were quantitatively processed using a random or fixed effects model.

RESULTS

A total of 27 RCTs and 606 participants were included. In terms of improving the ROM of the hamstring, there was no significant difference in the acute (MD, -0.70, 95% CI, -1.54 to 0.14; Z = 1.63, P > 0.05) and sub-acute effects (MD, 1.71, 95% CI, -2.80 to 6.22; Z = 0.74, P > 0.05) between a single bout of SS and DS, while the acute (MD, -5.13, 95% CI, -7.65 to -2.61; Z = 3.99, P < 0.05) and sub-acute effects (MD, -5.30, 95% CI, -6.33 to -4.27; Z = 10.04, P < 0.05) of multiple bouts of SS was superior to DS; There was no significant difference in the medium-term effect between the two stretching techniques (MD, 3.48, 95% CI, -2.57 to 9.53; Z = 1.13, P > 0.05), but the long-term effect of SS was better than DS (MD, - 10.40, 95% CI, -10.97 to -9.83; Z = 35.57, P < 0.05). Regarding the length of the hamstring, the acute (MD, -0.41, 95% CI, -1.09 to 0.26; Z = 1.20, P > 0.05) and sub-acute effects (MD, -0.73, 95% CI, -1.69 to 0.22; Z = 1.51, P > 0.05) of a single bout of DS and SS were similar. Two studies have compared the effects on hamstring stiffness, with one showing similar effects, and the other showed that DS was superior to SS. One study showed no difference in the magnitude of change in improving passive torque. No studies explored the effect of DS and SS on hamstring myofascial length. Only one study demonstrated no significant difference in hamstring thickness.

CONCLUSIONS

A single bout of DS and SS have similar short-term effects in improving hamstring ROM and length, while multiple bouts of SS can significantly improve hamstring ROM compared to DS. DS and SS showed similar effects on hamstring myofascial length.

Potential Effects of Dynamic Stretching on Injury Incidence of Athletes: A Narrative Review of Risk Factors

The use of dynamic stretching as a replacement for static stretching in the warm-up is widespread based on the reports of static stretching-induced performance impairments. While acute and chronic static stretching has been reported to reduce musculotendinous injuries, especially with explosive and change of direction actions, the influence of dynamic stretching on injury incidence lacks a similar volume of literature for acute and chronic responses. It was the objective of this narrative review to examine the acute and training effects of dynamic stretching on injury incidence and possible moderating variables such as dynamic stretching effects on range of motion, strength, balance, proprioception, muscle morphology, and psycho-physiological responses. One study demonstrated no significant difference regarding injury incidence when comparing a dynamic stretching-only group versus a combined dynamic stretching plus static stretching group. The only other study examined functional dynamic stretching training with injured dancers and reported improved ankle joint stability. However, several studies have shown that dynamic activity with some dynamic stretching exercises within a warm-up consistently demonstrates positive effects on injury incidence. Regarding moderating variables, while there is evidence that an acute bout of dynamic stretching can enhance range of motion, the acute and training effects of dynamic stretching on strength, balance, proprioception, and musculotendinous stiffness/compliance are less clear. The acute effects of dynamic stretching on thixotropic effects and psycho-physiological responses could be beneficial for injury reduction. However, the overall conflicting studies and a lack of substantial literature compared with SS effects points to a need for more extensive studies in this area.

Effects of a warm-up intervention at the workplace on pain, heart rate, work performance and psychological perception among vineyard workers

OBJECTIVES

Warm-up sessions before physical activity are widely used in sports to help prevent injury and improve performance. Nowadays, companies assume that the effects observed in a sport context can be transferred to the workplace, particularly among workers exposed to biomechanical strain. Yet research on the use of warm-up interventions at the workplace is rather scarce and, when available, leads to conflicting results due to the low quality of the studies. To the best of our knowledge, there are no published studies to date assessing the effects of warm-up sessions among vineyard workers. The present study was designed to investigate if and how a single supervised warm-up session could be effective on perceived pain intensity, heart rate, work performance, and psychological perceptions among vineyard workers.

METHODS

A total of 31 vineyard workers completed a randomized crossover study at the workplace. They were observed in real work settings, i.e. during the pruning activity. Each participant performed the activity under two conditions: 1) with a warm-up session beforehand (WU) and 2) without any warm-up (NWU). Heart rate (HR) was assessed continuously before and during the warm-up, and during the first hour of pruning. Perceived pain intensity over fifteen anatomical locations was assessed before (T0) and immediately after (T1) warm-up, and after the first hour of work (T2). Readiness to work was assessed at T1. Work performance was assessed in terms of the number of completed tasks (number of pruned vines). Perceived work quality and perceived work ability were assessed at T2.

RESULTS

Perceived pain intensity over the lumbopelvic region was significantly higher at T2 than at T0, and at T2 than at T1, in both WU and NWU. Perceived pain intensity was not significantly different at T2 in WU and NWU. HR at T1 was significantly higher in WU than in NWU. Work performance, readiness to work, and perceived work ability were significantly higher in WU than in NWU.

CONCLUSION

This study showed that offering vineyard workers a supervised warm-up session at the workplace can lead to promising results where work performance and psychological perception are concerned.

Effects of Speed and Amplitude of Dynamic Stretching on the Flexibility and Strength of the Hamstrings

Dynamic stretching for more than 90 seconds is useful for improving muscle strength, although dynamic stretching for 30 seconds or less is commonly used in sports settings. The effects of dynamic stretching are influenced by the speed and amplitude of stretching, but no study examined these factors for 30 seconds of dynamic stretching. Therefore, the purpose of the present study was to examine the effects of speed (fast- or slow-speed) and amplitude (normal- or wide amplitude) of dynamic stretching for 30 seconds on the strength (peak torque during maximum isokinetic concentric contraction) and flexibility (range of motion, passive torque at maximum knee extension angle, and muscle-tendon unit stiffness) of the hamstrings. The passive torque and muscle-tendon unit stiffness reflect stretching tolerance and viscoelastic properties of the hamstrings, respectively. Fifteen healthy participants performed 4 types of 30 seconds of dynamic stretching. The muscle strength and flexibility were measured before and immediately after the dynamic stretching. The range of motion did not change after dynamic stretching at low speed and normal amplitude (p = 0.12, d = 0.59, 103.3%), but it was increased by other interventions (p < 0.01, d = 0.90-1.25, 104.5-110.1%). In all interventions, the passive torque increased (main effect for time, p < 0.01, d = 0.51 - 0.74, 111.0 - 126.9%), and muscle-tendon unit stiffness did not change. The muscle strength increased only after dynamic stretching at fast speed with normal amplitude (p < 0.01, d = 0.79, 107.1%). The results of the present study indicated that 30 seconds of dynamic stretching at fast speed and with normal amplitude can be beneficial for the measured parameters.

Effects of hot pack application before high-intensity stretching on the quadriceps muscle

Background/aims

High-intensity static stretching is assumed to increase the range of motion and/or decrease muscle stiffness; however, the effects of high-intensity static stretching on the quadriceps muscle have been debated. Hot pack application before high-intensity static stretching was assumed to decrease stretching pain, which is the main problem in high-intensity static stretching, and decrease quadriceps muscle stiffness. This study aimed to examine hot pack application before high-intensity static stretching on stretching pain, knee flexion range of motion, and quadriceps muscle stiffness.

Methods

In total, 21 healthy sedentary male participants randomly performed two interventions: high-intensity static stretching and hot pack application before stretching. Static stretching was performed at three 60-second stretching interventions with a 30-second interval. Then, a 20-minute hot pack was applied before high-intensity static stretching. The knee flexion range of motion and shear elastic modulus of the quadriceps muscle were measured by ultrasonic shear-wave elastography before and after the static stretching intervention.

Results

Stretching pain after hot pack application before stretching was lower than high-intensity static stretching alone. Significant increases were also found in knee flexion range of motion after both stretching interventions, but no significant difference was noted in the increase in the knee flexion range of motion with or without hot pack application. No significant change was found in quadriceps muscle stiffness in either intervention.

Conclusions

The results suggest that hot pack application before high-intensity static stretching could decrease stretching pain, but no significant difference in knee flexion range of motion increase was found.

Mechanisms underlying performance impairments following prolonged static stretching without a comprehensive warm-up

Whereas a variety of pre-exercise activities have been incorporated as part of a "warm-up" prior to work, combat, and athletic activities for millennia, the inclusion of static stretching (SS) within a warm-up has lost favor in the last 25 years. Research emphasized the possibility of SS-induced impairments in subsequent performance following prolonged stretching without proper dynamic warm-up activities. Proposed mechanisms underlying stretch-induced deficits include both neural (i.e., decreased voluntary activation, persistent inward current effects on motoneuron excitability) and morphological (i.e., changes in the force-length relationship, decreased Ca²⁺ sensitivity, alterations in parallel elastic component) factors. Psychological influences such as a mental energy deficit and nocebo effects could also adversely affect performance. However, significant practical limitations exist within published studies, e.g., long-stretching durations, stretching exercises with little task specificity, lack of warm-up before/after stretching, testing performed immediately after stretch completion, and risk of investigator and participant bias. Recent research indicates that appropriate durations of static stretching performed within a full warm-up (i.e., aerobic activities before and task-specific dynamic stretching and intense physical activities after SS) have trivial effects on subsequent performance with some evidence of improved force output at longer muscle lengths. For conditions in which muscular force production is compromised by stretching, knowledge of the underlying mechanisms would aid development of mitigation strategies. However, these mechanisms are yet to be perfectly defined. More information is needed to better understand both the warm-up components and mechanisms that contribute to performance enhancements or impairments when SS is incorporated within a pre-activity warm-up.

High-impact Routines to Ameliorate Trunk and Lower Limbs Flexibility in Women

Several types of routines and methods have been experimented to gain neuro/muscular advantages, in terms of overall range of motion, in athletes and fitness enthusiasts. The aim of the present study was to evaluate the impact of different routines on trunk- and lower limbs flexibility in a sample of young women. In a randomized-crossover fashion, eleven subjects underwent to: hamstrings stretching [S]; hamstrings stretching plus whole-body vibration [S+WBV]; partial-body cryotherapy [Cryo]; rest [Control]. Standing hamstrings stretch performance and sit-and-reach amplitude resulted to be improved with [S+WBV] compared to all other protocols (p<0.05). [Cryo] ameliorated the active knee extension performance with respect to all other interventions (p<0.05). These flexibility improvements were obtained without a loss in the trunk position sense proprioception. These results represent the first evidence that a single session of either vibration or cryotherapy can ameliorate flexibility without losing the trunk position sense proprioception in young women.