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Stretching exercise volume for flexibility enhancement in secondary school children
Abstract
Aim:
The study aim was to establish the threshold of stretching volume for flexibility enhancement during physical education lessons in secondary school children.
Methods:
Subjects were 239 tenth grade children randomly assigned to four groups (boys 107, girls 132, mean age 15.1 ± 0.4). Children involved in after-school sports were not included in the study. Physical education lessons were performed twice a week for 45 minutes in duration. The intervention lasted for five weeks comprising 10 physical education lessons. Flexibility was determined from sit and reach test before and after intervention. Subjects in group 1 performed standard "sit and reach" test of four trials in every physical education lesson; in group 2 received one stretching exercise of four repetitions; group 3 received four stretching exercises of four repetitions; in group 4 no stretching was performed.
Results:
Flexibility improvement in group 3 were the greatest (21.6%; P<0.05), smaller in group 2 (12.6%, P<0.05) and smallest in 1 group (5.1%, P<0.05), while control group changes were insignificant (1.7%, P>0.05).
Conclusion:
The main finding was that single flexibility test performed twice a week for five weeks was sufficient stimulus to increase range of motion in secondary school children. Stretching exercises provides exceptional prospects to achieve youths' improvement since schoolchildren are very sensitive to flexibility training.
... The limiters of movement are bones. The shape of the bones largely determines the direction and scope of movements in the joint (flexion, extension, abduction, reduction, supination, pronation, rotation) (Kamandulis et al., 2013;Ospankulov et al., 2022). ...
... The flexibility indicators are significantly influenced by external conditions (Kamandulis et al., 2013;Lopes et al., 2017;Mărcuș et al., 2022): ...
... Flexibility as one of the main human abilities allows you to perform motor actions with the necessary range of movements (Moreira et al., 2012;Kamandulis et al., 2013;Mărcuș et al., 2022;Pérez Vigo et al., 2022). It characterizes the degree of mobility in the joints and the state of the muscular system. ...
The objective is to identify sensitive periods for the accentuated development of flexibility of schoolchildren. Methods: the scientific research was conducted on the basis of 60 schools in the city of Kirov, in Russia from September 14, 2022 to May 22, 2023. The pedagogical experiment involved 1,217 children (579 boys and 638 girls) from grades 1 to 11 of secondary school number 60 Kirov, Russia. Each lesson in the discipline "Physical education" lasted 40 minutes and took place 3 times a week. All students were engaged in the usual physical education program at school. All students took the tests at the beginning and at the end of the school year. The level of flexibility development was determined by the test "Leaning forward from a standing position on a gymnastic bench." Excel was used to process the results of the study, the Biostatistics-2022 program determined the reliability of the results of the T-Student study. Results: After the end of the study, the average indicators in each age group increased during the academic year. In the indicators of boys from the beginning to the end of the study, there was a significant and significant increase in flexibility indicators in the second grade (+15%), in the third grade (+17%) and in the fourth grade (+15%). In girls, a significant increase in the value is noted in the third grade (+16%), fifth grade (+14%) and sixth grade (+15%). In other age periods, there is not a significant increase in flexibility indicators (p>0.05). Conclusion: As a result of this large-scale study, it can be argued that the targeted development of flexibility should be in boys aged 8 to 11 years, and in girls aged 9-10 years, 11-12 years and 12-13 years. Keywords: Physical exercises, Joint mobility, Muscle stretching, Physical education.
... However, children at this age tend to have good flexibility. Nevertheless, daily stretching exercises can increase muscle flexibility and range of motion in joints [30]. Kamandulis et al. (2013) showed improved range of motion in children after five weeks of stretching exercises [30]. ...
... Nevertheless, daily stretching exercises can increase muscle flexibility and range of motion in joints [30]. Kamandulis et al. (2013) showed improved range of motion in children after five weeks of stretching exercises [30]. However, in TDG, the initial stretching warm-ups helped strengthen the children's flexibility, but in the CDG, the children did not do any activity to improve their flexibility. ...
... Nevertheless, daily stretching exercises can increase muscle flexibility and range of motion in joints [30]. Kamandulis et al. (2013) showed improved range of motion in children after five weeks of stretching exercises [30]. However, in TDG, the initial stretching warm-ups helped strengthen the children's flexibility, but in the CDG, the children did not do any activity to improve their flexibility. ...
A healthy and active lifestyle should start from an early age, as habits learned in childhood are more likely to endure. This study aimed to compare the effectiveness of child-designed games and teacher-designed games on the physical fitness and creativity of children aged 8-10 years. Thirty children participating in a sports club were randomly divided into two groups: teacher-designed games (TDG) and child-designed games (CDG). Subjects practiced two sessions per week for eight weeks, each session lasting 60 minutes. Fitness factors, such as strength, muscle endurance, aerobic fitness, agility, speed, and creativity were assessed by valid tests before and after the protocols. A repeated measure analysis of variance (ANOVA) was used to analyze the data. The TDG intervention led to a significant improvement in KTK (37.1% vs. -3.2%) and agility (-3.7% vs. -0.4%) compared to CDG intervention, while CDG intervention was associated with a significant improvement in aerobic capacity (10.1% vs. 3.6%) and in the elaboration of creativity test (23.3% vs. 8.6%). Both groups demonstrated substantial improvements in handgrip strength, static balance, long jump, flexibility, core endurance, and creativity tests, with no significant difference between groups. There were no significant changes in anthropometric features following the intervention. The implementation of combined teacher-designed and child-designed approaches in children's classrooms, in addition to promoting all aspects of physical fitness, may be effective in enhancing physical fitness and creativity.
... Thus, a total volume per session of at least 30-60 s seems to be recommended. Kamandulis et al. (2013) compared the effect of a stretching program performed with a volume per session of 4 x 2 s (8 s), 4 x 20 s (80 s) and 12 x 20 s (240 s). Although these authors found that the three groups found statistically significant improvement of hamstring extensibility, the students that performed a total of 240 s per session increased more than those who performed 80 s and 8 s. ...
... Regarding the stretching exercises, in the most studies stretching exercises were performed correctly sensing and locating the stretch, properly positioning the spine, with curvatures of the dorsal and lumbar spine within normality (except for Kamandulis et al., 2013, andVidal et al., 1995). The aligned column eliminates the increase in dorsal kyphosis that would be compensated for the limitation of the movement of the pelvis (Rodríguez & Santonja, 2001). ...
... Regarding the test protocol, only five studies used angular tests to assess students' hamstring extensibility (Nelson & Bandy, 2004;Reid & McNair, 2004;Sainz de Baranda, 2009;Useros & Campos, 2011;Van Rensburg & Coetzee, 2014). Due to the necessity of several instruments (i.e., a stretcher, Lumbosant or similar device, and a goniometer or inclinometer), two or more qualified evaluators, and time constraints, the use of these angular tests seem to be limited in several studies such as in the school setting (Becerra-Fernández et al., 2016;Kamandulis, Emeljanovas & Skurvydas 2013;Rodríguez et al., 1999;Rodríguez et al., 2008;Vidal, 1995). Since flexibility evaluation with goniometers and inclinometers are really sensitive methods, their use requires a certain technical qualification (Castro-Piñero et al., 2009). ...
The purpose of the present review was to examine the effects of Physical Education-based stretching programs on hamstring extensibility in high school students. Relevant studies were searched from 10 databases. The results suggested that students should performed stretching programs at least for a duration of 5-6 weeks, a frequency of twice a week, and a volume per session of 30-60 s (20-30 s per set) to obtain improvements on the hamstring extensibility. Stretching programs with higher duration, frequency and volume seems to obtain greater effects. Although the most studies obtained flexibility improvements using static techniques, dynamic stretching exercises performed in a controlled manner also produced improvements and they were safety. After a four-week detraining period, students reverted back to their baseline levels. Teachers should implement stretching programs to improve the students’ flexibility during the Physical Education classes.
... Regarding the magnitude effects of the intervention, the effect size of the 8-week development program was moderate-to-high. In contrast with these results, all the previous studies carrying out short-term PE-based stretching programs (5-10 weeks) obtained lower effect sizes, with a lowto-moderate median value (g=.43) (Kamandulis, Emeljanovas, & Skurvydas, 2013;Mayorga-Vega, Merino-Marban, Garrido, & Viciana, 2014a;Mayorga-Vega, et al., 2014b;Merino-Marban, et al., 2015;Sánchez Rivas, et al., 2014). On the other hand, the effect size of the two-minute-persession maintenance program carried out for four weeks was moderate. ...
... On the other hand, the effect size of the two-minute-persession maintenance program carried out for four weeks was moderate. Similarly to the current study, Kamandulis et al. (2013) found that, after a fiveweek development stretching program carried out twice a week, adolescents obtained a moderate improvement of hamstring extensibility, but small when the volume of stretching was reduced (80 s vs. 320 s of total stretching time). ...
The purpose of the present study was to examine the effects of a dynamic stretching development program followed by a four-week detraining period and maintenance program on hamstring extensibility in a physical education setting. A sample of 108 female high-school students aged 16-17 years from four classes were clustered randomly and assigned to either an experimental or a control group. During physical education sessions, the experimental group students performed a dynamic stretching program twice a week for eight weeks. Subsequently, after a four-week period of detraining, the experimental group students completed a maintenance program twice a week during four weeks. The results of the two-way analysis of variance showed that the physical education-based development program significantly improved students’ hamstring extensibility (p<.001). Although after four weeks of detraining students’ flexibility reverted to its baseline levels (p>.05), the gains obtained previously were recovered after a four-week maintenance program (p<.001). Hence, a physical education-based dynamic stretching intervention is effective in improving and maintaining hamstring extensibility among female high-school students. However, after four weeks of detraining, students’ flexibility reverts to its baseline levels. These findings could help and guide teachers to design programs that guarantee a feasible and an effective development of flexibility in a physical education setting.
... Regarding the magnitude effects of the development program, in the present study the effect size of the stretching development program was moderate, indicating that the intervention was effective. Similarly to the present results, all the previous studies carrying out short-term PE-based stretching programs obtained on average similar effect sizes (g = 0.43) (Kamandulis et al., 2013;Mayorga-Vega et al., 2014a;2014b;Merino-Marban et al., 2015;Sánchez Rivas et al., 2014). ...
... In regard to the duration of the stretching program, while the previous studies examining the short-term stretching programs effects (5-10 weeks) obtained similar effect sizes as the current study (g = 0.43, 0.24-0.67) (Kamandulis et al., 2013;Mayorga-Vega et al., 2014a;2014b;Merino-Marban et al., 2015;Sánchez Rivas et al., 2014), the magnitude was higher for the mid-term stretching programs (16 weeks) (g = 0.86, 0.85-0.88) (Coledam et al., 2012), and even higher for those with long-term stretching programs (whole school year, 31-32 weeks) (g = 0.94, 0.85-2.06) ...
The main purpose of the present study was to examine the effects of a physical education-based stretching development and maintenance program on hamstring extensibility in schoolchildren. A sample of 150 schoolchildren aged 7-10 years old from a primary school participated in the present study (140 participants were finally included). The six classes balanced by grade were cluster randomly assigned to the experimental group 1 (n = 51), experimental group 2 (n = 51) or control group (n = 49) (i.e., a cluster randomized controlled trial design was used). During the physical education classes, the students from the experimental groups 1 and 2 performed a four-minute stretching program twice a week for nine weeks (first semester). Then, after a five-week period of detraining coinciding with the Christmas holidays, the students from the experimental groups 1 and 2 completed another stretching program twice a week for eleven weeks (second semester). The students from the experimental group 1 continued performing the stretching program for four minutes while those from the experimental group 2 completed a flexibility maintenance program for only one minute. The results of the two-way analysis of variance showed that the physical education-based stretching development program significantly improved the students’ hamstring extensibility (p < 0.001), as well as that these gains obtained remained after the stretching maintenance program (p < 0.001). Additionally, statistically significant differences between the two experimental groups were not found (p > 0.05). After a short-term stretching development program, a physical education-based stretching maintenance program of only one-minute sessions twice a week is effective in maintaining hamstring extensibility among schoolchildren. This knowledge could help and guide teachers to design programs that allow a feasible and effective development and maintenance of students’ flexibility in the physical education setting.
... A total of 96 studies met the eligibility criteria and were included in the meta-analysis (Amado-Pacheco et al., 2019;Anselma et al., 2020;Armstrong et al., 2011;Ayán Pérez et al., 2020;Bae et al., 2015;Baquet et al., 2006;Bartkowiak et al., 2021;Batez et al., 2021;Benzo et al., 2023;Casajús et al., 2007;Chagas & Barnett, 2023;Chen et al., 2022;Cieśla et al., 2014;Cieśla et al., 2017;De la Cruz-Sánchez & Pino-Ortega, 2010;Deforche et al., 2003;Docherty & Bell, 1985;Eather et al., 2016;Estivaleti et al., 2022;Fang et al., 2017;Fiori et al., 2021;Flanagan et al., 2015;Fogelholm et al., 2008;Fortier et al., 2001;Godoy-Cumillaf et al., 2020;Golle et al., 2014;Gontarev et al., 2018;Gulías-González et al., 2014;Haapala et al., 2015;Haapala et al., 2016;Hands et al., 2009;Haugen et al., 2014;He et al., 2019;Henriques-Neto et al., 2022;Hong & Hamlin, 2005;Hsu et al., 2021;Huang & Malina, 2002;Jones et al., 2005;Jürimäe & Saar, 2003;Jürimäe & Volbekiene, 1998;Kamandulis et al., 2013;Karppanen et al., 2012;Katzmarzyk et al., 2000;Kidokoro et al., 2016;Kim & Park, 2017;Kondric et al., 2013;Koslow, 1987;Lehnhard et al., 1992;Lintu et al., 2016;Lo et al., 2017;Lovecchio, Giuriato, et al., 2019;Lovecchio et al., 2015;Lovecchio, Novak, et al., 2019;Mačak et al., 2022;Marshall et al., 1998;Martinho et al., 2022;McMillan & Erdmann, 2010;Moliner-Urdiales et al., 2010;Monyeki et al., 2005;Oja & Jürimäe, 1997Örjan et al., 2005;Ortega et al., 2008;Panczyk et al., 2014;Pelicer et al., 2016;Pissanos et al., 1983;Podstawski & Borysławski, 2012;Puszczałowska-Lizis et al., 2023;Richards et al., 2022;Riddoch et al., 1991;Runhaar et al., 2010;Ruzbarsky et al., 2022;Ryu et al., 2021;Sacchetti et al., 2012;Safrit & Wood, 1987;Santos et al., 2023;Sasayama & Adachi, 2019;Sember et al., 2022;Siegel et al., 1989;Smith & Miller, 1985;Sokolowski & Chrzanowska, 2012;Tishukaj et al., 2017;True et al., 2021;Tsimeas et al., 2005;Tsoukos & Bogdanis, 2021;Vanhelst et al., 2017;Veraksa et al., 2021;Vitali et al., 2019;Vlahov et al., 2014;Volbekiene & Griciūte, 2007;Welk et al., 2015;Weston et al., 2019;Xu et al., 2020;Zhang et al., 2021) The studies included a total of 408 effects from 944,420 children and adolescents (484,380 boys, 460,040 girls). The number of effects available by age and country are listed in Table 1. ...
... Furthermore, for children in general, static stretching exercises during warm-up reportedly affect their long-term flexibility, and dynamic stretching exercises during warm-up acutely affect their fitness performance. Several studies have reported on these findings [12][13][14] , but opinions are mixed. Many researchers are working on developing effective exercise protocols, but developing a muscle stretching exercise program is difficult because many exercise variation possibilities exist depending on how posture and movement are combined 15,16) . ...
Objective: Rapid bone development in growing children causes excessive tension in the lower extremities’ muscles and tendons, leading to reduced flexibility and increased musculoskeletal disorder risk. Further, lack of exercise causes obesity. Therefore, we created a stretching exercise protocol to prevent musculoskeletal disorders in elementary school (middle and upper grades) children during their growth period, when rapid bone development begins.
Patients and Methods: We examined the effects on pain, injury, and flexibility. Fifty-three (boys: 34, girls: 19) students in grades 3–5 (ages 9–11) performed the stretching exercises at school thrice a week for one year, and we compared the results before and a year after the intervention.
Results: A three-minute stretching exercise routine achieved an intensity of 4.6–4.9 metabolic equivalents (METs; equivalent to brisk walking). Obesity (P=1.000), flexibility problems (inability to bend forward [P=0.754] or squat problems [P=1.000]), bone/joint pain (P=1.000), and injury (P=1.000) did not significantly increase.
Conclusion: Stretching exercises during the growth period may help prevent childhood musculoskeletal disorders, obesity, and flexibility loss.
... The distance of this measurement was measured in centimeters using the S&R box to represent knee flexors and lower back flexibility. During the test, participants slowly moved their trunk forward as far as possible while their knees were kept straight, holding this position for approximately 2 s (Kamandulis et al., 2013). The best result of the two measurements was analyzed. ...
Introduction:
The physiological and structural alterations have been less reported in response to dynamic stretching (DS) or neurodynamic nerve gliding (NG). Accordingly, this study investigated the changes in fascicle lengths (FL), popliteal artery velocity, and physical fitness in response to a single bout of DS or NG.
Methods:
The study included 15 healthy young adults (20.9 ± 0.7 yrs) and 15 older adults (66.6 ± 4.2 yrs) who randomly performed three different interventions (DS, NG, and rest control) for 10 min and 3 days apart. The biceps femoris and semitendinosus FL, popliteal artery velocity, sit and reach (S&R), straight leg raise (SLR), and fast walking speed were measured before and immediately after the intervention.
Results:
After NG intervention, S&R was largely greater by 2 cm (1.2, 2.8 cm) and 3.4 cm (2.1, 4.7 cm) with largely increased SLR angles of 4.9° (3.7°, 6.1°) and 4.6° (3.0°, 6.2°) with all p < 0.001 for the older adults and young groups, respectively. A similar magnitude improvement in the S&R and SLR testing was also seen for both groups after DS (p < 0.05). Moreover, no changes were seen in FL, popliteal artery velocity, fast gait speed, and age effect following all three intervention occasions.
Conclusion:
Stretching with DS or NG immediately increased flexibility, which appeared to be largely due to changes in stretch tolerance rather than an increase in fascicle length. Furthermore, age dependency in response to stretching exercise was not seen in the present study.
... One limitation is that in this systematic review no comparisons were made between male and female participants because the studies including both males and females reported collective values for both sexes, with the exception of three studies [29,52,53]. Furthermore, no comparisons between athletic and non-athletic populations were performed because in the studies involving primary or secondary school students, extracurricular activities (e.g., sport participation) were not controlled for or were not reported. ...
... One limitation is that in this systematic review no comparisons were made between male and female participants because the studies including both males and females reported collective values for both sexes, with the exception of three studies [29,52,53]. Furthermore, no comparisons between athletic and non-athletic populations were performed because in the studies involving primary or secondary school students, extracurricular activities (e.g., sport participation) were not controlled for or were not reported. ...
Background
Flexibility is an important component of physical fitness for competitive and recreational athletes. It is generally suggested that flexibility training should start from childhood (6–11 years of age) to optimize joint range of motion (ROM) increases; however, evidence is limited and inconsistent.
Objective
To examine whether there is a difference in the effect of stretching training on flexibility during childhood (6–11 years of age) and adolescence (12–18 years of age).
Design
Systematic review and meta-analysis.
Methods
We searched PubMed Central, Web of Science, Scopus, Embase, and SPORTDiscus, to conduct this systematic review. Randomized controlled trials and non-randomized controlled trials were eligible. No language and date of publication restrictions were applied. Risk of bias was assessed using Cochrane RoB2 and ROBINS-I tools. Meta-analyses were conducted via an inverse variance random-effects model. GRADE analysis was used to assess the methodological quality of the studies.
Results
From the 2713 records retrieved 28 studies were included in the meta-analysis ( n = 1936 participants). Risk of bias was low in 56.9% of all criteria. Confidence in cumulative evidence was moderate. We found that stretching was effective in increasing ROM in both children (SMD = 1.09; 95% CI = 0.77–1.41; Z = 6.65; p < 0.001; I ² = 79%) and adolescents (SMD = 0.90; 95% CI = 0.70–1.10; Z = 8.88; p < 0.001; I ² = 81%), with no differences between children and adolescents in ROM improvements ( p = 0.32; I ² = 0%). However, when stretching volume load was considered, children exhibited greater increases in ROM with higher than lower stretching volumes (SMD = 1.21; 95% CI = 0.82–1.60; Z = 6.09; p < 0.001; I ² = 82% and SMD = 0.62; 95% CI = 0.29–0.95; Z = 3.65; p < 0.001; I ² = 0%, respectively; subgroup difference: p = 0.02; I ² = 80.5%), while adolescents responded equally to higher and lower stretching volume loads (SMD = 0.90; 95% CI = 0.47–1.33; Z = 4.08; p < 0.001; I ² = 83%, and SMD = 0.90; 95% CI = 0.69–1.12; Z = 8.18; p < 0.001; I ² = 79%, respectively; subgroup difference: p = 0.98; I ² = 0%).
Conclusions
Systematic stretching training increases ROM during both childhood and adolescence. However, larger ROM gains may be induced in childhood than in adolescence when higher stretching volume loads are applied, while adolescents respond equally to high and low stretching volume loads.
Registration: INPLASY, registration number: INPLASY202190032; https://inplasy.com/inplasy-2021-9-0032/
... Static stretching twice or more per week for several weeks increases sit-and-reach scores 9-43% [217][218][219][220][221][222][223][224][225] (Table 1). ...
Flexibility refers to the intrinsic properties of body tissues that determine maximal joint range of motion without causing injury. For many years, flexibility has been classified by the American College of Sports Medicine as a major component of physical fitness. The notion flexibility is important for fitness has also led to the idea static stretching should be prescribed to improve flexibility. The current paper proposes flexibility be retired as a major component of physical fitness, and consequently, stretching be de-emphasized as a standard component of exercise prescriptions for most populations. First, I show flexibility has little predictive or concurrent validity with health and performance outcomes (e.g., mortality, falls, occupational performance) in apparently healthy individuals, particularly when viewed in light of the other major components of fitness (i.e., body composition, cardiovascular endurance, muscle endurance, muscle strength). Second, I explain that if flexibility requires improvement, this does not necessitate a prescription of stretching in most populations. Flexibility can be maintained or improved by exercise modalities that cause more robust health benefits than stretching (e.g., resistance training). Retirement of flexibility as a major component of physical fitness will simplify fitness batteries; save time and resources dedicated to flexibility instruction, measurement, and evaluation; and prevent erroneous conclusions about fitness status when interpreting flexibility scores. De-emphasis of stretching in exercise prescriptions will ensure stretching does not negatively impact other exercise and does not take away from time that could be allocated to training activities that have more robust health and performance benefits.
... Flexibility of knee flexors muscle was evaluated by the sit and reach (S&R) method and passive straight leg raise (SLR) test. With the sit and reach box, participants moved their trunk forward as far as possible while the knee was kept straight, holding this position for approximately 2 s (Kamandulis et al. 2013). Best of two trials was recorded. ...
Purpose:
The purpose of this study was to compare the benefits and possible problems of 4 weeks stretching when taken to the point of pain (POP) and to the point of discomfort (POD).
Methods:
Twenty-six physically active women (20 ± 1.1 years) took part in group-based stretching classes of the hamstring muscles, 4 times per week for 4 weeks, one group one stretching to POD, the other to POP. Passive stiffness, joint range of motion (ROM), maximal isometric torque and concentric knee flexion torque, were measured before training and 2 days after the last training session.
Results:
Hip flexion ROM increased by 14.1° (10.1°-18.1°) and 19.8° (15.1°-24.5°) and sit-and-reach by 7.6 (5.2-10.0) cm and 7.5 (5.0-10.0) cm for POD and POP, respectively (Mean and 95% CI; p < 0.001 within group; NS between groups), with no evidence of damage in either group. Despite the large increases in flexibility there were no changes in either compliance or viscoelastic properties of the muscle tendon unit (MTU).
Conclusion:
Hamstrings stretching to POP increased flexibility and had no detrimental effects on muscle function but the benefits were no better than when stretching to POD so there is no justification for recommending painful stretching. The improvements in flexibility over 4 weeks of stretching training appear to be largely due to changes in the perception of pain rather than physical properties of the MTU although less flexible individuals benefited more from the training and increased hamstring muscle length.
... Previous studies have found that a PE-based stretching program, carried out twice a week, improves hamstring extensibility in schoolchildren (e.g. Kamandulis, Emeljanovas, & Skurvydas, 2013;Merino-Marban, Mayorga-Vega, Fernandez-Rodriguez, Vera Estrada, & Viciana, 2015). However, nowadays PE teachers must face several planningrelated problems for developing students' flexibility levels (Viciana, Mayorga-Vega, & Merino-Marban, 2014). ...
The purpose of this study was to examine the effects of a one-session-per-week stretching program on hamstring extensibility among schoolchildren in the physical education (PE) setting. Thirty seven 9-year-old schoolchildren from two classes were clustered and randomly assigned to an experimental group (n=19) or a control group (n=18). During PE classes, the experimental students performed a 3-minute stretching program once a week for the whole academic year (a total of 32 calendar weeks, but 28 weeks of intervention after
excluding holidays). Hamstring extensibility (estimated by the classic sit-and-reach test) was assessed at the beginning (week 0), in the middle (week 18) and at the end (week 34) of the stretching intervention program. The results of the two-way analysis of variance showed that the PE-based stretching program improved statistically significantly the students’ sit-and-reach scores in the middle and at the end of the intervention (p<.01). Since in PE many curricular contents need to be developed each academic year and the subject is also
restricted by its limited curriculum time allocation, teachers could improve students’ hamstring extensibility by only a one-session-per-week stretching program. Therefore, in addition to the improvement of students’ flexibility levels, this intervention program might permit regular development of other PE curricular contents. This knowledge could help and guide teachers to design programs that guarantee a feasible and effective development of flexibility in the PE setting.
... The measurements of ROM of the knee flexors muscle for flexibility evaluation were taken by the sit and reach (S&R) and passive straight leg raise (SLR) tests. With the sit and reach box, participants moved their trunk forward as far as possible, while the knee was kept straight, holding this position for approximately 2 s (Kamandulis et al. 2013). Best of two trials was recorded. ...
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.
... Previous studies examining the effect of a shortterm stretching program (5-10 weeks) carried out twice a week obtained similar or higher effect sizes than the current study (g = 0.24-0.67) [13][14][15]23,30,31 . Increasing training factors such as the frequency or duration of the intervention program could have a positive outcome on the magnitude effects. ...
Introduction: physical education teachers are required to carry out intervention programs for students to achieve
health-enhancing flexibility levels. Unfortunately, to our knowledge, there are no studies examining the effect of
a stretching program carried out only once a week on schoolchildren.
Objectives: the purpose of the present study was to compare the effects of a short-term stretching intervention
program performed once and twice a week on hamstring extensibility among schoolchildren in the physical education setting.
Methods: a sample of 180 high school students aged 12-14 years old was randomly assigned (by natural groups) to a control group, experimental group 1 and experimental group 2. During physical education classes,
experimental group students performed a stretching program for eight weeks. The experimental group 1 and 2
performed the stretching program once and twice a week, respectively.
Results: the analysis of variance results showed that the students of both experimental groups improved statistically significantly their hamstring extensibility when compared with the control group students (p < 0.01).
Nevertheless, no statistically significant differences between the two experimental groups were found
(p > 0.05).
Conclusions: a short-term stretching program performed only once a week improves hamstring extensibility in
schoolchildren. When the stretching program is performed twice a week, the improvement in students´ hamstring extensibility is not statistically higher.
57 Italian boys, born between 1998-2000 who play soccer and basketball in a non-professional club, underwent a physical examination in order to evaluate their growth and identify clinically latent or already present diseases that could predispose a danger during physical activity. The examination consisted in anthropometric measurements (weight, height and sitting height), genital examination and a screening for scoliosis, flexibility and proprioception. The goal of the examination was to make physical activity as safe as possible by minimizing the associated risks to health and prevent andrological diseases. Our findings support the necessity of seeing boys, beyond pre participation screening, involving parents and explaining them the worth of prevention.
This study examined whether contextual and personal motivational variables, taken from self-determination theory, could predict student cognitive and affective experiences in school physical education (PE), as well as participation in optional PE in the following school year. Structural equation modeling analysis with a sample of 302 British adolescents showed that need support provided by the PE teachers was related to student need satisfaction, which in turn predicted self-determined motivation. The latter predicted directly various motivational indices and indirectly future participation in optional PE. Furthermore, multivariate analysis of variance tests showed that those who opted for PE (n = 171), compared with those who did not (n = 131), reported more positive motivational experiences in the previous school year. The findings call for the promotion of self-determined motivation in PE in order to enhance student positive experiences and participation rates. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Warren B. Young, PhDUniversity of BallaratBallarat, Victoria, AustraliaDavid G. Behm, PhDMemorial University of NewfoundlandSt. John’s, Newfoundland, CanadaKeywords: warm-up; static stretching; strength and power.WARM-UP BEFORE PHYSICALactivity is a universally acceptedpractice with the objective ofpreparing the athlete physicallyand mentally for optimum perfor-mance and is believed to reducethe risk of injury and enhanceperformance (15, 25). Warm-upstypically contain 3 components:• A relatively low-intensity aero-bic component that is generalin nature such as submaxi-mum running. The rationalegiven for this is that it increas-es core and muscle tempera-ture, which improves neuro-muscular function (15, 22, 28).• Some stretching of the specificmuscles involved in the subse-quent activity. Some athletesmay spend 30 minutes orlonger systematically stretch-ing each muscle group. Thereare many variations of stretch-ing protocols such as proprio-ceptive neuromuscular facili-tation (PNF), static, anddynamic methods. Thesemethods are outlined thor-oughly in texts such as Alter(1) and Norris (22) and will notbe discussed in detail in thisstudy. Although the optimummethod for increasing flexibili-ty over a relatively long timemay be debatable, passive stat-ic stretching remains a popu-lar method used in a pre-exer-cise or precompetition warm-up routine. This usually in-volves moving a limb to the endof its range of motion (ROM)and holding it in the stretchedposition for 15–60 seconds(22). The objective of stretchingin a warm-up is usually toachieve a short-term increasein the ROM at a joint (8, 15,22) or to induce muscle relax-ation and therefore decreasethe stiffness of the muscle-ten-don system (7, 22).• Rehearsal of the skill about tobe performed. This is usuallyperformed at gradually in-creasing intensities, culminat-ing in some efforts that areequal to or greater than theexpected competition intensi-ty. This type of warm-upserves to activate or recruit thespecific muscle fibers andneural pathways required toachieve optimum neuromus-cular performance (15).Although the need for a warm-up before maximum effortstrength and power exercise israrely questioned, the precise pro-tocol leading to optimum perfor-mance is not well established. Thepurpose of this article is to discusswarm-up and, in particular, to re-view recent research that ques-tions the traditional use of staticstretching in a warm-up beforestrength and power activities. Forthe purpose of this discussion,strength is defined as the maxi-mum force produced in a staticmaximum voluntary contraction,relatively slow isokinetic contrac-tion, or the maximum weight lift-ed in a 1 repetition maximum test.Power activities are considered tobe any movements requiring sig-nificant amounts of both force andspeed, such as a vertical jump.
An objective of a warm-up prior to an athletic event is to optimize performance. Warm-ups are typically composed of a submaximal aerobic activity, stretching and a sport-specific activity. The stretching portion traditionally incorporated static stretching. However, there are a myriad of studies demonstrating static stretch-induced performance impairments. More recently, there are a substantial number of articles with no detrimental effects associated with prior static stretching. The lack of impairment may be related to a number of factors. These include static stretching that is of short duration (<90 s total) with a stretch intensity less than the point of discomfort. Other factors include the type of performance test measured and implemented on an elite athletic or trained middle aged population. Static stretching may actually provide benefits in some cases such as slower velocity eccentric contractions, and contractions of a more prolonged duration or stretch-shortening cycle. Dynamic stretching has been shown to either have no effect or may augment subsequent performance, especially if the duration of the dynamic stretching is prolonged. Static stretching used in a separate training session can provide health related range of motion benefits. Generally, a warm-up to minimize impairments and enhance performance should be composed of a submaximal intensity aerobic activity followed by large amplitude dynamic stretching and then completed with sport-specific dynamic activities. Sports that necessitate a high degree of static flexibility should use short duration static stretches with lower intensity stretches in a trained population to minimize the possibilities of impairments.
Many activities necessitate a high degree of static joint range of motion (ROM) for an extended duration. The objective of this study was to examine whether ROM could be improved with a short duration and volume of static stretching within a warm-up, without negatively impacting performance. Ten male recreationally active participants completed 2 separate protocols to examine changes in ROM and performance, respectively, with different warm-ups. The warm-up conditions for the ROM protocol were static stretching (SS), consisting of 6 repetitions of 6 s stretches; 10min of running prior to the SS (AS); and 5 min of running before and after the SS (ASA). The performance protocol included a control condition of 10min of running. Measures for the ROM protocol included hip flexion ROM, passive leg extensor tension, and hamstring electromyographic (EMG) activity at pre-warm-up, and at 1, 10, 20, and 30min post-warm-up. Performance measures included countermovement jump (CMJ) height, reaction time (RT), movement time (MT), and balance at pre-warm-up and at 1 and 10min post-warm-up. The ASA produced greater ROM overall than the SS and AS conditions (p< 0.0001), persisting for 30min. There were no significant alterations in passive muscle tension or EMG. For the performance protocol, there were no main effects for condition, but there was a main effect for time, with CMJ height being greater at 1 and 10min post-warm-up (p = 0.0004). Balance ratios and MT improved at 10min post-warm-up (p< 0.0001). Results indicate that the ASA method can provide ROM improvements for 30min with either facilitation or no impairment in performance. This may be especially important for athletes who substitute later into a game with minimal time for a full warm-up.
The purpose of this investigation was to determine which stretching technique, static or ballistic, is most effective for increasing hamstring muscle length when delivered at the same stretching dose over a 4-week training program. A single-blind, randomized controlled trial design was used in this investigation. Thirty-two participants (16 women and 16 men) between the ages of 18 and 27 years participated in the study. All participants who had a pre-training knee extension angle of less than 20° were excluded from the study. Subjects were randomly assigned to one of 3 groups: ballistic stretching, static stretching, or control group. Participants in the experimental stretching groups (ballistic and static stretching) performed one 30-second stretch 3 times per week for a period of 4 weeks. Statistical analysis consisted of a 2-way analysis of variance (group × sex) with an a priori alpha level of 0.05. No interaction between group and sex was identified (p = 0.4217). The main effect of sex was not statistically significant (p = 0.2099). The main effect for group was statistically significant at p < 0.0001. Post hoc analysis revealed that both static and ballistic stretching group produced greater increases in hamstring length than the control group. The static stretching group demonstrated a statistically greater increase in hamstring muscle length than the ballistic stretching group. No injuries or complications were attributed to either stretching program.
We compared the effect of the number of weekly repetitions of a static stretching program on the flexibility, hamstring tightness and electromyographic activity of the hamstring and of the triceps surae muscles. Thirty-one healthy subjects with hamstring tightness, defined as the inability to perform total knee extension, and shortened triceps surae, defined by a tibiotarsal angle wider than 90 degrees during trunk flexion, were divided into three groups: G1 performed the stretching exercises once a week; G2, three times a week, and G3, five times a week. The parameters were determined before and after the stretching program. Flexibility improved in all groups after intervention, from 7.65 +/- 10.38 to 3.67 +/- 12.08 in G1, from 10.73 +/- 12.07 to 0.77 +/- 10.45 in G2, and from 14.20 +/- 10.75 to 6.85 +/- 12.19 cm in G3 (P < 0.05 for all comparisons). The increase in flexibility was higher in G2 than in G1 (P = 0.018), while G2 and G3 showed no significant difference (G1: 4 +/- 2.17, G2: 10 +/- 5.27; G3: 7.5 +/- 4.77 cm). Hamstring tightness improved in all groups, from 37.90 +/- 6.44 to 29 +/- 11.65 in G1, from 39.82 +/- 9.63 to 21.91 +/- 8.40 in G2, and from 37.20 +/- 6.63 to 26.10 +/- 5.72 degrees in G3 (P < 0.05 for all comparisons). During stretching, a statistically significant difference was observed in electromyographic activity of biceps femoris muscle between G1 and G3 (P = 0.048) and G2 and G3 (P = 0.0009). No significant differences were found in electromyographic activity during maximal isometric contraction. Stretching exercises performed three times a week were sufficient to improve flexibility and range of motion compared to subjects exercising once a week, with results similar to those of subjects who exercised five times a week.
Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls.
A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova.
Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05).
Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes.
ACTRN12608000638336.
Static stretching (SS) is widely used in warm-ups before training and competition. A growing amount of research, however, has demonstrated that SS can impair muscle performance, leading to a reevaluation of optimal warm-up protocols. This commentary discusses many of the methodological issues that can influence conclusions about the acute effects of SS on performance. One difficulty in interpreting the literature is the lack of control or communication about the volume and intensity of the various stretching treatments used. Another major issue is the failure of many researchers to evaluate SS as it is used in practice, particularly the interaction with the other general and sport-specific components of the warm-up. Acute warm-up effects on performance should be considered in conjunction with potential effects on injury prevention. Future directions in research include optimizing general and sport-specific warm-ups, time course of physiological and performance effects, and individualization of warm-ups according to fitness and skill level.
Sixteen experienced male powerlifters served as subjects in a training study designed to examine the effect of flexibility training on: (i) the stiffness of the series elastic components (SEC) of the upper body musculature and (ii) rebound and purely concentric bench press performance. Nine of the subjects participated in two sessions of flexibility training twice per week for 8 wk. Prior to and after the training period the subjects' static flexibility, SEC stiffness, rebound bench press (RBP), and purely concentric bench press (PCBP) performance were recorded. The flexibility training induced a significant reduction in the maximal stiffness of the SEC. Furthermore, the experimental subjects produced significantly more work during the initial concentric portion of the RBP lift, enabling a significantly greater load to be lifted in the post-training testing occasion. The benefits to performance achieved by the experimental group consequent to flexibility training were greater during the RBP lift as compared with the PCBP lift. The control subjects exhibited no change in any variable over the training period. These results implied that the RBP performance enhancement observed consequent to flexibility training was directly caused by a reduction in SEC stiffness, increasing the utilization of elastic strain energy during the RBP lift.
To date, there are no reports comparing duration of static stretch in humans on joint range of motion (ROM) and hamstring muscle flexibility. The purpose of this study was to examine the length of time the hamstring muscles should be placed in a sustained stretched position to maximally increase ROM.
Fifty-seven subjects (40 men, 17 women), ranging in age from 21 to 37 years and with limited hamstring muscle flexibility (ie, 30 degrees loss of knee extension measured with femur held at 90 degrees of hip flexion), were randomly assigned to one of four groups. Three groups stretched 5 days per week for 15, 30, and 60 seconds, respectively. The fourth group, which served as a control group, did not stretch.
Before and after 6 weeks of stretching, flexibility of the hamstring muscles was determined by measuring knee extension ROM with the femur maintained in 90 degrees of hip flexion. Data were analyzed with a 4 x 2 analysis of variance (group x test) for repeated measures on one variable.
The data analysis revealed a significant group x test interaction, indicating that the change in flexibility was dependent on the duration of stretching. Further post hoc analysis revealed that 30 and 60 seconds of stretching were more effective at increasing flexibility of the hamstring muscles (as determined by increased ROM of knee extension) than stretching for 15 seconds or no stretching. In addition, no significant difference existed between stretching for 30 seconds and for 1 minute, indicating that 30 seconds of stretching the hamstring muscles was as effective as the longer duration of 1 minute.
The results of this study suggest that a duration of 30 seconds is an effective time of stretching for enhancing the flexibility of the hamstring muscles. Given the information that no increase in flexibility of the hamstring muscles occurred by increasing the duration of stretching from 30 to 60 seconds, the use of the longer duration of stretching for an acute effect must be questioned.
To examine electromyography (EMG) activity, passive torque, and stretch perception during static stretch and contract-relax stretch.
Two separate randomized crossover protocols: (1) a constant angle protocol on the right side, and (2) a variable angle protocol on the left side.
10 male volunteers.
Stretch-induced mechanical response in the hamstring muscles during passive knee extension was measured as knee flexion torque (Nm) while hamstring surface EMG was measured. Final position was determined by extending the knee to an angle that provoked a sensation similar to a stretch maneuver. Constant angle stretch: The knee was extended to 10 degree below final position, held 10sec, then extended to the final position and held for 80 sec. Variable angle stretch: The knee was extended from the starting position to 10 degrees below the final position, held 10sec, then extended to the onset of pain. Subjects produced a 6-sec isometric contraction with the hamstring muscles 10 degrees below the final position in the contract-relax stretch, but not in the static stretch.
Passive torque, joint range of motion, velocity, and hamstring EMG were continuously recorded.
Constant angle contract-relax and static stretch did not differ in passive torque or EMG response. In the final position, passive torque declined 18% to 21% in both contract-relax and static stretch (p<.001), while EMG activity was unchanged. In the variable angle protocol, maximal joint angle and corresponding passive torque were significantly greater in contract-relax compared with static stretch(p<.01), while EMG did not differ.
At a constant angle the viscoelastic and EMG response was unaffected by the isometric contraction. The variable angle protocol demonstrated that PNF stretching altered stretch perception.
Frequency and duration of static stretching have not been extensively examined. Additionally, the effect of multiple stretches per day has not been evaluated. The purpose of this study was to determine the optimal time and frequency of static stretching to increase flexibility of the hamstring muscles, as measured by knee extension range of motion (ROM).
Ninety-three subjects (61 men, 32 women) ranging in age from 21 to 39 years and who had limited hamstring muscle flexibility were randomly assigned to one of five groups. The four stretching groups stretched 5 days per week for 6 weeks. The fifth group, which served as a control, did not stretch.
Data were analyzed with a 5 x 2 (group x test) two-way analysis of variance for repeated measures on one variable (test).
The change in flexibility appeared to be dependent on the duration and frequency of stretching. Further statistical analysis of the data indicated that the groups that stretched had more ROM than did the control group, but no differences were found among the stretching groups.
The results of this study suggest that a 30-second duration is an effective amount of time to sustain a hamstring muscle stretch in order to increase ROM. No increase in flexibility occurred when the duration of stretching was increased from 30 to 60 seconds or when the frequency of stretching was increased from one to three times per day.
The purpose of this study was to examine the test-retest reliability and the criterion validity of a newly developed chair sit-and-reach (CSR) test as a measure of hamstring flexibility in older adults CSR performance was also compared to sit-and-reach (SR) and back-saver sit-and-reach (BSR) measures of hamstring flexibility. To estimate reliability, 76 men and women (M age = 70.5 years) performed the CSR on 2 different days, 2-5 days apart. In the validity phase of the study, scores of 80 men and women (M age = 74.2 years) were obtained on three field test measures of hamstring flexibility (CSR, SR, and BSR) and on a criterion test (goniometer measurement of a passive straight-leg raise). Results indicate that the CSR has good intraclass test-retest reliability (R = .92 for men; r = .96 for women), and has a moderate-to-good relationship with the criterion measure (r = .76 for men; r = .81 for women). The criterion validity of the CSR for the male and female participants is comparable to that of the SR (r = .74 and r = .71, respectively) and BSR (r = .70 and r = .71, respectively). Results indicate that the CSR test produces reasonably accurate and stable measures of hamstring flexibility. In addition, it appears that the CSR is a safe and socially acceptable alternative to traditional floor sit-and-reach tests as a measure of hamstring flexibility in older adults.
To characterise the time course of stress relaxation and recovery from stress relaxation in human ankles.
Two experiments were conducted. The first used a randomised within-subjects design, and the second used a randomised between-subjects regression design.
Several studies have described the time course of stress relaxation in human joints, but most have looked only at the effects of short durations of stretch. The time course of recovery from stretch in human ankles has not been documented.
In the first experiment, one ankle of each of eight subjects was stretched to a fixed dorsiflexion angle for 20 min. The ankle was then released for 2 min (during which time subjects either remained relaxed or performed isometric contractions), then stretched again. In a second experiment, on 24 subjects, the ankle was stretched for 20 min, then released between 0 and 20 min, then stretched again. In both experiments, subjects remain relaxed and ankle torque was measured continuously.
When a constant-angle stretch was applied to the ankle, torque declined bi-exponentially towards an asymptote that was 58% of the initial torque. Nearly 5 min of stretch were required to obtain half of the maximal possible stress relaxation. Torque had recovered by 43% within 2 min of the release of stretch, but the degree of recovery did not appear to depend on whether subjects remained relaxed or performed isometric contractions. The time course of recovery was similar to the time course of stress relaxation.
Long duration stretches are required to produce a large proportion of the maximal possible stress relaxation. Recovery is initially rapid when the stretch is released.
These data provide a description of the time course of the effects of stretch, and of the subsequent relief of stretch, on mechanical properties of human ankles.
Experimental pretest-posttest control design.
The purpose of the study was twofold: (1) to determine the lasting effect of static stretch on hamstring length for up to 24 hours and (2) to compare the efficacy of static stretch with and without warm-up exercise on hamstring length.
Research is limited on the lasting effects of static stretching and is controversial on the combined effects of warm-up activities and static stretching on muscle lengthening.
Fifty-six volunteer subjects (ages 18-42 years) with limited bilateral hamstring length were assigned to 1 of 4 groups: (1) warm-up and static stretch, (2) static stretch only, (3) warm-up only, and (4) control. The warm-up was 10 minutes of stair climbing at 70% of maximum heart rate. Static stretch consisted of a single session of three 30-second passive stretches of the hamstring. Hamstring length was measured preintervention and at several intervals postintervention (immediately and then at 15 minutes, 60 minutes, 4 hours, and 24 hours) using the active knee extension (AKE) test. Data were analyzed using a mixed-model analysis of variance.
The warm-up-and-static-stretch group and the static-stretch-only group showed a significant increase in hamstring length between preintervention and all postintervention measurements. At 24 hours poststretch, the warm-up-and-static-stretch group had a mean increase of 10.3 degrees (95% confidence interval, 7.7-12.9) and the static-stretch-only group had a mean increase of 7.7 degrees (95% confidence interval, 4.7-10.7) in AKE range of motion (ROM). Both of these groups did show significant decrease (2.9 degrees and 4.0 degrees, respectively) in hamstring muscle length (AKE ROM) at 15 minutes poststretch when compared to immediate poststretch values. The static-stretch-only and the warm-up-and-static-stretch groups did not differ significantly from each other. Control and warm-up-only groups showed no significant increase in hamstring length between preintervention and any of the postintervention measurements.
A significant increase in hamstring length can be maintained for up to 24 hours when using static stretching. Muscle length gains are greatest immediately after stretching and decline within 15 minutes. The addition of a warm-up exercise prior to stretching does not appear to significantly increase the effectiveness of static hamstring stretching.
The aim of this study was to determine whether an intensive stretch program increases muscle extensibility or subjects' tolerance to an uncomfortable stretch sensation. Twenty healthy able-bodied individuals with limited hamstring muscle extensibility were recruited. A within-subjects design was used whereby one leg of each subject was randomly allocated to the experimental condition and the other leg was allocated to the control condition. The hamstring muscles of each subject's experimental leg were stretched for 20 minutes each weekday for four weeks. Hamstring muscle extensibility (angle of hip flexion corresponding with a standardised torque) and stretch tolerance (angle of hip flexion corresponding with maximal torque tolerated) were assessed on both legs at the beginning and end of the study. The intervention did not increase the extensibility of the hamstring muscles (mean change in hip flexion was -1 degree, 95% CI -4 to 3 degrees) but did increase subjects' tolerance to an uncomfortable stretch sensation (mean change in hip flexion was 8 degrees, 95% CI 5 to 12 degrees). These results highlight the importance of distinguishing between real and apparent increases in muscle extensibility when assessing the effectiveness of stretch, and indicate that whilst a four-week stretch program increases subjects' tolerance to an uncomfortable stretch sensation it does not increase hamstring muscle extensibility.
The effect of static stretching intensity and duration on the flexibility of the hamstrings was investigated in 24 healthy male (mean age 32.2 years) and 24 healthy female (mean age 31.2 years) participated. Subjects were given a maximal-effort sit-and-reach test with each leg on Day 1. Subjects were then randomly assigned an intensity (60%, 85%, or 100% of baseline test value) and duration (10 seconds or 30-seconds) at which to train. Training took place on Days 2-7. Subjects were retested on Day 8. ANOVA and Newman-Keuls post hoc tests revealed that a duration of 30 seconds produced significantly greater flexibility than 10 seconds. The 85% and 100% intensities resulted in significantly greater flexibility than 60%. There were no significant differences between the 85% and 100% intensities. There were no gender differences in improvement. These results suggest that the higher duration (30 seconds) and intensity (85% and 100%) of stretching produce greater improvement in flexibility.
Forty-two female subjects were randomly assigned to one of six treatment groups or a control group. The six treatment groups received proprioceptive neuromuscular facilitation training for six consecutive days with isometric contraction periods of 0 sec, 3 sec, or 6 sec. Three of the treatment groups followed an active regime (concentric contraction of the agonists) and three a passive regime. All subjects were pretested for active flexibility on Day 1. They were also posttested after training on Day 6, and without training on Day 7. A two factor multivariate analysis of covariance with trend analysis on the period of isometric contraction factor indicated a significant positive linear trend for this factor, approximate F(2, 28) = 7.90, p < .002, together with a significant interaction between this linear trend and the active-passive regime factor, approximate F(2, 28) = 3.81, P < .034. Follow-up tests revealed that this interaction was due to larger gains in active flexibility being associated with longer periods of isometric contraction in the active groups, but not in the passive groups.
The aim of this study was to determine whether muscle stiffness measured in vivo was different between males and females. Distal displacement of the gastrocnemius medialis myotendinous junction was measured directly using ultrasonography during passive dorsiflexion in eight males and eight females (age range 19-28 years). Plantarflexion torque and myotendinous junction displacement were measured at 5° intervals, where 0° was with the foot at right angles to the tibia. Stiffness of the gastrocnemius medialis muscle was calculated between 0° and 25° of dorsiflexion, and defined as passive plantarflexion torque/distal displacement of the myotendinous junction (N m cm(-1)). Relative muscle stiffness was also calculated as distal displacement relative to resting muscle length, and as passive torque relative to plantarflexion maximal voluntary contraction torque. No significant gender difference was observed in passive dorsiflexion torque, or in passive torque/maximal voluntary torque throughout the range of motion. Distal displacement of the gastrocnemius myotendinous junction was 26% more in females than in males (P < 0.05). Myotendinous junction displacement was 5.0 ± 1.4% of resting gastrocnemius medialis length in females, and 3.9 ± 0.6% in males. Over 25° of passive dorsiflexion, gastrocnemius medialis muscle stiffness was greater in males than in females by 44% (P < 0.05). In conclusion, based on the in vivo assessment of myotendinous junction displacement, passive gastrocnemius medialis muscle stiffness is greater in males than in females.
Hamstring muscle strain represents a significant injury to the athlete participating in sporting activities. Lack of hamstring flexibility has been correlated to hamstring muscle injury. There is, however, conflict concerning the most efficient hamstring stretching technique. The purpose of this study was to compare static stretch (SS) and proprioceptive neuromuscular facilitation (PNF) hamstring stretching techniques while maintaining the pelvis in two testing positions: anterior pelvic tilt (APT) or posterior pelvic tilt (PPT). Two groups of 10 subjects were randomly assigned to either an APT or PPT position. Each subject then performed eight sessions using PNF on one leg and SS on the other leg while maintaining the pelvis in the assigned position. Hamstring flexibility was assessed with the hip positioned at 90 degrees while actively extending the knee, i.e., active knee extension test (AKET). A two-way ANOVA comparing stretching technique and pelvic position revealed that the APT group significantly increased hamstring flexibility (P = 0.0375). There was not a significant difference between SS or PNF stretching technique in the APT position. There was not a significant increase in hamstring flexibility in the PPT group with either stretching technique (P > 0.05). The results suggest that APT position was more important than stretching method for increasing hamstring muscle flexibility.
This article addresses the medical, scientific, and practical aspects of stretching. Sections include information on the physiology of flexibility and stretching, stretching versus warm-up, and the clinical evaluation of flexibility. Detailed instructions for numerous stretching exercises for the major muscle groups are provided. Techniques for proper stretching are included.
Most muscle stretching studies have focused on defin ing the biomechanical properties of isolated elements of the muscle-tendon unit or on comparing different stretching techniques. We developed an experimental model that was designed to evaluate clinically relevant biomechanical stretching properties in an entire muscle- tendon unit. Our objectives were to characterize the viscoelastic behavior of the muscle-tendon unit and to consider the clinical applications of these viscoelastic properties.
Rabbit extensor digitorum longus and tibialis anterior muscle-tendon units were evaluated using methods designed to simulate widely used stretching tech niques. Additionally, the effects of varying stretch rates and of reflex influences were evaluated. We found that muscle-tendon units respond viscoelastically to tensile loads. Reflex activity did not influence the biomechani cal characteristics of the muscle-tendon unit in this model.
Experimental techniques simulating cyclic stretching and static stretching resulted in sustained muscle-ten don unit elongations, suggesting that greater flexibility can result if these techniques are used in the clinical setting. With repetitive stretching, we found that after four stretches there was little alteration of the muscle- tendon unit, implying that a minimum number of stretches will lead to most of the elongation in repetitive stretching. Also, greater peak tensions and greater energy absorptions occurred at faster stretch rates, suggesting that the risk of injury in a stretching regimen may be related to the stretch rate, and not to the actual technique. All of these clinically important considera tions can be related to the viscoelastic characteristics of the muscle-tendon unit.
The relationship between hamstring flexibility and hamstring muscle performance has not been reported. The purposes of this study were 1) to determine the most effective stretching method for increasing hamstring flexibility and 2) to determine the effects of increasing hamstring flexibility on isokinetic peak torque. Nineteen subjects participated in this study. A two-way analysis of variance was used to compare two stretching techniques: proprioceptive neuromuscular facilitation stretch and static stretch. A one-way repeated measures analysis of variance was used to compare hamstring isokinetic values pre- and poststretching. No significant increase occurred (p < .05) in hamstring flexibility even though increases occurred with each technique: static stretch (+21.3%) and proprioceptive neuromuscular facilitation (+25.7%). Significant increases occurred in peak torque eccentrically at 60 degrees/sec (p < .05, +8.5%) and 120 degrees/sec (p < .05, +13.5%) and concentrically at 120 degrees/sec (p < .05, +11.2%). No significant increase occurred at 60 degrees/sec (p > .05, +2.5%). We concluded that increasing hamstring flexibility was an effective method for increasing hamstring muscle performance at selective isokinetic conditions. Further study is needed to determine if increasing hamstring flexibility will increase performance in closed kinetic chain activities.
Passive muscle stretch tests are common practice in physical therapy and rehabilitation medicine. However, the effects of stretching exercises are not well known. With an instrumental straight-leg-raising set-up the extensibility, stiffness, and electromyographic activity of the hamstring muscles have been experimentally determined and the effects of stretching exercises have been evaluated. Fourteen volunteers, aged 20 to 38 years (mean 27.3) were selected from a young healthy population with the toe-touch test (finger-ground distance greater than 0cm), and a straight-leg-raising angle about 80 degrees. According to usual standards the diagnosis was short hamstrings. One group of seven subjects was treated during 4 weeks with a daily home exercise program aimed at stretching the hamstrings, whereas the untreated group was used as a control. Instrumental straight-leg-raising was performed in the subjects of both groups. The significance of the differences between the mean values was determined with the Student's t-test. Comparison of the data obtained before and after the muscle stretching program showed a slight but significant increase in the extensibility of the hamstrings accompanied with a significant increase of the stretching moment tolerated by the passive hamstring muscles. However, the elasticity remained the same. It is concluded that stretching exercises do not make short hamstrings any longer or less stiff, but only influence the stretch tolerance.
Stretching exercises are either performed alone or with other exercises as part of the athlete's warm-up. The warm-up is designed to increased muscle/tendon suppleness, stimulate blood flow to the periphery, increase body temperature, and enhance free, coordinated movement. The purpose of this paper is to review the literature regarding stretching, with the aim of defining its role during the warm-up. Implications of stretching on muscle/tendon flexibility, minimizing injury, enhancing athletic performance, and generally preparing the athlete for exercise are discussed. Physiology applied to stretching is also discussed together with different related techniques and practical aspects. A proposed model stretching regime is presented based on the literature reviewed.
The search for the identification of the sensory apparatus encoding muscle pain sensation in humans is recounted. Basic neurophysiologic animal studies, leading to a description of slowly conducting afferent from muscle and definition of high threshold polymodal muscle nociceptors, and pioneer psychophysic human studies together with recent microneurographic experiments in humans are described. The phenomena of muscle pain broad localization and distant referral are discussed, and clinical implications are extrapolated to interpret muscle pain as a localizing sign of mononeuropathy or radiculopathy. The identification of human muscle nociceptors has defined the scientific standard to test emerging clinical descriptions having muscle pain as a symptom.
To evaluate the effects of one 10-minute stretch on muscle stiffness in subjects with short hamstrings.
Randomized control trial.
Laboratory for human movement sciences in the department of rehabilitation of a university hospital.
Sixteen students from the Department of Human Movement Sciences participated with informed consent in the experiment. Subjects were limited to men and women without a history of neurological and orthopedic disorders. To select subjects with short hamstrings, the finger-ground distance had to be greater than 0cm (unable to touch the floor when bending forward) and the manual leg lifting was not to exceed 80 degrees. One group of 10 subjects performed static stretching exercises during 10 minutes interspersed with relaxing, whereas the untreated group of 6 subjects was used as a control.
The instrumental straight-leg-raising set-up enables the measurement of the force needed to lift the leg, range of motion (ROM), pelvic-femoral angle, and the electromyogram of the hamstrings. These variables provide information about the stiffness, elongation, and state of activity of the hamstring muscles. RESULTS. One 10-minute sport stretch resulted in a significant increase in passive muscle moment, ROM, and elongation of the hamstrings. There was no significant change in the course of the passive muscle stiffness curve with respect to the prestretch stiffness curve.
One session of static stretching does not influence the course of the passive muscle stiffness curve. The increased ROM, i.e., the extensibility of the hamstrings, results from an increase in the stretch tolerance.
Although passive stretching is widely used, the parameters of stretching necessary to achieve a lasting length have not been determined. This study investigated the lasting effects of one bout of two 15-second passive stretches on ankle dorsiflexion range of motion. Conducting this study was important because, while it focused on a sufficient minimum duration, it considered lengthening mechanisms thought to contribute to a lasting length. Nineteen healthy volunteers with symmetrical limitations of ankle dorsiflexion participated. Stretching was done in unilateral standing with the subject's heel suspended over the edge of a platform. Four 5-second active dorsiflexion contractions were used as a preconditioning intended to stabilize the effects of mechanisms providing temporary length gains and were found to be effective. Measurements of passive dorsiflexion range of motion were taken over 24 hours. This study found no statistically significant length gains using a single bout of two 15-second stretches. These data do not provide evidence of lasting lengthening at this duration. Further research to determine a minimum one-bout lasting length duration is encouraged.
The present study measured passive resistance to stretch in the hamstring muscles during a standardized stretch maneuver to estimate tensile forces and energy of the individual hamstring muscles in 7 flexible and 6 inflexible persons defined according to joint range of motion. Using a dynamometer, knee joint moment was measured during slow passive knee extension to a maximal angle (dynamic phase) followed by a 90-s static phase. Cross-sectional areas (CSA) of the separate hamstring muscles were obtained with magnetic resonance (MR) imaging. Mathematical modeling was used to calculate instantaneous muscle length and joint moment arm for each muscle. Subsequently, passive muscle tension (N/cm2) was calculated based on moment arm lengths, knee joint moments, and CSA. Maximal tolerated joint angle was greater in flexible (delta1.30+/-0.06 rad) than inflexible (delta0.84+/-0.06 rad) subjects, P<0.01. The peak tension at maximal angle was greater in flexible (81.8+/-12.5 N/cm2) than inflexible subjects (29.3+/-4.1 N/ cm2), P<0.001. For the separate muscles the overall change in muscle length (delta cm) and moment arm (delta cm) differed between groups, P<0.01. Similarly, muscle stiffness (delta tension/delta muscle length) was greater in flexible than inflexible subjects in the final 3 cm, P<0.01, and in the final 20% of length change, P<0.01. Absorbed energy (mJ/cm2) was greater in flexible than inflexible subjects in the final 40% of length change, P<0.05. These data show that flexible persons can attain a greater angle of stretch with an accompanying greater tensile stress and energy than inflexible persons due to an apparent greater tolerance to the externally applied load, and larger change in moment arm. The obtained stress data appear to be in the toe region of a 'classical' stress-strain curve, and energy rather than stiffness may therefore be more appropriate to analyze during the stretch procedure.
This investigation determined the effects of a static stretching program with different stretching protocols on the flexibility and passive resistance of the hamstrings of young adults. Forty healthy subjects (24 males and 16 females) aged 18 to 30 years were randomly assigned to one of four groups. The two training groups underwent static stretch training of the hamstrings either with a four-week protocol or with an eight-week protocol. The other two groups acted as control groups. A significant increase in flexibility of hamstrings was found in both of the two training groups (P<0.05). No difference was found in the range of motion gained between the two training groups. An increase in passive resistance at the corresponding maximal joint angle was only demonstrated in the four-week training group (P<0.05). Both protocols are effective in terms of improving flexibility of hamstrings. However, if injury is reduced when there is relatively lower passive resistance at the end-of-range, then the eight-week training regimen would be recommended.
To study the effects of a muscle stretching regimen for the rectus femoris muscle on subjective stretch sensation and range of motion (ROM).
A 2 x 2 crossover design comprising 2 treatments and 2 intervention periods.
A military base in Sweden.
A volunteer sample of 29 male military conscripts divided into 2 groups, with each group subjected to both experimental and control treatments at different time periods.
Two weeks of supervised stretching (4 times/wk) of the rectus femoris muscle (experimental treatment) and the calf muscles (control treatment).
Subjective rating of the stretch sensation for the anterior aspect of the thigh determined on a category ratio scale. Passive knee flexion ROM determined on each test with the same applied torque, specific for each subject.
An additive analysis of variance revealed that the stretch sensation after the experimental treatment was decreased, compared with the control treatment (p <.01). The knee flexion, however, remained the same regardless of the treatment.
Sensory adaptation seems to be an important mechanistic factor in the effect stretching has on ROM changes. The lack of change in knee flexion suggests that the stretching, as performed in this study, did not influence stiffness of the rectus femoris muscle. Sensory adaptation may also be an underlying mechanism in the alleviating effect of stretching when applied to tired, tender, and painful muscles.
To determine the contributions of neural and mechanical mechanisms to the limits in the range of motion (ROM) about a joint, we studied the effects of 30 sessions of static stretch training on the characteristics of the plantar-flexor muscles in 12 subjects. Changes in the maximal ankle dorsiflexion and the torque produced during passive stretching at various ankle angles, as well as maximal voluntary contraction (MVC) and electrically induced contractions, were recorded after 10, 20, and 30 sessions, and 1 month after the end of the training program. Reflex activities were tested by recording the Hoffmann reflex (H reflex) and tendon reflex (T reflex) in the soleus muscle. Training caused a 30.8% (P < 0.01) increase in the maximal ankle dorsiflexion. This improved flexibility was associated (r(2) = 0.88; P < 0.001) with a decrease in muscle passive stiffness and, after the first 10 sessions only, with a small increase in passive torque at maximal dorsiflexion. Furthermore, both the H- and T-reflex amplitudes were reduced after training, especially the latter (-36% vs. -14%; P < 0.05). The MVC torque and the maximal rate of torque development were not affected by training. Although the changes in flexibility and passive stiffness were partially maintained 1 month after the end of the training program, reflex activities had already returned to control levels. It is concluded that the increased flexibility results mainly from reduced passive stiffness of the muscle-tendon unit and tonic reflex activity. The underlying neural and mechanical adaptation mechanisms, however, showed different time courses.
To determine if submaximal contractions used in contract-relax proprioceptive neuromuscular facilitation (CRPNF) stretching of the hamstrings yield comparable gains in hamstring flexibility to maximal voluntary isometric contractions (MVICs).
Randomised controlled trial. A convenience sample of 72 male subjects aged 18-27 was used. Subjects qualified by demonstrating tight hamstrings, defined as the inability to reach 70 degrees of hip flexion during a straight leg raise. Sixty subjects were randomly assigned to one of three treatment groups: 1, 20% of MVIC; 2, 60% of MVIC; 3, 100% MVIC. Twelve subjects were randomly assigned to a control group (no stretching). Subjects in groups 1-3 performed three separate six second CRPNF stretches at the respective intensity with a 10 second rest between contractions, once a day for five days. Goniometric measurements of hamstring flexibility using a lying passive knee extension test were made before and after the stretching period to determine flexibility changes.
Paired t tests showed a significant change in flexibility for all treatment groups. A comparison of least squares means showed that there was no difference in flexibility gains between the treatment groups, but all treatment groups had significantly greater flexibility than the control group.
CRPNF stretching using submaximal contractions is just as beneficial at improving hamstring flexibility as maximal contractions, and may reduce the risk of injury associated with PNF stretching.
OBJECTIVE: To determine if the flexibility of high-school-aged males would improve after a 6-week eccentric exercise program. In addition, the changes in hamstring flexibility that occurred after the eccentric program were compared with a 6-week program of static stretching and with a control group (no stretching). DESIGN AND SETTING: We used a test-retest control group design in a laboratory setting. Subjects were assigned randomly to 1 of 3 groups: eccentric training, static stretching, or control. SUBJECTS: A total of 69 subjects, with a mean age of 16.45 +/- 0.96 years and with limited hamstring flexibility (defined as 20 degrees loss of knee extension measured with the thigh held at 90 degrees of hip flexion) were recruited for this study. MEASUREMENTS: Hamstring flexibility was measured using the passive 90/90 test before and after the 6-week program. RESULTS: Differences were significant for test and for the test-by-group interaction. Follow-up analysis indicated significant differences between the control group (gain = 1.67 degrees ) and both the eccentric-training (gain = 12.79 degrees ) and static-stretching (gain = 12.05 degrees ) groups. No difference was found between the eccentric and static-stretching groups. CONCLUSIONS: The gains achieved in range of motion of knee extension (indicating improvement in hamstring flexibility) with eccentric training were equal to those made by statically stretching the hamstring muscles.