title: The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Evidence-based practice: beliefs, attitudes, knowledge, and behaviors of physical therapists. Frequent short rest breaks from computer work: effects on productivity and well-being at two field sites. Reliability of the PEDro scale for rating quality of randomized controlled trials. Increasing Hamstring Flexibility Decreases Lower Extremity Overuse Injuries in Military Basic Trainees Effect of static stretching on prevention of injuries for military recruits. Mechanical and physical responses to stretching with and without preisometric contraction in human skeletal muscle.
abstract: BACKGROUND AND PURPOSE 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 ) . SUBJECTS Ninety-three subjects ( 61 men , 32 women ) ranging in age from 21 to 39 years and who had limited hamstring muscle flexibility were r and omly 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 . METHODS Data were analyzed with a 5 x 2 ( group x test ) two-way analysis of variance for repeated measures on one variable ( test ) . RESULTS 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 . CONCLUSION AND DISCUSSION 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 BACKGROUND AND PURPOSE Little research has been done regarding the attitudes and behaviors of physical therapists relative to the use of evidence in practice . The purpose s of this study were to describe the beliefs , attitudes , knowledge , and behaviors of physical therapist members of the American Physical Therapy Association ( APTA ) as they relate to evidence -based practice ( EBP ) and to generate hypotheses about the relationship between these attributes and personal and practice characteristics of the respondents . METHODS A survey of a r and om sample of physical therapist members of APTA result ed in a 48.8 % return rate and a sample of 488 that was fairly representative of the national membership . Participants completed a question naire design ed to determine beliefs , attitudes , knowledge , and behaviors regarding EBP , as well as demographic information about themselves and their practice setting s. Responses were summarized for each item , and logistic regression analyses were used to examine relationships among variables . RESULTS Respondents agreed that the use of evidence in practice was necessary , that the literature was helpful in their practice s , and that quality of patient care was better when evidence was used . Training , familiarity with and confidence in search strategies , use of data bases , and critical appraisal tended to be associated with younger therapists with fewer years since they were licensed . Seventeen percent of the respondents stated they read fewer than 2 articles in a typical month , and one quarter of the respondents stated they used literature in their clinical decision making less than twice per month . The majority of the respondents had access to online information , although more had access at home than at work . According to the respondents , the primary barrier to implementing EBP was lack of time . DISCUSSION AND CONCLUSION Physical therapists stated they had a positive attitude about EBP and were interested in learning or improving the skills necessary to implement EBP . They noted that they needed to increase the use of evidence in their daily practice Computer operators at two work sites ( n = 73 , n = 19 ) were prompted to take three 30-s and one 3-min break from computer work each hour in addition to conventional rest breaks . Some operators were asked to perform stretching exercises during the short breaks . Mood state and musculoskeletal discomfort were assessed at each work site over a 2- or 3-week baseline period and a 4- or 6-week treatment period , respectively . Operator productivity measures were obtained from company records . Operators complied with about half of the added breaks but favoured 3-min breaks over 30-s breaks . No improvement in productivity or well-being was found at the larger work site . At the smaller work site , productivity , eye , leg and foot comfort all improved when the short breaks included stretching exercises . These results provide evidence that frequent short breaks from continuous computer-mediated work can benefit worker productivity and well-being when the breaks integrate with task dem and BACKGROUND AND PURPOSE Assessment of the quality of r and omized controlled trials ( RCTs ) is common practice in systematic review s. However , the reliability of data obtained with most quality assessment scales has not been established . This report describes 2 studies design ed to investigate the reliability of data obtained with the Physiotherapy Evidence Data base ( PEDro ) scale developed to rate the quality of RCTs evaluating physical therapist interventions . METHOD In the first study , 11 raters independently rated 25 RCTs r and omly selected from the PEDro data base . In the second study , 2 raters rated 120 RCTs r and omly selected from the PEDro data base , and disagreements were resolved by a third rater ; this generated a set of individual rater and consensus ratings . The process was repeated by independent raters to create a second set of individual and consensus ratings . Reliability of ratings of PEDro scale items was calculated using multirater kappas , and reliability of the total ( summed ) score was calculated using intraclass correlation coefficients ( ICC [ 1,1 ] ) . RESULTS The kappa value for each of the 11 items ranged from.36 to.80 for individual assessors and from.50 to.79 for consensus ratings generated by groups of 2 or 3 raters . The ICC for the total score was.56 ( 95 % confidence interval=.47-.65 ) for ratings by individuals , and the ICC for consensus ratings was.68 ( 95 % confidence interval=.57-.76 ) . DISCUSSION AND CONCLUSION The reliability of ratings of PEDro scale items varied from " fair " to " substantial , " and the reliability of the total PEDro score was " fair " to " good . The purpose of this intervention study was to prove that increasing flexibility of the hamstring musculotendinous unit would decrease the number of lower extremity overuse injuries that occur in military infantry basic trainees . Two different companies going through basic training at the same time were used . Hamstring flexibility was checked at the beginning and at the end of the 13-week infantry basic training course . The control company ( N 148 ) proceeded through normal basic training . The intervention company ( N 150 ) followed the same program but added three hamstring stretching sessions to their already scheduled fitness program . All subsequent lower extremity overuse injuries were recorded through the troop medical clinic . Hamstring flexibility increased significantly in the intervention group compared with the control group . The number of injuries was also significantly lower in the intervention group . Forty-three injuries occurred in the control group for an incidence rate of 29.1 % , compared with 25 injuries in the intervention group for an incidence rate of 16.7 % . Thus , in this study , the number of lower extremity overuse injuries was significantly lower in infantry basic trainees with increased hamstring flexibility This prospect i ve study was design ed to evaluate whether static stretching can prevent training-related injuries in Japan Ground Self-Defense Force military recruits . A total of 901 recruits between 1996 and 1998 were divided into two groups . Of which , 518 recruits were assigned to the stretching group and practice d static stretching before and after each physical training session . The  control subjects ( 383 recruits in the nonstretching group ) did not stretch statically prior to exercise . The static stretching consisted of 18 exercises . We collected injury data from medical records and assessed the incidence and the location of injury . The total injury rate was almost the same between two groups ; however , the incidences of muscle/tendon injury and low back pain were significantly lower in the stretching group ( p < 0.05 ) . Static stretching decreased the incidence of muscle-related injuries but did not prevent bone or joint injuries OBJECTIVE To examine electromyography ( EMG ) activity , passive torque , and stretch perception during static stretch and contract-relax stretch . DESIGN Two separate r and omized crossover protocol s : ( 1 ) a constant angle protocol on the right side , and ( 2 ) a variable angle protocol on the left side . SUBJECTS 10 male volunteers . INTERVENTION 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 . MAIN OUTCOME MEASURES Passive torque , joint range of motion , velocity , and hamstring EMG were continuously recorded . RESULTS 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 . CONCLUSION 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
target: RESULTS The physiological effects of stretches may contribute to reducing discomfort and pain .
  However , if other measures are not in place to remediate their causes , stretches may suppress awareness of risks , result ing in more debilitating injuries .
  If inadequately performed , stretches may also cause or aggravate injuries .
  The studies provided mixed findings , but demonstrated some beneficial effect of stretching in preventing work-related musculoskeletal disorders .
background: OBJECTIVE This article review ed the literature to clarify the physiological effects and benefits of , and misconceptions about , stretches used to reduce musculoskeletal disorders .