|
Brand: celine bag leopard, Eccentric Training and Static Stretching Improve Hamstring Flexibility of High School Males of Central Arkansas, Conway, ARContributed by Russell T. Nelson, PhD, hermes tray PT, SCS, ATC, contributed to conception and design; acquisition and analysis and interpretation of the data; and drafting, critical revision, and final approval of the article. William D. Bandy, PhD, PT, SCS, ATC, contributed jrrenterprises.com to conception and design; analysis and interpretation of the data; and drafting, critical revision, and final approval of the article.Address correspondence to Russell T. Nelson, PhD, PT, SCS, ATC, Orthopedic Specialists of Texarkana, 109 Georgian Terrace, Texarkana, AR 71854.AbstractObjective: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 Celine Bags Outlet week program of static stretching and with a control group (no stretching).Design and Setting:We used a test retest control group design celine online 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 loss of knee extension measured with the thigh held at 90 of hip flexion) were recruited for this study.Measurements:Hamstring flexibility was measured celine miami 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 and both the eccentric training (gain = 12.79 and static stretching (gain = 12.05 groups. No difference was found between the eccentric and static stretching groups. Ballistic stretching is a technique involving a rhythmic, bouncing motion. The bouncing uses the momentum of the extremity to lengthen the muscle. Proprioceptive neuromuscular facilitation involves the use of brief isometric contractions of the muscle to be stretched before statically stretching the muscle. Static stretching, considered the gold standard for measuring flexibility, is elongating a muscle to tolerance and sustaining the position for a length of time.6,8The literature reflects some interesting differences of opinion in commonly held beliefs regarding flexibility training and the consideration of static stretching as the gold standard. Murphy9 made a compelling argument against the use of static stretching. Although static stretching is often used as a part of preactivity preparation, Murphy9 argued that the nature of static stretching is passive and does nothing to warm a muscle; further, although the hamstring muscle is the most frequently stretched muscle, it is also the most commonly strained.Murphy9 suggested a better option for maintaining or increasing flexibility of a muscle is through active contractions using dynamic range of motion, thereby adding a fourth type of stretching. Dynamic range of motion is a technique that allows the muscle to elongate naturally and in its relaxed state. This elongation is achieved by having the subject concentrically contract the antagonist muscle to move the joint through the full available range in a slow, controlled manner to stretch the agonist muscle group. Murphy9 theorized that, as dynamic range of motion is performed, metabolic processes increase. These increases cause an increase in temperature that leads to decreased muscle viscosity and allows for a smoother contraction. This warmed muscle is more pliable and more accommodating to the forces placed on the muscle, leading to increased flexibility gains.Although Murphy's arguments regarding the use of dynamic range of motion to increase or maintain flexibility were interesting, Bandy et al10 found that, when comparing dynamic range of motion with static stretching, the flexibility gains achieved with a static stretching program were greater than those achieved in a dynamic range of motion program. Therefore, the gold standard for increasing flexibility is still considered static stretching. However, questions exist as to the effectiveness of static stretching in improving athletic performance.An activity that has not been addressed for achieving increased flexibility is eccentrically training the muscle through a full range of motion. For example, the hamstring muscles are most commonly injured when working eccentrically while decelerating or landing. Although earlier groups have examined dynamic range of motion, none have investigated the use of an eccentric agonist contraction to improve flexibility. Eccentrically training a muscle through a full range of motion theoretically could reduce injury rates and improve athletic performance and flexibility. Therefore, our purpose was to determine if high school males were able to improve hamstring flexibility after a 6 week eccentric exercise program and to compare the changes in hamstring flexibility occurring after the eccentric program with a 6 week program of static stretching and no exercises.METHODSSubjectsBefore data collection, we performed a power analysis to determine a priori the number of subjects needed to provide sufficient power to detect an interaction effect size of 0.40 for the 3 2 analysis of variance (ANOVA).12 Sixty three subjects were needed to provide power of 0.80 at an alpha of.05 with an r = 60. With this information in mind, we recruited 81 subjects on a volunteer basis to participate. We recruited 81 subjects to ensure that the appropriate number of subjects would complete the study, even with some attrition. Subjects were selected from a pool of high school students at Texarkana, Arkansas High School. A parent or guardian signed each subject's informed consent form, and the minor signed an informed assent form. The University of Central Arkansas Institutional Review Board approved the study and all forms.The volunteers met 4 requirements. First, the extremity to be tested had no history of impairment to the knee, thigh, hip, or lower back for 1 year before the study. Second, each subject exhibited tight hamstrings. Tight hamstrings were defined as a 30 knee extension deficit with the hip at 90 degrees as described by Bandy and Irion.13 Third, subjects not already involved in an exercise program for the trunk or lower extremities agreed not to start a program for the duration of the study. Fourth, subjects who already were participating in a regular exercise program agreed hermes men not to increase the frequency or intensity of their program for the 6 week training period.EquipmentHamstring flexibility was measured using a double armed goniometer of transparent plastic. The protractor of the goniometer was divided into 1 increments. The arms of the goniometer were 12 in (30.48 cm) in length. A bubble in an enclosed plastic container, typically used in a level, was affixed to the goniometer to help ensure maintenance of the hip at a 90 angle.Establishment of ReliabilityBefore data collection, we performed a reliability study on the technique celine luggage tote used to measure hamstring flexibility with the passive 90/90 test.14 Fifteen subjects from a sample of convenience with a mean age of 29.8 10.35 years (7 males, 8 females) were positioned supine with the hip and knee flexed to 90 The lateral epicondyle of the femur was palpated, and the goniometer was centered over it. The lateral malleolus of the tibia and the greater trochanter of the femur were then marked. The arms of the goniometer were aligned with the proximal and distal landmarks.Figure 1The 90/90 test for measuring hamstring flexibility.Terminal extension was determined as the point at which the researcher felt a firm resistance to the movement. Once terminal extension was reached, the researcher holding the goniometer ensured proper alignment and the blinded goniometer was revealed to the assisting examiner for the measurement to be read and recorded. Zero degrees of knee extension was considered full hamstring muscle flexibility. No warm up was allowed before data collection. Each subject was measured twice, with 30 minutes separating measurements.We found a mean of 20.80 10.07 from full knee extension for the first measurement and 21.0 10.22 for the second measurement. Using an intraclass correlation (3, 2), we calculated a reliability coefficient of.96, which was considered appropriate for proceeding with the study. celine bag leopard Numerous people An exciting new raising gimmick Tips about how needs to How will i celine bag leopard Would be these types of How frequently Would be likely to We |
|