Dynamic Back Extension Research Articles

Effect of a Core Conditioning Intervention on Tests of Trunk Muscular Endurance in School-Aged Children

Trunk and core muscular development has been advocated to increase athletic performance and for maintenance of musculoskeletal health, especially related to the prevention of low back pain (LBP). The purpose of this study was to examine the effects of a simple core conditioning routine on tests of trunk and core muscular endurance in school-aged children. Participants included 164 students (86 girls, 78 boys; mean age, 11.5 ± 2.5 years) recruited from a grade school in a metropolitan area located in the southwestern United States. Students performed an equipment-free, moderate-to-high intensity, dynamic core conditioning warm-up routine once a week for a period of 6 weeks during the start of their physical education classes. The intervention consisted of 10 different dynamic core conditioning exercises performed at a 30-second duration per exercise totaling 5 minutes per session. Pre- and post-assessments of muscular endurance consisted of 5 different trunk and core muscular endurance tests: Parallel Roman Chair Dynamic Back Extension, Prone Plank, Lateral Plank, Dynamic Curl-Up, and Static Curl-up. A generalized estimation equation was used to analyze differences in pre- and post-intervention muscular fitness assessments controlling for gender and grade level. Analysis of the data revealed significant increases in muscular fitness test performance for each of the 5 measured outcomes (p < 0.001). Because risk factors of LBP are thought to commence during childhood, results of this study suggest that it may be desirable for children and adolescents to perform moderate-to-high intensity dynamic core exercises during physical education warm-up to improve trunk and core muscular endurance.

The effects of back extension training on back muscle strength and spinal range of motion in young females.

The objective of this study was to determine the effects of a 10-week dynamic back extension training programme and its effects on back muscle strength, back muscle endurance and spinal range of motion (ROM) for healthy young females. Seventy-three young females (age: 19.32±1.80 years, height: 158.89±4.71 cm, body weight: 55.67±6.30 kg) volunteered for the study. Prior to the training period, all participants completed anthropometric measurements, back muscle strength and endurance test, lateral bending and spinal ROM measurements. After measurements, the participants were divided into two groups. The exercise group (N:35) performed the dynamic back extension exercise 3 days per week for 10 weeks. The control group (N:38) did not participate in any type of exercise. The mixed design ANOVA (group x time) was used to determine the difference in pre- and post-training values. The present findings show that there were significant differences between pre-training and post-training values for back muscle strength and spinal ROM in the exercise group. Following the dynamic strength training programme, back muscle strength and spine ROM values except flexion of the lumbar 5-sacrum 1 (L5-S1) segment of the exercise group showed a significant increase when compared with the pre test values. The control group did not show any significant changes when compared with the pre-training values. The results demonstrate that the 10-week dynamic strength training programme was effective for spinal extension ROM and back muscle strength, but there was no change in back muscle endurance. In this context, this programme could potentially be used to prevent the decrease of spinal ROM as well as provide an increase in the fitness parameters of healthy individuals.

Predictive Validity of Health-Related Fitness Tests on Back Pain and Related Disability: A 6-Year Follow-Up Study Among High-Functioning Older Adults

Back pain and related disability seem to be increasing among older adults. Health-related fitness tests have been developed to identify individuals at risk for mobility difficulties. However, poor fitness as a risk factor for back problems has seldom been studied. The purpose of the current study was to investigate whether performance in fitness tests predicts back pain and related disability during 6 years of follow-up. Study population consisted of community-dwelling men and women, born 1927 to 1941, who participated in assessment of health-related fitness and reported no long-term back pain or related disability at baseline (n = 517). The assessment included measurements of body mass index (BMI), one-leg stand, backward tandem walk, trunk side-bending, dynamic back extension, forward squat, 6.1-m walking speed and 1-km walk time. Prospective analyses indicated that poor fitness (poorest-third) in one-leg stand and trunk side-bending tests were the most powerful predictors of back pain. Regarding disability, poor fitness in dynamic back extension and overweight in terms of BMI ≥ 27 increased the risk. Tests of balance, trunk flexibility and trunk muscle endurance, as well as BMI can be implemented as screening tools for identifying persons with increased risk of back pain and related disability.

Pelvic Stabilization and Semisitting Position Increase the Specificity of Back Exercises

To examine the effect of pelvic stabilization and two lower-limb configurations on the EMG activity of back and hip extensor muscles during a dynamic back extension exercise on a machine and to compare them between sexes. Twenty-two healthy volunteers (11 men and 11 women) performed five trunk flexion-extension cycles at 40% of their maximal voluntary contraction (MVC) in a machine designed for back exercise. Two different positions were used: 1) seated position (seat horizontal, knees at 90 degrees ) and 2) semisitting position (seat slightly tilted forward at 15 degrees , knees at 45 degrees of flexion). In each position, three pelvic stabilization conditions were tested: 1) unrestrained (control condition), 2) partially restrained (posteriorly), and 3) totally restrained (posteriorly and anteriorly). EMG signals were recorded bilaterally with 12 pairs of electrodes placed on back muscles as well as on the gluteus maximus and biceps femoris. The muscular activation level, that is, the percentage of EMG amplitude relative to the maximal EMG obtained from MVC, was used to asses the relative contribution of each muscle group across exercises. In both sexes, two main results were found: 1) pelvic stabilization (partially and totally restrained) significantly (P < 0.05) increased the activity of all back muscles (average of 12%) and 2) semisitting position significantly decreased (range = 8-27%) the activity of two hip extensors compared with the seated position. Sex differences were also observed relative to the activity of some back muscles as well as the biceps femoris. Combining pelvic stabilization and semisitting position in back exercise machines might be a useful way to localize the effects of endurance training at the back muscles and this in both the sexes.

Health-related fitness tests as predictors of difficulties in long-distance walking among high-functioning older adults

Health-related fitness (HRF) tests are valid predictors of self-reported mobility difficulties among high-functioning older adults. The aim of the present study was to identify optimal cut-off values for HRF tests predicting self-reported difficulties in walking 2 km (WD). Subjects were 55- to 69-year-old men and women who were free of WD at baseline. The HRF assessment in 1996 included seven test items, and postal questionnaires were used to assess occurrence of new WD in 2002. Analysis of covariance and receiver-operating characteristic analysis were used as statistical methods. In a 1-km walk, the sensitivity and specificity at the optimal cut-off 10:15 (min:s) for men were 63% and 75%, and at the cut-off 10:47 for women 70% and 71%. In dynamic back extension, the sensitivity and specificity at the optimal cut-off 16.5 (repetitions) were 67% and 65% in men and 82% and 59% at cut-off 13.5 in women. Correspondingly, in backward walking, the sensitivity and specificity at the optimal cut-off 27.7 (seconds) were 65% and 69% in men and 74% and 61% at cutoff 35.0 in women. The 1-km walk, dynamic back extension and backward walking tests had the best predictive value for WD. These tests, with identified cut-off values, can be used to screen individuals who are at increased risk of WD. Tests can also be used in physical activity counseling to target activity to those components of HRF that indicate poor fitness and are important for good walking ability.

Predictive value of health-related fitness tests for self-reported mobility difficulties among high-functioning elderly men and women

The functional independence of elderly populations deteriorates with age. Several tests of physical performance have been developed for screening elderly persons who are at risk of losing their functional independence. The purpose of the present study was to investigate whether several components of health-related fitness (HRF) are valid in predicting the occurrence of self-reported mobility difficulties (MD) among high-functioning older adults. Subjects were community-dwelling men and women, born 1917-1941, who participated in the assessment of HRF [6.1-m (20-ft) walk, one-leg stand, backwards walk, trunk side-bending, dynamic back extension, one-leg squat, 1-km walk] and who were free of MD in 1996 (no difficulties in walking 2- km, n=788; no difficulties in climbing stairs, n=647). Postal questionnaires were used to assess the prevalence of MD in 1996 and the occurrence of new MD in 2002. Logistic regression analysis was used as the statistical method. Both inability to perform the backwards walk and a poorer result in it were associated with risk of walking difficulties in the logistic model, with all the statistically significant single test items included. Results of 1-km walk time and one-leg squat strength test were also associated with risk, although the squat was statistically significant only in two older birth cohorts. Regarding stair-climbing difficulties, poorer results in the 1-km walk, dynamic back extension and one-leg squat tests were associated with increased risk of MD. The backwards walk, one-leg squat, dynamic back extension and 1-km walk tests were the best predictors of MD. These tests are recommended for use in screening high-functioning older people at risk of MD, as well as to target physical activity counseling to those components of HRF that are important for functional independence.

Changes in physical performance among high-functioning older adults: a 6-year follow-up study.

Purposes of the study were (1) to investigate changes in physical performance during 6years follow-up among high-functioning older adults and (2) to describe the selection of study sample with reference to measured performance. Subjects (n=1,133) born during 1917-1941 participated in the battery of health-related fitness (HRF) tests (6.1-m walk, stair climbing, backwards walk, trunk side-bending, dynamic back extension, 1-km walk and body mass index) in 1996. Six hundred and six subjects were retested in 2002. In general, poorer fitness in the baseline assessment predicted non-participation in retesting as well as test exclusions and interruptions in retesting. The 6-year changes in the HRF showed a linear trend (P<0.01) according to age group: performance of older groups deteriorated on average more than the performance of younger groups. In most of the tests, gender was statistically significantly (P<0.05) associated with the changes in performance. The mean performance of the women deteriorated in all tests during the follow-up, while the mean performance of the men deteriorated only in the trunk side-bending, 6.1-m walk and 1-km walk tests. It can be concluded that among the subjects who participated in the follow-up testing, older age and being a woman increased deterioration in several components of HRF. Considering the selection of the subjects, the deteriorations identified are very likely underestimations of real fitness changes among this sample.

Back extensor muscle oxygenation and fatigability in healthy subjects and low back pain patients during dynamic back extension exertion

The purpose of this study was to assess if chronic low back pain patients have impaired paraspinal muscle O 2 turnover and endurance capacity as compared to healthy control subjects during dynamic exercise. Middle-aged healthy male subjects ( n = 12, control) and male patients with chronic low back pain ( n = 17, CLBP) participated in the study. L4–L5 level paraspinal muscle fatigue was objectively assessed during earlier validated 90 s dynamic back endurance test (spectral EMG, MPF slope). Also EMG amplitude (EMG amplitude) and initial MPF (MPF initial) were assessed from the initial 5 s of the endurance contraction. Simultaneously near infrared spectroscopy (NIRS) was used for quantitative measurement of local L4–L5 paraspinal muscle O 2 consumption. Subcutaneous tissue thickness (ATT) was measured from the EMG and NIRS recording sites. The results indicated that control and CLBP groups were compatible as regarding anthropometric variables, paraspinal muscle activation levels (EMG amplitude), initial MPF (MPF initial) and ATT. When the ATT was used as a covariate in the ANOVA analysis, CLBP group did not show significantly greater paraspinal muscle fatigability (right MPF slope – 12.2 ± 10.7%/min, left right MPF slope – 12.6 ± 13.3%/min) or O 2 consumption (right NIRS slope – 52.8 ± 79.6 μM/l/s) as compared to healthy controls (right MPF slope – 11.9 ± 7.6%/min, left MPF slope – 12.7 ± 8.6%/min, right NIRS slope – 53.7 ± 95.2 μM/l/s). As a conclusion, these CLBP male patients did not show any impaired rate of paraspinal muscle oxygen consumption or excessive paraspinal muscle fatigability during dynamic exercise as compared with healthy controls. Subcutaneous tissue thickness has a strong influence on the NIRS and EMG amplitude measurements and, if unchecked, it could result in the false interpretation of the results.

EFFECTS OF PELVIC STABILIZATION ON LUMBAR MUSCLE ACTIVITY DURING DYNAMIC EXERCISE

Many commonly utilized lowback exercise devices offer mechanisms to stabilize the pelvis and to isolate the lumbar spine, but the value of these mechanisms remains unclear. The purpose of this study was to examine the effect of pelvic stabilization on the activity of the lumbar and hip extensor muscles during dynamic back extension exercise. Fifteen volunteers in good general health performed dynamic extension exercise in a seated upright position on a lumbar extension machine with and without pelvic stabilization. During exercise, surface electromyographic activity of the lumbar multifidus and biceps femoris was recorded. The activity of the multifidus was 51% greater during the stabilized condition, whereas there was no difference in the activity of the biceps femoris between conditions. This study demonstrates that pelvic stabilization enhances lumbar muscle recruitment during dynamic exercise on machines. Exercise specialists can use these data when designing exercise programs to develop low back strength.

Effects of Pelvic Stabilization on Lumbar Muscle Activity During Dynamic Exercise

Many commonly utilized low-back exercise devices offer mechanisms to stabilize the pelvis and to isolate the lumbar spine, but the value of these mechanisms remains unclear. The purpose of this study was to examine the effect of pelvic stabilization on the activity of the lumbar and hip extensor muscles during dynamic back extension exercise. Fifteen volunteers in good general health performed dynamic extension exercise in a seated upright position on a lumbar extension machine with and without pelvic stabilization. During exercise, surface electromyographic activity of the lumbar multifidus and biceps femoris was recorded. The activity of the multifidus was 51% greater during the stabilized condition, whereas there was no difference in the activity of the biceps femoris between conditions. This study demonstrates that pelvic stabilization enhances lumbar muscle recruitment during dynamic exercise on machines. Exercise specialists can use these data when designing exercise programs to develop low back strength.

Isometric Strength and Dynamic Back Extensor Endurance are Unrelated in Children Ages 6–10 Years: A Pilot Study

This study assessed the correlation between back extensor isometric force and dynamic endurance in 69 children 6-10 years of age. Subjects were positioned prone with legs and hips supported and restrained on two folded 6-in. mats. 42 subjects (20 girls; 22 boys) performed three 5-sec. isometric back extension efforts against a calibrated dynamometer and peak force values were averaged. An additional 27 subjects (9 girls; 18 boys) also performed a dynamic (0 degrees --> 45 degrees flexion-->0 degrees) back extension test at a frequency of 20 per minute, and the number of repetitions was recorded. Both tests were repeated at a 1-wk. interval. Pearson correlations for the endurance, the isometric force test, and test-retest, and between the functional concentric endurance vs isometric force were .55, .79 (both p<.01), and .03, respectively. These tests have moderate to high reliability but they examine different aspects of back muscle fitness. They should not be used interchangeably to assess back extensor muscle fitness. Further investigation must determine whether different dynamic test frequencies and mat heights yield different results.

A health-related fitness and functional performance test battery for middle-aged and older adults: Feasibility and health-related content validity

Malmberg JJ, Miilunpalo SI, Vuori IM, Pasanen ME, Oja P, Haapanen-Niemi NA. A health-related fitness and functional performance test battery for middle-aged and older adults: feasibility and health-related content validity. Arch Phys Med Rehabil 2002;83:666-77. Objective: To evaluate the feasibility and health-related content validity of 6 health-related fitness (HRF) and 3 functional performance (FP) tests among middle-aged and older persons. Design: Cross-sectional methodologic study. Setting: Field laboratories in 3 communities of northeast Finland. Participants: A regionally representative, community-based cohort of 55- to 79-year-old men (n=501) and women (n=632). Interventions: Not applicable. Main Outcome Measures: Health-related test exclusion rates (%) by age groups and odds ratios (ORs) of subjective health outcomes by fitness categories (least 20%, next 40%, most fit 40%). Results: The health-related test exclusion rates increased with age, mainly because of musculoskeletal health limitations among the women and cardiovascular and musculoskeletal health limitations among the men. With the exception of dynamic back extension, 1-leg squat, 1-leg standing balance, and the 1-km walk among the women 75 years and older, 85% or more of the subjects qualified for the HRF tests and 95% or more for the FP tests. Strong and graded associations were found for cardiorespiratory and musculoskeletal fitness and the FP test levels with perceived health and functional ability status among both the men and the women (OR range, 2-31). The motor fitness test level was primarily associated with functional ability status. Conclusions: All the HRF and FP tests showed health-related content validity, and 4 of 6 of the HRF tests and all of the FP tests proved to be safe, with minor health-related test exclusions for middle-aged and older adults. The findings may help to target physical activity intervention toward persons at high risk for declining health and functional ability. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Electromyographic activity of the lumbar extensor muscles: Effect of angle and hand position during Roman Chair Exercise

Objective: To evaluate the effects of angle and hand position during variable-angle Roman chair (VARC) back extension exercise on lumbar paraspinal electromyographic (EMG) activity. Design: Descriptive, repeated measures. Setting: University-based musculoskeletal research laboratory. Participants: Two female and eight male volunteers recruited from a university setting. Intervention and Outcome Measures: Surface integrated EMG activity was recorded from the L3-L4 paraspinal region during 24 10-second repetitions of dynamic back extension exercise, each consisting of a unique VARC angle (six total) and subject hand position (four total). Lumbar paraspinal surface integrated EMG activity measured in millivolts per repetition was used for analysis. Results: Significant lumbar paraspinal EMG activity was evident during each of the 24 repetitions ( p ≤ .05), with a 104% increase in activity noted between the lowest and highest. EMG activity increased progressively among hand positions and as the VARC angle became more horizontal. VARC angle affected EMG activity more than hand position, but the greatest impact on EMG activity was produced by modifying both angle and hand position. Conclusion: Lumbar paraspinal EMG activity can be altered during VARC back extension exercise by changing angle and hand position. Clinicians can use these data to develop progressive resistance exercise programs using the VARC apparatus.

Clinical Trial of Postoperative Dynamic Back Exercises After First Lumbar Discectomy

Ninety-six patients who had undergone first-time discectomy for herniated lumbar intervertebral discs were consecutively randomized to two physical rehabilitation programs: a program of high-intensity, dynamic back extension and abdominal exercises with occurrence of low back pain being the limiting factor or a traditional program of mild, generally mobility-improving exercises within pain limits. Both groups underwent 14 hours of treatment during a 6-week period 5 weeks after surgery. At 26 weeks' follow-up, results indicated that patients who did the high-intensity exercises experienced greater success with regard to the patient disability-index and work capabilities. After 1 year, a trend that favored the use of intensive exercises could be observed. No differences were found in pain or objective measurements. A rehabilitation program of intensive exercises with occurrence of back pain being the limiting factor appears to increase patient behavioral support, resulting in work capacity improvements and patient self-rated disability levels. The results indicate that a 6-wk, 14-hr postoperative rehabilitation program is inadequate if objective postoperative deficit improvements are the desired goal.

Testing of isometric and isokinetic lifting strengths of untrained females in teamwork.

The additivity of strengths for teams of two and three untrained female subjects in eam-work was evaluated in static (isometric) and dynamic (isokinetic) terms. Eight healthy college students were tested under laboratory conditions. Four standard values were used to evaluate isometric strengths: arm, leg, stooped back, and composite measures. The isokinetic strength was tested by means of dynamic lift strength and dynamic back extension. Following individual measurement of the subjects, they were tested in two-member and three-member teams. Two-female teams w«re evaluated in terms of 28 combinations for each of the six measures; the three-female teams were tested in 56 combinations among the subjects. With the exception of isometric arm strength, the actual team strengths were significantly lower then the corresponding sums of the team-members' individual strengths. On average, the isometric back, leg and composite strengths were approximately 83·3% for the two-female teams, and 83·9% for the three-female...

Dynamic Lifting Strengths of Male and Female Teams: A Comparative Study

The objective of this study was to compare dynamic lifting strengths of females and males working in teams of two and three members. The experimental data from two laboratory experiments was used for the purpose of statistical comparison of team strength values for dynamic back extension and dynamic lifting strengths. 15 two-member teams, all male and all female, and 20 three-member teams, all male and all female, participated in the study. Comparison of the team strengths for males and females indicates that on the average, female 2-person strengths account for about 65% and 62% of that of males for dynamic lift and back extension, respectively. For the teams of three people, females are weaker than males by about 28% and 21%, with respect to dynamic lift and back extension strength measures, respectively.

Isometric and isokinetic testing of lifting strength of males in teamwork.

Additivity of static (isometric) and dynamic (isokinetic) strengths for teams of two and three males was evaluated. Six healthy college students participated in the laboratory experiment. The isometric strength evaluations consisted of four standard measures: arm, stooped back, leg, and composite, while the dynamic lift strength and dynamic back extension strength were used in isokinetic strength testing. In addition to individual strengths, the two-man strengths (15 teams for each of the six strengths) and the three-man strengths (20 teams for each of the six strengths) were tested. With the exception of the isometric leg strength for the team of two, and the isometric arm strength for the team of three, the team strengths were significantly lower (P<0·01) than the respective sums of the individual strengths of team members. On the average, the isometric strengths were approximately 94% of the sums of corresponding individual strengths for the team of two males. For the team of three males, the team isometric strengths averaged only 90% of the sum of individual strengths, with the exception of arm strength. The isokinetic strengths for the teams of two and three males accounted only for about 68 and 58% of the respective sums. The above results, indicating that human isometric and isotonic lifting strengths are not additive, suggest that the lifting capability of males in teamwork would be reduced as the number of team members increases.