The effect of back belt use on isometric lifting force and fatigue of the lumbar paraspinal muscles.

STUDY DESIGN: A repeated measures multivariate design to assess the effect of back belts on isometric lifting force and lumbar paraspinal muscle fatigue. OBJECTIVE: To determine the efficacy of lumbar back belts in minimizing a loss in isometric force production and fatigue of lumbar paraspinal muscles. SUMMARY OF BACKGROUND DATA: Increased prevalence of back belts in industry and lack of scientific evidence supporting them suggested additional research was needed. There has been no conclusive research to substantiate manufacturer claims that use of belts reduces fatigue of lumbar paraspinals. METHODS: Twenty-four subjects, 13 men and 11 women, were tested twice: once with and once without a belt. All subjects performed a dynamic lifting task at a rate of 10 lifts per minute for 20 minutes. Surface electromyograms from the lumbar paraspinals and isometric force measurements were recorded during a static maximal isometric lift at 0, 10, and 20 minutes. Load during the dynamic task was determined as 20% of initial maximum isometric force. Electromyographic data were used to detect changes in median power spectral frequencies. Muscular fatigue was indicated by a reduction in median power spectral frequency values or a decrease in isometric force-generating capacity. RESULTS: Multivariate and univariate analyses suggest that there is no effect on lumbar paraspinal muscle fatigue or isometric lifting force production as a result of back belt use. CONCLUSIONS: These findings do not support the use of back belts for the purpose of minimizing either lumbar paraspinal muscle fatigue or a loss in isometric lifting force production.

Oxygen consumption, heart rate, and rating of perceived exertion in young adult women during backward walking at different speeds.

Backward walking has gained popularity as an adjunct to treatment for patients undergoing rehabilitation for patellofemoral pain syndrome and anterior cruciate ligament injuries. Researchers have suggested that backward walking decreases the compressive forces at the patellofemoral joint while also preventing overstretching of the anterior cruciate ligament. Prior to this study, precise prescription of backward walking speeds for women was not possible. The purpose of this study was to determine the relationship between heart rate, oxygen consumption, and backward walking speeds. Twenty-five healthy, adult female volunteers participated in this study. Subjects were tested at speeds of 0.96, 1.20, 1.43, 1.67, and 1.91 m/sec. Subjects also performed a graded exercise stress test. Analysis revealed curvilinear relationships between oxygen consumption and speed as well as between heart rate and speed. With these results, clinicians may now prescribe specific speeds of backward walking for women to elicit a desired cardiopulmonary response.

Investigation of the validity and reliability of four objective techniques for measuring forward shoulder posture.

Clinicians often rely on visual inspection and descriptive terms to documents a patient's forward shoulder posture. The purpose of this study was to assess the validity and intrarater reliability of four objective techniques to measure forward shoulder posture. Subjects were 25 males and 24 females. Subjects had a lateral cervical spine radiograph taken, from which the horizontal distance from the C7 spinous process to the anterior tip of the left anterior acromion process was measured. Subjects then proceeded twice through a random order of four measurements: the Baylor square, the double square, the Sahrmann technique, and scapular position. These results were then used to determine the intrarater reliability of each technique. Multiple regression analyses were performed on each measure's mean scores to determine both the correlation with and the predictive value for the radiographic measurement. The intraclass correlation coefficients for intrarater reliability ranged from .89 to .91. The correlation coefficients ranged from -.33 to .77, and the coefficients of determination ranged from .10 to .59 (N = 49). The researchers demonstrated clinical reliability for each technique; however, validity compared with the radiographic measurement could not be established. These techniques may have clinical value in objectively measuring change in a patient's shoulder posture as a result of a treatment program. Before any of these measures could be universally recommended in clinical practice, future research is necessary to establish interrater reliability and assess each technique's ability to detect postural changes over time.

The cardiopulmonary cost of backward walking at selected speeds.

Backward walking has been advocated as a method of maintaining cardiovascular conditioning in patients undergoing knee rehabilitation because it may decrease patellofemoral joint compressive forces. The primary purpose of this study was to determine the relationship between the rate of oxygen consumption (VO2) and backward walking speed. Twenty-five healthy males, aged 18-35 years, participated in this study. The rate of oxygen consumption and heart rate were measured at the backward walking speeds of 0.89, 1.12, 1.34, 1.56, and 1.79 m/sec (2.0, 2.5, 3.0, 3.5, and 4.0 miles/hour, respectively). Analysis revealed a direct, curvilinear relationship between VO2 and backward walking speed. This research provides information that can be used to prescribe a backward walking rehabilitation program which may be appropriate to maintain aerobic fitness levels during rehabilitation of patients with patellofemoral pain syndrome.