Metabolic and cardiorespiratory responses to continuous box lifting and lowering in nonimpaired subjects

Safety issues in functional capacity evaluation: findings from a trial of a new approach for evaluating clients with chronic back pain

Although safety is recognized as a critical issue in functional capacity evaluations (FCEs), it has rarely been investigated. This paper reports on the findings of a study which examined safety aspects of a new approach to FCE. Fourteen rehabilitation clients with chronic back pain participated in the study. Aspects examined included the pre-FCE screening procedures, the monitoring of performance and safety during the FCE, and the end of FCE measures and follow-up procedures. Support was found for the screening procedures of the approach, particularly blood pressure measurement, and for the combined approach to monitoring of the person's performance from biomechanical, physiological and psychophysical perspectives. Issues for FCE safety in general are identified and discussed, including the importance of screening procedures to determine readiness for FCEs and the issue of load handling in FCEs, especially in relation to clients with chronic back pain.

Metabolic and cardiorespiratory responses to continuous box lifting and lowering in nonimpaired subjects

STUDY DESIGN

A within-subject experimental design.

OBJECTIVES

To compare the magnitude of metabolic and cardiorespiratory changes produced during box lifting and lowering among combinations of lift technique (leg lift and leg-torso lift) and lift weight (10.8 and 15.4 kg).

BACKGROUND

Continuous box lifting and lowering can be used as an exercise in a low-back rehabilitation program. Awareness of the possible cardiovascular stress of this activity is important to the clinician because some patients may have existing cardiovascular pathologies or possess unknown risk factors for cardiovascular disease.

METHODS AND MEASURES

A group of 17 nonimpaired men 26 +/- 8 years of age (mean +/- SD) performed the 4 experimental trials on different days in a counterbalanced order determined by a Latin Square design. Lifting and lowering was performed for 6 continuous minutes at a rate of 12 cycles per minute. Physiologic variables were oxygen uptake, minute ventilation, heart rate, systolic blood pressure, diastolic blood pressure, metabolic equivalent, and rate-pressure product.

RESULTS

There were stepwise increases in the values for oxygen uptake, minute ventilation, heart rate, metabolic equivalent, and rate-pressure product from the leg-torso lift to the leg lift and from 10.8 to 15.4 kg of weight within each lift technique (with the exception that minute ventilation and heart rate did not differ between the leg-torso lift at 15.4 kg and the leg lift at 10.8 kg). For the 4 lifts, values (mean +/- SD) varied from 20.3 +/- 5.4 to 28.8 +/- 5.8 mL x kg x min(-1) for oxygen uptake, 42.2 +/- 11.1 to 66.4 +/- 15.2 L x min(-2) for minute ventilation,129 +/- 20.6 to 156 +/- 16.5 beats x min(-1) for heart rate, 5.8 +/- 1.6 to 8.2 +/- 1.6 for metabolic equivalent, and 197 +/- 49.4 to 245 +/- 41.2 for rate-pressure product (x10(-2)).

CONCLUSION

The leg lift with the 15.4-kg weight produced the greatest physiologic stress. Because of the magnitude of the increase in the variables measured for all 4 types of lifts, clinicians should closely monitor patients' response to this type of exercise.

Relationship between lifting capacity and anthropometric measures

STUDY DESIGN

Prospective analysis of relationship between lifting capacity and multiple anthropometric variables.

OBJECTIVES

To determine the relationship between lifting capacity and anthropometric variables and to model this relationship quantitatively.

BACKGROUND

Low-back injuries commonly occur in individuals who perform lifting tasks. Objective data are needed to determine preinjury lifting capacity that, in turn, might be used to guide decisions during rehabilitation of these injuries.

METHODS AND MEASURES

We recorded age and sex and measured the following variables for 35 men and 23 women between the ages of 22 and 40: height, weight, percentage of body fat, torso height, pelvic width, pelvic girth, arm length, thigh girth, and calf girth. Variables were selected for the study on the basis of theoretical modeling or previous research regarding the relationship between study variables and lifting capacity. Subjects also were tested to determine their maximum lifting capacity by using a lordotic lumbar spine lifting technique.

RESULTS

Stepwise regression analysis indicated that the combination of sex, age, thigh girth, pelvic girth, and percentage body fat was significantly related to maximum lift capacity (multiple R2 = 0.76). The mean absolute difference (+/- SD) between lifted amount predicted by the regression model and the actual amount lifted was 118.6 +/- 86 N (26 +/- 19.3 lb), which corresponded to an average absolute error of 16% (SD = 14%) of the actual weight lifted.

CONCLUSION

The results may be useful in estimating 1 aspect of preinjury lifting capacity. Similar studies are needed to model the requirements of frequency of lift, duration of lifting efforts, variety of hand-object coupling, and combined lifting and reaching.