Efficiency and effectiveness of stoop and squat lifting at different frequencies.

The study investigated the effects of frequency (10 and 20 lifts/min) and technique (squat and stoop) of repetitive lifting of a barbell (19 kg) on the relationship between mean power output (Pm) and energy cost in 9 male power-lifters. Oxygen uptake (VO2) was measured directly and continuously and power output was deduced from film analysis using an inverse dynamic analysis. Power output and VO2 were significantly greater for squat than for stoop lifting at the same frequency. The mechanical efficiency (ME), defined as Pm divided by the energy equivalence of VO2, increased from 12% at rate 10 to 18.5% at rate 20, but there was no significant difference between the two techniques. The effectiveness (EF), defined as the productive external power output (only work done on the barbell) divided by the energy equivalence of VO2, was significantly higher for the stoop lift than for the squat lift. EF is judged as a more useful measure than ME for characterizing the relative energy cost of a lifting task.

[1]  J. Durnin,et al.  Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 Years , 1974, British Journal of Nutrition.

[2]  Richard B. Chase,et al.  A Work Physiology Study of the Relative Effects of Pace and Weight in a Carton Handling Task , 1969 .

[3]  B. A. Wilson,et al.  Exercise efficiency: validity of base-line subtractions. , 1980, Journal of applied physiology: respiratory, environmental and exercise physiology.

[4]  S H Snook,et al.  Maximum frequency of lift acceptable to male industrial workers. , 1968, American Industrial Hygiene Association journal.

[5]  A. R. Lind,et al.  Comparison of metabolic and ventilatory responses of men to various lifting tasks and bicycle ergometry. , 1978, Journal of applied physiology: respiratory, environmental and exercise physiology.

[6]  A. R. Lind,et al.  Metabolic, cardiovascular, and respiratory factors in the development of fatigue in lifting tasks. , 1978, Journal of applied physiology: respiratory, environmental and exercise physiology.

[7]  K. Jørgensen,et al.  Physiological problems in repetitive lifting with special reference to tolerance limits to the maximum lifting frequency. , 1974, Ergonomics.

[8]  S J Legg,et al.  A psychophysical study of the effects of load and frequency upon selection of workload in repetitive lifting. , 1986, Ergonomics.

[9]  J R Brown,et al.  Lifting as an industrial hazard. , 1973, American Industrial Hygiene Association journal.

[10]  S H Snook,et al.  The Effects of Age and Physique on Continuous-Work Capacity , 1971, Human factors.

[11]  N. Nie.  SPSS-X User's Guide , 1983 .

[12]  G. W. Snedecor.  Statistical Methods , 1964 .

[13]  Miller Jc,et al.  Physiological analysis of repetitive lifting. , 1977 .

[14]  S Kumar,et al.  The physiological cost of three different methods of lifting in sagittal and lateral planes. , 1984, Ergonomics.

[15]  S J Legg,et al.  A physiological study of the repetitive lifting capabilities of healthy young males. , 1984, Ergonomics.

[16]  A Garg,et al.  Effects of lifting frequency and technique on physical fatigue with special reference to psychophysical methodology and metabolic rate. , 1979, American Industrial Hygiene Association journal.