Influence of lifting technique on perceptual and cardiovascular responses to submaximal repetitive lifting

Abstract

Oxygen consumption ($\dot V$O₂), heart rate, ventilation and central rating of perceived exertion (RPE) in repetitive lifting while executing squat and stoop techniques were investigated in ten male forestry workers. In all five mass/frequency combinations studied,$\dot V$O₂ was significantly higher for the squat than for the stoop technique. No differences were found in RPE between the techniques. The$\dot V$O₂ and RPE recordings were also related to those obtained during maximal repetitive lifting (same lifting technique) and maximal treadmill running. The$\dot V$O₂ expressed as a percentage of that obtained during maximal repetitive lifting with the same lifting technique was defined as relative aerobic intensity (%$\dot V$O_{2max, lifting}). The %$\dot V$O_{2max, lifting} was not significantly different between the techniques except for the lowest mass lifted (1 kg). This study therefore would support the hypothesis that RPE is more closely related to %$\dot V$O_{2max, lifting} than to absolute aerobic intensity. Related to maximal treadmill running, it was demonstrated for both lifting techniques that relative RPE (percentage of the RPE during maximal running) was more accurate than relative$\dot V$O₂ (percentage of maximal$\dot V$O₂ during maximal running) for determining the %$\dot V$O_{2max, lifting} in repetitive lifting. The study showed that the higher$\dot V$O₂ during squat. lifting compared to stoop lifting was caused by the$\dot V$O₂ expended in lifting and lowering the body rather than the$\dot V$O₂ expended lifting and lowering the external mass. It was concluded that the stoop technique was not superior to the squat technique in terms of central RPE. Based on %$\dot V$O_{2max, lifting}, there may be a rationale for choosing the stoop technique during repetitive lifting with light masses, but not with heavy masses.