Study design: This was a repeated measures study examining 11 asymptomatic subjects while performing dynamic lifting using various postures, loads, and breath control methods.
Objectives: To examine the effects of breath control on magnitude and timing of intra-abdominal pressure during dynamic lifting.
Summary of background data: Intra-abdominal pressure has been shown to increase consistently during static and dynamic lifting tasks. The relationship between breath control and intra-abdominal pressure during lifting is not clear.
Methods: Eleven healthy subjects were tested using lifting trials consisting of two levels of posture and load and four levels of breath control (natural breathing, inhalation-hold, exhalation-hold, inhalation-exhalation). Intra-abdominal pressure was measured using a microtip pressure transducer placed within the stomach through the nose. Timing of intra-abdominal pressure was determined relative to lift-off of the weights. Repeated measures analysis of variance was used to determine the effect of breath control, posture, and load on intra-abdominal pressure magnitude and timing.
Results: There was a significant effect of breath control (P < 0.018) and load (P < 0.002), but not of posture (P < 0.434), on intra-abdominal pressure magnitude. The inhalation-hold form of breath control produced significantly greater peak intra-abdominal pressure than all other forms of breath control (P < 0.000 for all comparisons). No other comparisons among levels of breath were significantly different. No significant main effects of breath control were found relative to intra-abdominal pressure timing.
Conclusions: Breath control is a significant factor in the generation of intra-abdominal pressure magnitude during lifting tasks. The effects of respiration should be controlled in studies analyzing intra-abdominal pressure during lifting.