Breath control during manual free-style lifting of a maximally tolerated load

Abstract

Clear evidence links voluntary breath control, intra-abdominal pressure and lumbar stability. However, little is known regarding optimal breath control during manual materials handling. No studies have examined natural breath control while lifting a maximal load. Fourteen healthy subjects lifted a loaded crate from the floor to a table while respiratory flow data were collected. The loads lifted began at 10% of body weight and increased up to 50% (if tolerated) by 5% increments. Data from the minimum, moderate and maximum loads were analysed. Uniform and consistent breath holding during lifting of a maximally tolerated load did not occur. Across all three loads, frequency of inspiration was highest immediately prior to lift-off and significantly higher inspired volume occurred at lift-off of the load compared with preparation for lifting. Holding the breath does not appear to be related to lifting of a maximally tolerated load from floor to table. STATEMENT OF RELEVANCE: The findings demonstrate that consistent patterns of naturally occurring breath control during lifting of a maximal load can be identified and do not include uniform breath holding. The findings may assist in creating models for optimal breath control, which will minimise risk of injury during manual material handling tasks.

Fig. 1

Mean inspired volume for the MIN, MOD, and MAX loads. For MIN, volume was higher at lift-off and +50% compared to placement, as well as at +25% compared to −25%, −50%, −75%, and placement. For MOD, volume was higher at −25% compared to −75%, as well as at lift-off, +25% and +50% compared to all pre-lift and placement. For MAX, volume was higher at lift-off and +25% compared to pre-lift, +50%, +75% and placement, as well as at −25%, +50%, and +75% compared to −50% and −75%. In addition, at −75%, lift-off, +25%, +75%, and placement volume was higher when comparing MAX with MIN. Further, at lift-off and +75% volume was higher when comparing MAX with MOD. All differences (p<0.05)

Fig 2

Frequency of occurrence of inspiration (A), expiration (B), or breath holding (C) for the MIN, MOD, and MAX loads. Significant differences were found at: Start: MIN exp>MIN insp. −75%: MIN exp>MIN bh and insp; MOD exp<MIN or MAX exp; MAX exp>MAX bh or insp. −50%: all loads bh<insp and exp. −25%: all loads insp>bh and exp Lift-off: MIN insp>MIN bh and exp; MIN insp>MOD or MAX insp. +50%: MIN exp>MIN bh and insp; MOD exp>MOD bh and insp; MAX exp<MIN or MOD exp. +75%: MIN exp>MIN bh and insp; MOD exp>MOD bh and insp; MAX insp<MAX bh and exp; MAX bh>MIN or MOD bh. +25% and Placement: none. Legend: Insp = inspiration; bh = breath holding; exp = expiration.