The influence of rowing-related postures upon respiratory muscle pressure and flow generating capacity.

During the rowing stroke, the respiratory muscles are responsible for postural control, trunk stabilisation, generation/transmission of propulsive forces and ventilation (Bierstacker et al. in Int J Sports Med 7:73-79, 1986; Mahler et al. in Med Sci Sports Exerc 23:186-193, 1991). The challenge of these potentially competing requirements is exacerbated in certain parts of the rowing stroke due to flexed (stroke 'catch') and extended postures (stroke 'finish'). The purpose of this study was to assess the influence of the postural role of the trunk muscles upon pressure and flow generating capacity, by measuring maximal respiratory pressures, flows, and volumes in various seated postures relevant to rowing. Eleven male and five female participants took part in the study. Participants performed two separate testing sessions using two different testing protocols. Participants performed either maximal inspiratory or expiratory mouth pressure manoeuvres (Protocol 1), or maximal flow volume loops (MFVLs) (Protocol 2), whilst maintaining a variety of specified supported or unsupported static rowing-related postures. Starting lung volume was controlled by initiating the test breath in the upright position. Respiratory mouth pressures tended to be lower with recumbency, with a significant decrease in P (Emax) in unsupported recumbent postures (3-9 % compared to upright seated; P = 0.036). There was a significant decrease in function during dynamic manoeuvres, including PIF (5-9 %), FVC (4-7 %) and FEV(1) (4-6 %), in unsupported recumbent postures (p < 0.0125; Bonferroni corrected). Thus, respiratory pressure and flow generating capacity tended to decrease with recumbency; since lung volumes were standardised, this may have been, at least in part, influenced by the postural co-contraction of the trunk muscles.