Ventilation while swimming is generally constrained by the medium (water) and the obligatory timing associated with arm mechanics. Attempts at describing ventilation have been similarly constrained and therefore little published data exists on operating lung volumes and pulmonary function while swimming at maximal efforts. This is in contrast to the considerable data available for cycling and running.
PURPOSE: To compare swimming and cycling exercise modes on ventilatory variables.
METHODS: Ten trained, competitive men swimmers (age = 24.4 ± 1.91yrs) were asked to perform two incremental exercise tests to volitional exhaustion on separate days, one on a cycle ergometer and a second while swimming in a flume. Tidal volume (VT), peak tidal flow inspired (PTi) and expired (PTe), time to inspire (Ti) and expire (Te), total tidal time (Tt), duty cycle (Ti/TT), and ventilatory capacity (Vcap) were assessed repetitively in both conditions via flow-volume loops. Maximum aerobic capacity (VO2peak) and ventilation (VE) were measured via open flow calorimetry. All variables were recorded over the final minute of each incremental exercise test. Paired t-tests were used to compare the exercise modes, with the level of significance set at 0.05.
RESULTS: In the final minute of the incremental test to exhaustion, swimming resulted in a smaller PTi (4.74 ± 0.29 vs. 5.66 ± 0.29L·s1; p<0.05), but a greater PTe (7.00 ± 0.20 vs. 6.03 ± 0.38L·s1; p<0.05) than for cycling. Ti (0.76 ± 0.05 vs. 0.63 ± 0.38s; p<0.05), Tt (1.48 ± 0.09 vs. 1.28 ± 0.08s; p<0.05), and Ti/TT (56.7 ± 1.1 vs. 49.4 ± 0.7%; p<0.05) were greater for swimming than for cycling. Despite no difference in Te (0.58 ± 0.10 vs. 0.65 ± 0.04s; p=0.13), VO2peak (3.61 ± 0.21 vs. 3.60 ± 0.14 L·min1, p = 0.95) or Vcap (189.1 ± 63.0 vs. 165.9 ± 61.3L·s1; p=0.07) between exercise modes, VE was smaller in swimming versus cycling (102.9 ± 5.8 vs. 129.0 ± 7.8 L·s1; p<0.05).
CONCLUSIONS: Swimming appears to require changes in ventilatory strategies during maximal efforts as compared to similar exercise performed on a cycle ergometer despite similar metabolic demands. Whether or not this is due to postural differences, hydrostatic influences or the obligatory ventilatory entrainment remains unclear.