Assessment of Exercise Stroke Volume and Its Prediction From Oxygen Pulse in Paralympic Athletes With Locomotor Impairments: Cardiac Long-Term Adaptations Are Possible

The determinants of cardiac output (CO) during exercise, i.e., stroke volume (SV) and heart rate (HR), could differ in Paralympic athletes (PAthl) with spinal cord injury (SCI) with respect to PAthl with locomotor impairments caused by different health conditions (HCs). The purposes of the present study were the comparisons of two groups of PAthl, one with SCI and the other with either amputation (AMP) or post poliomyelitis syndrome (PM), assessing the (1) peak cardiorespiratory responses and determinants (SV and HR) of CO during maximal and submaximal arm cranking exercise (ACE), respectively; (2) correlations between peak oxygen uptake (VO(2peak)) and the highest SV obtained during submaximal exercise; and (3) correlations between oxygen pulse (O(2) pulse, ratio between VO(2) and HR) and both SV and O(2) arterio-venous difference [(a-v)O(2)diff]. Each athlete (19 PAthl with SCI, 9 with AMP, and 5 with PM) completed a continuous incremental cardiopulmonary ACE test to volitional fatigue to assess peak responses. In a different session, CO was indirectly measured through carbon dioxide (CO(2)) rebreathing method at sub-maximal exercise intensities approximating 30, 50, and 70% of the VO(2peak). There were no significant differences between the PAthl groups in age, anthropometry, and VO(2peak). However, peak HR was significantly lower, and peak O(2) pulse was significantly higher in PAthl with AMP/PM compared to those with SCI. During sub-maximal exercise, PAthl with AMP/PM displayed significantly higher SV values (154.8 ± 17.60 ml) than PAthl with SCI (117.1 ± 24.66 ml). SV correlated significantly with VO(2peak) in both PAthl with SCI (R(2) = 0.796) and AMP/PM (R(2) = 0.824). O(2) pulse correlated significantly with SV in both PAthl with SCI (R(2) = 0.888) and AMP/PM (R(2) = 0.932) and in the overall sample (R(2) = 0.896). No significant correlations were observed between O(2) pulse and (a-v)O(2)diff. It was concluded that in PAthl with different HCs: (1) significant differences, as a consequence of the different HC, exist in the determinants of CO at maximal and submaximal ACE; (2) SV is a significant determinant of VO(2peak), suggesting cardiac adaptations possible also in PAthl with SCI; and (3) SV can be predicted from O(2) pulse measurements during submaximal exercise in both groups of PAthl.