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

Marco Bernardi,Donatella Dante,Federico Schena,Emanuele Guerra,Angelo Rodio,Yagesh Bhambhani,Vincenzo Castellano,Ilaria Peluso

doi:10.3389/fphys.2019.01451

Abstract

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 (VO2peak) and the highest SV obtained during submaximal exercise; and (3) correlations between oxygen pulse (O2 pulse, ratio between VO2 and HR) and both SV and O2 arterio-venous difference [(a-v)O2diff]. 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 (CO2) rebreathing method at sub-maximal exercise intensities approximating 30, 50, and 70% of the VO2peak. There were no significant differences between the PAthl groups in age, anthropometry, and VO2peak. However, peak HR was significantly lower, and peak O2 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 VO2peak in both PAthl with SCI (R2 = 0.796) and AMP/PM (R2 = 0.824). O2 pulse correlated significantly with SV in both PAthl with SCI (R2 = 0.888) and AMP/PM (R2 = 0.932) and in the overall sample (R2 = 0.896). No significant correlations were observed between O2 pulse and (a-v)O2diff. 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 VO2peak, suggesting cardiac adaptations possible also in PAthl with SCI; and (3) SV can be predicted from O2 pulse measurements during submaximal exercise in both groups of PAthl.

Highlights

IntroductionAerobic fitness levels have been well documented in recreational (Abel et al, 2008) and Paralympic Athletes (PAthl) with locomotor impairments (Baumgart et al, 2018) competing in summer (Bernardi et al, 2010) and winter sports (Bernardi et al, 2012), those with spinal cord injury (SCI; Bernard et al, 2000; Bhambhani, 2002; van der Woude et al, 2002)
The highest stroke volume (SV) found at submaximal intensities in Paralympic Athletes (PAthl) with spinal cord injury (SCI) was significantly lower than that measured in PAthl with AMP/poliomyelitis syndrome (PM)
The corresponding HR values were significantly lower in PAthl with AMP/PM than those with SCI

Summary

Introduction

Aerobic fitness levels have been well documented in recreational (Abel et al, 2008) and Paralympic Athletes (PAthl) with locomotor impairments (Baumgart et al, 2018) competing in summer (Bernardi et al, 2010) and winter sports (Bernardi et al, 2012), those with spinal cord injury (SCI; Bernard et al, 2000; Bhambhani, 2002; van der Woude et al, 2002). Crosssectional evidence indicates that trained individuals with SCI (tetraplegia and paraplegia) have significantly higher peak oxygen uptake (VO2peak) values compared to their sedentary counterparts (Flandrois et al, 1986; Hopman et al, 1996; Huonker et al, 1998; Schumacher et al, 2009) and that the changes in aerobic fitness in PAthl with locomotor impairments are determined by the practiced sport (Bhambhani, 2002; Bernardi et al, 2010, 2012; Baumgart et al, 2018). Central factors, which enhance systemic oxygen availability, include significant increases in blood volume and hemoglobin concentration in endurance trained athletes with paraplegia (Schumacher et al, 2009). Peripheral factors that contribute to a greater increase in maximal O2 extraction [i.e., (a-v)O2diff] include greater capillary and mitochondrial density, as well as enhanced activity of enzymes in the aerobic metabolic pathways (Bhambhani, 2002)

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