No abstract

The immediate post-exercise/physical activity period is critical for sickle cell trait (SCT) carriers and disease (SCD) patients. Indeed, exercise-related blood acidosis known to trigger the cascade: HbS deoxygenation and polymerization, and subsequently red blood cells sickling, aggravates during the initial post-exercise period. This deterioration lies on the conjunction of two facts: First, blood lactate and H+ concentrations continue to increase during several minutes after exercise completion, aggravating blood acidosis. Second, blood lactate concentrations remain elevated and pH altered for 20-45 minutes in case of inactivity after intense exercise, keeping acid/base balance disturbed for a long period post-exercise. Therefore, the risk of complications (including vaso-occlusive crises and even sudden deaths) persists and even worsens several minutes after intensive exercise completion in SCT carriers or SCD patients. Light physical activity following intense exercise (namely active recovery) may, by accelerating lactate removal and acid/base balance restoration, be of paramount importance in that context. Scientific evidences suggest that a light exercise below or at maximum to the first lactate threshold would constitute an appropriate strategy.

In elite oarsmen, the rowing ergometer is a valuable tool for both training and studying rowing performance determinants. However, the energy cost of rowing, often reported as a determinant of performance, has never been described for ergometer rowing. Therefore, this study aimed to characterize the energy cost of ergometer rowing (ECR) in elite oarsmen, its contribution to 2,000 m performance, and its determinants. This study was conducted on 21 elite oarsmen from the French national team. It included an incremental exercise test up to exhaustion and an all-out performance test over 2,000 m, both conducted on a rowing ergometer. Gas exchange analysis was performed to calculate oxygen uptake and substrate utilization rate. Whole blood lactate concentrations during the incremental test were obtained from the earlobe. During the incremental test, ECR displayed a significant linear increase up to a plateau that reached a mean rowing speed of 5.23 ± 0.02 m⋅s–1. The ECR values at 300, 350, and 400 W were positively correlated with performance expressed as the time required to perform the 2,000 m distance on the rowing ergometer. The same ECR values were found to be significantly related to fat oxidation (expressed in percentage of total energy supply) and blood lactate concentrations. This study provides the first description of ECR and of its relationship to exercise intensity on the rowing ergometer in elite oarsmen. ECR appeared to be a factor of performance and interestingly was related to energy supply from fat and blood lactate concentrations.