Cardiac perturbations after high-intensity exercise are attenuated in middle-aged compared with young endurance athletes: diminished stress or depleted stimuli?

Strenuous exercise elicits transient functional and biochemical cardiac imbalances. Yet, the extent to which these responses are altered owing to aging is unclear. Accordingly, echocardiograph-derived left ventricular (LV) and right ventricular (RV) global longitudinal strain (GLS) and high-sensitivity cardiac troponin I (hs-cTnI) were assessed before (pre) and after (post) a 60-min high-intensity cycling race intervention (CRIT60) in 11 young (18-30yr) and 11 middle-aged (40-65yr) highly trained male cyclists, matched for cardiorespiratory fitness. LV and RV GLS were measured at rest and during a semirecumbent exercise challenge performed at the same intensity (young: 93 +/- 10; middle-aged: 85 +/- 11W, P = 0.60) pre- and post-CRIT60. Augmentation (change from rest-to-exercise challenge) of LV GLS (pre: -2.97 +/- 0.65; post: -0.82 +/- 0.48%, P = 0.02) and RV GLS (pre: -2.08 +/- 1.28; post: 3.08 +/- 2.02%, P = 0.01) was attenuated and completely abolished, in the young following CRIT 60 , while augmentation of LV GLS (pre: -3.21 +/- 0.41; post: 3.99 +/- 0.55%, P = 0.22) and RV GLS (pre: 3.47 +/- 1.44; post: 1.26 +/- 1.00%, P = 0.27) was preserved in middle-aged following CRIT60. While serum hs-cTnl concentration increased following CRIT60 in the young (pre: 7.3 +/- 1.6; post: 17.7 +/- 1.6 ng/L, P < 0.01) and middle-aged (pre: 4.5 +/- 0.6; post: 10.7 +/- 2.0 ng/L, P < 0.01), serum hs-cTnI concentration increased to a greater extent in the young than in the middle-aged following CRIT60 (P < 0.01). These findings suggest that functional and biochemical cardiac perturbations induced by high-intensity exercise are attenuated in middle-aged relative to young individuals. Further study is warranted to determine whether acute exercise-induced cardiac perturbations after the adaptive myocardial remodeling response. NEW & NOTEWORTHY High-intensity endurance exercise elicits acute cardiac imbalances that may be an important stimulus for adaptive cardiac remodeling. This study highlights that following a bout of high-intensity exercise that is typical of routine day-to-day cycling training, exercise-induced autonomic, biochemical, and functional cardiac imbalances are attenuated in middle-aged relative to young well-trained cyclists. These findings suggest that aging may alter exercise-induced stress stimulus response that initiates cardiac remodeling in athlete's heart.