The impact of exercise modality and menstrual cycle phase on circulating cardiac troponin T

Objectives: It is unclear whether exercise modality (moderate-intensity continuous [MCE]; high-intensity interval [HIE]) and menstrual cycle phase (follicular [FP]; luteal [LP]), individually or in combination, mediate the commonly observed exercise-induced elevation in cardiac troponin T (cTnT). This study examines cTnT responses to MCE and HIE during both the FP and LP. Design: Randomised crossover study. Methods: Seventeen healthy, eumenorrheic women completed four trials including MCE (60% VO2max steady-state cycling until 300 kJ) and work-equivalent HIE (repeated 4-min cycling at 90% VO2max interspersed with 3-min rest) during both the FP and LP. The FP and LP were verified based on ovarian hormones. Serum cTnT was assessed using a high-sensitivity assay before, immediately after, and 1 (1 HR), 3 (3 H R) and 4 (4HR) hours after exercise. cTnT values were corrected for plasma volume changes. Results: cTnT was significantly elevated (p <0.05) post-exercise in both MCE (at 3HR and 4HR) and HIE (at 1 HR, 3HR and 4HR). No statistically significant difference (p > 0.05) in peak post-exercise cTnT, which mostly occurred at 3HR, was seen among the four trials (median [range], ngl(-1): 5.2 [1.7-18.1] after MCE during FP; 4.8 [1.7-24.9] after MCE during LP, 8.2 [3.9-24.8] after HIE during FP and 6.9 [1.7-23.1] after HIE during LP). Conclusions: A single 300 kJ bout of both MCE or HIE resulted in a significant post-exercise increase in cTnT, with no differences in peak cTnT response between menstrual cycle phases or between exercise modes, but the cTnT elevation occurs slightly earlier after HIE. (C) 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.