Cardiospecificity of the 3rd generation cardiac troponin T assay during and after a 216 km ultra-endurance marathon run in Death Valley.

BACKGROUND: The reasons for the appearance of cardiacspecific troponin (cTnT) after strenuous exercise are unclear. The aim of the present study was to evaluate the cardiospecificity of the 3(rd) generation cardiac cTnT assay during and after an ultra-endurance race of 216 km at extreme environmental conditions in Death Valley. STUDY DESIGN AND METHODS: We measured serially cTnT, creatine kinase (CK), activity and mass of the isoenzyme MB of CK (CK-MB(act) and CK-MB(mass)), and myoglobin in 10 well-trained athletes before, repeatedly during and after the race. RESULTS: Six of 10 participants finished the race within a preset time of 60 hours. Postrace values of biochemical markers CK, CK-MB(act), CKMB(mass), and myoglobin were significantly increased compared to baseline (p<0.05). CK-MB(act) increased from (median (25(th)/ 75(th)percentile) 12 (10/13) U/L to 72 (32/110) U/L, CK-MB(mass) from 3.9 (2.9/5.6) U/L to 65 (18/80) U/L and CK increased from median 136 (98/ 228) U/L to 3,570 (985/6,884) U/L respectively. Pre-race myoglobin was 27 (22/31) microg/l compared to 530 (178/657) microg/l after the run. One runner developed significant exercise-induced rhabdomyolysis with spontaneous recovery. cTnT values remained below the 99(th) percentile reference limit in all athletes including the runner who developed significant rhabdomyolysis (peak CK 27,951 U/L). CONCLUSIONS: Strenuous endurance exercise, even under extreme environmental conditions, does not result in structural myocardial damage in well-trained ultra-endurance athletes. We found no crossreactivity between cTnT and CK, neither in exercise-induced skeletal muscle trauma nor after rhabdomyolysis underscoring the excellent analytical performance of 3(rd) generation cTnT assay.

How anaerobic is the Wingate Anaerobic Test for humans?

The Wingate Anaerobic Test (WAnT) is generally used to evaluate anaerobic cycling performance, but knowledge of the metabolic profile of WAnT is limited. Therefore the energetics of WAnT was analysed with respect to working efficiency and performance. A group of 11 male subjects [mean (SD), age 21.6 (3.8) years, height 178.6 (6.6) cm, body mass 82.2 (12.1) kg] performed a maximal incremental exercise test and a WAnT. Lactic and alactic anaerobic energy outputs were calculated from net lactate production and the fast component of the kinetics of post-exercise oxygen uptake. Aerobic metabolism was determined from oxygen uptake during exercise. The WAnT mean power of 683 (96.0) W resulted from a total energy output above the value at rest of 128.1 (23.2) kJ x 30 s(-1) [mean metabolic power=4.3 (0.8) kW] corresponding to a working efficiency of 16.2 (1.6)%. The WAnT working efficiency was lower (P < 0.01) than the corresponding value of 24.1 (1.7)% at 362 (41) W at the end of an incremental exercise test. During WAnT the fractions of the energy from aerobic, anaerobic alactic and lactic acid metabolism were 18.6 (2.5)%, 31.1 (4.6)%, and 50.3 (5.1)%, respectively. Energy from metabolism of anaerobic lactic acid explained 83% and 81% of the variance of WAnT peak and mean power, respectively. The results indicate firstly that WAnT requires the use of more anaerobically derived energy than previously estimated, secondly that anaerobic metabolism is dominated by glycolysis, thirdly that WAnT mechanical efficiency is lower than that found in aerobic exercise tests, and fourthly that the latter finding partly explains discrepancies between previously published and the present data about the metabolic profile of WAnT.

Dependence of the maximal lactate steady state on the motor pattern of exercise.

BACKGROUND: Blood lactate concentration (BLC) can be used to monitor relative exercise intensity. The highest BLC representing an equilibrium between lactate production and elimination is termed maximal lactate steady state (MLSS). MLSS is used to discriminate qualitatively between continuous exercise, which is limited by stored energy, from other types of exercise terminated because of disturbance of cellular homoeostasis. AIM: To investigate the hypothesis that MLSS intraindividually depends on the mode of exercise. METHODS: Six junior male rowers (16.5 (1.4) years, 181.7 (3.1) cm, 69.8 (3.3) kg) performed incremental and constant load tests on rowing and cycle ergometers. Measurements included BLC, sampled from the hyperaemic ear flap, heart rate, and oxygen uptake. MLSS was defined as the highest BLC that increased by no more than 1.0 mmol/l during the final 20 minutes of constant workload. RESULTS: In all subjects, MLSS was lower (p < or = 0.05) during rowing (2.7 (0.6) mmol/l) than during cycling (4.5 (1.0) mmol/l). No differences between rowing and cycling were found with respect to MLSS heart rate (169.2 (9.3) v 172.3 (6.7) beats/min), MLSS workload (178.7 (29.8) v 205.0 (20.7) W), MLSS intensity expressed as a percentage (63.3 (6.6)% v 68.6 (3.8)%) of peak workload (280.8 (15.9) v 299.2 (28.4) W) or percentage (76.4 (3.4)% v 75.1 (3.0)%) of peak oxygen uptake (60.4 (3.4) v 57.2 (8.6) ml/kg/min). CONCLUSIONS: In rowing and cycling, the MLSS but not MLSS workload and MLSS intensity intraindividually depends on the motor pattern of exercise. MLSS seems to decrease with increasing mass of the primarily engaged muscle. This indicates that task specific levels of MLSS occur at distinct levels of power output per unit of primarily engaged muscle mass.

Maximal lactate-steady-state independent of performance.

PURPOSE: The maximal lactate steady state (MLSS) corresponds to the highest workload that can be maintained over time without a continual blood lactate accumulation. MLSS and MLSS intensity have been speculated to depend on performance. Experimental proof of this hypothesis is missing. METHODS: 33 male subjects (age: 23.7 +/- 5.5 yr, height: 181.2 +/- 5.3 cm, body mass: 73.4 +/- 6.4 kg) performed an exhausting incremental load test to measure peak workload and three to six 30-min constant load tests on a cycle ergometer to determine MLSS. RESULTS: MLSS (4.9 +/- 1.4 mmol x L(-1)) was independent of MLSS workload (3.4 +/- 0.6 W x kg(-1)) and peak workload (4.8 +/- 0.6 W x kg(-1)). MLSS intensity (71.1 +/- 6.7%) did not correlate with peak workload or MLSS (P > 0.05). A positive correlation was found between peak workload and MLSS workload (r = 0.82, P < 0.001). CONCLUSIONS: MLSS and MLSS intensity are independent of performance but subjects with higher maximum performance have higher MLSS workloads. The combination of various fitness related effects on both, the production and the disappearance of lactate during exercise, may explain that different MLSS workloads coincide with similar levels of MLSS and MLSS intensity.