Exercise Training Increases Serum Cardiac Troponin T Independent of Left Ventricular Mass.

The purpose of this study was to determine whether exercise training mediated cardiac troponin T (cTnT) and whether this was associated with increases in left ventricular mass (LVM). Fifty-four sedentary obese women were randomised to high-intensity interval training (HIIT, repeated 4-min cycling at 90% V̇O2max interspersed with 3-min rest), work-equivalent continuous aerobic training (CAT, continuous cycling at 60% V̇O2max) or a control group (CON). Resting serum cTnT was assessed using a high-sensitivity assay before and after 12 weeks of training. LVM was determined from 2D echocardiography at the same timepoints. Both HIIT and CAT induced a similar elevation (median 3.07 to 3.76 ng.l-1, p<0.05) in resting cTnT compared with pre-training and the CON (3.49 to 3.45 ng.l-1, p>0.05). LVM index in HIIT increased (62.2±7.8 to 73.1±14.1 g.m-2, p<0.05), but not in CAT (66.1±9.7 to 67.6±9.6 g.m-2, p>0.05) and CON (67.9±9.5 to 70.2±9.1 g.m-2, p>0.05). Training-induced changes in resting cTnT did not correlate with changes in LVM index (r=-0.025, p=0.857). These findings suggest that twelve weeks of either HIIT or CAT increased resting cTnT, but the effects were independent of any changes in LVM in sedentary obese women.

Reproducibility of cardiac biomarkers response to prolonged treadmill exercise.

We examined the reproducibility of alterations in cardiac biomarkers after two identical bouts of prolonged exercise in young athletes. Serum high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were assessed before and after exercise. Significant rises in median hs-cTnT and NT-proBNP occurred in both trials. While the absolute changes in hs-cTnT were smaller after trial 2, the pattern of change was similar and the delta scores were significantly related. However, the change in NT-proBNP was not correlated between trials. The hs-cTnT release demonstrates some consistency after exercise although the blunted hc-cTnT response requires further study.

Renal function parameters during early and late recovery periods following an all-out 21-km run in trained adolescent runners.

BACKGROUND: This study investigated the changes in biomarkers of renal function and the corresponding estimated glomerular filtration rate (eGFR) in 10 male adolescent (16.2±0.6 years) trained runners during early and late recovery periods after an all-out 21-km run. METHODS: Venous blood samples were taken immediately before, and at 2-h, 4-h, and 24-h following the 21-km run. Samples were analyzed for hemoglobin (Hb) and hematocrit (Hct), and serum urea (U), creatinine (Cr), creatine kinase (CK) and lactate dehydrogenase (LDH). U/Cr ratio, eGFR, and plasma volume change (%ΔPV) were calculated based on the associated measured variables. RESULTS: At 2-h and 4-h, there were increases (26%-146%) in U, Cr, U/Cr, CK, and LDH, and decreases (8%-13%) in Hb and Hct, as compared with the corresponding pre-exercise values. The calculated %ΔPV increased by 17% while the eGFR decreased 20% from the corresponding pre-exercise value, respectively. At 24-h, the changes of the blood variables and renal function parameters observed at early recovery period were sustained. CONCLUSIONS: Taken together, the findings of this study suggest that mild decline in renal function occurred during the early recovery period following the 21-km run. The decline in renal function did not return to normal during the later recovery period.

Impact of high-intensity interval and moderate-intensity continuous exercise on heart rate variability and cardiac troponin.

BACKGROUND: It remains uncertain whether exercise modality (high-intensity interval [HIE]; moderate-intensity continuous [MCE]) mediates exercise-induced changes in markers of pro-arrhythmogenic state and/or cardiac damage. This study examines heart rate variability (HRV) and cardiac troponin T (cTnT) kinetic responses to HIE and MCE. METHODS: Fourteen sedentary, overweight/obese females completed two trials including HIE (2-min running at 90% V̇O2max followed by 2-min running at 50% V̇O2max, repeated for 60 min) and MCE (70% V̇O2max steady-state running for 60 min) in a randomized, counterbalanced fashion. Supine HRV was evaluated as root mean square of successive differences (RMSSD), normalized low-frequency (LF) and high-frequency (HF) spectral power, as well as the LF/HF ratio before (PRE), immediately (0 HR), 3 (3 HR) and 24 (24 HR) hours after exercise. Serum cTnT was assessed using a high-sensitivity assay at the same time-points and the values were corrected for plasma volume changes. RESULTS: Exercise temporarily altered all HRV indices (i.e. RMSSD and HF decreased; LF and LF/HF ratio increased at 0 HR, all P<0.05) but a rebound increase of RMSSD was observed at 24 HR, and the kinetic responses of HRV were similar between exercise modalities. The cTnT was significantly elevated (P<0.05) after exercise at 3 HR (by 688%) and 24 HR (by 374%) with no between-modality differences. There was no significant correlation between delta change in cTnT and HRV metrics. CONCLUSIONS: Exercise modality (workload-equivalent HIE vs. MCE) did not mediate exercise-induced alteration in autonomic activity and cTnT elevation, and it seems these are largely separate exercise-induced phenomena.

Myokine/Adipokine Response to "Aerobic" Exercise: Is It Just a Matter of Exercise Load?

PURPOSE: Exercise health benefits are partly mediated by exertional changes in several myokines/adipokines. This study aimed to compare the acute response of some of these biomarkers to aerobic exercise performed at the intensity corresponding to the maximum fat oxidation rate (FATmax) or the "anaerobic" threshold (AT). METHODS: Following a cross-over, counterbalanced design, 14 healthy untrained men (23 ± 1 years) performed a 45-min exercise bout at their FATmax or AT intensity (been previously determined through incremental exercise tests). The concentration of interleukin (IL)-15, follistatin, myostatin, fibroblast-growth factor (FGF)-21, irisin, resistin, and omentin was measured at baseline and 0, 1, 3, 24, 48, and 72 h post-exercise. RESULTS: AT exercise was performed at a higher intensity (85 ± 8 vs. 52 ± 14% of maximal oxygen uptake [VO2 max], p < 0.001) and induced a higher energy expenditure (p < 0.001) than FATmax, whereas a greater fat oxidation was observed in the latter (p < 0.001). A higher peak response of FGF-21 (+90%, p < 0.01) and follistatin (+49%, p < 0.05) was found after AT-exercise, as well as a trend toward a higher peak level of omentin (+13%, p = 0.071) and a greater decrease in resistin (-16%, p = 0.073). CONCLUSION: Increasing exercise load (from FATmax to AT) results in a higher response of FGF-21, follistatin and omentin to aerobic exercise, with the subsequent potential cardiometabolic benefits. No effects were, however, observed on the remainder of biomarkers. Future research should address if manipulating other exercise variables (e.g., type, frequency) can promote a higher myokine/adipokine response.

Myokine Response to High-Intensity Interval vs. Resistance Exercise: An Individual Approach.

Purpose: This study aimed to compare the response to acute exercise of several myokines/hormones involved in metabolic function between two types of training sessions that are growing in popularity for their purported cardiometabolic benefits, high-intensity interval (HIIT) and resistance training (RT). Methods: Seventeen healthy, non-athletic men (23 ± 3 years) participated in this cross-over study. They randomly performed a HIIT [with short (HIIT1) or long (HIIT2) intervals] or a RT session. The concentration of fibroblast-growth factor (FGF) 21, follistatin, ghrelin, interleukin-15, irisin, myostatin, and peptide YY was measured at baseline and 0, 1, 3, 24, 48, and 72 h post-exercise. An individual approach was adopted to determine the rate of responsiveness to each specific cytokine and training mode. Results: A significant condition (session type) by time interaction (p = 0.004) effect was observed for FGF21, with RT eliciting a greater area under the curve (AUC) concentration than HIIT1 (p = 0.02). The AUC for follistatin was significantly greater after HIIT2 compared with RT (p = 0.02). Individual responsiveness to all session types ranged between 19 and 93% depending on the cytokine. However, most subjects (71-100%) responded positively for all cytokines (except for irisin, with only 53% of responders) after 1+ session type. Conclusion: Except for FGF21, our results show no overall differences in the myokine response to HIIT or RT. A considerable individual variability was observed, with some subjects responding to some but not other training session types. Notwithstanding, most responded to at least one training session. Thus, it is mostly the individual response of each subject rather than general recommendations on type of training session (i.e., RT vs. HIIT or HIIT subtypes) that must be taken into consideration for maximizing cardiometabolic benefits in the context of personalized exercise prescription.

Autonomic function responses to training: Correlation with body composition changes.

AIM: The causal relation between autonomic function and adiposity is an unresolved issue. Thus, we studied whether resting heart rate variability (HRV) changes could be used to predict changes in body composition after 16 weeks of individualized exercise training. METHODS: A total of 117 sedentary overweight/obese adults volunteered to join an intervention group (IN, n=82) or a control group (CON, n=35). The intervention group trained for 30-40 min three times a week with an intensity of 85-100% of individual ventilatory threshold (Thvent). At baseline and after a 16-week training period, resting HRV variables, body composition and peak oxygen uptake (VO2peak) were assessed. RESULTS: Compared with CON, exercise training significantly improved HRV and body composition and increased VO2peak (P<0.05). Significant correlations were observed between changes of HRV variables and body composition indices and VO2peak (P<0.05). Greater individual changes in HRV in response to exercise training were observed for those with greater total and central fat loss. CONCLUSION: Individual aerobic-based exercise training was for improving autonomic function and resting HRV responses to aerobic training is a potential indicator for adaptations to exercise training.

The effect of baduanjin on promoting the physical fitness and health of adults.

The purpose of study was to assess the efficacy of a 16-week Baduanjin qigong training intervention in promoting physical fitness and health for adults. An experimental design was adopted, and subjects were assigned randomly into an experimental group (n = 55) and a control group (n = 55). In the intervention group comprised of adults, there were no significant variations in blood glucose, blood lipid, blood pressure, heart rate variability, and vital capacity indices. The body weight and body mass index (BMI) dropped in the intervention group. Compared with the control group, the skinfold thicknesses decreased at lower corner of scapula, triceps brachii, and abdomen, with a statistical significance (P < 0.001; P = 0.005; P = 0.003). By comparing the physical fitness indices, it was found that the increase of the results of sit-and-reach test in the intervention group had statistical significance (P = 0.001). In conclusion, it was found by our trial that Baduanjin exercise could significantly improve the physical flexibility and subcutaneous adipose accumulation in the healthy adults.

The kinetics of highly sensitive cardiac troponin T release after prolonged treadmill exercise in adolescent and adult athletes.

The nature and kinetics of postexercise cardiac troponin (cTn) appearance is poorly described and understood in most athlete populations. We compared the kinetics of high-sensitivity cTn T (hs-cTnT) after endurance running in training-matched adolescents and adults. Thirteen male adolescent (mean age: 14.1 ± 1.1 yr) and 13 male adult (24.0 ± 3.6 yr) runners performed a 90-min constant-load treadmill run at 95% of ventilatory threshold. Serum hs-cTnT levels were assessed preexercise, immediately postexercise, and at 1, 2, 3, 4, 5, 6, and 24 h postexercise. Serum NH(2)-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels were recorded preexercise and 3, 6, and 24 h postexercise. Left ventricular function was assessed preexercise, immediately postexercise, and 6 h postexercise. Peak hs-cTnT occurred at 3-4 h postexercise in all subjects, but was substantially higher (P < 0.05) in adolescents [median (range): 211.0 (11.2-794.5) ng/l] compared with adults [median (range): 19.1 (9.7-305.6) ng/l]. Peak hs-cTnT was followed by a rapid decrease in both groups, although adolescent data had not returned to baseline at 24 h. Substantial interindividual variability was noted in peak hs-cTnT, especially in the adolescents. NT-pro-BNP was significantly elevated postexercise in both adults and adolescents and remained above baseline at 24 h in both groups. In both groups, left ventricular ejection fraction and the ratio of early-to-atrial peak Doppler flow velocities were significantly decreased immediately postexercise. Peak hs-cTnT was not related to changes in ejection fraction, ratio of early-to-atrial peak Doppler flow velocities, or NT-pro-BNP. The present data suggest that postexercise hs-cTnT elevation 1) occurred in all runners, 2) peaked 3-4 h postexercise, and 3) the peak hs-cTnT concentration after prolonged exercise was higher in adolescents than adults.

Specific inspiratory muscle warm-up enhances badminton footwork performance.

The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FWmax) were examined. Ten male badminton players were recruited to perform identical tests in three different trials in a random order. The control trial did not involve an IM warm-up, whereas the placebo and experimental trials did involve an IM warm-up consisting of two sets of 30-breath manoeuvres with an inspiratory pressure-threshold load equivalent to 15% (PLA) and 40% (IMW) maximum inspiratory mouth pressure, respectively. In the IMW trial, IM function was improved with 7.8%+/-4.0% and 6.9%+/-3.5% increases from control found in maximal inspiratory pressure at zero flow (P0) and maximal rate of P0 development (MRPD), respectively (p<0.05). FWmax was enhanced 6.8%+/-3.7%, whereas the slope of the linear relationship of the increase in the rating of perceived breathlessness for every minute (RPB/min) was reduced (p<0.05). Reduction in blood lactate ([La-]b) accumulation was observed when the test duration was identical to that of the control trial (P<0.05). In the PLA trial, no parameter was changed from control. For the changes (Delta) in parameters in IMW (n=10), negative correlations were found between DeltaP0 and DeltaRPB/min (r2=0.58), DeltaMRPD and DeltaRPB/min (r2=0.48), DeltaRPB/min, and DeltaFWmax (r2=0.55), but not between Delta[La-]b accumulation and DeltaFWmax. Such findings suggest that the IM-specific warm-up improved footwork performance in the subsequent maximum incremental badminton-footwork test. The improved footwork was partly attributable to the reduced breathless sensation resulting from the enhanced IM function, whereas the contribution of the concomitant reduction in [La-]b accumulation was relatively minor.