Frank H. Fu

Resting and post-exercise serum biomarkers of cardiac and skeletal muscle damage in adolescent runners

This study examined the response of serum biomarkers of cardiac and skeletal muscle damage at rest and after a routine workout of 21 km run in 12 male adolescent (16.2±0.6 years) long‐distance runners. Biomarkers of cardiac [troponins (cTnT, cTnI), creatine kinase MB mass (CK‐Mbmass)] and skeletal muscle [creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hydroxybutyrate dehydrogenase (HBD)] damage were assayed at rest, 2, 4 and 24 h post‐exercise. At rest, cTnT and cTnI were not detectable; however, CK, CK‐MBmass, AST, ALT and HBD were above corresponding clinical cut‐off values. Post‐exercise significant elevations above rest were observed for all biomarkers, except ALT, 2 and 4 h following the run, and remained elevated in cTnI, CK, CK‐MBmass, LDH and AST 24 h post‐workout. A significant increase in data points above clinical cut‐off values from rest to post‐exercise was reported for cTnT, cTnI and CK at 2 and 4 h, and in cTnI and CK 24 h post‐exercise. In conclusion, a 21 km run in adolescent runners increased post‐exercise biomarkers of cardiac and skeletal muscle damage.

Effect of specific inspiratory muscle warm-up on intense intermittent run to exhaustion

The effects of inspiratory muscle (IM) warm-up on the maximum dynamic IM function and the maximum repetitions of 20-m shuttle run (Ex) in the Yo-Yo intermittent recovery test were examined. Ten men were recruited to perform identical IM function test and exercise test in three different trials randomly. The control trial was without IM warm-up while the placebo and experimental trials were with IM warm-up by performing two sets of 30 breaths with inspiratory pressure-threshold load equivalent to 15% (IMWP) and 40% (IMW) maximum inspiratory mouth pressure, respectively. In IMW, maximum dynamic IM functions including the maximal inspiratory pressure at zero flow (P0) and maximal rate of P0 development (MRPD) were increased compared with control values (P<0.05). The Ex was also augmented [mean (SD)] [19.5% (12.6)] while the slope of the linear relationship of the increase in rating of perceived breathlessness for every 4th exercise interval (RPB/4i) was reduced (P<0.05). In IMWP, although increase in Ex and reduction in RPB/4i were occurred concomitantly in some subjects, the differences in Ex, RPB/4i and dynamic IM functions between control and IMWP trials were not statistically significant. For the changes (Δ) in parameters in IMW and IMWP (n=20), negative correlations were found between Δ RPB/4i and Δ Ex (r=−0.92), ΔP0 and Δ RPB/4i (r=−0.48), and Δ MRPD and Δ RPB/4i (r=−0.54). Such findings suggested that the specific IM warm-up in IMW may entail reduction in breathlessness sensation, partly attributable to the enhancement of dynamic IM functions, in subsequent exhaustive intermittent run and, in turn, improve the exercise tolerance.

Impact of a 21-km run on cardiac biomarkers in adolescent runners

Post-exercise cardiac biomarker release has been widely reported in adult athlete groups but limited data is available for adolescents. We assessed the impact of a 21-km run on cardiac biomarkers in adolescent athletes and uniquely assessed N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and its potential association with serum cardiac troponin T (cTnT) appearance. NT-pro-BNP and cTnT were measured in 17 male adolescent runners (age, 16.5 ± 1.6 years) before, immediately after and 4 hours after a 21-km run. Post-exercise, both cTnT (median, range: 0.12, p r = 0.29, p > 0.05). Further, there was no significant difference in peak post-exercise cTnT levels (median, range: 0.10, 0.02-1.33 vs. 0.13, 0.02-0.35 ng·mL-1, respectively, p > 0.05) between the subjects with higher delta pre-post NT-pro-BNP values (range, 62.9-186.1 pg·mL-1, n = 8) and the other subjects with lower delta pre-post NT-pro-BNP values (range, 8.3-55.3 pg·mL-1, n = 9). The findings suggest that during recovery from a 21-km run, both serum cTnT and NT-pro-BNP were elevated in adolescent athletes, but no significant relationship existed between increases in both biomarkers. This supports the contention that exercise-induced cTnT and NT-pro-BNP release are largely independently mediated phenomena.

Reduced sensations of intensity of breathlessness enhances maintenance of intense intermittent exercise

To identify the effect of normal breathlessness sensation elicited during intense intermittent exercise at exhaustion on limitation of exercise maintenance (Ex), the contribution of the flow-resistive unloading effect of normoxic helium–oxygen breathing on the breathlessness sensation to the change in the Ex was examined. Seven men repeatedly performed 12-s exercise at 160% maximal aerobic power output followed by passive recovery for 18-s under normal (CON) and unloaded (UL) breathing conditions until exhaustion. In UL, Ex was enhanced [mean (SD) 127.2 (11.8)% CON] concomitantly with reduction in averaged peak inhaled mouth pressure (PPmi) of recorded breathing cycles that reflected approximate true inspiratory muscle force output. At the iso-time point of CON exhaustion, the reduction in PPmi to [75.7(10.2)% CON] in UL was concomitant with the reductions in the rating of perceived breathlessness (RPB) [87.5 (13.1)% CON] and in the slope of time course for RPB (RPB/2-min period) [82.1 (17.2)% CON]. It was also concomitant with increases in ventilation and total oxygen consumption. However, the augmented oxygen consumption did not result in lowering of subjects’ metabolic stress that was indicated by accumulations of blood lactate and plasma ammonia and uric acid. Nevertheless, the reductions in the RPB and RPB/2-min period, which reflected the breathlessness intensity, were correlated to the CON Ex enhancement in UL (RPB r=-0.57, RPB/2-min period r=-0.83; P<0.05). These findings implied that the normal noxious breathlessness sensation elicited during intense intermittent exercise at exhaustion might contribute to the limitation of subjects’ exercise maintenance.

Acute changes in selected serum enzyme and metabolite concentrations in 12- to 14-yr.-old athletes after an all-out 100-m swimming sprint.

The purpose of this study was to investigate the acute effects of an all-out 100-m swimming sprint on changes in serum enzyme and calcium ion concentrations in young (12 to 14 years) male and female swimmers. Changes in serum enzyme concentrations of creatine kinase (CK), lactate dehydrogenase (LDH), glutamic pyruvate transaminase (GPT), glutamic oxaloacetate transaminase (GOT), serum glucose (GL), and calcium ion (Ca2+) concentrations were measured in 23 elite swimmers (13 boys and 10 girls) before and after a 100-m freestyle all-out sprint. Analysis showed (1) there were significant sex differences in serum CK concentration at baseline (Pretest); (2) significant sex differences in serum CK and LDH concentrations after the 100-m spring; (3) no significant differences in Ca2+ concentration after the 100-m spring; and (4) significant increase in Serum GOT and blood glucose concentrations after the 100-m sprint, suggesting chat these might both be useful indicators of anaerobic exercise stress in young swimmers.

CHRONIC AND ACUTE INSPIRATORY MUSCLE LOADING AUGMENT THE EFFECT OF A 6-WEEK INTERVAL PROGRAM ON TOLERANCE OF HIGH-INTENSITY INTERMITTENT BOUTS OF RUNNING

Tong, TK, Fu, FH, Eston, R, Chung, P-K, Quach, B, and Lu, K. Chronic and acute inspiratory muscle loading augment the effect of a 6-week interval program on tolerance of high-intensity intermittent bouts of running. J Strength Cond Res 24(11): 3041-3048, 2010-This study examined the hypothesis that chronic (training) and acute (warm-up) loaded ventilatory activities applied to the inspiratory muscles (IM) in an integrated manner would augment the training volume of an interval running program. This in turn would result in additional improvement in the maximum performance of the Yo-Yo intermittent recovery test in comparison with interval training alone. Eighteen male nonprofessional athletes were allocated to either an inspiratory muscle loading (IML) group or control group. Both groups participated in a 6-week interval running program consisting of 3-4 workouts (1-3 sets of various repetitions of selected distance [100-2,400 m] per workout) per week. For the IML group, 4-week IM training (30 inspiratory efforts at 50% maximal static inspiratory pressure [P0] per set, 2 sets·d−1, 6 d·wk−1) was applied before the interval program. Specific IM warm-up (2 sets of 30 inspiratory efforts at 40% P0) was performed before each workout of the program. For the control group, neither IML was applied. In comparison with the control group, the interval training volume as indicated by the repeatability of running bouts at high intensity was approximately 27% greater in the IML group. Greater increase in the maximum performance of the Yo-Yo test (control: 16.9 ± 5.5%; IML: 30.7 ± 4.7% baseline value) was also observed after training. The enhanced exercise performance was partly attributable to the greater reductions in the sensation of breathlessness and whole-body metabolic stress during the Yo-Yo test. These findings show that the combination of chronic and acute IML into a high-intensity interval running program is a beneficial training strategy for enhancing the tolerance to high-intensity intermittent bouts of running.

Effects of 12 Weeks of Exercise on Hepatic TNF-α and PPARα in an Animal Model of High-Fat Diet-Induced Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is hepatic inflammation caused by a buildup of fat in the liver. This study was designed to examine whether the NASH-associated increase in hepatic TNF-α mRNA expression and serum TNF-α, and decrease in hepatic PPARα mRNA expression in rats secondary to 12-week consumption of a high-fat diet would be attenuated with concurrent exercise. A total of 28 male Sprague-Dawley strain rats were randomly assigned into four groups: standard diet without (C, n = 6) and with (E, n = 7) concurrent exercise; and high-fat diet without (H, n = 8) and with (HE, n = 7) concurrent exercise. The mean daily energy intake during the intervention period resulting from the standard and high-fat diets was approximately 82 kcal and 95 kcal, respectively. Swimming exercise was carried out in the E and HE groups for 12 weeks. The initial swimming duration of 30 minutes was progressively increased by 10 min·d −1 to 90 minutes by the end of the fourth week, which then remained unchanged. NASH revealed by histological activity index, which occurred in the H but not the C group, was alleviated in the HE group. Moreover, the upregulation of hepatic TNF-α mRNA expression and serum TNF-α, and downregulation of hepatic PPARα mRNA expression, which were shown in the H group, were attenuated in the HE group. Such findings suggest that long-term exercise carried out concurrently with consumption of a high-fat diet could alleviate high-fat diet-induced NASH. These may be partly attributable to the attenuation of hepatic TNF-α overexpression and the upregulation of hepatic PPARα mRNA expression.

Accomplishments and Compromises in Prediction Research for World Records and Best Performances in Track and Field and Swimming

The conductors of this study reviewed prediction research and studied the accomplishments and compromises in predicting world records and best performances in track and field and swimming. The results of the study showed that prediction research only promises to describe the historical trends in track and field and swimming performances, to study the limits of human body based on current data, to examine factors that affect humans running, jumping, throwing, and swimming, and to understand the characteristics of human beings. Prediction research cannot accurately predict new world records and future best performances. In the future, prediction research should become an integrated research field consisting of different specialty areas. Researchers need to develop a better model in which random variables could be separated out as independent variables in order to reflect the complex interaction effects and to understand the nature, characteristics, and limitations of humans using world record/best performance data.

High-sensitivity cardiac troponin T release after a single bout of high-intensity interval exercise in experienced marathon runners

Objective The purpose of this study was to investigate the effects of a single bout of high-intensity interval exercise (HIIE) on high-sensitivity cardiac troponin T (hs-cTnT) release and to explore the potential influencing factors. Methods Twenty-one experienced marathon runners completed HIIE on treadmill. Each bout of HIIE included a hard run (15.8 ± 1.3 km·h−1) at 90% vVO2max for 2 min followed by an easy run (8.8 ± 0.7 km·h−1) at 50% vVO2max for 2 min performed 23 times within 92 min. Heart rate (HR) was recorded every 2 min during HIIE. The hs-cTnT level was measured before (pre), immediately after (0 h), and at 4 and 24 h after exercise. Results The hs-cTnT level was elevated at 0 h, peaked at 4 h, and had not returned to the baseline value at 24 h after exercise. The response of hs-cTnT at 4 h was positively related to exercise HR. Subjects with a greater increase in hs-cTnT level had a higher exercise HR under fixed exercise intensity. Conclusion HIIE at 90% vVO2max interspersed with 50% vVO2max for recovery can elicit hs-cTnT elevation. HR is a good predictor of exercise-induced cardiac troponin (cTn) release under fixed exercise intensity. Further study should consider to correct for HR when constructing impact factors contributing to exercise-induced cTn release.