Tom Tong - Academia.edu (original) (raw)
Papers by Tom Tong
International Journal of Molecular Sciences, 2013
This study investigated the 1-year longitudinal effect of professional training in adolescent run... more This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre-and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT,
Journal of Exercise Science & Fitness, 2012
This study investigated the acute changes in glycemic homeostasis in response to brief, high-inte... more This study investigated the acute changes in glycemic homeostasis in response to brief, high-intensity, intermittent exercise in obese adults. Ten obese adults (age: 25.3 AE 5.1 years; body mass index: 32.0 AE 4.0) volunteered to participate in the study. The time-course changes in blood glucose in response to a 75-g oral glucose tolerance test were examined following: high-intensity intermittent exercise (HIE) of four 30-second all-out cycling efforts interspersed with 4-minute active recovery periods; 24 hours of recovery post-HIE (REC); and no treatment (control, CON). Blood glucose in each trial was measured before, and 30, 60, 90, and 120 minutes after glucose intake (GI). Blood glucose (mmol/L) at 30 minutes post-GI in the HIE (6.9 AE 0.4) trial was significantly lower ( p < 0.05) than the corresponding values of the CON (9.0 AE 0.4) and REC (8.8 AE 0.4) trials. Blood glucose concentration at 120 minutes post-GI in the REC (5.7 AE 0.3) trial was also significantly lower ( p < 0.05) than the corresponding value of the CON (6.9 AE 0.4) trial. When blood glucose values were plotted against corresponding time points, the area under the curve (mmol/L/minute) of the CON (890 AE 43) trial was significantly greater ( p < 0.05) than that of the HIE (834 AE 40) and REC (846 AE 32) trials. The HIE and REC conditions were not significantly different ( p > 0.05). This study demonstrated the improvement in glycemic homeostasis in obese adults immediately after brief, high-intensity, intermittent exercise. These effects were maintained for at least 24 hours postexercise. The findings may be useful in the development of time-efficient lifestyle intervention strategies for improving obesity-related risk factors for diabetes.
International Journal of Molecular Sciences, 2013
This study investigated the 1-year longitudinal effect of professional training in adolescent run... more This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre-and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT,
International Journal of Sports Medicine, 2008
Cardiac troponin release is generally found in adult athletes after continuous-type endurance exe... more Cardiac troponin release is generally found in adult athletes after continuous-type endurance exercises or sport competitions. The purpose of this study was to investigate whether the physical stress experienced by adolescents while playing basketball, an intense, intermittent-type sport, could induce transient elevations of the serum cardiac troponin T (cTnT) and I (cTnI). Serum cTnT and cTnI levels in 10 male adolescent players (age 15.0 +/- 0.7 yr) were assessed immediately before and at 2, 4 and 24 h after a game randomly selected from a preseason basketball-training program. At 4 h following the game, serum cTnT levels in four of the ten subjects were above the cutoff of 0.01 ng . ml (-1) for myocardial injury. Two of these four subjects had values higher than the acute myocardial infarction cutoff of 0.05 ng . ml (-1). In three of the four subjects, the serum cTnI was above the cutoff of 0.06 ng . ml (-1) for myocardial injury. Nevertheless, serum cardiac troponins at 24 h had returned to pre-exercise levels. These findings suggest that the physical stress encountered during intense, intermittent-type sports could cause release of cardiac troponins in some adolescents at low risk for cardiac disease.
International Journal of Sports Medicine, 2009
The purpose of this study was to evaluate the interactive effects of exercise duration and intens... more The purpose of this study was to evaluate the interactive effects of exercise duration and intensity on the elevation of serum cardiac troponin T (cTnT) in trained adolescent athletes following prolonged exercise in a laboratory-based setting. Thirteen male adolescent runners (mean age 14.8+/-1.6 year) performed two 45-min and two 90-min constant-load treadmill runs with intensities set at the running speeds that corresponded to either 80% or 100% ventilatory threshold (Th(vent)): 80%Th(vent)45 min, 80%Th(vent)90 min, 100%Th(vent)45 min and 100%Th(vent)90 min. Serum cTnT was assessed pre and post exercise. In the 100%Th(vent)45 min trial, the post-exercise serum cTnT level [(Median) 0.015 ng x ml(-1); (Range)<0.01-0.375 ng x ml(-1)] was greater than that of the 80%Th(vent)45 min (undetectable cTnT) and 80%Th(vent)90 min (detectable cTnT in two subjects, 0.021 and 0.133 ng x ml(-1)) trials (P<0.01). The serum cTnT level was further increased in the 100%Th(vent)90 min trial [(Median) 0.063 ng x ml(-1); (Range)<0.01-0.417 ng x ml(-1)] when the treadmill run was sustained for an additional 45 min (P<0.05). Similar changes were observed in the cTnT positive rate in subjects. These findings suggest that exercise duration and intensity are essential factors in eliciting cTnT release interactively following an endurance exercise. Nevertheless, exercise intensity compared to duration appears to cause a more pronounced increase in cTnT levels.
Oxidative Medicine and Cellular Longevity, 2012
This study evaluated the impact of professional training on serum oxidant and antioxidant status ... more This study evaluated the impact of professional training on serum oxidant and antioxidant status in adolescent endurance athletes and compared it with that of untrained individuals. Firstly, serum thiobarbituric-acid-reactive substances (TBARSs), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were measured in 67 male runners, cyclists, and untrained adolescents. Seven-day dietary intakes were also assessed. Secondly, for age- and Tanner-stage-matched comparison, 36 out of the 67 subjects (12 for each group) were then selected and investigated. In cyclists, XO, GSH, and CAT were higher as compared with runners and controls. The CAT in runners, but not GSH and XO, was also higher than in controls. TBARS, T-AOC, and SOD did not differ among the study populations. Regarding the inter-individual relationships among serum redox statuses and dietary nutrient intakes, significant correlations were noted in CAT versus carbohydrates, protein, magnesium, and manganese; GSH versus carbohydrates, protein, fat, selenium, zinc, iron, and magnesium; XO versus cholesterol; CAT versus GSH. These findings suggest that the resting blood redox balance in the professional adolescent athletes was well maintained partly by the increase of individual antioxidant in adaptation to chronic exercise.
Scandinavian Journal of Medicine & Science in Sports, 2011
This study examined the response of serum biomarkers of cardiac and skeletal muscle damage at res... more 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 AE 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.
Medicine & Science in Sports & Exercise, 2007
Medicine & Science in Sports & Exercise, 2007
Journal of Exercise Science & Fitness, 2009
Nonalcoholic steatohepatitis (NASH) is hepatic inflammation caused by a buildup of fat in the liv... more 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
Journal of Exercise Science & Fitness, 2010
Post-exercise cardiac biomarker release has been widely reported in adult athlete groups but limi... more 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, < 0.01-1.33 ng·mL −1 ) and NT-pro-BNP (median, range: 132.6, 73.8-370.6 pg·mL −1 ) were elevated (p < 0.05) compared to pre-exercise (median, range: cTnT, < 0.01, < 0.01-0.02 ng·mL −1 ; NT-pro-BNP, 113.8, 39.1-240.6 pg·mL −1 ). There was no significant correlation between delta NT-pro-BNP with peak post-exercise cTnT (r = 0.29, p > 0.05). Further, there was no significant difference in peak postexercise 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. [ J Exerc Sci Fit • Vol 8 • No 2 • 61-66 • 2010]
European Journal of Sport Science, 2012
European Journal of Applied Physiology, 2010
It is well documented that intense exercise precipitates oxidative stress in adults. However, the... more It is well documented that intense exercise precipitates oxidative stress in adults. However, there is lack of related studies concerning oxidant and antioxidant status during early and late recovery periods in adolescent athletes, following endurance exercise in particular. This study investigated aspects of the serum oxidant and antioxidant status of 12 male adolescent (16.2 ± 0.6 years) trained runners during early and late recovery periods after an allout 21-km run. Venous blood samples were taken immediately before, 2 and 4 h following (early recovery period), and 24 h following (late recovery period) the 21-km run.
European Journal of Applied Physiology, 2010
The objective of this study was to determine if prolonged exercise resulted in the appearance of ... more The objective of this study was to determine if prolonged exercise resulted in the appearance of cardiac troponin T (cTnT) in serum and whether this was associated with elevated levels of myocardial oxidative stress. Fortyfive male Sprague-Dawley rats were randomized into four groups and killed before (PRE-EX), immediately (0HR), 2 (2HR) and 24 h (24HR) after a 3-h bout of swimming with 5% body weight attached to their tail. In all animals serum cTnT was assayed using 3rd generation electrochemiluminescence. In homogenized heart tissue myocardial malondialdehyde (MDA), a marker of lipid peroxidation, glutathione (GSH), and a non-enzymatic estimate of total antioxidant capacity (T-AOC) were assessed spectrophotometrically. At PRE-EX cTnT was undetectable in all animals. At 0HR (median, range: 0.055, 0.020-0.100) and 2HR post-exercise (0.036, 0.016-2.110) cTnT was detectable in all animals (P \ 0.05). At 24HR post-exercise cTnT was undetectable in all animals. An elevation in MDA was observed 0HR (mean ± SD: 1.7 ± 0.2 nmol mgpro -1 ) and 2HR (1.6 ± 0.3 nmol mgpro -1 ) post-exercise compared with PRE-EX (1.3 ± 0.2 nmol mgpro -1 ; P \ 0.05). The antioxidant response to this challenge was a significant (P \ 0.05) decrease in GSH 2HR and 24HR post-exercise. Despite this T-AOC did not alter across the trial (P [ 0.05). The results indicated that prolonged and strenuous exercise in rats resulted in an elevation in cTnT, a biomarker of cardiomyocyte damage, in all animals 0HR and 2HR after exercise completion. The time course of cTnT elevation was temporally associated with evidence of increased lipid peroxidation in the rat heart.
European Journal of Applied Physiology, 2003
To identify the reserve of an individual&amp;#39;s tolerance of the sensation of breathle... more To identify the reserve of an individual&amp;#39;s tolerance of the sensation of breathlessness and metabolic stress in maintaining intense intermittent exercise at exhaustion under conditions of normal breathing, the contribution of the effect of modest inspiratory load on these two responses to the change in the exercise sustainability (Ex(sus)) were examined. Seven men repeatedly performed 12 s exercise at 160% maximal aerobic power output followed by passive recovery for 18 s under normal and ventilatory muscle loaded (VML) breathing conditions until exhaustion. In the VML trial, ventilatory muscle work at exhaustion was double that of the normal control. The control Ex(sus) was reduced [mean (SEM)] [31.7 (6.6)%] while the slope of the time course for the rating of the perceived magnitude of breathing effort (RPMBE/Time), which reflected the intensity of breathlessness, was increased [164.8 (32.2)%] from control and the RPMBE at exhaustion was higher than corresponding control value [144.4 (21.8)%]. Moreover, increases in plasma ammonia and uric acid concentrations, which indicated metabolic stress, were increased [168.1 (28.0)% and 251.7 (57.4)%, respectively], with no change in total oxygen uptake from control when the control exercise was repeated with an identical duration of VML exercise. It was found that the reduction in Ex(sus) in the VML trial was correlated to the increase in their sensations of the intensity of breathlessness (RPMBE/Time: r=0.81; RPMBE at exhaustion: r=0.97, P&amp;lt;0.05). The reduction in Ex(sus), however, was not correlated to the increase in metabolite concentrations. These findings implied that there was no substantial reserve of tolerance of the sensation of breathlessness relative to that of metabolic stress in subjects maintaining intense intermittent exercise at exhaustion under normal conditions of breathing.
Applied Physiology, Nutrition, and Metabolism, 2008
The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) duri... more The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) during Yo-Yo intermittent recovery test and on the physiological and perceptual responses to the running test were examined. Thirty men were randomly allocated to 1 of 3 groups. The experimental group underwent a 6 week pressure threshold IM training program by performing 30 inspiratory efforts twice daily, 6 d/week, against a load equivalent to 50% maximal static inspiratory pressure. The placebo group performed the same training procedure but with a minimal inspiratory load. The control group received no training. In post-intervention assessments, IM function was enhanced by >30% in the experimental group. The Ex was improved by 16.3% ± 3.9%, while the rate of increase in intensity of breathlessness (RPB/4i) was reduced by 11.0% ± 6.2%. Further, the whole-body metabolic stress reflected by the accumulations of plasma ammonia, uric acid, and blood lactate during the Yo-Yo test at the same absolute intensity was attenuated. For the control and placebo groups, no significant change in these variables was observed. In comparison with previous observations that the reduced RPB/4i resulting from IM warm-up was the major reason for improved Ex, the reduced RPB/4i resulting from the IM training program was lower despite the greater enhancement of IM function, whereas improvement in Ex was similar. Such findings suggest that although both IM training and warm-up improve the tolerance of intense intermittent exercise, the underlying mechanisms may be different.
Applied Physiology, Nutrition, and Metabolism, 2007
The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered... more The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FW max ) 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 (P 0 ) and maximal rate of P 0 development (MRPD), respectively (p < 0.05). FW max 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 (Á) in parameters in IMW (n = 10), negative correlations were found between ÁP 0 and ÁRPB/min (r 2 = 0.58), ÁMRPD and ÁRPB/min (r 2 = 0.48), ÁRPB/min, and ÁFW max (r 2 = 0.55), but not between Á[La -] b accumulation and ÁFW max . 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.
American Journal of Human Biology, 2011
Objectives: This article examines the effects of brief, intense exercise in comparison with tradi... more Objectives: This article examines the effects of brief, intense exercise in comparison with traditional endurance exercise on both novel and traditional markers of cardiovascular disease (CVD) in youth.
International Journal of Molecular Sciences, 2013
This study investigated the 1-year longitudinal effect of professional training in adolescent run... more This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre-and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT,
Journal of Exercise Science & Fitness, 2012
This study investigated the acute changes in glycemic homeostasis in response to brief, high-inte... more This study investigated the acute changes in glycemic homeostasis in response to brief, high-intensity, intermittent exercise in obese adults. Ten obese adults (age: 25.3 AE 5.1 years; body mass index: 32.0 AE 4.0) volunteered to participate in the study. The time-course changes in blood glucose in response to a 75-g oral glucose tolerance test were examined following: high-intensity intermittent exercise (HIE) of four 30-second all-out cycling efforts interspersed with 4-minute active recovery periods; 24 hours of recovery post-HIE (REC); and no treatment (control, CON). Blood glucose in each trial was measured before, and 30, 60, 90, and 120 minutes after glucose intake (GI). Blood glucose (mmol/L) at 30 minutes post-GI in the HIE (6.9 AE 0.4) trial was significantly lower ( p < 0.05) than the corresponding values of the CON (9.0 AE 0.4) and REC (8.8 AE 0.4) trials. Blood glucose concentration at 120 minutes post-GI in the REC (5.7 AE 0.3) trial was also significantly lower ( p < 0.05) than the corresponding value of the CON (6.9 AE 0.4) trial. When blood glucose values were plotted against corresponding time points, the area under the curve (mmol/L/minute) of the CON (890 AE 43) trial was significantly greater ( p < 0.05) than that of the HIE (834 AE 40) and REC (846 AE 32) trials. The HIE and REC conditions were not significantly different ( p > 0.05). This study demonstrated the improvement in glycemic homeostasis in obese adults immediately after brief, high-intensity, intermittent exercise. These effects were maintained for at least 24 hours postexercise. The findings may be useful in the development of time-efficient lifestyle intervention strategies for improving obesity-related risk factors for diabetes.
International Journal of Molecular Sciences, 2013
This study investigated the 1-year longitudinal effect of professional training in adolescent run... more This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre-and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT,
International Journal of Sports Medicine, 2008
Cardiac troponin release is generally found in adult athletes after continuous-type endurance exe... more Cardiac troponin release is generally found in adult athletes after continuous-type endurance exercises or sport competitions. The purpose of this study was to investigate whether the physical stress experienced by adolescents while playing basketball, an intense, intermittent-type sport, could induce transient elevations of the serum cardiac troponin T (cTnT) and I (cTnI). Serum cTnT and cTnI levels in 10 male adolescent players (age 15.0 +/- 0.7 yr) were assessed immediately before and at 2, 4 and 24 h after a game randomly selected from a preseason basketball-training program. At 4 h following the game, serum cTnT levels in four of the ten subjects were above the cutoff of 0.01 ng . ml (-1) for myocardial injury. Two of these four subjects had values higher than the acute myocardial infarction cutoff of 0.05 ng . ml (-1). In three of the four subjects, the serum cTnI was above the cutoff of 0.06 ng . ml (-1) for myocardial injury. Nevertheless, serum cardiac troponins at 24 h had returned to pre-exercise levels. These findings suggest that the physical stress encountered during intense, intermittent-type sports could cause release of cardiac troponins in some adolescents at low risk for cardiac disease.
International Journal of Sports Medicine, 2009
The purpose of this study was to evaluate the interactive effects of exercise duration and intens... more The purpose of this study was to evaluate the interactive effects of exercise duration and intensity on the elevation of serum cardiac troponin T (cTnT) in trained adolescent athletes following prolonged exercise in a laboratory-based setting. Thirteen male adolescent runners (mean age 14.8+/-1.6 year) performed two 45-min and two 90-min constant-load treadmill runs with intensities set at the running speeds that corresponded to either 80% or 100% ventilatory threshold (Th(vent)): 80%Th(vent)45 min, 80%Th(vent)90 min, 100%Th(vent)45 min and 100%Th(vent)90 min. Serum cTnT was assessed pre and post exercise. In the 100%Th(vent)45 min trial, the post-exercise serum cTnT level [(Median) 0.015 ng x ml(-1); (Range)<0.01-0.375 ng x ml(-1)] was greater than that of the 80%Th(vent)45 min (undetectable cTnT) and 80%Th(vent)90 min (detectable cTnT in two subjects, 0.021 and 0.133 ng x ml(-1)) trials (P<0.01). The serum cTnT level was further increased in the 100%Th(vent)90 min trial [(Median) 0.063 ng x ml(-1); (Range)<0.01-0.417 ng x ml(-1)] when the treadmill run was sustained for an additional 45 min (P<0.05). Similar changes were observed in the cTnT positive rate in subjects. These findings suggest that exercise duration and intensity are essential factors in eliciting cTnT release interactively following an endurance exercise. Nevertheless, exercise intensity compared to duration appears to cause a more pronounced increase in cTnT levels.
Oxidative Medicine and Cellular Longevity, 2012
This study evaluated the impact of professional training on serum oxidant and antioxidant status ... more This study evaluated the impact of professional training on serum oxidant and antioxidant status in adolescent endurance athletes and compared it with that of untrained individuals. Firstly, serum thiobarbituric-acid-reactive substances (TBARSs), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were measured in 67 male runners, cyclists, and untrained adolescents. Seven-day dietary intakes were also assessed. Secondly, for age- and Tanner-stage-matched comparison, 36 out of the 67 subjects (12 for each group) were then selected and investigated. In cyclists, XO, GSH, and CAT were higher as compared with runners and controls. The CAT in runners, but not GSH and XO, was also higher than in controls. TBARS, T-AOC, and SOD did not differ among the study populations. Regarding the inter-individual relationships among serum redox statuses and dietary nutrient intakes, significant correlations were noted in CAT versus carbohydrates, protein, magnesium, and manganese; GSH versus carbohydrates, protein, fat, selenium, zinc, iron, and magnesium; XO versus cholesterol; CAT versus GSH. These findings suggest that the resting blood redox balance in the professional adolescent athletes was well maintained partly by the increase of individual antioxidant in adaptation to chronic exercise.
Scandinavian Journal of Medicine & Science in Sports, 2011
This study examined the response of serum biomarkers of cardiac and skeletal muscle damage at res... more 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 AE 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.
Medicine & Science in Sports & Exercise, 2007
Medicine & Science in Sports & Exercise, 2007
Journal of Exercise Science & Fitness, 2009
Nonalcoholic steatohepatitis (NASH) is hepatic inflammation caused by a buildup of fat in the liv... more 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
Journal of Exercise Science & Fitness, 2010
Post-exercise cardiac biomarker release has been widely reported in adult athlete groups but limi... more 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, < 0.01-1.33 ng·mL −1 ) and NT-pro-BNP (median, range: 132.6, 73.8-370.6 pg·mL −1 ) were elevated (p < 0.05) compared to pre-exercise (median, range: cTnT, < 0.01, < 0.01-0.02 ng·mL −1 ; NT-pro-BNP, 113.8, 39.1-240.6 pg·mL −1 ). There was no significant correlation between delta NT-pro-BNP with peak post-exercise cTnT (r = 0.29, p > 0.05). Further, there was no significant difference in peak postexercise 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. [ J Exerc Sci Fit • Vol 8 • No 2 • 61-66 • 2010]
European Journal of Sport Science, 2012
European Journal of Applied Physiology, 2010
It is well documented that intense exercise precipitates oxidative stress in adults. However, the... more It is well documented that intense exercise precipitates oxidative stress in adults. However, there is lack of related studies concerning oxidant and antioxidant status during early and late recovery periods in adolescent athletes, following endurance exercise in particular. This study investigated aspects of the serum oxidant and antioxidant status of 12 male adolescent (16.2 ± 0.6 years) trained runners during early and late recovery periods after an allout 21-km run. Venous blood samples were taken immediately before, 2 and 4 h following (early recovery period), and 24 h following (late recovery period) the 21-km run.
European Journal of Applied Physiology, 2010
The objective of this study was to determine if prolonged exercise resulted in the appearance of ... more The objective of this study was to determine if prolonged exercise resulted in the appearance of cardiac troponin T (cTnT) in serum and whether this was associated with elevated levels of myocardial oxidative stress. Fortyfive male Sprague-Dawley rats were randomized into four groups and killed before (PRE-EX), immediately (0HR), 2 (2HR) and 24 h (24HR) after a 3-h bout of swimming with 5% body weight attached to their tail. In all animals serum cTnT was assayed using 3rd generation electrochemiluminescence. In homogenized heart tissue myocardial malondialdehyde (MDA), a marker of lipid peroxidation, glutathione (GSH), and a non-enzymatic estimate of total antioxidant capacity (T-AOC) were assessed spectrophotometrically. At PRE-EX cTnT was undetectable in all animals. At 0HR (median, range: 0.055, 0.020-0.100) and 2HR post-exercise (0.036, 0.016-2.110) cTnT was detectable in all animals (P \ 0.05). At 24HR post-exercise cTnT was undetectable in all animals. An elevation in MDA was observed 0HR (mean ± SD: 1.7 ± 0.2 nmol mgpro -1 ) and 2HR (1.6 ± 0.3 nmol mgpro -1 ) post-exercise compared with PRE-EX (1.3 ± 0.2 nmol mgpro -1 ; P \ 0.05). The antioxidant response to this challenge was a significant (P \ 0.05) decrease in GSH 2HR and 24HR post-exercise. Despite this T-AOC did not alter across the trial (P [ 0.05). The results indicated that prolonged and strenuous exercise in rats resulted in an elevation in cTnT, a biomarker of cardiomyocyte damage, in all animals 0HR and 2HR after exercise completion. The time course of cTnT elevation was temporally associated with evidence of increased lipid peroxidation in the rat heart.
European Journal of Applied Physiology, 2003
To identify the reserve of an individual&amp;#39;s tolerance of the sensation of breathle... more To identify the reserve of an individual&amp;#39;s tolerance of the sensation of breathlessness and metabolic stress in maintaining intense intermittent exercise at exhaustion under conditions of normal breathing, the contribution of the effect of modest inspiratory load on these two responses to the change in the exercise sustainability (Ex(sus)) were examined. Seven men repeatedly performed 12 s exercise at 160% maximal aerobic power output followed by passive recovery for 18 s under normal and ventilatory muscle loaded (VML) breathing conditions until exhaustion. In the VML trial, ventilatory muscle work at exhaustion was double that of the normal control. The control Ex(sus) was reduced [mean (SEM)] [31.7 (6.6)%] while the slope of the time course for the rating of the perceived magnitude of breathing effort (RPMBE/Time), which reflected the intensity of breathlessness, was increased [164.8 (32.2)%] from control and the RPMBE at exhaustion was higher than corresponding control value [144.4 (21.8)%]. Moreover, increases in plasma ammonia and uric acid concentrations, which indicated metabolic stress, were increased [168.1 (28.0)% and 251.7 (57.4)%, respectively], with no change in total oxygen uptake from control when the control exercise was repeated with an identical duration of VML exercise. It was found that the reduction in Ex(sus) in the VML trial was correlated to the increase in their sensations of the intensity of breathlessness (RPMBE/Time: r=0.81; RPMBE at exhaustion: r=0.97, P&amp;lt;0.05). The reduction in Ex(sus), however, was not correlated to the increase in metabolite concentrations. These findings implied that there was no substantial reserve of tolerance of the sensation of breathlessness relative to that of metabolic stress in subjects maintaining intense intermittent exercise at exhaustion under normal conditions of breathing.
Applied Physiology, Nutrition, and Metabolism, 2008
The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) duri... more The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) during Yo-Yo intermittent recovery test and on the physiological and perceptual responses to the running test were examined. Thirty men were randomly allocated to 1 of 3 groups. The experimental group underwent a 6 week pressure threshold IM training program by performing 30 inspiratory efforts twice daily, 6 d/week, against a load equivalent to 50% maximal static inspiratory pressure. The placebo group performed the same training procedure but with a minimal inspiratory load. The control group received no training. In post-intervention assessments, IM function was enhanced by >30% in the experimental group. The Ex was improved by 16.3% ± 3.9%, while the rate of increase in intensity of breathlessness (RPB/4i) was reduced by 11.0% ± 6.2%. Further, the whole-body metabolic stress reflected by the accumulations of plasma ammonia, uric acid, and blood lactate during the Yo-Yo test at the same absolute intensity was attenuated. For the control and placebo groups, no significant change in these variables was observed. In comparison with previous observations that the reduced RPB/4i resulting from IM warm-up was the major reason for improved Ex, the reduced RPB/4i resulting from the IM training program was lower despite the greater enhancement of IM function, whereas improvement in Ex was similar. Such findings suggest that although both IM training and warm-up improve the tolerance of intense intermittent exercise, the underlying mechanisms may be different.
Applied Physiology, Nutrition, and Metabolism, 2007
The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered... more The effects of inspiratory muscle (IM) warm-up on IM function and on the maximum distance covered in a subsequent incremental badminton-footwork test (FW max ) 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 (P 0 ) and maximal rate of P 0 development (MRPD), respectively (p < 0.05). FW max 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 (Á) in parameters in IMW (n = 10), negative correlations were found between ÁP 0 and ÁRPB/min (r 2 = 0.58), ÁMRPD and ÁRPB/min (r 2 = 0.48), ÁRPB/min, and ÁFW max (r 2 = 0.55), but not between Á[La -] b accumulation and ÁFW max . 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.
American Journal of Human Biology, 2011
Objectives: This article examines the effects of brief, intense exercise in comparison with tradi... more Objectives: This article examines the effects of brief, intense exercise in comparison with traditional endurance exercise on both novel and traditional markers of cardiovascular disease (CVD) in youth.