Student academic performance in non-lecture physiology topics following the abrupt change from traditional on-site teaching to online teaching during COVID-19 pandemic

BACKGROUND

During the COVID-19 pandemic, pre-clerkship medical education, including all physiology classes, was obliged to change to online teaching due to limitations of on-site (face-to-face) classes. However, the effectiveness of online teaching in non-lecture physiology topics during the COVID-19 pandemic has not been thoroughly investigated.

METHOD

We conducted a prospective study to evaluate the students' academic achievement and opinions on online teaching during the COVID-19 academic year. Academic achievement of 312 students in the COVID-19 year was compared with that of 299 students in the pre-COVID-19 year. Student opinions regarding social interactions and the preferred learning method were also collected.

RESULTS

We found that student academic achievement in the non-lecture physiology topics, assessed by summative scores, was 4.80±0.92 percent higher in the pre-COVID-19 year than in the COVID-19 year (P < 0.01, Cohen's d = 0.42). Students rated that online classes tended to reduce their interactions with peers and teachers; however, students preferred online learning over traditional on-site learning.

CONCLUSIONS

This study pointed out that students' academic performance related to the physiology topics taught by online non-lecture methods during the COVID-19 pandemic was lower than their performance when the topics were taught by the traditional (on-site) methods, although students reported that they preferred the online teaching. Hence, we suggest that medical teachers should deliberately plan and utilise a variety of tools and techniques when developing online non-lecture classes to preserve the interactivity of the classes, which might overcome this gap in students' academic performance.

Impact of irregular sleep pattern, and sleep quality on glycaemic parameters and endothelial function in adolescents and young adults with type 1 diabetes

This study investigated the impact of comprehensive sleep patterns on glycaemic parameters and endothelial function in adolescents and young adults with type 1 diabetes (T1D). Thirty subjects with type 1 diabetes (aged 13-25) without chronic complications participated. For 1 week, glucose levels were monitored by real-time continuous glucose monitoring (CGM) and sleep was simultaneously assessed by actigraphy. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Flow-mediated dilatation (FMD) measured endothelial function at the brachial artery. Insulin sensitivity was determined by calculated estimated glucose disposal rate (eGDR). Glycaemic control was assessed using haemoglobin A1C (HbA1C) levels. To address potential confounding by metabolic syndrome on the FMD results, three affected subjects were excluded from FMD correlation analyses. Participants with PSQI scores >5 had a lower %FMD compared with those with scores ≤5 (4.6 ± 3.7% vs. 7.6 ± 3.0%, p = 0.03). Multivariate analysis indicated that lower sleep efficiency and higher sleep duration variability were associated with higher HbA1C levels (β = -0.076, 95%CI [-0.145, -0.008], p = 0.029; β = 0.012, 95%CI [0.001, 0.023], p = 0.033). Irregular sleep timing and lower sleep efficiency were related to decreased insulin sensitivity (sleep midpoint irregularity β = -1.581, 95%CI [-2.661, -0.502], p = 0.004, and sleep efficiency β = 0.147, 95%CI [0.060, 0.235], p = 0.001). No significant associations were found between glycaemic parameters and FMD. Our study demonstrated that sleep irregularity in type 1 diabetes was associated with glycaemic control and insulin resistance, while poor subjective sleep quality was linked to endothelial dysfunction. Promoting healthy sleep habits, including consistent sleep timing could benefit metabolic and cardiovascular health in type 1 diabetes.

Acute effect of various dosages of sugar ingestion on vascular function in offspring of hypertensive and normotensive parents

OBJECTIVES

We aimed to study vascular function in healthy men with a parental history of hypertension compared to those without. Acute effect of various dosages of sugar ingestion on vascular function was also investigated in both groups.

METHODS

Thirty-two healthy men were recruited and divided into two groups, offspring of hypertensive parents (OHT) and offspring of normotensive parents (ONT). Participants were orally given 15, 30, and 60 g of sucrose solution compared to water. Peak forearm blood flow (FBF), forearm vascular resistance (FVR), pulse wave velocity (PWV), and oxidative stress markers were measured at baseline and after sucrose intake at 30, 60, 90, and 120 min.

RESULTS

At baseline, peak FBF was significantly lower (22.40 ± 1.18 vs. 25.24 ± 0.63 ml × dl -1  × min -1 , P  < 0.001), FVR was significantly higher (3.73 ± 0.42 vs. 3.30 ± 0.26 mmHg × ml -1  × dl × min, P  = 0.002), and PWV was significantly faster (6.31 ± 0.59 vs. 5.78 ± 0.61 m/s, P  = 0.017) in OHT than ONT. After each sucrose intake, peak FBF significantly declined and was lowest at 30 min in both groups. The reduction in peak FBF was seen in all doses of sucrose and the higher dose of sucrose intervened, the longer reduction in peak FBF observed.

CONCLUSIONS

Vascular function was attenuated in healthy men with a family history of hypertension and became worse after sucrose ingestion even at the low dose. Our findings suggest that the ones, especially those with a parental history of hypertension, should reduce sugar consumption as low as possible.

Asynchronous online lecture may not be an effective method in teaching cardiovascular physiology during the COVID-19 pandemic

BACKGROUND

Asynchronous online lecture has become a common teaching method in medical education, especially during the COVID-19 pandemic. However, the effectiveness and students' attitudes towards this method under this special circumstance have not been exclusively studied. Hence, we aimed to evaluate these aspects of cardiovascular physiology teaching in an undergraduate medical curriculum.

METHODS

We analysed and compared the academic achievement and attitudes of 613 medical students on cardiovascular physiology between pre-COVID-19 and COVID-19 years in which different teaching methods were implemented. In addition, we also explored the importance of teaching methods and teachers by subgroup analysis to evaluate whether they influenced the academic achievement and attitudes of students.

RESULTS

Overall students' academic achievement was significantly higher when lectures were taught by the traditional method than by the asynchronous online method. Moreover, subgroup analysis revealed that teachers were also a factor influencing students' academic achievement. Although most students had positive attitudes towards asynchronous online lectures, overall satisfaction was slightly higher when all lectures were taught by the traditional method than by the asynchronous online method.

CONCLUSIONS

Asynchronous online lectures might not be an effective teaching method especially during the abrupt change in education. Under the 'new normal' medical education, not only teaching methods but also teachers are the essential keys to the success in academic achievement and attitudes of undergraduate medical students.

Two-dimensional integration approach to teaching cardiovascular physiology: effectiveness and students' perspectives

BACKGROUND

Pre-clerkship medical curriculums consist of a series of organ system-based courses and lectures but often lack an integration between organ systems. Such integration could be beneficial for clerkship years and students' future career. Hence, we aimed to share our process of organising an integrative teaching approach in a large class of pre-clerkship medical students and to reflect the students' perspective toward the teaching process in this observational study. In addition, we tested effectiveness of this integrative approach compared with the traditional teaching (lecture).

METHODS

We organised a two-dimensional (2D)-integrative teaching for 309 students in selected topics of cardiovascular physiology of the medical curriculum of the Faculty of Medicine, Chulalongkorn University, Thailand. The first dimension of integration is the incorporation of physiology of other organ systems into the cardiovascular physiology class. The second is the integration of multiple teaching methods and strategies, including small group discussion, student presentation, wrap-up, quiz, and question-and-answer sessions. Unless opting out, students evaluated this integrative teaching by filling in a questionnaire. The summative scores were also used to determine their comprehensive understandings of the content.

RESULTS

The course evaluation showed that most students (81.9-91.2%) had positive attitudes toward all organised sessions, i.e. this teaching method helps promote their basic and applied physiology knowledge, critical thinking, information searching, presentation, and teamwork skills. In general, students at all performance levels attained higher scores in the summative exam for the 2D-integrative-class-relevant questions (74.4±16.1%) than for the lecture-pertinent questions (65.2±13.6%).

CONCLUSIONS

In a large class size of pre-clerkship students, 2D-integrative teaching strategies with careful planning and preparation can be successfully implemented, based on positive attitudes and relatively high summative scores of students in this study. Hence, this comprehensive teaching could be incorporated in current medical curriculums, particularly for the complex learning topics.

Effects of intradialytic cycling exercise on daily physical activity, physical fitness, body composition, and clinical parameters in high-volume online hemodiafiltration patients: a pilot randomized-controlled trial

PURPOSE

The mortality of dialysis patients treated with high-volume online hemodiafiltration (OL-HDF) is better than hemodialysis, but is still higher than healthy population. Low daily physical activity increases cardiovascular mortality. Addition of intradialytic exercise (IDX) program might improve physical activity and health status in OL-HDF patients. This pilot open-labeled randomized-controlled trial was conducted to evaluate the effects of IDX on physical activity and other clinical parameters in OL-HDF patients.

METHODS

Twelve OL-HDF patients were randomized into control (n = 6) or IDX (n = 6) groups. The subjects in IDX group were trained to exercise using a cycle ergometer for 60 min during each OL-HDF session. Physical activity measured as daily step count using a wrist-worn triaxial accelerometer, physical fitness, or cardiorespiratory fitness assessed by VO₂max and other physical performance tests, lean body mass determined by the Dual-energy X-ray absorptiometry (DXA), quality of life (QOL), and various parameters were compared between baseline and 6 months.

RESULTS

The baseline physical activity status was comparable. Following 6-month IDX, the physical activity was significantly improved in IDX group [+ 1048.79 (+ 741.50, + 2792.54) vs. - 362.06 (- 1626.82, - 167.47) steps/day, p = 0.01], while physical fitness and QOL were unchanged. The lean body mass parameters were preserved in the IDX group while seemed to decrease in the control group. Serum albumin was significantly increased in the IDX group (p = 0.01). The hemoglobin changes were significantly better (p = 0.01) and the erythropoietin resistance index was significantly lower in the IDX group (p = 0.03). Phosphate reduction was significantly greater in the IDX group (p = 0.04).

CONCLUSIONS

IDX could improve physical activity and other metabolic parameters in OL-HDF patients and these might contribute to further improvement in clinical and survival outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Registration: NCT03353844.

A high-MUFA diet alone does not affect ketone body metabolism, but reduces glycated hemoglobin when combined with exercise training in diabetic rats

Background

Monounsaturated fat (MUFA) also has glucose-lowering action, but its effect on ketone bodies is unknown.

Objectives

To examine the effects of high-MUFA diet alone or in combination with exercise training, which can improve glucose and ketone body metabolism, in a rat model of diabetes.

Methods

Wistar rats were administered streptozotocin to induce diabetes and then randomly divided into five groups: sedentary rats fed a regular diet (1), a high-saturated-fat diet (2), a high-MUFA diet (3); and exercisetrained rats fed a regular diet (4), and a high-MUFA diet (5). Training was by a treadmill twice daily, 5 days/week. At 12 weeks, glucose, glycated hemoglobin (HbA1c), insulin, nonesterified fatty acids (NEFA), and β-hydroxybutyrate levels were measured in cardiac blood. Activity of the overall ketone synthesis pathway was determined in liver and 3-ketoacyl-CoA transferase activity determined in gastrocnemius muscle.

Results

A high-MUFA diet tended to lower plasma glucose without affecting other biochemical variables. Training did not change glucose metabolism, but significantly reduced serum NEFA. Only the high-MUFA diet plus training significantly decreased HbA1c levels. Hepatic ketone synthesis was decreased and 3-ketoacyl-CoA transferase activity was increased by training alone or in combination with a high-MUFA diet. Changes in NEFA, β-hydroxybutyrate, and the enzymatic activities in response to training plus a high-MUFA diet were comparable to those caused by training alone.

Conclusion

A high-MUFA diet alone does not alter ketone body metabolism. Combination of a MUFA-rich diet and exercise training is more effective than either MUFA or exercise alone for lowering HbA1c.

Effects of Precooling with Cold Water Ingestion on Thermoregulatory Response of Obese Men during Moderate Intensity Exercise in Hot and Humid Environment

OBJECTIVE

1) To determine rectal temperature (Tre) and fluid loss (FL) of obese men (OM) compared to non-obese men (NM) during exercise in cool conditions (CC) and hot and humid conditions (HC), and 2) to investigate the effects of cold water (CW; 0.5 ± 0.5°C) ingestion before exercise in HC in OM MATERIAL AND METHOD: Twelve OM and 12 NM completed 2 treadmill exercise sessions, in CC and HC, in a randomized order Each session was performed for 30 minutes at 45-50% of heart rate reserve with a 5-minute warm up and 5-minute cool down.

RESULTS

There were no differences in Tre in response to exercise between OM and NM both in CC (OM 37.77 ± 0.08°C, NM 37.68 ± 0.08°C; p = 0.463) and in HC (OM 37.82 ± 0.06°C, NM 37.85 ± 0.06°C; p = 0.725). Heart rate, perceived exertion and thermal sensations were not significantly different between OM and NM. However, compared to NM, fluid loss (FL) was approximately 160 mL greater in OM (OM 443.33 ± 98.65 mL, NM 283.33 ± 108.15 mL; p ≤ 0.001) in CC, and was 194 mL greater (OM 632.50 ± 126.57 mL, NM 438.33 ± 126.62 mL; p ≤ 0.001) in HC. In HC, the 12 OM performed additional 2 bouts of exercise, with CW vs. ambient temperature water (AW; 30.5 ± 0.5°C) ingestions prior to the start of exercise. Precooling with CW ingestion, compared to AW ingestion, showed no significant difference in Tre but CW was able to reduce FL (CW 646.67 ± 139.82 mL, AW 735 ± 126.95 mL; p = 0.010).

CONCLUSION

OM may continuously exercise about 30 minutes at moderate intensity in HC without the increase of Tre to dangerous levels. However, OM should drink approximately 200 mL more water in HC and 160 mL more water in CC than NM. Precooling with CW ingestion is a good method of reducing risk of exertional heat illnesses in obese individuals during exercise in HC, as it decreases the amount of FL induced by exercise.

Enhanced peritubular capillary flow and renal function can be accomplished in normoalbuminuric type 2 diabetic nephropathy

Under common practice, treatment of diabetic nephropathy (DN) is usually initiated at late stage of CKD due to the insensitiveness of the available diagnostic markers. Such treatment fails to restore renal perfusion and function. This is due to the defective mechanism of vascular homeostasis and impaired nitric oxide production observed in late stage of DN. In contrast, the mechanism of vascular repair is adequately functional in early stage of DN (normoalbuminuria). In this study, we treated 50 normoalbuminuric diabetic patients with multidrug vasodilators, namely ACE inhibitor, angiotensin receptor blocker, ± calcium channel blocker in conjunction with correction of metabolic disorders for 24-36 months. Following the treatment, increment in peritubular capillary flow in response to vasodilators was observed, and thus supports the adequate role of vascular repair. In addition, increase in renal function documented in this study also implies that an effective preventive strategy to minimize end-stage renal disease can be accomplished in normoalbuminuric DN.

N-acetylcysteine attenuates oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis

AIM: To evaluate attenuating properties of N-acetylcysteine (NAC) on oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis (NASH).

METHODS: Male Sprague-Dawley rats were randomly divided into three groups. Group 1 (control, n = 8) was free accessed to regular dry rat chow (RC) for 6 wk. Group 2 (NASH, n = 8) was fed with 100% fat diet for 6 wk. Group 3 (NASH + NAC₂₀, n = 9) was fed with 100% fat diet plus 20 mg/kg per day of NAC orally for 6 wk. All rats were sacrificed to collect blood and liver samples at the end of the study.

RESULTS: The levels of total glutathione (GSH) and hepatic malondialdehyde (MDA) were increased significantly in the NASH group as compared with the control group (GSH; 2066.7 ± 93.2 vs 1337.5 ± 31.5 μmol/L and MDA; 209.9± 43.9 vs 3.8 ±1.7 μmol/g protein, respectively, P < 0.05). Liver histopathology from group 2 showed moderate to severe macrovesicular steatosis, hepatocyte ballooning, and necroinflammation. NAC treatment improved the level of GSH (1394.8 ± 81.2 μmol/L, P < 0.05), it did not affect MDA (150.1 ± 27.0 μmol/g protein), but led to a decrease in fat deposition and necroinflammation.

CONCLUSION: NAC treatment could attenuate oxidative stress and improve liver histology in rats with NASH.

Ginseng supplementation does not change lactate threshold and physical performances in physically active Thai men

BACKGROUND

Ginseng has been one of the most popular herbs said to improve human exercise performance. Unclear and anecdotal information is known about the effect of ginseng on lactate threshold and aerobic performance in humans.

OBJECTIVE

The purpose of the present study was to investigate the effect of ginseng supplementation on lactate threshold in physically active young men.

MATERIAL AND METHOD

Sixty men from the Naval Medical Corps, Royal Thai Navy, aged 17- 22 years old, were randomized into either the ginseng (n = 30) or placebo (n = 30) group. The ginseng group took 3 grams of 100% ginseng orally, while the placebo group took an equal amount of lactose powder each day, for 8 weeks. Blood lactic acid levels for determination of lactate threshold (LT) were measured during an incremental cycle ergometer work. LT exercise performance, and heart rate (HR) responses to exercise were determined at baseline and after 8 weeks of ginseng and placebo consumption. Substrate oxidation rates during steady state exercise were assessed upon study completion. Selected markers for liver and kidney functions, including serum aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine were monitored for possible side effects of ginseng.

RESULTS

L T before and after 8 weeks of supplementation in the ginseng group (164.5 +/- 32.8 and 170.9 +/- 26.4 watts), and in the placebo group (163.7 + 25.1 and 163.7 + 17.3 watts) were not different (p = 0.448). Both groups had a similar pattern of exercise heart rate (p = 0.918), total exercise time (p = 0.241), and peak power output (p = 0.411). After 8 weeks, the magnitude of difference between ginseng and placebo groups on oxidation rates of fat (3.82 +/- 10.0 cal. kg(-1). min(-1), p = 0.704) or carbohydrate (4.36 +/- 12.6 cal. kg(-1). min(-1), p = 0.731) was not statistically significant. There were no abnormal changes of markers of liver and renal functions after ginseng administration.

CONCLUSION

Daily administration of 3 g of ginseng for an 8-week period did not improve LT nor did it affect physical performances. Therefore, ginseng supplementation did not exert an ergogenic property on aerobic fitness enhancement in well-fit individuals.

Effects of N-acetylcysteine on oxidative stress in rats with non-alcoholic steatohepatitis

OBJECTIVE

Prove the attenuated effects of N-acetylcysteine (NAC) on oxidative stress in rats with nonalcoholic steatohepatitis (NASH).

MATERIAL AND METHOD

Male Sprague-Dawley rats were randomly divided into five groups. Group I (normal control) was fed regular dry rat chow (RC) for 6 weeks. Group 2 (NASH) was fed 100% fat diet for 6 weeks. Group 3-5 were fed 100% fat diet for 6 weeks, and then switched to RC alone (NASH + diet ; group 3), to RC + 20 mg/kg/day of NAC orally (NASH + diet + NAC20; group 4) or to RC + 500 mg/kg/day of NAC orally (NASH + diet + NAC500; group 5) for 4 weeks, respectively. They were sacrificed to collect blood and liver samples at the end of the present study.

RESULTS

Levels of total glutathione (GSH), serum cholesterol, and hepatic malondialdehyde (MDA) were increased significantly in the NASH group compared with normal control. Liver histopathology from group 2 showed moderate to severe macrovesicular steatosis, hepatocyte ballooning, and necroinflammation. Treatment with diet or diet plus NAC reduced the levels of GSH, cholesterol, and hepatic MDA back to normal. Liver sections from group 3-5 showed a decrease in fat deposition and necroinflammation in hepatocytes. However, no differences on all variables existed between diet alone and diet plus NAC groups.

CONCLUSION

Our data indicate that diet or diet plus NAC treatment could attenuate oxidative stress and improve liver histopathology of NASH. However the addition of NAC is not better than diet treatment alone.

FABP2 Ala54Thr genotype is associated with glucoregulatory function and lipid oxidation after a high-fat meal in sedentary nondiabetic men and women

BACKGROUND

A common functional missense mutation [Ala54Thr of the fatty acid-binding protein 2 gene (FABP2)] has previously been studied for associations with glucoregulation, postprandial lipemia, and lipid oxidation rates. However, most of those studies have not accounted for the interactive and potentially confounding effects of habitual physical activity and diet.

OBJECTIVE

We tested the hypothesis that, in sedentary nondiabetic subjects following a low-fat diet, Thr54 FABP2 carriers have lower glucoregulatory function, greater postprandial lipemia, and greater lipid oxidation rates than do their Ala54 FABP2-homozygous counterparts.

DESIGN

Men and women (n = 122) aged 50-75 y who were following a low-fat diet were genotyped and underwent oral-glucose-tolerance tests. A subgroup (n = 36) also underwent postprandial lipemia tests with lipid oxidation rate measurements.

RESULTS

Thr54 carriers were less likely to have normal glucose tolerance (P = 0.05) and had higher fasting glucose concentrations (P = 0.003) than did Ala54 homozygotes. In Thr54 carriers, the insulin sensitivity index was lower (P = 0.02), and the fasting insulin and the oral-glucose-tolerance test insulin area under the curve were higher (P = 0.05 and 0.03, respectively) than in Ala54 homozygotes. FABP2 genotype was not associated with fasting or postprandial lipemia test triacylglycerol or free fatty acids (P > or = 0.22 for all), but postprandial lipid oxidation rates were higher (P = 0.01), which suggests that fat absorption is higher in Thr54 carriers than in Ala54 homozygotes.

CONCLUSIONS

In sedentary nondiabetic persons following a low-fat diet, FABP2 Thr54 carriers have lower glucose tolerance and lower insulin action than do Ala54-homozygous persons. Furthermore, FABP Thr54 carriers have higher lipid oxidation rates, which may be the mechanism of glucoregulatory dysfunction.

Genetic Markers of Fibrinolytic Responses of Older Persons to Exercise Training

We assessed the interactive effect of genetic polymorphisms and exercise training on fibrinolysis in 50 - 75 yr old men (n = 17) and women (n = 28). Subjects had tissue plasminogen activator (t-PA) antigen levels and activity and plasminogen activator inhibitor-1 (PAI-1) activity measured before and after 6 mo of endurance-exercise training. Subject's DNA was typed for the PAI-1 4 G/5 G and t-PA I/D variants. Baseline PAI-1 activity, t-PA activity, and t-PA antigen levels were not different among PAI-1 or t-PA genotype groups. Overall, exercise training did not change PAI-1 activity (- 0.43 +/- 0.81 IU/mL, p = NS), increased t-PA activity (0.37 +/- 0.16 IU/mL, p = 0.02), and decreased t-PA antigen levels (- 0.88 +/- 0.20 ng/mL, p < 0.001). Although the differences in changes with training were not significant among genotype groups, significant t-PA antigen level improvements were evident only in PAI-1 4 G allele carriers and significant t-PA activity increases only in PAI-1 4 G homozygotes. t-PA genotype affected the training-induced t-PA antigen level improvements (p = 0.033) after covarying for gender and baseline t-PA antigen levels, with the smallest and largest reductions in the D homozygotes and I/D heterozygotes, respectively. These findings could have important treatment implications for the use of exercise training to reduce CV disease and thrombotic risk in older men and women.

Human gender differences in fibrinolytic responses to exercise training and their determinants

Endurance exercise training improves fibrinolysis, but this training-induced adaptation may differ somewhat between men and women. We sought to determine whether the potential gender differences in training-induced changes in selected fibrinolysis measures were related to changes in adiposity and/or plasma lipoprotein lipid levels. Seventeen men and 28 women, 50-75 years old, who were generally overweight to obese, were assessed for plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA) activity, t-PA antigen and plasma lipoprotein-lipid levels, and body composition before and after 6 months of endurance exercise training while on a low-fat diet. At baseline, there were no differences in fibrinolytic measures between the men and women. Baseline levels of these fibrinolytic markers in both men and women were primarily related to other fibrinolytic measures and body composition, with a smaller contribution from plasma high-density lipoprotein cholesterol (HDL-C) levels. Exercise training reduced t-PA antigen levels in both men and women, but the reduction was significantly greater in men (-1.6 +/- 0.3 versus -0.5 +/- 0.2 ng ml(-1), P = 0.007). Exercise training decreased PAI-1 activity more in men than in women (-2.6 +/- 1.4 versus +0.9 +/- 0.9 IU ml(-1), P = 0.03). Men and women both showed increased t-PA activity with exercise training to the same extent (+0.38 +/- 0.12 versus +0.36 +/- 0.24 U ml(-1)). The changes in fibrinolytic measures with exercise training in men and women were correlated with changes in other fibrinolytic measures, although in men abdominal fat changes were a strong predictor of fibrinolytic changes with training. These findings suggest that training-induced improvements in endogenous fibrinolysis markers are somewhat greater in men compared to women and may be more strongly associated with abdominal obesity in men.

Endurance training-induced changes in the insulin response to oral glucose are associated with the peroxisome proliferator-activated receptor-gamma2 Pro12Ala genotype in men but not in women

The present study sought to investigate, in sedentary men and women, (a) whether a common functional gene variant (peroxisome proliferator-activated receptor-gamma2 [PPARgamma2] Pro12Ala) predicts insulin action and (b) whether improvements in insulin action in response to endurance exercise training are associated with PPARgamma2 Pro12Ala. Sedentary, 50- to 75-year-old men and women (N = 73) were genotyped and underwent oral glucose tolerance tests (OGTTs) before and after 6 months of endurance training. At baseline, men heterozygous for the Pro12Ala variant had a greater OGTT insulin area under the curve (AUC) as compared with Pro12 homozygous men (P = .009). Endurance training resulted in a significantly greater improvement in insulin AUC in Pro12Ala heterozygous men as compared with Pro12 homozygous men (P = .003) despite no genotype-specific differences with respect to training-induced changes in body weight, body mass index, and percent body fat. No differences between genotype groups were present at baseline or in response to training in women. Training did not alter the OGTT glucose AUC for the group as a whole, and the baseline, final, and change in glucose AUC were not dependent on PPARgamma2 genotype and/or sex. In conclusion, these findings suggest that sedentary men with the PPARgamma2 Pro12Ala variant have lower insulin action on glucose disposal as compared with their counterparts. However, these men are particularly responsive with respect to the magnitude of endurance training-induced improvement in insulin action.

Influence of the interleukin-6 -174 G/C gene polymorphism on exercise training-induced changes in glucose tolerance indexes

A polymorphism in the IL-6 gene, a G-to-C substitution 176 bp upstream of the ATG translation initiation site, has been associated with diabetes prevalence and insulin resistance. Interventions including exercise training are frequently used to modify cardiovascular disease risk factors. Consequently, this project examined associations between the IL-6 -174 genotype and oral glucose tolerance test outcomes in 50- to 75-yr-old sedentary men and postmenopausal women before and after aerobic exercise training. Among the 87 individuals who started the study, 56 were retested after 6 mo of aerobic exercise training. Subject characteristics at baseline did not differ between the IL-6 genotype groups with the exception of fasting glucose, which was higher (P = 0.02, covariates age, gender, and ethnicity) in the CC genotype group. The training-induced change in glucose area under the curve during the oral glucose tolerance test varied between the IL-6 -174 genotype groups (P = 0.05, covariates age, gender, ethnicity, baseline glucose area under the curve, and percent body fat change) with a significant decrease occurring only in the GG genotype group. Insulin outcomes did not differ among the groups at baseline or after training. Training-induced changes in weight, percent body fat, maximal oxygen consumption, fasting glucose, and an insulin sensitivity index also changed similarly among the genotype groups. In conclusion, fasting glucose and the extent to which glucose tolerance changes with exercise training may be influenced by the IL-6 -174 gene polymorphism.

Plasma nitrate/nitrite response to an oral glucose load and the effect of endurance training

To assess the role of circulating nitric oxide (NO) production in glucose homeostasis, plasma nitrate/nitrite (NO(x)) was assessed during oral glucose tolerance tests (OGTTs) on 64 sedentary subjects and in a subset 40 subjects before and after 6 months of endurance exercise training. NO(x) decreased with the oral glucose load (P </=.001 for linear and quadratic effects). OGTT NO(x) response indices (NO(x) response area (NO(x) AREA), change in NO(x) from baseline to the minimum (DeltaNO(x)), and NO(x) time-to-minimum) were not associated with OGTT insulin or glucose areas under the curve (AUCs) or with insulin sensitivity index (ISI). Training did not alter NO(x) AREA, or DeltaNO(x), however, NO(x) time-to-minimum occurred later after training (P =.038). Training-induced insulin AUC and ISI changes were not associated with OGTT NO(x) index changes; however, glucose total AUC changes were associated with changes in NO(x) AREA (r =.42, P =.007) and DeltaNO(x) (r =.37, P =.019). In conclusion, these data suggest that circulating NO production is not involved in glycemic control after an oral glucose load in sedentary adults. In response to endurance training, however, it appears that the time required to reach minimum NO(x) levels after a glucose load is greater after training. Furthermore, although the magnitude of NO(x) response (as indicated by NO(x) AREA and DeltaNO(x)) to an oral glucose load does not appear to change with training for all individuals, individual training-induced changes in the NO(x) response magnitude are partly explained by training-induced changes in OGTT glucose responses.

Selected genetic polymorphisms and plasma coagulation factor VII changes with exercise training

We assessed the effects of coagulation factor VII (FVII) gene polymorphisms, lipid-related polymorphisms, and exercise training-induced plasma lipoprotein lipid changes on FVII level changes with exercise training in middle- to older-aged men and women. Forty-six healthy sedentary men and women were stabilized on a low-fat diet and then underwent baseline testing, 6 mo of endurance exercise training, and final testing. Plasma FVII-Ag levels decreased with exercise training (106.7 ± 1.4 vs. 104.2 ± 1.6%, P = 0.005). There were no significant differences in FVII-Ag changes with exercise training between -323 (0/10 bp)/-401 (G/T) haplotype or -402 (G/A) genotype groups. FVII-Ag changes with training were not correlated with changes in plasma lipoprotein lipids. In linear regression analyses, FVII-Ag changes with training remained significant after adjusting for training-induced plasma lipoprotein lipid changes ( P = 0.01). FVII changes with training were associated with apolipoprotein E genotype ( P = 0.012); this relationship was still evident after adjusting for training-induced plasma lipoprotein lipid changes ( P = 0.047). FVII changes with training also were significantly associated with human ATPase binding cassette-1 genotype ( P = 0.018); this relationship persisted after accounting for the effect of the training-induced plasma lipoprotein lipid changes ( P = 0.045). We conclude that plasma FVII-Ag changes with exercise training are more closely related to selected lipid-related genotypes than FVII gene promoter variants.

A single bout of walking exercise enhances endogenous fibrinolysis in stroke patients

PURPOSE

Impaired endogenous fibrinolysis is an important predictor for increased risk of stroke and myocardial infarction. Acute exercise can enhance fibrinolysis, primarily by stimulating short-term increases in plasma tissue plasminogen activator (tPA), which is postulated to protect against atherothrombotic events. No prior studies have examined the fibrinolytic response to exercise in stroke survivors despite their high risk for recurrent stroke and myocardial infarction. The purpose of this study was to assess the fibrinolytic response to acute submaximal exercise in chronic hemiparetic stroke patients.

METHODS

Eighteen (16 men, 2 women) untrained stroke patients with chronic hemiparetic gait deficits volunteered for participation in this single session exercise study. Fasting blood samples for determination of tPA and plasminogen activator inhibitor (PAI-1) enzyme activities were obtained before, immediately after, and 60 min after submaximal treadmill walking. Patients walked at 60% maximal heart rate reserve (low-moderate intensity) for a cumulative total of 20 min.

RESULTS

The exercise bout increased tPA activity by 79% (P < 0.01) and decreased PAI-1 activity by 18% (P < 0.01). At 1 h after completing the walking exercise, plasma tPA activity levels were still significantly elevated (43%,P < 0.01), and PAI-1 activity levels were 25% lower (P < 0.01) than baseline.

CONCLUSIONS

These findings demonstrate that a single bout of aerobic walking exercise can improve fibrinolysis profiles in chronic stroke patients. Significant increases in endogenous tPA and reductions in PAI-1 activity persist for at least 1 h after exercise cessation. The implications are that alterations in physical activity during the day may modify clot lysing potential, thereby affecting atherothrombotic risk.