Effects of high-intensity intermittent exercise versus moderate-intensity continuous exercise on renal hemodynamics assessed by ultrasound echo.

High-intensity intermittent exercise (HIIE) has become attractive for presenting a variety of exercise conditions. However, the effects of HIIE on renal function and hemodynamics remain unclear. This study aimed to compare the effects of HIIE and moderate-intensity continuous exercise (MICE) on renal hemodynamics, renal function, and kidney injury biomarkers. Ten adult males participated in this study. We allowed the participants to perform HIIE or MICE to consider the impact of exercise on renal hemodynamics under both conditions. Renal hemodynamic assessment and blood sampling were conducted before the exercise (pre) and immediately (post 0), 30 min (post 30), and 60 min (post 60) after the exercise. Urine sampling was conducted in the pre, post 0, and post 60 phases. There was no condition-by-time interaction (p = 0.614), condition (p = 0.422), or time effect (p = 0.114) regarding renal blood flow. Creatinine-corrected urinary neutrophil gelatinase-associated lipocalin concentrations increased at post 60 (p = 0.017), but none exceeded the cut-off values for defining kidney injury. Moreover, there were no significant changes in other kidney injury biomarkers at any point. These findings suggest that high-intensity exercise can be performed without decreased RBF or increased kidney injury risk when conducted intermittently for short periods.

The differences in renal hemodynamic response following high-intensity exercise between younger and older males.

BACKGROUND: Renal blood flow (RBF) decreases with exercise, but this change is only temporary, and habitual exercise may be an effective method to improve renal function. The kidney shows structural and functional changes with aging, but it is unclear how aging affects the hemodynamic response of the kidneys to exercise. Therefore, we evaluated the differences in the hemodynamic response of the kidneys to high-intensity exercise between younger and older men. METHODS: Sixteen men (8 young and 8 older) underwent an incremental exercise test using a cycle ergometer with a 1-min warm up followed by exercise at 10-20 W/min until the discontinuation criteria were met. Renal hemodynamics were assessed before exercise, immediately after exercise, and at 60-min after exercise using ultrasound echo. RESULTS: High-intensity exercise significantly reduced RBF in both groups (younger: ∆ - 53 ± 16%, p = 0.0005; older: ∆ - 53 ± 19%, p = 0.0004). In the younger group, RBF returned to the pre-exercise level 60-min after exercise (∆ - 0.4 ± 5.7%, p > 0.9999). In contrast, RBF 60-min after exercise was significantly lower than that before exercise in the older group (∆ - 24 ± 19%, p = 0.0006). The older group had significantly lower RBF than younger adults 60-min after exercise (423 ± 32 vs. 301 ± 98 mL/min, p = 0.0283). CONCLUSIONS: Our findings demonstrate that RBF following high-intensity exercise recovered 60-min after exercise in younger group, whereas RBF recovery was delayed in the older group.

The Validity of Ultra-Short-Term Heart Rate Variability during Cycling Exercise.

Ultra-short-term heart rate variability (HRV) has been validated in the resting state, but its validity during exercise is unclear. This study aimed to examine the validity in ultra-short-term HRV during exercise considering the different exercise intensities. HRVs of twenty-nine healthy adults were measured during incremental cycle exercise tests. HRV parameters (Time-, frequency-domain and non-linear) corresponding to each of the 20% (low), 50% (moderate), and 80% (high) peak oxygen uptakes were compared between the different time segments of HRV analysis (180 s (sec) segment vs. 30, 60, 90, and 120-sec segments). Overall, the differences (bias) between ultra-short-term HRVs increased as the time segment became shorter. In moderate- and high-intensity exercises, the differences in ultra-short-term HRV were more significant than in low intensity exercise. Thus, we discovered that the validity of ultra-short-term HRV differed with the duration of the time segment and exercise intensities. However, the ultra-short-term HRV is feasible in the cycling exercise, and we determined some optimal time duration for HRV analysis for across exercise intensities during the incremental cycling exercise.

The moderate-intensity continuous exercise maintains renal blood flow and does not impair the renal function.

Exercise is restricted for individuals with reduced renal function because exercising reduces blood flow to the kidneys. Safe and effective exercise programs for individuals with reduced renal function have not yet been developed. We previously examined the relationship between exercise intensity and renal blood flow (RBF), revealing that moderate-intensity exercise did not reduce RBF. Determining the effects of exercise duration on RBF may have valuable clinical applications. The current study examined the effects of a single bout of continuous exercise at lactate threshold (LT) intensity on renal hemodynamics. Eight adult males participated in this study. Participants underwent 30 min of aerobic exercise at LT intensity using a cycle ergometer. Evaluation of renal hemodynamics was performed before and after exercise, in the recovery phase using ultrasound echo. Furthermore, blood and urine samplings were conducted before and after exercise, in the recovery phase. Compared with resting, RBF was not significantly changed immediately after continuous exercise (319 ± 102 vs. 308 ± 79 ml/min; p = 0.976) and exhibited no significant changes in the recovery phase. Moreover, urinary kidney injury molecule-1 (uKIM-1) level exhibited no significant change immediately after continuous exercise (0.52 ± 0.20 vs. 0.46 ± 0.27 µg/g creatinine; p = 0.447). In addition, the results revealed no significant change in urinary uKIM-1 in 60-min after exercise. Other renal injury biomarkers exhibited a similar pattern. These findings indicate that a single bout of moderate-intensity continuous exercise maintains RBF and does not induce renal injury.

The Association between Decreased Kidney Function and FIB-4 Index Value, as Indirect Liver Fibrosis Indicator, in Middle-Aged and Older Subjects.

Liver fibrosis might be linked to the prevalence of chronic kidney disease (CKD). However, there is little information about the association between liver fibrosis and decreased kidney function in middle-aged and older subjects. We aimed to evaluate the influence of liver fibrosis on the incidence or prevalence of CKD stage 3-5 in a retrospective cross-sectional study (Study 1, n = 806) and a 6-year longitudinal study (Study 2, n = 380) of middle-aged and older subjects. We evaluated liver fibrosis using the Fibrosis-4 (FIB-4) index and kidney function using the estimated glomerular filtration rate (eGFR) of all subjects. All subjects were divided into four groups on the basis of their FIB-4 score quartiles (low to high). In the Jonckheere-Terpstra trend test of Study 1, the eGFR decreased significantly from the lowest group to the highest group (p < 0.001). The Kaplan-Meier survival curve in Study 2 showed that the cumulative prevalence of CKD stage 3-5 was higher in the third quartile than the other quartiles. Our results suggest that liver fibrosis could be a useful indicator for the prevalence of CKD, even within a relatively healthy population, although liver fibrosis was not an independent risk factor.

Effect of exercise intensity on renal blood flow in patients with chronic kidney disease stage 2.

BACKGROUND: Acute exercise reduces renal blood flow (RBF). However, the effect of exercise intensity on RBF in patients with chronic kidney disease (CKD) stage 2 is not known. We investigated the association between RBF and exercise intensity in patients with CKD stage 2 using pulsed Doppler ultrasonography. METHODS: Eight men with CKD stage 2 (cystatin C-based estimate of glomerular filtration rate: 60-89 ml/min/1.73 m2) participated in this study. Using a bicycle ergometer, participants undertook a maximal graded exercise test (MGET) (experiment 1) and a multi-stage exercise test (experiment 2) to determine their lactate threshold (LT). Participants undertook a multi-stage exercise test for 4-min each. Workloads of 60%, 80%, 100%, 120%, and 140% of LT were used in experiment 3. RBF was measured by pulsed Doppler ultrasonography at rest, immediately after exercise, and 1 h after exercise in experiment 1, and at rest and immediately after each exercise bout in experiment 3. RESULTS: Renal blood flow after the MGET was 52% lower than at rest, and did not recover as well as after the exercise test. Cross-sectional area (CSA) was significantly lower after graded exercise. RBF tended to be lower at 100% of LT and was significantly lower at 120% of LT. CSA was significantly lower at 100% of LT. CONCLUSIONS: Renal blood flow does not change during exercise until the LT is reached. These findings may assist in making appropriate exercise recommendations to patients with CKD stage 2.

Long-term Body Weight Gain After Maturity is Associated With the Incidence of Chronic Kidney Disease (CKD), Independent of Current Body Weight, in Middle-aged and Older Men.

BACKGROUND: This study investigated the relationship between long-term body weight gain after maturity and the incidence of chronic kidney disease (CKD). METHODS: The participants were 303 men without a history of cardiovascular and cerebrovascular diseases, kidney dysfunction, or dialysis treatment. Their body weight gain after maturity was examined using a standardized self-administered questionnaire. The participants were divided into two groups based on the presence/absence of a body weight gain of ≥10 kg since 20 years of age. RESULTS: After a 6-year follow-up, the cumulative incidence of CKD was significantly higher in participants with a body weight gain of ≥10 kg than in participants without body weight a body weight gain of ≥10 kg since 20 years of age (log-rank test: P = 0.041). After adjusting for the age, body mass index, estimated glomerular filtration rate levels, smoking and drinking habits, and the presence of hypertension, dyslipidemia, and hyperglycemia at baseline, the normal body weight participants with a body weight gain of ≥10 kg since 20 years of age was significantly related to the incidence of CKD (hazard ratio 2.47; 95% confidence of interval, 1.02-6.01, P = 0.045). CONCLUSIONS: These results suggest that long-term body weight gain after maturity in normal body weight participants may be associated with the incidence of CKD, independent of current body weight.

Short- and long-term effects of high-fat diet feeding and voluntary exercise on hepatic lipid metabolism in mice.

Exercise is an effective tool for improving high-fat diet induced fat accumulation in the liver. However, the process of fat accumulation in the liver and the efficacy of early intervention with exercise remain unclear. The aim of this study was to investigate the short- and long-term effects of high-fat diet feeding and voluntary exercise on hepatic lipid metabolism in mice. Male C57BL/6J mice aged 6 weeks were randomly divided into two groups, the control group and high-fat diet feeding group, and fed a normal or high-fat diet for 12 weeks. After 6 weeks, mice in the high-fat diet feeding group were further divided into no exercise group and voluntary exercise training group, with mice in the exercise group provided a running wheel for 6 weeks. Body weight, food intake, and wheel rotation counts were measured every second day for 12 weeks. We found that voluntary exercise for 1 week (short-term exercise) significantly reduced fat accumulation in the liver by downregulating the expression of hepatic lipogenesis-associated proteins and upregulating the expression of hepatic lipolysis-associated proteins, as determined through western blotting and histology. Further, voluntary exercise for 6 weeks (long-term exercise) downregulated the expression of hepatic lipogenesis-associated proteins. These results suggest that hepatic lipogenesis and/or hepatic lipolysis mediate the beneficial effects of voluntary exercise on hepatic fat accumulation.

Association between exercise intensity and renal blood flow evaluated using ultrasound echo.

BACKGROUND: High-intensity exercise reduces renal blood flow (RBF) and may transiently exacerbate renal dysfunction. RBF has previously been measured invasively by administration of an indicator material; however, non-invasive measurement is now possible with technological innovations. This study examined variations in RBF at different exercise intensities using ultrasound echo. METHODS: Eight healthy men with normal renal function (eGFRcys 114 ± 19 mL/min/1.73 m2) participated in this study. Using a bicycle ergometer, participants underwent an incremental exercise test using a ramp protocol (20 W/min) until exhaustion in Study 1 and the lactate acid breaking point (LaBP) was calculated. Participants underwent a multi-stage test at exercise intensities of 60, 80, 100, 120, and 140% LaBP in Study 2. RBF was measured by ultrasound echo at rest and 5 min after exercise in Study 1 and at rest and immediately after each exercise in Study 2. To determine the mechanisms behind RBF decline, a catheter was placed into the antecubital vein to study vasoconstriction dynamics. RESULTS: RBF after maximum exercise decreased by 51% in Study 1. In Study 2, RBF showed no significant decrease until 80% LaBP, and showed a significant decrease (31%) at 100% LaBP compared with at rest (p < 0.01). The sympathetic nervous system may be involved in this reduction in RBF. CONCLUSIONS: RBF showed no significant decrease until 80% LaBP, and decreased with an increase in blood lactate. Reduction in RBF with exercise above the intensity at LaBP was due to decreased cross-sectional area rather than time-averaged flow velocity.

The joint impact of habitual exercise and glycemic control on the incidence of chronic kidney disease (CKD) in middle-aged and older males.

BACKGROUND: This retrospective study evaluated the influence of the joint impact of habitual exercise and glycemic control on the incidence of chronic kidney disease (CKD) during a 6-year follow-up period in middle-aged and older males. METHODS: The study population included 303 males without a history of cardiovascular disease, stroke, renal dysfunction, or dialysis treatment. Their lifestyle behaviors regarding exercise and physical activity were evaluated using a standardized self-administered questionnaire. The participants were divided into four categories according to the performance or non-performance of habitual exercise and the presence or absence of hyperglycemia. RESULTS: After 6 years, 32 subjects (10.6%) developed CKD (estimated glomerular filtration rate < 60 ml/min/1.73 m2 and/or proteinuria). The cumulative incidence of CKD was significantly higher among subjects who did not perform habitual exercise and hyperglycemic subjects (log-rank test: p < 0.05, respectively). According to a Cox proportional hazards model, the hazard ratio (HR) for the incidence of CKD in subjects with a normal glucose tolerance (NGT) who did not perform habitual exercise (HR = 2.82, 95% confidence of interval (CI) = 1.07-7.36, p = 0.034) and that in hyperglycemic subjects who did not perform habitual exercise (HR = 5.89, 95% CI = 1.87-16.63, p = 0.003) were significantly higher in comparison to the subjects with a NGT who performed habitual exercise. CONCLUSIONS: These results suggest that the habitual exercise and good glycemic control and their combination were associated with the incidence of CKD.

Hypertension and hyperglycemia and the combination thereof enhances the incidence of chronic kidney disease (CKD) in middle-aged and older males.

AIM: Chronic kidney disease (CKD) may be an etiologic cause of aging, hypertension, diabetes mellitus (DM), and metabolic syndrome. However, the influence of these cardiovascular risk factors and their combination on the development of CKD remains controversial. This retrospective study evaluated the influence of cardiovascular risk factors and their combination on the incidence of CKD during a 6-year follow-up period in middle-aged and older males. METHODS: The subjects were 303 males without a history of cardiovascular disease, stroke, renal dysfunction, or dialysis treatment. A biochemical analysis, blood pressure (BP) analysis, and anthropometry measurements were performed every year, and the classification of CKD was also assessed based on the estimated glomerular filtration rate (<60 ml/min/1.73 m2) and/or presence of proteinuria. RESULTS: After 6 years, the incidence of CKD was noted in 32 subjects. According to a multivariable analysis, hypertension (hazard ratio [HR]: 3.95, 95% confidence of interval [CI]: 1.64-9.49, p = 0.002) and hyperglycemia (HR: 3.27, 95% CI: 1.42-7.56, p = 0.006) were significantly associated with the incidence of CKD. According to a Cox proportional hazards model, the HR for the incidence of CKD was significantly higher in the combination of high-normal BP/hypertension and impaired fasting glucose/DM group than in the combination of normotensive and normal glucose tolerance group (HR: 7.16, 95% CI: 2.43-17.25, p = 0.001). CONCLUSIONS: These results suggest that the hypertension and hyperglycemia and their combination may be associated with the incidence of CKD.

The association between changes in lifestyle behaviors and the incidence of chronic kidney disease (CKD) in middle-aged and older men.

BACKGROUND: This study was designed to evaluate whether changes in lifestyle behaviors are correlated with the incidence of chronic kidney disease (CKD). METHODS: The subjects consisted of 316 men without a history of cardiovascular disease, stroke, or renal dysfunction or dialysis treatment. The following lifestyle behaviors were evaluated using a standardized self-administered questionnaire: habitual moderate exercise, daily physical activity, walking speed, eating speed, late-night dinner, bedtime snacking, skipping breakfast, and drinking and smoking habits. The subjects were divided into four categories according to the change in each lifestyle behavior from baseline to the end of follow-up (healthy-healthy, unhealthy-healthy, healthy-unhealthy and unhealthy-unhealthy). RESULTS: A multivariate analysis showed that, with respect to habitual moderate exercise and late-night dinner, maintaining an unhealthy lifestyle resulted in a significantly higher odds ratio (OR) for the incidence of CKD than maintaining a lifestyle (OR 8.94; 95% confidence interval [CI], 1.10-15.40 for habitual moderate exercise and OR 4.00; 95% CI, 1.38-11.57 for late-night dinner). In addition, with respect to bedtime snacking, the change from a healthy to an unhealthy lifestyle and maintaining an unhealthy lifestyle resulted in significantly higher OR for incidence of CKD than maintaining a healthy lifestyle (OR 4.44; 95% CI, 1.05-13.93 for healthy-unhealthy group and OR 11.02; 95% CI, 2.83-26.69 for unhealthy-unhealthy group). CONCLUSIONS: The results of the present study suggest that the lack of habitual moderate exercise, late-night dinner, and bedtime snacking may increase the risk of CKD.

The Association Between Unhealthy Lifestyle Behaviors and the Prevalence of Chronic Kidney Disease (CKD) in Middle-Aged and Older Men.

BACKGROUND: This cross-sectional study evaluated the association between unhealthy lifestyle behaviors and the prevalence of chronic kidney disease (CKD) in middle-aged and older men. METHODS: The subjects included 445 men without a history of cardiovascular disease, stroke, or dialysis treatment, who were not taking medications. Unhealthy lifestyle behaviors were evaluated using a standardized self-administered questionnaire and were defined as follows: 1) lack of habitual moderate exercise, 2) lack of daily physical activity, 3) slow walking speed, 4) fast eating speed, 5) late-night dinner, 6) bedtime snacking, and 7) skipping breakfast. The participants were divided into four categories, which were classified into quartile distributions based on the number of unhealthy lifestyle behaviors (0-1, 2, 3, and ≥4 unhealthy behaviors). RESULTS: According to a multivariate analysis, the odds ratio (OR) for CKD (defined as estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m(2) and/or proteinuria) was found to be significantly higher in the ≥4 group than in the 0-1 group (OR 4.67; 95% confidence interval [CI], 1.51-14.40). Moreover, subjects' lack of habitual moderate exercise (OR 3.06; 95% CI, 1.13-8.32) and presence of late-night dinner (OR 2.84; 95% CI, 1.40-5.75) and bedtime snacking behaviors (OR 2.87; 95% CI, 1.27-6.45) were found to be significantly associated with the prevalence of CKD. CONCLUSIONS: These results suggest that an accumulation of unhealthy lifestyle behaviors, especially those related to lack of habitual moderate exercise and presence of late-night dinner and bedtime snacking may be associated with the prevalence of CKD.

The accumulation of healthy lifestyle behaviors prevents the incidence of chronic kidney disease (CKD) in middle-aged and older males.

AIM: This study was retrospectively designed to evaluate the influence of healthy lifestyle behaviors on the incidence of chronic kidney disease (CKD) during a 5-year follow-up period in middle-aged and older males. METHODS: The subjects included 252 males without a history of cardiovascular disease, stroke, renal dysfunction and/or dialysis treatment who were not taking any medications. Their lifestyle behaviors were evaluated using a standardized self-administered questionnaire and defined as follows: (1) habitual moderate exercise, (2) daily physical activity, (3) fast walking speed, (4) slow eating speed, (5) no late-night dinner, (6) no bedtime snacking and (7) no skipping breakfast. The participants were divided into four categories, which were classified into quartile distributions according to the number of healthy lifestyle behaviors (7-6, 5, 4 and ≤3 groups). RESULTS: After 5 years, the incidence of CKD [estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2) and/or proteinuria] was observed in 23 subjects (9.1%). The Kaplan-Meier survival curves showed that the cumulative incidence of CKD significantly decreased according to an increase in the number of healthy lifestyle behaviors (log-rank test: p = 0.003). According to a multivariate analysis, habitual moderate exercise [hazard ratio (HR) 0.20, 95% confidence of interval (CI) 0.06-0.69, p = 0.011] and no bedtime snacking (HR 0.19, 95 % CI 0.08-0.48, p = 0.004) were significantly associated with the incidence of CKD. CONCLUSIONS: These results suggest that the accumulation of healthy lifestyle behaviors, especially those related to habitual moderate exercise and no bedtime snacking, is considered to be important to reduce the risk of CKD.