[Physical parameters and physical function in older drivers with driving-related anxiety: the Nakagawa Study].

AIM: This study investigated whether driving-related anxiety was independently associated with physical parameters and physical function in community-dwelling older people. METHODS: Participants were 523 community-dwelling older drivers (353 men and 170 women). Participants self-reported driving-related anxiety when driving in familiar environments, and completed physical assessments: visual impairment, auditory impairment, cerebrovascular disease (CVD), hand grip strength, knee extension strength, timed up and go (TUG), chair stand, one leg standing with open eyes, functional reach, vertical jump, preferred gait speed and maximal gait speed. Participants were divided into a driving-related anxiety group (72.8±5.1 years; 21 men, seven women) and a no-anxiety (non-anxiety) group (70.7±4.7 years; 325 men, 163 women). We examined physical performance differences between the anxiety and non-anxiety groups using analysis of covariance, and investigated the relationship between anxiety, physical function and performance using logistic regression analysis (forward stepwise selection). RESULTS: The driving-related anxiety group was significantly older, with higher rates of visual impairment, auditory impairment, and CVD than the non-anxiety group. The anxiety group exhibited independently poorer TUG and maximal gait speed (P<0.05 for both). Logistic regression analysis revealed significant relationships between anxiety and visual impairment (odds ratio [OR]: 5.6, 95% confidence interval [CI]: 2.5-12.6), auditory impairment (OR: 3.0, 95% CI: 1.3-7.0), TUG (OR: 1.46, 95% CI: 1.1-1.9) and CVD (OR: 3.1, 95% CI: 1.0-9.4) (P<0.05 for all). CONCLUSIONS: Driving-related anxiety was significantly associated with worse physical performance, visual impairment, auditory impairment, and CVD in community-dwelling older drivers.

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.

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.

Effects of a 12-week, short-interval, intermittent, low-intensity, slow-jogging program on skeletal muscle, fat infiltration, and fitness in older adults: randomized controlled trial.

PURPOSE: We developed a short-interval, low-intensity, slow-jogging (SJ) program consisting of sets of 1 min of SJ at walking speed and 1 min of walking. We aimed to examine the effects of an easily performed SJ program on skeletal muscle, fat infiltration, and fitness in older adults. METHODS: A total of 81 community-dwelling, independent, older adults (70.8 ± 4.0 years) were randomly assigned to the SJ or control group. The SJ group participants were encouraged to perform 90 min of SJ at their anaerobic threshold (AT) intensity and 90 min of walking intermittently per week. Aerobic capacity at the AT and sit-to-stand (STS) scores were measured. Intracellular water (ICW) in the legs was assessed by segmental multi-frequency bioelectrical impedance analysis. Subcutaneous (SAT) and intermuscular (IMAT) adipose tissue and muscle cross-sectional area (CSA) were measured at the mid-thigh using computed tomography. RESULTS: A total of 75 participants (37 SJ group, 38 controls) completed the 12-week intervention. The AT and STS improved in the SJ group compared with the controls (AT 15.7 vs. 4.9 %, p < 0.01; STS 12.9 vs. 4.5 %, p < 0.05). ICW in the upper leg increased only in the SJ group (9.7 %, p < 0.05). SAT and IMAT were significantly decreased only in the SJ group (p < 0.01). CONCLUSION: The 12-week SJ program was easily performed by older adults with low skeletal muscle mass, improved aerobic capacity, muscle function, and muscle composition in older adults.

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 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.

Effects of environmental enrichment in aged mice on anxiety-like behaviors and neuronal nitric oxide synthase expression in the brain.

Previous studies have shown that an enriched environment (EE) has an important effect on brain function via the neuronal nitric oxide synthase/nitric oxide (nNOS/NO) pathway in young and aged animals. However, whether EE induces its effect by altering nNOS expression levels and whether it lowers anxiety-like behaviors in aged mice remains unclear. Here, we show that nNOS expression levels increased with age in the hippocampus and cerebellum in aged mice, but not in the cortex. Moreover, EE reduced anxiety-like behaviors in aged mice and reduced nNOS expression levels in the cerebellum, but not in the cortex. The present study suggests that EE improves anxiety-like behaviors in aged mice by altering nNOS expression levels in the hippocampus or cerebellum.

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.

Effects of 2 weeks of low-intensity cycle training with different pedaling rates on the work rate at lactate threshold.

PURPOSE: This study examined (1) the effects of a single bout of exercise at different pedaling rates on physiological responses, pedal force, and muscle oxygenation, and (2) the effects of 2 weeks of training with different pedaling rates on work rate at lactate threshold (WorkLT). METHODS: Sixteen healthy men participated in the study. An incremental exercise test involving pedaling a cycling ergometer at 50 rpm was conducted to assess maximal oxygen consumption and WorkLT. The participants performed constant workload, submaximal exercise tests at WorkLT intensity with three different pedaling rates (35, 50, and 75 rpm). Oxygen consumption ([Formula: see text]O2), blood pressure, heart rate (HR), blood lactate, and pedal force were measured and oxy-hemoglobin/myoglobin concentration (OxyHb/Mb) at vastus lateralis was monitored by near-infrared spectroscopy during exercise. The participants were then randomly assigned to cycling exercise training at WorkLT in either the low or high frequency pedaling rate (LFTr, 35 rpm or HFTr, 75 rpm) group. Each 60-min training session was performed five times/week. RESULTS: Despite maintaining the same work rate, [Formula: see text]O2 and HR were significantly lower at 35 than 75 rpm. Conversely, integrated pedal force was significantly higher at 35 than 75 rpm. Peripheral OxyHb/Mb was significantly lower at 35 than 75 rpm. After 2 weeks of training, WorkLT normalized to body mass significantly increased in the LFTr, but not the HFTr group. CONCLUSIONS: Pedaling rate and the corresponding pedal force and peripheral oxygenation during cycling exercise influence the effect of training at LT on WorkLT.

Product of heart rate and first heart sound amplitude as an index of myocardial metabolic stress during graded exercise.

BACKGROUND: The double product (DP) breakpoint of heart rate (HR) and systolic blood pressure has been identified as coincident with anaerobic threshold (AT), but there are no simple methods for measuring cardiac metabolic stress (CMS) during an exercise test. It was hypothesized that the DP of HR and the amplitude of the first heart sound (AHS1) (DP-AHS1) would reflect CMS, and thus, the breakpoint in the DP-AHS1 (DPBP-AHS1) could be an alternative method for determining AT. METHODS AND RESULTS: Subjects (age range, 18-73 years) were recruited to perform a graded exercise test on a cycle ergometer with continuous monitoring of DP-AHS1, with left ventricular pressure (LVP; experiment 1, Ex1), plasma catecholamine and blood lactate (experiment 2, Ex2) and gas exchange (experiment 3, Ex3). Ex1: in all subjects there was a strong correlation between AHS1 and LVdP/dtmax (r=0.94-0.98), and between the DP-AHS1 and the triple product of HR, LVdP/dtmax, and max LVP (r=0.98-0.99). Ex2: DP-AHS1 was strongly correlated with adrenaline (r=0.97-1.00) and lactate (r=0.96-1.00) levels in all subjects. Ex3: there was a strong correlation between DPBP-AHS1, AT and maximum oxygen consumption. CONCLUSIONS: The present simple measure of DP-AHS1 can reflect plasma adrenaline and lactate levels during graded exercise testing. Further, DPBP-AHS1 is a surrogate marker of AT and a good index of functional aerobic capacity.

Long-term effects of home-based bench-stepping exercise training on healthcare expenditure for elderly Japanese.

BACKGROUND: We examined the long-term effects of home-based bench-stepping exercise training on total healthcare expenditure (TOHEX) and number of outpatient visits (NOVIS) in elderly adults. METHODS: A total of 189 elderly Japanese (age 73 ± 4 years) participated in this study. They were randomly assigned to either an exercise or control group. TOHEX, NOVIS, and outpatient expenditure (OPEX) were evaluated every 6 months from 1 year before the start to the end of the intervention period, as well as 1 year after the end of the intervention. The exercise group was encouraged to perform home-based bench-stepping exercise training on most, and preferably all, days of the week for 18 months. RESULTS: The exercise group showed significant increases in lactate threshold as compared with pre-intervention values. There were no significant differences in TOHEX, OPEX, or NOVIS between the exercise and control groups 1 year before the start of the intervention, and the values remained similar during the first 12 months of the intervention period. However, at 18 months, TOHEX, NOVIS, and OPEX were significantly lower in the exercise group than in the control group (TOHEX: 170 007 ± 192 072 vs. 294 705 ± 432 314 yen, P = 0.008; NOVIS: 19.2 ± 26.3 vs. 28.2 ± 32.1 days, P = 0.012; OPEX: 132 973 ± 132 016 vs. 187 799 ± 158 167 yen, P = 0.005). CONCLUSIONS: The data indicate that a long-term home-based bench-stepping exercise program can reduce healthcare expenditure in elderly Japanese.

The utilization of a biopsy needle to obtain small muscle tissue specimens to analyze the gene and protein expression.

Recent analytical methods such as real-time polymerase chain reaction (PCR) and Western blotting have now enabled us to analyze the gene and protein expression from small amounts of tissue. A fine needle muscle biopsy is thus expected to obtain a minimally sufficient amount of skeletal muscle to make a successful analysis. As a result, we used this fine needle muscle biopsy technique to obtain muscle tissue specimens from the vastus lateral muscle in 40 participants. The amount of tissue obtained by the fine needle was 5.2 +/- 3.2 mg (mean +/- standard deviation). The total RNA extracted was 3.0 +/- 1.4 microg and the total protein extracted was 2203 +/- 1541 microg. Furthermore, the skeletal muscle tissue specimens obtained by the regular needle technique and blood sample were used as the control. Those specimens were used to measure the gene expression of beta-myosin heavy chain slow (beta-MHC slow) by real-time PCR and the protein expression of monocalboxylate transporter 1 (MCT-1) by Western blotting. Beta-MHC slow gene expression was detected in both samples obtained by a fine and a regular needle biopsy, but not in a blood sample. Furthermore, the MCT-1 protein was detected in samples obtained by a fine needle muscle biopsy. These results indicated that the fine needle muscle biopsy is therefore a useful technique to obtain skeletal muscle specimens at least to analyze the gene and protein expression.

Role of selected polymorphisms in determining muscle fiber composition in Japanese men and women.

Genetic polymorphisms and sex differences are suggested to affect muscle fiber composition; however, no study has investigated the effects of genetic polymorphisms on muscle fiber composition with respect to sex differences. Therefore, the present study examined the effects of genetic polymorphisms on muscle fiber composition with respect to sex differences in the Japanese population. The present study included 211 healthy Japanese individuals (102 men and 109 women). Muscle biopsies were obtained from the vastus lateralis to determine the proportion of myosin heavy chain (MHC) isoforms (MHC-I, MHC-IIa, and MHC-IIx). Moreover, we analyzed polymorphisms in α-actinin-3 gene ( ACTN3; rs1815739 ), angiotensin-converting enzyme gene ( ACE; rs4341 ), hypoxia-inducible factor 1 α gene ( rs11549465 ), vascular endothelial growth factor receptor 2 gene ( rs1870377 ), and angiotensin II receptor, type 2 gene ( rs11091046 ), by TaqMan single-nucleotide polymorphism genotyping assays. The proportion of MHC-I was 9.8% lower in men than in women, whereas the proportion of MHC-IIa and MHC-IIx was higher in men than in women (5.0 and 4.6%, respectively). Men with the ACTN3 RR + RX genotype had a 4.8% higher proportion of MHC-IIx than those with the ACTN3 XX genotype. Moreover, men with the ACE ID + DD genotype had a 4.7% higher proportion of MHC-I than those with the ACE II genotype. Furthermore, a combined genotype of ACTN3 R577X and ACE insertion/deletion (I/D) was significantly correlated with the proportion of MHC-I ( r = -0.23) and MHC-IIx ( r = 0.27) in men. In contrast, no significant correlation was observed between the examined polymorphisms and muscle fiber composition in women. These results suggest that the ACTN3 R577X and ACE I/D polymorphisms independently affect the proportion of human skeletal muscle fibers MHC-I and MHC-IIx in men but not in women. NEW & NOTEWORTHY In men, the RR + RX genotype of the α-actinin-3 gene ( ACTN3) R577X polymorphism was associated with a higher proportion of myosin heavy chain (MHC)-IIx. The ID + DD genotype of the angiotensin-converting enzyme gene ( ACE) insertion/deletion (I/D) polymorphism, in contrast to a previous finding, was associated with a higher proportion of MHC-I in men. In addition, the combined genotype of these polymorphisms was correlated with the proportion of MHC-I and MHC-IIx in men. Thus ACTN3 R577X and ACE I/D polymorphisms influence the muscle fiber composition in Japanese men.

Angiotensin I converting enzyme gene polymorphism and exercise trainability in elderly women: an electrocardiological approach.

Angiotensin I converting enzyme (ACE) gene Insertion / Deletion (I/D) polymorphism is associated with exercise trainability and exercise induced left ventricular hypertrophy. However, it is unclear whether this polymorphism influences exercise trainability in the elderly, and the electrocardiological alterations by exercise training is unknown among the genotypes. We herein investigated the association between ACE gene insertion/deletion (I/D) polymorphism, exercise trainability and the electrocardiological alternations by exercise in elderly women. Eighty four elderly women participated in this study. In all subjects the leg extension power (LEP) and lactate threshold (LT) were determined in order to evaluate the muscle strength, aerobic capacity and to also select the appropriate training intensity for each individual. They performed bench step exercise training for 12 weeks. A resting electrocardiogram was recorded for the obtained QTc interval in before and after the program. The baseline of aerobic capacity was higher in I/I than that in I/D, and the QTc interval was shorter in I/I than that in I/D. All other characteristics were similar among the genotypes. The QTc interval tended to be shorten only in the D/D. Furthermore, the value of the QTc interval change showed a significant difference between the I/I and D/D genotype after the program. The LT and LEP demonstrated a similar response among the genotypes. The D allele of ACE gene I/D polymorphism may therefore play a role in the electrocardiological aspect during exercise training, however, it was not found to influence the aerobic capacity. Key pointsThe D allele of ACE gene I/D polymorphism may play a role in the electrocardiological aspects during exercise trainingACE gene I/D polymorphism was not determined the aerobic capacity and leg strength in elderly people.The ACE gene I/D polymorphism did not influence aerobic and strength trainability in elderly people.

Peroxisome proliferator-activated receptor gamma co-activator 1 gene Gly482Ser polymorphism is associated with the response of low-density lipoprotein cholesterol concentrations to exercise training in elderly Japanese.

Muscle peroxisome proliferator-activated receptor gamma co-activator 1 (PGC-1)α gene expression is influenced by the Gly482Ser gene polymorphism, which is a candidate genetic risk factor for diabetes mellitus and obesity. This study investigated the effects of PGC-1 gene Gly482Ser polymorphisms on alterations in glucose and lipid metabolism induced by exercise training. A 12-week intervention study was performed for 119 participants who were more than 65 years of age and completed exercise training at lactate threshold intensity. Total cholesterol and low-density lipoprotein cholesterol were significantly reduced in Gly/Gly but not in Gly/Ser and Ser/Ser participants after exercise. The Gly/Gly genotype of the PGC-1 gene Gly482Ser polymorphism influences the effects of moderate-intensity exercise training on low-density lipoprotein cholesterol and total cholesterol concentrations in older people.

Slowed response to peripheral visual stimuli during strenuous exercise.

Recently, we proposed that strenuous exercise impairs peripheral visual perception because visual responses to peripheral visual stimuli were slowed during strenuous exercise. However, this proposal was challenged because strenuous exercise is also likely to affect the brain network underlying motor responses. The purpose of the current study was to resolve this issue. Fourteen participants performed a visual reaction-time (RT) task at rest and while exercising at 50% (moderate) and 75% (strenuous) peak oxygen uptake. Visual stimuli were randomly presented at different distances from fixation in two task conditions: the Central condition (2° or 5° from fixation) and the Peripheral condition (30° or 50° from fixation). We defined premotor time as the time between stimulus onset and the motor response, as determined using electromyographic recordings. In the Central condition, premotor time did not change during moderate (167±19ms) and strenuous (168±24ms) exercise from that at rest (164±17ms). In the Peripheral condition, premotor time significantly increased during moderate (181±18ms, P<0.05) and strenuous exercise (189±23ms, P<0.001) from that at rest (173±17ms). These results suggest that increases in Premotor Time to the peripheral visual stimuli did not result from an impaired motor-response network, but rather from impaired peripheral visual perception. We conclude that slowed response to peripheral visual stimuli during strenuous exercise primarily results from impaired visual perception of the periphery.

Cognitive function at rest and during exercise following breakfast omission.

It has been suggested that breakfast omission, as opposed to breakfast consumption, has the detrimental effects on cognitive function. However, the effects of acute exercise following breakfast omission on cognitive function are poorly understood, particularly during exercise. The purpose of this study was to examine the interactive effects of breakfast and exercise on cognitive function. Ten participants completed cognitive tasks at rest and during exercise in the breakfast consumption or omission conditions. Blood glucose concentration was measured immediately after each cognitive task. We used cognitive tasks to assess working memory [Spatial Delayed Response (DR) task] and executive function [Go/No-Go (GNG) task]. The participants cycled ergometer for 30 min while keeping their heart rate at 140 beats·min(-1). Accuracy of the GNG task was lower at rest in the breakfast omission condition than that in the breakfast consumption condition (Go trial: P=0.012; No-Go trial: P=0.028). However, exercise improved accuracy of the Go trial in the breakfast omission condition (P=0.013). Reaction time in the Go trial decreased during exercise relative to rest in both conditions (P=0.002), and the degree of decreases in reaction time was not different between conditions (P=0.448). Exercise and breakfast did not affect the accuracy of the Spatial DR task. The present results indicate that breakfast omission impairs executive function, but acute exercise improved executive function even after breakfast omission. It appears that beneficial effects of acute exercise on cognitive function are intact following breakfast omission.

Timed Up and Go test, atrophy of medial temporal areas and cognitive functions in community-dwelling older adults with normal cognition and mild cognitive impairment.

AIM: This study aimed to ascertain if performance on the Timed Up and Go (TUG) test is associated with indicators of brain volume and cognitive functions among community-dwelling older adults with normal cognition or mild cognitive impairment. METHODS: Participants were 80 community-dwelling older adults aged 65-89years (44 men, 36 women), including 20 with mild cognitive impairment. Participants completed the TUG and a battery of cognitive assessments, including the Mini-Mental State Examination (MMSE), the Logical Memory I and II (LM-I, LM-II) subtests of the Wechsler Memory Scale-Revised; and the Trail Making Test A and B (TMT-A, TMT-B). Bilateral, right- and left-side medial temporal area atrophy as well as whole gray and white matter indices were determined with the Voxel-based Specific Regional Analysis System for Alzheimer's Disease. We divided participants into three groups based on TUG performance: "better" (≤6.9s); "normal" (7-10s); and "poor" (≥10.1s). RESULTS: Worse TMT-A and TMT-B performance showed significant independent associations with worse TUG performance (P<0.05, P<0.01 for trend, respectively). After adjusting for covariates, severe atrophy of bilateral, right-, and left-side medial temporal areas were significantly independently associated with worse TUG performance (P<0.05 for trend). However, no significant associations were found between MMSE, LM-I, LM-II, whole gray and white matter indices, and TUG performance. CONCLUSIONS: Worse TUG performance is related to poor performance on TMT-A and TMT-B, and is independently associated with severe medial temporal area atrophy in community-dwelling older adults.

Effect of moderate exercise training on peripheral glucose effectiveness, insulin sensitivity, and endogenous glucose production in healthy humans estimated by a two-compartment-labeled minimal model.

For examining the effects of moderate exercise training on peripheral glucose effectiveness (S(g)(2)*), insulin sensitivity (S(i)(2)*), and endogenous glucose production (EGP), seven men and one woman (24.8 +/- 1.8 years) participated in cycle ergometer training at lactate threshold intensity for 60 min/day, 5 days/week for 12 weeks. Stable-labeled frequently sampled intravenous glucose tolerance tests were performed before and 16 h and 1 week after the last training session. S(g)(2)* (pre 0.71 +/- 0.03 x 10(-2), 16 h 0.85 +/- 0.02 x 10(-2) dl. kg(-1). min(-1)) and S(i)(2)* (pre 12.6 +/- 2.6 x 10(-4), 16 h 19.7 +/- 3.3 x 10(-4) dl. kg(-1). min(-1). [ micro U/ml](-1)), analyzed using the two-compartment minimal model, were significantly elevated 16 h after the last training session. The elevated S(g)(2)* remained higher despite the cessation of exercise training for 1 week (1.00 +/- 0.03 x 10(-2) dl. kg(-1). min(-1)). EGP was suppressed within 20 min after glucose bolus, and the suppression of EGP was followed by their overshoot. The time course of EGP during the intravenous glucose tolerance test remained similar after the training period. In conclusion, moderate exercise training at lactate threshold improves not only peripheral insulin sensitivity but also peripheral glucose effectiveness with no change in the effect of glucose and/or insulin to suppress EGP in healthy humans.