Takuro Tobina

Effect of Low-Intensity Aerobic Exercise on Insulin-Like Growth Factor-I and Insulin-Like Growth Factor-Binding Proteins in Healthy Men

Increased concentrations of circulating insulin-like growth factor-I (IGF-I) or IGF-I relative to IGF-binding proteins (IGFBPs) are associated with increased risk of developing several forms of cancer. Conversely, exercise is linked with reduced risk. This study aims to investigate the effect of a low-intensity exercise program on circulating levels of IGF-I, IGFBP-1, and IGFBP-3, in previously sedentary males. Fourteen healthy men participated in cycle ergometer training at lactate threshold intensity for 60 min/day, 5 days/week for 6 weeks. After aerobic training, insulin sensitivity improved by 20%, while fasting insulin levels decreased by 13%. Simultaneously, low-intensity aerobic training decreased the circulating levels of IGF-I by 9%, while IGFBP-1 levels increased by 16%. An interesting finding was that higher pretraining level of IGF-I was associated with greater decline in IGF-I with training. Insulin-sensitizing low-intensity aerobic exercise is thus considered to be an effective method for downregulating IGF-I and upregulating IGFBP-1 levels.

Lifestyle Intervention Involving Calorie Restriction with or without Aerobic Exercise Training Improves Liver Fat in Adults with Visceral Adiposity

Objective. To evaluate the effect of calorie restriction-induced weight loss with or without aerobic exercise on liver fat. Methods. Thirty-three adults with visceral adiposity were divided into calorie restriction (CR; n = 18) or CR and aerobic exercise (CR + Ex; n = 15) groups. Target energy intake was 25 kcal/kg of ideal body weight. The CR + Ex group had a targeted exercise time of 300 min/wk or more at lactate threshold intensity for 12 weeks. Results. Reductions in body weight (CR, −5.3 ± 0.8 kg; CR + Ex, −5.1 ± 0.7 kg), fat mass (CR, −4.9 ± 0.9 kg; CR + Ex, −4.4 ± 0.6 kg), and visceral fat (CR, −24 ± 5 cm2; CR + Ex, −37 ± 5 cm2) were not statistically different between groups. Liver fat decreased significantly in both groups, with no difference between groups. Change in maximal oxygen uptake was significantly greater in the CR + Ex group than in the CR group (CR, −0.7 ± 0.7 mL/kg/min; CR + Ex, 2.9 ± 1.0 mL/kg/min). Conclusion. Both CR and CR + Ex resulted in an improved reduction in liver fat; however, there was no additive effect of exercise training.

Physical Function Is Weakly Associated with Angiotensin-Converting Enzyme Gene I/D Polymorphism in Elderly Japanese Subjects

Background: The turning point in the deterioration of physical function seems to occur between the ages of 70 and 80 years. In particular, muscle strength may decline even more in subjects older than 75. A recent study found that the angiotensin-converting enzyme (ACE) genotype also affects physiological left ventricular hypertrophy. A very limited number of papers have examined genetic differences in resistance and endurance forms of a single sporting discipline. Objective: The purpose of this study was to evaluate the relationship between ACE genotype and physical function by controlling the known confounding factors including dental status. Methods:We selected 431 subjects who were aged 76 years and did not require special care for their daily activities. We conducted a medical examination, followed by 5 physical function tests, as follows: (1) maximum hand grip strength, (2) maximal isometric knee extensor strength, (3) maximal stepping rate for 10 s, (4) one-leg standing time with eyes open and (5) 10-meter maximum walking speed. Subjects were genotyped for the ACE intron 16 Alu insertion. In addition, serum concentrations of total cholesterol, total protein, IgA and IgG were measured at a commercial laboratory. The Eichner index was used as an indicator of occlusal condition. Multiple linear regression analysis was performed to evaluate the relationship between the ACE gene insertion/deletion (I/D) polymorphism and physical function considering confounding factors. Results: The ACE gene I/D polymorphism was positively associated with hand grip strength and 10-meter maximum walking speed. Betas of hand grip strength were 0.09 for I/D (p = 0.022) and 0.12 for insertion/insertion (I/I; p = 0.004). Betas of 10-meter walking speed were –0.11 for I/D (p = 0.093) and –0.14 for I/I (p = 0.039). Dental status such as Eichner index class C was significantly associated with one-leg standing time with eyes open (beta –0.11; p = 0.028). Conclusion: This study suggests that there is a significant relationship between ACE genotype and physical function. In particular, subjects with the ACE deletion/deletion genotype were associated with upper extremities.

Minute-by-minute stepping rate of daily physical activity in normal and overweight/obese adults

SUMMARY The relationship between minute-by-minute stepping rate under free-living and obesity remains unclear. The purpose of the present investigation was to compare the levels of physical activity (PA) based on the minute-by-minute stepping rate under free-living conditions between normal weight (NW) and overweight and obese (OV) individuals. A total 40 volunteers participated in the present investigation. These participants were divided into NW or OV according to the body mass index (<25 kg m(-2) or 25 kg m(-2)). All participants wore a pedometer with a uni-axial accelerometer (Lifecorder-EX 4sec, Kenz, Japan) for 7 days continuously. The Lifecorder determined the number of steps and time spent in PA at <100, 100-129, 130 steps min(-1) according to the minute-by-minute stepping rate. The OV group took a significantly fewer number of steps per day in comparison to that in the NW group (p < 0.05). The average daily stepping rate was significantly lower in the OV group in comparison to that in the NW group (p = 0.01). Furthermore, the OV group spent a significantly shorter time in PA at a 100 steps min(-1) of the stepping rate compared with that in the NW group (p < 0.05). These results indicate that obese individuals spent significantly shorter time in PA at 100 steps min(-1) of stepping rate in comparison to the NW individuals.:

relationships between fat deposition in the liver and skeletal muscle and insulin sensitivity in Japanese individuals: a pilot study

Purpose: To evaluate the relationships between insulin sensitivity (IS), body fat accumulation, and aerobic capacity in middle- to older-aged Japanese participants with visceral adiposity. Participants and methods: Aerobic capacity was measured during an incremental ramp exercise test. Computed tomography was used to measure visceral (VFA) and subcutaneous (SFA) fat area, the fat in liver-to-spleen ratio (L/S), and low-density skeletal muscle area (LDMA). IS was assessed using euglycemic-hyperinsulinemic clamps. Results: A total of 11 males and 9 females, age 58 ± 9 years (mean ± standard deviation), body mass index 29 ±4.1 kg/m2, and VFA 190 ±53 cm2 participated in this study. In unadjusted models, VFA, LDMA, and L/S were significantly correlated with IS, which remained in adjusted models for LDMA and L/S, but not for VFA. In multiple stepwise regression analysis including sex, age, body fat, VFA, SFA, alcohol consumption, and aerobic capacity (oxygen uptake at the lactate threshold), L/S, and LDMA accounted for 70% of the total variance in IS. Percentage body fat and SFA, but not VFA, were significantly correlated with high molecular-weight adiponectin levels (r = 0.58, P < 0.01 and r = 0.54, P < 0.05, respectively). IS and L/S were significantly and negatively correlated with tumor necrosis factor-α (r = −0.67 and −0.63, respectively; both P < 0.01) and plasminogen activator inhibitor-1 (r = −0.58, P < 0.01 and −0.52, P < 0.05, respectively), whereas LDMA was not. Conclusion: These findings indicate that ectopic fat deposition in the liver and skeletal muscle may be associated with peripheral IS independently of body fat accumulation and aerobic capacity in middle- to older-aged Japanese individuals with visceral adiposity. Because of the small sample size, additional larger studies are needed to provide further insight into these preliminary findings.

Regulation of Muscle Genes by Moderate Exercise

Moderate-intensity exercise at the lactate threshold (LT) is considered to be a safe and effective training regimen for improving metabolic syndrome. The aim of the current study was to investigate the effects of moderate exercise performed at the LT on skeletal muscle gene expression. 6 healthy men participated in cycle ergometer training at LT, 60 min/d, 5 d/wk for 12 wks. Muscle samples were collected after 5 d of training, and then 2 d after training at wks 6 and 12. Quantitative real-time PCR analysis revealed that the expression of peroxisome proliferator activated receptor co-activated 1alpha was significantly increased at 1 h after the training session on day 5. Moreover, using serial analysis gene expression, we found that moderate training for 6 and 12 wks simultaneously induced the expression of a number of metabolic genes involved in the TCA cycle, beta-oxidation, and electron transport. Furthermore, several genes encoding antioxidant enzymes and contractile apparatus were induced. The expression levels of 233 novel transcripts were also altered in response to moderate exercise. Thus, moderate training at the LT is a sufficient stimulus to induce the expression of numerous genes implicated in the development of metabolic syndrome, transcripts involved in the contractile apparatus, and novel transcripts.

A 12-week aerobic exercise program without energy restriction improves intrahepatic fat, liver function and atherosclerosis-related factors

SUMMARY OBJECTIVE To study the effects of a 12-week continuous aerobic exercise program without energy restriction on intrahepatic fat, indices of liver function (aspartate aminotransferase [AST], alanine aminotransferase [ALT] and γ-glutamyl transpeptidase [γGTP]), plasminogen activator inhibitor-1 (PAI-1) and insulin resistance (HOMA-IR). METHODS Subjects were divided into two groups based on the degree of intrahepatic fat accumulation at baseline (high liver fat [HLF]: n = 13; low liver fat [LLF]: n = 14). Participants were instructed to exercise for more than 300 min per week at the lactate threshold. Fat accumulation (intramuscular, intrahepatic, visceral and subcutaneous fat) was evaluated by computed tomography. Blood samples were taken to determine the levels of AST, ALT, PAI-1, glucose and insulin. RESULTS Weight, body mass index, body fat, visceral fat and subcutaneous fat decreased significantly in both groups between baseline and post-intervention (P < 0.05), but were not significantly different between the two groups (P > 0.05). Intrahepatic fat, AST, ALT and PAI-1 improved significantly between baseline and post-intervention in the HLF group (P < 0.05; AST, P = 0.052), and improvements were significantly greater than those in the LLF group (P < 0.05). γGTP decreased significantly in the HLF group between baseline and post-intervention (P < 0.05), but was not significantly different between the two groups (P > 0.05). HOMA-IR did not significantly improve between baseline and post-intervention either within or between the two groups (P > 0.05). CONCLUSION This study revealed that a 12-week continuous aerobic exercise program without energy restriction might improve intrahepatic fat, liver function and atherosclerosis-related factors.

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.

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.

Physical activity cut‐offs and risk factors for preventing child obesity in Japan

There is no official recommendations for physical activity level or steps for preventing and improving child obesity in Japan.