Motohiko Miyachi

Unfavorable effects of resistance training on central arterial compliance: a randomized intervention study.

Background—Reductions in the compliance of central arteries exert a number of adverse effects on cardiovascular function and disease risk. Endurance training is efficacious in increasing arterial compliance in healthy adults. We determined the effects of resistance training on carotid arterial compliance using the intervention study design. Methods and Results—Twenty-eight healthy men 20 to 38 years old were randomly assigned to the intervention group (n=14) and the control group (n=14). Control subjects were instructed not to alter their normal activity levels throughout the study period. Intervention subjects underwent 3 supervised resistance training sessions per week for 4 months and detraining for a subsequent 4 months. The resistance training increased maximal strength in all muscle groups tested (P<0.001). There were no significant differences in baseline arterial compliance and &bgr;-stiffness index between the intervention and control groups. In the intervention group, carotid arterial compliance decreased 19% (P<0.05), and &bgr;-stiffness index increased 21% (P<0.01) after resistance training. These values returned completely to the baseline levels during the detraining period. Arterial compliance did not change in the control group. In both groups, there were no significant changes in brachial and carotid blood pressure, carotid intima-media thickness, lumen diameter, and femoral arterial compliance. Changes in carotid artery compliance were significantly and negatively related to corresponding changes in left ventricular mass index (r=−0.56, P<0.001) and left ventricular hypertrophy index (r=−0.68, P<0.001). Conclusions—In marked contrast to the beneficial effect of regular aerobic exercise, several months of resistance training “reduces” central arterial compliance in healthy men.

Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max.

This study consists of two training experiments using a mechanically braked cycle ergometer. First, the effect of 6 wk of moderate-intensity endurance training (intensity: 70% of maximal oxygen uptake (VO2max), 60 min.d-1, 5 d.wk-1) on the anaerobic capacity (the maximal accumulated oxygen deficit) and VO2max was evaluated. After the training, the anaerobic capacity did not increase significantly (P > 0.10), while VO2max increased from 53 +/- 5 ml.kg-1 min-1 to 58 +/- 3 ml.kg-1.min-1 (P < 0.01) (mean +/- SD). Second, to quantify the effect of high-intensity intermittent training on energy release, seven subjects performed an intermittent training exercise 5 d.wk-1 for 6 wk. The exhaustive intermittent training consisted of seven to eight sets of 20-s exercise at an intensity of about 170% of VO2max with a 10-s rest between each bout. After the training period, VO2max increased by 7 ml.kg-1.min-1, while the anaerobic capacity increased by 28%. In conclusion, this study showed that moderate-intensity aerobic training that improves the maximal aerobic power does not change anaerobic capacity and that adequate high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly, probably through imposing intensive stimuli on both systems.

Greater Age-Related Reductions in Central Arterial Compliance in Resistance-Trained Men

Reductions in the compliance of central arteries exert a number of adverse effects on systemic cardiovascular function and disease risk. Using the cross-sectional study design, we determined the relation between chronic resistance training and carotid arterial compliance. A total of 62 healthy normotensive men, 20 to 39 years of age (young) and 40 to 60 years of age (middle-aged), who were either sedentary or resistance-trained, were studied. In both activity groups, carotid arterial compliance (simultaneous ultrasound and applanation tonometry) was lower ( P P P r =−0.35; P

A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials

Objective:It has been suggested that exercise has preferential effects on visceral fat reduction. However, the dose–response effect remains unclear because of limited evidence from individual studies. The purpose of this study was to systematically review the current literature to establish whether reduction of visceral fat by aerobic exercise has a dose–response relationship.Methods:A database search was performed (PubMed, 1966–2006) with appropriate keywords to identify studies exploring the effects of aerobic exercise as a weight loss intervention on visceral fat reduction. Visceral fat reduction was expressed as the percentage of visceral fat change per week (%ΔVF/w). The energy expenditure by aerobic exercise was expressed as ∑(metabolic equivalents × h per week (METs·h/w)).Results:Nine randomized control trials and seven non-randomized control trials were selected. In most of the studies, the subjects performed aerobic exercise generating 10 METs·h/w or more. Among all the selected groups (582 subjects), visceral fat decreased significantly (P<0.05) in 17 groups during the intervention, but not in the other 4 groups. There was no significant relationship between METs·h/w from aerobic exercise and %ΔVF/w in all the selected groups. However, when subjects with metabolic-related disorders were not included (425 subjects), METs·h/w from aerobic exercise had a significant relationship with %ΔVF/w (r=−0.75). Moreover, visceral fat reduction was significantly related to weight reduction during aerobic exercise intervention, although a significant visceral fat reduction may occur without significant weight loss.Conclusion:These results suggest that at least 10 METs·h/w in aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage, is required for visceral fat reduction, and that there is a dose–response relationship between aerobic exercise and visceral fat reduction in obese subjects without metabolic-related disorders.

Effects of endurance training on resting and post-exercise cardiac autonomic control

PURPOSE Endurance training induces reductions in both resting and postexercise heart rate (HR). If adaptation in cardiac autonomic regulation is a contributing factor in these reductions, changes in cardiac autonomic nervous system (ANS) should correspond to those in HR during an endurance-training program. We investigated the changes in resting and postexercise HR variabilities (both in the time and frequency domain) over a 6-wk training program. METHODS HR variability was measured five times in an endurance-training group (N = 7) and four times in a control group (N = 5) during the course of study. RESULTS Endurance training decreased HR and increased indices of parasympathetic modulation measured both at rest and during postexercise recovery periods. Noteworthy is that no changes in either HR or indices of ANS modulation measured during postexercise recovery periods were detectable after the first 7 d of the study despite continued changes in resting HR and indices in ANS modulation measured between the 7th and 42nd days of the endurance-training program. CONCLUSIONS The study demonstrates that with endurance-training changes in cardiac ANS modulation partly contribute to a decrease in HR at rest and during postexercise recovery period, and that adaptation of the cardiac autonomic control occurs sooner in immediate postexercise periods than at rest.

METs in Adults While Playing Active Video Games: A Metabolic Chamber Study

PURPOSE Active video game systems controlled through arm gestures and motions (Nintendo Wii Sports) and video games controlled through force plate (Wii Fit Plus) are becoming increasingly popular. This study was performed to determine the energy expenditure (EE) during Wii Fit Plus and Wii Sports game activities. METHODS Twelve adult men and women performed all the activities of Wii Sports (five activities: golf, bowling, tennis, baseball, and boxing) and Wii Fit Plus (63 activities classified as yoga, resistance, balance, and aerobic exercises). Each activity was continued for at least 8 min to obtain a steady-state EE. Because EE was assessed in an open-circuit indirect metabolic chamber consisting of an airtight room (20,000 or 15,000 L), subjects were freed of apparatus to collect expired gas while playing the games. MET value was calculated from resting EE and steady-state EE during activity. RESULTS The mean MET values of all 68 activities were distributed over a wide range from 1.3 METs (Lotus Focus) to 5.6 METs (single-arm stand). The mean MET values in yoga, balance, resistance, and aerobic exercise of Wii Fit Plus and Wii Sports were 2.1, 2.0, 3.2, 3.4, and 3.0 METs, respectively. Forty-six activities (67%) were classified as light intensity (<3 METs), and 22 activities (33%) were classified as moderate intensity (3.0-6.0 METs). There were no vigorous-intensity activities (>6.0 METs). CONCLUSIONS Time spent playing one-third of the activities supplied by motion- and gesture-controlled video games can count toward the daily amount of exercise required according to the guidelines provided by the American College of Sports Medicine and the American Heart Association, which focus on 30 min of moderate-intensity daily physical activity 5 d x wk(-1).

Resistance training and arterial compliance: keeping the benefits while minimizing the stiffening.

Objectives This study aimed to determine the effects of moderate resistance training as well as the combined resistance and aerobic training intervention on carotid arterial compliance. Background Resistance training has become a popular mode of exercise, but intense weight training is shown to stiffen carotid arteries. Methods Thirty-nine young healthy men were assigned either to the moderate-intensity resistance training (MODE), the combined resistance training and endurance training (COMBO) or the sedentary control (CONTROL) groups. Participants in the training groups underwent three training sessions per week for 4 months followed by four additional months of detraining. Results All training groups increased maximal strength in all the muscle groups tested (P < 0.05). Carotid arterial compliance (via simultaneous carotid ultrasound and applanation tonometry) decreased approximately 20% after MODE training (from 0.20 ± 0.01 to 0.16 ± 0.01 mm2/mmHg, P < 0.01). No significant changes in carotid arterial compliance were observed in the COMBO (0.20 ± 0.01 to 0.23 ± 0.01 mm2/mmHg) and CONTROL (0.20 ± 0.01 to 0.20 ± 0.01 mm2/mmHg) groups. Following the detraining period, carotid arterial compliance returned to the baseline level. Peripheral (femoral) artery compliance did not change in any groups. Conclusions We concluded that simultaneously performed aerobic exercise training could prevent the stiffening of carotid arteries caused by resistance training in young healthy men.

Longer Time Spent in Light Physical Activity Is Associated With Reduced Arterial Stiffness in Older Adults

Habitual moderate-to-vigorous–intensity physical activity attenuates arterial stiffening. However, it is unclear whether light physical activity also attenuates arterial stiffening. It is also unclear whether light physical activity has the same effects in fit and unfit individuals. This cross-sectional study was performed to determine the relationships between amount of light physical activity determined with a triaxial accelerometer and arterial stiffness. A total of 538 healthy men and women participated in this study. Subjects in each age category were divided into either high-light or low-light physical activity groups based on daily time spent in light physical activity. Arterial stiffness was measured by carotid-femoral pulse wave velocity. Two-way ANOVA indicated a significant interaction between age and time spent in light physical activity in determining carotid-femoral pulse wave velocity (P<0.05). In the older group, carotid femoral pulse wave velocity was higher in the low-light physical activity level group than in the high-light physical activity level group (945±19 versus 882±16 cm/s; P<0.01). The difference remained significant after normalizing carotid-femoral pulse wave velocity for amounts of moderate and vigorous physical activity. The carotid-femoral pulse wave velocity (r=−0.47; P<0.01) was correlated with daily time spent in light physical activity in older unfit subjects. No relationship was observed in older fit subjects. These results suggested that longer time spent in light physical activity is associated with attenuation of arterial stiffening, especially in unfit older people.

Effects of resistance training on arterial stiffness: a meta-analysis

Background Regular aerobic exercise prevents and reverses arterial stiffening, but the association between resistance training and arterial stiffness is unclear. Aim This study was performed to conduct a systematic review and meta-analysis of randomised controlled clinical trials (RCTs) assessing the associations between resistance training and changes in arterial stiffness. Methods MEDLINE and SPORTDiscus databases were searched from January 1980 through to April 2011. RCTs evaluating the ability of resistance training to increase arterial stiffness in comparison with a control group were included in the meta-analysis. Two independent reviewers extracted data and assessed the quality of the included studies. Data from 185 reports of eight RCTs (193 participants) were included. Pooled mean differences in arterial stiffness indices (carotid arterial β stiffness and pulse wave velocity (PWV)) between intervention and control groups were calculated using a random-effects model. Results The overall association of resistance training versus control with relative changes in carotid β index or PWV (eight studies; 193 participants) was 10.7% (95% CI 3.4% to 18.0%; I2, 89%; heterogeneity, p<0.001). Five studies indicated that resistance training in young subjects (n=115) was significantly associated with an increase in stiffness index of 14.3% (95% CI 8.5% to 20.1%; I2, 71%; heterogeneity, p<0.001) compared with controls. However, three studies showed that resistance training in middle-aged subjects (n=78) was not associated with changes in arterial stiffness. In addition, although high-intensity resistance training (n=87) was significantly associated with an increase in stiffness of 11.6%, moderate-intensity resistance training (n=106) showed no such association. Conclusion High-intensity resistance training is associated with increased arterial stiffness in young subjects with low baseline levels of arterial stiffness.

Calf circumference as a surrogate marker of muscle mass for diagnosing sarcopenia in Japanese men and women

To examine the relationship between calf circumference and muscle mass, and to evaluate the suitability of calf circumference as a surrogate marker of muscle mass for the diagnosis of sarcopenia among middle‐aged and older Japanese men and women.