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SUMMARY: KITAHARA, A., T. HAMAOKA, N. MURASE, T. HOMMA, Y. KUROSAWA, C. UEDA, T. NAGASAWA, S. ICHIMURA, M. MOTOBE, K. YASHIRO, S. NAKANO, and T. KATSUMURA. Deterioration of Muscle Function after 21-Day Forearm Immobilization. Med. Sci. Sports Exerc., Vol. 35, No. 10, pp. 1697-1702, 2003.PURPOSE Although it is well known that immobilization causes muscle atrophy, most immobilization models have examined lower limbs, and little is known about the forearm. The purpose of this study was to determine whether forearm immobilization produces changes in muscle morphology and function.METHODS Six healthy males (age: 21.5 ± 1.4, mean ± SD) participated in this study. The nondominant arm was immobilized with a cast (CAST) for 21 d, and the dominant arm was measured as the control (CONT). The forearm cross-sectional area (CSA) and circumference were measured as muscle morphology. Maximum grip strength, forearm muscle oxidative capacity, and dynamic grip endurance were measured as muscle function. Magnetic resonance (MR) imaging was used to measure CSA, and 31phosphorus MR spectroscopy was used to measure time constant (Tc) for phosphocreatine (PCr) recovery after submaximal exercise (PCr-Tc). Grip endurance was expressed by the number of handgrip contractions at 30% maximum grip strength load. All measurements were taken before and after the immobilization.RESULTS After the 21-d forearm immobilization, no changes were seen for each measurement in CONT. CSA and the circumference showed no significant changes in CAST. However, maximum grip strength decreased by 18% (P < 0.05), PCr-Tc was prolonged by 45% (P < 0.05), and the grip endurance at the absolute load was reduced by 19% (P < 0.05) for CAST.CONCLUSION In this model, 21-d forearm immobilization caused no significant changes in forearm muscle morphology, but the muscle function showed remarkable deterioration ranging from 18 to 45%. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate whether serum salusin-a level is related to exercise training-induced changes in blood pressure and arterial stiffness in middle-aged and older adults. Methods: Twenty-eight healthy middle-aged and older subjects (67 ± 1 years) were participated in this study. Subjects completed 8-week of aerobic exercise training (60-70% peak oxygen uptake [V02peak] for 45 min, 3 days/week). We measured brachial blood pressure and carotid-femoral pulse wave velocity (cfPWV) as an indicator of arterial stiffness. Results: After the intervention, V02peak and serum salusin-a level were significantly increased, and systolic blood pressure and cfPWV were significantly reduced (P<0.05). Additionally, significantly negative correlations between the training effects of serum salusin-a level and cfPWV (r=-0.580, P<0.05) or systolic blood pressure (r=-0.409, P<0.05) was seen. Discussion: These results suggest that aerobic exercise training-induced changes in serum salusin-a level may be related to the reduction of blood pressure and arterial stiffness in middle-aged and older adults. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopy (NIRS) was initiated in 1977 by Jobsis as a simple, noninvasive method for measuring the presence of oxygen in muscle and other tissues in vivo. This review honoring Jobsis highlights the progress that has been made in developing and adapting NIRS and NIR imaging (NIRI) technologies for evaluating skeletal muscle O2 dynamics and oxidative energy metabolism. Development of NIRS/NIRI technologies has included novel approaches to quantification of the signal, as well as the addition of multiple source detector pairs for imaging. Adaptation of NIRS technology has focused on the validity and reliability of NIRS measurements. NIRS measurements have been extended to resting, ischemic, localized exercise, and whole body exercise conditions. In addition, NIRS technology has been applied to the study of a number of chronic health conditions, including patients with chronic heart failure, peripheral vascular disease, chronic obstructive pulmonary disease, varying muscle diseases, spinal cord injury, and renal failure. As NIRS technology continues to evolve, the study of skeletal muscle function with NIRS first illuminated by Jobsis continues to be bright. [ABSTRACT FROM AUTHOR]

Adiponectin regulates endothelial nitric oxide synthase in endothelial cells, and body fat loss by aerobic exercise training promotes adiponectin secretion. Recently, C1q/tumor necrosis factor-related proteins (CTRPs) have been identified as novel adipokines and are paralogs of adiponectin, but the association between exercise training-induced reduction of arterial stiffness and circulating CTRPs levels remains unclear. This study aimed to clarify whether the reduction of arterial stiffness in middle-aged and older adults is associated with the change in serum levels of CTRPs induced by exercise training. A total of 52 middle-aged and older participants were randomly divided into two groups: a training group ( n = 26) and a sedentary control group ( n = 26). Participants in the training group completed 8 wk of aerobic exercise training (60-70% peak oxygen uptake for 45 min, 3 days/wk). The reduction of percent whole body fat, abdominal visceral fat area, and carotid-femoral pulse-wave velocity (cfPWV) was significantly greater in the training group than in the control group ( P < 0.05). Moreover, the increase in serum adiponectin, CTRP3, and CTRP5 from baseline to 8 wk was significantly higher in the training group compared with the control group ( P < 0.05). Additionally, the training-induced change in cfPWV was negatively correlated with the training-induced change in serum adiponectin, CTRP3, and CTRP5 levels ( r = -0.51, r = -0.48, r = -0.42, respectively, P < 0.05), and increased plasma nitrite/nitrate level by exercise training was correlated only with adiponectin levels ( r = 0.41, P < 0.05). These results suggest that the exercise training-induced increase in serum CTRPs levels may be associated with the reduction of arterial stiffness in middle-aged and older adults. [ABSTRACT FROM AUTHOR]

Introduction: We examined effects of high-intensity training on chemically induced aberrant crypt foci (ACF) in rat colon. We also investigated mechanisms that may underlie the results obtained, with a focus on secreted protein acidic and rich in cysteine (SPARC), which has been proposed as an exercise-related factor of colon cancer prevention. Methods: After an administration of 1,2-dimethylhydrazine, F344 rats executed high-intensity intermittent swimming training (HIIST) (twelve 20-s swimming with a weight [16% body weight] with 10-s pauses between the bouts) 5 d•wk-1 for 4 wk. The acute and chronic effects of the HIIST on SPARC were evaluated in rats. We evaluated the in vitro and in vivo effects of 5' AMP-activated protein kinase (AMPK) activator on SPARC in rat serum and epitrochlearis muscle. In human subjects, we determined serum SPARC after exhaustive bicycling consisting of six to seven bouts of exercise at 170% ...O2max with 10-s rests between the bouts (high-intensity intermittent bicycling [HIIB]). The SPARC mRNA in human vastus lateralis was measured before and after the HIIB for 4 d•wk-1 for 6 wk (HIIB-training [HIIBT]). Results: The numbers of ACF were lower in the HIIST (47 ± 22) compared with the control (122 ± 47) rats (P < 0.05). SPARC in epitrochlearis and serum after HIIS of the trained rat was higher than that in the control resting rats. In vitro and vivo AMPK stimulation increased mRNA and SPARC protein in rat epitrochlearis, respectively. The human serum SPARC after the HIIB was elevated. SPARC mRNA in human muscle was elevated after the HIIBT. Conclusions: The results demonstrated that HIIST inhibits 1,2-dimethylhydrazine-induced colon ACF development. This effect may be explained by SPARC induction by the exercise intensity-related factor AMPK, potentially explaining the preventive effects of high-intensity intermittent exercise training against colon cancer. [ABSTRACT FROM AUTHOR]

Purpose: The effect of exercise volume represented by exercise intensity and duration on postexercise executive function (EF) improvement remains unclear. In the present study, involving two volume-controlled evaluations, we aimed to compare acute exercise protocols with differing intensities and durations to establish an effective exercise protocol for improving EF. Methods: In study 1, 12 healthy male subjects performed cycle ergometer exercise, based on a low-intensity (LI) protocol for 20 min (LI20), moderate-intensity (MI) protocol for 20 min (MI20), and MI20 volume-matched LI protocol for 40 min (LI40). The exercise intensities for the LI and MI were set at 30% and 60% of peak oxygen consumption, respectively. In study 2, 15 healthy male subjects performed MI exercise for 10 min (MI10), MI20, and 40 min (MI40). To evaluate the EF, the color-word Stroop task was administrated before exercise, immediately after exercise, and during the 30-min postexercise recovery. Results: In study 1, postexercise EF improvement was sustained for a longer duration after MI20 than after LI40 and was sustained for a longer duration after LI40 than after LI20. In study 2, although there was no significant difference in post-MI exercise EF improvement, the magnitude of difference in the EF between preexercise and 30-min postexercise recovery period was moderately larger in MI40, but not in MI40 and MI20, indicating that the EF improvement during postexercise recovery could be sustained after MI40. Conclusion: The present findings showed that postexercise EF improvement could be prolonged after MI exercise with a moderate duration compared with volume-matched LI exercise with a longer duration. In addition, MI exercise with a relatively long duration may slightly prolong the postexercise EF improvement. [ABSTRACT FROM AUTHOR]

Influence of different load exercise to muscle activity during subsequent exercise with 75% of one repetition maximum (RM) load among trained and untrained individuals was verified. Resistance-trained men who were involved in resistance training (n = 16) and healthy young men who did not exercise regularly (n = 16) were recruited for this study. Each subject performed bench pressing with a narrow grip exercise using two different training set methods, the drop-set (DS) (3 sets x 2-10 repetitions with 95-75% of 1RM) and the reverse drop-set (RDS) (3 sets x 3-10 repetitions with 55-75% of 1RM). The mean concentric contraction power, root mean square (RMS) of electromyogra-phy (EMG), area under the oxygenated hemoglobin (Oxy-Hb) curve, and time constant for muscle oxygen consumption (TcVO2mus) values of the triceps brachii were measured during and after the DS and RDS. The trained group demonstrated significantly higher mean muscle power (242.9 ± 39.6 W vs. 215.8 ± 31.7 W), RMS of EMG (86.4 ± 10.4 % vs. 68.3 ± 9.6 %), and area under the Oxy-Hb curve (38.6 ± 7.4 % • sec vs. 29.3 ± 5.8 % • sec) values during the DS than during the RDS (p < 0.05). However, in the untrained group none of the parameters differed significantly for both the DS and RDS. Furthermore, a negative correlation was detected between the area under the Oxy-Hb curve and muscle thickness (r = -0.51, p < 0.01). Long-term effects of DS on muscle strengthening and hypertrophy will be explored in further research. [ABSTRACT FROM AUTHOR]

Objective: Habitual stretching exercise increases carotid arterial compliance, and acute stretching exercise increases arterial compliance in patients with myocardial infarction. However, it is not known whether this arterial adaptation is sustained after exercise. The aim of this study was to examine the effect of a single bout of stretching exercise on the time course of systemic, central, and peripheral arterial stiffness in healthy young subjects. Design: Twenty-six healthy young men performed static stretching exercise involving the entire body (trunk, upper limb, and lower limb) for 40 mins. Pulse-wave velocity (PWV; an index of arterial stiffness), blood pressure, and heart rate were measured before and 0, 15, 30, and 60 mins after stretching exercise. Results: Femoral-ankle PWV and brachial-ankle PWV were reduced relative to baseline 15 and 30 mins after acute stretching (P < 0.05); however, these arterial responses were not sustained for longer periods, and both PWV values returned to the baseline levels within 60 mins. By contrast, carotid-femoral PWV was unchanged. Conclusion: These results suggest that chronic and sufficient repetition of muscle stretch stimulation may result in chronic high arterial compliance, although a single bout of stretch exercise acutely affects arterial compliance. [ABSTRACT FROM AUTHOR]

18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDGPET/ CT) is widely used as a standard method for evaluating human brown adipose tissue (BAT), a recognized therapeutic target of obesity. However, a longitudinal BAT study using FDG-PET/CT is lacking owing to limitations of the method. Near-infrared time-resolved spectroscopy (NIRTRS) is a technique for evaluating human BAT density noninvasively. This study aimed to test whether NIRTRS could detect changes in BAT density during or after long-term intervention. First, using FDG-PET/CT, we confirmed a significant increase (+48.8%, P < 0.05) in BAT activity in the supraclavicular region after 6-week treatment with thermogenic capsaicin analogs, capsinoids. Next, 20 volunteers were administered either capsinoids or placebo daily for 8 weeks in a double-blind design, and BAT density was measured using NIRTRS every 2 weeks during the 8-week treatment period and an 8-week period after stopping treatment. Consistent with FDG-PET/CT results, NIRTRS successfully detected an increase in BAT density during the 8-week treatment (+46.4%, P < 0.05), and a decrease in the 8-week follow-up period (−12.5%, P = 0.07), only in the capsinoid-treated, but not the placebo, group. Thus, NIRTRS can be applied for quantitative assessment of BAT in longitudinal intervention studies in humans. [ABSTRACT FROM AUTHOR]

Large variability exists in muscle adaptive response to resistance exercise (RE) training between individuals. Recent studies have revealed a significant role for microRNAs (miRNAs) in skeletal muscle plasticity. In this study, we investigated how RE affects miRNA expression and whether the variability of muscle hypertrophy to RE training may be attributed to differential miRNA regulation in the skeletal muscle. To screen high and low responders to RE, we had 18 young men perform arm curl exercise training. After screening, all the men performed 12 wk of lower body RE training, but only the high or low responders participated in the acute RE test before training. Muscle biopsies were obtained from the vastus lateralis muscle at baseline, 3 h after acute RE, and after the training period. Total RNA was extracted from the skeletal muscle, and miRNA expression (800 miRNAs) was analyzed. RE training increased the cross-sectional area of the biceps brachii (-1.7-26.1%), quadriceps (2.2-16.8%), and hamstrings (1.6 -18.4%). Eighty-five and 102 miRNAs were differentially expressed after acute and chronic RE, respectively (P < 0.05). Seventeen miRNAs, especially 23b-3p, 26a-5p, 32-5p, 148b-3p, and 376a-3p, were differentially expressed at baseline, and 23 miRNAs, especially let-7a-5p, 95, 148a-3p, and 376a-3p, and 26 miRNAs, especially 30d-5p and 376a-3p, were differentially regulated after acute and chronic RE, respectively, in the skeletal muscle between high and low responders, indicating that the expression patterns of several miRNAs are altered by acute or chronic RE, and that miRNAs are involved in skeletal muscle adaptation to RE training. [ABSTRACT FROM AUTHOR]

Aging-induced arterial stiffening is reduced by aerobic exercise training, and elevated production of nitric oxide (NO) participates in this effect. Adropin is a regulator of endothelial NO synthase and NO release, and circulating adropin level decreases with age. However, the effect of habitual aerobic exercise on circulating adropin levels in healthy middleaged and older adults remains unclear. We sought to determine whether serum adropin level is associated with exercise training-induced changes in arterial stiffness. First, in a cross-sectional study, we investigated the association between serum adropin level and both arterial stiffness and cardiorespiratory fitness in 80 healthy middle-aged and older subjects (65.6 ± 0.9 yr). Second, in an intervention study, we examined the effects of 8-wk aerobic exercise training on serum adropin level and arterial stiffness in 40 healthy middle-aged and older subjects (67.3 ± 1.0 yr) divided into two groups: aerobic exercise training and sedentary controls. In the cross-sectional study, serum adropin level was negatively correlated with carotid β-stiffness (r = - 0.437, P < 0.001) and positively correlated with plasma NOx level (r = 0.493, P < 0.001) and cardiorespiratory fitness (r = 0.457, P < 0.001). Serum adropin levels were elevated after the 8-wk aerobic exercise training intervention, and training-induced changes in serum adropin level were correlated with traininginduced changes in carotid β-stiffness (r = - 0.399, P < 0.05) and plasma NOx level (r = 0.623, P < 0.001). Thus the increase in adropin may participate in the exercise-induced reduction of arterial stiffness. [ABSTRACT FROM AUTHOR]

Aging-induced elevation in C1q secretion activates the Wnt signaling pathway in muscles, leading to the development of muscle fibrosis. However, the association between serum C1q level and muscle mass and strength remains unclear in humans. The aim of the study was to elucidate whether serum C1q level is associated with aging- and resistance training-induced changes in muscle mass and strength. First, in a cross-sectional study, we investigated the association between serum C1q level and muscle mass and strength in 131 healthy subjects, aged 20-81 yr. Second, in an intervention study, we examined the association between the effects of serumC1q level and muscle mass and strength on 12wk resistance training in 11 healthy older adults (60-81 yr). In the cross-sectional study, serum C1q level increased with aging and was negatively correlated with muscle mass and strength. Furthermore, 12 wk resistance training in older adults reduced the ageassociated elevation in serum C1q levels. The training effect of serum C1q level significantly correlated with the change in the cross-sectional area of the thigh (r =20.703; P < 0.01). Serum C1q level may reflect loss ofmusclemass; therefore, C1qmay be a novel biomarker of sarcopenia. [ABSTRACT FROM AUTHOR]

Skeletal muscle can synthesize testosterone and 5a-dihydrotestosterone (DHT) from dehydroepiandrosterone (DHEA) via steroidogenic enzymes in vitro, but hormone levels and steroidogenic enzyme expression decline with aging. Resistance exercise has been shown to increase in plasma sex steroid hormone levels. However, it remains unclear whether resistance training can restore impaired steroidogenic enzyme expressions in older individuals. Six young and 13 older men were recruited, and muscle biopsies were taken from the vastus lateralis at basal state. The same group of older subjects underwent resistance training involving knee extension and flexion exercises for 12 wk, and post-training biopsies were performed 4 - 5 d after the last exercise session. Muscular sex steroid hormone levels and sex steroidgenesis-related enzyme expressions were significanfly lower in older subjects than younger ones at baseline, but 12 wk of resistance training significantly restored hormone levels (DHEA: 432±26 at baseline, 682±31 pg/μg protein, DHT: 6.2±0.9 at baseline, 9.8±1.4 pg/fJ-g protein). Furthermore, the steroidogenesis-related enzymes such as 3ßhydroxysteroid dehydrogenase (HSD), 17ß-HSD, and 5a-reductase expressions were significantly restored by resistance training. We conclude progressive resistance training restores age-related declines in sex steroidogenic enzyme and muscle sex steroid hormone levels in older men.--Sato, K., Iemitsu, M., Matsutani, K., Kurihara, T., Hamaoka, T., Fujita, S. Resistance training restores muscle sex steroid hormone steroidogenesis in older men. [ABSTRACT FROM AUTHOR]

PURPOSE: 1) To examine the effects of an 8-hour constant sitting on physiological parameters comprehensively in healthy males and 2) To validate the effects of elastic garments on blunted blood flow and muscle oxygenation. METHODS: Nine healthy males (age; 22.6 ± 1.4 years old, BMI; 22.4 ± 1.8, %body fat; 15.2 ± 5.7%) completed an 8-hour constant sitting. Following the baseline measurement, each subject was randomized to wear lower-pressure (15 hPa on average in the ankle) elastic garment either a right leg or a left leg from the inguinal region through to the ankle joint. Circumferences in the calf and malleolus, blood flow of dorsal metatarsal, the concentrations of oxygenated hemoglobin ([oxy-Hb]), deoxygenated Hb ([deoxy-Hb]), and total Hb [total-Hb] and tissue oxygen saturation, in the lateral head of gastrocnemius muscles were measured using near infrared time resolved spectroscopy before, during, and after the 8-hour constant sitting in the bilateral extremities. Extracellular water content in the lower extremities measured by bioelectrical impedance analysis were also assessed before and after the 8-hour constant sitting as a marker of edema. RESULTS: The circumference was significantly enlarged during the 8-hour constant sitting (2.4 ± 0.7% for the calf and 2.7 ± 1.4% for the malleolus at 8 hours compared with baseline values, p < 0.05, respectively). The [oxy-Hb], [total-Hb], and tissue oxygen saturation in the lateral head of gastrocnemius muscles was consistently lower in the control legs than the legs with elastic garment with the 8-hour of sitting. The blood flow of the dorsal metatarsal artery fell significantly during the 8-hour constant sitting (61.4 ± 16.2% at 8 hours, p < 0.01). Further, after the 8- hour constant sitting, the changes in extracellular water content in lower extremity muscles had positive correlations with the changes in the calf circumference. Whereas, wearing elastic garments resulted in reduction of circumference enlargement, tissue oxygenation decline, and fall of blood flow during the 8-hour constant sitting. CONCLUSIONS: The 8-hour constant sitting induced leg edema, and deteriorated blood flow and tissue oxygenation in the lower extremity. Conversely application of the elastic garment,, successfully protected the deterioration of these physiological changes. [ABSTRACT FROM AUTHOR]