Effect of moderate exercise training on T-helper cell subpopulations in elderly people

CD28 molecule expression on the surface of T cells plays a critical role in upregulation of various cytokines synthesis and T-helper (Th) cell proliferation and differentiation. However aging induces a decrease in CD28 expression and unbalance of Th1/Th2, leading to impairment of Th-cell mediated immune function. The purpose of this study was to assess the effects of moderate exercise training on CD28 expression and the balance of Th1/Th2 cells in elderly people. Forty-eight elderly subjects were assigned to an exercise training group (EXC: 13 males, 15 females; aged 61-76) or a non-exercise control group (CON: 7 males, 13 females; aged 62-79). Subjects in EXC participated in exercise sessions 5-days a week for 6 months. Meanwhile, subjects in CON maintained their normal physical activity levels during the study period. Blood samples were collected before and after the training period. Samples were measured for the number of leukocytes and lymphocytes, as well as for CD3+, CD4+, CD28+CD4+, IFN-gamma+CD4+, IL-4+CD4+ cells. The number of leukocytes, lymphocytes, and CD3+ cells did not change after 6 months in both EXC and CON. The number of CD4+ and CD28+CD4+ cells significantly increased after the training in EXC (P < 0.05), while CON did not show significant changes. In the EXC group, IFN-gamma+CD4+ cell numbers were significantly higher following the training (P < 0.05), but the number of IL-4+CD4+ cells was not changed. In the CON group, there were no significant alterations in IFN-gamma+CD4+ and IL-4+CD4+ cell numbers. In conclusion, moderate exercise training in the elderly is associated with improvement of expression of CD28 on Th cells and Th1/Th2 balances. Therefore, exercise training could up-regulate Th cell-mediated immune functions and be helpful for a decrease in the risk of infections and autoimmune diseases in elderly people.

Influence of adiponectin gene polymorphism SNP276 (G/T) on adiponectin in response to exercise training

Adiponectin is an adipocytokine that is involved in insulin sensitivity. The adiponectin gene contains a single nucleotide polymorphism (SNP) at position 276 (G/T). The GG genotype of SNP276 (G/T) is associated with lower plasma adiponectin levels and a higher insulin resistance index. Therefore, we examined the influence of SNP276 (G/T) on the plasma level of adiponectin in response to exercise training. Thirty healthy Japanese (M12/F18; 56 to 79 years old) performed both resistance and endurance training, 5 times a week for 6 months. The work rate per kg of weight at double-product break-point (DPBP) was measured. Blood samples were obtained before and after the experiment. Plasma concentrations of adiponectin, HbA1c, insulin, glucose, total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol, and triglyceride were measured. Genotypes of SNP276 were specified. Student's t-test for paired values and unpaired values was used. After the 6-month training period, the work rate per kg of weight at DPBP and the plasma HDL-cholesterol level were significantly improved (P<0.05), while no change was observed in the total plasma adiponectin level. However, the plasma adiponectin level in those with the GT + TT genotype had significantly increased (P<0.05). Additionally, the degree of the decrease in the HOMA-R level was significantly greater in the subjects with the GT + TT genotype than those with the GG genotype (p<0.05). Our results suggest that subjects with the genotype GT + TT at SNP276 (G/T) have a greater adiponectin-related response to exercise training than those with the GG genotype.

Thigh muscle activation distribution and pulmonary V̇o2 kinetics during moderate, heavy, and very heavy intensity cycling exercise in humans

The mechanisms underlying the oxygen uptake (V̇o2) slow component during supra-lactate threshold (supra-LT) exercise are poorly understood. Evidence suggests that the V̇o2 slow component may be caused by progressive muscle recruitment during exercise. We therefore examined whether leg muscle activation patterns [from the transverse relaxation time (T2) of magnetic resonance images] were associated with supra-LT V̇o2 kinetic parameters. Eleven subjects performed 6-min cycle ergometry at moderate (80% LT), heavy (70% between LT and critical power; CP), and very heavy (7% above CP) intensities with breath-by-breath pulmonary V̇o2 measurement. T2 in 10 leg muscles was evaluated at rest and after 3 and 6 min of exercise. During moderate exercise, nine muscles achieved a steady-state T2 by 3 min; only in the vastus medialis did T2 increase further after 6 min. During heavy exercise, T2 in the entire vastus group increased between minutes 3 and 6, and additional increases in T2 were seen in adductor magnus and gracilis during this period of very heavy exercise. The V̇o2 slow component increased with increasing exercise intensity (being functionally zero during moderate exercise). The distribution of T2 was more diverse as supra-LT exercise progressed: T2 variance (ms) increased from 3.6 ± 0.2 to 6.5 ± 1.7 between 3 and 6 min of heavy exercise and from 5.5 ± 0.8 to 12.3 ± 5.4 in very heavy exercise (rest = 3.1 ± 0.6). The T2 distribution was significantly correlated with the magnitude of the V̇o2 slow component ( P < 0.05). These data are consistent with the notion that the V̇o2 slow component is an expression of progressive muscle recruitment during supra-LT exercise.

Ultrastructure of Human Placental Tissue After 6h of Normoxic and Hypoxic Dual In Vitro Placental Perfusion

The dual in vitro perfusion model of human placental tissue allows the study of different aspects of placental function, such as metabolism, transport and secretion of proteohormones, cytokines and prostaglandins. The integrity of the perfused placental tissue is an important parameter to validate the perfusion system. Using light and electron microscopy, the morphology of villous tissue was examined before and after six hours of normoxic (n=10) vs. hypoxic (n=10) perfusion. An apical shift of the rough endoplasmic reticulum and occasional vacuoles were found in the syncytiotrophoblast of the terminal villi, the exchange area of the placenta. No unexpected pathological findings were seen before the perfusion experiments and only slight changes with moderate distension of the endoplasmic reticulum after 6 h of normoxic perfusion. After hypoxic perfusions, distinct ultrastructural alterations, such as oedematous villous stroma, swollen or completely destroyed cell organelles (e.g., mitochondria and endoplasmic reticulum), multiple vacuoles inside syncytio- and cytotrophoblasts as well as the microvilli were seen, which leads to an impairment of the placental barrier and other functions. The ultrastructural examination of placental tissue before and after dual in vitro perfusion broadens the knowledge of physiological and pathophysiological processes in the perfused placenta and may be a beneficial part of regular validation.

Sex differences in the relationship between estrogen receptor alpha gene polymorphisms and arterial stiffness in older humans

BACKGROUND

Increased arterial stiffness is an independent risk factor for cardiovascular disease. The estrogen system (estrogen and estrogen receptor-alpha [ER-alpha]) has potent vasodilator and antiatherosclerotic activity in vascular tissue and therefore was implicated in the regulation of arterial stiffness. We hypothesized that the relationship between arterial stiffness and gene polymorphisms in ER-alpha has a sex-specific component in older humans.

METHODS

Two hundred healthy older subjects, comprised of 85 men and 115 postmenopausal women (men, 66 +/- 5 years old; women, 64 +/- 7 years old; mean +/- SD) participated in a cross-sectional study. We determined the genotypes of single-nucleotide polymorphisms (SNPs) at -401T/C of intron 1 and at 30T/C of exon 1 of ER-alpha, using a TaqMan-polymerase chain reaction method. Arterial stiffness was estimated by brachial-ankle pulse-wave velocity (baPWV).

RESULTS

Polymorphisms of both -401T/C and 30T/C in ER-alpha affected baPWV values in postmenopausal women but did not affect men. The baPWV in women was significantly lower in the CC genotype at both -401T/C and 30T/C than in the TT genotype (both P < .05), and the CC genotype of two SNPs in women was significantly lower than in men.

CONCLUSIONS

The present study suggests that the relationship between arterial stiffness and -401T/C or 30T/C polymorphisms in ER-alpha is different between sexes in older humans. These polymorphisms may be important in the health and clinical care of cardiovascular function and disease in older women.

Effect of Free-Living Daily Physical Activity on Salivary Secretory IgA in Elderly

PURPOSE

The aim of this work was to assess the relationship in elderly subjects between free-living daily physical activity and mucosal immunity, especially salivary secretory immunoglobulin A (SIgA).

METHODS

Elderly volunteers (114 men and 170 women) aged 71.3 +/- 0.3 yr (range: 65-86 yr) participated in this study. Resting saliva samples were collected in the morning. Saliva samples stimulated by chewing a sterile cotton ball at a frequency of 60/60 s were collected. The SIgA concentration was measured using enzyme-linked immunosorbent assay (ELISA), and the SIgA secretion rate was calculated. Free-living step count (steps per day), energy expenditure (kJ x kg(-1) x d(-1)), and activity durations (min x d(-1)) at specific intensity levels (inactive, light, moderate, and vigorous) were evaluated using an electric pedometer. The data obtained were stratified by pedometer-determined steps per day using quartiles (Q1-Q4) for distribution.

RESULTS

Elderly in quartiles showed step counts of 2962 +/- 94, 5118 +/- 62, 6832 +/- 59, and 9951 +/- 264 steps per day. Significant differences were found in the mean step count (P<0.0001), energy expenditure (P<0.0001), and activity duration (P<0.0001) with increasing pedometer-determined activity quartiles. Both SIgA concentration and SIgA-secretion rate were significantly higher for Q3 than for Q1 (P<0.05). Meanwhile, saliva flow rates showed no significant differences across quartiles.

CONCLUSION

These results suggest that a free-living daily physical activity level of approximately 7000 steps per day might be regarded as a moderate daily physical activity target for elderly people to improve mucosal immune function.

Age-related reduction of systemic arterial compliance relates to decreased aerobic capacity during sub-maximal exercise

A decrease in systemic arterial compliance (SAC) increases left ventricular load along with the demand for excessive myocardial oxygen consumption when the age-related reduction of SAC reaches a marked level, and consequently may depress left ventricular pump function. Reduced left ventricular pump function decreases aerobic capacity, and some study groups have shown that SAC and/or central arterial distensibility is correlated with maximal aerobic capacity in humans. We thus hypothesize that, once the age-related reduction of SAC reaches a marked level, the participation of SAC in aerobic capacity will be significant even during sub-maximal exercise. Thirty young humans and 46 elderly humans participated in this study. SAC, oxygen uptake at the ventilatory threshold (VO2VT), and the ratio of increase in oxygen uptake, in cardiac output, and in effective arterial elastance to increase in work rate (deltaVO2/deltaWR, deltaCO/deltaWR and deltaEa/deltaWR) were measured. SAC was significantly higher in young subjects compared with elderly subjects, and was significantly related to VO2VT in elderly subjects. SAC also significantly correlated with deltaVO2/deltaWR, deltaCO/deltaWR and deltaEa/deltaWR in elderly subjects. When total subjects were divided by the value of SAC into 6 groups, the VO2VT values in the 3 groups with lower SAC were significantly lower than those in the 3 groups with higher SAC, and gradually decreased with the reduction of SAC. There were no changes in VO2VT among the 3 groups with higher SAC. These results suggest that the participation of SAC in aerobic capacity is significant even during sub-maximal exercise in individuals who show a pronounced age-related reduction of SAC.

Effects of exercise, age and gender on salivary secretory immunoglobulin A in elderly individuals

The influence of age and gender on salivary secretory immunoglobulin A (SIgA) in response to moderate exercise training was studied in 158 elderly subjects. Subjects were assigned to an exercise training group (EXC: 51 males, 74 females) or a non-exercise control group (CON: 11 males, 22 females). The subjects in each group were separated into four age-gender subgroups (60-69-yr-old males, over 70-yr-old males, 60-69-yr-old females, over 70-yr-old females) and compared by age and gender. Subjects in EXC participated in exercise sessions 5-days a week for 6 months. Saliva samples were collected both before and after the study period. The SIgA secretion rates were significantly increased after training (p < 0.05) in all the age-gender subgroups of EXC (60-69 males: 41%, over 70 males: 55%, 60-69 females: 40%, over 70 females: 38%); no age- or gender-related differences were observed. On the other hand, none of the age-gender subgroups of CON showed significant changes in the SIgA secretion rate; also, there were no age- or gender-related differences. In conclusion, enhancement of mucosal immune function following regular moderate exercise training occurs in elderlies in their 60s and over 70 years, and in both, males and females.

Even low-intensity and low-volume exercise training may improve insulin resistance in the elderly

OBJECTIVE

Moderate to high intensity exercise training is known to ameliorate the coronary risk factors in relation to an improvement in body composition. However, the benefit of low-intensity and low-volume training for these risk factors remains unclear in elderly people. Therefore, we investigated the effects of low-intensity and low-volume exercise training on blood lipid values and insulin resistance in the elderly.

METHODS

A total of 56 healthy elderly individuals (42 females and 14 males) aged 64+/-6 years participated in a 12-week exercise program, comprising aerobic training and resistance training.

RESULTS

After the program, there were no significant changes in high-density lipoprotein cholesterol, triglyceride serum levels, or in peak oxygen uptake on average. However, the homeostasis of minimal assessment of insulin resistance (HOMA-IR) value was significantly reduced by 21%. The participants were categorized into tertiles based on initial Body Mass Index (BMI). The Middle-BMI group (non-obese subjects) showed reduced HOMA-IR (2.0-->1.3, P<0.01), but this reduction was not associated with the reduction in BMI (r=0.08, P=0.74), whereas the two reductions were significantly associated in the High-BMI group (r=0.61, P=0.01).

CONCLUSION

Even low-intensity and low-volume exercise training, which would ordinarily be insufficient for improving mean lipid values or aerobic fitness, was found to be effective in improving insulin resistance in the elderly. The improvement in insulin resistance was independent of the improvement in obesity.

Effects of leg resistance training on arterial function in older men

BACKGROUND

Little information is available on the effect of strength training on vascular function, particularly in older people.

OBJECTIVE

To determine the effect of resistance training on arterial stiffness and endothelial function in older adults.

METHOD

Eleven healthy men (mean (SEM) age 64 (1) years) performed 12 weeks of resistance training involving knee flexion and extension (three sets a day, two days a week).

RESULTS

Resistance training increased maximal muscle power by 16% (p<0.0001). Arterial stiffness as assessed by aortic pulse wave velocity did not change with resistance training. Plasma concentration of nitric oxide (NO), measured as its stable end product (nitrite/nitrate), had increased (p<0.05) after resistance training (61.2 (10.4) v 39.6 (3.2) micromol/l). There was no change in plasma concentration of endothelin-1.

CONCLUSION

The results suggest that short term resistance training may increase NO production without stiffening central arteries in healthy older men.

Effects of short-term endurance training on aortic distensibility in young males

BACKGROUND

Short-term endurance exercise training can increase aortic distensibility. The effect of exercise on arterial distensibility, however, may not last long term.

PURPOSE

We evaluated the effects of short-term exercise training and detraining on aortic distensibility in 10 sedentary young males (21.0 +/- 0.6 yr, mean +/- SE; range 19-24 yr).

METHODS

The subjects underwent 8 wk of endurance training on a cycle ergometer at 70% of maximal oxygen consumption (VO(2max)), for 60 min at a time and on alternate days (3-4 d.wk(-1). The detraining period consisted of a return to sedentary days for 8 wk. The aortic pulse wave velocity (APWV) was measured before and immediately after training and during the detraining period.

RESULTS

The VO(2max) was significantly increased after training (pre: 2240.0 +/- 71.4 mL, after: 2728.8 +/- 82.5 mL, mean +/- SE, P < 0.0001) and remained at increased levels during the detraining period (after 4 wk: 2671.2 +/- 73.6 mL, P < 0.001; after 8 wk: 2628.0 +/- 85.0 mL, P < 0.001). The APWV was significantly decreased after training (pre: 5.80 +/- 0.15 m.s(-1), after: 5.50 +/- 0.21 m.s(-1), P < 0.01) but returned close to the baseline after detraining for 4 wk (5.66 +/- 0.13 m.s, P < 0.18).

CONCLUSION

Our data suggest that short-term exercise training can improve aortic distensibility, but the effect cannot be maintained without continuing physical exercise.

Polymorphism in Endothelin-Related Genes Limits Exercise-Induced Decreases in Arterial Stiffness in Older Subjects

Increase in arterial stiffness is associated with aging, which is improved by regular exercise. Endothelin (ET) system has crucial roles in regulating vascular tone and in the progression of atherosclerosis. We hypothesized that molecular variations (ie, gene polymorphisms) in ET-related gene might affect exercise-induced improvement in arterial stiffness with age in human subjects. The present study provides a cross-sectional investigation of 191 healthy middle-aged and older (65±1 years) human subjects to clarify the relationship between the regular exercise-induced improvement of arterial stiffness and the gene polymorphisms of ET converting enzyme (ECE)-1, ECE-2, ET-A receptor (ET-A), and ET-B receptor (ET-B). The study subjects were divided into active and inactive groups based on the median value (186 kcal/d) of energy expenditure. Brachial-ankle arterial pulse wave velocity (baPWV) was used to evaluate arterial stiffness. All individuals were genotyped for 4 different polymorphisms of the ET system: 2013(+289)A/G in intron 17 of ECE-1, 669(+17)T/C in intron 5 of ECE-2, 958A/G in exon 6 of ET-A, and 831A/G in exon 4 of ET-B. The baseline baPWV was significantly lower in the active group without any change in blood pressure. Polymorphisms in ECE-1 influenced basal blood pressure. Polymorphisms in ECE-1 and ECE-2 had no effect on baPWV between active and inactive groups. However, polymorphisms in both ET-A and ET-B affected baPWV in the 2 groups. The present results suggest that differences in ET-A and ET-B polymorphisms may influence the response of the vascular wall to exercise whereas ECE-1 polymorphisms may affect basal blood pressure.

A 2-year follow-up study on muscle size and dynamic strength in teenage tennis players

Growth trends in the cross-sectional area of the quadriceps femoris (CSA(QF)) and its dynamic strength in 12 teenage tennis players (six boys and six girls), aged from 10.7 to 13.2 years at the onset of the study, were investigated through a 2-year follow-up survey. CSA(QF) values at the three levels (proximal, mid, and distal to the knee joint) and dynamic torques during knee extensions at three pre-set velocities (1.05, 3.14, and 5.24 rad/s) were determined year by year, i.e., three times (T1, T2, and T3), using magnetic resonance imaging and an isokinetic dynamometer, respectively. In both genders, the CSA(QF) values at the three levels tended to increase across the measurement times, with greater gains in the boys than in the girls at the levels mid and distal to the knee joint. Among these changes, only the CSA(QF) at the level proximal to the knee joint significantly increased regardless of changes in both skeletal age and body height. The ratios of torque to the sum of CSA(QF) at the three levels (T/CSA) at 3.14 and 5.24 rad/s for the boys and at 5.24 rad/s for the girls were significantly higher in T2 and T3 than T1. Further, the relative increases in torque and T/CSA values at 3.14 and 5.24 rad/s were greater in the boys than the girls. The findings presented here indicate that young tennis players who are in the earlier stage of adolescence increase the CSA of the QF muscle beyond normally expected growth change at the level proximal to the knee joint and show a predominant development in torque generation capability during high-velocity knee extensions, with a greater gain in boys compared with girls.

Effect of spontaneous exercise on antioxidant capacity in rat muscles determined by electron spin resonance

AIMS

The effect of physical activity on antioxidant capacity in muscle remains unknown. This study investigated the effect of spontaneous exercise on antioxidant capacity in rat muscles determined by electron spin resonance (ESR), which is a technique for the direct detection of free radicals.

METHODS

Ten-week-old male Wistar rats were housed individually in cages with a running wheel. Rats were classified as high activity (HA), middle activity (MA) or low activity group (LA), based on an assessment of running distance covered over a 23-week period. After 23 weeks of housing, soleus (Sol), plantaris (Pl), gastrocnemius [deep/surface portions (GasD/GasS)] and heart (Hrt) muscles were isolated, and scavenging activity against superoxide anions (O(2)(*-)) and hydroxyl radicals (HO(*)) was determined by ESR using a spin-trap chemical. The citrate synthase (CS) activity was used as a marker of mitochondrial oxidative phosphorylation capacity.

RESULTS

Among the parameters measured, only O(2)(*-) scavenging activity in GasD significantly correlated with the running distance. The highest scavenging activity was observed in Hrt of HA rats. The O(2)(*-) scavenging activity in Pl of MA rats was significantly higher than that of LA rats. The O(2)(*-) scavenging activity of Sol and GasS was not significantly different between the three groups. Furthermore, the HO(*) scavenging activity of any muscle specimens was similar among the three groups and did not correlate with running distance at all. CS activity did not significantly differ between the three groups.

CONCLUSION

These data suggest that O(2)(*-) scavenging activity in specific types of muscle tissues would increase especially in spontaneously active animals. However, HO(*) scavenging activity would not.

Age-Related Reduction of Systemic Arterial Compliance Induces Excessive Myocardial Oxygen Consumption during Sub-Maximal Exercise

Reduction of systemic arterial compliance (SAC) with aging increases left ventricular afterload. The present study was designed to examine whether age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise. We studied elderly (60-69 years; n = 25) and senior (70-82 years; n = 25) subjects. We measured SAC immediately before the start of the ramp-fashion exercise (i.e., at the end of the 20 W warm-up exercise) and the double product (DP: systolic blood pressure x heart rate) during the ramp-fashion exercise (20-50 W). SAC was significantly lower in senior subjects (0.76 +/- 0.25 ml mmHg(-1) m(-2)) compared with elderly subjects (0.95 +/- 0.22 ml mmHg(-1) m(-2)). DP was higher in senior subjects (20 W: 14.3 +/- 3.1; 30 W: 15.9 +/- 4.2; 40 W: 17.7 +/- 4.9; 50 W: 20.6 +/- 5.6 [x 10(3) mmHg bpm]) than in elderly subjects (12.8 +/- 3.0, 14.0 +/- 3.5, 15.1 +/- 4.0, 17.1 +/- 4.3 [x 10(3) mmHg bpm]). In total subjects, SAC correlated significantly with DP (r = -0.64, r = -0.64, r = -0.64, r = -0.64). In senior subjects, SAC was related significantly to DP (r = -0.83, r = -0.78, r = -0.76, r = -0.74). In elderly subjects, SAC tended to correlate with DP although its relationships were not statistically significant (r = -0.34, r = -0.36, r = -0.33, r = -0.31). Correlation coefficients at each respective exercise intensity were significantly higher in senior subjects compared with elderly subjects. These results suggest that the age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise in older humans, but this relation does not become significant until the SAC reduction becomes pronounced.

Aortic Stiffness and Aerobic Exercise: Mechanistic Insight from Microarray Analyses

INTRODUCTION/PURPOSE

Regular aerobic exercise reduces aortic stiffness. However, the mechanisms by which chronic exercise lowers arterial stiffness are not known. To determine the molecular mechanisms of these changes, the alteration of gene expression in the aorta by aerobic exercise training was measured with the microarray technique.

METHODS/RESULTS

The differences in expression levels of 3800 genes in the abdominal aorta of sedentary control rats (8 wk old) and exercise-trained rats (8 wk old, treadmill running for 4 wk) were compared by the microarray analysis. Aortic pulse wave velocity (PWV) was lower and systemic arterial compliance was higher (both P < 0.05) in the exercise-trained group than in the control group. Of the 323 genes that displayed differential expression (upregulation of 206 genes and downregulation of 117 genes), a total of 29 genes (24 upregulated and 5 downregulated genes) were identified as potential candidate genes that may be involved in vasodilation and arterial destiffening. Using real-time quantitative polymerase chain reaction, we confirmed the results of microarray analysis that prostaglandin EP2 receptor (PGE-EP2R), prostaglandin EP4 receptor (PGE-EP4R), C-type natriuretic peptide (CNP), and endothelial nitric oxide synthase (eNOS) genes were differentially expressed. Furthermore, there were modest correlations between arterial stiffness and levels of these factors. Differential expression of eNOS gene was further verified at protein level by using Western blot analysis.

CONCLUSION

These results suggest that exercise training induces the altered expression in several genes including prostaglandin, CNP, and nitric oxide in the aorta and that these molecular changes (particularly eNOS as its protein expression was altered) may contribute, at least in part, to the beneficial effect of exercise training on aortic stiffness.

Recruitment of the thigh muscles during sprint cycling by muscle functional magnetic resonance imaging

The purpose of the present study was to investigate recruitment patterns of the thigh muscles during maximal sprint cycling by muscle functional magnetic resonance imaging (mfMRI). Twelve healthy men participated in this study and performed 2, 5, and 10 sets of 6-s supramaximal cycling with a load of 7.5 % of their body weight with 0.5 min of rest between the sets. Before and immediately after the exercise, T2-weighted MR images, i.e. mfMRI, of the right-thigh were taken to calculate T2 of eleven thigh muscles. Vastus lateralis, semitendinosus, and sartorius were the highest activated, i. e. had the greatest T2 change, among the quadriceps, hamstring, and adductors, respectively, compared with other muscles. Total power output during 2, 5, and 10 sets of sprint cycling was correlated with percent change in T2 in the quadriceps correlated (r (2) = 0.507 to 0.696, p < 0.01), the hamstring (r (2) = 0.162 to 0.335, p < 0.05 approximately 0.001), and the adductor muscles (r (2) = 0.162 to 0.473, p < 0.05 approximately 0.0001). With use of stepwise regression analysis, total power output was significantly correlated with % change in T2 of the vastus medialis (VM) (p < 0.0001) and vastus intermedius (VI) (p < 0.05) (r (2) = 0.698, p < 0.0001). We concluded that eleven thigh muscles were activated non-uniformly, and that the VM and VI play a key role during maximal sprint cycling.

Moderate regular exercise increases basal production of nitric oxide in elderly women

Vascular endothelial cells produce nitric oxide (NO), which is a potent vasodilator substance and is thought to have antiatherosclerotic properties. Therefore, it has also been proposed that NO may be useful to regulate vascular tonus and prevent progression of atherosclerosis. On the other hand, NO activity reduces with aging. We previously reported that the plasma nitrite/nitrate (NOx: the stable end product of NO) concentration was significantly increased by intense aerobic exercise training in healthy young humans. We hypothesized that lifestyle modification (e.g., even mild regular exercise training) can increase NO production in previously sedentary older humans. We measured the plasma NOx concentration before and after a mild aerobic exercise training regimen (cycling on a leg ergometer at 80% ventilatory threshold for 30 min, 5 days/week) for 3 months in elderly women. In addition, we assessed the plasma concentration of cyclic guanosine monophosphate (cGMP), a second messenger of NO, in the same samples. The individual ventilatory threshold increased significantly after the 3-month exercise training. The blood pressure at rest significantly decreased after exercise training. These results suggest that the 3-month exercise training in the older women produced favorable physiological effects. The plasma concentration of NOx significantly increased by the exercise training, and the plasma concentration of cGMP also increased by the exercise training. The present study suggests that even a mild regular aerobic-endurance exercise increases NO production in previously sedentary older humans, which may have beneficial effects (i.e., antihypertensive and antiatherosclerotic effects by endogenous NO) on the cardiovascular system.