Watanabe K, Ichinose M, Tahara R, Nishiyasu T. Individual differences in cardiac and vascular components of the pressor response to isometric handgrip exercise in humans. Am J Physiol Heart Circ Physiol 306: H251-H260, 2014. First published November 8, 2013 doi:10.1152/ajpheart.00699.2013.-We tested the hypotheses that, in humans, changes in cardiac output (CO) and total peripheral vascular resistance (TPR) occurring in response to isometric handgrip exercise vary considerably among individuals and that those individual differences are related to differences in muscle metaboreflex and arterial baroreflex function. Thirty-nine healthy subjects performed a 1-min isometric handgrip exercise at 50% of maximal voluntary contraction. This was followed by a 4-min postexercise muscle ischemia (PEMI) period to selectively maintain activation of the muscle metaboreflex. All subjects showed increases in arterial pressure during exercise. Interindividual coefficients of variation (CVs) for the changes in CO and TPR between rest and exercise periods (CO: 95.1% and TPR: 87.8%) were more than twofold greater than CVs for changes in mean arterial pressure (39.7%). There was a negative correlation between CO and TPR responses during exercise (r ϭ Ϫ0.751, P Ͻ 0.01), but these CO and TPR responses correlated positively with the corresponding responses during PEMI (r ϭ 0.568 and 0.512, respectively, P Ͻ 0.01). The CO response during exercise did not correlate with PEMI-induced changes in an index of cardiac parasympathetic tone and cardiac baroreflex sensitivity. These findings demonstrate that the changes in CO and TPR that occur in response to isometric handgrip exercise vary considerably among individuals and that the two responses have an inverse relationship. They also suggest that individual differences in components of the pressor response are attributable in part to variations in muscle metaboreflex-mediated cardioaccelerator and vasoconstrictor responses. cardiac output; peripheral vascular resistance; muscle metaboreflex; arterial baroreflex DURING ISOMETRIC EXERCISE, arterial blood pressure, heart rate (HR), and sympathetic nerve activity all increase in association with increases in the intensity and duration of the exercise. This pressor response is governed mainly by neural mechanisms: central command (52) as well as a feedback system operating via afferent input from exercising skeletal muscle receptors (muscle metaboreflex and mechanoreflex) (40,41,51) and from arterial and cardiopulmonary baroreceptors (arterial and cardiopulmonary baroreflexes) (51, 52). While the increase in arterial pressure during isometric exercise is a well-established response, the responses of the components mediating the pressor response, cardiac output (CO) and total peripheral vascular resistance (TPR), remain controversial. In fact, previous studies have shown that, during isometric handgrip exercise in healthy humans, the pressor response occurs via an increase in CO (16,32,[34][35][36]57), an increase in TPR (6, 17), or both of those...
BackgroundHigh-intensity exercise affects the level of salivary nitric oxide (NO) with an impact on oxidative stress such as a reactive nitrogen-oxide species. However, in athletes with high-intensity training, the relationship between salivary NO levels and oxidative stress is yet to be clear. Additionally, the association of salivary NO levels and the common health disorders of athletes is unknown. Thus, the aim of this cross-sectional study was to clarify the relationship between salivary NO levels and oxidative stress, and the health/medical disorders existing in elite class university athletes.MethodsIn 250 athletes (males, 151 and females, 99) from undergraduate levels of Japanese University, we investigated the relationship between levels of salivary NO and oxidative stress markers: derived reactive oxygen species (d-ROMs) and biological antioxidant potential (BAP), and also examined that whether salivary NO levels are associated with diseases.ResultsThere were no significant association between the levels of salivary NO and oxidative stress markers (such as d-ROM and BAP). From the questionnaire, asthma was the most prevalent as evident from medical history of the athletes. Additionally, the salivary NO levels were higher (520 ± 43 µmol/L vs. 375 ± 13 µmol/L, P < 0.05) in the asthma group (n = 9) than in the non-asthma group (n = 241). We determined the optimal cut-off value (P = 0.019) of the salivary NO levels for asthma was 425 µmol/L, with a sensitivity of 88.9% and specificity of 61.8% (area under the curve (AUC), 0.73).ConclusionsOur results suggest that the high levels of salivary NO in trained university athletes in Japan may potentially predict asthma. And this salivary NO level is not associated with markers of oxidative stress and existing diseases in athletes studied here.
The hypothesis of this research was that elderly people with many remaining teeth and good occlusion (8020 achievers) would be able to maintain proper head and body posture, despite aging. The purpose of this study, as a first stage, was to clarify the aging phenomenon of cervical curvature in 8020 achievers in comparison with that in young adults.Subjects consisted of twenty-eight 8020 achievers, with a mean age of 3.3ע69.28 years and 0.4ע5.62 teeth. For comparison, forty adults in their 20's with a mean age of 7.0ע9.22 years and 6.0ע2.82 teeth were also enrolled. The cervical vertebra was assessed based on the distance from the CV line (tangential line of the 2nd and 6th cervical vertebra) to each cervical vertebra and the angles formed by the cervical and reference lines in the cranial bone.Every distance from the CV line to each cervical vertebra in the 8020 group was bigger than that in the 20's group (pϽ0.01-0.001). The distance from the CV line to CV-3 and CV-5 in 8020 women was larger than that in 8020 men (pϽ0.05). Every distance from the CV line to each cervical vertebra in 8020 women was larger than that in 20's women (pϽ0.01-0.001). There was no significant difference between 8020 men and 20's men. The difference between the women's group was more marked than that between age groups for men.The cervical curvature in 8020 achievers showed a greater tendency toward cervical lordosis than that in young adults. In the 8020 achievers, the curvature in women was greater than that in men. The curvature in 8020 women seemed was marked, showing strong cervical lordosis, despite the presence of many remaining teeth and good occlusion. It remains to be determined by comparing 8020 achievers with ordinary elderly whether the condition of the teeth influences spinal curvature with aging.
The aim of this study was to test the hypotheses that, in humans, cardiac output (CO) and total peripheral vascular resistance (TPR) responses to isometric exercise vary among individuals, and that the individual differences are related to the muscle metaboreflex and the arterial baroreflex functions. Healthy subjects (n = 32) performed 1‐min isometric handgrip exercise (HG) at 50% of maximal voluntary contraction, followed by a 4‐min period of post‐exercise muscle ischemia (PEMI) to selectively maintain activation of the muscle metaboreflex. In 11 subjects the pressor response to HG occurred solely by the increase in CO, but in 18 subjects it occurred due to both the increases in CO and TPR, and further it occurred solely via the increase in TPR in 3 subjects. Thus the pressor components varied widely among subjects. The CO and TPR responses during HG were positively correlated with those responses during PEMI, respectively. In addition, the CO response to PEMI was negatively correlated with the PEMI‐induced changes in an index of cardiac vagal tone and cardiac baroreflex sensitivity. We conclude that CO and TPR responses to HG vary among individuals, and that the individual differences in components of the pressor response could be attributed in part to the variations in the muscle metaboreflex and the arterial baroreflex functions. This study was supported by the grants from Japan Society for the Promotion of Science.
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