European journal of applied physiology
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Eur. J. Appl. Physiol. · Jul 2010
Application of bioreactance for cardiac output assessment during exercise in healthy individuals.
In patients with cardiac failure, bioreactance-based cardiac output (CO) monitoring provides a valid non-invasive method for assessing cardiac performance during exercise. The purpose of this study was to evaluate the efficacy of this technique during strenuous exercise in healthy, trained individuals. Fourteen recreational cyclists, mean (SD) age of 34 (8) years and relative peak oxygen uptake of (VO(2)) 56 (6) ml kg(-1) min(-1), underwent incremental maximal exercise testing, whilst CO was recorded continuously using a novel bioreactance-based device (CO(bio)). ⋯ Likewise, calculated (C(a - v) O(2)) was greater when determined using CO(bio) than CO(rb) (P < 0.001), although both devices provided values in excess of those reported in invasive studies. Bioreactance-based determination of CO provides a pragmatic approach to the continuous assessment of cardiac performance during strenuous exercise in trained individuals. Our findings, however, suggest that further work is needed to refine the key measurement determinants of CO using this device to improve measurement accuracy in this setting.
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Eur. J. Appl. Physiol. · Jun 2010
Muscle performance during isokinetic concentric and eccentric abduction in subjects with subacromial impingement syndrome.
Peak torque (PT), total work (TW) and acceleration time (AT) were measured during isokinetic concentric and eccentric abduction of the shoulder in subjects with subacromial impingement syndrome (SIS) and healthy subjects. The SIS group consisted of 27 subjects (33.48 +/- 9.94 years) with unilateral SIS and it was divided into two groups: (1) SIS with the dominant involved side, (2) SIS with the nondominant involved side. The control group consisted of 23 healthy subjects (32.26 +/- 9.04 years). ⋯ At 180 degrees /s, the nondominant uninvolved side of the SIS group demonstrated slower AT (P < 0.05) compared to the dominant side of the control group, as well as the nondominant involved side of the SIS group compared to the nondominant side of the controls. The results showed no alterations in the measured parameters during concentric and eccentric phases of isokinetic abduction in subjects with SIS when compared to a control group. However, alterations may be observed in the contralateral side during the eccentric phase of abduction in subjects with unilateral conditions of SIS.
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Eur. J. Appl. Physiol. · May 2010
Low vagal tone is associated with impaired post stress recovery of cardiovascular, endocrine, and immune markers.
Reduced heart rate variability (HRV) and delayed blood pressure recovery are associated with increased cardiovascular risk. Besides this evident link, the vagus is thought to play an inhibitory role in the regulation of other allostatic systems, including inflammation and the hypothalamic-pituitary-adrenal (HPA) axis. However, human evidence is scarce. ⋯ Confirming our hypothesis, low vagal tone was associated with impaired recovery of cardiovascular, endocrine, and immune markers in healthy males. The data support an inhibitory role of the vagus in the regulation of allostatic systems as described in the neurovisceral integration model. We posit reduced resting HRV as a risk marker for future cardiovascular and other stress-related disease.
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Eur. J. Appl. Physiol. · Mar 2010
Controlled Clinical TrialEffect of lecturing to 200 students on heart rate variability and alpha-amylase activity.
The aim of this study was to examine cardiovascular [heart rate variability (HRV)] and autonomic nervous system activation (by evaluating salivary alpha-amylase activity) that occur in professors both to, and after, the delivery of a lecture to 200 students and to determine whether gender is an influencing factor upon response. Fifty-two participants (26 women and 26 men) collected eight unstimulated saliva samples on 2 days (one a working day on which the lecture was given, the other a non-work or rest day). They also completed the Trait version of the State-Trait Anxiety Inventory (STAI) to assess their dispositional anxiety on the rest day and the State section of the STAI 15 min before and 10 min after their lecture, repeated at the same hour on the control (rest) day. ⋯ AA activity measured on the teaching day was significantly higher than that noted on the resting day. Lecturing resulted in a significant increase in the secretion of the stress marker alpha-amylase. Men and women did not differ in trait and state anxiety and no gender differences for HRV or AA activity were found.