Anton Ušaj

The endurance training effect on the oxygenation status of an isometrically contracted forearm muscle.

Abstract The aim of the study was to find the influence of training on the oxygenation status of a forearm muscle during submaximal isometric contraction. Six subjects performed a test of isometric contraction of a forearm muscle by continuous pressing of a handgrip dynamometer with a force of 15 kp, until exhaustion. The continuous measurements of oxygen saturation (%) (OXY), concentration of oxygenated haemoglobin (μM) (OXYHb), deoxygenated haemoglobin (μM) (DEOXYHb) and total haemoglobin (μM) (TOTHb) in blood, which passed through the muscle, were made by the near infrared spectroscope Oxymeter 96208 (ISS, USA). This test was repeated before and after the four weeks training period, which consisted of 5 continuous isometric contractions of 30 s at the beginning and of 1:15 min during the last week. Training did not significantly influence maximal isometric force (55.5 ± 10 kp before, 60.2 ± 9 kp after). On the other hand, the duration of isometric contraction increased from 271 ± 117 s to 388 ± 152 s (P < 0.05). Subjects were substantially different in duration of muscle contraction and also in oxygenation status during the contractions. Therefore, the relationship between these parameters and the training effect was calculated. The training effect was represented as the difference between the duration of muscle contraction before and after the training period. This parameter significantly correlated with relative oxygen saturation (r=-0.88; P < 0.05) and with relative concentration of deoxygenated haemoglobin (r = 0.87; P < 0.05). These results demonstrated the importance of individual training adaptations of forearm muscles. The increase of the duration of submaximal isometric contraction, as a training effect, can be dependent on larger muscle deoxygenation.

The oxygen uptake threshold during incremental exercise test

Abstract The linear relationship between oxygen consumption (Vo2) and exercise intensity is a well established phenomenon observed during incremental exercise. Recently, a non-linear increase in Vo2 has been reported by Zoladz et al., who used a relatively complicated method to describe the phenomenon. In this study, we tried to ascertain whether the same phenomenon, which we named the oxygen uptake threshold (OUT), could be described by a simple method, using the two best fitting lines adopted for the less and more steep parts of the Vo2 increase. Our hypothesis was that the non-linear Vo2 increase was the result of a continuous Vo2 increase (oxygen drift) occurring during the more intense steps only. Therefore, we analysed the Vo2 time course during each step. Six cyclists performed an incremental exercise test on a cyclo - ergometer. The lactate threshold (LT) was calculated by using the intersection point of the two best fitting lines in the diagram of log LA (lactate concentration) dependence on log P (Power). The time course of Vo2 during each step was analysed by an exponential rise to the maximum model. The results showed that OUT could be determined in five of the six subjects, whereas LT could be determined in all six subjects. The power output determined by OUT (168 ± 13 W) was similar to that determined by LT (180 ± 25 W). The Vo2 time course during each step showed steady values during low intensity exercise. At intensities above LT and OUT, however, Vo2 increased continuously, showing oxygen drift. It may be concluded that OUT is a realistic phenomenon, which is based on oxygen drift.

The increase of duration of isometric contraction may not relate to change of relative oxygenation of forearm muscle

The aim of this study is to ascertain, how an increase in duration of isometric contraction influences tissue oxygenation of forearm muscles, undergoing physical training. Four subjects underwent 6 weeks of training of the left forearm muscles by performing isometric contractions. Subjects repeated 10 s contractions, 10–15 times in the first, and 20 s contractions in the second 3 week period. Relative oxygenation of forearm muscles was measured by using Near Infrared Spectroscopy (CWS2000, NIM Incorporated, Philadelphia). The training increased the duration of isometric contraction at 20 kp of experimental forearm muscles by 41 ± 25 s, which was more (P < 0.05) than in control forearm (8 ± 4 s). This increase was not reflected in changes of maximum relative deoxygenation of experimental muscles, which decreased by only —6.9 ± 14.4 %. The results show that an increase in duration of isometric contraction may not depend on the oxygenation of muscle tissue at fixed force of 20 kp.

Changes in blood pH, lactate concentration and pulmonary ventilation during incremental testing protocol on cycle ergometer

Abstract We investigated mutual changes in the blood lactate concentration ([LA]), blood pH and pulmonary ventilation (VE) to obtain insight into the regulation of pH at different levels of the exercise intensity. For this purpose the ratio VE/[LA] (l/min/mmol/l) was determined at each particular pH corresponding to exercise intensity in seven healthy subjects on the cycle ergometer during incremental exercise test. Changes in VE/[LA] ratio were found to exhibit three phases. In the first phase, the ratio increased without significant changes in [LA] and pH until it reached certain individual peak value. In the second phase, VE/[LA] decreased because increases in [LA] were considerably bigger than those of VE. Decreases in blood pH followed those of VE/[LA], nevertheless differences existed among subjects depending on how successful individual subjects regulated their blood pH. In the third phase with the VE/[LA] values stabilized between 15 and 22 and pH values between 7.32 and 7.26, whereas differences between subjects became negligible. Similar trends to VE/[LA] were observed in case of the Onset of Blood Lactate Accumulation (OBLA) throughout the test at pH values below 7.32, as was manifested by the correlation coefficient. We conclude that blood pH regulation due to respiratory compensation of the lactate acidosis is more successful in subjects with better endurance (higher OBLA), but only when [LA] is slightly increased or at slight acidosis.

The Influence of High-Altitude Acclimatization on Ventilatory and Blood Oxygen Saturation Responses During Normoxic and Hypoxic Testing

Abstract We investigated how acclimatization effects achieved during a high-altitude alpinist expedition influence endurance performance, ventilation (V˙E

The Influence of Reduced Breathing During Incremental Bicycle Exercise on Some Ventilatory and Gas Exchange Parameters

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Cardiorespiratory Responses of Adults and Children during Normoxic and Hypoxic Exercise

) and blood oxygen saturation (SaO2) in normoxic (NOR) and hypoxic conditions (HYP). An incremental testing protocol on a cycle ergometer was used to determine the power output corresponding to the Lactate (PLT) and Ventilatory Threshold (PVT) in NOR and HYP (FiO2=0.13) as indirect characteristics of endurance performance in both conditions. Furthermore, changes in V˙E

The Influence of Endurance Training on Brain and Leg Blood Volumes Translocation During an Orthostatic Test

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The influence of strength-endurance training on the oxygenation of isometrically contracted forearm muscles

, SaO2, blood pH and Pco2 were measured at a similar absolute exercise intensity of 180 W in NOR and HYP conditions. Seven experienced alpinists (mean ± SD: age: 50 ± 6 yrs; body mass: 76 ± 5 kg; body height: 175 ± 8 cm) volunteered to participate in this study after they had reached the summit of Gasherbrum II and Ama Dablam. They had therefore experienced the limitations of their acclimatization. Individual differences of PLT between values reached after and before the expedition (∆PLT) correlated (r = 0.98, p = 0.01) with differences of SaO2 (∆SaO2) in HYP, and differences of PVT (∆PVT) correlated (r = -0.83, p = 0.02) with differences of V˙E(ΔV˙E)

Can Blood Gas and Acid-Base Parameters at Maximal 200 Meters Front Crawl Swimming be Different Between Former Competitive and Recreational Swimmers?

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