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Showing papers in "European Journal of Applied Physiology in 1975"


Journal ArticleDOI
TL;DR: The findings of an enhanced glycolysis during exercise in the heat is compatible with earlier studies which demonstrate a decreased availability of oxygen due to a reduction in muscle blood flow.
Abstract: In an effort to assess the effects of environmental heat stress on muscle metabolism during exercise, 6 men performed work in the heat (Tdb = 44 degrees C, RH = 15%) and cold (Tdb = 9 degrees C, RH = 55%). Exercise consisted of three 15-min cycling bouts at 70 to 85% VO2max, with 10-min rest between each. Muscle biopsies obtained from the vastus lateralis before and after each work bout were analyzed for glycogen and triglyceride content. Venous blood samples drawn before and after exercise were assayed for lactate, glucose, free fatty acids, hemoglobin, and hematocrit. Oxygen uptake, heart rates and rectal temperatures were all significantly higher during exercise in the heat. Blood lactate concentration was roughly twice as great during the heat experiments as that measured in the 9 degrees C environment. Muscle glycogen utilization per 60 min was significantly greater in the heat ( - 74 m moles/kg-wet muscle) as compared to the cold exercise (- 42 m moles/kg-wet muscle). On the average, muscle triglyceride declined 23% during exercise in the cold and 11% in the heat. The findings of an enhanced glycolysis during exercise in the heat is compatible with earlier studies which demonstrate a decreased availability of oxygen due to a reduction in muscle blood flow.

205 citations


Journal ArticleDOI
TL;DR: Experiments with artificial ischaemia of the upper arm together with MBF measurements showed that MBF was of no importance for continuing sustained contractions above a certain force level, however, the level where longer lasting (>15 min) sustained contraction is possible is directly related to MBF.
Abstract: The endurance during sustained contraction of elbow, flexors, elbow extensors, and back extensors was tested in 3 human subjects. The force level used was varied between ca. 15 and ca. 75% of maximal isometric strength (IS). The clearance of133Xe from contracting muscles was registered during and after the endurance test. In this way it was possible to determine whether muscle blood flow (MBF) was increased or had stopped during the contraction. Experiments with artificial ischaemia of the upper arm together with MBF measurements showed that MBF was of no importance for continuing sustained contractions above a certain force level, which was 50, 25, and 40% of IS for elbow flexors, elbow extensors and back extensors, respectively. However, the level where longer lasting (>15 min) sustained contraction is possible is directly related to MBF. These levels were 22, 15, and 20% IS for elbow flexors, elbow extensors, and back extensors, respectively.

155 citations


Journal ArticleDOI
TL;DR: Altering in adrenalsympathico function were indicated by increased levels of cortisol, epinephrine, and norepinephrine and water and electrolyte balance was not sufficient to maintain body weight, the runners losing approximately 2.8 kg.
Abstract: Adrenal-sympathico function, blood carbohydrates and lipids, and water and electrolyte balance were studied in six highly trained male marathon runners prior to and after running a marathon (26.2 miles; 42.2 km) and on control days corresponding to the above times. Fluid intake was not sufficient to maintain body weight, the runners losing approximately 2.8 kg. Estimated plasma volume losses (161 ml, 4.4%) indicated that most of the fluid loss was extravascular. Tre rose an average 2.4 degrees C and a significant negative correlation between running time and rise in Tre was observed. Glucose, fatty acids, glycerol, hemoglobin, and plasma proteins were significantly elevated after the race. Small but statistically significant increments in lactate and pyruvate were also observed. Alterations in adrenal-sympathico function were indicated by increased levels of cortisol, epinephrine, and norepinephrine.

80 citations


Journal ArticleDOI
TL;DR: Criteria for the identification of maximal steady state as related to state of conditioning were evaluated and the 10 min heart rate associated with a blood lactate level of 2.2 mM/L (MSSHR) was the best predictor of conditioning.
Abstract: Criteria for the identification of maximal steady state as related to state of conditioning were evaluated. 13 volunteers walked and/or ran during a series of 15 min tests on a treadmill. The speeds ranged from mild to exhaustive. Heart rate was monitored continuously; $$\dot V_{O_2 } $$ was determined from 6 min to 9 min; and venous blood was obtained at 10 min and 15 min for lactate analyses. Max $$\dot V_{O_2 } $$ was established for each subject. Subjects were classified on level of conditioning according to the quantity and quality of their activity record for the previous 6 months. The 10 min heart rate associated with a blood lactate level of 2.2 mM/L (MSSHR) was the best predictor of conditioning. The relative $$\dot V_{O_2 } $$ (% of max $$\dot V_{O_2 } $$ ) found with a 10 min blood lactate concentration of 2.2 mM/L (RMSS $$\dot V_{O_2 } $$ ) was almost as accurate as MSSHR in predicting state of conditioning. Changes in blood lactate levels between 10 min and 15 min were not significantly related to conditioning.

62 citations


Journal ArticleDOI
TL;DR: A new method which permits, in a single measurement, the determination of the moment of inertia, the angular damping coefficient of the joint and the location of the centre of mass of a body segmentin situ is presented.
Abstract: A new method which permits, in a single measurement, the determination of the moment of inertia, the angular damping coefficient of the joint and the location of the centre of mass of a body segmentin situ is presented. The underlying principle is the theory of small, damped oscillations of a system about its equilibrium position. The fact that the oscillogram contains information about certain parameters of the oscillating system is used to find these parameters. The application of the method is simple and does not require highly sophisticated instrumentation. The results are very reproducable and immediately available.

62 citations


Journal ArticleDOI
TL;DR: It is proposed to assess anaerobic power by measuring excess CO2, concurrently with determination of max, and ergometric criteria derived on the basis of the tests proposed, may be used for systematization of various physical work loads.
Abstract: The criteria of max $$\dot V_{O_2 } $$ and max O2 D which are traditionally used in studying aerobic and anaerobic work capacity, have the different dimensions. While max $$\dot V_{O_2 } $$ is an index of the power of aerobic energy output, max O2 D assesses the capacity of anaerobic sources. For a comprehensive assessment of physical working capacity of athletes, both aerobic and anaerobic capabilities should be represented in three dimensions,i.e. in indexes of power, capacity and efficiency. Experimental procedures have been developed for assessing these three parameters in treadmill running tests. It is proposed to assess anaerobic power by measuring excess CO2, concurrently with determination of max $$\dot V_{O_2 } $$ . Maximal aerobic capacity is established as the product of max $$\dot V_{O_2 } $$ by the time of max $$\dot V_{O_2 } $$ maintenance determined in a special test with running at critical speed. The ergometric criteria derived on the basis of the tests proposed, may be used for systematization of various physical work loads.

62 citations


Journal ArticleDOI
TL;DR: The results showed that endurance training leads to increased activities of oxidative enzymes in the skeletal muscle, and a possibility exists that the turnover of muscle collagen in endurance athletes is continuously faster than that in sedentary men of corresponding ages.
Abstract: A cross-sectional study was carried out to examine the activities of certain enzymes representing aerobic and anaerobic energy metabolism as well as the biosynthesis of collagen of M. vastus lateralis in 23 male endurance athletes in habitual training, aged 33 to 70 years. 23 sedentary healthy men of corresponding ages were selected for the control group. The mean maximal oxygen uptake of the trained subjects was 53.6 ml · kg−1 · min−1 and that of the control subjects 36.3 ml · kg−1 · min−1. As compared to the control group the trained subjects had significantly higher values in the muscle malate dehydrogenase, succinate dehydrogenase and prolyl hydroxylase activities, whereas the opposite was true in the activity of lactate dehydrogenase. In hexokinase and creatine phosphokinase no marked differences between the groups were observed. The results showed that endurance training leads to increased activities of oxidative enzymes in the skeletal muscle. The adaptation changes were also observed in old men. The increased activity of prolyl hydroxylase may reflect the general enzymatic adaptation to physical training. A possibility exists that the turnover of muscle collagen in endurance athletes is continuously faster than that in sedentary men of corresponding ages.

50 citations


Journal ArticleDOI
TL;DR: Since the large ODC-shift to the right of the trained group was not reproducible underin vitro conditions, it is suggested that a rapidly decaying unknown substance accounts for the remaining difference inPO2.
Abstract: In experiments with graded exercise of 15 men (6 untrained, 3 semitrained, 6 endurance-trained) the trained subjects showed a massive shift to the right of thein vivo O2 dissociation curve (ODC) of femoral venous blood. At a saturation of 20 to 25% (18 mkp/sec)PO2 was about 9 mm Hg higher for the trained than for the untrained group. The following factors play a role: 1. The 2,3-diphosphoglycerate [2,3-DPG] concentration was increased by 15 to 20% in the trained group which explains about 2 mm Hg of the difference inPO2. 2. Exercise acidosis in the femoral venous blood depends to a large extent on CO2 in the trained, but on lactic acid in the untrained group. At low saturations the CO2-Bohr effect increases sharply thus having a greater importance in the trained subjects. This factor can explain about 2 mm Hg of the difference. However, influence of chloride and 2,3-DPG on the Bohr effect must be taken into consideration. 3. Since the large ODC-shift to the right of the trained group was not reproducible underin vitro conditions, it is suggested that a rapidly decaying unknown substance accounts for the remaining difference inPO2.

49 citations


Journal ArticleDOI
H. Löllgen, H V Ulmer1, R. Gross1, G. Wilbert1, G. v. Nieding 
TL;DR: Methodical aspects of the relationship between pedalling rate and rotating mass and perceived exertion rating (PER) were studied in trained, untrained, and ill subjects in bicycle ergometry to determine the strictness of the PER work load relationship.
Abstract: Methodical aspects of the relationship between pedalling rate and rotating mass and perceived exertion rating (PER; Borg, 1962) were studied in trained, untrained, and ill subjects in bicycle ergometry. Pedalling rate varied between 40 and 100 rpm, work load steps were 5, 10, 15 and 20 mkp/sec in the healthy subjects, and 2.5, 5, 7.5 and 10 mkp/sec in the patients. PER decreased with increasing pedalling rate in all healthy subjects. In the patients, PER increased moderately at work load of 2.5 mkp/sec, but decreased at higher work loads up to 80 rpm, followed by a slight increase at 100 rpm. Higher mass of the flywheel, studied in 6 trained subjects, lowered the PER insignificantly. In the healthy subjects, test criteria, such as reproducibility, reliability, sensitivity, and linearity remained almost unaffected by pedalling rate. In patients, increasing pedalling speed diminished reproducibility and sensitivity. The strictness of the PER work load relationship is lowered at higher pedalling rate, especially at 100 rpm. When using the PER scale, pedalling rate has to be considered as an factor of main influence.

43 citations


Journal ArticleDOI
TL;DR: The data of the study suggest that the specific training of paddlers do result in a effect on the haemodynamic adaptations to arm work, and oxygen consumption and ventilation during work with the arms was lower in the group of paddler.
Abstract: Maximal oxygen uptake and circulatory adaptation to work with legs and arms were studied in a group of 5 paddlers members of the Belgian national squad and a control-group of 9 trained subjects. The results showed that the specific armtraining of paddlers induced changes in the arm-to-leg ratio of physiological parameters at submaximal and maximal work. In the group of paddlers maximal oxygen intake and workload during arm-exercise averaged respectively 88.6% and 80.3% of the scores obtained with leg-exercise. In the control group the arm to leg ratio varied between 81.2% and 65.2%. At a submaximal load of 100 W the difference in heartfrequency was 21 beats/min in the canoe group and 35 beats/min in the control group. Oxygen consumption and ventilation during work with the arms was lower in the group of paddlers. The data of our study suggest that the specific training of paddlers do result in a effect on the haemodynamic adaptations to arm work

40 citations


Journal ArticleDOI
TL;DR: Results may suggest the differential fatigue of motor units employed in the three motor tasks, MVC, voluntary reaction and achilles tendon reflex, which is postulate a neurally mediated increase in gain of the stretch servomechanism.
Abstract: Effects of three different fatiguing local muscular exercises upon plantar flexion reaction time and achilles tendon reflex time have been studied in 24 normal males. The Exercise Conditions, each involving a series of 30 maximal voluntary isometric contractions (MVC) of the plantar flexors, differed by allowing either 5, 10 or 20 sec rest interval between each MVC. Decrements in strength ranged from 15% to 34% MVC. Trend analysis of the fatigue patterns revealed that a cubic orthogonal polynomial equation was sufficient to describe the profile of MVC decrement for all conditions (Table 3). Following the fatiguing exercise, simple visual reaction time (plantar flexion), and its two components, premotor and motor time, failed to demonstrate any change from Pre Exercise Conditions. Achilles Tendon Reflex Times, however, demonstrated a marked augmentation, as manifest in reduced total reflex times, contraction times and half relaxation times. These results may suggest the differential fatigue of motor units employed in the three motor tasks,viz. MVC, voluntary reaction and achilles tendon reflex. A plausible explanation for the augmentation of the reflex contraction resides in the known potentiating effect of elevated intramuscular temperature. Alternatively, one might postulate a neurally mediated increase in gain of the stretch servomechanism. The possibility of both mechanisms being operative is not excluded.

Journal ArticleDOI
TL;DR: It is suggested that the benefits of intermittent WU, as used in this study in young children, can be attributed to physiological rather than psychological mechanisms.
Abstract: Twelve boys, 7–9 years old, who, by use of questionnaires, were found to be ignorant of the concept of “warm-up”, performed maximal aerobic and anaerobic tasks 4 min after completing a 15 min intermittent warm-up (WU) (30 sec treadmill run, 30 sec pause). The WU required some 60% of the individual's\(\dot V_{O_2 \max } \), and raised rectal temp. by 0.52±0.19° C. The aerobic criterion task (CT) was a one-stage bicycle ride at a load predetermined to exhaust the subject after 4 min. The anaerobic CT was a 30 sec all-out ride against resistance of 35 gm/kg BW. Subjects also performed both CT's without any WU.\(\dot V_{O_2 \max } \) (aerobic CT), HRmax, as well as total mechanical work output achieved during the aerobic CT, were significantly higher with WU, compared with the non-WU sessions. During the anaerobic CT total revolutions, total power output, as well as peak HR, were significantly higher following WU. It is suggested that the benefits of intermittent WU, as used in this study in young children, can be attributed to physiological rather than psychological mechanisms.

Journal ArticleDOI
TL;DR: The underestimation of MBF calculated from133Xe clearance and the levelling-off shown by this method may be due to a systematic error inherent in the method, the133XE clearance being diffusion limited at high flow rates.
Abstract: 16 male subjects exercised at 25, 50, 75, 90, 100 and 120% of VO2max on a von Dobeln bicycle ergometer. The muscle mass was measured in a whole body counter. Muscle blood flow (MBF) estimated from the rate of 133Xe clearance from m. rectus femoris showed a levelling-off at about 0.5 1 of blood per min and liter of muscle tissue (equal to an irrigation coefficient of 0.5 min-1) at work rates above 50 to 60% of VO2 max. This concurs with clearance data from the literature. However, when MBF is calculated from VO2, muscle mass, and reliable values for a- vo2 differences, MBF in the present subjects would: 1. Not level off before 90 to 100% VO2max, 2. reach a value of 1.0 min-1. The underestimation of MBF calculated from 133Xe clearance and the levelling-off shown by this method may be due to a systematic error inherent in the method, the 133Xe clearance being diffusion limited at high flow rates.

Journal ArticleDOI
TL;DR: Following exercise at 30 rpm, the isometric endurance was 25 to 50% lower than that found at the most advantageous speed of cycling for the authors' subjects; at these faster rates of cycling two subjects showed least static component following exercise at 90 rpm while the remaining subject performed best after cycling at 50 rpm.
Abstract: A new approach has been devised to assess the “static component” of dynamic exercise This technique involves the measurement of the isometric endurance of muscles which have just taken part in rhythmic exercise and depends on the repeatability of trained subjects in isometric effort The premise is that isometric endurance will be inversely related to the static component of the preceding dynamic exercise The subjects worked on a bicycle ergometer at known fractions of their maximal aerobic capacity (max\(\dot V_{O_2 } \)) The rate of pedalling was varied from 30 to 90 rpm, so that for a given % max\(\dot V_{O_2 } \), the belt tension varied inversely with the speed of cycling At any one speed of cycling, isometric endurance decreased as the belt tension increased Following exercise at 30 rpm, the isometric endurance was 25 to 50% lower than that found at the most advantageous speed of cycling for our subjects; at these faster rates of cycling two subjects showed least static component following exercise at 90 rpm while the remaining subject performed best after cycling at 50 rpm

Journal ArticleDOI
TL;DR: Two groups, matched for size and age, showed no significant differences in constant speed, incremental load maximal aerobic capacity, maximum heart rate, or in post-exercise peripheral venous blood concentrations of lactate or pyruvate, however, post-Exercise peripheral Venous blood ammonia levels were significantly higher in the group tested on the bicycle ergometer than in the treadmill group.
Abstract: From a population of 20 healthy male volunteers, half performed constant speed, incremental load maximal aerobic capacity (VO2max) tests on a motor-driven treadmill, while the other half performed similar VO2max tests on a bicycle ergometer. The two groups, matched for size and age, showed no significant differences in VO2max, maximum heart rate, or in post-exercise (4 min ) peripheral venous blood concentrations of lactete or pyruvate. However, post-exercise peripheral venous blood ammonia levels were significantly higher in the group tested on the bicycle ergometer than in the treadmill group.

Journal ArticleDOI
TL;DR: There was a very high correlation between the mean speed calculated from the best performances in competition swims of 400 m and 1500 m and a value which is thought to express the aerobic energy available to the swimmer.
Abstract: The purpose of this study was to consider which characteristics are related to a high velocity in water during swimming. The study was performed on 13 of the best competition swimmers of the region of Lyon (France). The collected data were:\(\dot V_{O_2 } \) max, measured during leg-work (\(\dot V_{O_2 } \) max LW), during arm-work (\(\dot V_{O_2 } \) max AW), and the hydrodynamic resistances measured when the swimmers were towed at the speed of 1.80 m/sec. The cardiac output was measured for four of the subjects. The swimmers were characterized by a mean\(\dot V_{O_2 } \) max LW of 56 ml/kg/min and by a high value of the ratio\(\frac{{\dot V_{O_2 } \max {\text{ }}AW}}{{\dot V_{O_2 } \max {\text{ }}LW}}\) which reached 99% for three of them. There was a very high correlation (r = 0.90 and 0.91) between the mean speed calculated from the best performances in competition swims of 400 m and 1500 m and a value which is thought to express the aerobic energy available to the swimmer: $$\dot V_{O_2 } \max water:\dot V_{O_2 } \max {\text{ }}AW + \frac{{\dot V_{O_2 } \max {\text{ }}LW - \dot V_{O_2 } \max {\text{ }}AW}}{6}$$

Journal ArticleDOI
TL;DR: During the prenatal period a favorable effect of work-load for the offspring could be induced more easily even with mild aerobic and quite short daily exercise than later during postnatal life as shown by experiments reported previously.
Abstract: In two series of experiments the development of body weight, heart weight and the microstructure of the rat heart in the male offspring from exercised and control inactive mothers was followed. In 50-day-old male offspring the total body weight and heart weight did not differ; in 100-day-old male offspring the heart weight was significantly higher in those from mothers exercising daily for 1 hr (run on a tread-mill with the speed 14 to 16 m/min,i.e. mild exercise of an aerobic character) throughout pregnancy. As regards microstructure of the heart, the differences were significant both in younger and older animals. The number of muscle fibers and capillaries per mm2 in the heart was significantly higher in male offspring of exercised mothers. The capillary: fiber ratio was significantly higher and the diffusion distance significantly shorter in male offspring of exercised mothers. During the prenatal period a favorable effect of work-load for the offspring could be induced more easily even with mild aerobic and quite short daily exercise than later during postnatal life as shown by experiments reported previously.

Journal ArticleDOI
TL;DR: The force platform consists of a sandwhich of steel, Rockwool® and concrete plates about 900 × 700 mm in surface and showed a rectilinear response for static forces up to 500 kp with a stable zero value and in response to dynamic forces showed a resonance frequency of about 50 Hz, with a damping factor of 0.15.
Abstract: The force platform consists of a sandwhich of steel, Rockwool® and concrete plates about 900 × 700 mm in surface. Four steel rings were bolted to the under side of the steel plate in each corner. Each steel ring was furnished with only one strain gauge, two of which were placed on the outer- respectively on the inner side of each ring. The four strain gauges were connected to a measuring bridge. Before mounting the rings on the steel plate, the sensitivity to pressure of each ring was adjusted in such a way that they were all similar. Because of this the platform responded with a signal which was independent of where a pressure was applied within the surface of the platform. The platform showed a rectilinear response forstatic forces up to 500 kp with a stable zero value. In response todynamic forces the platform showed a resonance frequency of about 50 Hz, with a damping factor of 0.15. Calibration of dynamic forces was carried out by calculation of the forces during a vertical jump compared with what would be expected from the time of flight also registered by the platform-measuring-bridge-ink-writer-set-up. The time of flight was significantly higher (11%) than was expected from the time-force relations before take-off. This was explained partly by the relatively low damping factor in the system, partly by the subjects not extending their knees at landing on the platform.

Journal ArticleDOI
TL;DR: The finalistic implication of this mechanism is the prompt restoration of the potential maximal power of the muscle even in the absence of O2.
Abstract: The lactic acid (L.A.) concentration in blood after a 20 sec supramaximal exercise (2.5×\(\dot V_{O_2 \max } \)) has been measured in 4 subjects in the following experimental conditions:

Journal ArticleDOI
TL;DR: Isotonic exercise for both elbow flexors and knee extensors showed increasing clearance values up to 60% IS, and the relatively large scatter of the133Xe clearance method, and an inhomogenous perfusion of skeletal muscle may have masked any anticipated effect of the various O2 tensions.
Abstract: Isometric and isotonic endurance levels of both elbow flexors and knee extensors were tested during inspired gas mixtures of ca. 10%, 21% or 100% oxygen in nitrogen. The four work loads were set a 25, 50, 60 and 70% of maximal volitional isometric strength (IS). The isotonic exercise routine was carried out using weight lifting techniques of 20 repetitions per min from 75° to 105° of elbow flexion and knee extension respectively. Prior to, during, and after the endurance experiments133Xe clearance was monitored by light weight scintillation counters. A depot of 0.1 to 0.2 ml of isotonic saline containing 50 to 150 μCi of the isotope was used as an intramuscular tracer. The exercise clearance values varied inversely to the test load during isometric exercise. Isotonic exercise for both elbow flexors and knee extensors showed increasing clearance values up to 60% IS. Above this level a decrease in total clearance was recorded. Oxygen tension had no statistical effect on the clearance values. However, the relatively large scatter of the133Xe clearance method, and an inhomogenous perfusion of skeletal muscle may have masked any anticipated effect of the various O2 tensions. Variations due to the raised intramuscular pressure appeared to be much more dominant than the hypothezised variation due to the 3 set oxygen tensions.

Journal ArticleDOI
TL;DR: During digestion the histamine-induced depressor responses of trained subjects tended to approach that of untrained people, and this suggestion was confirmed by the isoproterenol studies, too.
Abstract: Blood pressure and heart rate responses elicited by norepinephrine, epinephrine and histamine were compared before and after duodenal acidification in 27 trained and untrained young healthy men. Before acidification trained subjects showed a lower sensitivity to norepinephrine and histamine and a slightly lower one to epinephrine. In order to explain these phenomena physical training was supposed to affect alpha, respectively beta adrenergic responsivity in a dissimilar manner. This suggestion was confirmed by the isoproterenol studies, too. Duodenal acidification decreased the catecholamine-induced pressor responses. Depressor responses to histamine did not change in the untrained subjects, whereas they increased in the trained group. Thus, during digestion the histamine-induced depressor responses of trained subjects tended to approach that of untrained people.

Journal ArticleDOI
TL;DR: It was suggested that three additive factors produced during strenuous exercise: decreased pH; increased hemoglobin concentration; and increased CO2 production result in by-product inhibition of 2,3 DPG synthesis.
Abstract: 15 untrained women were subjected to a walking treadmill test to determine the influence of maximal exercise upon synthesis of erythrocyte 2,3 DPG. Although there was a 9.8% increase in the 2,3 DPG content following exercise, there was a concomitant 9.4% increase in the hemoglobin level; therefore, when 2,3 DPG is expressed as a ratio to hemoglobin (See Article), there was no significant change as a result of exercise stress. It was suggested that three additive factors produced during strenuous exercise; decreased pH; increased hemoglobin concentration; and increased CO2 production result in by-product inhibition of 2,3 DPG synthesis. It is concluded that 2,3 DPG does not provide a physiologic benefit in the adaptation of the oxygen transport system to exercise.

Journal ArticleDOI
TL;DR: Because hypertrophy did not occur in the trained plantaris muscles, it appears that the trained animals had a higher muscle protein turnover rate, and it seems unlikely that testosterone plays an important role in these activity-related phenomena.
Abstract: We examined the changes induced by daily treadmill exercise on body weights, plantaris muscle weights, plantaris protein concentrations, andl-leucine-4,5-3H incorporation into plantaris muscles of normal and castrated young male guinea pigs and of castrated animals receiving testosterone replacement therapy, and compared the testosterone-1,2-3H uptake by plantaris muscles of trained normal guinea pigs to that of untrained animals. Trained animals exhibited significantly lower body and muscle weights and greater labeled leucine incorporation into sarcoplasmic and myofibrillar proteins but did not show significant changes in protein concentrations or labeled testosterone uptake. The level of physical activity of the young animals studied appeared to be more important than gonadal endocrine function in altering protein metabolism and muscle and body weights. Because hypertrophy did not occur in the trained plantaris muscles, which had elevated rates of labeled leucine incorporation, it appears that the trained animals had a higher muscle protein turnover rate. It seems unlikely that testosterone plays an important role in these activity-related phenomena.

Journal ArticleDOI
TL;DR: The results suggest that the vascularity of long bones is affected by physical training, and varying responses in different bones are perhaps due to the amount of mechanical stress during physical activity.
Abstract: The effect of physical training on the blood circulation of long bones was studied in growing rats and mice of NMRI-strain. The animals to be trained and their controls were about 2 weeks old at the beginning of the training. The training took place on a 5° inclined treadmill 5 days a week for 3 weeks in experiment I and 7 weeks in experiments II and III. The duration of the daily exercise was progressively increased over 3 weeks. The final exercise bouts were 80 min for moderate and 180 min for intensive training programs. The circulating red cell volume (ml/100 g bone) of the humeral, femoral and tibial bones of the trained animals was lower compared to the controls in all three experiments mainly due to reduced hematocrit values. The circulating blood volume (ml/100 g bone) decreased in the tibial bones of the trained animals in experiment I and showed a decreasing tendency in experiment III, but no significant differences between the groups were observed in the humeral and femoral bones. Yet, when related to the volume of the bones the circulating blood volume (ml/100 ccm bone) was significantly higher in the femoral bones of the trained animals, while the changes in the humeral bones were negligible (experiment III). The results suggest that the vascularity of long bones is affected by physical training. The varying responses in different bones are perhaps due to the amount of mechanical stress during physical activity.

Journal ArticleDOI
TL;DR: The results indicate that the finger tip capillary microhematocrit method is a valid indicator of venous blood hct.
Abstract: The purpose of this study was to determine if finger tip capillary blood hematocrit is a valid estimate of anticubital venous blood hematocrit at rest and after submaximal exercise. Simultaneous samples of finger tip capillary and venous blood were drawn from thirty-one subjects (15 males, 16 females) before and after a 15 min submaximal exercise on a bicycle ergometer. Venous and capillary blood hcts. were 42.0%±3.9 and 42.0%±3.5 respectively before exercise and 43.3%±3.5 and 42%±3.8 after exercise (¯X). The regression equation for predicting venous hct. from finger tip capillary blood after exercise was: Hctv = 0.87 Hctc+6.44 withr = 0.95 (P<0.05). The results indicate that the finger tip capillary microhematocrit method is a valid indicator of venous blood hct. following exercise.

Journal ArticleDOI
TL;DR: In 10 guinea pigs the gastrocnemius muscles on one side were tenotomised and the daily work load was lowered in the operated leg and increased in the control leg by the tenotomy, causing statistically significant differences between the two extremities.
Abstract: In 10 guinea pigs the gastrocnemius muscles on one side were tenotomised. By the tenotomy the daily work load of the gastrocnemius muscle was lowered in the operated leg (“untrained muscles”) and increased in the control leg (“trained muscles”). Before and several weeks after the operation blood flow was measured in the lower legs (by segmental plethysmography) and oxygen pressure was measured in the gastrocnemius muscles (by micro-Pt-electrodes) of the anesthetized animals.

Journal ArticleDOI
TL;DR: The results suggest a decreased cardiopulmonary working capacity at night, which is only of practical importance if the work will be done near the limit of endurance capacity.
Abstract: Bei sechs hochgeubten jugendlichen Radrennfahrern mit einem Durchschnittsalter von 16,3 Jahren und einer durchschnittlichen maximalen O2-Aufnahme von 4,9 l/min wurde die maximale O2-Aufnahme in Abstanden von 4 Std direkt bestimmt. Die Versuchsfolge wurde nach dem Lateinischen Quadrat festgelegt. Im submaximalen Bereich der O2-Aufnahme von 2,4 bis 4,4 l/min waren keine Unterschiede der Einzelfunktionen in Abhangigkeit von der Tageszeit zu finden. Dagegen wurden die folgenden Unterschiede zwischen den Maximal- und Minimalwerten gefunden: fur die maximale Leistung $$\dot W_{\max } $$ 12,4%, fur das maximale Atemzeitvolumen ( $$\dot V_{E\max } $$ ) 7,8%, fur die maximale O2-Aufnahme ( $$\dot V_{O_2 \max } $$ ) 5,7% und fur die maximale Herzfrequenz (H F max) 3,4%. Alle Funktionen hatten — mit Ausnahme der $$\dot V_{E\max } $$ — ihr Minimum um 3.00 Uhr; das Minimum der $$\dot V_{O_2 \max } $$ wurde dagegen bereits um 23.00 Uhr erreicht. Die Maxima der $$\dot V_{E\max } $$ und $$\dot V_{O_2 \max } $$ wurden um 15.00 Uhr, der $$\dot W_{\max } $$ undH F max um 7.00 Uhr und derH F Ruhe um 19.00 Uhr gemessen. Die Unterschiede zwischen den Maxima- und Minimawerten nach einseitiger Prufung waren in allen Einzelfunktionen signifikant (P<0,05). Die Ergebnisse sprechen fur eine geringere kardiopulmonale Leistungsfahigkeit in der Nacht. Diese Verminderung wird aber erst bedeutsam, wenn die Arbeit direkt an der Dauerleistungsgrenze geleistet werden muste. Auserdem ist daraus zu folgern, das indirekte Methoden zur Bestimmung der $$\dot V_{O_2 \max } $$ sowie die $$\dot W_{170} $$ in der Nachtzeit nicht sinnvoll zur Bestimmung der kardiopulmonalen Leistungsfahigkeit eingesetzt werden konnen, da die Voraussetzungen dieser Methoden auf die Tageszeit eingeschrankt sind.

Journal ArticleDOI
TL;DR: In this article, the maximal aerobic power of six highly trained young cyclists, mean age 16.3 years and mean VO2max 4.9 l/min, was directly measured at intervals of 4 hrs. A Latin square design was used for the test order.
Abstract: The maximal aerobic power of six highly trained young cyclist, mean age 16.3 years and mean VO2max 4.9 l/min, was directly measured at intervals of 4 hrs. A Latin square design was used for the test order. At submaximal work of O2-consumption 2.4 to 4.4 l/min no circadian variation of any single function was found. However, at maximal work load the differences between the maxima and minima values were 12.4% for maximal work output (W max), 7.8% for expiratory minute volume (V Emax), 5.7% for maximal aerobic power (VO2max) and 3.4% for maximal heart rate (H Rmax). All the functions--with the exception of VO2max-had their minima at 0300 hrs; the minima of VO2max was reached already at 2300 hours. The maxima-values of V Emax and VO2max were measured at 1500 hrs, of W max and H Rmax at 0700 and of H Rrest at 1900 hrs correspondingly. A one-tailed test showed significant differences between the maxima and minima values of all variables (P less than 0.05). The results suggest a decreased cardiopulmonary working capacity at night. However, this impairment is only of practical importance if the work will be done near the limit of endurance capacity. Besides it will suggest, that the indirect methods for assessing the cardiopulmonary capacity based on VO2max and W170 are not useful at nighttime, because the presuppositions for these methods are limited of the time of day.

Journal ArticleDOI
TL;DR: The 2,3-diphosphoglycerate concentration, oxygen half saturation pressure at pH 7.4, pH in plasma and red cells, and mean corpuscular hemoglobin concentration of venous blood were determined during unrestricted daily activity as well as during prolonged bed rest until noon.
Abstract: The 2,3-diphosphoglycerate (2,3-DPG) concentration, oxygen half saturation pressure at pH 7.4 (P50), pH in plasma and red cells, and mean corpuscular hemoglobin concentration (MCHC) of venous blood were determined during unrestricted daily activity (series I) throughout 24 hrs as well as during prolonged bed rest until noon (series II). In series I an almost synchronous diurnal behavior ofP50, 2,3-DPG, and plasma pH as well as red cell pH became significantly apparent with highest values in the afternoon. The [2,3-DPG] yielded most pronounced alterations, which made up to 13.5% of the average day value. During prolonged recumbency the [2,3-DPG] showed a nonsignificant tendency to decline; theP50 remained unchanged throughout that period. The possible reason for the missing [2,3-DPG] increase is a reduced change of red cell pH in series II. An influence of a posture dependent aldosterone secretion either directly on the 2,3-DPG metabolism or indirectly via mediating the red cell pH and thus ruling the formation of this organic phosphoris compound is discussed.

Journal ArticleDOI
TL;DR: In this paper, a simulation of the Unterarmtremor is presented, das der Tremor with einem Regelkreis beschrieben werden kann, der die Auswirkungen der Schwingungen eines mechanischen Schwingingssystems with einer stochastischen Kraftanregung and neuromuskulare Schwingingsen vereint.
Abstract: Im Leistungsdichtezentrum der Beschleunigung des Unterarm-, des Hand- und des Fingertremors treten grundsatzlich mehrere Frequenzmaxima auf. Mit sinusformigen Kraftanregungen, kleiner als 1% der Maximalkrafte, werden die Ubertragungsfunktionen bestimmt. Fur den Unterarmtremor wird gezeigt, das der Tremor mit einem Regelkreis beschrieben werden kann, der die Auswirkungen der Schwingungen eines mechanischen Schwingungssystems mit einer stochastischen Kraftanregung und neuromuskulare Schwingungen vereint. Die Bestimmung der Struktur der Einzelblocke wird durch Kreuzkorrelationen derEA(t) mit dem Tremor und einer Simulation am Analogrechner durchgefuhrt.