The effect of O2 breathing on maximal aerobic power

Summary Time of performance, blood lactic acid concentration (L.A.), heart rate (H.R.) and maximal oxygen consumption ( ) were measured during air and oxygen breathin in 11 subjects performing a supramaximal exercise with an O₂ requirement of 70 to 80 ml/kg·min to exhaustion. In addition the subjects were tested for maximal aerobic power with an indirect method. In one subject the rate of lactic acid increase in blood was also measured.The measured with both the direct and the indirect method appears to be about 8% higher when breathing pure oxygen; lactic acid production rate decreases correspondingly. Maximal H.R. and maximal L.A. concentration were found to be the same.In submaximal exercise steady state H.R. is lower by about 8–9 beats/min when breathing oxygen. Also when breathing oxygen H.R. is a linear function of the work load.From experimental data obtained in subjects of different , breathing both air or O₂, the energy equivalent of L.A. could be calculated as amounting to about 47 ml of O₂ or 235 cal per g of L.A. produced.This work was supported by a grant from the National Research Council of Italy (C.N.R.)     

Respiratory responses of elite oarsmen,former oarsmen,and highly trained non-rowers during rowing,cycling and running

The position of the body and use of the respiratory muscles in the act of rowing may limit ventilation and thereby reduce maximal aerobic power relative to that achieved in cycling or running, in spite of the greater muscle mass involved in rowing. This hypothesis was investigated for three groups of male subjects: nine elite senior oarsmen, eight former senior oarsmen and eight highly trained athletes unskilled in rowing. The subjects performed graded exercise to maximal effort on a rowing ergometer, cycle ergometer and treadmill while respiratory minute volume and oxygen consumption were monitored continuously. The VE at a given during intense submaximal exercise (greater than 75% of maximal ) was not significantly lower in rowing compared with that in cycling and treadmill running for any group, which would suggest that submaximal rowing does not restrict ventilation. At maximal effort, and for rowing were less than those for the other types of exercise in all the groups, although the differences were not statistically significant in the elite oarsmen. These data are consistent with a ventilatory limitation to maximal performance in rowing that may have been partly overcome by training in the elite oarsmen. Alternatively, a lower maximal VE in rowing might have been an effect rather than a cause of a lower maximal if maximal was limited by the lower rate of muscle activation in rowing.     

Exercise-induced changes in blood ammonia levels in humans

Summary Five male and two female subjects each performed a maximal aerobic capacity ( ) test, and two to four submaximal aerobic exercise bouts (requiring approximately 50 and 80% of the individual's measured ) on a motor-driven treadmill. Pre-exercise resting oxygen uptakes ( ) and heart rates were determined and a venous blood sample drawn prior to each work session. These same measurements were repeated at 4, 15, 30, and 45 min of the resting recovery period that followed each exercise experiment. Additionally, at the 30th min of each 45-min submaximal exercise, another peripheral venous blood sample was drawn following determination of and heart rate. In all blood samples, the hematocrit and concentrations of ammonia, lactate, pyruvate, glucose, hemoglobin, and total plasma proteins were measured.A significant exponential relationship was observed betwen blood ammonia levels and for all sample periods (pre-exercise rest, exercise, and post-exercise recovery). Peripheral venous blood ammonia levels were significantly correlated with levels of pyruvate and lactate, as these latter substrates exhibited a similar exponential relationship with as was observed with ammonia.This work was supported in part by the Air Force Office of Scientific Research, Air Force Systems Command, Grant AFOSR 73-2455 and by the National Institutes of Health, Grant NIH HD00235-6     

Changes in acid-base status of marathon runners during an incremental field test

Summary Four top-class runners who regularly performed marathon and long-distance races participated in this study. They performed a graded field test on an artificial running track within a few weeks of a competitive marathon. The test consisted of five separate bouts of running. Each period lasted 6 min with an intervening 2-min rest bout during which arterialized capillary blood samples were taken. Blood was analysed for pH, partial pressure of oxygen and carbon dioxide (P0₂ and PCO₂) and lactate concentration ([la^–]_b). The values of base excess (BE) and bicarbonate concentration ([HCO₃ ^–]) were calculated. The exercise intensity during the test was regulated by the runners themselves. The subjects were asked to perform the first bout of running at a constant heart rate f _c which was 50 beats · min^–1 below their own maximal f _c. Every subsequent bout, each of which lasted 6 min, was performed with an increment of 10 beats · min^–1 as the target f _c. Thus the last, the fifth run, was planned to be performed with fc amounting to 10 beats · min^–1 less than their maximal f _c. The results from these runners showed that the blood pH changed very little in the bouts performed at a running speed below 100% of mean marathon velocity ( _m). However, once _mwas exceeded, there were marked changes in acid-base status. In the bouts performed at a velocity above the _mthere was a marked increase in [la^–]_b and a significant decrease in pH, [HCO₃ ^–], BE and PCO₂. The average marathon velocity ( _m) was 18.46 (SD 0.32) km·h^–1. The [la^–]_b at a mean running velocity of 97.1 (SD 0.8) % of _mwas 2.33 (SD 1.33) mmol ·l^–1 which, compared with a value at rest of 1.50 (SD 0.60) mmol·l^–1, was not significantly higher. However, when running velocity exceeded the vm by only 3.6 (SD 1.9) %, the [la^–]b increased to 6.94 (SD 2.48) mmol·l-1 (P<0.05 vs rest). We concluded from our study that the highest running velocity at which the blood pH still remained constant in relation to the value at rest and the speed of the run at which [la^–]_b began to increase significantly above the value at rest is a sensitive indicator of capacity for marathon running.     

Improved estimation of total oxygen uptake in exercise by evaluation of aerobic fitness

Summary The purpose of the present study was to contrive a new practical method for estimating total O₂ uptake during exercise from total heart beats after individual evaluation of aerobic fitness levels. Twenty healthy male subjects participated in cycle ergometer tests, maximal O₂ uptake ( ) tests and various simple tests including simple endurance tests. From the cycle ergometer results, the following formula for estimating total O₂ uptake in exercise was determined: (ml·kg^–1)=SR₁₂₅×(45.8× mean HR+4268)×THB×10^–4 where , THB, and mean HR are total O₂ uptake, total heart beats, and mean heart rate (beats · min_–1) in exercise, respectively, and SR₁₂₅ is the slope of the regression line between accumulated heart beats and accumulated O₂ uptake during exercise at 125 beats · min^–1 of mean HR. SR₁₂₅ had a significant correlation not only with but also with each score (X) in any simple endurance tests such as, for example, a step test for 2 min. In this case, accordingly, SR₁₂₅ can be found as; SR₁₂₅=–0.00118X+0.3478. These formulae indicate that the total O₂ uptake of any exercising subject can be estimated from his total heart beats regardless of intensities of exercise when his aerobic fitness level is evaluated by the simple endurance test. The total O₂ uptake estimated by our method was compared to that measured by the Douglas bag method, and the discrepancy between the two results was less than the errors of values estimated by traditional methods.Supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (grant no. 57780095)     

The influence of weekly training distance on fractional utilization of maximum aerobic capacity in marathon and ultramarathon runners

Summary This study was designed to examine the interrelationships between performance in endurance running events from 10 to 90 km, training volume 3–5 weeks prior to competition, and the fractional utilization of maximal aerobic capacity (% ) during each of the events. Thirty male subjects underwent horizontal treadmill testing to determine their , and steady-state at specific speeds to allow for calculation of % sustained during competition. Runners were divided into groups of ten according to their weekly training distance (group A trained less than 60 km · week^–1, group B 60 to 100 km · week^–1, and group C more than 100 km · week^–1). Runners training more than 100 km · week^–1 had significantly faster running times (average 19.2%) in all events than did those training less than 100 km · week^–1. or % sustained during competition was not different between groups. The faster running speed of the more trained runners, running at the same % during competition, was due to their superior running economy (19.9%). Thus all of the group differences in running performance could be explained on the basis of their differences in running economy. These findings suggest either that the main effect of training more than 100 km · week^–1 may be to increase running economy, or that runners who train more than 100 km · week^–1 may have inherited superior running economy. The finding that the maximal horizontal running speed reached during the progressive maximal treadmill test was a better predictor (r=0.72) of running performance at all distances than was the (r=0.54) suggests that peak treadmill running speed can predict performance in endurance running events.     

Maximal oxygen uptake in 153 elderly Dutch people (69–87 years) who participated in the 1993 Nijmegen 4-day march

There are no studies on oxygen uptake of groups of physically active subjects aged over 70. This study describes the maximal oxygen uptake ( ) of 153 elderly people who completed the Nijmegen annual 4-day march (at least 30 km · day^–1) in 1993. A total of 97 men with a mean age of 76.7 (SD 4.6) and 56 women with a mean age of 72.8 (SD 3.6) years participated in the study. The was determined using incremental cycle ergometry; 91 men and 49 women completed a maximal exercise test. Criteria for maximal performance were respiratory exchange ratio equal to or greater than 1.00, vertilatory equivalent for oxygen equal to or greater than 30.00 and maximal heart rate equal to or greater than (beats · min^–1) 210 minus age (years). Mean maximal power output was 148.2 (SD 27.2) W and 120.4 (SD 20.5) W, mean · body mass^–1 was 26.8 (SD 4.9) ml · kg^–1 · min^–1 and 24.6 (SD 4.7) ml · kg^–1 · min^–1, mean maximal heart rate was 152 (SD 18), and 157 (SD 14) beats · min^–1 in men and women respectively. The mean · body mass^–1 was about 20% higher than reported in other studies on subjects over 70 years of age. Mean maximal heart rate was about 10 beats · min^–1 higher than predicted from the equation 220 — age. The negative effect of chronic disease on · body mass^–1 was smaller than in a sedentary reference population. The mean decline in · body mass^–1 with age was 0.46 and 0.38 ml·kg^–1·min^–1 per year in the men and women respectively, which is the same rate as found in younger subjects. It was concluded that regular exercise might substantially increase aerobic power in the physically active elderly, even when they have chronic disease, and that it is unlikely that there is an accelerated loss of aerobic power in physically active elderly people aged over 70 year.     

Blood lactate vs. exhaustive exercise to evaluate aerobic fitness

Summary This study compared the predictive power of a lactate-related index determined during submaximal cycle exercise to that of an exhaustive cycle ergometer test for evaluating the endurance exercise capacity of soldiers. The subjects (n=48 males) performed a continuous exercise test to voluntary exhaustion on the cycle ergometer. Power output (PO) increased by 50 W steps each fourth min, with determinations of heart rate (HR), RPE and blood lactate concentrations (HLa) just prior to each PO increase. The PO at a 4 mmol L⁻¹ HLa concentration (w_OBLA) was interpolated; based on the time to exhaustion the maximal PO that could be maintained for 6 min was calculated from previously documented formulae. Subjects were timed during a 3000 m cross-country run. Both the cycle test and the run were performed again 3 months later, as was an additional 3000 m run with full military equipment weighing about 21 kg. All 3000 m times were significantly correlated (p<0.05) with both and W_OBLA; similar predictive power was demonstrated for both and W_OBLA, suggesting that accuracy in evaluation would not be sacrificed by substituting the submaximal for the exhaustive exercise test. HR and RPE-related indices showed markedly lower predictive power. The results extend the previously documented relationship between HLa during treadmill ergometry and running performance to include the use of cycle ergometry for the evaluation of running performance. The results also proved applicable to running performance while load carrying. Quote DCIEM Report No. 85-P-15     

Assessment of physical activity in oxidative and anaerobic maximal exercise

Muscular power depends on the rate of the exergonic reactions taking place in the muscles during activity. These are essentially a) splitting of the high energy phosphate compounds (phosphagen), b) glycolysis and lactic acid formation, and c) oxidative reactions; b) and c) are used to rebuild the phosphagen broken down as from a).The rate of reaction a) is sensibly constant during the first 6–8 secs of work at maximum rate, then declining with the exhaustion of phosphagen. By measuring the maximal rate of work in an exercise such as running up a staircase for 1–2 secs only (4–8 steps), the maximal anaerobic power can be measured: this is done by measuring the time of performance with a timer sensitive to 0.01 secs, and by knowing the height of the step. The test is fast and easy and well accepted by the subject as the time of performance is too short to lead to exhaustion. Thisanaerobic power is ab 3 times theaerobic power.Theaerobic power is measured by stepping up and down at two fixed submaximal rates and by measuring the heart rates (f₁ and f₂): from this, by means of a formula or a nomogram, the maximal O₂ consumption, or the aerobic power, is calculated.Both the aerobic and the anaerobic power tests involve familiar exercises that do not require training, or calibration of apparatuses, or excessive stress on the subjects.A convenient representation of the main circulatory and respiratory changes ( , heart frequency and stroke volume. , Hb, and others) taking place in muscular exercise at sea level and at altitude is also given.This paper was read on Sept. 17th, 1965 in Kyoto, Japan at the International Symposium on Environmental Physiology, promoted by the International Biological Programme, and supported by IUPS, FASEB and HA Section of J.I.B.P.     

Cardiorespiratory effects of respiratory protective devices during exercise in well-trained men

Summary The effects of a filtering device, an air-line breathing apparatus and a self-contained breathing apparatus (SCBA) on pulmonary ventilation, oxygen consumption and heart rate were studied in 12 well-trained firemen aged 21–35 years. Their average maximal oxygen consumption ( max) was 64.9 ml·min^–1·kg^–1. Sequential tests without and with the respirator were performed on a treadmill. The continuous test contained five components, each of which lasted 5 min: sitting at rest, walking at 20%, 40%, and 60% of the individual max, and recovery sitting. During the higher submaximal work levels and recovery, ventilation, heart rate, and oxygen consumption in particular increased more with respirators than without them. At the highest work level the increments in oxygen consumption caused by the respirators were 13%, (8.7 ml·min^–1·kg^–1), 7% (4.4 ml·min^–1·kg^–1), and 20% (12.7 ml·min^–1·kg^–1) of max. All three respirators hampered respiration, resulting in hypoventilation. The additional effort of breathing and the weight of the apparatus (15 kg with the SCBA) increased the subjects' cardiorespiratory strain so clearly that the need for rest periods and the individual's work capacity when the respirators are worn must be carefully considered, particularly with the SCBA.     

Etude pratique des postes de travail et critique des résultats

Summary Oxygen consumption and heart rate have been measured by 47 workers of a motor car factory. 20 were also investigated in the laboratory in order to determine on the bicycle ergometer the same parameters at different loads and the individual aerobic power. The advantages of telemetry for the measurement of heart rate are presented. The relationf _h/ is quite the same at work and on the ergometer. Consequently, it is possible to use the heart rate only to measure the energy expenditure at work by these industrial workers. Is is possible to determine on the ergometer the load equivalent to the industrial work. In this case, the equivalent load is about 75 watts ( between 800 and 1260 ml/min.). In peak activity, our workers need no more than 55% of their aerobic power and no more than 78% of their maximal heart rate. During a working period of 3 hours, obviously with resting periods, the workers use about 58% of their maximal heart rate and about 24% of their aerobic power. The importance of the percentage of aerobic power and of maximal heart rate used at rest should be taken into account for the interpretation of the results. In our study each worker able to perform 75 watts with a heart rate lesser than 78% of his maximal heart rate and with an oxygen uptake lesser than 55% of his aerobic power should be considered fit for this industrial work. The utilization of the basal heart rate as proposed byHettinger seems us inaccurate and obviously inadequate for rehabilitation of cardiac and pulmonary patients. The study of energy expenditure during occupational work requires further investigations in order to know what percentage of the aerobic power can be allowed during a 8 hours continuous activity in other jobs. The importance of peak works frequency needs further studies.

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Ce travail a été réalisé avec l'aide financière de la Communauté Européenne du Charbon et de l'Acier.     

Cardiorespiratory response to treadmill and bicycle exercise in runners

Summary Maximal aerobic power and related variables during submaximal work were determined on the bicycle ergometer and on the treadmill in nine long-distance runners and in nine control subjects.During submaximal work, heart rate and pulmonary ventilation were similar with the two exercise procedures in each group, but the runners had lower values than the control subjects.During maximal exercise, oxygen uptake and pulmonary ventilation reached higher levels on the treadmill than on the bicycle ergometer. The difference in max was not significant in the control subjects (4.4%), but was more pronounced (12.8%) and highly significant (p<0.01) in the runners. The intergroup differences for max between runners and controls were more marked during treadmill running (17.3%) than during bicycle exercise (8.5%).It is concluded that the differences between the max values obtained on the bicycle ergometer and on the treadmill are influenced by the training conditions of the subjects and that bicycle ergometry leads to a marked underestimation of maximal oxygen uptake in runners.     

Evaluation of physical fitness from field tests at high altitude in circumpubertal boys: comparison with laboratory data

Field tests of running and laboratory tests were performed in La Paz [high altitude (HA), 3700 m] and in Clermont-Ferrand [low altitude (LA), 300 m] to investigate their validity at HA. Prepubertal boys of mean ages 10.6 years (HA1,n = 16; LA1,n = 28) and pubertal boys of 13.7 years (HA2,n = 12; LA2,n = 41) took part in the study. All the boys performed a 30-m sprint (v _30m), a 30-s shuttle run (v _3os) and a progressive shuttle run test until their maximal aerobic velocity (v _maxsRT). Maximal oxygen consumption was extrapolated from the last test. . In the laboratory, the boys performed a force-velocity test (P _max), a Wingate test (P _Wing) and a graded test to measure maximal oxygen consumption ; direct method) on a cycle ergometer. At similar ages, there was no significant difference between HA and LA boys forv _30m andP _max. Thev _30s of HA boys was 3%–4% lower than those of LA boys (P<0.05); there was no significant difference forP _Wing. Significant relationships were observed at both altitudes betweenP _max (watts per kilogram) andv _30m (HA:r=0.76; LA:r=0.84) and betweenP _Wing andv _30s (HA:r=0.67; LA:r = 0.77); the slopes and the origins were the same at HA and LA. The ,v _maxSRT and were lower by 9%, 12% and 20%, respectively, at HA than at LA (P<0.05). However, the relationships between and (litres per minute) at HA (r=0.88) and at LA (r=0.93) were identical. In conclusion, chronic hypoxia did not modify performance in very short dash exercises. The influence of HA appeared when the exercise duration increased and, during a maximal shuttle run test, performance was reduced by 10% at HA. Moreover, it was possible to assessP _max,P _Wing and at HA as well as at LA from field tests.     

Sex-related differences in free plasma catecholamines in individuals of similar performance ability during graded ergometric exercise

Summary Sex-related differences of catecholamine responses were evaluated in nine healthy women and six age-matched men at rest and during incremental treadmill erxercise. Heart rate, oxygen uptake ( ), glucose and lactate blood levels as well as the free plasma catecholamines, noradrenaline and adrenaline, were determined. No significant differences were observed for these parameters between the two groups at rest. The females had relative and maximal running velocities similar to the males, which points to a comparable dynamic performance ability. However, at identical work loads, noradrenaline, adrenaline and glucose levels were significantly higher in women than in men. Lactate, heart rate and relative showed a similar tendency at submaximal exercise levels, indicating higher strain at identical stress levels in women. The reason for the higher sympathetic activity in women at identical work loads may be their relatively smaller skeletal muscle mass in relation to the loads during this test.Supported by Bundesinstitut für Sportwissenschaften, Cologne-Lövenich, FRG     

Respiratory sinus arrhythmia alteration following training in endurance athletes

Summary Significant increases in maximum oxygen consumption ( ) were noted in nine young track athletes following an 8-week high-intensity running period (P < 0.05). was measured, prior to and following the training program, using an on-line, open-circuit spirometry system. Parasympathetic activity was assessed using heart period variation (R-R interval in milliseconds) during carefully controlled breathing activity (R sinus arrhythmia). Following the training program, a 7.3% increase in aerobic capacity was associated with a 23.1% augmentation of efferent parasympathetic activity (P < 0.01). These data suggest that enhanced aerobic capacity increases efferent parasympathetic tone.     

Dissociation between\dot V_{O_2 \max } and ventilatory threshold responses to endurance training

Summary The purpose of this investigation was to determine whether the ventilatory gas exchange threshold (T_vent) changes significantly during the first 1–3 weeks of endurance training. Six men were studied during 3 weeks of training, which consisted of pedaling on a cycle ergometer 6 d·wk 30 min per session at 70% of pretraining . At the end of each week, T_vent, and maximal and submaximal heart rates were determined during an incremental exercise test on the cycle ergometer. Constant-load submaximal exercise blood lactate concentrations were determined during training sessions on Monday, Wednesday, and Friday of each week of training. T_vent did not change significantly during the 3 weeks of training (+ 0.09 l·min^–1;P>0.05). In contrast, significant changes occurred in all other training indexes measured. increased by 0.36 l·min^–1 (P<0.05) after just 2 weeks of training and did not change further after 3 weeks. Significant reductions (40–45%;p<0.05) in blood lactate levels during training sessions occurred by the middle of the 2nd week of training. Decreases in maximal (~ 11 bt·min^–1) and submaximal (~ 14 bt·min^–1) exercise heart rates after 1 week of training were significant (P<0.05). The results demonstrate that changes in T_vent lag behind alterations in several other cardiovascular and metabolic parameters in response to endurance training. The dissociation between the significant improvement in and the lack of a significant increase in T_vent during the first 3 weeks of training indicates that the exercise-induced changes in these two parameters are regulated by different mechanisms.     

The effects of continuous and interval training in women and men

Summary Fourteen Subjects (6 male, 8 female) participated in a training program upon a bicycle ergometer for 7 weeks. Group CT followed a continuous training regimen 4 days per week at 70% O₂ max. Group IT trained by an interval method at 100% O₂ max. The duration of each training session was assigned so that each subject would complete 10,000 kpm of work per session during the first week. Each subsequent week, the work load was increased 3000 kpm. Pretraining tests included O₂ max, standard 7 min tests at 80% O₂ and 90% O₂, an endurance test at 90%, and an intense anaerobic work bout at 2400 kpm. Variables assessed were O₂, HR, and blood lactic acid concentrations. The mean increase in O₂ max was 5.1 ml/kg min (15%) for both groups with a corresponding increase in maximal lactate of 20 mg-%. The response to the post-training tests was nearly identical for both groups: submaximal heart rate at the same absolute work load declined 17 beats/min (CT) and 15 beats/min (IT), submaximal lactate levels declined significantly, endurance ride duration increased 26 min. Continuous and interval training at 70% and 100% O₂ max respectively produce identical changes in heart rate response, blood lactic acid concentration and O₂ max when the total work load is equated per training session.     

The respiratory system as an exercise limiting factor in normal trained subjects

Summary Recently, we have shown that an untrained respiratory system does limit the endurance of submaximal exercise (64% peak oxygen consumption) in normal sedentary subjects. These subjects were able to increase breathing endurance by almost 300% and cycle endurance by 50% after isolated respiratory training. The aim of the present study was to find out if normal, endurance trained subjects would also benefit from respiratory training. Breathing and cycle endurance as well as maximal oxygen consumption ( ) and anaerobic threshold were measured in eight subjects. Subsequently, the subjects trained their respiratory muscles for 4 weeks by breathing 85-1601 · min^–1 for 30 min daily. Otherwise they continued their habitual endurance training. After respiratory training, the performance tests made at the beginning of the study were repeated. Respiratory training increased breathing endurance from 6.1 (SD 1.8) min to about 40 min. Cycle endurance at the anaerobic threshold [77 (SD 6) % ] was improved from 22.8 (SD 8.3) min to 31.5 (SD 12.6) min while and the anaerobic threshold remained essentially the same. Therefore, the endurance of respiratory muscles can be improved remarkably even in trained subjects. Respiratory muscle fatigue induced hyperventilation which limited cycle performance at the anaerobic threshold. After respiratory training, minute ventilation for a given exercise intensity was reduced and cycle performance at the anaerobic threshold was prolonged. These results would indicate the respiratory system to be an exercise limiting factor in normal, endurance trained subjects.     

The relationship between test protocol and the development of exercise-induced hypoxemia (EIH) in highly trained athletes

Healthy male endurance-trained cyclists [n = 11, age = 27.3 (3.9) years; mass = 73.0 (9.3) kg; height = 180.5 (6.9) cm; maximal oxygen consumption ( = 71.1 (5.8) ml · kg^–1 · min^–1, mean ± (SD)] were recruited to assess the relationship between test protocol and the development of desaturation of arterial hemoglobin with oxygen, during incremental exercise tests to maximal aerobic capacity . All subjects demonstrated resting pulmonary function within normal limits [forced vital capacity (FVC) = 6.0 (0.9); forced expiratory volume (FEV_1.0) = 4.9 (0.6); FEV_1.0/FVC = 0.8 (0.1)] and completed three ramped tests (Mijnhardt KEM-3 electronically braked cycle ergometer) beginning at 0 W with increments of either 20, 30 or 40 W · min^–1. All periods of testing were separated by a minimum of 72 h. , peak minute ventilation (Medical Graphics, CPX-D), peak heart rate (ƒ_cpeak)), peak power output , and minimum percentage arterial oxyhemoglobin saturation (%S _aO_2min) (Omeda Biox 3740 pulse oximeter) were determined. There were no significant differences (p > 0.05) in [191.5 (26.2), 196.0 (24.4), 194.3 (23.9) 1 · min^–1] ƒ_cpeak [191.4 (7.0), 190.3 (5.5), 187.8 (5.9) beats · min^–1], [5.0 (0.5), 5.1 (0.4), 5.1 (0.5) 1 · min^–1] or %S _aO_2min [89.5 (1.5), 89.6 (1.3), 90.0 (2.3)] between protocols. The 20-W protocol [417 (27) W] demonstrated significantly lower (P < 0.05) than the 30-W [434 (36) W] and 40-W [453 (38) W] protocols, indicating that peripheral fatigue may play an important factor in response to these tests. The results of this study demonstrate that arterial desaturation occurs as a result of intense exercise in highly trained athletes independent of the rate of attainment of .     

A new method for the evaluation of anaerobic running power in athletes

Summary A new maximal anaerobic running power (MARP) test was developed. It consisted ofn · 20-s runs on a treadmill with a 100-s recovery between the runs. During the first run the treadmill speed was 3.97 m · s^–1 and the gradient 5°. The speed of the treadmill was increased by 0.35 m · s^–1 for each consecutive run until exhaustion. The height of counter-movement jumps and blood lactate concentration ([1a^–]_b) were measured after each run. Submaximal ([la^– ] b = 3 mmol · l^–1 and 10 mmol · l^–1) and maximal speed and power ( , and , respectively) were calculated andW was expressed in oxygen equivalents according to the American College of Sports Medicine equation. Thirteen male athletes whose times over 400 m ranged from 47.98 s to 54.70 s served as subjects. In the MARP-test the speed at exhaustion was 6.89 (SD 0.28) m · s^–1 corresponding to a of 118 (SD 5) ml · kg^–1 · min^–1. The peak [1a^–]_b after exhaustion was 17.0 (SD 1.6) mmol · l^–1 . A significant correlation (r=0.89,P<0.001) was observed between the and the average speed in the 400-m sprint. The maximal 20-m sprinting speed on a track and correlated with both the and the 400-m speed. It was concluded that the new method allows the evaluation of several determinants of maximal anaerobic performance including changes in the force-generating capacity of leg muscles and [la^–]_b relative to the speed of the sprint running. The [1a^–]_b at submaximal sprinting speed was suggested as describing the anaerobic sprinting economy.