Energy expenditure during simulated rowing

Metabolic function was measured by open-circuit spirometry for 310 competitive oarsmen during and following a 6-min maximal rowing ergometer exercise. Aerobic and anaerobic energy contributions to exercise were estimated by calculating exercise O2 cost and O2 debt.O2 debt was measured for 30 min of recovery using oxygen consumption (Vo2) during light rowing as the base line. Venous blood lactates were analyzed at rest and at 5 and 30 min of recovery. Maximal ventilation volumes ranged from 175 to 22l 1/min while Vo2 max values averaged 5,950 ml/min and 67.6 ml/kg min. Maximal venous blood lactates ranged from 126 to 240 mg/100 ml. Average O2 debt equaled 13.4 liters. The total energy cost for simulated rowing was calculated at 221.5 kcal assuming 5 kcal/l O2 with aerobic metabolism contributing 70% to the total energy released and anaerobiosis providing the remaining 30%. Vo2 values for each minute of exercise reflect a severe steady state since oarsmen work at 96-98% of maximal aerobic capacity. O2 debt and lactate measurements attest to the severity of exercise and dominance of anaerobic metabolism during early stages of work.     

Predicting maximal aerobic capacity (VO2max) from the critical velocity test in female collegiate rowers

The objective of this study was to examine the relationship between the critical velocity (CV) test and maximal oxygen consumption (VO2max) and develop a regression equation to predict VO2max based on the CV test in female collegiate rowers. Thirty-five female (mean ± SD; age, 19.38 ± 1.3 years; height, 170.27 ± 6.07 cm; body mass, 69.58 ± 0.3 1 kg) collegiate rowers performed 2 incremental VO2max tests to volitional exhaustion on a Concept II Model D rowing ergometer to determine VO2max. After a 72-hour rest period, each rower completed 4 time trials at varying distances for the determination of CV and anaerobic rowing capacity (ARC). A positive correlation was observed between CV and absolute VO2max (r = 0.775, p < 0.001) and ARC and absolute VO2max (r = 0.414, p = 0.040). Based on the significant correlation analysis, a linear regression equation was developed to predict the absolute VO2max from CV and ARC (absolute VO2max = 1.579[CV] + 0.008[ARC] - 3.838; standard error of the estimate [SEE] = 0.192 L·min(-1)). Cross validation analyses were performed using an independent sample of 10 rowers. There was no significant difference between the mean predicted VO2max (3.02 L·min(-1)) and the observed VO2max (3.10 L·min(-1)). The constant error, SEE and validity coefficient (r) were 0.076 L·min(-1), 0.144 L·min(-1), and 0.72, respectively. The total error value was 0.155 L·min(-1). The positive relationship between CV, ARC, and VO2max suggests that the CV test may be a practical alternative to measuring the maximal oxygen uptake in the absence of a metabolic cart. Additional studies are needed to validate the regression equation using a larger sample size and different populations (junior- and senior-level female rowers) and to determine the accuracy of the equation in tracking changes after a training intervention.     

What distinguishes the Olympic level heavyweight rowers from other internationally successful rowers?

The aim of the study was to determine which of the observed variables differentiate mostly the successful (Olympic Games contenders) from the less successful rowers (Internationally competitive rowers) and in order for that anthropometric and physiological profile of elite Croatian heavyweight rowers was assessed. Twenty nine national rowing champions were divided into two groups according to their international competitive achievements. Physiological characteristics were assessed during a continuous progressive rowing ergometer test. Differences were determined using the independent t-test with Bonferroni corrections. Successful rowers had somewhat larger values of almost all of the observed lengths, widths and girths (exceptions: chest and thigh girth). In addition, their maximal oxygen uptake was significantly higher (5.51 +/- 0.40 L/min vs. 5.16 +/- 0.39 L/min; p < 0.05) as was their power output at anaerobic threshold (346.3 +/-17.9 W vs. 319.2 +/- 20.1 W; p < 0.01). Less successful Croatian rowers should target their training in the upcoming years towards increasing, primarily, maximal oxygen uptake and power output at anaerobic threshold.     

Development of a rowing-specific VO2max field test

The purpose of this study was to develop an aerobic capacity test for rowers using minimal equipment that could be used in the field. Thirty rowers (15 men and 15 women) between the ages of 18 and 26 years were recruited on a volunteer basis from the District of Columbia metro area. The testing protocol consisted of a maximum of 7 2-minute stages on a rowing ergometer, separated by 30-second breaks where lactic acid concentrations were analyzed. Starting intensity for men was 200 W, although women started at 150 W, and each stage increased by 50 W. Expired gasses were collected during the test, and athletes were asked to row until maximal volition so that the directly measured VO2max could be compared to predicted values. Peak heart rates from each completed stage were plotted, and regression equations were calculated to predict VO2max. Separate regression equations were calculated for men and women. The predicted VO2max values were approximately 23 and 25% lower than what was actually achieved for men and women, respectively. Heart rate was a stronger correlate of VO2max in men compared with in women. Among men, we observed a moderate and statistically significant correlation (r = 0.55; p = 0.05), whereas among women, no such agreement was observed (r = -0.05; p > 0.85). The principle finding of this study was that the test was adequate in predicting VO2max in men but was inadequate in its prediction in women. With slight modifications to the testing protocol, stronger correlations and a more accurate prediction of VO2max is expected in men.     

Effect of fitness on arm vascular and metabolic responses to upper body exercise

We investigated arm perfusion and metabolism during upper body exercise. Eight average, fit subjects and seven rowers, mean +/- SE maximal oxygen uptake (VO2 max) 157 +/- 7 and 223 +/- 14 ml O2. kg(-0.73).min(-1), respectively, performed incremental arm cranking to exhaustion. Arm blood flow (ABF) was measured with thermodilution and arm muscle mass was estimated by dual-energy X-ray absorptiometry. During maximal arm cranking, pulmonary VO2 was approximately 45% higher in the rowers compared with the untrained subjects and peak ABF was 6.44 +/- 0.40 and 4.55 +/- 0.26 l/min, respectively (P < 0.05). The arm muscle mass for the rowers and the untrained subjects was 3.5 +/- 0.4 and 3.3 +/- 0.1 kg, i.e., arm perfusion was 1.9 +/- 0.2 and 1.4 +/- 0.1 l blood.kg(-1).min(-1), respectively (P < 0.05). The arteriovenous O2 difference was 156 +/- 7 and 120 +/- 8 ml/l, respectively, and arm VO2 was 0.98 +/- 0.08 and 0.60 +/- 0.04 l/min corresponding with 281 +/- 22 and 181 +/- 12 ml/kg, while arm O(2) diffusional conductance was 49.9 +/- 4.3 and 18.6 +/- 3.2 ml.min(-1).mmHg(-1), respectively (P < 0.05). Also, lactate release in the rowers was almost three times higher than in the untrained subjects (26.4 +/- 1.1 vs. 9.5 +/- 0.4 mmol/min, P < 0.05). The energy requirement of an approximately 50% larger arm work capacity after long-term arm endurance training is covered by an approximately 60% increase in aerobic metabolism and an almost tripling of the anaerobic capacity.     

Effect of pedal cadence on the accumulated oxygen deficit, maximal aerobic power and blood lactate transition thresholds of high-performance junior endurance cyclists

In this study we investigated the effect of pedal cadence on the cycling economy, accumulated oxygen deficit (AOD), maximal oxygen consumption (VO2max) and blood lactate transition thresholds of ten high-performance junior endurance cyclists [mean (SD): 17.4 (0.4) years; 183.8 (3.5) cm, 71.56 (3.75) kg]. Cycling economy was measured on three ergometers with the specific cadence requirements of: 90-100 rpm for the road dual chain ring (RDCR90-100 rpm) ergometer, 120-130 rpm for the track dual chain ring (TDCR120-130 rpm) ergometer, and 90-130 rpm for the track single chain ring (TSCR90-130 rpm) ergometer. AODs were then estimated using the regression of oxygen consumption (VO2) on power output for each of these ergometers, in conjunction with the data from a 2-min supramaximal paced effort on the TSCR90-130 rpm ergometer. A regression of VO2 on power output for each ergometer resulted in significant differences (P<0.001) between the slopes and intercepts that produced a lower AOD for the RDCR90-100 rpm [2.79 (0.43) l] compared with those for the TDCR120-130 rpm [4.11 (0.78) l] and TSCR90-130 rpm [4.06 (0.84) l]. While there were no statistically significant VO2max differences (P = 0.153) between the three treatments [RDCR90-100 rpm: 5.31 (0.24) l x min(-1); TDCR120-130 rpm; 5.33 (0.25) 1 x min(-1); TSCR90-130 rpm: 5.44 (0.27) l x min(-1)], all pairwise comparisons of the power output at which VO2max occurred were significantly different (P<0.001). Statistically significant differences were identified between the RDCR90-100 rpm and TDCR120-130 rpm tests for power output (P = 0.003) and blood lactate (P = 0.003) at the lactate threshold (Thla-), and for power output (P = 0.005) at the individual anaerobic threshold (Thiat). Our findings emphasise that pedal cadence specificity is essential when assessing the cycling economy, AOD and blood lactate transition thresholds of high-performance junior endurance cyclists.     

Maximal aerobic capacity for repetitive lifting: comparison with three standard exercise testing modes

A multi-stage, repetitive lifting maximal oxygen uptake (VO2max) test was developed to be used as an occupational research tool which would parallel standard ergometric VO2max testing procedures. The repetitive lifting VO2max test was administered to 18 men using an automatic repetitive lifting device. An intraclass reliability coefficient of 0.91 was obtained with data from repeated tests on seven subjects. Repetitive lifting VO2max test responses were compared to those for treadmill, cycle ergometer and arm crank ergometer. The mean +/- SD repetitive lifting VO2max of 3.20 +/- 0.42 l.min-1 was significantly (p less than 0.01) less than treadmill VO2max (delta = 0.92 l.min-1) and cycle ergometer VO2max (delta = 0.43 l.min-1) and significantly greater than arm crank ergometer VO2max (delta = 0.63 l.min-1). The correlation between repetitive lifting oxygen uptake and power output was r = 0.65. VO2max correlated highly among exercise modes, but maximum power output did not. The efficiency of repetitive lifting exercise was significantly greater than that for arm cranking and less than that for leg cycling. The repetitive lifting VO2max test has an important advantage over treadmill or cycle ergometer tests in the determination of relative repetitive lifting intensities. The individual curves of VO2 vs. power output established during the multi-stage lifting VO2max test can be used to accurately select work loads required to elicit given percentages of maximal oxygen uptake.     

A new approach to assessing maximal aerobic power in children: the Odense School Child Study

In two experiments maximal aerobic power (VO2max) calculated from maximal mechanical power (Wmax) was evaluated in 39 children aged 9-11 years. A maximal multi-stage cycle ergometer exercise test was used with an increase in work load every 3 min. In the first experiment oxygen consumption was measured in 18 children during each of the prescribed work loads and a correction factor was calculated to estimate VO2max using the equation VO2max = 12.Wmax + 5.weight. An appropriate increase in work rate based on height was determined for boys (0.16 W.cm-1) and girls (0.15 W.cm-1) respectively. In the second experiment 21 children performed a maximal cycle ergometer exercise test twice. In addition to the procedure in the first experiment a similar exercise test was performed, but without measurement of oxygen uptake. Calculated VO2max correlated significantly (p less than 0.01) with those values measured in both boys (r = 0.90) and girls (r = 0.95) respectively, and the standard error of estimation for VO2max (calculated) on VO2max (measured) was less than 3.2%. Two expressions of relative work load (%VO2max and %Wmax) were established and found to be closely correlated. The relative work load in %VO2max could be predicted from the relative work load in %Wmax with an average standard error of 3.8%. The data demonstrate that calculated VO2max based on a maximal multi-stage exercise test provides an accurate and valid estimate of VO2max.     

Relative vs. absolute physiological measures as predictors of mountain bike cross-country race performance

The aims of this study were to document the effect terrain has on the physiological responses and work demands (power output) of riding a typical mountain bike cross-country course under race conditions. We were particularly interested in determining whether physiological measures relative to mass were better predictors of race performance than absolute measures. Eleven A-grade male cross-country mountain bike riders (VO2max 67.1 +/- 3.6 ml x kg(-1) x min(-1)) performed 2 tests: a laboratory-based maximum progressive exercise test, and a 15.5-km (six 2.58-km laps) mountain bike cross-country time trial. There were significant differences among the speed, cadence, and power output measured in each of 8 different terrain types found in the cross-country time trial course. The highest average speed was measured during the 10-15% downhill section (22.7 +/- 2.6 km x h(-1)), whereas the cadence was highest in the posttechnical flat sections (74.3 +/- 5.6 rpm) and lowest on the 15-20% downhill sections (6.4 +/- 12.1 rpm). The highest mean heart rate (HR) was obtained during the steepest (15-20% incline) section of the course (179 +/- 8 b x min(-1)), when the power output was greatest (419.8 +/- 39.7 W). However, HR remained elevated relative to power output in the downhill sections of the course. Physiological measures relative to total rider mass correlated more strongly to average course speed than did absolute measures (peak power relative to mass r = 0.93, p < 0.01, vs. peak power r = 0.64, p < 0.05; relative VO2max r = 0.80, p < 0.05, vs. VO2max r = 0.66, p < 0.05; power at anaerobic threshold relative to mass r = 0.78, p < 0.05, vs. power at anaerobic threshold r = 0.5, p < 0.05). This suggests that mountain bike cross-country training programs should focus upon improving relative physiological values rather than focusing upon maximizing absolute values to improve performance.     

The effects of intermittent warm-up on 7-9 year-old boys.

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 VO2max, and raised rectal temp. by 0.52 +/- 0.19 degrees 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. VO2max (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.     

Oxygen consumption and metabolic strain in rowing ergometer exercise

Oxygen consumption (VO2) when rowing was determined on a mechanically braked rowing ergometer (RE) with an electronic measuring device. VO2 was measured by an open spirometric system. The pneumotachograph valve was fixed to the sliding seat, thus reducing movement artefacts. A multi-stage test was performed, beginning with a work load of 150 W and increasing by 50 W every 2 minutes up to exhaustion. Serum lactate concentrations were determined in a 30 s break between the work stages. 61 examinations of oarsmen performing at maximum power of 5 W X kg-1 or more were analysed VO2 and heart rate (HR) for each working stage were measured and the regression line of VO2 on the work load (P) and an estimation error (Sxy) were calculated: VO2 = 12.5 X P + 415.2 (ml X min-1) (Sxy = +/- 337 ml, r = 0.98) Good reproducibility was found in repeated examinations. Similar spiroergometry was carried out on a bicycle ergometer (BE) with 10 well trained rowers and 6 trained cyclists. VO2 of rowing was about 600 ml X min-1 higher than for bicycling in the submaximal stages for both groups. The VO2max of RE exercise was 2.6% higher than for oarsmen on BE, and the cyclists reached a greater VO2 on BE than the oarsmen. No differences were found between RE and BE exercise heart rate. The net work efficiency when rowing was 19% for both groups, experienced and inexperienced: when cycling it was 25% for cyclists and 23% for oarsmen.     

Physiological profiles and performance predictors of a women's NCAA rowing team

We described the physiological profiles of rowers (N = 16; age = 20.1 +/- 1.4 years, weight = 78.6 +/- 9.5 kg, height = 177.5 +/- 3.1 cm) of the top 2 varsity boats on an NCAA women's crew and determined whether physiological measures predict boat assignment as determined by the head coach. Eight participants were members of the top varsity boat (1V) and 8 competed at a lower level (2V). Expired gases were collected while subjects completed the U.S. National Team VO(2)max (3-minute stages) and 2 kilometer (2K) time trial rowing ergometer protocols. Heart rates (HR) and blood lactates were measured before, during, and after each test. The VO(2)max and blood lactate at stage 2 of the VO(2)max test were used to predict boat assignment. Average (+/-SD) VO(2)max was 3.86 +/- 0.40 L.min(-1). The 2K times averaged 453.0 +/- 10.5 seconds. Subjects used approximately 96% of VO(2)max and 98% of HR(max) during the 2K time trials. Neither VO(2)max nor submaximal lactate were related to boat assignment. The VO(2) values during the 2K trial indicated that rowing economy differed among athletes. Results of physiological measures should help the coach individualize workouts of top performers.     

Massive insulin secretion in response to anaerobic exercise in exercise-induced hyperinsulinism.

Exercise-induced hyperinsulinism (EIHI) is a recently described entity characterised by recurrent episodes of hypoglycaemia induced by physical exercise. The index patient for this disorder and a matched control were subjected to aerobic and anaerobic exercise tests on a cycle ergometer. Aerobic exercise was performed at an intensity of 60% of the respective 4 mmol/l lactate threshold (40 min). Anaerobic exercise with an intensity corresponding to 130% VO2max lead to exertion within 2-3 min and elicited comparable maximal lactate levels in both subjects (10-11 mmol/l). The patient experienced a massive increase in insulin from 34 to 649 mU/l after the anaerobic test, and a lower increase in insulin from 27 to 79 mU/l during the aerobic test. Insulin concentration remained unchanged during both tests in the control. Epinephrine increased in the EIHI patient, which was probably a counterregulatory response to hypoglycaemia. The activity of lactate dehydrogenase of the index patient in isolated leukocytes as well as the response to inhibition of oxamate was normal. The hypothesis of abnormal transport or metabolism of lactate/pyruvate in the beta-cells of patients with EIHI was further supported by the parallel increase of lactate and insulin in this study elicited in particular by anaerobic exercise.     

Association of the muscle-specific creatine kinase (CKMM) gene polymorphism with physical performance of athletes

The aim of the study was to investigate allele and genotype distributions of the muscle-specific creatine kinase gene (CKMM) A/G polymorphism in athletes (n = 384) and controls (n = 1116), and to find interrelation between genotypes and aerobic capacity in rowers (n = 85). Genotyping was performed by restriction fragment length polymorphism analysis. Aerobic capacity (maximal oxygen consumption (VO2(max)) and maximal power production capacity (W(max was determined using an incremental test to exhaustion by rower ergometer. The frequencies of CKMM A allele and AA genotype were significantly higher in endurance-oriented athletes (n = 176) than in controls (A allele: 78.7% vs. 65.4%; p < 0.0001; AA genotype: 59.7% vs. 44.2%; p = 0.0003). On the other hand, GG genotype was more prevalent in weightlifters (n = 74) in comparison with controls (31.1% vs. 13.4%; p = 0.0001). Furthermore, CKMM AA genotype was associated with high values of VO2(max) (AA - 58.98 (3.44) ml/kg/min, GA - 56.99 (4.36) ml/kg/min, GG - 52.87 (4.32) ml/kg/min, p = 0.0097). Thus, CKMM gene A/G polymorphism is associated with physical performance of athletes.     

No effect of menstrual cycle phase and oral contraceptive use on endurance performance in rowers

The aim of this study was to examine whether variables commonly used in aerobic exercise testing are influenced by menstrual cycle phases and use of oral contraceptive (OC) in female rowers. Twenty-four eumenorrheic female rowers distinguished on the basis of both menstrual status and athleticism participated in this study and were divided into competitive cyclic athletes (n = 8), recreationally trained cyclic athletes (n = 7), and recreationally trained athletes taking OC pills (ROC; n = 9). Rowers performed 2 incremental tests to voluntary exhaustion on a rowing ergometer during 2 different phases of the menstrual cycle: the follicular phase (FP) and the luteal phase (LP). The study variables were power output (Pa), heart rate (HR), oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), the mean respiratory exchange ratio, and ventilatory equivalents of O2 (VE/VO2)) and CO2 (VE/VCO2), which were measured at maximal and at the aerobic-anaerobic transition intensities. In addition, maximal blood lactate (La) values after the test were obtained. When comparing Pa, &OV0312;o2, HR, and La values, no significant differences (p > 0.05) between FP and LP at maximal load and at threshold intensity were found in all 3 groups of the rowers studied. However, we observed higher values (p < 0.05) for VE/VCO2 at both intensities in LP compared with FP in the ROC group. In conclusion, sport-specific endurance performance was not influenced by the phase of the normal menstrual cycle and the synthetic menstrual cycle of the OC users in the rowers studied. Therefore, normally menstruating female rowers and female rowers taking OC pills should not be concerned about the timing of their menstrual cycle with regard to optimized sport-specific endurance performance.     

Effect of prior exercise on maximal short-term power output in humans

The effect of prior exercise (PE) on subsequent maximal short-term power output (STPO) was examined during cycling exercise on an isokinetic ergometer. In the first series of experiments the duration of PE at a power output equivalent to 98% maximum O2 uptake (VO2max) was varied between 0.5 and 6 min before measurement of maximal STPO. As PE duration increased subsequent STPO fell to approximately 70% of control values after 3-6 min. In series ii the effect of varying the intensity of PE of fixed 6-min duration was studied in five subjects. After PE less than 60% VO2max there was an increase of 12% in STPO, but after greater than 60% VO2max there was a progressive fall in STPO as PE intensity increased, indicating a reduction of approximately 35% at 100% VO2max compared with control values. In series iii we examined the effect on STPO of allowing a recovery period after a fixed intensity (mean = 87% VO2max) of 6 min PE before measurement of STPO. This indicated a rapid recovery of dynamic function with a half time of approximately 32 s, which is similar to the kinetics of PC resynthesis and taken with the other findings suggests the dominant role that PC exerts on the STPO under these conditions.     

Endurance training in humans: aerobic capacity and structure of skeletal muscle

The adaptation of muscle structure, power output, and mass-specific rate of maximal O2 consumption (VO2max/Mb) with endurance training on bicycle ergometers was studied for five male and five female subjects. Biopsies of vastus lateralis muscle and VO2max determinations were made at the start and end of 6 wk of training. The power output maintained on the ergometer daily for 30 min was adjusted to achieve a heart rate exceeding 85% of the maximum for two-thirds of the training session. It is proposed that the observed preferential proliferation of subsarcolemmal vs. interfibrillar mitochondria and the increase in intracellular lipid deposits are two possible mechanisms by which muscle cells adapt to an increased use of fat as a fuel. The relative increase of VO2max/Mb (14%) with training was found to be smaller by more than twofold than the relative increase in maximal maintained power (33%) and the relative change in the volume density of total mitochondria (+40%). However, the calculated VO2 required at an efficiency of 0.25 to produce the observed mass-specific increase in maximal maintained power matched the actual increase in VO2max/Mb (8.0 and 6.5 ml O2 X min-1 X kg-1, respectively). These results indicate that despite disparate relative changes the absolute change in aerobic capacity at the local level (maintained power) can account for the increase in aerobic capacity observed at the general level (VO2max).     

Effect of beta-blockade on the drift in O2 consumption during prolonged exercise

The effect of beta-adrenergic blockade on the drift in O2 consumption (VO2 drift) typically observed during prolonged constant-rate exercise was studied in 14 healthy males in moderate heat at 40% of maximal O2 consumption (VO2max). After an initial maximum cycle ergometer test to determine the subjects' control VO2max, subjects were administered each of three medications: placebo, atenolol (100 mg once daily), and propranolol (80 mg twice daily), in a randomized double-blind fashion. Each medication period was 5 days in length and was followed by a 4-day washout period. On the 3rd day of each medication period, subjects performed a maximal cycle ergometer test. On the final day of each medication period, subjects exercised at 40% of their control VO2max for 90 min on a cycle ergometer in a warm (31.7 +/- 0.3 degrees C) moderately humid (44.7 +/- 4.7%) environment. beta-Blockade caused significant (P less than 0.05) reductions in VO2max, maximal minute ventilation (VEmax), maximal heart rate (HRmax), and maximal exercise time. Significantly greater decreases in VO2max, VEmax, and HRmax were associated with the propranolol compared with the atenolol treatment. During the 90-min submaximal rides, beta-blockade significantly reduced heart rate. Substantially lower values for O2 consumption (VO2) and minute ventilation (VE) were observed with propranolol compared with atenolol or placebo. Furthermore, VO2 drift and HR drift were observed under atenolol and placebo conditions but not with propranolol. Respiratory exchange ratio decreased significantly over time during the placebo and atenolol trials but did not change during the propranolol trial.(ABSTRACT TRUNCATED AT 250 WORDS)     

Muscle metabolism during 30, 60 and 90 s of maximal cycling on an air-braked ergometer.

This study examined the anaerobic and aerobic contributions to muscle metabolism during high intensity short duration exercise. Six males [mean (SD): age 25.0 (6.0) years, height 179.0 (8.2) cm, mass 70.01 (7.42) kg, VO2max 4.63 (0.53) l.min-1, body fat 12.7 (2.3)%] performed three counterbalanced treatments of 30, 60 and 90 s of maximal cycling on an air-braked ergometer. All treatments were also performed on days when biopsies were not taken from the vastus lateralis muscle and cannulae not inserted into a forearm vein to ascertain whether these procedures adversely affected performance. The mean results can be summarised as follows: (Table: see text). The muscle lactate and O2 deficit data suggested that 60 and 90 s were more appropriate durations than 30 s for assessing the anaerobic capacity on an air-braked cycle ergometer. The mean power outputs also indicated that the invasive procedures did not adversely affect performance [corrected].     

Ammonia production following maximal exercise: treadmill vs. bicycle testing.

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.