Excess postexercise oxygen consumption is unaffected by the resistance and aerobic exercise order in an exercise session

The main purpose of this study was to compare the magnitude and duration of excess postexercise oxygen consumption (EPOC) after 2 exercise sessions with different exercise mode orders, resistance followed by aerobic exercise (R-A); aerobic by resistance exercise (A-R). Seven young men (19.6 ± 1.4 years) randomly underwent the 2 sessions. Aerobic exercise was performed on a treadmill for 30 minutes (80-85% of reserve heart rate). Resistance exercise consisted of 3 sets of 10 repetition maximum on 5 exercises. Previous to the exercise sessions, V(O2), heart rate, V(CO2), and respiratory exchange rate (RER) were measured for 15 minutes and again during recovery from exercise for 60 minutes. The EPOC magnitude was not significantly different between R-A (5.17 ± 2.26 L) and A-R (5.23 ± 2.48 L). Throughout the recovery period (60 minutes), V(O2) and HR values were significantly higher than those observed in the pre-exercise period (p < 0.05) in both exercise sessions. In the first 10 minutes of recovery, V(CO2) and RER declined to pre-exercise levels. Moreover, V(CO2) and RER values in A-R were significantly lower than in R-A. In conclusion, the main result of this study suggests that exercise mode order does not affect the EPOC magnitude and duration. Therefore, it is not necessary for an individual to consider the EPOC when making the decision as to which exercise mode is better to start a training session.     

Time to exhaustion and time spent at a high percentage of VO2max in severe intensity domain in children and adults

The aim of the study was to compare time spent at a high percentage of VO2max (>90% of VO2max) (ts90%), time to achieve 90% of VO2max (ta90%), and time to exhaustion (TTE) for exercise in the severe intensity domain in children and adults. Fifteen prepubertal boys (10.3 ± 0.9 years) and 15 men (23.5 ± 3.6 years) performed a maximal graded exercise to determine VO2max, maximal aerobic power (MAP) and power at ventilatory threshold (PVTh). Then, they performed 4 constant load exercises in a random order at PVTh plus 50 and 75% of the difference between MAP and PVTh (PΔ50 and PΔ75) and 100 and 110% of MAP (P100 and P110). VO2max was continuously monitored. The P110 test was used to determine maximal accumulated oxygen deficit (MAOD). No significant difference was found in ta90% between children and adults. ts90% and TTE were not significantly different between children and adults for the exercises at PΔ50 and PΔ75. However, ts90% and TTE during P100 (p < 0.05 and p < 0.01, respectively) and P110 (p < 0.001) exercises were significantly shorter in children. Children had a significantly lower MAOD than adults (34.3 ± 9.4 ml · kg vs. 53.6 ± 11.1 ml · kg). A positive relationship (p < 0.05) was obtained between MAOD and TTE values during the P100 test in children. This study showed that only for intensities at, or higher than MAP, lower ts90% in children was linked to a reduced TTE, compared to adults. Shorter TTE in children can partly be explained by a lower anaerobic capacity (MAOD). These results give precious information about exercise intensity ranges that could be used in children's training sessions. Moreover, they highlight the implication of both aerobic and anaerobic processes in endurance performances in both populations.     

Comparison of incremental and steady state tests of endurance training

To compare the results obtained by incremental or constant work load exercises in the evaluation of endurance conditioning, a 20-week training programme was performed by 9 healthy human subjects on the bicycle ergometer for 1 h a day, 4 days a week, at 70-80% VO2max. Before and at the end of the training programme, (1) the blood lactate response to a progressive incremental exercise (18 W increments every 2nd min until exhaustion) was used to determine the aerobic and anaerobic thresholds (AeT and AnT respectively). On a different day, (2) blood lactate concentrations were measured during two sessions of constant work load exercises of 20 min duration corresponding to the relative intensities of AeT (1st session) and AnT (2nd session) levels obtained before training. A muscle biopsy was obtained from vastus lateralis at the end of these sessions to determine muscle lactate. AeT and AnT, when expressed as % VO2max, increased with training by 17% (p less than 0.01) and 9% (p less than 0.05) respectively. Constant workload exercise performed at AeT intensity was linked before training (60% VO2max) to a blood lactate steady state (4.8 +/- 1.4 mmol.l-1) whereas, after training, AeT intensity (73% VO2max) led to a blood lactate accumulation of up to 6.6 +/- 1.7 mmol.l-1 without significant modification of muscle lactate (7.6 +/- 3.1 and 8.2 +/- 2.8 mmol.kg-1 wet weight respectively). It is concluded that increase in AeT with training may reflect transient changes linked to lower early blood lactate accumulation during incremental exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acute effect of two aerobic exercise modes on maximum strength and strength endurance

The purpose of this study was to evaluate the effects of 2 modes of aerobic exercise (continuous or intermittent) on maximum strength (1 repetition maximum, 1RM) and strength endurance (maximum repetitions at 80% of 1RM) for lower- and upper-body exercises to test the acute hypothesis in concurrent training (CT) interference. Eight physically active men (age: 26.9 +/- 4.2 years; body mass: 82.1 +/- 7.5 kg; height: 178.9 +/- 6.0 cm) were submitted to: (a) a graded exercise test to determine V(.-)O2max (39.26 +/- 6.95 ml x kg(-1) x min(-1)) and anaerobic threshold velocity (3.5 mmol x L(-1)) (9.3 +/- 1.27 km x h(-1)); (b) strength tests in a rested state (control); and (c) 4 experimental sessions, at least 7 days apart. The experimental sessions consisted of a 5-kilometer run on a treadmill continuously (90% of the anaerobic threshold velocity) or intermittently (1:1 minute at V(.-)O2max). Ten minutes after the aerobic exercise, either a maximum strength or a strength endurance test was performed (leg press and bench press exercises). The order of aerobic and strength exercises followed a William's square distribution to avoid carryover effects. Results showed that only the intermittent aerobic exercise produced an acute interference effect on leg strength endurance, decreasing significantly (p < 0.05) the number of repetitions from 10.8 +/- 2.5 to 8.1 +/- 2.2. Maximum strength was not affected by the aerobic exercise mode. In conclusion, the acute interference hypothesis in concurrent training seems to occur when both aerobic and strength exercises produce significant peripheral fatigue in the same muscle group.     

Relative importance of aerobic and anaerobic energy release during short-lasting exhausting bicycle exercise

Anaerobic energy release is of great importance for shortlasting exercise but has been difficult to quantify. In order to determine the amount of anaerobic energy release during shortlasting exercise we let 17 healthy young males exercise on the ergometer bike to exhaustion. The power during exercise was kept constant and selected to cause exhaustion in approximately 30 s, 1 min, or 2-3 min. The O2 uptake was measured continuously during the exercise, and the anaerobic energy release was quantified by the accumulated O2 deficit. The work done as well as the total energy release rose linearly with the exercise duration and was therefore a sum of a component proportional to time plus a constant addition. The accumulated O2 deficit increased from 1.86 +/- 0.07 (SE) mmol/kg for 30 s exercise to 2.25 +/- 0.06 mmol/kg for 1 min exercise and further to 2.42 +/- 0.08 mmol/kg for exercise lasting 2 min or more (P less than 0.01). The accumulated O2 uptake increased linearly with the duration, and as a consequence of this the relative importance of aerobic processes increased from 40% at 30 s duration to 50% at 1 min duration and further to 65% for exercise lasting 2 min. These results show that both aerobic and anaerobic processes contribute significantly during intense exercise lasting from 30 s to 3 min.     

The effect of pedal rate and time of day on the time to exhaustion from high-intensity exercise

The aim of this study was to examine the supposed influence of pedal rate on the diurnal fluctuation of the time to exhaustion from high-intensity exercise. Eleven male cyclists performed three tests at 06:00 h and three at 18:00 h at a free pedal rate (FPR) and two imposed pedal rates (80% and 120% of the FPR). They performed the tests until exhaustion using a power output corresponding to 95% maximal power (Pmax). Time to exhaustion, rectal temperature, oxygen consumption (.VO2), M. quadriceps, vastus medialis, M. biceps femoris electromyographic Root Mean Square activity rise (RMS slope), and blood lactate concentration were measured. The mean time to exhaustion recorded at 18:00 h (270.6+/-104.8 sec) was greater than at 06:00 h (233.9+/-84.9 sec). The time to exhaustion was significantly greater when the pedal rate was imposed at 80% versus 120% FPR. The blood lactate concentration and absolute core temperature at the point of exhaustion were significantly higher during tests done at 18:00 h. There was no diurnal variation in core temperature increase, .VO2, and RMS slope. The time-of-day effect for every variable did not depend on pedal rate. Diurnal variations in maximal aerobic endurance cannot be explained by a change in aerobic metabolism or in muscular fatigue. The origin of the diurnal variation in the time to exhaustion is likely to lie in greater participation in anaerobic metabolism. Also, the influence of temperature on neuromuscular functioning as an explanation for the diurnal variation in performance cannot be excluded in this study. The hypothesis on the basis of which pedal rate would influence diurnal variations in time to exhaustion in cycling was not validated by this research.     

Oxygen consumption following exercise of moderate intensity and duration.

To study the effects of exercise intensity and duration on excess postexercise oxygen consumption (EPOC), 8 men [age = 27.6 (SD 3.8) years, VO2max = 46.1 (SD 8.5) ml min-1 kg-1] performed four randomly assigned cycle-ergometer tests (20 min at 60% VO2max, 40 min at 60% VO2max, 20 min at 70% VO2max, and 40 min at 70% VO2max). O2 uptake, heart rate and rectal temperature were measured before, during, and for 1 h following the exercise tests. Blood for plasma lactate measurements was obtained via cannulae before, and at selected times, during and following exercise. VO2 rapidly declined to preexercise levels following each of the four testing sessions, and there were no differences in EPOC between the sessions. Blood lactate and rectal temperature increased (P < 0.05) with exercise, but had returned to preexercise levels by 40 min of recovery. The results indicate that VO2 returned to resting levels within 40 min after the end of exercise, regardless of the intensity (60% and 70% VO2max) or duration (20 min and 40 min) of the exercise, in men with a moderate aerobic fitness level.     

Oxygen deficit is related to the exercise time to exhaustion at maximal aerobic speed in middle distance runners

The purpose of this study was to show the relationship between oxygen deficit and the time to exhaustion (tlim) at maximal aerobic speed (MAS). The minimum speed that elicits VO(2max) was assumed to be the maximal aerobic speed (MAS). Fourteen subelite male runners (mean (SD: age = 27 +/- 5 yrs: VO(2max) = 68.9 +/- 4.6 ml kg (-1). min ( -1); MAS = 21.5 +/- 1 km h (-1) ) participated in the study. Each subject performed an incremental test to determine and MAS. The subjects ran to exhaustion at velocities corresponding to 100 and 120 % MAS. Oxygen deficit was measured during the period exercise to exhaustion at 120% of MAS and was calculated from the difference between O(2) demand and the accumulated O 2 uptake. The tlim values at 100% MAS were correlated with the values of tlim at 120% MAS (r = 0.52). The results reveal that the oxygen deficit was related to the time to exhaustion at MAS and indicate that the greater the oxygen deficit, the greater the time to exhaustion at MAS. It was also noted that the adjustment of oxygen consumption is related to the oxygen deficit. In other words, the subjects who have an important anaerobic capacity are the most efficient during an exercise time to exhaustion at MAS. The time limit values can be expressed by a linear regression making intervene MAS and anaerobic capacity. This conclusion could be of great interest in the training of middle distance runners.     

The effect of citrate loading on exercise performance, acid-base balance and metabolism

Nine subjects (VO2max 65 +/- 2 ml.kg-1.min-1, mean +/- SEM) were studied on two occasions following ingestion of 500 ml solution containing either sodium citrate (C, 0.300 g.kg-1 body mass) or a sodium chloride placebo (P, 0.045 g.kg-1 body mass). Exercise began 60 min later and consisted of cycle ergometer exercise performed continuously for 20 min each at power outputs corresponding to 33% and 66% VO2max, followed by exercise to exhaustion at 95% VO2max. Pre-exercise arterialized-venous [H+] was lower in C (36.2 +/- 0.5 nmol.l-1; pH 7.44) than P (39.4 +/- 0.4 nmol.l-1; pH 7.40); the plasma [H+] remained lower and [HCO3-] remained higher in C than P throughout exercise and recovery. Exercise time to exhaustion at 95% VO2max was similar in C (310 +/- 69 s) and P (313 +/- 74 s). Cardiorespiratory variables (ventilation, VO2, VCO2, heart rate) measured during exercise were similar in the two conditions. The plasma [citrate] was higher in C at rest (C, 195 +/- 19 mumol.l-1; P, 81 +/- 7 mumol.l-1) and throughout exercise and recovery. The plasma [lactate] and [free fatty acid] were not affected by citrate loading but the plasma [glycerol] was lower during exercise in C than P. In conclusion, sodium citrate ingestion had an alkalinizing effect in the plasma but did not improve endurance time during exercise at 95% VO2max. Furthermore, citrate loading may have prevented the stimulation of lipolysis normally observed with exercise and prevented the stimulation of glycolysis in muscle normally observed in bicarbonate-induced alkalosis.     

Effects of short-term training using powercranks on cardiovascular fitness and cycling efficiency

Powercranks use a specially designed clutch to promote independent pedal work by each leg during cycling. We examined the effects of 6 wk of training on cyclists using Powercranks (n=6) or normal cranks (n=6) on maximal oxygen consumption (VO2max) and anaerobic threshold (AT) during a graded exercise test (GXT), and heart rate (HR), oxygen consumption (VO2), respiratory exchange ration (RER), and gross efficiency (GE) during a 1-hour submaximal ride at a constant load. Subjects trained at 70% of VO2max for 1 h.d(-1), 3 d.wk(-1), for 6 weeks. The GXT and 1-hour submaximal ride were performed using normal cranks pretraining and posttraining. The 1-hour submaximal ride was performed at an intensity equal to approximately 69% of pretraining VO2max with VO2, RER, GE, and HR determined at 15-minute intervals during the ride. No differences were observed between or within groups for VO2max or AT during the GXT. The Powercranks group had significantly higher GE values than the normal cranks group (23.6 +/- 1.3% versus 21.3 +/- 1.7%, and 23.9 +/- 1.4% versus 21.0 +/- 1.9% at 45 and 60 min, respectively), and significantly lower HR at 30, 45, and 60 minutes and VO2 at 45 and 60 minutes during the 1-hour submaximal ride posttraining. It appears that 6 weeks of training with Powercranks induced physiological adaptations that reduced energy expenditure during a 1-hour submaximal ride.     

Excess postexercise oxygen consumption following acute aerobic and resistance exercise in women who are lean or obese

Seventeen women were divided into lean (19.5 +/- 0.5 years; 22.2 +/- 0.6 kg.m(-2)) and obese (20.4 +/- 0.5 years; 34.9 +/- 2.1 kg.m(-2)) groups. On completion of a submax cycle ergometer test and 10-repetition maximum (10RM) of 5 exercises on a Smith machine, subjects returned for 2 exercise sessions during menses. Session 1 consisted of performing 3 sets of 10 repetitions at 70% of the predetermined 10RM for the following exercises: squat, calf raises, bench press, upright row, and shoulder press. Session 2 consisted of cycling at 60-65% VO2max for a duration that would expend the same number of calories as the resistance session. Postexercise respiratory exchange ratio and EPOC magnitude/duration were similar for both groups. These findings indicate that women who are lean or obese will respond similarly to exercise at similar relative intensities and that aerobic and resistance exercise of equal caloric expenditure will elicit similar EPOC responses.     

Fat-free mass and excess post-exercise oxygen consumption in the 40 minutes after short-duration exhaustive exercise in young male Japanese athletes

The relationship between fat-free mass (FFM) and excess post-exercise oxygen consumption (EPOC) has not been well researched because of the relatively small number of subjects studied. This study investigated the effects of FFM on EPOC and EPOC/maximum oxygen consumption. 250 Japanese male athletes between 16 and 21 years old from Nagasaki prefecture had their EPOC measured up to 40 minutes after short-duration exhaustive exercise. The value was named as EPOC40 min. The proportions of EPOC up to 1, 3, 6, 10, and 25 minutes to EPOC40 min were calculated and named as P1, P3, P6, P10, and P25, respectively. Body size and composition, VO2max and resting metabolic rate (RMR) were also measured. Mean EPOC40 min was 9.04 L or 158 ml/kg FFM. EPOC40 min was related to FFM (r=0.55, p<0.001) and VO2max (r=0.37, p<0.001). The ratio of EPOC40 min to VO2max was related to FFM (r=0.28, p<0.001). P1, P3, P6, P10, and P25 were negatively related to EPOC40 min/FFM, EPOC40 min/VO2max, and FFM. Athletes who had larger FFM had larger EPOC40 40 min and EPOC40 40 min/VO2max, and smaller P1, P3, P10, and P25.     

Consumption of an oral carbohydrate-protein gel improves cycling endurance and prevents postexercise muscle damage

Investigators have reported improved endurance performance and attenuated post-exercise muscle damage with carbohydrate-protein beverages (CHO+P) versus carbohydrate-only beverages (CHO). However, these benefits have been demonstrated only when CHO+P was administered in beverage-form, and exclusively in male subjects. Thus, the purposes of this study were to determine if an oral CHO+P gel improved endurance performance and post-exercise muscle damage compared to a CHO gel, and determine if responses were similar between genders. Thirteen cyclists (8 men, 5 women; VO(2)peak = 57.9 +/- 7.0 ml x kg(-1) x min(-1)) completed two timed cycle-trials to volitional exhaustion at 75% of VO(2)peak. At 15-minute intervals throughout these rides, subjects received CHO or CHO+P gels, which were matched for carbohydrate content (CHO = 0.15 g CHO x kg BW(-1); CHO+P = 0.15 g CHO + 0.038 g protein x kg BW(-1)). Trials were performed using a randomly counterbalanced, double-blind design. Subjects rode 13% longer (p < 0.05) when utilizing the CHO+P gel (116.6 +/- 28.5 minutes) versus the CHO gel (102.8 +/- 25.0 minutes). In addition, men (101.8 +/- 24.6; 114.8 +/- 26.2) and women (104.4 +/- 28.6; 119.6 +/- 34.9) responded similarly to the CHO and CHO+P trials, with no significant treatment-by-gender effect. Postexercise creatine kinease (CK) was not significantly different between treatments. However, CK increased significantly following exercise in the CHO trial (183 +/- 116; 267 +/- 214 U x L(-1)), but not the CHO+P trial (180 +/- 133; 222 +/- 141 U x L(-1)). Therefore, to prolong endurance performance and prevent increases in muscle damage, it is recommended that male and female cyclists consume CHO+P gels rather than CHO gels during and immediately following exercise.     

Effects of oral propranolol and exercise protocol on indices of aerobic function in normal man

The exercise responses to two different progressive, upright cycle ergometer tests were studied in nine healthy, young subjects either with no drug (ND) or following 48 h or oral propranolol (P) (40 mg q.i.d.). The ergometer tests increased work rate by 30 W either every 30 s or every 4 min. Propranolol caused a significant (p less than 0.05) reduction in peak oxygen uptake (VO2) during both the 30-s and 4-min tests (30-s ND, 3949 +/- 718 mL X min-1 (means +/- SD); 30-s P, 3408 +/- 778 mL X min-1; 4-min ND, 4058 +/- 409 mL X min-1; 4-min P, 3725 +/- 573 mL X min-1). There was no difference between 30-s ND and 4-min ND for peak VO2. The ventilatory anaerobic threshold was not significantly different between any test (30-s ND, 2337 +/- 434 mL O2 X min-1; 30-s P, 2174 +/- 406 mL O2 X min-1; ND, 2433 +/- 685 mL O2 X min-1; 4-min P, 2296 +/- 604 mL O2 X min-1). The VO2 at which blood lactate had increased by 0.5 mM above resting levels was significantly lower than the ventilatory anaerobic threshold for the 4-min ND (1917 +/- 489) and the 4-min P (1978 +/- 412) tests, but was not different for the 30-s ND and 30-s P tests. At exhaustion in the progressive tests, the blood PCO2 was higher (p less than 0.05) in both 30-s tests than 4-min tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxygen uptake kinetics and time to exhaustion in cycling and running: a comparison between trained and untrained subjects

The objective of the present study was to compare pulmonary gas exchange kinetics (VO2 kinetics) and time to exhaustion (Tlim) between trained and untrained individuals during severe exercise performed on a cycle ergometer and treadmill. Eleven untrained males in running (UR) and cycling (UC), nine endurance cyclists (EC), and seven endurance runners (ER) were submitted to the following tests on separate days: (i) incremental test for determination of maximal oxygen uptake (VO2max) and the intensity associated with the achievement of VO2max (IVO2max) on a mechanical braked cycle ergometer (EC and UC) and on a treadmill (ER and UR); (ii) all-out exercise bout performed at IVO2max to determine the time to exhaustion at IVO2max (Tlim) and the time constant of oxygen uptake kinetics (tau). The tau was significantly faster in trained group, both in cycling (EC = 28.2 +/- 4.7s; UC = 63.8 +/- 25.0s) and in running (ER = 28.5 +/- 8.5s; UR = 59.3 +/- 12.0s). Tlim of untrained was significantly lower in cycling (EC = 384.4 +/- 66.6s vs. UC; 311.1 +/- 105.7 s) and higher in running (ER = 309.2 +/- 176.6 s vs. UR = 439.8 +/- 104.2 s). We conclude that the VO2 kinetic response at the onset of severe exercise, carried out at the same relative intensity is sensitive to endurance training, irrespective of the exercise type. The endurance training seems to differently influence Tlim during exercise at IVO2max in running and cycling.     

Panax notoginseng supplementation enhances physical performance during endurance exercise

The purpose of this study was to investigate whether a single 1,350-mg dose of Panax notoginseng (PNG) could enhance aerobic capacity, endurance, and mean blood pressure (MAP) in young adults. We randomly assigned 29 untrained adults, aged 20-35 years, to an experimental (EXP, n = 13) or a control (CON, n = 16) group. For 30 days, the EXP took 1,350 mg per day of PNG capsule and the CON consumed 1,350 mg per day of starch capsule. Measurement variables were taken before and after 30 days of either PNG supplement or placebo. Results show that the EXP improved (p < 0.05) their endurance time by >7 minutes, and lowered (p < 0.05) maximal MAP (from 113 +/- 12 to 109 +/- 14 mm Hg) and Vo2 at the 24th minute (from 32.5 +/- 8 to 27.6 +/- 8 ml.kg-1.min-1) during endurance cycle exercise. Based on this study, we conclude that 1,350 mg per day PNG supplement for 30 days improved endurance time to exhaustion, and lowered MAP and Vo2 during endurance exercise.     

Does aerobic and strength exercise sequence in the same session affect the oxygen uptake during and postexercise?

Concurrent training is a strategy employed in both general fitness and sports conditioning. The purpose of this study was to compare the responses of VO2 in different combinations of strength exercise with aerobic interval exercise. Eight men (23.6 ± 4.2 years, 178 ± 6.3 cm, 77 ± 7.9 kg, 7.67 ± 1.95% body fat) completed 3 combinations of strength training (ST) and aerobic training (AT) in a randomized order with a 7-day recovery period: AT before ST exercises, AT between 2 blocks of ST exercises, and AT after ST exercises. The ST comprised 4 exercises performed in 3 sets of 10 reps and 2 exercises, abdominal crunch and lumbar extension, performed in 3 sets of 30 and 20 reps, respectively. The AT consisted of a 20-minute interval cycling. There were no significant differences in the values of absolute or relative VO2, in the heart rate (HR) and in the respiratory exchange ratio (RER) when the 3 sessions (during + postexercise measurements) were compared (values are mean ± SD). Analyzing only ST in each session, differences were detected in the RER values (F = 4.714; p < 0.05; η2 = 0.308) between AT before ST and AT in the middle of ST (1.01 ± 0.97 vs. 1.11 ± 0.07, respectively). In all sequences, there was a significant increase (p < 0.05) in the values of relative and absolute VO2 and HR, and a significant decrease in RER values (p < 0.05) from the first to the second part of the ST session. The values of absolute or relative VO2, HR, and RER did not vary significantly among the 3 sessions as compared with the AT after ST. These data support the hypothesis that ST and AT, when performed in sequence in the same session, do not seem to affect the overall oxygen consumption during the exercise session. Therefore, training sessions may incorporate both modalities without apparent impact on aerobic exercise.     

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.     

Is postexercise hypotension related to excess postexercise oxygen consumption through changes in leg blood flow?

After a single bout of aerobic exercise, oxygen consumption remains elevated above preexercise levels [excess postexercise oxygen consumption (EPOC)]. Similarly, skeletal muscle blood flow remains elevated for an extended period of time. This results in a postexercise hypotension. The purpose of this study was to explore the possibility of a causal link between EPOC, postexercise hypotension, and postexercise elevations in skeletal muscle blood flow by comparing the magnitude and duration of these postexercise phenomena. Sixteen healthy, normotensive, moderately active subjects (7 men and 9 woman, age 20-31 yr) were studied before and through 135 min after a 60-min bout of upright cycling at 60% of peak oxygen consumption. Resting and recovery VO2 were measured with a custom-built dilution hood and mass spectrometer-based metabolic system. Mean arterial pressure was measured via an automated blood pressure cuff, and femoral blood flow was measured using ultrasound. During the first hour postexercise, VO2 was increased by 11 +/- 2%, leg blood flow was increased by 51 +/- 18%, leg vascular conductance was increased by 56 +/- 19%, and mean arterial pressure was decreased by 2.2 +/- 1.0 mmHg (all P <0.05 vs. preexercise). At the end of the protocol, VO2 remained elevated by 4 +/- 2% (P <0.05), whereas leg blood flow, leg vascular conductance, and mean arterial pressure returned to preexercise levels (all P >0.7 vs. preexercise). Taken together, these data demonstrate that EPOC and the elevations in skeletal muscle blood flow underlying postexercise hypotension do not share a common time course. This suggests that there is no causal link between these two postexercise phenomena.     

Effect of anaerobic and aerobic exercise of equal duration and work expenditure on plasma growth hormone levels

Growth hormone (GH) and lactic acid levels were measured in five normal males before, during and after two different types of exercise of nearly equal total duration and work expenditure. Exercise I (aerobic) consisted of continuous cycling at 100 W for 20 min. Exercise II (anaerobic) was intermittent cycling for one minute at 285 W followed by two minutes of rest, this cycle being repeated seven times. Significant differences (P less than 0.01) were observed in lactic acid levels at the end of exercise protocols (20 min) between the aerobic (I) and anaerobic (II) exercises (1.96 +/- 0.33 mM X 1(-1) vs 9.22 +/- 0.41 mM X 1(-1), respectively). GH levels were higher in anaerobic exercise (II) than in aerobic (I) at the end of the exercise (20 min) (2.65 +/- 0.95 micrograms X 1(-1) vs 0.8 +/- 0.4 micrograms X 1(-1); P less than 0.10) and into the recovery period (30 min) (7.25 +/- 6.20 micrograms X 1(-1) vs 2.5 +/- 2.9 micrograms X 1(-1); P less than 0.05, respectively).