Metabolic response of endurance athletes to training with added load

Summary Endurance athletes were divided into experimental (n=12) and control (n=12) groups to investigate the effects of extra-load training on energy metabolism during exercise. A vest weighing 9%–10% body weight was worn every day from morning to evening for 4 weeks including every (n=6) or every other (n=6) training session. After 4 weeks the control group had a lower blood lactate concentration during submaximal running, whereas the experimental group had significantly higher blood lactate and oxygen uptake (p<0.01–p<0.05), and a lower 2 mmol lactate threshold (p<0.05) and an increased blood lactate concentration after a short running test to exhaustion (p<0.05). Those experimental subjects (n=6) who used the added load during every training session had a lower 2 mmol lactate threshold, improved running time to exhaustion, improved vertical velocity when running up stairs and an increased during submaximal running after the added load period. It is concluded that the additional loading increased anaerobic metabolism in the leg muscles during submaximal and maximal exercise. An increased recruitment and adaptation of the fast twitch muscle fibres is suggested as the principal explanation for the observed changes.     

The relationship of plasma ammonia and lactate concentrations to perceived exertion in trained and untrained women

Summary The purpose of this study was to investigate the covariance between perceived exertion (recorded using Borg's category-ratio scale CR-10) and the relative oxygen uptake, and lactate and ammonia concentrations in blood from a peripheral vein. Ratings of perceived exertion (RPE) at 25%, 50%, 75% and 90% maximal oxygen uptake and lactate and ammonia concentrations were compared in well-trained women distance runners (n = 22) and untrained women (n = 10). Ammonia concentrations in peripheral venous blood were significantly correlated with RPE (P < 0.05), both in the trained and untrained women. Differences between the trained and untrained subjects occurred when the ammonia concentration increased to 148 mol · l^–1 in both groups investigated; similarly, the mean RPE correlated significantly with the lactate concentration (P < 0.05), both in the trained and untrained women and there was a difference in RPE between groups when lactate concentration in the blood had risen to 4.4 mmol · l^–1. It would seem that the correlation of blood ammonia and lactate concentrations with RPE during exercise could be a useful indicator of the development of fatigue.     

Absence of the predisposing factors and signs and symptoms usually associated with overreaching and overtraining in physical fitness centers

OBJECTIVE:

The aim of this study was to evaluate the occurrence of the well‐known predisposing factors and signs and symptoms usually associated with either overreaching or overtraining syndrome in physical fitness centers in São Paulo City, Brazil.

METHOD:

A questionnaire consisting of 13 question groups pertaining to either predisposing factors (1‐7) or signs and symptoms (8‐13) was given to 413 subjects. The general training schedule of the volunteers was characterized by workout sessions of 2.18 ± 0.04 h for a total of 11.0 ± 0.3 h/week for 33 ± 2 months independent of the type of exercise performed (walking, running, spinning, bodybuilding and stretching). A mean score was calculated ranging from 1 (completely absent) to 5 (severe) for each question group. A low occurrence was considered to be a question group score lower than 4, which was observed in all 13 question groups.

RESULTS:

The psychological evaluation by POMS Mood State Questionnaire indicated a normal non‐inverted iceberg. The hematological parameters, creatine kinase activity, cortisol, total testosterone and free testosterone concentrations were within the normal ranges for the majority of the volunteers selected for this analysis (n  =  60).

CONCLUSION:

According to the questionnaire score analysis, no predisposing factors or signs and symptoms usually associated with either overreaching or overtraining were detected among the members of physical fitness centers in São Paulo City, Brazil. This observation was corroborated by the absence of any significant hematological or stress hormone level alterations in blood analyses of the majority of the selected volunteers (n  =  60).     

Perceptual and physiological responses to cycling and running in groups of trained and untrained subjects

Summary An interesting aspect, when comparing athletes, is the effect ofspecialized training upon both physiological performance and perceptual responses. To study this, four groups (with six individuals each) served as subjects. Two of these consisted of highly specialized individuals (racing cyclists and marathon runners) and the other two of non-specialized individuals (sedentary and all-round trained). Cycling on a cycle ergometer and running on a treadmill were chosen as modes of exercise. Variables measured included heart rate, blood lactate and perceived exertion, rated on two different scales. Results show a linear increase of both heart rate and perceived exertion (rated on the RPE scale) in all four groups, although at different absolute levels. Blood lactate accumulation, during cycling and running, differentiates very clearly between the groups. When heart rate and perceived exertion were plotted against each other, the difference at the same subjective rating (RPE 15) between cycling and running amounted to about 15–20 beats · min^–1 in the non-specialized groups. The cyclists exhibited almost no difference at all as compared to 40 beats · min^–1 for the runners. It can be concluded that specialized training changes both the physiological as well as the psychological response to exercise.     

The use of ratings of perceived exertion for regulating exercise levels in rowing ergometry

The purpose of this study was to examine the validity of the use of ratings of perceived exertion (RPE) to estimate and regulate exercise intensity during rowing ergometry. Nine competitive male rowers [mean age 28.6 years, (SD 6.3)] completed two rowing trials on an ergometer. The first trial (estimation) consisted of an incremental protocol designed to elicit a range of work outputs (WO) and heart rates (HR). The subjects indicated their perception of effort using a 15-point scale at each intensity level. In the second trial (production), 7–14 days later, the subjects were asked to produce exercise intensities corresponding to five levels of RPE: 15,11,17,13, and 19. Data analysis revealed high Pearson correlation coefficients between HR and RPE (r = 0.95,P < 0.01) and WO and RPE (r = 0.96,P < 0.01) during the estimation trial. In addition, significant correlations (P < 0.01) were obtained between the estimation and production trials for HR (r = 0.82) and WO (r = 0.84). Posthoc analysis of variance revealed that the observed differences in mean HR were not significant (P > 0.05) at three of the five intensity levels (RPE 15,17 and 19), but were at the two lowest RPE levels (11 and 13). Significant mean differences in WO were seen at all but RPE 17. These data support the validity of the RPE scale as a measure of physiological strain among competitive male rowers, and offer support for its use as a method of regulating the intensity of rowing ergometry, especially at higher levels.     

Effect of alcohol on perceived exertion in relation to heart rate and blood lactate

Summary The purpose of the study was to determine whether the perception of exertion is affected by alcohol during physical performance and whether altered self-rating of exertion is the result of an altered perception per se or of an altered physical capacity to perform work. Ten healthy men participated. Each subject was his own control and received an alcohol dose corresponding to 1 g · kg^–1 body mass in 40% solution in the experimental session. The exercise test was performed on a cycle ergometer with an initial intensity of 50 W which was increased stepwise by 50 W at 4-min intervals up to near-maximal. The rating of perceived exertion (RPE) did not differ between alcohol and control sessions. Alcohol induced a significant increase in heart rate during exercise at 50 W ( = 8 beats · min^–1) and at 100 W ( = 10 beats · min^–1), while the change at higher intensities was insignificant. The systolic blood pressure and the blood lactate concentration were not significantly changed by alcohol. It is concluded that a moderate dose of alcohol does not alter RPE during physical exercise either per se or secondarily to an altered physical capacity to perform work.     

Does the amount of exercising muscle alter the aerobic demand of dynamic exercise?

The primary purpose of this study was to determine if the aerobic demand for production of specified power outputs is altered by distribution of work between the arms and legs compared with when all the work is performed by the legs. Because of the important exercise training implications, a secondary purpose of this study was to determine if the exercising muscle mass affects the cardiorespiratory demands at specified rating of perceived exertion (RPE) levels and blood lactate concentrations. Nine healthy adults completed leg cycling and combined arm and leg exercise on an Airdyne using a discontinuous protocol. Repeated measures ANOVA revealed that oxygen uptake for the combined arm and leg exercise averaged 0.04 l·min⁻¹ greater (p<0.05) than for leg cycling at the same external power outputs. However, RPE levels at specified power outputs were lower (p<0.05) with combined arm and leg exercise than leg cycling. At specified RPE levels and blood lactate concentrations, oxygen uptake and heart rate values were higher (p<0.05) for combined arm and leg exercise than leg cycling. From these findings we conclude that: (1) the addition of arm exercise to leg cycling results in a reduction in RPE, but a minimal increase in oxygen consumption to perform a given power output, and (2) if training intensity is established by RPE or blood lactate concentration, use of a muscle mass larger than that used in leg cycling should allow a greater cardiorespiratory training effect.     

Perceived exertion related to heart rate and blood lactate during arm and leg exercise

Summary To compare some psychophysiological responses to arm exercise with those to leg exercise, an experiment was carried out on electronically braked bicycle ergometers, one being adapted for arm exercise. Eight healthy males took part in the experiment with stepwise increases in exercise intensity every 4 min: 40—70—100—150—200 W in cycling and 20—35—50—70—100 W in arm cranking. Towards the end of each 4 min period, ratings of perceived exertion were obtained on the RPE scale and on a new category ratio (CR) scale: heart rate (HR) and blood lactate accumulation (BL) were also measured. The responses obtained were about twice as high or more for arm cranking than for cycling. The biggest difference was found for BL and the smallest for HR and RPE. The incremental functions were similar in both activities, with approximately linear increases in HR and RPE and positively accelerating functions for CR (exponents about 1.9) and BL (exponents 2.5 and 3.3 respectively). When perceived exertion (according to the CR scale) was set as the dependent variable and a simple combination of HR and BL was used as the independent variable, a linear relationship was obtained for both kinds of exercise, as has previously been found in cycling, running, and walking. The results thus give support for the following generalization: For exercise of a steady state type with increasing loads the incremental curve for perceived exertion can be predicted from a simple combination of HR and BL. This study was supported by a research grant from The Bank of Sweden Tercentenary Foundation No. 85/291     

Training effect on performance, substrate balance and blood lactate concentration at maximal lactate steady state in master endurance-runners

Training effects on time-to-exhaustion, substrate and blood lactate balances at the maximal lactate steady state velocity (MLSSv) were examined. Eleven male, veteran, long-distance runners performed three tests before and after 6 weeks of training at MLSSv: an incremental test to determine maximum O₂ uptake (O_2,max) and the velocity at the lactate threshold (vLT), a sub-maximal test of two stages of 20 min at 95 and 105% of vLT separated by 40 min rest to determine the MLSSv and the corresponding lactate concentration (MLSSc) and a time-to-exhaustion run at MLSSv for which the substrate balance was calculated. Duration and distance run at MLSSv increased dramatically respectively from 44±10 to 63±12 min and from 10.4 to 15.7 km respectively (P<0.01). MLSSv increased significantly with training but the relative fraction of O_2,max remained the same (85.2±4.5 vs. 85.3±5.2%, P=0.93). MLSSc was unaffected by training as determined from the percentage of energy yielded by carbohydrates (80%) during the exhaustive run at MLSSv. These findings show that training at MLSS elicits small increases in MLSSv and O_2,max, but enhances time-to-exhaustion (endurance) at MLSSv substantially (+50%). Training does not change the proportion of carbohydrate oxidized, which is the major substrate used during an exhaustive run at MLSS lasting 1 h.     

Blood lactate in trained cyclists during cycle ergometry at critical power

Summary The purposes of this investigation were to determine the validity of critical power (CP) as a measure of the work rate that can be maintained for a very long time without fatigue and to determine whether this corresponded with the maximal lactate steady-state (la_ss,max). Eight highly trained endurance cyclists (maximal oxygen uptake 74.1 ml · kg^–1 · min^–1, SD 5.3) completed four cycle ergometer tests to exhaustion at predetermined work rates (360, 425, 480 and 520 W). From these four co-ordinates of work and time to fatigue the regression of work limit on time limit was calculated for each individual (CP). The cyclists were then asked to exercise at their CP for 30 min. If CP could not be maintained, the resistance was reduced minimally to allow the subject to complete the test and maintain a blood lactate plateau. Capillary blood was sampled at 0, 5, 10, 20 and 30 min into exercise for the analysis of lactate. Six of the eight cyclists were unable to maintain CP for 30 min without fatigue. In these subjects, the mean power attained was 6.4% below that estimated by CP. Mean blood lactates (n = 8) reached a steady-state (8.9 mmol · l^–1, SD 1.6) during the last 20 min of exercise indicating that CP slightly overestimated la_{ss, max}. Individual blood lactates during the last 20 min of exercise were more closely related to the y-intercept of the CP curve (r=0.78, P<0.05) than either CP (0.34, NS) or mean power output (r=0.42, NS). The present investigation has shown that highly trained endurance cyclists can tolerate previously unreported levels of blood lactate during 30 min of exercise at or near their CP. Blood lactates during continuous exercise are higher than at the same work rate during an incremental test. The CP provides a simple and inexpensive means of assessing the exercise intensity which can be maintained continuously, while avoiding the methodological difficulties associated with ventilatory and lactate thresholds.     

Validity of heart rate and ratings of perceived exertion as indices of exercise intensity in a group of children while swimming

Summary The purpose of this study was to investigate the validity of heart rate (f _c) and ratings of perceived exertion (RPE) as indices of exercise intensity in a group of children while swimming. Six healthy male swimmers, aged 10–12, swam tethered using the breast-stroke in a flume. The resistance started at 1.0 kg and increased in 1.0 kg steps up to the point of their exhaustion. The subjects swam for 5 min during each period, with a rest of 10–20 min until they had returned to their resting f _c level. The last exercise intensity was with the maximal mass the subjects could support for 2 min. The last min of oxygen consumption (VO₂) and 30 s of f _c were measured during each exercise period. The subjects gave their RPE assessment at the end of exercise.The individual relationships between f _c and VO₂, and percentage maximal oxygen consumption (% VO_2max, were linear with a high correlation r=0.962–0.996 and r=0.962–0.996, respectively. Therefore, it was concluded that f _c was valid as an index of the exercise intensity of children while swimming. Compared to the results found in adults using a similar protocol, the children's f _c were 8.3–26.9 beats·min^–1 higher than those of the adults at the given % VO_2max. The present study showed two different patterns in the relationship between VO₂ and RPE in individuals. In two subjects the RPE increased linearly with VO₂ while in the other four subjects the increase was discontinuous. If f _c and RPE were to be applied to the setting and evaluation of exercise intensity during swimming, it would seem that f _c would be a more useful guide than RPE for some children.     

Hormonal responses in athletes: the use of a two bout exercise protocol to detect subtle differences in (over)training status

In overtrained athletes, several signs and symptoms have been associated with the imbalance between training and recovery. However, reliable diagnostic markers for distinguishing between well-trained, overreached (OR) and overtrained (OT) athletes are lacking. A hallmark feature of overtraining syndrome (OTS) is the inability to sustain intense exercise and recover for the next training or competition session. We therefore devised a test protocol utilizing two bouts of maximal work. With this test protocol we tried to establish a difference in hormonal responses between the training status of T and OR athletes. Seven well-trained cyclists participated in this study and were tested before and after a training camp. We also present the data of one OT motocross athlete who was clinically diagnosed as overtrained. All athletes performed two maximal exercise tests separated by 4 h. Blood was analyzed for cortisol, adrenocorticotrophic hormone (ACTH), growth hormone and prolactin (PRL). Performance decreased by 6% between the first and the second exercise test in the OR group and by 11% in the OT subject. Moreover, during the second exercise test there were more marked differences between the T and OR athletes; in particular, the OT subject did not show an increase in some of the hormonal responses. PRL increased only by 14% in the OT subjects second test and there was a 7% decrease in ACTH. The two exercise approach enables us to detect subtle performance decrements that will not be identified by one exercise trigger. The hormonal responses to the second exercise test were different between the T and OR athletes (the increase in the T group was higher than in the OR that was higher than in the OT). The results of the case presentation of an overtrained athlete provide evidence of an altered and dysfunctional hypothalamic–pituitary axis response to two bouts of maximal exercise. These findings can be used to develop markers for diagnosis of OTS and to begin to address the pathologic mechanism operative in the syndrome, as well as providing an outcome measure to evaluate possible therapeutic regimes.     

Neuromuscular characteristics and fatigue in endurance and sprint athletes during a new anaerobic power test

The purpose of this study was to investigate neuromuscular and energy performance characteristics of anaerobic power and capacity and the development of fatigue. Ten endurance and ten sprint athletes performed a new maximal anaerobic running power test (MARP), which consisted ofn x 20-s runs on a treadmill with 100-s recovery between the runs. Blood lactate concentration [la^–]_b was measured after each run to determine submaximal and maximal indices of anaerobic power (P _3mmol·1 ^–1,P_5mmol·1 ^–1,P_10mmol·1 ^–1andP _max) which was expressed as the oxygen demand of the runs according to the American College of Sports Medicine equation: the oxygen uptake (ml·kg^–1·min^–1)=0.2·velocity (m·min^–1) +0.9·slope of treadmill (frac)·velocity (m·min^–1)+3.5. The height of rise of the centre of gravity of the counter movement jumps before (CMJ_rest) and during (CMJ) the MARP test, as well as the time of force production (t _F) and electromyographic (EMG) activity of the leg muscles of CMJ performed after each run were used to describe the neuromuscular performance characteristics. The maximal oxygen uptake ( _max), anaerobic and aerobic thresholds were determined in the _max test, which consisted ofn x 3-min runs on the treadmill. In the MARP-testP _max did not differ significantly between the endurance [116 (SD 6) ml·kg^–1·min^–1] and sprint [120 (SD 4) ml·kg^–1·min^–1] groups, even though CMJ_rest and peak [la^–]_b were significantly higher and _max was significantly lower in the sprint group than in the endurance group and CMJ_rest height correlated withP _max (r=0.50,P<0.05). The endurance athletes had significantly higher mean values ofP _3mmol·1 ^–1andP _5mmol·1 ^–1[89 (SD 7) vs 76 (SD 8) ml·kg^–1·min^–,P<0.001 and 101 (SD 5) vs 90 (SD 8) ml·kg^–1·min^–1,P<0.01. Significant positive correlations were observed between theP _3mmol·l ^–1and _max, anaerobic and aerobic thresholds. In the sprint group CMJ and the averaged integrated iEMG decreased andt _F increased significantly during the MARP test, while no significant changes occurred in the endurance group. The present findings would suggest thatP _max reflected in the main the lactacid power and capacity and to a smaller extent alactacid power and capacity. The duration of the MARP test and the large number of CMJ may have induced considerable energy and neuromuscular fatigue in the sprint athletes preventing them from producing their highest alactacidP _max at the end of the MARP test. Due to lower submaximal [la^–]_b (anaerobic sprinting economy) the endurance athletes were able to reach almost the sameP _max as the sprint athletes.     

Blood lactate accumulation in intermittent supramaximal exercise

Summary Blood lactate accumulation rate and oxygen consumption have been studied in six trained male runners, aged 20 to 30 years. Subjects ran on a treadmill at a rate representing 172±5% for four 45 s sessions, separated by 9 min rest periods. Oxygen consumption was measured throughout. Blood lactate was determined in samples taken from the ear and was measured at the end of each exercise session, and two, five and nine minutes later. After the fourth exercise session, the same measurements were made every five min for 30 min. 4 subjects repeated a single exercise of the same type, duration and intensity and the same measurements were taken. With repetitive intermittent exercise, gradual increases in blood lactate concentration ([LA]b) occurred, whereas its rate of accumulation ([LA]b) decreased. The amount of oxygen consumed during each 45 s exercise session remained unchanged for a given subject. After cessation of intermittent exercise, the half-time of blood lactate was 26 min, whereas it was only 15 min after a single exercise session. values, on the other hand, returned to normal after 15 to 20 min. All other conditions being equal, the gradual decrease in [LA]b during intermittent exercise could be explained if the lactate produced during the first exercise session is used during the second period, and/or if the diffusion space of lactate increases. The diffusion space seems to be multicompartmental on the basis of half-time values noted for [LA]b after intermittent exercise, compared with those noted after a single exercise session. The distinction between the rapid return to normal values and the more gradual return to normal blood lactate levels confirms that there is no simple and direct relationship between oxygen debt and the accumulation of blood lactate after muscular exercise. In practical terms, these results show that the calorific equivalent of lactic acid defined by Margaria et al. (1963) cannot be used in the case of intermittent exercise of supramaximal intensity.     

The use of critical power as a determinant for establishing the onset of blood lactate accumulation

Eight highly trained male kayakers were studied to determine the relationship between critical power (CP) and the onset of blood lactate accumulation (OBLA). Four exercise sessions of 90 s, 240 s, 600 s, and 1200 s were used to identify the CP of each kayaker. Each individual CP was obtained from the line of best fit (LBF_CP) obtained from the progressive work output/time relationships. The OBLA was identified by the 4 mmol·l^–1 blood lactate concentration and the work output at this level was determined using a lactate curve test. This consisted of paddling at 50 W for 5 min after which a 1-min rest was taken during which a 25-l blood sample was taken to analyse for lactate. Exercise was increased by 50 W every 5 min until exhaustion, with the blood sample being taken in the 1-min rest period. The exercise intensity at the OBLA for each subject was then calculated and this was compared to the exercise intensity at the LBF_CP. The intensity at LBF_CP was found to be significantly higher (t=2.115, P<0.05) than that at the OBLA of 4 mmol·1^–1. These results were further confirmed by significant differences being obtained in blood lactate concentration (t=8.063, P<0.05) and heart rate values (t=2.90, P<0.05) obtained from the exercise intensity at LBF_CP over a 20-min period and that of the anaerobic threshold (Th_an) parameters obtained from the lactate/heart rate curve. These differences suggest that CP and Th_an are different physiological events and that athletes have utilised either one or the other methods for monitoring training and its effects.     

Effect of endurance training on excessive CO2 expiration due to lactate production in exercise

Summary We attempted to determine the change in total excess volume of CO₂ Output (CO₂ excess) due to bicarbonate buffering of lactic acid produced in exercise due to endurance training for approximately 2 months and to assess the relationship between the changes of CO₂ excess and distance-running performance. Six male endurance runners, aged 19–22 years, were subjects. Maximal oxygen uptake (VO_2max), oxygen uptake (VO₂) at anaerobic threshold (AT), CO₂ excess and blood lactate concentration were measured during incremental exercise on a cycle ergometer and 12-min exhausting running performance (12-min ERP) was also measured on the track before and after endurance training. The absolute magnitudes in the improvement due to training for C02 excess per unit of body mass per unit of blood lactate accumulation (Ala^–) in exercise (CO₂ excess·mass^–1·la^–), 12-min ERP, VO₂ at AT (AT-VO₂) and VO_2max on average were 0.8 ml·kg^–1·l^–1·mmol^–1, 97.8m, 4.4 ml·kg^–1· min^–1 and 7.3 ml·kg^–1·min^–1, respectively. The percentage change in CO₂ excess·mass^–1·la^– (15.7%) was almost same as those of VO_2max (13.7%) and AT-VO₂ (13.2%). It was found to be a high correlation between the absolute amount of change in CO₂ excess·mass^–1·la^– and the absolute amount of change in AT-VO₂ (r=0.94, P<0.01). Furthermore, the absolute amount of change in C02 excess·mass^–1·la^–, as well as that in AT-VO₂ (r=0.92, P<0.01), was significantly related to the absolute amount of change in 12-min ERP (r=0.81, P<0.05). It was concluded that a large CO₂ excess·mass^–1·la^–1 of endurance runners could be an important factor for success in performance related to comparatively intense endurance exercise such as 3000–4000 m races.     

Threshold increases in plasma growth hormone in relation to plasma catecholamine and blood lactate concentrations during progressive exercise in endurance-trained athletes

Plasma human growth hormone ([HGH]), adrenaline ([A]), noradrenaline ([NA]) and blood lactate ([La^–]_b) concentrations were measured during progressive, multistage exercise on a cycle ergometer in 12 endurance-trained athletes [aged 32.0 (SEM 2.0) years]. Exercise intensities (3 min each) were increased by 50 W until the subjects felt exhausted. Venous blood samples were taken after each intensity. The [HGH] and catecholamine concentrations increased negligibly during exercise of low to moderate intensities revealing an abrupt rise at the load corresponding to the lactate threshold ([La^–]-T). Close correlations (P < 0.001) were found between [La^–]_b and plasma [HGH] (r = 0.64), [A] (r = 0.71) and [NA] (r = 0.81). The mean threshold exercise intensities for [HGH], [A] and [NA], detected by log-log transformation, [154 (SEM 19) W, 162 (SEM 15) W and 160 (SEM 17) W, respectively] were not significantly different from the [La^–]-T [161 (SEM 12) W]. The results indicated that the threshold rise in plasma [HGH] followed the patterns of plasma catecholamine and blood lactate accumulation during progressive exercise in the endurancetrained athletes.     

Transfer effects of endurance training to exercise with untrained limbs

Summary There has been a controversy over whether the increases in maximal oxygen uptake ( O_{2 max}) and reductions in heart rate at a given submaximal workload after endurance training are limited to exercise with trained limbs or also may be observed during exercise with untrained limbs. In the present study five initially very sedentary young men trained by leg cycling (LT) and five by arm cranking (AT) 30 min per day on 4 days a week for 11 weeks at an intensity 75–80% O_{2 max}. Before and after training the subjects performed submaximal and maximal arm cranking and leg cycling tests. Leg cycling and arm cranking O_{2 max} increased 15% and 9% after LT and 12% and 35% after AT, respectively. Heart rate at a given submaximal workload was lower (p<0.05) during trained and untrained limb exercise following LT and AT. However, subjective ratings of perceived exertion (RPE) at a given submaximal workload were lower (p<0.01) only during exercise with trained limbs after LT and AT. In light of previous findings, the present increases in O_{2 max} and reductions in submaximal exercise heart rate with untrained limbs suggest that the initial fitness of the subjects as well as the intensity, frequency, and duration of training may be important factors in determining the extent to which transfer effects of endurance training can be observed. Although the present data suggest that reductions in RPE after endurance training may be the result of local changes in trained muscles, the possible contribution of central nervous adaptations cannot be excluded.Supported in part by Grant HL 18907 from The National Heart, Lung, and Blood Institute