Relationship between perceived exertion during exercise and subsequent recovery measurements.

The return towards resting homeostasis in the post-exercise period has the potential to represent the internal training load of the preceding exercise bout. However, the relative potential of metabolic and autonomic recovery measurements in this role has not previously been established. Therefore the aim of this study was to investigate which of 4 recovery measurements was most closely associated with Borg's Rating of Perceived Exertion (RPE), a measurement widely acknowledged as an integrated measurement of the homeostatic stress of an exercise bout. A heterogeneous group of trained and untrained participants (n = 36) completed a bout of exercise on the treadmill (3 km at 70% of maximal oxygen uptake) followed by 1 hour of controlled recovery. Expired respiratory gases and heart rate (HR) were measured throughout the exercise and recovery phases of the trial with recovery measurements used to calculate the magnitude of excess post-exercise oxygen consumption (EPOCMAG), the time constant of the EPOC curve (EPOCτ), 1 min heart rate recovery (HRR60s) and the time constant of the HR recovery curve (HRRτ) for each participant. RPE taken in the last minute of exercise was significantly associated with HRR60s (r=-0.69), EPOCτ (r=0.52) and HRRτ (r=0.43) but not with EPOCMAG. This finding suggests that, of the 4 recovery measurements under investigation, HRR60s shows modest potential to represent inter-individual variation in the homeostatic stress of a standardized exercise bout, in a group with a range of fitness levels.

Predictors of individual adaptation to high-volume or high-intensity endurance training in recreational endurance runners.

The aim of this study was to investigate factors that can predict individual adaptation to high-volume or high-intensity endurance training. After the first 8-week preparation period, 37 recreational endurance runners were matched into the high-volume training group (HVT) and high-intensity training group (HIT). During the next 8-week training period, HVT increased their running training volume and HIT increased training intensity. Endurance performance characteristics, heart rate variability (HRV), and serum hormone concentrations were measured before and after the training periods. While HIT improved peak treadmill running speed (RSpeak ) 3.1 ± 2.8% (P < 0.001), no significant changes occurred in HVT (RSpeak : 0.5 ± 1.9%). However, large individual variation was found in the changes of RSpeak in both groups (HVT: -2.8 to 4.1%; HIT: 0-10.2%). A negative relationship was observed between baseline high-frequency power of HRV (HFPnight ) and the individual changes of RSpeak (r = -0.74, P = 0.006) in HVT and a positive relationship (r = 0.63, P = 0.039) in HIT. Individuals with lower HFP showed greater change of RSpeak in HVT, while individuals with higher HFP responded well in HIT. It is concluded that nocturnal HRV can be used to individualize endurance training in recreational runners.

High-intensity endurance training increases nocturnal heart rate variability in sedentary participants.

The effects of endurance training on endurance performance characteristics and cardiac autonomic modulation during night sleep were investigated during two 4-week training periods. After the first 4-week training period (3 x 40 min per week, at 75% of HRR) the subjects were divided into HIGH group (n = 7), who performed three high-intensity endurance training sessions per week; and CONTROL group (n = 8) who did not change their training. An incremental treadmill test was performed before and after the two 4-week training periods. Furthermore, nocturnal RR-intervals were recorded after each training day. In the second 4-week training period HIGH group increased their VO2max (P = 0.005) more than CONTROL group. At the same time, nocturnal HR decreased (P = 0.039) and high-frequency power (HFP) increased (P = 0.003) in HIGH group while no changes were observed in CONTROL group. Furthermore, a correlation was observed between the changes in nocturnal HFP and changes in VO2max during the second 4-week training period (r = 0.90, P < 0.001). The present study showed that the increased HFP is related to improved VO2max in sedentary subjects suggesting that nocturnal HFP can provide a useful method in monitoring individual responses to endurance training.

Heart rate variability in prediction of individual adaptation to endurance training in recreational endurance runners.

The aim of this study was to investigate whether nocturnal heart rate variability (HRV) can be used to predict changes in endurance performance during 28 weeks of endurance training. The training was divided into 14 weeks of basic training (BTP) and 14 weeks of intensive training periods (ITP). Endurance performance characteristics, nocturnal HRV, and serum hormone concentrations were measured before and after both training periods in 28 recreational endurance runners. During the study peak treadmill running speed (Vpeak ) improved by 7.5 ± 4.5%. No changes were observed in HRV indices after BTP, but after ITP, these indices increased significantly (HFP: 1.9%, P=0.026; TP: 1.7%, P=0.007). Significant correlations were observed between the change of Vpeak and HRV indices (TP: r=0.75, P<0.001; HFP: r=0.71, P<0.001; LFP: r=0.69, P=0.01) at baseline during ITP. In order to lead to significant changes in HRV among recreational endurance runners, it seems that moderate- and high-intensity training are needed. This study showed that recreational endurance runners with a high HRV at baseline improved their endurance running performance after ITP more than runners with low baseline HRV.

Neuromuscular adaptations during combined strength and endurance training in endurance runners: maximal versus explosive strength training or a mix of both.

This study compared the effects of mixed maximal strength and explosive strength training with maximal strength training and explosive strength training combined with endurance training over an 8-week training intervention. Male subjects (age 21-45 years) were divided into three strength training groups, maximal (MAX, n = 11), explosive (EXP, 10) and mixed maximal and explosive (MIX, 9), and a circuit training control group, (CON, 7). Strength training one to two times a week was performed concurrently with endurance training three to four times a week. Significant increases in maximal dynamic strength (1RM), countermovement jump (CMJ), maximal muscle activation during 1RM in MAX and during CMJ in EXP, peak running speed (S (peak)) and running speed at respiratory compensation threshold (RCT(speed)) were observed in MAX, EXP and MIX. Maximal isometric strength and muscle activation, rate of force development (RFD), maximal oxygen uptake [Formula: see text] and running economy (RE) at 10 and 12 km hr(-1) did not change significantly. No significant changes were observed in CON in maximal isometric strength, RFD, CMJ or muscle activation, and a significant decrease in 1RM was observed in the final 4 weeks of training. RE in CON did not change significantly, but significant increases were observed in S (peak), RCT(speed) and [Formula: see text] Low volume MAX, EXP and MIX strength training combined with higher volume endurance training over an 8-week intervention produced significant gains in strength, power and endurance performance measures of S (peak) and RCT(speed), but no significant changes were observed between groups.

Endurance performance and nocturnal HRV indices.

The effects of endurance training on endurance performance characteristics and cardiac autonomic modulation during night sleep were investigated. Twenty-four sedentary subjects trained over four weeks two hours per week at an average running intensity of 76+/-4% of their heart rate reserve. The R to R ECG-intervals were recorded and heart rate variability indices including high frequency power (HFP) were calculated for the nights following the training days every week. The subjects were divided into responders and non-responders according to the improvements in the maximal velocity of the incremental treadmill test (v(max)). The responders improved their v(max) by 10.9+/-46 % (p < 0.001) while no changes were observed in the non-responders (1.6+/-3.0%), although there were no differences in any training load variables between the groups. In the responders nocturnal HFP was significantly higher during the fourth training week compared to the first training week (p=0.036). Furthermore, a significant correlation was observed between the change in v(max) and the change in nocturnal HFP (r=0.482, p=0.042). It was concluded that after similar training, an increase in cardiac vagal modulation was related to improved v(max) in the sedentary subjects.

Effects of moderate and heavy endurance exercise on nocturnal HRV.

This study examined the effects of endurance exercise on nocturnal autonomic modulation. Nocturnal R-R intervals were collected after a rest day, after a moderate endurance exercise and after a marathon run in ten healthy, physically active men. Heart rate variability (HRV) was analyzed as a continuous four-hour period starting 30 min after going to bed for sleep. In relation to average nocturnal heart rate after rest day, increases to 109+/-6% and 130+/-11% of baseline were found after moderate endurance exercise and marathon, respectively. Standard deviation of R-R intervals decreased to 90+/-9% and 64+/-10%, root-mean-square of differences between adjacent R-R intervals to 87+/-10% and 55+/-16%, and high frequency power to 77+/-19% and 34+/-19% of baseline after moderate endurance exercise and marathon, respectively. Also nocturnal low frequency power decreased to 56+/-26% of baseline after the marathon. Changes in nocturnal heart rate and HRV suggest prolonged dose-response effects on autonomic modulation after exercises, which may give useful information on the extent of exercise-induced nocturnal autonomic modulation and disturbance to the homeostasis.

Strength training in endurance runners.

This study examined effects of periodized maximal versus explosive strength training and reduced strength training, combined with endurance training, on neuromuscular and endurance performance in recreational endurance runners. Subjects first completed 6 weeks of preparatory strength training. Then, groups of maximal strength (MAX, n=11), explosive strength (EXP, n=10) and circuit training (C, n=7) completed an 8-week strength training intervention, followed by 14 weeks of reduced strength training. Maximal strength (1RM) and muscle activation (EMG) of leg extensors, countermovement jump (CMJ), maximal oxygen uptake (VO(2MAX)), velocity at VO(2MAX) (vVO(2MAX)) running economy (RE) and basal serum hormones were measured. 1RM and CMJ improved (p<0.05) in all groups accompanied by increased EMG in MAX and EXP (p<0.05) during strength training. Minor changes occurred in VO(2MAX), but vVO(2MAX) improved in all groups (p<0.05) and RE in EXP (p<0.05). During reduced strength training 1RM and EMG decreased in MAX (p<0.05) while vVO(2MAX) in MAX and EXP (p<0.05) and RE in MAX (p<0.01) improved. Serum testosterone and cortisol remained unaltered. Maximal or explosive strength training performed concurrently with endurance training was more effective in improving strength and neuromuscular performance and in enhancing vVO (2MAX) and RE in recreational endurance runners than concurrent circuit and endurance training.

Multidimensional analysis of metabolism contributions involved in running track tests.

It is difficult to interpret the training induced changes in middle-distance running, since numerous aerobic and anaerobic determinants of the performance are interdependent. Several aerobic and anaerobic tests are available but their results, particularly those from anaerobic tests, may be discordant, not providing univocal interpretation of training. The purpose of this study is to use a multidimensional approach to distinguish aerobic and anaerobic capacities assessed by two running tests on a track: the maximal anaerobic running test (MART) and V(O2max) tests. Eleven runners carried out two maximal tests on a synthetic track before and after a 4-week training period: (i) a maximal test to determine V(O2max), the velocity associated with V(O2max) (vV(O2max)) and the velocity at the lactate threshold (v(LT)), (ii) a maximal anaerobic running test to estimate anaerobic capacity. An all-out test run at v(LT)+50% of the difference between v(LT) and vV(O2max), known to be affected by both aerobic and anaerobic energy production, was used to test this approach. A principal components analysis (PCA) shows that two components (i.e., aerobic and anaerobic) explained 79% of the variation in the physiological variables. The PCA suggests that V(O2max) and MART tests assess the aerobic and the anaerobic capacities, respectively. In contrast, the performance in the all-out test is affected by both aerobic and anaerobic energy production. The PCA shows that v(LT) and DeltaP (difference between the maximal power of the MART and V(O2max)) are clear markers of the long-term endurance and the anaerobic capacity, respectively. This multidimensional approach can be a useful way to disentangle the aerobic and anaerobic components of track tests.

Explosive-strength training improves 5-km running time by improving running economy and muscle power.

To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and 8 control (C) endurance athletes trained for 9 wk. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed (V20 m), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART (VMART) and maximal oxygen uptake (VO2 max). The 5K time, RE, and VMART improved (P < 0.05) in E, but no changes were observed in C. V20 m and 5J increased in E (P < 0.01) and decreased in C (P < 0.05). VO2 max increased in C (P < 0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 wk of training correlated (P < 0.05) with the changes in RE [O2 uptake (r = -0.54)] and VMART (r = 0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in their VO2 max. This improvement was due to improved neuromuscular characteristics that were transferred into improved VMART and running economy.

EMG activities and ground reaction forces during fatigued and nonfatigued sprinting.

The present study was designed to investigate EMG activities and ground reaction forces during fatigued and nonfatigued running. Ten male sprint runners volunteered to run a maximal 20-m speed test, a 400-m time trial, and submaximal 20-m runs at the average speed of the first 100 m of the 400 m. During the latter stage of each run, ground reaction forces and EMG activity of four leg muscles were recorded. EMG activities were time averaged during three phases of running: preactivation, braking, and propulsion phase. The resultant ground reaction forces both in the braking (P < 0.001) and in the propulsion phase (P < 0.01) were greater in the maximal and submaximal 20 m than at the end of the 400 m. The averaged EMG during the braking phase (P < 0.01) and during the total ground phase (P < 0.05) was smaller in the submaximal 20 m than at the end of the 400 m. On the other hand the averaged EMG was greater during the maximal 20 m than at the end of the 400 m during the propulsion phase (P < 0.001) and during the total ground phase (P < 0.05). In addition, the more the preactivity increased the less the resultant ground reaction force decreased in the braking phase during the 400 m run (r = 0.77, P < 0.05). It was concluded that the role of the increased neural activation was to compensate for muscular fatigue and the preactivation had an important role in maintaining force production during the 400-m run. In addition, the fatigue was different in each working muscle.

Neuromuscular characteristics and muscle power as determinants of 5-km running performance.

PURPOSE: The purpose of this study was to investigate neuromuscular characteristics and muscle power as determinants of distance running performance. METHODS: Seventeen male endurance athletes performed a 5-km time trial (5K) that included three separate constant-velocity 200-m laps during the course and a maximal 20-m speed (V20m) test on an indoor track, and running economy (RE) tests on a treadmill and on the track. Maximal anaerobic (MART) and aerobic running tests on the treadmill were used to determine maximal velocity in the MART (VMART), maximal oxygen uptake (VO2max), peak treadmill performance (VO2max demand), and respiratory compensation threshold (RCT). RESULTS: Velocity in the 5K (V5K) correlated positively (P < 0.05) with VO2max, VO2max demand, RCT, and RE, as well as with V20m and VMART. Regression analysis showed that RCT, track RE, and VMART were the most important determinants of V5K. V5K also correlated (P < 0.05) with contact times (CT) and stride rates in the maximal 20-m run (r = -0.49 and 0.58, respectively), as well as with the mean CT of the constant velocity laps during the 5K (r = -0.50). VMART correlated significantly with peak blood lactate concentration in MART (r = 0.59, P < 0.05), V20m (r = 0.87, P < 0.001), and CT in the maximal 20-m run (r = -0.61, P < 0.01). CONCLUSIONS: We conclude that neuromuscular characteristics and VMART were related to 5-km running performance in well trained endurance athletes. Relationships between VMART and neuromuscular and anaerobic characteristics suggest that VMART can be used as a measure of muscle power in endurance athletes.

Aerobic characteristics, oxygen debt and blood lactate in speed endurance athletes during training.

Aerobic characteristics, oxygen debt and blood lactate were analysed in 20 male speed endurance athletes (400 m sprinters and 400 m hurdlers). The subjects were tested three times; at the beginning of March, at the end of May and at the end of August. Aerobic and anaerobic threshold and maximal oxygen uptake measured on the treadmill decreased (p < 0.05-0.01) from the second test occasion to the third one. The anaerobic work test on the treadmill was a constant load test at 5.56 m.s-1 with a slope of 4 degrees. The time to exhaustion increased (p < 0.05) from the first test occasion (112 +/- 17 s) to the second one (136 +/- 35 s) and did not change in the last test (135 +/- 25 s). Following the anaerobic work test oxygen debt was measured during 20 minutes. The highest total oxygen debt values (144 +/- 19 ml.kg-1) were observed in the second test occasion. Peak blood lactate following the anaerobic work increased (p < 0.05) from the first test occasion to the second one and remained at the same level during the next three competitive months. The good speed endurance athletes differed from the poor counterparts in time to exhaustion (p < 0.01), in 100 m record time (p < 0.01) and in maximal oxygen uptake (p < 0.05). Our results suggest that aerobic characteristics decrease during the competitive period in speed endurance athletes. The anaerobic performance capacity including work time and peak blood lactate is at high level in the competitive period.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatigue during a 5-km running time trial.

This study investigated fatigue-induced changes in neuromuscular and stride characteristics during and immediately after the 5-km running time trial. Eighteen well-trained male distance runners performed a maximal 20-m sprint test and maximal voluntary contraction (MVC) in a leg press machine before and immediately after the 5-km running time trial. In all the tests the EMG of five lower limb muscles was measured. The results of the present study showed that muscle fatigue measured in maximal exercises like 20-m sprint and MVC are not related to the fatigue induced changes during the 5-km time trial. The fatigue in the 20-m sprint test was related to the maximal 20-m pretest velocity (r=0.58, p<0.05), but the velocity loss during the 5-km time trial was inversely related to 5-km performance (r= - 0.60, p<0.05) and training volume (r= - 0.58, p<0.05). It was concluded that the fatigue in 5-km running measured pre- and postexercise at maximal effort is more related to sprint performance rather than endurance performance, but the fatigue measured during the 5-km running is related to endurance performance and factors affecting pacing strategy.

Factors related to top running speed and economy.

The main purpose of the present study was to investigate the relationships between running mechanics, top running speed and economy in young endurance athletes. Twenty five endurance athletes (age 19.8 +/- 1.1 years, stature 1.82 +/- 0.07 m and body mass 69.4 +/- 7.5 kg) performed two separate tests on an indoor track. The first test was 8 x 30 m with increasing speed, and the second test was incremental 5 - 6 x 1,000 m. In the first test, ground reaction forces and stride characteristics were measured from each running speed. In the second test, running economy at the speed of 3.89 m . s (-1) and maximal oxygen uptake were determined. Ground contact time was the only factor which correlated significantly with both running economy (r = 0.49, p < 0.05) and maximal running speed (r = - 0.52, p < 0.01). Furthermore, maximal running speed was correlated significantly with the mass-specific horizontal force (r = 0.56, p < 0.01) but not with the vertical effective force. It is concluded that the short contact times required in economical and high speed running suggests that fast force production is important for both economical running and high top running speed in distance runners.

Concurrent endurance and explosive type strength training improves neuromuscular and anaerobic characteristics in young distance runners.

To study effects of concurrent explosive strength and endurance training on aerobic and anaerobic performance and neuromuscular characteristics, 13 experimental (E) and 12 control (C) young (16 - 18 years) distance runners trained for eight weeks with the same total training volume but 19% of the endurance training in E was replaced by explosive training. Maximal speed of maximal anaerobic running test and 30-m speed improved in E by 3.0 +/- 2.0% (p < 0.01) and by 1.1 +/- 1.3% (p < 0.05), respectively. Maximal speed of aerobic running test, maximal oxygen uptake and running economy remained unchanged in both groups. Concentric and isometric leg extension forces increased in E but not in C. E also improved (p < 0.05) force-time characteristics accompanied by increased (p < 0.05) rapid neural activation of the muscles. The thickness of quadriceps femoris increased in E by 3.9 +/- 4.7% (p < 0.01) and in C by 1.9 +/- 2.0% (p < 0.05). The concurrent explosive strength and endurance training improved anaerobic and selective neuromuscular performance characteristics in young distance runners without decreases in aerobic capacity, although almost 20% of the total training volume was replaced by explosive strength training for eight weeks. The neuromuscular improvements could be explained primarily by neural adaptations.

Time course of anaerobic and aerobic energy expenditure during short-term exhaustive running in athletes.

The aim of the present study was to investigate the time course of aerobic and anaerobic energy yield during supramaximal exhaustive running on the treadmill in sprint and endurance athletes. In addition, the relationships between O2 deficit, excess post-exercise O2 consumption (EPOC) and peak post-exercise blood lactate concentration (peak BLa) values were examined, Oxygen uptake during the exhaustive run and 15 min recovery period was measured using a breath-by-breath method. The accumulated O2 deficit was calculated by an extrapolation procedure. Total running time was the same for eight male sprint runners (49.5 +/- 6.0s) and for six male endurance athletes (49.4 +/- 5.3 s). The sprint group had significantly higher O2 deficit (p < 0.01) during the run as well as higher peak BLa (p < 0.05) and EPOC (p < 0.01) after the run than the endurance group. The relative contribution of anaerobic energy yield decreased from 80% to 60% during the first 15 s of the exhaustive run in both groups. The VO2 peaked and was almost unchanged from 25th to 40th s of the run in both groups, although only 79% of their VO2max was attained. The relative contribution of aerobic energy yield was significantly higher (p < 0.05) in the endurance (54-63%) than in the sprint group (43-47%) during the second half of the run. No correlation was found between the O2 deficit and EPOC but peak BLa correlated significantly (p < 0.05) with the O2 deficit (r = 0.53) and EPOC (r = 0.53). In conclusion, the energy release of the sprint and endurance athletes was different only during the second half of the exhaustive supramaximal run, when the sprinters used more the anaerobic and endurance athletes aerobic pathways for energy production.

Acclimatization to altitude and normoxic training improve 400-m running performance at sea level.

To investigate the benefits of 'living high and training low' on anaerobic performance at sea level, eight 400-m runners lived for 10 days in normobaric hypoxia in an altitude house (oxygen content = 15.8%) and trained outdoors in ambient normoxia at sea level. A maximal anaerobic running test and 400-m race were performed before and within 1 week of living in the altitude house to determine the maximum speed and the speeds at different submaximal blood lactate concentrations (3, 5, 7, 10 and 13 mmol x l(-1)) and 400-m race time. At the same time, ten 400-m runners lived and trained at sea level and were subjected to identical test procedures. Multivariate analysis of variance indicated that the altitude house group but not the sea-level group improved their 400-m race time during the experimental period (P < 0.05). The speeds at blood lactate concentrations of 5-13 mmol x l(-1) tended to increase in the altitude house group but the response was significant only at 5 and 7 mmol x l(-1) (P < 0.05). Furthermore, resting blood pH was increased in six of the eight altitude house athletes from 0.003 to 0.067 pH unit (P < 0.05). The results of this study demonstrate improved 400-m performance after 10 days of living in normobaric hypoxia and training at sea level. Furthermore, the present study provides evidence that changes in the acid-base balance and lactate metabolism might be responsible for the improvement in sprint performance.

Effect of hyperoxia on metabolic responses and recovery in intermittent exercise.

The aim of the present study was to investigate whether the breathing of hyperoxic gas affects hemoglobin oxygen saturation (S(a)O(2)) and blood acidosis during intense intermittent exercise and recovery in sprint runners. The hypothesis was that the breathing of hyperoxic gas prevents S(a)O(2) from decreasing, delays blood acidosis during the exercise and improves the rate of heart rate recovery after the exercise. Nine sprinters ran three sets of 300 m at different velocities on a treadmill in normoxia (NOX) and in two hyperoxic conditions (ERHOX and RHOX; F(I)O(2) 0.40) in a randomized order. In ERHOX the inspired air was hyperoxic during the entire exercise and recovery and in RHOX the hyperoxic air was only inhaled during recovery periods. Blood pH and S(a)O(2) were measured from fingertip blood samples taken after each set of runs. The mean heart rate for the final 15 s of the last run in each set (HR(work)), the mean heart rate for the final 15 s of the first minute of recovery (HR(rec)) and the difference of HR(work) and HR(rec) (HR(dec)) were determined. In NOX, S(a)O(2) decreased from 95.0 +/- 2.0% to 88.7 +/- 2.0% (p < 0.001) but S(a)O(2) did not change in ERHOX (from 95.4 +/- 1.3% to 95.9 +/- 1.8%). A significant correlation was observed between the S(a)O(2) decrease in NOX and the effect of hyperoxia on blood pH in ERHOX (r = 0.63) and on HRdec in both ERHOX (r = 0.74) and RHOX (r = 0.69). We concluded that hemoglobin oxygen de-saturation occurred during intensive intermittent exercise in normoxia but hyperoxic gas during the exercise prevents S(a)O(2) from decreasing. Furthermore, the present results suggested that the beneficial effects of hyperoxia on heart rate recovery and blood acidosis during intensive intermittent exercise were related to hemoglobin de-saturation in normoxia.

Muscle power factors and VO2max as determinants of horizontal and uphill running performance.

This study was carried out to investigate the importance of maximal oxygen uptake (VO2max) and so-called muscle power factors relating to neuromuscular and anaerobic characteristics as determinants of peak horizontal and uphill treadmill running velocity (Vmax). Muscle power factors were measured as peak velocity (VMART) and blood lactate concentration (BlaMART) in a maximal anaerobic running test and as maximal 30-m run velocity (V30m). Seven middle-distance runners, eight triathletes and eight cross-country skiers performed an incremental VO2max-test at horizontal (subscript max0) and 7 degrees uphill (subscript max7) and the MART at 3 degrees uphill on a treadmill and V30m-test on a track. The MART consisted of n x 20-s runs with a 100-s recovery between the runs and the velocity was increased by 0.41 m x s(-1) for each consecutive run until exhaustion. At 0 degrees Vmax was significantly higher but VO2max, ventilation and Bla were significantly lower than at 7 degrees inclination. Vmax0 correlated with VMART (r=0.85, P<0.001), Blamax0 (r=0.49, P<0.05) and V30m (r=0.78, P<0.001) but not with VO2max0. Vmax7 correlated with VO2max7 (r=0.78, P<0.001), VMART (r=0.61, P<0.01) and V30m (r=0.53, P<0.05). VMART correlated with BlaMART (r=0.71, P<0.01) and V30m (r=0.96, P<0.001) but not with VO2max0 or VO2max7. Middle-distance runners had a significantly (P<0.001) higher Vmax0, VMART BlaMART and V30m than triathletes and cross-country skiers, but no significant differences were found between the three groups in VO2max0, VO2max7 or Vmax7. We conclude that so-called muscle power factors, e.g. VMART, V30m and BlaMART, contribute to peak treadmill running performance and especially to horizontal running performance and that VO2max contributes more to uphill than horizontal running performance.