Comparison of critical swimming velocity and velocity at lactate threshold in elite triathletes

The purpose of this study was to determine whether the critical swimming velocity (Vcrit) corresponds to the velocity at lactate threshold (V-LT) in elite triathletes. Eight elite triathletes (5 male, 3 female; age 26 +/- 4 years; height 1.7 +/- 0.1 m and body mass 75 +/- 4 kg) participated in the study. Vcrit, defined as the speed that could theoretically be maintained indefinitely without exhaustion, was expressed as the slope of a regression line between swimming distance covered and the corresponding times of five time trials over 100, 200, 400, 800 and 1500m and all combinations of these. Lactate threshold (LT) was determined by visual inspection as the point of first inflection of the lactate-work rate curve following 5 x 300 m swims of increasing velocity which were paced using the Aquapacer (Challenge and Response, Inverurie, Scotland). Velocities of the 300 m swims were -10, -5, 0, +5 and +10% of the average 100m pace from a 1500 m time trial. Vcrit was similar regardless of the combination or number of time trials used in the linear regression. For all subjects Vcrit was significantly faster (p <0.05) than V-LT (1.23 +/- 0.11 m x s(-1) and 1.15 +/- 0.10 m x s(-1) respectively). Blood lactate concentrations were also significantly higher (p < 0.05) at Vcrit (3.0 +/- 1.0 mM) than at LT (1.9 +/- 0.4 mM). Results from the present study demonstrate that Vcrit can be calculated from any two time trials in triathletes, however Vcrit did not represent V-LT in triathletes. Since Vcrit is faster than V-LT it is unlikely to be sustained indefinitely and consequently the notion of Vcrit should be re-evaluated in light of these findings.     

Incremental test protocol, recovery mode and the individual anaerobic threshold

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady-state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of IAT following both a submaximal or maximal incremental exercise test. Seven males (VO2max = 57.6 +/- 5.8 ml.kg-1.min -1) did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) and two maximal incremental tests. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one submaximal and one maximal test and active (approximately 35% VO2max) during the other tests. An IAT metabolic rate and power output were calculated for the submax-passive (IATsp, LA = 1.85 +/- 0.42 mmol.l-1), max-passive (IATmp, LA = 3.41 +/- 1.14 mmol.l-1), submax-active (IATsa, LA = 2.13 +/- 0.45 mmol.l-1) and max-active (IATma, LA = 3.44 +/- 0.73 mmol.l-1) protocols. At weekly intervals, the subjects exercised for 30 min at one of the four IAT metabolic rates. Active recovery did not affect the calculation of IAT, but following the maximal incremental tests, IAT occurred at a higher (p less than 0.05) power output, absolute VO2 and %VO2max (71% VO2max) compared with the IAT determined with the submaximal incremental tests (61% VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)     

Off seasonal and pre-seasonal assessment of circulating energy sources during prolonged running at the anaerobic threshold in competitive triathletes

Objectives: To compare changes in circulating energy sources during prolonged exercise in off season (OS) and pre-season (PS) training of triathletes.

Methods: Nine athletes of the Swiss national triathlon team (three female, mean (SD) age 28.7 (4.9) years, height 169.8 (6.0) cm, weight 57.0 (6.2) kg, V^·O₂MAX 66.5 (5.3) ml/min/kg; six male, mean (SD) age 24.0 (4.1) years, height 181.4 (6.9) cm, weight 73.5 (6.0) kg, V^·O₂MAX 75.9 (4.9) ml/min/kg) were tested twice (2.5 months apart) during a 25 km aerobic capacity test run at the end of the OS and just before the season. The average training load during the OS was 9.9 h/week, and this increased to 14.4 h/week in the PS. With heart rates as reference, exercise intensity during the aerobic capacity test was 97.0 (4.9)% of the anaerobic threshold and 91.2 (4.5)% of V^·O₂MAX. Blood samples were collected before, during, and after the aerobic capacity test. Samples were collected every 5 km during three minute rest intervals.

Results: Blood was analysed for triglyceride (TG), free fatty acids, cholesterol, high density lipoprotein cholesterol, glucose, insulin, lactate, and changes in plasma volume. A two factor (season by distance) repeated measures analysis of variance revealed an increase in capacity for prolonged exercise in the PS by a decrease in running intensity during the aerobic capacity test (% of speed at 2.0 mmol/l lactate threshold, p = 0.008), an increase in running speed at the anaerobic threshold (p = 0.003) and at 4.0 and 2.0 mmol/l (p<0.001) of the lactate threshold. A significant season by distance interaction was found for TG (p<0.001). TG concentrations peaked at 5 km and decreased logarithmically throughout the OS (1.48 (0.34) to 0.86 (0.20) mmol/l) and PS (1.90 (0.31) to 0.73 (0.18) mmol/l) tests. From the OS to the PS, there was an increase in the difference in TG at 5–15 km with a concomitant increase at 2.0 mmol/l of the lactate threshold. The peak TG concentrations at 5 km followed by a logarithmic decrease suggest that TG may also provide circulating energy. A greater logarithmic decrease in TG occurred in the PS than in the OS, indicating a higher rate of use. There was an increase in the difference in TG at 5–15 km similar to the increase in the speed at 2.0 mmol/l of the lactate threshold between the two seasons. Glucose, insulin, lactate, and free fatty acids were similar in the two seasons.

Conclusion: Free fatty acid and TG concentrations were much higher than expected, and the two training seasons showed significantly different patterns of TG concentration during prolonged running. These responses may be related to aerobic capacity of prolonged exercise.

     

A perceptive individual time trial performed by triathletes to estimate the anaerobic threshold. A preliminary study

AIM: The aim of the study was to test the ability to estimate the power output (PO) and heart rate (HR) associated with 'anaerobic threshold' levels for triathletes by means of a 30-min perceptive individual time trial (PITT30). METHODS: Thirteen triathletes (8 males and 5 females) performed an incremental exercise test to estimate maximal parameters such as oxygen uptake, power output and heart rate. From this incremental exercise test, the individual anaerobic threshold (IAT) and ventilatory threshold (VT) for all subjects were estimated. Then, the subjects completed a PITT30 at self-selected work intensity on a stationary ergometer equipped with the SRM Training System. Mean values of PO, HR, and pedalling cadence were recorded continuously between the 5th and the 30th min of the test. RESULTS: Significant correlations were observed between the mean PO recorded during PITT30 and PO measured at IAT (r=0.88; p<0.0001) and at VT (r=0.89; p<0.0001). Furthermore, bias and limits of agreement confirm the degree of association between the 3 METHODS: However, PITT30 over-estimated HR values compared to the values obtained at IAT and VT. CONCLUSION: It was concluded that, for triathletes, mean PO measured with PITT30 allows a partial valid estimation of PO associated with 2 known methods of 'anaerobic threshold' determination. The application of PITT30 may offer a useful tool for athletes and coaches to estimate the 'anaerobic threshold' in order to control accurately the training effects.     

Active recovery, endurance training, and the calculation of the individual anaerobic threshold

The individual anaerobic threshold (IAT) is the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of the IAT before and after an endurance training program. Both before and after an 8-wk training program, nine subjects did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) until LA was greater than or equal to 4 mmol.l-1. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one test and active (approximately 35% VO2max) during the second test. An IAT metabolic rate and power output were calculated for the passive (IATp) and active (IATa) recovery protocols. On separate days, before and after training, five of the subjects exercised for 30 min at either the IATp or the IATa. Before training, IATa occurred at a higher (P less than 0.05) power output and absolute and relative VO2 compared to IATp. After training, VO2max and the power output and VO2 at IATa and IATp increased significantly; as a percent VO2max, IATp but not IATa increased. During the pretraining 30-min IAT rides, LA was higher during the IATa than the IATp test, but LA values did not change during the last 20 min of exercise. LA was similar for both 30-min IAT rides after training and did not change from 5 to 30 min of exercise. The LA steady-state concentrations ranged from 1.3 to 6.8 mmol.l-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

A simple method for individual anaerobic threshold as predictor of max lactate steady state

BACKGROUND: The individual anaerobic threshold (IAT) is defined (18) as the highest metabolic rate where blood lactate (La) concentrations are maintained at a steady-state during prolonged exercise. Stegmann et al.'s (18) method to detect IAT, using La-performance relationship during incremental graded exercise, is based on the assumption that La is in relatively steady state by the end of each 3-min stage of work rate. However, at the end of a 3-min stage, an La steady state (Lass) is not reached (13). PURPOSE: The present study was designed to investigate whether the IAT should be determined by attributing La value to the antecedent stage (IATa) or to the same stage of its measurement (IATm), then to verify whether this IAT would be a valid indicator of the max Lass during prolonged exercise. METHODS: Forty-one athletes (21 male and 20 female), regularly involved in different physical training, performed three exercise tests on treadmill. The first one was a 3-min stage incremental test to detect the IATa and IATm. The other two tests were 30-min prolonged tests at the IATa and IATm workload. Lass were present in IATa intensity (about 4.0 mmol x L(-1)) both in male and female athletes, whereas at IATm intensity a Lass was not present and a premature break-off occurred in some cases. DISCUSSION: This protocol can be useful for practical use because: 1) the method of choosing the anaerobic threshold is easy to apply; 2) it does not require to reach the maximal effort; and 3) although in some cases the IATa could probably underestimate the workload of max Lass, the IATa can be regarded as guideline to define the intensity of endurance training.     

Exercise training below and above the lactate threshold in the elderly

In this study we report the effects of training at intensities below and above the lactate threshold on parameters of aerobic function in elderly subjects (age range 65-75 yr). The subjects were randomized into high-intensity (HI, N = 8; 75% of heart rate reserve = approximately 82% VO2max = approximately 121% of lactate threshold) and low-intensity (LI, N = 9; 35% of heart rate reserve = approximately 53% VO2max = approximately 72% of lactate threshold) training groups which trained 4 d.wk-1 for 30 min.session-1 for 8 wk. Before and after the training, subjects performed an incremental exercise test for determination of maximal aerobic power (VO2max) and lactate threshold (LT). In addition, the subjects performed a 6-min single-stage exercise test at greater than 75% of pre-training VO2max (SST-High) during which cardiorespiratory responses were evaluated each minute of the test. After training, the improvements in VO2max (7%) for LI and HI were not different from one another (delta VO2max for LI = 1.8 +/- 0.7 ml.kg-1.min-1; delta VO2max for HI = 1.8 +/- 1.0 ml.kg-1.min-1) but were significantly greater (P = 0.02) than the post-testing change observed in the control group (N = 8). Training improved the LT significantly (10-12%; P less than 0.01) and equally for both LI and HI (delta LT for for LI = 2.3 +/- 0.6 ml O2.kg-1.min-1; delta LT for HI = 1.8 +/- 0.8 ml O2.kg-1.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Step length and individual anaerobic threshold assessment in swimming

Anaerobic threshold is widely used for diagnosis of swimming aerobic endurance but the precise incremental protocols step duration for its assessment is controversial. A physiological and biomechanical comparison between intermittent incremental protocols with different step lengths and a maximal lactate steady state (MLSS) test was conducted. 17 swimmers performed 7×200, 300 and 400 m (30 s and 24 h rest between steps and protocols) in front crawl until exhaustion and an MLSS test. The blood lactate concentration values ([La-]) at individual anaerobic threshold were 2.1±0.1, 2.2±0.2 and 1.8±0.1 mmol.l?-?1 in the 200, 300 and 400 m protocols (with significant differences between 300 and 400 m tests), and 2.9±1.2 mmol.l?-?1 at MLSS (higher than the incremental protocols); all these values are much lower than the traditional 4 mmol.l?-?1 value. The velocities at individual anaerobic threshold obtained in incremental protocols were similar (and highly related) to the MLSS, being considerably lower than the velocity at 4 mmol.l?-?1. Stroke rate increased and stroke length decreased throughout the different incremental protocols. It was concluded that it is valid to use intermittent incremental protocols of 200 and 300 m lengths to assess the swimming velocity corresponding to individual anaerobic threshold, the progressive protocols tend to underestimate the [La-] at anaerobic threshold assessed by the MLSS test, and swimmers increase velocity through stroke rate increases.     

Neuromuscular fatigue and recovery dynamics following prolonged continuous run at anaerobic threshold

Objective

The aim of this study was to determine the influence of intensive aerobic running on some muscle contractile characteristics and the dynamics of their recovery during a 2 hour period afterwards.

Methods

Seven well trained runners performed a 6 km run at anaerobic threshold (V_OBLA). Knee torque during single twitch, low and high frequency electrical stimulation (ES), maximum voluntary knee extension, and muscle activation level test of the quadriceps femoris muscles were measured before and immediately after the run, and at several time points during a 120 minute interval that followed the run.

Results

After exercise, the mean (SE) maximum twitch torque (T_TW) and torque at ES with 20 Hz (low frequency ES; T_F20) dropped by 14.1 (5.1)% (p<0.05) and 20.6 (7.9)% (p<0.05) respectively, while torque at stimulation with 100 Hz (high frequency ES; T_F100), maximum isometric knee extension torque (maximum voluntary contraction torque; T_MVC), and activation level did not change significantly. Twitch contraction time was shortened by 8 (2)% (p<0.05). Ten minutes after the run, T_TW was 40% higher than immediately after the run and 10% (p<0.05) higher than before the run. T_F20, T_F100, and T_MVC remained lower for 60 minutes (p<0.05) than before the run.

Conclusions

A 6 km continuous run at V_OBLA caused peripheral fatigue by impairing excitation–contraction coupling. Twitch torque recovered very quickly. However, the process of torque restoration at maximum isometric knee extension torque and at high and low frequency ES took much longer.     

Lack of concordance amongst measurements of individual anaerobic threshold and maximal lactate steady state on a cycle ergometer

Introduction: The calculation of exertion intensity, in which a change is produced in the metabolic processes which provide the energy to maintain physical work, has been defined as the anaerobic threshold (AT). The direct calculation of maximal lactate steady state (MLSS) would require exertion intensities over a long period of time and with sufficient rest periods which would prove significantly difficult for daily practice. Many protocols have been used for the indirect calculation of MLSS. Objectives: The aim of this study is to determine if the results of measurements with 12 different AT calculation methods and calculation software [Keul, Simon, Stegmann, Bunc, Dickhuth (TKM and WLa), D_max, Freiburg, Geiger-Hille, Log-Log, Lactate Minimum] can be used interchangeably, including the method of the fixed threshold of Mader/OBLA’s 4 mmol/l and then to compare them with the direct measurement of MLSS. Methods: There were two parts to this research. Phase 1: results from 162 exertion tests chosen at random from the 1560 tests. Phase 2: sixteen athletes (n = 16) carried out different tests on five consecutive days. Results: There was very high concordance among all the methods [intraclass correlation coefficient (ICC) > 0.90], except Log-Log in relation to the Stegamnn, D_max, Dickhuth-WLa and Geiger-Hille. The Dickhuth-TKM showed a high tendency towards concordance, with D_max (2.2 W) and Dickhuth-WLa (0.1 W). The Dickhuth-TKM method presented a high tendency to concordance with Dickhuth-WLa (0.5 W), Freiburg (7.4 W), MLSS (2.0 W), Bunc (8.9 W), D_max (0.1 W). The calculation of MLSS power showed a high tendency to concordance, with Dickhuth-TKM (2 W), D_max (2.1 W), Dickhuth-WLa (1.5 W). Conclusion: The fixed threshold of 4 mmol/l or OBLA produces slightly different and higher results than those obtained with all the methods analyzed, including MLSS, meaning an overestimation of power in the individual anaerobic threshold. The Dickhuth-TKM, D_max and Dickhuth-WLa methods defined a high concordance on a cycle ergometer. Dickhuth-TKM, D_max, Dickhuth-WLa described a high concordance with the power calculated to know the MLSS.     

Exercise with the intensity of the individual anaerobic threshold in acute hypoxia

PURPOSE: The aim of the present study was to find out if the determination of the individual anaerobic threshold (IAT) during incremental treadmill tests in normoxia and acute normobaric hypoxia (FiO2 0.15) defines equivalent relative submaximal intensities in these environmental conditions. METHODS: 11 male middle and long distance runners performed a 1-h treadmill run in normoxia and hypoxia at the intensity of the IAT determined in the respective environment with measurement of lactate, glucose, heart rate, catecholamines, ventilatory parameters, and rate of perceived exertion (RPE). RESULTS: During the 1-h treadmill runs, speed was significantly reduced in hypoxia compared with normoxia (12.8 +/- 0.7 vs 14.7 +/- 0.7 km x h(-1)). Relative intensity expressed as a percentage of VO(2max) was similar in both environments (82-83% on the average) and elicited comparable lactate steady states [LaSS, 2.5 +/- 0.7 - 3.4 +/- 1.1 mmol x L(-1) (normoxia), 2.7 +/- 0.8 - 3.6 +/- 1.0 mmol x L(-1) (hypoxia) after 10 and 60 min, respectively] and glucose levels, but significantly reduced heart rate in hypoxia by 5 beats x min(-1) on the average. A steady state was also found for the ventilatory parameters. Plasma epinephrine and norepinephrine levels were similar in both environments. RPE was significantly lower after 40-60 min of exercise in hypoxia. CONCLUSIONS: Relative intensities in normoxia and acute hypoxia are equivalent when endurance exercise is performed with the running speed at the IAT determined in the respective environment. The heart rate-blood lactate relationship, however, is changed in hypoxia and relative submaximal exercise intensity is higher in acute hypoxia when training is performed with similar heart rate as in normoxia.     

Plasma adiponectin response to sculling exercise at individual anaerobic threshold in college level male rowers

The purpose of the investigation was to study plasma adiponectin response to a single exercise session in male rowers. Eight college level, single scull rowers (VO2max: 5.01+/-0.43 l.min-1; age: 21.5+/-4.5 yrs; height: 184.9+/-5.0 cm; body mass: 78.5+/-8.4 kg; body fat: 11.8+/-1.2%) participated in this study. Venous blood samples were obtained before, immediately after, and following the first 30 min of recovery of constant load on-water rowing over a distance of 6.5 km (approximately 30 min) at the individual anaerobic threshold (75.2+/-2.9% of VO2max). Adiponectin was unchanged (p>0.05) immediately after the exercise. However, adiponectin was significantly increased above the resting value after the first 30 min of recovery (+14.7%; p<0.05). Similarly, leptin was unchanged immediately after exercise and was significantly decreased after the first 30 min of recovery (-18.2%; p<0.05). Plasma insulin was significantly reduced immediately after exercise and remained significantly lower during the first 30 min of recovery period. Glucose increased with exercise and returned to the pre-exercise level after the first 30 min of recovery. Basal adiponectin was significantly related to VO2max (r=-0.62; p=0.034). However, there was no relationship between basal adiponectin and other measured variables. Similarly, basal leptin demonstrated no relationship with other measured variables. In conclusion, the results of the present study suggest that plasma adiponectin is sensitive in the first 30 min of recovery to the effects of relatively short-term exercise at individual anaerobic threshold when all major muscle parts are involved.     

Blood lactate during recovery from intense exercise: impact of inspiratory loading

PURPOSE: It has long been suggested that inspiratory muscle activity may impact blood lactate levels ([Lac(-)]B) during the recovery from dynamic exercise. In this study, we tested the hypothesis that inspiratory muscle activation during recovery from intense exercise would contribute to La clearance, thus leading to reduced [Lac(-)]B. METHODS: Twelve healthy men underwent two maximal, incremental exercise tests on different days. During a 20-min inactive recovery period, they breathed freely or against a fixed inspiratory resistance of 15 cm H2O. During recovery, pulmonary gas exchange was continuously monitored, and serial samples of arterialized venous blood were obtained for [Lac(-)]B, pH, PCO2, and HCO3(-). RESULTS: Subjects presented similar ventilatory and gas-exchange responses at peak exercise during both experimental conditions. [Lac(-)]B during recovery was reduced with inspiratory resistance (7.7 +/- 1 vs 10.4 +/- 1, 7.8 +/- 2 vs 10.3 +/- 2, and 7.3 +/- 1 vs 9.7 +/- 2 mM at 5, 7, and 9 min of recovery, respectively; P < 0.05), but no differences were found for blood acid-base status. Inspiratory resistance was associated with increased metabolic demand (V O2 and V CO2) but improved ventilatory efficiency, with lower V E/[V CO2] and increased alveolar ventilation. CONCLUSION: These data are consistent with the notion that inspiratory muscles may be net consumers of lactate during recovery from intense exercise.     

Ventilatory threshold and maximal oxygen uptake during cycling and running in triathletes

VO2max and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained male triathletes. Tvent was indicated as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Triathletes achieved a significantly higher VO2max for TR (75.4 +/- 7.3 ml.kg-1.min-1) than for CE (70.3 +/- 6.0 ml.kg-1.min-1). Mean CE VO2max was 93.2% of the TR value. Average VO2max values for CE and TR compared favorably with values reported for elite single-sport athletes and were greater than those previously reported for other male triathletes. CE Tvent occurred at 3.37 +/- 0.32 l.min-1 or 66.8 +/- 3.7% of CE VO2max, while TR Tvent was detected at 3.87 +/- 0.33 l.min-1 or 71.9 +/- 6.6% of TR VO2max. The VO2 (l.min-1) at which Tvent occurred for TR was significantly higher than for CE (P less than 0.001). Although the VO2 values at TR Tvent expressed as a percentage of VO2max were consistently higher than for CE, the difference between the means did not reach statistical significance (P greater than 0.05). The average Tvent for CE (as %VO2max) was nearly identical to Tvent values reported in the literature for competitive male cyclists, whereas TR Tvent was lower than recently reported values for elite distance runners and marathoners. We speculate that triathlon training results in general (cross-training) adaptations which enhance maximal oxygen uptake values, whereas anaerobic threshold adaptations occur primarily in the specific muscle groups utilized in training.     

Ventilatory threshold and maximal oxygen uptake during cycling and running in female triathletes

Maximal oxygen uptake (VO2max) and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained female triathletes. Tvent was defined as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Female triathletes achieved a significantly higher mean (+/- SE) relative VO2max for running (63.6 +/- 1.2 ml.kg-1.min-1) than for cycling (59.9 +/- 1.3 ml.kg-1.min-1). When oxygen uptake measured at the ventilatory threshold was expressed as a percent of VO2max, the mean value obtained for TR (74.0 +/- 2.0% of VO2max) was significantly greater than the value obtained for CE (62.7 +/- 2.1% of VO2max). This occurred even though the total training time and intensity were similar for the two modes of exercise. Female triathletes had average running and cycling VO2max values that compared favorably with maximal oxygen uptake values previously reported for elite female runners and cyclists, respectively. However, mean running and cycling Tvent values (VO2 Tvent as%VO2max) were lower than recently reported values for single-sport athletes. The physiological variability between the triathletes studied and single-sport athletes may be attributed in part to differences in training distance or intensity, and/or to variations in the number of years of intense training in a specific mode of exercise. It was concluded that these triathletes were well-trained in both running and cycling, but not to the same extent as female athletes who only train and compete in running or cycling.     

Effects of recovery type after a judo combat on blood lactate removal and on performance in an intermittent anaerobic task

AIM: The objective of this study was to verify the effects of active (AR) and passive recovery (PR) after a judo match on blood lactate removal and on performance in an anaerobic intermittent task (4 bouts of upper body Wingate tests with 3-min interval between bouts; 4WT). METHODS: The sample was constituted by 17 male judo players of different competitive levels: A) National (Brazil) and International medallists (n. 5). B) State (S?o Paulo) medallists (n. 7). C) City (S?o Paulo) medallists (n. 5). The subjects were submitted to: 1) a treadmill test for determination of V.O2peak and velocity at anaerobic threshold (VAT); 2) body composition; 3) a 5-min judo combat, 15-min of AR or PR followed by 4WT. RESULTS: The groups did not differ with respect to: body weight, V.O2peak, VAT, body fat percentage, blood lactate after combats. No difference was observed in performance between AR and PR, despite a lower blood lactate after combat (10 and 15 min) during AR compared to PR. Groups A and B performed better in the high-intensity intermittent exercise compared to athletes with lower competitive level (C). CONCLUSION: The ability to maintain power output during intermittent anaerobic exercises can discriminate properly judo players of different levels. Lactate removal was improved with AR when compared to PR but AR did not improve performance in a subsequent intermittent anaerobic exercise.     

A comparative evaluation of the individual anaerobic threshold and the critical power.

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate where blood lactate (La) concentrations are maintained at a steady-state during prolonged exercise. The asymptote of the hyperbolic relationship between power output and time to fatigue has been defined as the critical power (CP), which, in theory, represents the highest metabolic rate where a steady-state response can be achieved during prolonged exercise. Since IAT and CP may define the same power output, the purpose of this study was to compare the gas exchange, blood La, and acid-base responses during exercise at the metabolic rates defined as IAT and CP. Fourteen males performed a maximal incremental cycle exercise test that was followed by a light active recovery period to determine IAT. Subsequently, subjects exercised to fatigue at five power outputs (calculated to elicit from 90% to 110% VO2max) to determine CP. IAT occurred at a significantly lower power output and VO2 (235 +/- 44 W and 2.97 +/- 0.47 l.min-1, respectively) compared with CP (265 +/- 39 W and 3.35 +/- 0.41 l.min-1, respectively). During 30 min of exercise at IAT, blood La levels increased during the initial 10 min to 3.9 +/- 1.9 mmol.l-1 but did not change during the final 15 min. Blood pH decreased to 7.32 +/- 0.04 at 5 min and did not change thereafter, while PCO2 fell from 41.5 +/- 3.2 mm Hg at 5 min to 36.2 +/- 3.6 mm Hg at 30 min. Only one subject completed 30 min of exercise at CP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of specific warm-up at various intensities on energy metabolism during subsequent exercise

BACKGROUND: To investigate the effects of specific warm-up at various intensities on energy metabolism during subsequent intense exercise. METHODS: Experimental design: specific warm-up was consisted of 3 sets of wrist flexions for 5 min, with each set followed by a 3-min rest. The intensity of specific warm-up was set at 20%, 30% or 40% of maximal voluntary contraction (MVC). The subjects then performed a set of wrist flexions at 60% MVC for 4 min as the criterion exercise. For the control experiment, criterion exercise was done without specific warm-up. Participants: Five healthy volunteers. Measurements: using phosphorus-31 magnetic resonance spectroscopy, spectra were obtained from the wrist flexor muscles to determine the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular pH. RESULTS: The Pi/PCr during the criterion exercise after specific warm-up at any intensity was not significantly different from that without specific warm-up. The intracellular pH during the criterion exercise after specific warm-up at 30% or 40% MVC was significantly higher than that without specific warm-up. CONCLUSIONS: These results indicate that mild warm-up exercise could inhibit the development of intracellular acidosis during subsequent intense exercise.     

Blood lactate increase during the force velocity exercise test

Venous blood lactate concentration was measured during the force velocity exercise test in order to determine whether this test is strictly alactic or whether it draws upon lactic anaerobic metabolism. Nine trained male subjects, aged from 23 to 29 years, participated in this study. Two blood samples were drawn at rest, and then for each work load (1 kg to 10 kg): at the end of each sprint (S1) and at the 5th minute of recovery (S2). From the first braking force, venous blood lactate concentration increased very significantly during the force velocity test (p less than 0.001) and, once the peak of power has been obtained, the venous blood lactate concentration remained steady. The lactate increase for each load (delta[LA]) decreased significantly (p less than 0.01). From the beginning of the exercise to the peak of power, a significant positive correlation between the increase of power and the increase of blood lactate concentration measured at S2 existed (r = 0.71, p less than 0.001), whereas there was a negative correlation between the decrease of delta[LA] and the increase of power (r = -0.45, p less than 0.01). In conclusion, the repetition of sprints during the force velocity test induced a recruitment of lactic anaerobic metabolism. Maximal power must be considered as an alactic and lactic anaerobic power. The consequences of lactate accumulation in muscle may be a limitation of the maximal anaerobic power.