Comparison of incremental and steady state tests of endurance training

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

Blood lactate vs. exhaustive exercise to evaluate aerobic fitness

This study compared the predictive power of a lactate-related index determined during submaximal cycle exercise to that of an exhaustive cycle ergometer test for evaluating the endurance exercise capacity of soldiers. The subjects (n = 48 males) performed a continuous exercise test to voluntary exhaustion on the cycle ergometer. Power output (PO) increased by 50 W steps each fourth min, with determinations of heart rate (HR), RPE and blood lactate concentrations (HLa) just prior to each PO increase. The PO at a 4 mmol L(-1) HLa concentration (WOBLA) was interpolated; based on the time to exhaustion the maximal PO that could be maintained for 6 min (Wmax6) was calculated from previously documented formulae. Subjects were timed during a 3000 m cross-country run. Both the cycle test and the run were performed again 3 months later, as was an additional 3000 m run with full military equipment weighing about 21 kg. All 3000 m times were significantly correlated (p less than 0.05) with both Wmax6 and WOBLA; similar predictive power was demonstrated for both Wmax6 and WOBLA, suggesting that accuracy in evaluation would not be sacrificed by substituting the submaximal for the exhaustive exercise test. HR and RPE-related indices showed markedly lower predictive power. The results extend the previously documented relationship between HLa during treadmill ergometry and running performance to include the use of cycle ergometry for the evaluation of running performance. The results also proved applicable to running performance while load carrying.     

Early adaptations in blood substrates, metabolites, and hormones to prolonged exercise training in man.

This study was designed to investigate the effect of short-term, submaximal training on changes in blood substrates, metabolites, and hormonal concentrations during prolonged exercise at the same power output. Cycle training was performed daily by eight male subjects (VO2max = 53.0 +/- 2.0 mL.kg-1.min-1, mean +/- SE) for 10-12 days with each exercise session lasting for 2 h at an average intensity of 59% of VO2max. This training protocol resulted in reductions (p less than 0.05) in blood lactate concentration (mM) at 15 min (2.96 +/- 0.46 vs. 1.73 +/- 0.23), 30 min (2.92 +/- 0.46 vs. 1.70 +/- 0.22), 60 min (2.96 +/- 0.53 vs. 1.72 +/- 0.29), and 90 min (2.58 +/- 1.3 vs. 1.62 +/- 0.23) of exercise. The reduction in blood lactate was also accompanied by lower (p less than 0.05) concentrations of both ammonia and uric acid. Similarly, following training lower concentrations (p less than 0.05) were observed for blood beta-hydroxybutyrate (60 and 90 min) and serum free fatty acids (90 min). Blood glucose (15 and 30 min) and blood glycerol (30 and 60 min) were higher (p less than 0.05) following training, whereas blood alanine and pyruvate were unaffected. For the hormones insulin, glucagon, epinephrine, and norepinephrine, only epinephrine and norepinephrine were altered with training. For both of the catecholamines, the exercise-induced increase was blunted (p less than 0.05) at both 60 and 90 min. As indicated by the changes in blood lactate, ammonia, and uric acid, a depression in glycolysis and IMP formation is suggested as an early adaptive response to prolonged submaximal exercise training.     

Effects of delayed onset muscle soreness on selected physiological responses to submaximal running

This study examined the effects of delayed-onset muscle soreness (DOMS) on selected physiological responses to submaximal exercise. Seven male and four female subjects (Ss) aged 21-37 years completed two submaximal running sessions at an individualized pace corresponding to a blood lactate concentration (bLa) of approximately 2.5 mmol x L(-1). Following the first session (T1), Ss performed a series of lower extremity resistance exercises designed to induce DOMS. Subjects were then retested (T2) 24-30 hours later, during which time all Ss experienced DOMS. Oxygen uptake, heart rate (HR), respiratory exchange ratio, rating of perceived exertion (RPE), and bLa were measured every 6 minutes. Significant trial effects (p < 0.05) were observed for HR and RPE. HR was significantly higher during T1 at minutes 6 and 12 (p < 0.05), and RPE values were significantly higher at T2 during all recording periods (p < 0.05). Results from this study suggest that DOMS does not affect submaximal oxygen uptake. However, DOMS does appear to affect one's perception of effort.     

The effects of one- and two-legged exercise on the lactate and ventilatory threshold

The purpose of this investigation was to compare differences between one- and two-legged exercise on the lactate (LT) and ventilation (VT) threshold. On four separate occasions, eight male volunteer subjects (1-leg VO2max = 3.36 l X min-1; 2-leg VO2max = 4.27 l X min-1) performed 1- and 2-legged submaximal and maximal exercise. Submaximal threshold tests for 1- and 2-legs, began with a warm-up at 50 W and then increased every 3 minutes by 16 W and 50 W, respectively. Similar increments occurred every minute for the maximal tests. Venous blood samples were collected during the last 30 s of each work load, whereas noninvasive gas measures were calculated every 30 s. No differences in VO2 (l X min-1) were found between 1- and 2-legs at LT or VT, but significant differences (p less than 0.05) were recorded at a given power output. Lactate concentration ([LA]) was different (p less than 0.05) between 1- and 2-legs (2.52 vs. 1.97 mmol X l-1) at LT. This suggests it is VO2 rather than muscle mass which affects LT and VT. VO2max for 1-leg exercise was 79% of the 2-leg value. This implies the central circulation rather than the peripheral muscle is limiting to VO2max.     

Day-to-day changes in oxygen uptake kinetics at the onset of exercise during strenuous endurance training.

The aim of this study was to assess the effect of strenuous endurance training on day-to-day changes in oxygen uptake (VO2) on-kinetics (time constant) at the onset of exercise. Four healthy men participated in strenuous training for 30 min.day-1, 6 days.week-1 for 3 weeks. The VO2 was measured breath-by-breath every day except Sunday at exercise intensities corresponding to the lactate threshold (LT) and the onset of blood lactate accumulation (OBLA) which were obtained before training. Furthermore, an incremental exercise test was performed to determine LT, OBLA and maximal oxygen uptake (VO2max) before and after the training period and every weekend. The 30-min heavy endurance training was performed on a cycle ergometer 5 days.week-1 for 3 weeks. Another six men served as the control group. After training, significant reductions of the VO2 time constant for exercise at the pretraining LT exercise intensity (P less than 0.05) and at OBLA exercise intensity (P less than 0.01) were observed, whereas the VO2 time constants in the control group did not change significantly. A high correlation between the decrease in the VO2 time constant and training day was observed in exercise at the pretraining LT exercise intensity (r = -0.76; P less than 0.001) as well as in the OBLA exercise intensity (r = -0.91; P less than 0.001). A significant reduction in the blood lactate concentration during submaximal exercise and in the heart rate on-kinetics was observed in the training group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of detraining on responses to submaximal exercise

Seven endurance-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Heart rate, ventilation, respiratory exchange ratio, and blood lactate concentration during submaximal exercise of the same absolute intensity increased (P less than 0.05) progressively during the first 56 days of detraining, after which a stabilization occurred. These changes paralleled a 40% decline (P less than 0.001) in mitochondrial enzyme activity levels and a 21% increase in total lactate dehydrogenase (LDH) activity (P less than 0.05) in trained skeletal muscle. After 84 days of detraining, the experimental subjects' muscle mitochondrial enzyme levels were still 50% above, and LDH activity was 22% below, sedentary control levels. The blood lactate threshold of the detrained subjects occurred at higher absolute and relative (i.e., 75 +/- 2% vs. 62 +/- 3% of maximal O2 uptake) exercise intensities in the subjects after 84 days of detraining than in untrained controls (P less than 0.05). Thus it appears that a portion of the adaptation to prolonged and intense endurance training that is responsible for the higher lactate threshold in the trained state persists for a long time (greater than 85 days) after training is stopped.     

Effects of training on lactate production and removal during progressive exercise in humans.

To determine whether the reduced blood lactate concentrations [La] during submaximal exercise in humans after endurance training result from a decreased rate of lactate appearance (Ra) or an increased rate of lactate metabolic clearance (MCR), interrelationships among blood [La], lactate Ra, and lactate MCR were investigated in eight untrained men during progressive exercise before and after a 9-wk endurance training program. Radioisotope dilution measurements of L-[U-14C]lactate revealed that the slower rise in blood [La] with increasing O2 uptake (VO2) after training was due to a reduced lactate Ra at the lower work rates [VO2 less than 2.27 l/min, less than 60% maximum VO2 (VO2max); P less than 0.01]. At power outputs closer to maximum, peak lactate Ra values before (215 +/- 28 mumol.min-1.kg-1) and after training (244 +/- 12 mumol.min-1.kg-1) became similar. In contrast, submaximal (less than 75% VO2max) and peak lactate MCR values were higher after than before training (40 +/- 3 vs. 31 +/- 4 ml.min-1.kg-1, P less than 0.05). Thus the lower blood [La] values during exercise after training in this study were caused by a diminished lactate Ra at low absolute and relative work rates and an elevated MCR at higher absolute and all relative work rates during exercise.     

The effects of exercise-induced muscle damage on cycling time-trial performance

Previous research has advocated that plyometric training improves endurance performance. However, a consequence of such a training is the immediate and prolonged appearance of exercise-induced muscle damage (EIMD). This study examined whether a single bout of plyometric exercise, designed to elicit muscle damage, affected cycling endurance performance. Seventeen participants were randomly assigned to either a muscle damage (n = 7 men, 1 woman) or nonmuscle damage (n = 8 men, 1 woman) group. Before and at 48 hours, participants were measured for perceived muscle soreness, peak isokinetic strength, and physiological, metabolic, and perceptual responses during 5-minute submaximal cycling at ventilatory threshold (VT) and a 15-minute time trial. Perceived muscle soreness and isokinetic strength (p < 0.05) were significantly altered in the muscle damage group after EIMD. No changes in heart rate or blood lactate were evident during submaximal exercise (p > 0.05). However, VO2, V(E), and rating of perceived exertion (RPE) values were increased at VT in the muscle damage group at 48 hours after EIMD (p < 0.05). During the time trial, mean power output, distance covered, and VO2 were lower in the muscle damage group at 48 hours after EIMD (p < 0.05). However, there was no change in RPE (p > 0.05), suggesting effort perception was unchanged during time-trial performance after EIMD. In conclusion, individuals using concurrent plyometric and endurance training programs to improve endurance performance should be aware of the acute impact of muscle-damaging exercise on subsequent cycling performance.     

Influence of moderate cold exposure on blood lactate during incremental exercise.

This study examined the effect of exposure of the whole body to moderate cold on blood lactate produced during incremental exercise. Nine subjects were tested in a climatic chamber, the room temperature being controlled either at 30 degrees C or at 10 degrees C. The protocol consisted of exercise increasing in intensity in 35 W increments every 3 min until exhaustion. Oxygen consumption (VO2) was measured during the last minute of each exercise intensity. Blood samples were collected at rest and at exhaustion for the measurement of blood glucose, free fatty acid (FFA), noradrenaline (NA) and adrenaline (A) concentrations and, during the last 15 s of each exercise intensity, for the determination of blood lactate concentration [la-]b. The VO2 was identical under both environments. At 10 degrees C, as compared to 30 degrees C, the lactate anaerobic threshold (Than,la-) occurred at an exercise intensity 15 W higher and [la-]b was lower for submaximal intensities above the Than,la-. Regardless of ambient temperature, glycaemia, A and NA concentrations were higher at exhaustion while FFA was unchanged. At exhaustion the NA concentration was greater at 10 degrees C [15.60 (SEM 3.15) nmol.l-1] than at 30 degrees C [8.64 (SEM 2.37) nmol.l-1]. We concluded that exposure to moderate cold influences the blood lactate produced during incremental exercise. These results suggested that vasoconstriction was partly responsible for the lower [la-]b observed for submaximal high intensities during severe cold exposure.     

Improvements in metabolic and neuromuscular fitness after 12-week bodypump® training

Greco, CC, Oliveira, AS, Pereira, MP, Figueira, TR, Ruas, VD, Gon?alves, M, and Denadai, BS. Improvements in metabolic and neuromuscular fitness after 12-week Bodypump? training. J Strength Cond Res 25(12): 3422-3431, 2011-The purpose of this study was to evaluate the effects of a 12-week group fitness training program (Bodypump?) on anthropometry, muscle strength, and aerobic fitness. Nineteen women (21.4 ± 2.0 years old) were randomly assigned to a training group (n = 9) and to a control group (n = 10). We show that this training program improved the 1 repetition maximum squats by 33.1% (p < 0.001) and the maximal isometric voluntary contraction (MVC) by 13.6% (p < 0.05). Additionally, decreases in knee extensor electromyographic activity during the MVC (30%, p < 0.01) and during the squats (15%, p < 0.05) and lunges of a simulated Bodypump? session were observed after the training. Concomitantly, blood lactate and heart rate after squats of a simulated Bodypump? session were decreased by 33 and 7% (p < 0.05), respectively. Body mass, body fat, and the running velocity at the onset of blood lactate accumulation did not change significantly in response to this training program. We conclude that Bodypump? training improves muscular strength and decreases metabolic stress during lower limb exercises. However, no significant improvements in running aerobic fitness nor in body mass and body fat were observed. Practitioners of Bodypump? training may benefit from the increased muscular strength and the decreased muscular fatigability during exercise tasks whose motor patterns are related to those involved in this training program. However, these functional gains do not seem to be transferable into running aerobic fitness.     

Effect of high-intensity intermittent training on lactate and H+ release from human skeletal muscle

The study investigated the effect of training on lactate and H+ release from human skeletal muscle during one-legged knee-extensor exercise. Six subjects were tested after 7-8 wk of training (fifteen 1-min bouts at approximately 150% of thigh maximal O2 uptake per day). Blood samples, blood flow, and muscle biopsies were obtained during and after a 30-W exercise bout and an incremental test to exhaustion of both trained (T) and untrained (UT) legs. Blood flow was 16% higher in the T than in the UT leg. In the 30-W test, venous lactate and lactate release were lower in the T compared with the UT leg. In the incremental test, time to fatigue was 10.6 +/- 0.7 and 8.2 +/- 0.7 min, respectively, in the T and UT legs (P < 0.05). At exhaustion, venous blood lactate was 10.7 +/- 0.4 and 8.0 +/- 0.9 mmol/l in T and UT legs (P < 0.05), respectively, and lactate release was 19.4 +/- 3.6 and 10.6 +/- 2.0 mmol/min (P < 0.05). H+ release at exhaustion was higher in the T than in the UT leg. Muscle lactate content was 59.0 +/- 15.1 and 96.5 +/- 14.5 mmol/kg dry wt in the T and UT legs, and muscle pH was 6.82 +/- 0.05 and 6.69 +/- 0.04 in the T and UT legs (P = 0.06). The membrane contents of the monocarboxylate transporters MCT1 and MCT4 and the Na+/H+ exchanger were 115 +/- 5 (P < 0.05), 111 +/- 11, and 116 +/- 6% (P < 0.05), respectively, in the T compared with the UT leg. The reason for the training-induced increase in peak lactate and H+ release during exercise is a combination of an increased density of the lactate and H+ transporting systems, an improved blood flow and blood flow distribution, and an increased systemic lactate and H+ clearance.     

Effects of training on glucose metabolism of gluconeogenesis-inhibited short-term-fasted rats

To evaluate the effects of endurance training on gluconeogenesis and blood glucose homeostasis, trained as well as untrained short-term-fasted rats were injected with mercaptopicolinic acid (MPA), a gluconeogenic inhibitor, or the injection vehicle. Glucose kinetics were assessed by primed-continuous venous infusion of [U-14C]- and [6-3H]glucose at rest and during submaximal exercise at 13.4 m/min on level grade. Arterial blood was sampled for the determination of blood glucose and lactate concentrations and specific activities. In resting untrained sham-injected rats, blood glucose and lactate were 7.6 +/- 0.2 and 1.3 +/- 0.1 mM, respectively; glucose rate of appearance (Ra) was 71.1 +/- 12.1 mumol.kg-1.min-1. MPA treatment lowered blood glucose, raised lactate, and decreased glucose Ra. Trained animals had significantly higher glucose Ra at rest and during exercise. At rest, trained MPA-treated rats had lower blood glucose, higher blood lactate, and similar glucose Ra and disappearance rates (Rd) than trained sham-injected animals. Exercising sham-injected untrained animals had increased blood glucose and glucose Ra compared with rest. Exercising trained sham-injected rats had increased blood glucose and glucose Ra and Rd but no change in blood lactate compared with untrained sham-injected animals. In the trained animals during exercise, MPA treatment increased blood lactate and decreased blood glucose and glucose Ra and Rd. There was no measurable glucose recycling in trained or untrained MPA-treated animals either at rest or during submaximal exercise. There was no difference in running time to exhaustion between trained and untrained MPA-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of high intensity interval training on 2,3-diphosphoglycerate at rest and after maximal exercise

The purpose of this study was to examine the effect of intense interval training on erythrocyte 2,3-diphosphoglycerate (2,3-DPG) levels at rest and after maximal exercise. Eight normal men, mean +/- SE = 24.2 +/- 4.3 years, trained 4 days X week-1 for a period of 8 weeks. Each training session consisted of eight maximal 30-s rides on a cycle ergometer, with 4 min active rest between rides . Prior to and after training the subjects performed a maximal 45-s ride on an isokinetic cycle ergometer at 90 rev X min-1 and a graded leg exercise test ( GLET ) to exhaustion on a cycle ergometer. Blood samples were obtained from an antecubital vein before, during and after the GLET only. Training elicited significant increases in the amount of work done during the 45-s ride (P less than 0.05), and also in maximal oxygen uptake (VO2 max: Pre = 4.01 +/- 0.13; Post = 4.29 +/- 0.07 1 X min-1; P less than 0.05) during exercise and total recovery VO2 (Pre = 19.14 +/- 0.09; Post = 21.45 +/- 0.10 1 X 30 min-1; P less than 0.05) after the GLET . After training blood lactate was higher, base excess lower and pH lower during and following the GLET (P less than 0.05 for all variables).(ABSTRACT TRUNCATED AT 250 WORDS)     

Endurance training in older men and women II. Blood lactate response to submaximal exercise

Seven men and four women (age 63 +/- 2 yr, mean +/- SD, range 61-67 yr) participated in a 12-mo endurance training program to determine the effects of low-intensity (LI) and high-intensity (HI) training on the blood lactate response to submaximal exercise in older individuals. Maximal oxygen uptake (VO2max), blood lactate, O2 uptake (VO2), heart rate (HR), ventilation (VE), and respiratory exchange ratio (R) during three submaximal exercise bouts (65-90% VO2max) were determined before training, after 6 mo of LI training, and after an additional 6 mo of HI training. VO2max (ml X kg-1 X min-1) was increased 12% after LI training (P less than 0.05), while HI training induced a further increase of 18% (P less than 0.01). Lactate, HR, VE, and R were significantly lower (P less than 0.05) at the same absolute work rates after LI training, while HI training induced further but smaller reductions in these parameters (P greater than 0.05). In general, at the same relative work rates (ie., % of VO2max) after training, lactate was lower or unchanged, HR and R were unchanged, and VO2 and VE were higher. These findings indicate that LI training in older individuals results in adaptations in the response to submaximal exercise that are similar to those observed in younger populations and that additional higher intensity training results in further but less-marked changes.     

Specificity of physiological adaptation to endurance training in distance runners and competitive walkers

The present study was designed to evaluate the specificity of physiological adaptation to extra endurance training in five female competitive walkers and six female distance runners. The mean velocity (v) during training, corresponding to 4 mM blood lactate [onset of blood lactate accumulation (OBLA)] during treadmill incremental exercise (training v was 2.86 m.s-1, SD 0.21 in walkers and 4.02 m.s-1, SD 0.11 in runners) was added to their normal training programme and was performed for 20 min, 6 days a week for 8 weeks, and was called extra training. An additional six female distance runners performed only their normal training programme every day for about 120 min at an exercise intensity equivalent to their lactate threshold (LT) (i.e. a running v of about 3.33 m.s-1). After the extra training, there were statistically significant increases in blood lactate variables (i.e. oxygen uptake (VO2) at LT, v at LT, VO2 at OBLA, v at OBLA; P less than 0.05), and running v for 3,000 m (P less than 0.01) in the running training group. In the walking training group, there were significant increases in blood lactate variables (i.e., v at LT, v at OBLA; P less than 0.05), and walking economy. In contrast, there were no significant changes in lactate variables, running v and economy in the group of runners which carried out only the normal training programme. It is suggested that the changes in blood lactate variables such as LT and OBLA played a role in improving v of both the distance runners and the competitive walkers.(ABSTRACT TRUNCATED AT 250 WORDS)     

A physiological appraisal of aerobic riding in women

The aim of this study was to compare selected acute cardiorespiratory and metabolic effects of exercise on a Fitness Flyer (FF) aerobic rider to those of treadmill (TM) running. Fourteen women, aged 23-35 years, performed incremental exercise tests to exhaustion on the TM and FF. Ratings of perceived exertion (RPE), heart rate (HR), minute ventilation (VE), VO2, and ventilatory equivalent (VEq) were compared in each subject during each phase of the exercise protocols, and blood lactate concentrations were measured before and 2-3 minutes after the exercise tests on the 2 modalities. Peak VO2 was higher (p < 0.05) on the TM than on the FF. Mean submaximal HR and VEq at a given VO2 was, however, higher on the FF than on the TM (p < 0.05). Maximum mean energy expenditure on the FF corresponded with mean energy expenditure on the TM at 8 km.h(-1) at an 18% gradient. Posttest blood lactate concentrations and RPE were higher on the FF than on the TM (p < 0.05). The results indicate that although exercising on an FF elicits less maximal cardiorespiratory response than does TM running, the FF may be better suited to developing local muscle endurance in the thigh muscles.     

Effects of training on the exercise-induced changes in serum amino acids and hormones

The purpose of this study was to examine power-type athletes to determine changes in amino acid and hormone concentrations in circulating blood following 2 different high-intensity exercise sessions before and after the 5-week training period. Eleven competitive male sprinters and jumpers performed 2 different running exercise sessions: a short run session (SRS) of 3 x 4 x 60 m (intensity of 91-95%) with recoveries of 120 and 360 seconds, and a long run session (LRS) with 20-second intervals (intensity of 56-100%) with recoveries of 100 seconds to exhaustion. The concentrations of serum amino acids, hormones, and lactate were determined from the blood samples drawn after an overnight fast and 10 minutes before and after both SRS and LRS. The average blood lactate concentrations were 12.7 +/- 1.6 mmol;pdL(-1) and 16.6 +/- 1.4 mmol;pdL(-1) (p < 0.01) following SRS and LRS, respectively. The average total running time was longer (p < 0.001) following LRS (164 +/- 20 seconds) than following SRS (91 +/- 8 seconds). The fasting levels of all amino acids decreased (p = 0.024; 19.4%) after the 5-week period, whereas an increase (p = 0.007; 24.5%) was observed in the fasting concentration of testosterone (TE). The exercise sessions induced no changes in the total sum of all amino acids, but significant increases or decreases were observed in single amino acids. When the range of the relative concentration changes before and after the training period was compared, significant decreases were found in valine (p = 0.048), asparagine (p = 0.029), and taurine (p = 0.030) following SRS. There were significant increases in the absolute hormonal concentration changes following LRS with TE (p = 0.002; 30.4%), cortisol (COR; p = 0.006; 12.0%), and in the TE/COR ratio (p = 0.047; 21.0%) but not in the concentration of growth hormone (GH). The results of the study indicate that the speed and strength training period strongly decreases the fasting concentrations of amino acids in the power-trained athletes in a good anabolic state with the daily protein intake of 1.26 g;pdkg(-1) body weight. At the same time the intensive lactic exercise session induces strong decreases, especially in valine, asparagine, and taurine.     

Effect of endurance training on oxygen uptake kinetics during treadmill running.

The purpose of this study was to examine the effect of endurance training on oxygen uptake (VO(2)) kinetics during moderate [below the lactate threshold (LT)] and heavy (above LT) treadmill running. Twenty-three healthy physical education students undertook 6 wk of endurance training that involved continuous and interval running training 3-5 days per week for 20-30 min per session. Before and after the training program, the subjects performed an incremental treadmill test to exhaustion for determination of the LT and the VO(2 max) and a series of 6-min square-wave transitions from rest to running speeds calculated to require 80% of the LT and 50% of the difference between LT and maximal VO(2). The training program caused small (3-4%) but significant increases in LT and maximal VO(2) (P<0.05). The VO(2) kinetics for moderate exercise were not significantly affected by training. For heavy exercise, the time constant and amplitude of the fast component were not significantly affected by training, but the amplitude of the VO(2) slow component was significantly reduced from 321+/-32 to 217+/-23 ml/min (P<0.05). The reduction in the slow component was not significantly correlated to the reduction in blood lactate concentration (r = 0. 39). Although the reduction in the slow component was significantly related to the reduction in minute ventilation (r = 0.46; P<0.05), it was calculated that only 9-14% of the slow component could be attributed to the change in minute ventilation. We conclude that the VO(2) slow component during treadmill running can be attenuated with a short-term program of endurance running training.     

Physiological and performance test correlates of prolonged, high-intensity, intermittent running performance in moderately trained women team sport athletes

A large number of team sports require athletes to repeatedly produce maximal or near maximal sprint efforts of short duration interspersed with longer recovery periods of submaximal intensity. This type of team sport activity can be characterized as prolonged, high-intensity, intermittent running (PHIIR). The primary purpose of the present study was to determine the physiological factors that best relate to a generic PHIIR simulation that reflects team sport running activity. The second purpose of this study was to determine the relationship between common performance tests and the generic PHIIR simulation. Following a familiarization session, 16 moderately trained (VO2max = 40.0 +/- 4.3 ml x kg(-1) x min(-1)) women team sport athletes performed various physiological, anthropometrical, and performance tests and a 30-minute PHIIR sport simulation on a nonmotorized treadmill. The mean heart rate and blood lactate concentration during the PHIIR sport simulation were 164 +/- 6 b x min(-1) and 8.2 +/- 3.3 mmol x L(-1), respectively. Linear regression demonstrated significant relationships between the PHIIR sport simulation distance and running velocity attained at a blood lactate concentration of 4 mmol x L(-1) (LT) (r = 0.77, p < 0.05), 5 x 6-second repeated cycle sprint work (r = 0.56, p < 0.05), 30-second Wingate test (r = 0.61, p < 0.05), peak aerobic running velocity (Vmax) (r = 0.69, p < 0.05), and Yo-Yo Intermittent Recovery Test (Yo-Yo IR1) distance (r = 0.50, p < 0.05), respectively. These results indicate that an increased LT is associated with improved PHIIR performance and that PHIIR performance may be monitored by determining Yo-Yo IR1 performance, 5 x 6-second repeated sprint cycle test work, 30-second Wingate test performance, Vmax, or LT. We suggest that training programs should focus on improving both LT and Vmax for increasing PHIIR performance in moderately trained women. Future studies should examine optimal training methods for improving these capacities in team sport athletes.