Physical working capacity and mile run performance in adolescent boys.

The degree of generality between the endurance characteristics of the one mile run and PWC170 tests was examined with a group of fifteen year old boys who performed both tests once a week for three weeks. A significant improvement in performance of both tests was found between trials 1 and 2, which was sustained between trials 2 and 3. These results suggest that norm scales regarding performance in both tests should be based on the average of at least two trials following a practice trial. The results of the present study also suggest that when average scores are used, rather than single scores, the amount of generality between the endurance characteristics of the one mile run and PWC170 test is high enough to allow physical working capacity to be predicted fairly accurately from performance in the one mile run.     

A comparison of the PWC170 and 20-MST tests of aerobic fitness in adolescent schoolchildren

The aim of this study was to compare the validity of two field tests of aerobic fitness for predicting maximal oxygen uptake (VO2max) in a group of adolescent schoolchildren. Twenty four schoolboys (means age = 15.6 +/- 0.6 yr) and twenty four schoolgirls (means age = 15.4 +/- 0.7 yr) underwent three different tests of aerobic capacity, with one week separating each assessment. The test were: (a) VO2max, using a continuous, progressive treadmill protocol, (b) a physical work capacity test at a heart rate of 170 beats per minute (PWC170), and (c) a 20-metre endurance shuttle run (20-MST), using a modified lapscoring protocol. Heart rates were monitored continuously in all tests. Results (means +/- SD) for boys n = 23) and girls (n = 18) respectively were: VO2max, 53.3 +/- 5.9 and 42.6 +/- 5.8 ml.kg-1.min-1; PWC170, 2.84 +/- 0.47 and 1.86 +/- 0.39 w.kg-1; 20-MST, 81.7 +/- 15.9 and 50.4 +/- 12.5 laps. Linear regression of PWC170 and 20-MST on VO2max scores (n = 41), revealed similarly high powers of prediction for both field tests (PWC170 vs VO2max, r = 0.84; 20-MST vs VO2max, r = 0.87), with an indication that the shuttle run test may be preferable for use with girls. In conclusion, the PWC170 and 20-MST field tests both appear to be valid predictors of VO2max in adolescent schoolchildren. However constraints of time and tester expertise favour the 20-MST for the assessment of aerobic capacity in the field.     

Maximal but not submaximal performance is reduced by constant-speed 10-km run

AIM: Effects of endurance exercise on running economy, mechanics, force generating capacity and their interactions were examined. During the exercise, metabolic, kinetic and kinematic variables were recorded to find out adaptive mechanisms in the course of the fatiguing run. In addition, before and after it maximal force and power production was tested. METHODS: Experimental design: comparative. Setting: University. Participants and intervention: 7 men unaccustomed to endurance training run 10 km at individually chosen constant speed (3.5+/-0.5 m x s(-1)) on an indoor track. Measures: 3-D ground reaction forces, electromyographic (EMG) activities from 7 leg muscles, pulmonary ventilation, gas exchange, heart rate and movement kinematics were measured during the run. Blood lactate and serum creatine kinase activity were determined. Maximal voluntary contraction (MVC) with superimposed double twitch (DT), and passive DT tests in plantarflexor muscles were performed before and after the 10 km run. Changes in 20 m sprint performance were evaluated in before-after comparison. RESULTS: The 10 km run caused significant reductions in maximal running speed (8.2 vs 7.6 m x s(-1), p<0.05), in MVC (1216 vs. 984 N, p<0.05), and in passive DT (271 vs 211 N, p<0.05). During the submaximal run, however, the subjects were able to maintain relatively constant oxygen consumption and running kinematics. Greatest changes in EMG activity and kinetics were seen during the first 2 km. CONCLUSION: After initial adjustment, the runners are able to maintain submaximal running speed with very little changes in running economy, kinetics and kinematics. However, fatigue-induced impairment in the force generating capacity of the contractile component can be revealed by tests measuring maximum performance.     

The oxygen uptake response of sprint- vs. endurance-trained runners to severe intensity running.

We compared the oxygen uptake (VO2) response of sprint- and endurance-trained runners for an exhaustive square wave run lasting approximately 2 minutes. Six sprinters and six middle- and long-distance runners each performed two exhaustive square wave runs lasting approximately 2 min and two exhaustive ramp tests. VO2 was determined breath-by-breath (QP9000; Morgan Medical, Rainham, UK) and averaged across the two repeats of each test; for the square wave test, the averaged VO2 response (excluding the first 15 s) was then modelled using a monoexponential function. Both VO2peak for the ramp test (67.5+/-3.3 vs. 54.5+/-8.5 mlxkg(-1)xmin(-1); P= 0.006) and the asymptotic VO2 for the square wave run (59.6+/-2.7 vs. 50.7+/-4.6 mlxkg(-1)xmin(-1); P= 0.002) were higher for the endurance than for the sprint group. However, as a percentage of VO2peak, this asymptotic VO2 did not differ between the groups (90.1+/-3.2% (endurance) vs. 96.2+/-9.0% (sprint); P= 0.145). Across all 12 subjects, the %VO2peak attained in the square wave run was negatively correlated with VO2peak (Pearson's r= -0.811, P= 0.001). We conclude that VO2max is more important than training history as a determinant of the %VO2max attained in exhaustive square wave running lasting approximately 2 min.     

An evaluation of tests of anaerobic power

The objectives of this study were to examine the relationships between two recently developed laboratory tests of anaerobic power (AnP) and to compare these tests to other measures of AnP. Fifteen male subjects, aged 20-34 years, performed: a 30-s maximal cycle ergometer test (Wingate test), a 60-s isokinetic knee extension test (isokinetic endurance test), a 50-m sprint, a 200-m sprint, and the Margaria stair-climb test. Significant correlations ranging from 0.52-0.76 were found between the Wingate and isokinetic endurance tests for peak and mean values of power and torque, respectively. Indices from both these tests also correlated significantly with the other tests of AnP. The best single index was mean power from the Wingate test, which had correlations of -0.79, -0.82, and 0.74 with the 50-m and 200-m sprint times and the Margaria test, respectively. The data suggest that both the Wingate and isokinetic endurance tests represent valid laboratory tests for evaluating high-intensity, short-term exercise in which the muscle is primarily dependent upon anaerobic processes for energy release.     

20-MST and PWC170 validity in non-Caucasian children in the UK.

The validity was investigated of 20-MST (20 Metre Endurance Shuttle Run Test) and PWC170 (Physical Working Capacity) field tests with laboratory-measured peak oxygen uptake (VO2peak) in a multiracial UK population of 12-year olds: 103 subjects completed the 20-MST and 96 of these completed the PWC170. To assess validity, a laboratory treadmill test was completed by ten boys and ten girls who had performed both field tests. VO2peak was 43.8 ml kg-1 min-1 for boys and 38.5 ml kg-1 min-1 for girls. Pearson product-moment correlation showed 20-MST to be a reliable measure of cardiorespiratory fitness (r = 0.83, boys; r = 0.76, girls, P less than 0.03), while correlations with PWC170 were lower (r = 0.64, boys; r = 0.54, girls) and not significant. The 20-MST was consistent in retest (n = 20) - reliability coefficients r = 0.73, boys; r = 0.88, girls; P less than 0.01. The results suggest 20-MST is a valid, measure of fitness in this population when compared with VO2peak. PWC170 is less valid, possibly due to cultural and social backgrounds. The cycle test was inappropriate in this population, especially for girls unaccustomed to exercise and cycling. The 20-MST test is recommended for large groups of children when facilities are limited. It requires limited skill or habituation and is relatively non-invasive.     

Effect of intermittent hypoxic training on 20 km time trial and 30 s anaerobic performance

This study aimed to verify whether the “live low, train high” approach is beneficial for endurance and/or anaerobic cycling performance. Sixteen well‐trained athletes completed 90 min of endurance training (60–70% of heart rate reserve), followed by two 30‐s all‐out sprints (Wingate test), daily, for 10 consecutive days. Nine subjects [intermittent hypoxic training (IHT) group] trained with an F_IO₂ set to produce arterial oxygen saturations of ～88–82%, while seven subjects (placebo group) trained while breathing a normal gas mixture (F_IO₂=0.21). Four performance tests were conducted at sea level including a familiarization and baseline trial, followed by repeat trials at 2 and 9 days post‐intervention. Relative to the placebo group, the mean power during the 30‐s Wingate test increased by 3.0% (95% confidence limits, CL ± 3.5%) 2 days, and 1.7% (± 3.8%) 9 days post‐IHT. Changes in other performance variables (30 s peak power, 20 km mean power and 20 km oxygen cost) were unclear. During the time trial, the IHT participants' blood lactate concentration, respiratory exchange ratio, and SpO₂, relative to the placebo group, was substantially increased at 2 days post‐intervention. The addition of IHT to the normal training program of well‐trained athletes produced worthwhile gains in 30 s sprint performance possibly through enhanced glycolysis.     

Relationship between measured maximal oxygen uptake and aerobic endurance performance with running repeated sprint ability in young elite soccer players

AIM: The aim of the study was to determine the relationships between maximal oxygen uptake (VO(2max)) in a maximal treadmill run and the aerobic endurance performance in the 20-m multistage shuttle run (MST) test, with the performance indices obtained in the running repeated sprint ability (rRSA) test, in elite youth soccer players. METHODS: Thirty-seven adolescent male outfield players performed on separate days and in random order the treadmill run test and the MST, to obtain their measured VO(2max) and aerobic endurance performance (via the number of completed shuttles in the MST), respectively. Players also completed the rRSA test of 6x20-m all-out sprints, interspersed with 20 s of active recovery. RESULTS: There was a significant moderate correlation between measured VO(2max) (in L . min(-1) and mL . kg(-1) . min(-1)) and MST results (r=0.43 and 0.54, P<0.05, respectively). There was no significant correlation between measured VO(2max) and aerobic endurance performance with any of the performance indices in the rRSA test (all P>0.05). CONCLUSION: The moderate association between the measured VO(2max) and MST suggests that both tests were plausibly measuring different aspects of a player's aerobic fitness. The lack of association between measured VO(2max) and aerobic endurance performance in the MST with performance in the rRSA suggests that aerobic fitness per se is poorly associated with performance in the rRSA in elite youth soccer players.     

A study of the physical working capacity of Gaelic footballers and hurlers.

The possible contribution of endurance fitness to performance in the Gelic games, football and hurling, has been investigated. Two groups of 15 players were compared. The first consisted of members of teams reaching interprovincial finals and the second were similar members of comparable but less successful teams. The measurements taken were: height and weight, skinfold thicknesses on the triceps, biceps, subscapular and suprailiac sites, and the physical working capacity at a heart rate of 170 beats per minute (PWC 170). The more successful players were found to be taller and heavier and to have a higher PWC 170. There was no difference in estimated percentage of fat. The difference in PWC 170 of the two groups remained after correction for the difference in body weight. A group of seven of the players who participated in two or more finals was studied longitudinally. In six of these subjects PWC 170 was higher at the time of these matches than before or after. These findings are discussed and it is suggested that endurance fitness is a factor contributing to performance in football and hurling.     

A multi-stage shuttle run as a predictor of running performance and maximal oxygen uptake in adults.

The aim of this study was to assess the validity of a 20 metre multi-stage shuttle run (20-MST) as both a field test of cardiorespiratory endurance and as a predictor of competitive performance in a 10 kilometre (10 km) race. Nine male subjects (age 35.4 +/- 5.8 years) (mean +/- SD) underwent a laboratory test of maximum oxygen uptake on a treadmill (VO2 max 59.0 +/- 9.9 ml.kg.-1min-1), completed the 20-MST (score 105 +/- 23.7 laps/11.4 +/- 2.7 paliers) and competed in a 10 km race (finishing time 41.8 +/- 7.3 minutes). Analysis using Pearson's Product Moment Coefficient revealed high correlations between these variables (20-MST vs. VO2 max, r = 0.93; 20-MST vs. 10 km, r = -0.93; VO2 max vs. 10 km, r = -0.95). These results confirm that the 20-MST is a valid field test of cardio-respiratory endurance and suggest that it can additionally be used to predict relative running performance over 10 km.     

The validity of a repeated sprint ability test

Many team sports require participants to repeatedly produce maximal or near maximal sprints of short duration (1-7s) with brief recovery periods, over an extended period of time (60-90 min). Therefore, an important fitness component for these sports is what is often termed repeated sprint ability (RSA). A variety of tests have been devised to assess RSA. However, while the reliability of some of these tests has been reported, there has been no published attempt to assess the validity of RSA tests. The purpose of the present paper was to assess the validity of a popular RSA test--the 5 x 6 s cycle test. Ten moderately-trained males (Mean+/-SD age: 23.6+/-3.0 yrs, mass: 71.8+/-7.4 kg, peak VO2: 46.32+/-4.16 ml.kg(-1)min(-1)) participated in the investigation. Following familiarisation, subjects reported to the laboratory at the same time of day, on three occasions, each separated by at least 48 hours. Testing consisted of a 5 x 6 s cycle test (5 x 6 s maximal sprints every 30 s), a graded exercise test (GXT) and a simulated game (3 x 15 min periods separated by five min). The simulated game consisted of a 1-min circuit that was repeated 15 times in each period. The circuit replicated typical movement patterns observed during motion analysis of field hockey games. Each circuit commenced with a 15-m maximum sprint through timing gates. Time to run 5, 10 and 15 m was recorded. Oxygen consumption was measured during both the GXT and the simulated game with a portable gas analysis system (Cosmed K4 b2, Italy). Correlation coefficients between dependent variables were calculated using Pearson's Product Moment (r). There was a significant correlation between power decrement during the 5 x 6 s cycle test and decrement in 15-m time across the three periods (r = 0.76, P<0.05), but not decrement in 10-m time (r = 0.54) or 5-m time (r = 0.42). These results suggest that the 5 x 6 s cycle test is valid for assessing the decrement in 15-m time, but not the decrement in 5 or 10m time. Thus, one measure of RSA (sprint decrement) appears to be specific to the test protocol, rather than a general quality. The most likely explanation is that the energy requirements of the 5 x 6 s cycle test more closely match those required to repeatedly run 15 m (mean time = 2.74 s) than to repeatedly run 10 m (mean time = 1.97 s) or 5 m (mean time = 1.13 s). It is therefore suggested that, while the 5 x 6 s cycle test is often used to assess RSA ability in a wide range of sports, it may need to be modified to reflect the common sprint distances found in specific sports.     

Accuracy of physical working capacity 170 to estimate aerobic fitness in prepubertal diabetic boys and in 2 insulin dose conditions

AIM: Exercise tests evaluate the effects of physical activity, which is one of the four recommendations for diabetes treatment. An adjusted and accurate measure of aerobic capacity in diabetic patients is thus needed. This study compared two estimates of aerobic fitness (maximal oxygen uptake vs physical working activity PWC170, i.e., the workload at a pulse of 170) and the usual versus a reduced insulin dose in preadolescent boys with type 1 diabetes mellitus. METHODS: Sixteen prepubertal type 1 diabetic boys performed a submaximal test, the PWC(170). Gas exchange values and capillary blood glucose levels were monitored and, when possible, the test was extended to exhaustion. In 7 boys, the test was performed twice on separate days. On one day they received their usual insulin dose and on the other, their short-acting insulin was reduced by 1/3; the two tests were held in random order. The 9 other children were tested only once after receiving their usual insulin dose. RESULTS: For the 16 boys who performed the test with the usual insulin dose, PWC(170) (W) and peak oxygen uptake (peak VO(2)) (L.min(-1)) correlated closely (r=0.81, P=0.002). Aerobic fitness did not change with insulin dose, but some hypoglycemic episodes occurred when insulin dose was not reduced. CONCLUSIONS: Since maximal effort does not add more information, routine use of the submaximal peak VO(2)-correlated test, the PWC(170), seems sufficient, possibly in association with a planned insulin dose reduction. This dose change does not interfere with performance, but could reduce the risk of hypoglycemia.     

A comparison of methods of predicting maximum oxygen uptake.

The aim of this study was to compare the results from a Cooper walk run test, a multistage shuttle run test, and a submaximal cycle test with the direct measurement of maximum oxygen uptake on a treadmill. Three predictive tests of maximum oxygen uptake--linear extrapolation of heart rate of VO2 collected from a submaximal cycle ergometer test (predicted L/E), the Cooper 12 min walk, run test, and a multi-stage progressive shuttle run test (MST)--were performed by 22 young healthy males (mean(s.d.) age 22.1 (2.4) years; body mass 72.4(8.9kg)) and the values compared to those obtained by direct measurement on a maximal treadmill test. All of the subjects were regular exercisers. The mean(s.d.) from the various tests in ml.kg-1.min-1 were as follows: treadmill 60.1(8.0), Cooper 60.6(10.3), MST 55.6(8.0), and predictedL/E 52.0(8.4). The Cooper test had a correlation with the treadmill test of 0.92, while the MST and the predictedL/E had correlations of 0.86 and 0.76 respectively. Both the MST and predictedL/E showed systematic underprediction of the treadmill value. On average, the MST was 4.5 ml.kg-1.min-1 (s.e. 0.9) lower than the treadmill VO2max while the predictedL/E was 7.8 ml.kg-1. min-1 (s.e. 1.4) lower than the treadmill VO2max. These findings indicate that, for the population assessed, the Cooper walk run test is the best predictor of VO2max among the three tests.     

Changes in cycling efficiency and performance after endurance exercise

PURPOSE: This study was designed to examine the effects of moderate-intensity endurance exercise on cycling performance, gross efficiency, and 30-s sprint power output. METHODS: Two separate experiments were conducted. After a controlled warm-up, subjects completed as much work as possible in a 5-min performance test (EXP1) or a maximal 30-s sprint test (EXP2). These initial exercise bouts were followed by approximately 60 min of cycling at approximately 60% VO2peak or an equivalent period of rest (control) before repeating the warm-up exercise and either the 5-min performance or 30-s sprint test. Expired gas for calculation of cycling gross efficiency was collected over the last minute of each warm-up period. RESULTS: Average 5-min performance power output was significantly reduced (12 W) after exercise in EXP1, and in EXP2 both peak and mean power output were significantly lower (26 and 35 W, respectively). Gross efficiency decreased significantly with exercise in both EXP1 and EXP2. Moreover, the change in gross efficiency was correlated with the change in 5-min performance (r = 0.91, P < 0.01), but not with the change in mean or peak 30-s sprint power output. CONCLUSIONS: After sustained moderate-intensity cycling significant reductions in 5-min performance, gross efficiency and sprint power output were observed in endurance trained cyclists. The reduction in 5-min performance was related to the exercise induced decrease in gross efficiency.     

Breathing pattern and ventilatory response to CO2 during exercise.

The aim of this study was to determine during moderate exercise whether response to the CO2 rebreathing test was dependent on differences in breathing pattern components among individuals recorded before the test and whether differences in tidal volume response and/or breathing frequency response to CO2 during the test could influence their ventilatory response to CO2. Ten healthy, sedentary male subjects, 20 to 34 years old, participated in the study. Ventilatory response to CO2 was measured by the CO2 rebreathing method (7% CO2, 50% O2). The measurements of breathing pattern components and CO2 rebreathing were made during mild steady state exercise: VCO2 = 20 ml.kg-1.min-1. We measured the following: 1) tidal volume (VTex) and breathing frequency (fex) before CO2 rebreathing and 2) ventilatory response to CO2 (SVEex), tidal volume response to CO2 (SVTex), and breathing frequency response to CO2 (Sfex) during the CO2 rebreathing test. The results showed that SVEex was correlated with VTex (r = 0.89, p less than 0.001), fex (r = -0.79, p less than 0.01), and Sfex (r = 0.83, p less than 0.01). There was no correlation between SVEex and SVTex. A curvilinear relationship existed between SVEex and alveolar ventilation calculated during exercise (r = 0.87, p less than 0.001), but there was no correlation with dead space. Sfex was positively correlated with VTex (r = 0.68, p less than 0.05) and negatively with fex (r = -0.70, p less than 0.05). We concluded that, during moderate exercise, higher tidal volumes measured before CO2 rebreathing were associated with higher response to the CO2 rebreathing test and consequently with higher ventilatory response to CO2.(ABSTRACT TRUNCATED AT 250 WORDS)     

31P-MRS characterization of sprint and endurance trained athletes

Muscle metabolism and force production were studied in sprint trained runners, endurance trained runners and in untrained subjects, using 31P-MRS. 31P-spectra were obtained at a time resolution of 5 s during four maximal isometric contractions of 30-sec duration, interspersed by 60-sec recovery intervals. Resting CrP/ATP ratio averaged 3.3 +/- 0.3, with no difference among the three groups. The sprint trained subjects showed about 20 % larger contraction forces in contraction bouts 1 and 2 (p < 0.05). The groups differed with respect to CrP breakdown (p < 0.05), with sprinters demonstrating about 75 % breakdown in each contraction compared to about 60 % and 40 % for untrained and endurance trained subjects, respectively (p < 0.05). The endurance trained runners showed almost twice as fast CrP recovery (t 1/2 = 12.5 +/- 1.5) compared to sprint trained (t 1/2 = 22.5 +/- 2.53) and untrained subjects (t 1/2 = 26.4 +/- 2.8). From the initial rate of CrP resynthesis the rate of maximal aerobic ATP synthesis was estimated to 0.74 +/- 0.07, 0.73 +/- 0.10 and 0.33 +/- 0.07 mmol ATP x kg -1 wet muscle x sec -1 for sprint trained, endurance trained and untrained subjects, respectively. Only the sprint trained and the untrained subjects displayed a significant drop in pH and only during the first of the four contractions, about 0.2 and 0.1 pH units, respectively, indicating that only under those contractions was the glycolytic proton production larger than the proton consumption by the CK reaction. Also, in the first contraction the energy cost of contraction was higher for the sprinters compared to the two other groups. The simple 31P-MRS protocol used in the present study demonstrates marked differences in force production, aerobic as well as anaerobic muscle metabolism, clearly allowing differentiation between endurance trained, sprint trained and untrained subjects.     

Field test evaluation of aerobic, anaerobic, and wheelchair basketball skill performances

Forty-six male wheelchair basketball players performed a set of field tests to evaluate aerobic capacity (25 m shuttle run), anaerobic capacity (30s sprint), and six specific wheelchair basketball skills. Overall test-retest reliability (n = 20) ranged from r = 0.65 to r = 0.97. To study the validity (criterion related evidence) of the shuttle run test, heart rate (HR) was recorded for 15 subjects, who also performed a continuous, multistage arm cranking exercise until volitional fatigue. Moderate to high correlations were calculated between shuttle run distances covered (1375 243,6 m) and VO2max (2208+/-461.6 mL/min) and POmax (93.8+/-17.97 W), measured during maximal arm cranking (respectively r = 0.64 and r = 0.87). Maximal HR during shuttle run (174.9+/-16.6 B/min) and arm cranking (169+/-14.21 B/min) were correlated (r = 0.78). High correlations between shuttle run test and anaerobic field tests, however, indicate high implication of anaerobic and wheelchair maneuverability performances. The 30 s sprint test was validated (n = 15) against a Wingate Anaerobic Test (WAnT) on a roller ergometer. Comparing distance (field test: 90+/-6.7 m) with mean power output (WAnT: 852.1+/-234.9 W) the correlation was r = 0.93. Principal components factor analysis identified 'wheelchair propulsion dynamics' and 'eye-hand-coordination' as the underlying constructs of the six skill proficiency measurements, accounting for 80.1% of the variance. In conclusion, the newly developed field test battery is a reliable and valid tool for anaerobic capacity and skill proficiency assessment in wheelchair basketball players.     

Reliability of sprint test indices in well-trained cyclists

The study aim was to assess reliability of repeated laboratory sprint tests in well-trained endurance cyclists. Eleven male cyclists (mean +/- standard deviation: 27 +/- 6 yr, 1.79 +/- 0.04 m, 70.1 +/- 3.3 kg) performed a maximal 30-second sprint test on four separate occasions using their own bicycle fitted with an SRM powermeter on a Kingcycle air-braked ergometer. Peak power output (W (peak)), mean power (W (mean)) and an index of fatigue (FI) were calculated. Three minutes post sprint, capillarised blood lactate measurements were taken and analysed. No significant differences (p > 0.05) were found between trials for W (peak), W (mean), FI and blood lactate concentration. Repeatability of W (peak), W (mean), and fatigue index improved across trials 2 and 3 when compared to trials 1 and 2. The highest CV for these variables was recorded between trials 3 and 4. The CV for W (peak) was 4.5 +/- 1.6 %, W (mean) 2.4 +/- 1.2 %, and FI 17.2 +/- 7.1 %. Intraclass reliability coefficients were 0.93 (95 % CI 0.84 - 0.98), 0.94 (95 % CI 0.86 - 0.98) and 0.89 (95 % CI 0.69 - 0.95) respectively. Blood lactate concentration ranged between 5.35 and 14.52 mmol.l(-1), with a mean CV of 12.1 +/- 4.2 %. The CV for trials 2 and 3 revealed the highest CV for blood lactate concentration (15.1 %). The lowest CV for this variable (10.2 %) was recorded between trials 3 and 4. The intraclass reliability coefficient for blood lactate concentration was 0.79 (95 % CI 0.58 - 0.93). The results of this study indicate that there is no improvement in the reliability of sprint test indices when assessing well-trained, experienced cyclists, riding on their own cycle equipment.     

Specificity of aerobic and anaerobic work capacities and powers

Thirty-three untrained subjects of both sexes, 18-31 years of age, performed several tests on cycle ergometers. Maximal aerobic power (MAP) was obtained in a progressive work test. Maximal aerobic capacity (MAC) was measured in a 90-min maximal test and was computed as the total work output during that period. Two all-out cycle ergometer work tests lasting 10 s and 90 s were used to estimate the anaerobic alactic capacity (AAC) and lactic capacity (ALC). Anaerobic alactic power (AAP) was computed as the highest output in 1 s in the AAC test and anaerobic lactic power (ALP) was obtained as the mean output during the last 5 s in an all-out test of 30 s. Correlation coefficients were computed between all measurements of capacity and power expressed per kg of body weight as well as with scores adjusted for sex differences. Common variances (r2 X 100) between measurements of power were either low (MAP-AAP, 40%) or moderate (MAP-ALP, 61%; AAP-ALP, 62%) while common variances between measurements of capacity were sometimes low (MAC-AAC, 49%) or higher (MAC-ALC, 76%; AAC-ALC, 77%). The common variances between tests of power and capacity reached high values when calculated with metabolic criteria of the same class (MAP-MAC, 81%; AAP-AAC, 92%). These results provide quantitative evidence to support the notion of specificity between the aerobic and the anaerobic work performances and support the distinction between capacity and power of the three energy systems.     

Effects of phosphate loading on leg power and high intensity treadmill exercise

Stim-O-Stam is a commercial ergogenic aid purported to improve human performance by reducing recovery time and enhancing endurance. The tablets contain a mixture of sodium acid phosphate and potassium phosphate. In this study, under a double-blind cross-over design, 11 male subjects underwent acute (1.24 g one hour before exercise) and chronic (3.73 g X d-1 for 6 d prior to exercise) consumption of Stim-O-Stam to determine the effects of phosphate loading on: treadmill endurance time; treadmill endurance time after 15 min of recovery from first treadmill run; leg power measured for 1 min on the Cybex device; leg power after 10 min recovery from first power test; and oxygen uptake during the treadmill run. Run times ranged from 172 to 183 s on run 1 and 145 to 152 s for run 2. Leg power averaged 62 W for both tests. Oxygen uptake averaged 52 ml X kg-1 X min-1 under all conditions. Analysis of variance showed that there was no significant effect of acute or chronic ingestion of phosphate tablets beyond that of the placebo treatment on any of the performance tests. These results argue against the claim of ergogenic benefits ascribed to this nutritional supplement.