Predicting maximal aerobic capacity (VO2max) from the critical velocity test in female collegiate rowers

The objective of this study was to examine the relationship between the critical velocity (CV) test and maximal oxygen consumption (VO2max) and develop a regression equation to predict VO2max based on the CV test in female collegiate rowers. Thirty-five female (mean ± SD; age, 19.38 ± 1.3 years; height, 170.27 ± 6.07 cm; body mass, 69.58 ± 0.3 1 kg) collegiate rowers performed 2 incremental VO2max tests to volitional exhaustion on a Concept II Model D rowing ergometer to determine VO2max. After a 72-hour rest period, each rower completed 4 time trials at varying distances for the determination of CV and anaerobic rowing capacity (ARC). A positive correlation was observed between CV and absolute VO2max (r = 0.775, p < 0.001) and ARC and absolute VO2max (r = 0.414, p = 0.040). Based on the significant correlation analysis, a linear regression equation was developed to predict the absolute VO2max from CV and ARC (absolute VO2max = 1.579[CV] + 0.008[ARC] - 3.838; standard error of the estimate [SEE] = 0.192 L·min(-1)). Cross validation analyses were performed using an independent sample of 10 rowers. There was no significant difference between the mean predicted VO2max (3.02 L·min(-1)) and the observed VO2max (3.10 L·min(-1)). The constant error, SEE and validity coefficient (r) were 0.076 L·min(-1), 0.144 L·min(-1), and 0.72, respectively. The total error value was 0.155 L·min(-1). The positive relationship between CV, ARC, and VO2max suggests that the CV test may be a practical alternative to measuring the maximal oxygen uptake in the absence of a metabolic cart. Additional studies are needed to validate the regression equation using a larger sample size and different populations (junior- and senior-level female rowers) and to determine the accuracy of the equation in tracking changes after a training intervention.     

Sustainability of critical power determined by a 3-minute all-out test in elite cyclists

Critical power (CP) is a theoretical workload representative of an athlete's maximal sustainable pace. Recent research has validated a 3-minute all-out test on a cycle ergometer for determining CP; however, few studies have investigated the sustainability of CP using this test. The purpose of this study was to determine the sustainability of CP established during the 3-minute test and the determinants of sustainability. A group of elite cyclists (N = 21) performed a VO2max test, 3-minute all-out test, and a time to exhaustion (TTE) trial at CP on 3 different days separated by at least 24 hours. Expired gases were collected during all trials and analyzed for VO2 and VCO2. Heart rate was measured by telemetry. Multiple regression was used to determine predictors of sustainability with significance predetermined at p < 0.05. VO2max was measured at 58.9 ± 5.6 ml·kg(-1)·min(-1), ventilation breakpoint at 44.9 ± 5.7 ml·kg(-1)·min(-1) (75% VO2max), and maximum heart rate at 179 ± 10 b·min(-1). Peak power (PP) in the 3-minute all-out test was measured at 738 ± 170 W, and CP was determined at 305 ± 32 W or 79% of VO2max. The VO2 at CP was 55.4 ± 6.9 ml·kg(-1)·min(-1), representing 94% of measured VO2max. The mean TTE at CP was 14.79 ± 8.38 minutes. The difference score of PP - CP significantly predicted TTE (r = 0.65, p < 0.05). No other measured variables contributed to this prediction. Based on sustainability, these data suggest that the 3-minute all-out test may overestimate CP in elite cyclists, which could lead to overtraining if CP determined with this test is used to identify training intensities.     

Fit women are not able to use the whole aerobic capacity during aerobic dance

Edvardsen, E, Ingjer, F, and B?, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (VO(2)max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to ≤0.05. The results (mean ± SD) showed a lower VO(2)max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15 b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.     

Validity of Carminatti's test to determine physiological indices of aerobic power and capacity in soccer and futsal players

The aim of this study was to verify the validity of a new progressive distance and fixed time test (Carminatti's test [TCAR]) in estimating the main physiological indices of aerobic fitness in team-sport players. Thirty professional national level team-sport players (n = 12 futsal players and 18 soccer players) volunteered to participate in this study. The subjects performed the TCAR and a laboratory incremental treadmill test (ITT). The TCAR required subjects to complete repeated sets of 5 × 12-second shuttle-running bouts at progressive speed until volitional exhaustion. Each 12-second bout and series were separated by a 6- and 90-second recovery periods, respectively. The initial distance was set at 15 m and was progressively increased by 1 m each set. The ITT commenced at a velocity of 9.0 km·h(-1) and was increased by 1.2 km·h(-1) each 3 minutes until volitional exhaustion. Peak TCAR running velocity resulted not significantly (p > 0.05) different from speed at VO2max (vVO2max) during ITT. Peak TCAR running velocity was significantly correlated (p < 0.01) with vVO2max (r = 0.55) and VO2max (r = 0.51). No significant differences were found (p > 0.05) among the mean values of velocity and heart rate at the anaerobic threshold, estimated in the TCAR test and measured in the ITT. In light of this study results, the TCAR can be considered as a viable field test to estimate aerobic power and capacity in team-sports players. The limited devices and space required by TCAR warrant consideration for those strength and conditioning professionals who deal with team sports.     

A physiological description of critical velocity

Although critical velocity (CV) provides a valid index of aerobic function, the physiological significance of CV is not known. Twelve individuals performed exhaustive runs at 95% to 110% of the velocity at which VO2max was attained in an incremental test. VO2max was elicited in each run. Using the time to exhaustion at each velocity, CV was calculated for each participant. Using the time to achieve VO2max at each velocity, which was shorter at higher velocities, a parameter we have designated as CV' was calculated for each participant. During exercise at or below CV', VO2max cannot be elicited. CV (238+/-24 m x min(-1)) and CV' (239+/-25 m x min(-1)) were equal (t = 0.60, p = 0.56) and correlated (r = 0.97, p < 0.01). These results demonstrate that CV is the threshold intensity above which exercise of sufficient duration will lead to attainment of VO2max.     

Evaluation of the American College of Sports Medicine submaximal treadmill running test for predicting VO2max

The purpose of this study was to assess the validity of the American College of Sports Medicine's (ACSM's) submaximal treadmill running test in predicting VO2max. Twenty-one moderately well-trained men aged 18-34 years performed 1 maximal treadmill test to determine maximal oxygen uptake (M VO2max) and 2 submaximal treadmill tests using 4 stages of continuous submaximal exercise. Estimated VO2max was predicted by extrapolation to age-predicted maximal heart rate (HRmax) and calculated in 2 ways: using data from all submaximal stages between 110 b·min(-1) and 85% HRmax (P VO2max-All), and using data from the last 2 stages only (P VO2max-2). The measured VO2max was overestimated by 3% on average for the group but was not significantly different to predicted VO2max (1-way analysis of variance [ANOVA] p = 0.695; M VO2max = 53.01 ± 5.38; P VO2max-All = 54.27 ± 7.16; P VO2max-2 = 54.99 ± 7.69 ml·kg(-1)·min(-1)), although M VO2max was not overestimated in all the participants--it was underestimated in 30% of observations. Pearson's correlation, standard error of estimate (SEE), and total error (E) between measured and predicted VO2max were r = 0.646, 4.35, 4.08 ml·kg(-1)·min(-1) (P VO2max-All) and r = 0.642, 4.21, 3.98 ml·kg(-1)·min(-1) (P VO2max-2) indicating that the accuracy in prediction (error) was very similar whether using P VO2max-All or P VO2max-2, with up to 70% of the participants predicted scores within 1 SEE (～4 ml·kg(-1)·min(-1)) of M VO2max. In conclusion, the ACSM equation provides a reasonably good estimation of VO2max with no difference in predictive accuracy between P VO2max-2 and P VO2max-All, and hence, either approach may be equally useful in tracking an individual's aerobic fitness over time. However, if a precise knowledge of VO2max is required, then it is recommended that this be measured directly.     

Aging and factors related to running economy

The purpose of this study was to investigate the relationship that age has on factors affecting running economy (RE) in competitive distance runners. Fifty-one male and female subelite distance runners (Young [Y]: 18-39 years [n = 18]; Master [M]: 40-59 years [n = 22]; and Older [O]: 60-older [n = 11]) were measured for RE, step rate, lactate threshold (LT), VO2max, muscle strength and endurance, flexibility, power, and body composition. An RE test was conducted at 4 different velocities (161, 188, 215, and 241 m·min(-1)), with subjects running for 5 minutes at each velocity. The steady-state VO2max during the last minute of each stage was recorded and plotted vs. speed, and a regression equation was formulated. A 1 × 3 analysis of variance revealed no differences in the slopes of the RE regression lines among age groups (y = 0.1827x - 0.2974; R2 = 0.9511 [Y]; y = 0.1988x - 1.0416; R2 = 0.9697 [M]; y = 0.1727x + 3.0252; R2 = 0.9618 [O]). The VO2max was significantly lower in the O group compared to in the Y and M groups (Y = 64.1 ± 3.2; M = 56.8 ± 2.7; O = 44.4 ± 1.7 mlO2·kg(-1)·min(-1)). The maximal heart rate and velocity @ LT were significantly different among all age groups (Y = 197 ± 4; M = 183 ± 2; O = 170 ± 6 b·min(-1) and Y = 289.7 ± 27.0; M = 251.5 ± 32.9; O = 212.3 ± 24.6 m·min(-1), respectively). The VO2max @ LT was significantly lower in the O group compared to in the Y and M groups (Y = 50.3 ± 2.0; M = 48.8 ± 2.9; O = 34.9 ± 3.2 mlO2·kg(-1)·min(-1)). The O group was significantly lower than in the Y and M groups in flexibility, power, and upper body strength. Multiple regression analyses showed that strength and power were significantly related to running velocity. The results from this cross-sectional analysis suggest that age-related declines in running performance are associated with declines in maximal and submaximal cardiorespiratory variables and declines in strength and power, not because of declines in running economy.     

Energy expenditure during tennis play: a preliminary video analysis and metabolic model approach

The aim of this study was to estimate, using video analysis, what proportion of the total energy expenditure during a tennis match is accounted for by aerobic and anaerobic metabolism, respectively. The method proposed involved estimating the metabolic power (MP) of 5 activities, which are inherent to tennis: walking, running, hitting the ball, serving, and sitting down to rest. The energy expenditure concerned was calculated by sequencing the activity by video analysis. A bioenergetic model calculated the aerobic energy expenditure (EEO2mod) in terms of MP, and the anaerobic energy expenditure was calculated by subtracting this (MP - EEO2mod). Eight tennis players took part in the experiment as subjects (mean ± SD: age 25.2 ± 1.9 years, weight 79.3 ± 10.8 kg, VO2max 54.4 ± 5.1 ml·kg(-1)·min(-1)). The players started off by participating in 2 games while wearing the K4b2, with their activity profile measured by the video analysis system, and then by playing a set without equipment but with video analysis. There was no significant difference between calculated and measured oxygen consumptions over the 16 games (p = 0.763), and these data were strongly related (r = 0.93, p < 0.0001). The EEO2mod was quite weak over all the games (49.4 ± 4.8% VO2max), whereas the MP during points was up to 2 or 3 times the VO2max. Anaerobic metabolism reached 32% of the total energy expenditure across all the games 67% for points and 95% for hitting the ball. This method provided a good estimation of aerobic energy expenditure and made it possible to calculate the anaerobic energy expenditure. This could make it possible to estimate the metabolic intensity of training sessions and matches using video analysis.     

Whichever the initial training status,any increase in velocity at lactate threshold appears as a major factor in improved time to exhaustion at the same severe velocity after training

The first purpose of this study was to assess the eventual training adaptations in the time to exhaustion at the same severe velocity occurring after severe interval-training programs in few- and well-trained subjects. In the event of such training adaptations, the second purpose was to identify the discriminant factors of performance improvement according to the initial training status. Seven few- and six well-trained subjects performed: firstly, an incremental test to determine the maximal oxygen consumption (VO2max), the energy cost of running (ECR), the velocity associated with the achievement of VO2max (vVO2max) and the lactate threshold (LT expressed in VO2, km x h(-1), % vVO2max); secondly, an all-out test at the velocity corresponding to the midway between vLT and vVO2max (vdelta50) to determine the time to exhaustion (tmax); such tests were carried out before and after 4- and 8-week severe interval-training programs. In the few-trained subjects, all factors of performance (i.e., VO2max, ECR, vVO2max, LT expressed in VO2, km x h(-1), % vVO2max) and tmax at the pre-training vdelta50 were improved after training (+8, -8, +7, +9, +14, +6% and +79%, respectively); only the increase in vLT was related to the one in tmax (r = 0.714, p < or = 0.05, n = 7). In the well-trained subjects, only vVO2max was improved (+3%) due to the decrease in ECR (-3%), tmax at the pre-training vdelta50 did not vary after training; only the three subjects (over six) who improved their vLT (+0.5, +0.5, +0.8 km x h(-1), respectively) improved their tmax (+10, +24, +101%, respectively) (r = 0.895, p < or = 0.01, n = 6). So, whichever the initial training status, any training-induced adaptation in vLT appeared as a major factor of performance improvement especially at supra-LT velocities.     

Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer.

The purpose of this investigation was to test whether the concept of critical power used in previous studies could be applied to the field of competitive swimming as critical swimming velocity (vcrit). The vcrit, defined as the swimming velocity over a very long period of time without exhaustion, was expressed as the slope of a straight line between swimming distance (dlim) at each speed (with six predetermined speeds) and the duration (tlim). Nine trained college swimmers underwent tests in a swimming flume to measure vcrit at those velocities until the onset of fatigue. A regression analysis of dlim on tlim calculated for each swimmer showed linear relationships (r2 greater than 0.998, P less than 0.01), and the slope coefficient signifying vcrit ranged from 1.062 to 1.262 m.s-1 with a mean of 1.166 (SD 0.052) m.s-1. Maximal oxygen consumption (VO2max), oxygen consumption (VO2) at anaerobic threshold, and the swimming also velocity at the onset of blood lactate accumulation (vOBLA) were also determined during the incremental swimming test. The vcrit showed significant positive correlations with VO2 at anaerobic threshold (r = 0.818, P less than 0.01), vOBLA (r = 0.949, P less than 0.01) and mean velocity of 400 m freestyle (r = 0.864, P less than 0.01). These data suggested that vcrit could be adopted as an index of endurance performance in competitive swimmers.     

The energetics of middle-distance running

In order to assess the relative contribution of aerobic processes to running velocity (v), 27 male athletes were selected on the basis of their middle-distance performances over 800, 1500, 3000 or 5000 m, during the 1987 track season. To be selected for study, the average running velocity (v) corresponding to their performances had to be superior to 90% of the best French v of the season. Maximum O2 consumption (VO2max) and energy cost of running (C) had been measured within the 2 months preceding the track season, which, together with oxygen consumption at rest (VO2rest) allowed us to calculate the maximal v that could be sustained under aerobic conditions: vamax = (VO2max - VO2rest) x C-1. The treadmill running v corresponding to a blood lactate of 4 mmol.l-1 (vla4), was also calculated. In the whole group, C was significantly related to height (r = -0.43; P less than 0.03). Neither C nor VO2max (with, in this case, the exception of the 3000 m athletes) were correlated to v. On the other hand, vamax was significantly correlated to v over distances longer than 800 m. These v were also correlated to vla4. However vla4 occurred at 87.5% SD 3.3% of vamax, this relationship was interpreted as being an expression of the correlation between vamax and v. Calculation of vamax provided a useful means of analysing the performances. At the level of achievement studied, v sustained over 3000 m corresponded to vamax.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of high-intensity interval training on cardiovascular function, VO2max, and muscular force

The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (VO2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), VO2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p < 0.05) improvements in VO2max, O2 pulse, and Wingate-derived power output with HIIT. The magnitude of improvement in VO2max was related to baseline VO2max (r = -0.44, p = 0.05) and fatigue index (r = 0.50, p < 0.05). No change (p > 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced VO2max and O2 pulse and power output in active men and women.     

Determination of the velocity associated with the longest time to exhaustion at maximal oxygen uptake

The so-called velocity associated with VO2max, defined as the minimal velocity which elicits VO2max in an incremental exercise protocol (v(VO2max)), is currently used for training to improve VO2max. However, it is well known that it is not the sole velocity which elicits VO2max and it is possible to achieve VO2max at velocities lower and higher than v(VO2max). The goal of this study was to determine the velocity which allows exercise to be maintained the longest time at v(VO2max). Using the relationship between time to exhaustion at VO2max in the all-out runs at 90%, 100%, 120% and 140% of v(VO2max) and distance run at VO2max, the velocity which elicits the longest time to exhaustion at VO2max (CV') was determined. For the six subjects tested (physical education students), this velocity was not significantly different from v(VO2max) (16.96+/-0.92 km x h(-1) vs 17.22+/-1.12 km x h(-1), P = 0.2 for CV' and v(VO2max), respectively) and these two velocities were correlated (r = 0.88, P = 0.05).     

Development of a submaximal test to predict elliptical cross-trainer VO2max

The purpose of this study was to develop an equation to predict VO2max from a submaximal elliptical cross-trainer test. Fifty-four apparently healthy subjects (25 men and 29 women, mean +/- SD age: 29.5 +/- 7.1 years, height: 173.3 +/- 12.6 cm, weight: 72.3 +/- 7.9 kg, percent body fat: 17.3 +/- 5.0%, and elliptical cross-trainer VO2max: 43.9 +/- 7.2 ml x kg(-1) x min(-1)) participated in the study and were randomly assigned to an original sample group (n = 40) and a cross-validation group (n = 14). Each subject completed an elliptical cross-trainer submaximal (3 5-minute submaximal stages) and a VO2max test on the same day, with a 15-minute rest period in between. Stepwise multiple regression analyses were used to develop an equation for estimating elliptical cross-trainer VO2max from the data of the original sample group. The accuracy of the equation was tested by using data from the cross-validation group. Because there was no shrinkage in R2 between the original sample group and the cross-validation group, data were combined in the final prediction equation (R2 = 0.732, standard error of the estimate = 3.91 ml x kg(-1) x min(-1), p < 0.05): VO2max = 73.676 + 7.383(gender) - 0.317(weight) + 0.003957(age x cadence) - 0.006452(age x heart rate at stage 2). The correlation coefficient between the predicted and measured VO2max values was r = 0.86. Dependent t-tests resulted in no significant differences (p > 0.05) between predicted (43.8 ml x kg(-1) x min(-1)) and measured (43.9 ml x kg(-1) x min(-1)) VO2max measurements. Results indicate that the protocol and equation developed in the current study can be used by exercise professionals to provide acceptably accurate estimates of VO2max in non-laboratory-based settings.     

Running economy and maximal oxygen consumption after 4 weeks of oral Echinacea supplementation

The purpose of this investigation was to determine the effects of 4 weeks of oral Echinacea (ECH) supplementation on erythropoietin (EPO), red blood cell (RBC) count, running economy (RE), and VO2max. Twenty-four men aged 24.9 ± 4.2 years, height 178.9 ± 7.9 cm, weight 87.9 ± 14.6 kg, body fat 19.3 ± 6.5% were grouped using a double-blind design and self-administered an 8,000-mg·d(-1) dosage of either ECH or placebo (PLA) in 5 × 400 mg × 4 times per day for 28 days. Blood samples were collected and analyzed for RBCs and EPO using automated flow cytometery and enzyme-linked immunosorbent assay. Maximal graded exercise tests (GXTs) were administered to measure VO2max, RE, and heart-rate responses. Analysis of variance was used to determine statistically significant differences (P ≤ 0.05). The EPO increased significantly in ECH at 7 days (ECH: 15.75 ± 0.64, PLA: 10.01 ± 0.73 mU·ml(-1)), 14 days (ECH: 18.88 ± 0.71, PLA: 11.02 ± 0.69 mU·ml(-1)), and 21 days (ECH: 16.06 ± 0.55, PLA: 9.20 ± 0.55 mU·ml(-1)). VO2max increased significantly in ECH (ECH: 1.47 ± 1.28, PLA: -0.13 ± 0.52%). Running economy improved significantly in ECH as indicated by a decrease in submaximal VO2max during the first 2 stages of the GXT (stage 1: ECH -1.50 ± 1.21, PLA 0.60 ± 1.95%; stage 2: ECH -1.67 ± 1.43, PLA 0.01 ± 1.03%). These data suggest that ECH supplementation results in significant increases in EPO, VO2max, and running economy.     

A protocol of intermittent exercise (shuttle runs) to train young basketball players

The purpose of this study was to set up a protocol of intermittent exercise to train young basketball players. Twenty-one players were asked to complete (a) an incremental test to determine maximal oxygen uptake (VO2max), the speed at the ventilatory threshold (vthr) and the energy cost of "linear" running (Cr) and (b) an intermittent test composed of 10 shuttle runs of 10-second duration and 30-seconds of recovery (total duration: about 6 minutes). The exercise intensity (the running speed, vi) was set at 130% of vthr. During the intermittent tests, oxygen uptake (VO2) and blood lactate concentration (Lab) were measured. The average pretraining VO2 calculated for a single bout (131 ± 9 ml · min(-1) kg(-1)) was about 2.4 times greater than the subjects' measured VO2max (54.7 ± 4.6 ml · min(-1) · kg(-1)). The net energy cost of running (9.2 ± 0.9 J · m(-1) · kg(-1)) was about 2.4 times higher than that measured at constant "linear" speed (3.9 ± 0.3 J · m(-1) · kg(-1)). The intermittent test was repeated after 7 weeks of training: 9 subjects (control group [CG]) maintained their traditional training schedule, whereas for 12 subjects (experimental group [EG]) part of the training was replaced by intermittent exercise (the same shuttle test as described above). After training, the VO2 measured during the intermittent test was significantly reduced (p < 0.05) in both groups (-10.9% in EG and - 4.6 in CG %), whereas Lab decreased significantly only for EG (-31.5%). These data suggest that this training protocol is effective in reducing lactate accumulation in young basketball players.     

Seasonal aerobic performance variations in elite soccer players

The purpose of this study was to examine the seasonal changes in body composition and aerobic performance in elite soccer players. Twelve elite professional soccer players (aged 25 6 5 years, weight 75.7 6 5.3 kg, height 1.79 6 0.06 m) were measured for body fat (%), maximum oxygen consumption (VO2max), running velocity at VO2max (VO2max), running velocity at a fixed blood lactate concentration of 4 mmol · L21 (v-4 mM) at the start of the preseason period, at the beginning of the competitive period, and at midseason. VO2max, v-4 mM, and vVO2max increased significantly (p , 0.05) by 4.5, 10.5, and 7.8,respectively, after the preseason period. Thereafter, the aerobic performance parameters remained relatively constant, with no significant changes throughout the competitive period. The results of this study suggest that moderate improvements were observed in VO2max, and the %VO2max at 4 v-4 mM, whereas higher improvements were observed in VO2max and v-4 mmol · L21 after the preseason training period. On the other hand, during the competitive period, aerobic performance remained unchanged.In addition, this study suggests that heart rate, lactate, vVO2, and VO2max are useful and practical predictors that help monitor aerobic performance changes during a soccer season.     

Relationship between anaerobic cycling tests and mountain bike cross-country performance

Despite its apparent relevance, there is no evidence supporting the importance of anaerobic metabolism in Olympic crosscountry mountain biking (XCO). The purpose of this study was to examine the correlation between XCO race time and performance indicators of anaerobic power. Ten XCO riders (age: 28 ± 5 years; weight: 68.7 ± 7.7 kg; height: 177.9 ± 7.4 cm; estimated body fat: 5.7 ± 2.8%; estimated ·VO?max: 68.4 ± 5.7 ml·kg?1·min?1) participating in the Lagos Mountain Bike Championship (Brazil) completed 2 separate testing sessions before the race. In the first session, after anthropometric assessments were performed, the cyclists completed a single 30-second Wingate (WIN) test and an intermittent tests consisting of 5 × 30-second WIN tests (50% of the single WIN load) with 30 seconds of recovery between trials. In the second session, the riders performed a maximal incremental test. A significant correlation was found between race time and maximal power on the 5× WIN test (r = -0.79, IC(95%) -0.94 to -0.32, p = 0.006) and the mean average power on the 5× WIN test normalized by body mass (r = -0.63, IC(95%) -0.90 to -0.01, p = 0.048). The finding of the study supports the use of anaerobic tests for assessing mountain bikers participating in XCO competitions and suggests that anaerobic power is an important determinant of performance.     

Effects of gradual-elastic compression stockings on running economy, kinematics, and performance in runners

We investigated the effect of gradual-elastic compression stockings (GCSs) on running economy (RE), kinematics, and performance in endurance runners. Sixteen endurance trained athletes (age: 34.73 ± 6.27 years; VO2max: 62.83 ± 9.03 ml·kg(-1)·min(-1); 38 minutes in 10 km; 1 hour 24 minutes in half marathon) performed in random order 4 bouts of 6 minutes at a recent half-marathon pace on a treadmill to evaluate RE with or without GCSs. Subsequently, 12 athletes were divided into 2 equal groups matched by their VO2max, and they performed a time limit test (T(lim)) on a treadmill at 105% of a recent 10-km pace with or without GCSs for evaluation of physiological responses and running kinematics. There were no significant differences in the RE test in all of the variables analyzed for the conditions, but a moderate reproducibility for some physiological responses was detected in the condition with GCSs. In the T(lim), the group that wore GCSs reached a lower % of maximum heart rate (HRmax) compared with the control group (96.00 ± 2.94 vs. 99.83 ± 0.40) (p = 0.01). Kinematics did not differ between conditions during the T(lim) (p > 0.05). There were improvement trends for time to fatigue (337 vs. 387 seconds; d = 0.32) and a lower VO2peak (≈53 vs. 62 ml·kg(-1)·min(-1); d = 1.19) that were detected with GCSs during the T(lim). These results indicate that GCSs reduce the % of HRmax reached during a test at competition pace. The lower reproducibility of the condition with GCSs perhaps suggests that athletes may possibly need an accommodation period for systematically experiencing the benefits of this garment, but this hypothesis should be further investigated.     

The effects of static stretching on running economy and endurance performance in female distance runners during treadmill running

Stretching can lead to decreased muscle stiffness and has been associated with decreased force and power production. The purpose of this study was to investigate the acute effects of static stretching (SS) on running economy and endurance performance in trained female distance runners. Twelve long distance female (30 ± 9 years) runners were assessed for height (159.4 ± 7.4 cm), weight (54.8 ± 7.2 kg), % body fat (19.7 ± 2.8%), and maximal oxygen consumption (VO2max: 48.4 ± 5.1 ml·kg(-1)·min(-1)). Participants performed 2 sessions of 60-minute treadmill runs following a randomly assigned SS protocol or quiet sitting (QS). During the first 30 minutes (running economy), expired gases, heart rate (HR), and rating of perceived exertion (RPE) were recorded while the participant ran at 65% VO2max. During the final 30 minutes (endurance performance), distance covered, speed, HR, and RPE were recorded while the participant attempted to cover as much distance as possible. Repeated measures analyses of variance were performed on the data. Significance was accepted at p < 0.05. The SS measured by sit-and-reach increased flexibility (SS: 29.8 ± 8.3 vs. QS: 33.1 ± 8.1 cm) but had no effect on running economy (VO2: 33.7 ± 3.2 vs. 33.8 ± 2.3 ml·kg(-1)·min(-1)), calorie expenditure (270 ± 41 vs. 270 ± 41 kcal), HR (157 ± 10 vs. 160 ± 12 b·min(-1)), or endurance performance (5.5 ± 0.6 vs. 5.5 ± 0.7 km). These findings indicated that stretching did not have an adverse effect on endurance performance in trained women. This suggests that the performance decrements previously associated with stretching may not occur in trained women.