Peak Treadmill Velocity Research Articles

Aerobic adaptations following two iso-effort training programs: an intense continuous and a high-intensity interval.

The intensity of the training stimulus and the effort exerted (regarded as an index of internal load) to complete an exercise session are driving forces for physiological processes and long-term training adaptations. This study compared the aerobic adaptations following two iso-effort, ratings of perceived exertion (RPE)-based training programs, an intense continuous (CON) and a high-intensity interval (INT). Young adults were assigned to a CON (n=11) or an INT (n=13) training group to perform 14 training sessions within 6 weeks. The INT group performed running bouts (9.3±4.4 repetitions) at 90% of peak treadmill velocity (PTV) with bout duration equal to 1/4 of time to exhaustion at this speed (134.2±27.9 s). The CONT group ran (1185.0±487.6 s) at a speed corresponding to -2.5% of critical velocity (CV; 80.1%±3.0% of PTV). Training-sessions were executed until RPE attained 17 on the Borg scale. VO2max, PTV, CV, lactate threshold velocity (vLT), and running economy were assessed pre-, mid-, and post-training. Both CONT and INT methods increased (p<0.05) VO2max (INT: 57.7±8.1-61.41±9.2; CONT: 58.1±7.5-61.1±6.3 mL kg-1 min-1), PTV (INT: 14.6±1.8-15.7±2.1; CONT: 15.0±1.7-15.7±1.8 km h-1), CV (INT: 11.8±1.4-12.8±1.8; CONT: 12.2±1.6-12.9±1.7 km h-1), and vLT (INT: 9.77±1.1-10.8±1.4; CONT: 10.4±1.4-11.0±1.8 km h-1) with no differences (p>0.05) between them; running economy remained unchanged. The continuous training method, when matched for effort and executed at relatively high intensity at the upper boundaries of the heavy-intensity domain (∼80% of PTV), confers comparable aerobic adaptations to those attained after a high-intensity interval protocol following a short-term training period.

Purslane supplementation lowers oxidative stress, inflammatory and muscle damage biomarkers after high-intensity intermittent exercise in female runners

Background: The aim of this study was to determine the effect of purslane supplementation on oxidative stress, inflammation and muscle damage biomarkers after completing high-intensity interval exercise (HIIE). Methods: Nine healthy female runners completed a HIIE treadmill protocol comprising 1 min at 100% of the peak treadmill velocity attained in a preliminary exhaustive incremental treadmill test, interspersed by 1 min of passive recovery, until they had run for 2.5 km. Athletes repeated this test following 10 days of supplementation with 1000 mg per day of purslane. Results: At baseline (i.e., absence of purslane supplementation) the HIIE protocol increased 9-HODE (p &lt; 0.001), 13-HODE (p &lt; 0.001), IL-17 (p &lt; 0.001), TNF-α (p &lt; 0.001), and LDH (p &lt; 0.001). After purslane consumption, resting 9-HODE, 13-HODE, IL-17, TNF-α, and LDH were lowered (p &lt; 0.001) and IL-10 was increased (p &lt; 0.001) compared to before purslane supplementation. After purslane consumption and following the HIIE protocol, the responses of these biomarkers were lower compared to baseline (p &lt; 0.001). Conclusion: Ten days of purslane supplementation blunted the perturbation to biomarkers of oxidative stress, inflammation and muscle damage in female runners completing a HIIE protocol.

Is the metabolic power paradigm ecologically valid within elite Gaelic football?

To examine the association between the metabolic power paradigm during training and match-play and objective aerobic fitness measures within elite Gaelic football players. Twenty-five elite Gaelic football players completed objective physiological testing for VO2max, vVO2max, Peak treadmill Velocity (PTV), Running economy (RE) and selected blood lactate concentrations of 2 mmol L−1 (S2) and 4 mmol L−1 (S4). Aerobic testing was performed at the start of the season and at the halfway point of the season. Training and match-play running performances were recorded across the period with global positioning system technology (GPS; 4-Hz; VX Sport, Lower Hutt, New Zealand). Instantaneous raw velocity data were obtained from the GPS and exported to a customised spreadsheet which provided estimations of total distance (m), high-speed running distance (m; 17 km h−1), very-high-speed running distance (m; 22 km h−1), total accelerations (n), acceleration distance (m), peak and mean velocity (km h−1). Furthermore, changes in velocity were analysed which allowed for the assessment of the metabolic power paradigm during these training and match-play events. Players average metabolic power (Pmet; W Kg−1) observed to have a large association with VO2max (r = 0.76–0.88) and velocity at VO2max (r = 0.72–0.91) in training and match situations. Interestingly, peak treadmill velocity showed a moderate association with training and match-play high metabolic power distance (r = 0.56–0.76). Large associations were observed between high power distance during match and training categories and velocity at VO2max (r = 0.76–0.89). Furthermore, high power distance was observed to have a large association with peak treadmill velocity (r = 0.72–0.91) in training and match situations with lactate variables showing a small to moderate association with metabolic power variables. The current investigation is the first to provide evidence towards the ecological validity of the metabolic power paradigm to assess aerobic fitness within elite Gaelic football. Practitioners should consider the association between aerobic fitness and specific metabolic load paradigm variables within their monitoring system as a potential means to understand the impact of training plans within elite Gaelic football players.

Influence of Dietary Nitrate Supplementation on High-Intensity Intermittent Running Performance at Different Doses of Normobaric Hypoxia in Endurance-Trained Males.

This study investigated whether supplementation with nitrate-rich beetroot juice (BR) can improve high-intensity intermittent running performance in trained males in normoxia and different doses of normobaric hypoxia. Eight endurance-trained males (V˙O2peak, 62 ± 6ml·kg-1·min-1) completed repeated 90 s intervals at 110% of peak treadmill velocity, from an initial step incremental test, interspersed by 60s of passive recovery until exhaustion (Tlim). Participants completed the first three experimental trials during days 3, 5, and 7 of BR or nitrate-depleted beetroot juice (PLA) supplementation and completed the remaining experimental visits on the alternative supplement following at least 7 days of washout. The fraction of inspired oxygen during visits 1-3 was either 0.209, 0.182, or 0.157, equivalent to an altitude of 0, 1,200, and 2,400 m, respectively, and this order was replicated on visits 4-6. Arterial oxygen saturation declined dose dependently as fraction of inspired oxygen was lowered (p < .05). Plasma nitrite concentration was higher pre- and postexercise after BR compared with PLA supplementation (p < .05). There was no difference in Tlim between PLA and BR at 0 m (445 [324, 508] and 410 [368, 548] s); 1,200 m (341 [270, 390] and 332 [314, 356] s); or 2,400 m (233 [177, 373] and 251 [221, 323] s) (median and [interquartile range]; p > .05). The findings from this study suggest that short-term BR supplementation does not improve high-intensity intermittent running performance in endurance-trained males in normoxia or at doses of normobaric hypoxia that correspond to altitudes at which athletes typically train while on altitude training camps.

Methods of Monitoring Training Load and Their Association With Changes Across Fitness Measures in Hurling Players.

Malone, S, Hughes, B, Collins, K, and Akubat, I. Methods of monitoring training load and their association with changes across fitness measures in hurling players. J Strength Cond Res 34(1): 225-234, 2020-The aim of the current investigation was to assess the dose-response relationship for various methods of monitoring training load (TL) and changes in aerobic and anaerobic fitness in hurling players. Training and match load measures were collected from 30 hurling players (speed at different blood lactate [vLT, vOBLA], maximal oxygen uptake [VO2max], speed at VO2max [vVO2max], peak treadmill velocity [PTV] running economy [RE] Yo-Yo intermittent recovery test (Yo-YoIR1, Yo-YoIR2), speed at 5, 10 , 20 m, and repeated sprint ability [6 × 35 m]) before and after during a 12-week in-season period. Mean weekly training and match loads as determined by s-RPE, bTRIMP, luTRIMP, eTRIMP, iTRIMP, and gTRIMP were correlated with each other, percentage change in VO2max, vVO2max, RE, PTV, the speed at blood lactate concentrations of 2 mmol·L (vLT) and 4 mmol·L (vOBLA), and YoYoIR1, Yo-YoIR2 performance. iTRIMP showed a trivial association with s-RPE and a small to moderate association with other heart rate-based methods. Small to large changes (effect size: 0.38-1.12) were observed in aerobic and anaerobic fitness measures were observed across the 12-week period. Trivial to very large associations (r = 0.11-0.78) were observed between TL variables and changes in fitness depending on the variable analyzed. iTRIMP was shown to have large to very large associations with changes in vOBLA {r = 0.78 (95% confidence interval [CI]: 0.71-0.88)}, VO2max (r = 0.77 [95% CI: 0.68-0.82]), RE (r = 0.77 [95% CI: 0.67-0.82]), Yo-YoIR1 (r = 0.69 [95% CI: 0.51-0.72]), and RSAb (r = 0.66 [95% CI: 0.60-0.72]) with moderate associations reported between iTRIMP and other variables. All other measures of TL showed trivial to moderate associations (r = 0.11-0.66). The current investigation shows that fully individualized training load (iTRIMP) measures may potentially offer a better understanding of dose-response relationships when compared with subjective and nonindividualized measures of TL to changes in aerobic and anaerobic fitness in team sports athletes; as such, it may be suggested that practitioners should use individualized measures of TL assessment within their day-to-day practices.

Effect of Training Load Distribution on Aerobic Fitness Measures in Hurling Players

Malone, S, Hughes, B, and Collins, K. Effect of training load distribution on aerobic fitness measures in hurling players. J Strength Cond Res 33(3): 825-830, 2019-The aim of the current investigation was to quantify the training intensity distribution of hurling players and their association with changes in aerobic fitness measures within hurling players. Thirty hurling players (n = 30; age 26.5 ± 3.2 years; height 178.9 ± 3.2 cm; body mass 81.5 ± 4.5 kg) were observed during the pre-championship training period (12 weeks). Aerobic fitness measures (V[Combining Dot Above]O2max), peak treadmill velocity (km·h), heart rates (HRs) at 2 and 4 mmol·L blood lactate concentrations, and Yo-Yo intermittent recovery test performance (Yo-YoIR1) were assessed before and after the training period. Training intensities were categorized using 3 individualized HR zones based on the following criteria: low intensity (≤HR 2 mmol·L), moderate intensity (between HR 2 and 4 mmol·L), and high intensity (≥HR 4 mmol·L). Analysis of 1,025 individual training sessions showed that players spent 58.1 ± 2.5%, 24.3 ± 2.9%, and 17.6 ± 1.3% of time in the low-, moderate-, and high-intensity zones, respectively. The training time spent at high intensity (Zone 3) showed moderate-to-large associations with improvements in S2 (r = 0.80; p = 0.04) and S4 (r = 0.58; p = 0.03). Similar trends were observed for time spent in high intensity and improvements in V[Combining Dot Above]O2max (r = 0.77; p = 0.001) and Yo-YoIR1 performance (r = 0.65; p = 0.05). Hurling players have been shown to spend the majority of training time in low (≤ HR 2 mmol·L) to moderate intensity (between HR 2 and 4 mmol·L) training. However, only the time spent at high intensity (≥90% of maximal HR) was related to changes in aerobic fitness. These results support the usefulness of the quantification of aerobic training load using HR. The study also supports the efficacy of spending elements of training time within the high-intensity zone to increase hurling player's aerobic fitness characteristics.

Effects of carbohydrate mouth rinse and caffeine on high-intensity interval running in a fed state.

The current study aims to identify if mouth rinsing with a 6% carbohydrate mouth-rinse (CMR) solution and mouth rinsing and ingestion of caffeine (CMR+CAFF) can affect exercise performance during steady-state (SS) running and high-intensity intervals (HIIT) in comparison with a 0% control solution (PLA) when in a fed state. Eight recreationally trained males completed 3 trials (CMR, CMR+CAFF, and PLA) of 45 min SS running and an HIIT protocol (90% peak treadmill velocity) until fatigue in a double blinded, repeated-measures study. Participants ingested a capsule of either CAFF or PLA before and after SS. Participants received a 25-mL bolus of carbohydrate solution (CMR and CMR+CAFF trials) or taste-matched PLA (PLA trial) prior to HIIT protocol and after every second effort. Heart rate and lactate responses were recorded throughout the SS and HIIT protocol. CMR+CAFF was significantly different when compared with PLA (p = 0.001; Cohens d = 1.34) and CMR (p = 0.031; Cohens d = 0.87) in relation to distance covered before fatigue. Although there was no significant difference between CMR and PLA, there was a small benefit for CMR (p = 0.218; Cohens d = 0.46). Results indicate that CMR and ingestion of CAFF leads to improvements in performance during interval sessions while participants were in a fed state. These findings indicate that the regular use of CMR can decrease the risk of gastrointestinal distress reported by athletes, which can be applicable to athletes in a real-world setting.

Effects of continuous and intermittent endurance exercise in autonomic balance, rating perceived exertion and blood lactate levels in healthy subjects

PurposeThe aim of this study was to determinate the changes in the Autonomic Balance, Rating Perceived Exertion (RPE) and blood lactate after continuous versus intermittent exercise protocols. MethodsSeven active and healthy male (33±5.1 years) participated in the study. Each subject performed two exercise protocols: (i) a continuous exercise at 110% of the lactate threshold (CONT). The CONT protocol consisted in continuous running, and the distance covered was the same in meters as it was in the intermittent session, and (ii) an intermittent exercise at 100% of the Peak Treadmill Velocity (INTT). The protocol consisted of 30min of 15s running, interspersed with 15s of passive rest. Autonomic balance was assessed through the LF/HF ratio, before beginning the exercises, immediately finishing the exercises and 24h post-exercise; RPE was evaluated every 5min in each exercise protocol; and blood lactate was measured immediately after both protocols. Alpha level was set at P≤.05. ResultsAutonomic balance did not show significant differences between protocols (P=.60). RPE during INTT exercise was significantly higher than CONT exercise (P=.01). Blood lactate levels after exercise did not show significant differences (P=.68). Heart rate variability parameters in the time domain (mean RR and pNN50) show no statistical differences between both protocols pre and 24h post exercise (P=.24 and P=.61, respectively). ConclusionsThe data suggest that intermittent exercise is perceived more intense than continuous, although both protocols showed similar internal loads in autonomic balance and blood lactate levels.

Muscle Oxygenation and Blood Volume Reliability during Continuous and Intermittent Running

The reliability of near infrared spectroscopy derived tissue oxygenation index (TOI) and total haemoglobin concentration (tHb) were examined during continuous (CR) and interval (INT) running. In a repeated measures design, 10 subjects twice performed 30 min of CR at 70% of their peak treadmill velocity, followed by 10 bouts of INT at 100%. Between trial reliability of mean and amplitude changes in TOI and tHb during CR were determined. Muscle de-oxygenation and re-oxygenation rates during INT were calculated using 3 analytical methods; i) linear modelling, ii) minimum and maximum values during work/rest intervals, and iii) mean values during work/rest intervals. Reliability was assessed using coefficient of variation (CV; %). During CR, mean TOI was more reliable (3.5%) compared with TOI amplitude change (34.7%), while mean tHb (12%) was similar to both absolute (9.2%) and relative (10.2%) amplitude changes. During INT, de-oxygenation rates analysed via linear modelling produced the lowest CV (7.2%), while analysis using min-max values produced the lowest CV (9.3%) for re-oxygenation rates. In conclusion, while the variables demonstrated CVs lower than reported changes in training-induced adaptations and/or differences between athletes and controls (23- 450%), practitioners are encouraged to consider the advantages/disadvantages of each method when performing their analysis.

Outcome Measures and Rehabilitation Treatment in Patients Affected by Charcot-Marie-Tooth Neuropathy

: We evaluated the sensitivity of various rehabilitation and lung function scales to detect differences between people with Charcot-Marie-Tooth (CMT) disease and healthy controls. We also studied whether these measurements are sensitive to disclose changes in patients with CMT disease after rehabilitative treatment. : Eight patients with different types of CMT participated in the study. Data were gathered at baseline; at the end of the treadmill training, stretching, respiratory, and proprioceptive exercise (TreSPE) treatment period; and after a washout period of 6 mos. The following instruments were used for data collection: Medical Research Council scale for lower limb strength; Tinetti Balance Scale; Physical Performance Battery; ankle angle, oxygen consumption, and lung function tests; peak treadmill velocity and slope; time to walk 6 m; and CMT Neuropathy Score. The participants underwent TreSPE treatment twice every week for 8 wks. : All rehabilitative measures were significantly worse in subjects with CMT disease than in healthy controls. Lung function was always normal except for the maximum expiratory pressure and maximum inspiratory pressure. No dropouts or worsening in any of the different outcome measures were observed after TreSPE. The ankle angle and the time to walk 6 m were the only measures that significantly improved after treatment. : The rehabilitative outcome measures used in this protocol are useful in detecting clinical impairment in people with CMT disease. Lung function tests were confirmed to be minimally abnormal in patients with CMT disease. The TreSPE treatment, besides being safe and well tolerated, induced some training effects in CMT neuropathy, in the absence of lung function amelioration and effort tolerance. Follow-up showed that CMT patients should be treated at least twice every year because a regression of all outcome measures to the baseline state was found after a 6-mo washout period.

The validity of incremental exercise testing in discriminating of physiological profiles in elite runners

The goal of this study was to determine whether traditional ergoespirometric incremental exercise testing carried out to the point of exhaustion could be useful in distinguishing the physiological profiles of elite runners that compete in races that lasted about 8 minutes versus those that lasted about 2 hours. Ten male marathon runners (performance time: 2:12:04, coefficient of variation (CV) = 2.33%) and 8 male 3000 m steeplechase runners (performance time: 8:37.83, CV = 2.12%) performed an incremental test on the treadmill (starting speed 10 km·h-1; increments, 2 km·h-1; increment duration, 3 min to exhaustion). Heart rate (HR), VO2, and lactate concentrations were measured at the end of each exercise level. At maximal effort, there were no differences between the groups regarding VO2max and maximal HR; however, the workload time, vVO2max and peak treadmill velocity were significantly higher in the 3000 m steeplechase group (p<0.05). At submaximal effort, there were no significant differences between groups for VO2 (ml·kg-1·min-1), HR, or lactate. Our results show that this type of testing was not sufficient for discriminating the physiological profiles of elite runners who competed in middle-distance versus long-distance events (e.g. in the marathon and the 3000 m steeplechase).

THE IMPORTANCE OF A CORRECT STUDY DESIGN TO DIFFERENTIATE BETWEEN TWO OPPOSING MODELS

Dear Editor-in-Chief: The study of McLaughlin et al. (2) used the outcomes of four different running tests (V˙O2max test, LT test, running economy (RE) test, and peak treadmill velocity (PTV) test) to predict performance in a 16-km time trial run. Linear regression analyses were used to determine which parameter best predicts 16-km running performance. Velocity at V˙O2max (r = −0.972) was found to be the strongest predictor of 16-km running performance followed by V˙O2max (r = −0.907) and PTV (r = −0.902). As velocity at V˙O2max is predicted from the V˙O2max and RE measurement, the authors concluded that the cardiovascular model (CVM) (1) explains endurance performance better than the central governor model (CGM) (4), which they argue requires that the PTV should be the premier performance predictor. Our original suggestion that PVT is linked to muscle power rather that to maximal oxygen transport (5) resulted in the development of the CGM (3,4). This model argues that exercise performance is regulated to maintain homeostasis in all bodily systems (3,4) and is not simply the result of superior muscle power as suggested by McLaughlin et al. (2), nor does this model predict that exercise performance is limited by oxygen delivery to the muscle, as suggested by the CVM. Instead the CGM argues that by recruiting the largest possible number of skeletal muscle fibers with the greatest contractile capacity, superior athletes will have the shortest foot contact times and the longest flight times (6), resulting in the highest maintainable running speeds and superior endurance performance. On the basis of their finding that "velocity at V˙O2max" had the strongest relationship with 16-km running performance, McLaughlin et al. (2) conclude that the capacity for oxygen delivery to the muscle together with RE determines endurance running performance. However, as their cross-sectional research design cannot prove causation, they cannot conclude that the CVM explains running performance better than the CGM. Furthermore, the overlap in 95% confidence intervals for velocity at V˙O2max (r = 0.92-0.99) and PTV (r = 0.74-0.96) suggests that it cannot even be reasonably concluded that velocity at V˙O2max is a better predictor of the 16-km running time than is the PTV. The main point of this letter is to point out that the study of McLaughlin et al. (2) was not designed to determine causality. To compare the predictions of the CGM and the CVM, measurements such as muscle recruitment, muscle contractility, muscle force production, foot contact, and flight times need to be measured in addition to traditional CVM variables such as V˙O2max and its derivates. In the absence of these measurements, McLaughlin et al. seem to have overinterpreted the significance of their findings to find support for the CVM. This example emphasizes the importance of designing the correct experiment to prove causality and the danger of the overinterpretation of findings from an inappropriate research design. Robert Patrick Lamberts Timothy David Noakes UCT/MRC Research Unit for Exercise Science and Sports Medicine Department of Human Biology University of Cape Town Cape Town, South Africa

RESPONSE

Dear Editor-in-Chief: Thank you for the opportunity to respond. Although we welcome a critical analysis of our work, it appears that Lamberts and Noakes have misinterpreted what we wrote. We actually concluded, "Among well-trained subjects heterogeneous in V˙O2max and running performance, velocity at V˙O2max (vV˙O2max) is the best predictor of running performance because it integrates both maximal aerobic power and economy of running" (6). This is different than concluding that "the cardiovascular model (CVM) explains endurance performance better than the central governor model (CGM)," as they have claimed we did. Lamberts and Noakes label the classic model of physiological factors that determine endurance running performance "the cardiovascular model." We do not agree with this terminology because a number of factors (V˙O2max, running economy, and fractional utilization of V˙O2max) are involved (1,4,5). Lamberts and Noakes contend that "by recruiting the largest possible number of skeletal muscle fibers with the greatest contractile capacity, superior athletes will have the shortest foot contact times and the longest flight time, resulting in superior performance." However, sprinters should be able to recruit a larger number of muscle fibers with the greatest contractile ability because they possess the highest percentage type II muscle fibers. Sprinters also have shorter foot contact times and longer flight times than distance runners (2,3). If Lambert and Noakes were correct, then sprinters would be able to achieve higher peak treadmill velocities and would have faster 16-km run times than distance runners. Because this is not the case, it appears that something is wrong with their theory. We agree that cross-sectional studies cannot prove causation. However, alterations in O2 delivery (through blood doping, erythropoietin, beta blockade, induced anemia, and breathing hypoxic gas mixtures) will impact V˙O2max and endurance performance in predictable ways (1). These findings lend credibility to the claim that V˙O2max is a determinant of distance running performance. In addition, there are logical reasons why V˙O2max, running economy, and fractional utilization of V˙O2max are causally linked to distance running performance. Regarding the claim that we have not proven or disproven the central governor model (CGM), this is true. But the burden of proof for providing evidence to back up the CGM falls on Noakes et al. because they are the leading proponents of this model. Our study was not designed to test Dr. Noakes' CGM, which proposes that a central governor in the brain limits exercise performance to protect the heart and other organ systems from damage. Our study demonstrates that the same variables (V˙O2max and running economy) that are highly correlated with the 16-km run performance are also highly correlated with peak treadmill velocity. Lamberts and Noakes state, "Nor does [our] model predict that exercise performance is limited by oxygen delivery to the muscle…." This highlights the primary difference between the classic model for explaining distance running performance and the CGM. In our view, any model that does not acknowledge O2 delivery as a determinant of endurance exercise performance is severely flawed. James E. McLaughlin Exercise Physiology Department Lynchburg College Lynchburg, VA Edward T. Howley David R. Bassett, Jr. Department of Exercise, Sport, and Leisure Studies University of Tennessee Knoxville, TN

Test of the Classic Model for Predicting Endurance Running Performance

To compare the classic physiological variables linked to endurance performance (VO2max, %VO2max at lactate threshold (LT), and running economy (RE)) with peak treadmill velocity (PTV) as predictors of performance in a 16-km time trial. Seventeen healthy, well-trained distance runners (10 males and 7 females) underwent laboratory testing to determine maximal oxygen uptake (VO2max), RE, percentage of maximal oxygen uptake at the LT (%VO2max at LT), running velocity at LT, and PTV. Velocity at VO2max (vVO2max) was calculated from RE and VO2max. Three stepwise regression models were used to determine the best predictors (classic vs treadmill performance protocols) for the 16-km running time trial. Simple Pearson correlations of the variables with 16-km performance showed vVO2max to have the highest correlation (r = -0.972) and %VO2max at the LT the lowest (r = 0.136). The correlation coefficients for LT, VO2max, and PTV were very similar in magnitude (r = -0.903 to r = -0.892). When VO2max, %VO2max at LT, RE, and PTV were entered into SPSS stepwise analysis, VO2max explained 81.3% of the total variance, and RE accounted for an additional 10.7%. vVO2max was shown to be the best predictor of the 16-km performance, accounting for 94.4% of the total variance. The measured velocity at VO2max (PTV) was highly correlated with the estimated velocity at vVO2max (r = 0.8867). Among well-trained subjects heterogeneous in VO2max and running performance, vVO2max is the best predictor of running performance because it integrates both maximal aerobic power and the economy of running. The PTV is linked to the same physiological variables that determine vVO2max.

Anaerobic Running Capacity Determined from a 3-Parameter Systems Model: Relationship with other Anaerobic Indices and with Running Performance in the 800 m-Run

The purpose of this study was to compare anaerobic running capacity (ARC, i.e., the distance that can be run using only stored energy sources in the muscle) determined from a 3-parameter systems model with other anaerobic indices and with running performance in the 800 m. Seventeen trained male subjects (.VO(2max) = 66.54 +/- 7.29 ml . min (-1) . kg (-1)) performed an incremental test to exhaustion for the determination of .VO(2max) and peak treadmill velocity (PTV), five randomly ordered constant velocity tests at 95, 100, 105, 110, and 120 % of PTV to compute ARC and oxygen deficit (O(2)def, at 110 % of PTV), and a 800-m time trial to determine running performance (mean velocity over the distance, V (800 m)) and peak blood lactate concentration ([La (-)] (b, peak)). ARC (467 +/- 123 m) was positively correlated with O(2)def (56.35 +/- 18.47 ml . kg (-1); r = 0.57; p < 0.05), but not with [La (-)] (b, peak) (15.08 +/- 1.48 mmol . l (-1); r = - 0.16; p > 0.05). The O(2) equivalent of ARC (i.e., the product of ARC by the energy cost of running; 103.74 +/- 28.25 ml . kg (-1)), which is considered as an indirect estimation of O(2)def, was significantly higher than O(2)def (p < 0.01, effect size = 1.99). It was concluded that ARC is partially determined by anaerobic pathway, but that it probably does not provide an accurate measure of anaerobic capacity, if, however, O(2)def can be considered as a criterion measure for it.

Is aerobic endurance a determinant of cardiac autonomic regulation?

The aim of this study was to determine if subjects matched for VO2max but with differing aerobic endurance displayed similar heart rate variability (HRV) at rest and heart rate recovery (HRR) after maximal exercise. We hypothesized that the higher the aerobic endurance, the higher the HRV and the faster the HRR. Twenty-eight well trained middle- and long-distance runners (24 men and 4 women) performed a maximal continuous graded exercise test for the determination of maximal oxygen consumption (VO2max), ventilatory threshold (VT), peak treadmill velocity (PTV) and HRR, as well as a test to measure the autonomic regulation of heart rate during supine rest, using HRV analysis. Once both tests were completed, subjects were matched for VO2max and assigned to the low endurance or the high endurance group, depending on the %PTV at which VT occurred (81.9 +/- 2.9 and 88.3 +/- 3.1%PTV for both groups, respectively; P < 0.0001). Contrary to our hypotheses, neither HRV nor HRR parameters were different between groups or associated with aerobic endurance. VO2max (59.0+/-7.3 ml min(-1) kg(-1)) was inversely correlated with ln SDNN (r = -0.44, P < 0.05), ln HF (r = -0.52, P < 0.05), ln LF + HF (r = -0.53, P < 0.05). These results suggest that aerobic endurance is not associated with cardiovascular autonomic control, as measured by HRV and HRR.

V·O2 Kinetics during Supramaximal Exercise: Relationship with Oxygen Deficit and 800-m Running Performance

The aim of this study was to compare .VO2 kinetics of highly- versus recreationally-trained subjects during a constant velocity test of supramaximal intensity. Eighteen trained male subjects were recruited to one of two groups: highly trained (HT, n = 8, .VO(2max) = 70.1 +/- 6.5 ml . min (-1) . kg (-1)) and recreationally trained (RT, n = 10, .VO(2max) = 63.2 +/- 6.4 ml . min (-1) . kg (-1)). All subjects performed an incremental test to exhaustion for the determination of .VO(2max) and peak treadmill velocity (PTV), two constant velocity tests at 110 % of PTV to determine .VO2 kinetics and oxygen deficit (O(2)def), and a 800-m time trial to determine running performance (mean velocity over the distance, V (800 m)). We found significant differences between HT and RT for the on-transient of the .VO2 response (tau, 24.7 +/- 3.3 and 30.9 +/- 7.0 s, respectively), the amplitude of the .VO2 response (60.0 +/- 5.0 and 53.5 +/- 5.7 ml . min (-1) . kg (-1), respectively) and V (800 m) (6.27 +/- 2.1 and 5.45 +/- 0.38 m . s (-1), respectively). O(2)def (24.6 +/- 2.7 and 27.7 +/- 7.8 ml . kg (-1), respectively) and the gain of the .VO2 response (193 +/- 14 and 194 +/- 13 ml . kg (-1) . m (-1), respectively) were similar between groups. tau was associated with O(2)def (r = 0.90, p < 0.05), but not with V (800 m) (r = 0.30, p > 0.05). It was concluded that HT subjects exhibited faster on-kinetics and higher amplitude than their RT counterparts. The higher amplitude was not thought to reflect any difference in underlying physiological mechanisms. The faster tau, whose exact mechanisms remain to be elucidated, may have practical implications for coaches.

Aerobic fitness and field test performance in elite Spanish soccer referees of different ages

The major aim of this study was to examine the physical fitness of elite Spanish soccer referees in relation to their age. A secondary aim was to assess the population criterion validity of the 12 min running test (12 MRT) against aerobic-fitness laboratory tests. Participants were 45 soccer referees (age 35.5+/-4.4 years, height 178.3+/-5.0 cm, body mass 75.1+/-6.6 kg, body fat 11.3+/-2.15%, VO2(max), 54.9+/-3.9 ml kg(-1) min(-1)) who were enrolled in the Referees Technical Committee of the Royal Spanish Soccer Federation. They were divided into three age groups: young (Y, 27-32 years, n=15), average (A, 33-38 years, n=17) and old (O, 39-45 years, n=13). No age-related effects were observed for VO2(max), 12 MRT or 200 m sprint performance in either the pooled or grouped data. However, age-related performance decrements were observed for 50 m sprint performance and the ventilatory threshold (VT) running speed. Twelve MRT performance was moderately related to VO2(max), (r=0.46, P=0.002), VT (km h(-1)) (r=0.49, P<0.001), and peak treadmill velocity (PTV) (r=0.60, P<0.001). The results showed that older elite-level referees may be able to limit the expected age-related performance decrements in both aerobic and anaerobic performance usually reported for sedentary people. Additionally, these results show that older referees are able to reach physical fitness levels that have been suggested to be appropriate for coping with match demands.

Velocity at V?O2 max and peak treadmill velocity are not influenced within or across the phases of the menstrual cycle

Velocity at VO(2 max) (vV(.)O(2 max)) and peak treadmill velocity (PTV) are variables highly predictive of endurance performance. However, how these variables are affected by the menstrual cycle is unknown. The aim of this study was to assess the effect of the menstrual cycle on vV(.)O(2 max) and PTV. Ten, female runners were studied across three menstrual cycles. Training, menstrual history and mood states were assessed for 2 months, with daily salivary samples taken to detect menstrual phases. During the third menstrual cycle, participants completed a maximal test to determine V(.)O(2 max), vV(.)O(2 max) and PTV in the early follicular phase, late follicular phase, early luteal phase, late luteal phase and menses. Progesterone increased at the onset of the luteal phase [mean (SEM); 490 (73.6) pmol l(-1)] compared to the follicular phase [344.6 (59.7) pmol l(-1)). No significant differences in the psychological mood states between the phases of the menstrual cycle were found (P>0.05). No significant differences in vV(.)O(2 max) (P=0.611), or PTV (P=0.472) were found between the phases of the menstrual cycle. Thus, vV(.)O(2 max) and PTV are not affected by the monthly menstrual cycle in female endurance runners.

Physical and performance-related profile of elite male South African distance runners

Profiling the physical and performance related characteristics of sportsmen and women is an integral component of research within a particular sport. The purpose of this study was firstly to obtain a physiological profile of elite male South African distance runners. Secondly, to verify the correlation between peak treadmill velocity and distance running performance. Thirdly, to determine if a correlation exists between leg strength (quadriceps/hamstrings) and peak treadmill velocity. Anthropometry, isokinetic strength and endurance and maximal oxygen uptake (VO2max) evaluations were performed on male (n=23) distance athletes. The means and standard deviations of the parameters are as follows: Percentage fat 8.0% (±1.3), percentage muscle 46.2% (±2.9), VO2max 70.1ml/kg/min (±5.2), peak RER 1.03 (±0.04), peak heart rate 187bpm (±10.8), peak velocity 20.2km/h (±1.4), peak lactate 8.25mmol.l-1, peak torque (PT) ft-lbs 60°/s right extensors 118.18 (±26.81), PT ft-lbs 60°/s left extensors 110.27 (±25.34), PT ft-lbs 60°/s right flexors 63.05 (±14.43), PT ftl-bs 60°/s left flexors 59.68 (±12.87), flexor/extensor ratio 60°/s right 53.91% (± 9.05), flexor/extensor ratio 60°/s left 53.27% (±11.02). Importantly, a significant (p