Search

Abstract The findings of previous studies investigating the strength of the relationships between the percentages of maximal heart rate (%HRmax), heart rate reserve (%HRR), maximal oxygen uptake (%VO2max), and oxygen uptake reserve (%VO2R) have been equivocal. This inconsistency between studies could largely be due to differ- ences in methodology. The purpose of this study was therefore to determine whether different VO2max test protocols and resting VO2 assessment influence the relationships between the %HRmax, %HRR, %VO2max, and %VO2R. Thirty-three young men performed maximal treadmill protocols (ramp, Bruce) to assess HRmax and VO2max. Resting VO2 was assessed as follows: a) resting VO2standard, using strict criteria (24h exercise abstention, alcohol, soft drinks, or caffeine: 8h fasting: 30mm assessment): b) resting VO2sitting and: c) resting VO2standing (both 5 mm before exercise testing). The %HRR was closer to %VO2max than to %VO2R, especially in the ramp protocol (p<0.001). In the Bruce protocol, relationships were closer to the identity line, and there was no significant difference between %HRR and %VO2max, or %VO2R. The VO2max was significantly higher in the ramp protocol compared to the Bruce protocol (p<0.001). In both protocols resting VO2 assessment produced no significant difference in the intercepts and slopes of the %HRR-%VO2R relationships obtained from individual regression models. The %VO2R calculated using resting VO2Standard was closer to %HRR compared to VO2sitting and VO2standing. The premise that %HRR is more strongly related to %VO2R than to %VO2max was not confirmed. Methodological differences should be considered when interpreting previous studies investigating %HRmax, %HRR, %VO2max, and %VO2R relationships. [ABSTRACT FROM AUTHOR]

This study intended to investigate walking economy (WE) in response to different treadmill speeds and grades in adults with Down syndrome (DS) and in non-disabled controls. Eighteen participants (14 males; 4 females) with DS (33.6�7.6 years) and 16 non-disabled (12 males, 4 females) controls (33.3�8.0 years) performed submaximal (2.5 km . h−1 and 4 km . h−1 at 0% grade; 4 km . h−1 at 2.5% and 5% grade, for 5 min each) and maximal treadmill tests with metabolic and heart rate measurements. Oxygen uptake (VO2) was not different between groups at rest or during the slowest treadmill speed. However, at faster speeds and increased grades, adults with DS presented lower WE than controls (p<0.0001). Subsequent analyses revealed that, despite showing higher delta VO2 response to the selected speed increments (p<0.0001), individuals with DS produced similar VO2 increase as controls to grade variations. Therefore, adults with DS exhibit lower WE than non-disabled controls at a speed faster than their preferred walking speed. Additionally, in comparison to controls, individuals with DS show a greater change in energy expenditure with a change in walking speed. In conclusion, lower WE in individuals with DS is mainly related to their inability to adapt efficiently to positive variations in walking speed. [ABSTRACT FROM AUTHOR]

This study examined the effect of ingesting a high or low glycemic index (GI) meal during a short-term recovery period on endurance running capacity. On two occasions, seven men (age 30.0±2.6yr, body mass 60.7±1.4kg, VO2max 62.1 ±2.2 ml∙kg-1∙min-1) ran at 70% VO2max on a level treadmill for 90mm (R1), followed by a 4h recovery (REC) and a further exhaustive run at the same speed (R2). Twenty minutes after RI, each subject consumed an isoenergetic meal containing either high GI (HGI, Gl=77) or low GI (LGI, Gl=37) carbohydrate providing 1.5g CHO kg-1 BM. During REC, subjects also ingested a prescribed volume of water equal to 150% of their BM loss during R1. The duration of R2 in the HGI trial was 15% longer than in the LGI trial (HGI: 86.6±10.7mm vs. LGI: 75.2±8.1 mm, p<0.05). The subjects also achieved complete rehydration after REC on both occasions. In conclusion, the consumption of a HGI meal during a 4 h recovery improved endurance capacity in a subsequent run: however, the precise mechanism(s) by which this takes place is yet to be clarified. [ABSTRACT FROM AUTHOR]

We investigated the association between cardiorespiratory fitness (CRF) and carotid atherosclerosis in 9871 Korean men aged 40-81 years. We measured carotid intima-media thickness by using B-mode ultrasonography, and cardiorespiratory fitness was measured by a maximal treadmill exercise test using the Bruce protocol. Carotid atherosclerosis was defined as an intimamedia wall thickness greater than 1.2 mm or stenosis >25% of carotid arteries, while CRF was classified as low fit (<20%), moderately fit (20-<60%), or high fit (⩾60%) categories based on age-specific VO2peak (mI/kg/mm) percentiles. The presence of carotid atherosclerosis across CRF categories was 11.7% (low fit), 9.6%, and 7.7%, respectively. After adjustment for age, cigarette smoking, body mass index, physical activity, there was an inverse association between CRF and carotid atherosclerosis (p for trend <0.001). The odds ratio of presence of carotid atherosclerosis in the high-fit men versus the low-fit men was 0.67 (95% Cl, 0.55, 0.80). After additional adjustment for high cholesterol, hypertension, and diabetes mellitus, the results remain unchanged and the odds ratios across CRF levels were (95% Cl): 1.00 (low fit, referent), 0.85 (0.71, 1.01), 0.71 (0.59, 0.85) (p for trend <0.001), respectively. High levels of cardiorespiratory fitness were associated with a lower risk of having carotid atherosclerosis in middleaged and elderly men. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to identify physiological predictors of maximum treadmill walking performance (MWD) in patients with intermittent claudication. Forty-five claudicants performed a graded treadmill test to determine MWD, peak oxygen uptake, and gas exchange threshold. Calf muscle oxygenation (StO2) at 1 mm and time to minimum StO2 were also measured using near-infrared spectroscopy. On other occasions, peak calf blood flow, resting ankle-brachial index, and pulmonary oxygen uptake kinetics during steady-state walking were assessed. A forward stepwise multiple regression analysis was performed to determine predictors of MWD. A regression model comprising time to minimum StO2, peak oxygen uptake, and StO2 at 1 min explained 64% of the variation in MWD. The results suggest that cardiopulmonary fitness and the ability to match oxygen delivery to metabolic demand are important determinants of walking performance in claudicants, and that certain near-infrared spectroscopy variables might be useful in studies that evaluate the mechanisms of clinical improvement with different treatment interventions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of music tempi on music preference, intrinsic motivation, and flow during long-duration exercise (~26 min). Subjects (n = 29) selected the music of a single artist then walked at 70% of maximum heart rate reserve (maxHRR) on a treadmill under three experimental conditions (medium tempi, fast tempi, and mixed tempi) and a no-music control. A music preference item, the Intrinsic Motivation Inventory, and Flow State Scale-2 were completed after each trial. Data were analyzed using a mixed-model (Gender × Condition) ANOVA and MANOVA. The Gender × Condition interaction was nonsignificant in both analyses (p > 0.05). Contrary to expectations, higher preference scores were recorded for medium tempi than for mixed tempi (means: 7.8 ± 1.3 vs. 7.1 ± 1.1). The medium tempi music also yielded the highest levels of intrinsic motivation (p < 0.001). Pairwise comparisons showed that interest-enjoyment was higher for medium tempi when compared to mixed tempi, 95% CI = 1.80-8.48, p = 0.001, and that each of the music preference experimental conditions yielded higher scores than the no-music control. Also, pressure-tension was lower for medium tempi compared to fast tempi, 95% Cl = -3.44-0.19, p = 0.022, and for both medium and mixed tempi compared to control (95% Cl = -5.33-2.89, p = 0.000; 95% Cl = -4.24-0.64, p =0.004). A main effect was found for global flow (p = 0.000) with the highest mean score evident in the medium tempi condition (14.6± 1.5). Follow-up comparisons indicated that the medium tempi condition yielded higher flow scores than the control, 95% CI = 1.25-3.60, p = 0.000, as did fast tempi, 95% Cl = 0.89-3.14, p = 0.000, and mixed tempi, 95% CI =1.36-3.76, p = 0.000. It was concluded that a medium tempi music program was the most appropriate for an exercise intensity of 70% maxHRR. [ABSTRACT FROM AUTHOR]

The present study examined the use of the maximal lactate steady state (MLSS) as an exercise training stimulus in moderately trained runners. Fourteen healthy individuals (12 male, 2 female; age 25 ± 6 years, height 1.76 ± 0.05 m, body mass 76 ± 8 kg mean ± SD) took part in the study. Following determination of the lactate threshold (LT), VO2max, running velocity at MLSS (vMLSS) and a control period of 4 weeks, participants were pair matched and split into two cohorts performing either continuous (CONT: 2 sessions/ week at vMLSS) or intermittent treadmill running (INT: 2 sessions/week, 3-mm repetitions 0.5 km·h-1 above and below vMLSS). vMLSS increased in CONT by 8% from 12.3 ± 1.5 to 13.4 ± 1.6 km · h-1 (p <0.05) and in INT by 5% from 12.2± 1.9 km · h-1 to 12.9 ± 1.9 km · h-1 (p<0.05). Running speed at the LI increased by 7% in the CONT group (p <0.05) and by 9% in the INT group (p<0.05). VO2max increased by 10% in the CONT group (p <0.05) and by 6% in INT (p <0.05). Two sessions per week at vMLSS are capable of eliciting improvements in the physiological responses at LT, MLSS, and VO2max in moderately trained runners. [ABSTRACT FROM AUTHOR]

We investigated the oxygen uptake response (VO2) to a 1500-m test conducted using a competition race strategy. On an outdoor track, eleven middle-distance runners performed a test to determine VO2max, velocity associated with VO2max (v-VO2max) and a supramaximal 1500-m running test (each test at least two days apart). VO2max response was measured with the use of a miniaturised telemetric gas exchange system (Cosmed, K4, Roma, Italy). The 1500-m running test was performed at a mean velocity of 107. 6+2% v-VO2max. The maximal value of oxygen uptake recorded during the 1500-m test (VO2peak) was reached by subjects at 75.9+7.5 s (mean + SD) (i.e., 459±59 m). The time to reach VO2max (TVO2peak) and the start velocity (200- to 400-m after the onset of the 1500 m) expressed in % v-VO2max were negatively and significantly correlated (p < 0.05), but our results indicate that a fast start does not necessarily induce a good performance. These results suggest that VO2max is reached by all the subjects at the onset of a simulated 1500-m running event and are therefore in contrast with previous results obtained during treadmill running. [ABSTRACT FROM AUTHOR]

This study sought to determine the influence of 16 months of progressive aerobic exercise on excess postexercise oxygen consumption (EPOC) and the extent EPOC contributed to weight management. Twenty-five overweight/obese women and 16 overweight/obese men participated in a 16-month exercise program (moderate-intensity treadmill walking) that progressed across the first 26 weeks to 5 days·wk-1, 45 min·session-1, and 75% HRR. Three-hour EPOC was measured at baseline, 9 months, and 16 months by indirect calorimetry in response to an exercise session (treadmill walking), in which energy expenditure (EE) was estimated from the participant's previous 10 exercise sessions. For women, EPOC was 7.5 ± 4.9, 9.6 ± 7.6, and 6.5 ± 6.5 L at baseline, 9 months, and 16 months, respectively (p > 0.05). For men, EPOC increased from baseline (11.8 ± 6.8 L) to 9 months (13.5±8.6 L) (p<0.05) with no further increase at 16 months (13.5 ± 11.0 L). Change in EPOC was correlated with change in EE at 9 months (r= 0.65; p <0.05) and 16 months (r=0.58; p<0.05) for men but not women. Progressive long-term exercise significantly influenced EPOC in overweight/obese men but not women. Change in volume of exercise likely explained the increase in energy expenditure during EPOC in men. EPOC contributed modestly to EE compared to the exercise itself. [ABSTRACT FROM AUTHOR]

Effects of methodological differences on the determination of time at V̇O2max (tV̇o2max) during intermittent treadmill running were investigated. Subjects performed three incremental tests to volitional exhaustion: a continuous protocol with 1-min stages (Cont-1NC[1-min]), and two discontinuous protocols of 2-min (Dis-INCF[2min]) and 3-min (Dis-INC[3min]) stage durations. For each test, V̇O2max and the running velocity associated with V̇O2max (vV̇O2max) were determined. On a fourth visit, subjects performed an intermittent test with 30-s work and relief intervals run at 105% and 60%, respectively, of the VV̇O2max determined during Cont-INC(1-min). The tV̇O2max during the intermittent test was determined using three different criteria: V̇O2 data points ≥ 100% V̇O2max determined in Cont-INC(1-min) (tV̇2max[100%]), ≥95% V̇O2max (tV̇O2max[95%]) and ≥V̇O2max minus 2.1 ml·kg-1·min-1 (tV̇o2max[-2.1]). The V̇O2max means (SD) for Cont-INC(1-min), DIS-INC(2-min) and Dis-INC were 4093 (538), 4096 (516), and 3980(488) mL·min-1, respectively. The tV̇O2max means (SD) were: tV̇2max (100%) 163 (227)s, tV̇O2max(95%) 418 (439)s, and tV̇O2max(-2.1) 358 (395)s. All differences in tV̇O2max were significantly different (p <0.05). Differences in tV̇O2max due to using V̇O2max values derived from using different VO2 time-averages were significantly different (p <0.05). Methodological differences or 15s [5,12], a difference that may also affect tV̇O2max determination. Methodological inconsistencies that affect the initial determination of V̇O2max are also likely to affect tV̇O2max during intermittent running. Studies investigating tV̇O2max have sometimes used incremental tests for V̇O2max determination that have lasted more than 20 min [5,12]. Prolonged incremental tests have been found to result in lower V̇O2max values than tests lasting 8-12 min [1, 9]. Different V̇O2 averaging techniques have also been used for V̇O2max determination. Stationary retrograde time-averages of 15-s [12] and 30 s (27], as well as 2-point [5] and 4-point [14] rolling 15-s time-averages, have been reported. Longer time-averaging intervals have been associated with lower V̇O2max values [20]. Incremental test protocols or V̇O2 data manipulation methods that tend to lower V̇O2max values are likely to artificially increase tV̇O2max. We hypothesised that tV̇O2max determined using different methodologies would result in significantly different tV̇2max during an intermittent treadmill running test. This study extends the work of Dupont et al. (13], who investigated the effect of methodological differences on tV̇O2max during a single constant velocity run to exhaustion.… [ABSTRACT FROM AUTHOR]

Erythropoietin gene expression is stimulated by hypoxia-inducible factor 1 and inhibited by GA- TA. Thus, drugs that attenuate the action of GATA and/or potentiate the action of HIF-1 may increase Epo production and hemoglobin concentration. The effects of such drugs on endurance performance and the potential mechanisms by which they may exert effects are unclear. In Hep3B cells, we showed that K-11706 inhibits GATA binding activity, but enhances HIF-1 binding activity. However, the expression levels of GATA and HIF-1 protein were not changed by the addition of K-11706. We investigated the effects of K-11706 on Epo and Hb concentrations, hematocrit and endurance performance of mice (total number of mice =40). K-11706 was dissolved in polyethylene glycol and administered via oral tube feeding to mice for either five or eight days. Endurance performance was assessed using a treadmill. Muscle fibers from the quadriceps muscles of mice were stained with ATPase. Administration of 3 mg/kg K-11706 for five or eight days significantly increased erythropoietin concentrations, hemoglobin concentrations, hematocrit and endurance performance, but the diameters of cross-sections and ratios of type I, IIA and IIB muscle fibers were not affected. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare VO2 kinetics of highly- versus recreationally-trained subjects during a constant velocity test of supramaxirnal intensity. Eighteen trained male subjects were recruited to one of two groups: highly trained (HT, n = 8, VO2max = 70.1 ± 6.5 ml · min-1 · kg-1) and recreationally trained (RT, n = 10, VO2max = 63.2 ± 6.4 ml · min-1 · kg-1). All subjects performed an incremental test to exhaustion for the determination of VO2max and peak treadmill velocity (PTV), two constant velocity tests at 110% of PTV to determine VO2 kinetics and oxygen deficit (O2def), and a 800-m time trial to determine running performance (mean velocity over the distance, V800m). We found significant differences between HT and RT for the on-transient of the VO2max response (̄, 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 mI · min-1· kg-1, respectively) and V800m (6.27 ± 2.1 and 5.45 ± 0.38 m s-1, respectively). O2def (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. t was associated with O2def (r = 0.90, p < 0.05), but not with V800m (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 ̄, whose exact mechanisms remain to be elucidated, may have practical implications for coaches. [ABSTRACT FROM AUTHOR]

Lower body negative pressure (LBNP) treadmill exercise can generate a hypergravity load on the lower body that may improve athlete performance by mechanical and cardiovascular adaptations. This study compared the cardiovascular responses, subjective exertion and discomfort levels produced by LBNP exercise with those generated by a weighted vest (WV). We hypothesized that LBNP exercise is more comfortable than WV exercise at comparable levels of exercise. Nine subjects exercised on a treadmill at nine conditions, at 5.5 mph for 15 minutes, in which they ran in random order to avoid confounding effects: 100%, 110%, 120%, 130%, and 140% body weight (BW), the latter four conditions were achieved by either LBNP chamber or WV. Heart rate (HR) and oxygen consumption (VO2) were monitored continuously using ECG and open circuit spirometry. At the end of each test, subjects were asked to give discomfort and exertion scores using a ten-point visual analog scale (10 = maximal discomfort and exertion). For both HR and VO2, no significant differences were observed between LBNP and WV. Subjects reported significantly higher discomfort levels when exercising with the WV than with the LBNP at 120% BW(5.1 ± 0.55 vs. 3.1 ± 0.64; p < 0.05), 130% BW (6.2 ± 0.42 vs. 2.3 ± 0.44; p < 0.01) and 140% BW (6.9 ± 0.27 vs. 4.7 ± 0.60; p < 0.01), while maintaining similar exertions at all conditions. Based on these results, LBNP exercise is more comfortable than standard WV exercise, while maintaining similar exertion, HR and VO2 values. [ABSTRACT FROM AUTHOR]

The study aim was to consider the use ofa motorised treadmill as a cycling ergometry system by assessing predicted and recorded power output values during treadmill cycling. Fourteen male cyclists completed repeated cycling trials on a motorised treadmill whilst riding their own bicycle fitted with a mobile ergometer. The speed, gradient and loading via an external pulley system were recorded during 20-s constant speed trials and used to estimate power output with an assumption about the contribution of rolling resistance. These values were then compared with mobile ergometer measurements. To assess the reliability of measured power output values, four repeated trials were conducted on each cyclist. During level cycling, the recorded power output was 257.2±99.3W compared to the predicted power output of 258.2 ± 99.9W (p > 0.05). For graded cycling, there was no significant difference between measured and predicted power output, 268.8 ± 109.8W vs. 270.1 ± 111.7W, p > 0.05, SEE 1.2%. The coefficient of variation for mobile ergometer power output measurements during repeated trials ranged from 1.5% (95% CI 1.2-2.0%) to 1.8% (95% CI 1.5-2.4%). These results indicate that treadmill cycling can be used as an ergometry system to assess power output in cyclists with acceptable accuracy. [ABSTRACT FROM AUTHOR]

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 (VO2max = 66.54 ± 7.29 ml·min-1·kg-1) performed an incremental test to exhaustion for the determination of VO2max and peak treadmill velocity (PTV), five randomly ordered constant velocity tests at 95, 100, 105, 110, and 120% of Ply to compute ARC and oxygen deficit (O2def, at 110% of PTV), and a 800-m time trial to determine running performance (mean velocity over the distance, V800m) and peak blood lactate concentration ([La-]b, peak). ARC (467 ± 123 m) was positively correlated with O2def (56.35 ± 18.47 ml·kg-1 r = 0.57; p < 0.05), but not with [La-]b, peak (15.08 ± 1.48 mmol·1-1 r = -0.16; p > 0.05). The O2 equivalent of ARC (i.e., the product of ARC by the energy cost of running; 103.74 ± 28.25 mI·kg-1), which is considered as an indirect estimation of O2def, was significantly higher than O2def (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, O2def can be considered as a criterion measure for it. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the reproducibility of time at or above 90% (t90% V̇O2max) and 95% (t95% V̇O2max) maximal oxygen uptake during an intermittent treadmill run to exhaustion. Twenty-two distance runners (age 38.0 ± 7.1 yrs) performed two identical incremental and two identical intermittent tests on four separate days. Respiratory exchange was measured continuously throughout each test by an automated open-circuit gas analysis system. The incremental test consisted of increases in treadmill speed every minute until volitional exhaustion. The highest averaged 30-s oxygen uptake (V̇O2) value was defined as V̇O2max and the minimum speed that elicited V̇O2max was defined as vV̇O2max. The intermittent test consisted of 30-s work intervals ran at 105% vV̇O2max interspersed by 30-s relief intervals ran at 60% vV̇O2max and was continued until volitional exhaustion. The time that V̇O2 was at or above 90% and 95% of the mean maximum values elicited during the two previous incremental tests was determined for the intermittent tests. The mean t95% V̇O2max was 232 (SD 174) s and 244 (SD 195) sand the mean t90% V̇O2max was 480 (SD 220)s and 488 (SD 252)s, for trial 1 and trial 2, respectively. Reproducibility statistics for t95% V̇O2max and t90% V̇O2max, respectively, were: 95% limits of agreement 12 ± 227 sand 8 ± 328 s; coefficient of variation 34.5% and 24.5%; and intraclass correlation coefficient 0.80 and 0.75. Statistical power analysis indicated that this level of reproducibility would allow mean differences of 15–20% between intermittent training protocols to attain statistical significance in future experimental research, with sample sizes probably within the resources of most researchers. [ABSTRACT FROM AUTHOR]

Although repeated sprint tests are relatively common, there have been few investigations of repeated sprint exercise using non- motorised treadmill ergometry. The purpose of this study was to determine the reliability of a repeated sprint procedure using this apparatus. Ten healthy, active males, performed three repeated sprint tests (six repetitions of 6 s sprints with 30 s recovery) on three separate occasions. Performance as determined by maximal speed, average force production, and fatigue were compared across the three trials. Maximal speed and average force were not significantly different between visits (p

The objective of this study was to analyze, in triathletes, the possible influence of the exercise mode (running x cycling) on time to exhaustion (IrE) and oxygen uptake (`~O2) response during exercise performed at the intensity associated with the achievement of maximal oxygen uptake (lVO2max). Eleven male triathietes (21.8 ± 3.8 yr) performed the following tests on different days on a motorized treadmill and on a cycle ergometer: 1) incremental tests in order to determine VO2max and lVO2~ax and, 2) constant work rate tests to exhaustion at lVO2max to determine TTE and to describe V02 response (time to achieve V02mJx - TAVO2max, and time maintained at "°2max - TMVO2max). No differences were found in VO2max, 1TE and TMVO2max obtained on the treadmill tests (63.7 ±4.7 ml .kg1 .min1 324.6 ± 109.1 5; 178.9 ± 93.6 s) and cycle ergometer tests (61.4 ± 4.5 ml. kg-1 . mm-1 390.4 ± 114.4s: 213.5 ± 102.4 s). However, TA'fO2max was influenced by exercise mode (145.7 ±25.3 vs. 176.8±20.1 s; in treadmill and cycle ergometer, respectively: p = 0.006). It is concluded that ex- ercise modality affects the TA'/O2maX, without influencing TI'E and TMVO2max during exercise at lVO2max in triathletes. [ABSTRACT FROM AUTHOR]

To evaluate the effect of temperature on running economy (RE) and stride parameters in 10 trained male runners (~O2peak 60.8 ± 6.8 ml kg~ . min1), we used water immersion as a passive temperature manipulation to contrast localised pre-heating, pre- cooling, and thermoneutral interventions prior to running. Runners completed three 10-mm treadmill runs at 70% ~O2peak following 40 mm of randomised leg immersion in water at 21.0°C (cold), 34.6°C (thermoneutral), or 41.8°C (hot). Treadmill runs were separated by 7 days. External respiratory gas exchange was measured for 30s before and throughout the exercise and stride parameters were determined from video analysis in the sagittal plane. RE was not affected by prior heating or cooling with no difference in oxygen cost or energy expenditure between the temperature interventions (average V02 3rd - 10th mm of exercise: C, 41.6±3.4ml~kg1~min1 TN, 41.6±3.0; H, 41.8±3.5; p=0.94). Exercise heart rate was affected by temperature (H > TN> C: p <0.001). During minutes 3-5 of running the respiratory-exchange and minute ventilation/oxygen consumption ratios were greater in cold compared with thermoneutral (p <0.05). Averaged over the full 10 mm of exercise, stride length was shorter and stride frequency higher for the C trial compared to TN and H (p <0.01). Leg temperature manipulation did not influence running economy despite changes in stride parameters that might indicate restricted muscle-tendon elasticity after pre-cooling. Larger changes in stride mechanics than those produced by the current temperature intervention are required to influence running economy. [ABSTRACT FROM AUTHOR]

Exercise shares many similarities with the acute phase response of inflammatory diseases. Recently, elevated serum levels of the novel pro-inflammatory molecules of the SiDO protein family, S100A8 and S100A9, have been associated with various inflammatory diseases. The present study was conducted to assess their potential roles as inflammatory markers in monitoring the exercise-induced immune response. Seventeen male subjects of different training status performed a marathon run. Furthermore 13 subjects (10 male, 3 female) performed three different tread- mill tests: strenuous (STE), moderate (MTE), and downhill (DTE). S100A8/A9 complexes were measured by ELISA, while white blood cell count (WBC) and C-reactive protein (CRP) were used as markers of the inflammatory response. Serum creatine kinase (CK) concentration was determined as a marker for muscle dam- age. After marathon S100A8/A9 increased dramatically during the early post-exercise period and returned to resting levels one day after the run. A similar pattern was found for WBC, while CM and CRP reached their maximum on the day after the run. More- over, SIOOA8/A9 release was higher in the subgroup of well- trained athletes. The kinetic of the SIOOA8/A9 release after the treadmill tests depended on exercise intensity and was prolonged after eccentric exercise. In summary, the present results indicate that the novel pro-inflammatory molecules S100A8/A9 are very early and sensitive markers of the exercise-induced inflammatory response. Further investigations are necessary to evaluate the applicability of S100A8/A9 for monitoring the training process and to elucidate the dependence on training status. [ABSTRACT FROM AUTHOR]

The oxygen uptake (V·O 2) attained during a constant speed 800-m pace trial on a treadmill is less than the maximal V·O 2 (V·O 2max) in male middle-distance runners with a high V·O 2max (i.e., > 65 ml · kg -1 · min -1). We therefore investigated whether the V·O 2 attained was influenced by the pacing strategy adopted. Eight male middle-distance runners (age 25.8 ± 3.3 years; height 1.78 ± 0.10 m; mass 67.8 ± 4.7 kg) with a personal best 800-m time of 112.0 ± 3.3 s volunteered to participate. Subjects undertook a speed ramped progressive test to determine V·O 2max and three 800-m pace runs to exhaustion all in a randomised order. The three 800-m pace runs included constant speed, acceleration, and race simulation runs. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest V·O 2 during the progressive test (i.e., V·O 2max) and the highest V·O 2 during the 800-m pace runs (i.e., V·O 2peak) were compared. For the eight runners, V·O 2max was 67.2 ± 4.3 ml · kg -1 · min -1. V·O 2peak was 60.1 ± 5.1 ml · kg -1 · min -1, 61.1 ± 5.2 ml · kg -1 · min -1, and 62.2 ± 4.9 ml · kg -1 · min -1, yielding values of 89.3 ± 2.4 %, 90.8 ± 2.8 %, and 92.5 ± 3.1 % V·O 2max for the constant speed, acceleration and race simulation runs, respectively. Across runs, repeated measures ANOVA revealed a significant effect (p = 0.048). Trend analysis identified a significant linear trend (p = 0.025) with the % V·O 2max attained being higher for the acceleration run than the constant speed run, and higher still for the race simulation run. These results demonstrate that in middle-distance runners a) pacing strategy influences the V·O 2 attained, with a race simulation run elevating the V·O 2 attained compared with other pacing strategies, and b) regardless of pacing strategy the V·O 2 attained in an 800-m pace run on a treadmill is less than V·O 2max. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of age and recovery duration on performance during multiple treadmill sprints. Twelve boys (11.7 ± 0.5 y) and thirteen men (22.1 ± 2.9 y) performed ten consecutive 10-s sprints on a non-motorised treadmill separated by 15-s (R15) and 180-s (R180) passive recovery intervals. Mean power output (MPO), mean force output (MFO), running velocity, step length, and step rate were calculated for each sprint. Capillary blood samples were drawn from the fingertip at rest and 3 min after the tenth sprint to measure the lactate accumulation (Delta [La]). With R15, all mechanical parameters decreased significantly less in the boys than in the men over the ten sprints (MPO: - 28.9 vs. - 47.0 %, MFO: - 13.1 vs. - 25.6 %, running velocity: - 18.8 vs. - 29.4 %, p < 0.001, respectively). With R180, all mechanical values remained unchanged in the boys. In the men, MPO and MFO significantly decreased over the ten sprints (- 7.8 % and - 4.6 %, p < 0.05, respectively). The running velocity, however, did not decrease because the decrease in step rate (p < 0.001) was compensated by an increase in step length. For either recovery interval, Delta [La] values were higher in the men compared to the boys (R15: 12.7 vs. 7.7 mmol · L -1, p < 0.001, R180: 10.7 vs. 7.7 mmol · L -1, p < 0.05). To conclude, the boys maintained more easily their running performance than the men during repeated treadmill sprints with R15. Three-minute recovery periods were sufficient in the boys to repeat short running sprints without substantial fatigue. Despite the decrease in power and force outputs with R180, the young men were able to maintain their running velocity during the test. [ABSTRACT FROM AUTHOR]

The objective of our study was to evaluate the effect of short-term Intensive exercise on the susceptibility of serum lipids to ex-vivo peroxidation. We assessed the association between aerobic capacity, serum composition, and serum lipid oxidizability as well as the association between aerobic capacity and the effect of short-term maximal exercise on the kinetics of ex-vivo copper-induced peroxidation of serum lipids. The study involved 30 healthy male volunteers (age 22-39 years, BMI 19.4-29.8). Following 12-hr fasting, blood was withdrawn for determination of blood lipids, LDL, HDL, and TG, and Vitamin E, and for oxidizability assay of the serum lipids. Subsequently, each volunteer underwent an incremental all-out cardiopulmonary exercise stress test (CPET), performed on a motor-driven treadmill (Quinton Q65, USA). The test protocol was a modified Balke protocol. The results of this test were expressed in terms of mass-dependent maximal oxygen uptake (O2max ml · kg-1· min-1) and of ventilatory anaerobic threshold (VAT, ml · kg-1 min-1). Immediately after exercise, blood was re-drawn for the determination of serum Vitamin E and for ex-vivo oxidizibility assay, expressed in terms of maximal absorption of oxidation products (ODmax, absorbance units), maximal rate of their production (Vmax, OD min-1) and the time at which the rate was maximal (tmax, min). Maximal graded exercise had no significant effect on the susceptibility of serum lipids to peroxidation as measured by ODmax (p = 0.38 at 245 nm, and 0.27 at 268 nm), Vmax (p = 0.34 at 245 nm, and 0.49 at 268 nm) and tmax (p=0.17 at 245 nm, and 0.07 at 268 nm). Also no effect was found on the concentration of serum Vitamin E (p=0.39). Aerobic capacity was not associated either with the susceptibility of serum lipids to ex-vivo peroxidation or with serum Vitamin E concentration. The present findings indicate that a short graded maximal exercise, lasting 8-12 min, is not sufficient to increase the susceptibility of the serum lipids to peroxidation. Thus it may be assumed that the antioxidant capacity of most healthy subjects provides proper protection from a short exhaustive exercise challenge. Also, aerobic capacity in the range represented by our subjects does not seem to influence the susceptibility of serum lipids to peroxidation. [ABSTRACT FROM AUTHOR]

The determination of anaerobic capacity (AC) using treadmill ergometry is problematic from a methodological, as well as a technical standpoint. In this study, a procedure from Monod and Scherrer was modified to examine whether realistic magnitudes of AC could be determined using three subject groups with different levels of anaerobic training. The subject groups consisted of 10 untrained (UT), 10 aerobic-trained runners (AeT), and 10 anaerobic-trained 400-meter sprinters (AnT). In two separate test series, first the V·O 2max was determined and second the so-called individual anaerobic threshold (IAT) was used to determine the aerobic power for all subjects. Then all subjects completed a series of sprints with increasing speeds above the V·O 2max, from which the work output from each test was calculated. Through linear regression, the point of intersection of the regression line with the y-axis was defined as global AC. The results show typically higher V·O 2max and IAT for AeT (62.2 ml · kg -1 · min -1, 14.7 km · h -1) compared to UT (53.2 ml · kg -1 · min -1; 11.2 km · h -1) and AnT (56.7 ml · kg -1 · min -1; 11.8 km · h -1). AC was significantly higher in AnT (4.1 ± 0.58 kJ) compared to AeT (1.8 ± 0.65 kJ) and UT (3.2 ± 0.68 kJ). The determined absolute values of AC are considerably lower than of comparable examinations using bicycle ergometry. One reason for such an underestimation of AC could be that the horizontal work done during exercise on a treadmill was not taken into enough consideration. Another explanation is that the magnitude of the calculated AC values shows a dependency on the duration of each sprint test. In addition, the critical velocity for all subjects was found to be higher than for IAT, which consequently leads to an underestimation of AC. Moreover, the absolute level of the AC values appears to depend on the endurance of the comparison groups. It can then be concluded that the applied procedure allows for a differentiation amongst a variously trained collective, but does not allow a correct absolute determination of the AC. [ABSTRACT FROM AUTHOR]

This study investigated the effect of a backward training program on the physical and fitness condition of young women. Twenty-six healthy female university students (aged 18-23 years) took part in three different baseline tests: body composition, a sub- maximal treadmill test, and a 20-m shuttle run test. Subjects were divided into a training group (n= 13) and a control group (n= 13). The training group completed a six-week backward run/walk training program. The control group was restricted to their daily activities similar to the four weeks prior to the Onset of the baseline tests. The training group showed a significant (p=0.01) decrease in O2 consumption during both submaximal forward and backward exercise on the treadmill (32% decrease during backward and 30% decrease during forward exercise). A significant (p = 0.01) decrease in percentage body fat (2.4%), a 19.7% decrease in the sum of skinfolds (p = 0.001) and significantly (p = 0.013) improved predicted V̇O2max values from the forward 20-m shuttle run test (5.2%) were also found in the case of the training group. The findings suggest that backward walk/run training improves cardiorespiratory fitness for both forward and backward exercise and causes significant changes in body composition in young women. [ABSTRACT FROM AUTHOR]