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1.
In this study, we examined the consequences of a global alteration in running technique on running kinematics and running economy in triathletes. Sixteen sub-elite triathletes were pre and post tested for running economy and running kinematics at 215 and 250?m?·?min?1. The members of the treatment group (n = 8) were exposed to 12 weeks of instruction in the “pose method” of running, while the members of the control group (n = 8) maintained their usual running technique. After the treatment period, the experimental group demonstrated a significant decrease in mean stride length (from 137.25?±?7.63?cm to 129.19?±?7.43?cm; P <?0.05), a post-treatment difference in vertical oscillation compared with the control group (6.92?±?1.00 vs. 8.44?±?1.00?cm; P <?0.05) and a mean increase in submaximal absolute oxygen cost (from 3.28?±?0.36?l?·?min?1 to 3.53?±?0.43?l?·?min?1; P <?0.01). The control group exhibited no significant changes in either running kinematics or oxygen cost. The global change in running mechanics associated with 12 weeks of instruction in the pose method resulted in a decrease in stride length, a reduced vertical oscillation in comparison with the control group and a decrease of running economy in triathletes.  相似文献   

2.
Abstract

Sixteen men were studied during 6-min bouts of motorized treadmill running at 230 m · min–1 and 0% and 4% grade to compare [Vdot]O2 while using freely chosen stride lengths (CSL) and stride lengths approximately 8% shorter (SSL) and longer (LSL) than CSL. The study also attempted to determine whether stride length variations of these proportions altered [Vdot]O2 differently at the two grades. CSL were greater (p<.05) at 0% than 4% with mean values of 133.5 and 131.5 cm, respectively. Two-way ANOVA (Stride x Grade) with repeated measures yielded significant F values (p<.05) for the main effects of both stride length and grade but not for interaction between the two factors. Mean [Vdot]O2 values were 44.95 and 56.80 ml · kg1 · min–1 at 0% and 4% grade, respectively. The Tukey w procedure was used for comparing the main effect means across both grades for the three stride lengths. These means were 50.94, 49.88, and 51.80 ml · kg1 · min–1 for SSL, CSL, and LSL, respectively, with the CSL mean significantly less than the SSL and LSL means (p<.05). Stride length variations of approximately ±8% did not alter [Vdot]O2 differently at the two grades, and although [Vdot]O2 for SSL and LSL was not different, [Vdot]O2 was significantly (p<.05) increased by 2.1% for SSL and 3.8% for LSL. Not all individual patterns followed the group norm, however, in that three subjects were more economical with short stride lengths and two were more economical with longer strides.  相似文献   

3.
Abstract

The purpose of this study was to assess the relationships among ventilatory threshold T(vent), running economy and distance running performance in a group (N=9) of trained experienced male runners with comparable maximum oxygen uptake ([Vdot]O2 max). Maximal oxygen uptake and submaximal steady state oxygen uptake were measured using open circuit spirometry during treadmill exercise. Ventilatory threshold was determined during graded treadmill exercise using non-invasive techniques, while distance running performance was assessed by the best finish time in two 10-kilometer (km) road races. The subjects averaged 33.8 minutes on the 10km runs, 68.6 ml · kg -1 · min -1 for [Vdot]O2 max, and 48.1 ml · kg -1 · min -1 for steady state [Vdot]O2 running at 243 meters · min -1. The T(vent) (first deviation from linearity of [Vdot]E, [Vdot]CO 2 ) occurred at an oxygen consumption of 41.9 ml · kg -1 · min -1. The relationship between running economy and performance was r = .51 (p>0.15) and the relationship between T(vent) and performance was r = .94 (p < 0.001). Applying stepwise multiple linear regression, the multiple R did not increase significantly with the addition of variables to the T(vent); however, the combination of [Vdot]O2 max, running economy and T(vent) was determined to account for the greatest amount of total variance (89%). These data suggest that among trained and experienced runners with similar [Vdot]O2 max, T(vent) can account for a large portion of the variance in performance during a 10km race.  相似文献   

4.
Previous investigators evaluated running economy (RE) with participants running at the same speed by examining the oxygen consumption (VO2) variance. This study was designed to examine the influence of running speed (RS), exercise intensity, body composition, stride length, and gender on RE. Physical characteristics (mean ± standard deviation) of 22 male and 21 female participants were: age (years) = 27.3 ± 3.5 and 26.0 ± 4.0, and VO2peak (ml · kg-1 · min-1) = 53.9 ± 7.7 and 41.2 ± 5.4, respectively. Participants ran 6 min in duration (0% grade) at an estimated 75% of VO2peak. Multiple regression determined which variables accounted for a significant proportion of RE variance. The following equation defined RE: VO2 (ml · kg-1 · min-1) = (RS2 [m/min] x 0.00048) + (HR% x 0.158) + 7.692. The equation resulted in an R2 of .917 and a standard error of estimate (SEE) of 1.8 ml · kg-1 · min-1. Nonsignificance of regression slope and intercept revealed the RE model could be used for men and women. When cross-validated on a separate sample of physically active participants, the derived model was also highly accurate for evaluating RE (R2 = .901, SEE = 2.3 ml · kg-1 · min-1).  相似文献   

5.
Abstract

The aim of this study was to examine the acute effects of prolonged static stretching (SS) on running economy. Ten male runners ([Vdot]O2peak 60.1 ± 7.3 ml · kg?1 · min?1) performed 10 min of treadmill running at 70%[Vdot]O2peak before and after SS and no stretching interventions. For the stretching intervention, each leg was stretched unilaterally for 40 s with each of eight different exercises and this was repeated three times. Respiratory gas exchange was measured throughout the running exercise with an automated gas analysis system. On a separate day, participants were tested for sit and reach range of motion, isometric strength and countermovement jump height before and after SS. The oxygen uptake, minute ventilation, energy expenditure, respiratory exchange ratio and heart rate responses to running were unaffected by the stretching intervention. This was despite a significant effect of SS on neuromuscular function (sit and reach range of motion, +2.7 ± 0.6 cm; isometric strength, ?5.6% ± 3.4%; countermovement jump height ?5.5% ± 3.4%; all P < 0.05). The results suggest that prolonged SS does not influence running economy despite changes in neuromuscular function.  相似文献   

6.
Abstract

The purpose of the present study was to determine if field-based variables associated with cardiovascular and neuromuscular stress could be used to accurately monitor and predict middle-distance running. Eleven middle-distance runners (age 21.3±1.6 years) completed three trials of steady-state running at 11, 13, and 15 km · h–1, and test performance was compared with competitive performance (personal best times converted to standardized Mericer scores). Oxygen uptake, heart rate (HR), and stride characteristics (ground contact time [Ct], flight time, step length, and step frequency) were monitored during treadmill running with the ratio of HR:1/Ct calculated. Heart rate and stride characteristics were significantly altered (all P<0.05) with increased running speed, while the HR:1/Ct index was unchanged. Stride characteristics, heart rate, and the HR:1/Ct index were reliable measures with no mean bias and low levels of random variation. The HR:1/Ct index was strongly related to competitive performance (r=–0.80 to 0.88, P<0.01). This was primarily attributed to the association between heart rate and Mercier scores (r=–0.81 to 0.87, P<0.01), whereas ground contact time was only moderately related to competitive performance at the fastest running speed (r=–0.60, P<0.05). Simple measures associated with cardiovascular and neuromuscular stress can be reliably monitored in middle-distance runners. A HR:1/Ct index provides a stable measure at any given submaximal running speed and may provide a useful tool for monitoring and predicting middle-distance running.  相似文献   

7.
The purpose of this study was to determine if minimalist shoes improve time trial performance of trained distance runners and if changes in running economy, shoe mass, stride length, stride rate and footfall pattern were related to any difference in performance. Twenty-six trained runners performed three 6-min sub-maximal treadmill runs at 11, 13 and 15 km·h?1 in minimalist and conventional shoes while running economy, stride length, stride rate and footfall pattern were assessed. They then performed a 5-km time trial. In the minimalist shoe, runners completed the trial in less time (effect size 0.20 ± 0.12), were more economical during sub-maximal running (effect size 0.33 ± 0.14) and decreased stride length (effect size 0.22 ± 0.10) and increased stride rate (effect size 0.22 ± 0.11). All but one runner ran with a rearfoot footfall in the minimalist shoe. Improvements in time trial performance were associated with improvements in running economy at 15 km·h?1 (r = 0.58), with 79% of the improved economy accounted for by reduced shoe mass (P < 0.05). The results suggest that running in minimalist shoes improves running economy and 5-km running performance.  相似文献   

8.
ABSTRACT

The purpose of the present study was to identify factors that underlie differences among runners in stride frequency (SF) as a function of running speed. Participants (N = 256; 85.5% males and 14.5% females; 44.1 ± 9.8 years; 181.4 ± 8.4 cm; 75.3 ± 10.6 kg; mean ± SD) shared their wearable data (?Garmin Inc). Individual datasets were filtered to obtain representative relationships between stride frequency (SF) and speed per individual, representing in total 16.128 h of data. The group relationship between SF (72.82 to 94.73 strides · min?1) and running speed (V) (from 1.64 to 4.68 m · s?1) was best described with SF = 75.01 + 3.006 V. A generalised linear model with random effects was used to determine variables associated with SF. Variables and their interaction with speed were entered in a stepwise forward procedure. SF was negatively associated with leg length and body mass and an interaction of speed and age indicated that older runners use higher SF at higher speed. Furthermore, run frequency and run duration were positively related to SF. No associations were found with injury incidence, athlete experience or performance. Leg length, body mass, age, run frequency and duration were associated with SFs at given speeds.

KEY POINTS

  • On a group level, stride frequency can be described as a linear function of speed: SF (strides · min?1) = 75.01+ 3.006·speed (m · s?1) within the range of 1.64 to 4.68 m · s?1.

  • On an individual level, the SF-speed relation is best described with a second order polynomial.

  • Leg length and body mass were positively related to stride frequency while age was negatively related to stride frequency.

  • Run frequency and run duration were positively related to stride frequency, while running experience, performance and injury incidence were unrelated.

  相似文献   

9.
The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h?1 and 20 km ·h?1). VO2 and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg?1· km?1 at 12 km· h?1 and 184.8 ± 9.9 ml· kg?1· km?1 at 20 km· h?1, which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg?1·km?1 and 0.93 ± 0.07 kcal· kg?1· km?1. We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h?1. However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.  相似文献   

10.
Abstract

The purpose of this study was to investigate selected physiological changes that occurred with distance training in teenage females. Two groups of untrained teenage females were matched on [Vdot]O2 max, percent utilization of [Vdot]O 2 @ 9.66 km/hr, peak heart rate, and percent body fat. One group served as control (n = 9) while the other (n =10) underwent a 20-week training program designed to gradually increase the subjects' average mileage from 0 to 32.2 km per week. At the end of the 20 weeks, a MANOVA revealed significant mean differences within the trained group and no significant mean differences within the control group. The univariate analysis revealed that significant (p <0.05) mean differences found within the training group were for [Vdot]O 2 max (45.1 vs. 49.3 ml · kg –1 · min –1 ), percent utilization of [Vdot]O 2 @9.66 km/hr (76.5% vs. 67.5%), and economy VO 2 @9.66 km/hr (34.5vs.33.2 ml · kg –1 · min –1 ). Of the variables which exhibited significant training effects, percent utilization of [Vdot]O 2 max showed the greatest relative change, a 12.2% decrease, with [Vdot]O 2 max showing a 9.3% increase. The posttest results were similar to the research literature for training effects found for males and other age groups.  相似文献   

11.
To adhere to the principle of “exercise specificity” exercise testing should be completed using the same physical activity that is performed during exercise training. The present study was designed to assess whether aerobic step exercisers have a greater maximal oxygen consumption (max VO2) when tested using an activity specific, maximal step exercise test (SET; arms and legs) versus a maximal running test (legs only). Female aerobic step exercisers (N=18; 20.7 ± 1.5 years) performed three maximal graded exercise tests (GXTs): 2 SETs; 1 treadmill test (TMT). The SET consisted of six 3-min progressive stages of alternate lead, basic step, basic step with biceps curls, knee raise with pull-down, repeater knee with pull-down, lateral lunge with pull-down, and side squat with shoulder presses. Stepping rate was 32 steps· min?1 on an 8-in (20.32 cm) step for stages 1–3, and a 10-in (25.4 cm) step for stages 4–6. Submaximal and maximal heart rate (HR) and oxygen consumption (VO2) were recorded at the end of each stage. Test–retest reliability for the first five stages of the SET ranged from .91 to .97 for HR, and from .84 to .96 for VO2. Maximal HR was significantly greater (p =.0001) for the SET (200 ± 6.2 beats·min?1) as compared to the TMT (193 ± 7.9 beats·min?1). No significant difference was found for max VO2 (42.9 ± 8.5, 41.2 ± 5.9 ml·kg?1·min?1, p =.14). The SET was a valid and reliable protocol for assessing responses of these aerobic step exercisers; however, max VO2 from a TMT did not differ significantly from the SET. Conversely, max HR obtained from the criterion TMT was 7 beats·min?1 lower than from the SET. If a training HR for step exercise (arms and legs exercise) is prescribed based on the max HR from treadmill exercise (legs only), then the training HR should be calculated from a TMT max HR that has been increased by 7 beats·min?1 to obtain an intensity of step exercise comparable to that of running.  相似文献   

12.
Abstract

We hypothesised that experienced runners would select a stride frequency closer to the optimum (minimal energy costs) than would novice runners. In addition, we expected that optimal stride frequency could simply be determined by monitoring heart rate without measuring oxygen consumption (V?O2). Ten healthy males (mean±s: 24±2 year) with no running training experience and 10 trained runners of similar age ran at constant treadmill speed corresponding to 80% of individual ventilatory threshold. For two days, they ran at seven different stride frequencies (self-selected stride frequency±18%) imposed by a metronome. Optimal stride frequency was based on the minimum of a second-order polynomial equation fitted through steady state V?O2 at each stride frequency. Running cost (mean±s) at optimal stride frequency was higher (P < 0.05) in novice (236±31 ml O2·kg?1.km?1) than trained (189±13 ml O2·kg?1.km?1) runners. Self-selected stride frequency (mean±s; strides.min?1) for novice (77.8±2.8) and trained runners (84.4±5.3) were lower (P < 0.05) than optimal stride frequency (respectively, 84.9±5.0 and 87.1±4.8). The difference between self-selected and optimal stride frequency was smaller (P < 0.05) for trained runners. In both the groups optimal stride frequency established with heart rate was not different (P > 0.3) from optimal stride frequency based on V?O2. In each group and despite limited variation between participants, optimal stride frequencies derived from V?O2 and heart rate were related (r > 0.7; P < 0.05). In conclusion, trained runners chose a stride frequency closer to the optimum for energy expenditure than novices. Heart rate could be used to establish optimal stride frequency.  相似文献   

13.
不同步频和步幅的5km跑过程中运动员心率变化的对比研究   总被引：2，自引：0，他引：2  
段子才  张戈 《体育科学》2006,26(4):65-66
为了观察中长跑运动员长距离跑过程中步频和步幅的变化对身体机能反应的影响,8名运动员在跑台上分别采取主动加大步幅和主动减小步幅而增快步频的跑法,以相同的速度进行了两次5km跑,记录运动员在跑步过程中心率的变化并进行对比。结果显示,在相同速度5km跑的过程中,运动员采取主动减小步幅的跑法,其心率均值显著低于采取主动加大步幅的跑法。提示,长距离跑过程中,运动员采取主动减小步幅,或加大步频的跑法较为省力。  相似文献   

14.
Abstract

The purpose of this study was to determine the effects of stride length variations on ratings of perceived exertion (RPEs) in experienced recreational runners. Twenty-eight male college students were randomly divided into equal-sized treatment and control groups. The treatment group performed five 15 min altered stride length runs, each separated by a minimum of 48 hr. The five trials involved running with a freely chosen stride length (FCSL) and a FCSL altered by +14%, +7%, ?14%, and ?7%. The control group was utilized to monitor changes in subjects' RPEs as a result of practice effects developed through repeated bouts of treadmill running. Results revealed that the treatment group's local and general RPEs for the over striding runs (+14%, +7%) were significantly greater (p < .01) than RPEs recorded during the FCSL run. Additionally, there was a marginally significant difference (p < .05) in local RPEs between the FCSL run and the extreme understriding run (?14%). Analysis of variance on the control group's RPE data suggests that neither local nor general RPEs changed significantly in repeated FCSL runs across the six-week testing period. The results of this study suggest that experienced recreational runners perceive differences in exertion accompanying changes in stride length.  相似文献   

15.
Abstract

A study of the effect of fatigue on the mechanical characteristics of running during a 10,000 meter race was undertaken using high speed cinematography and a computer analysis technique. Eight highly skilled male subjects were filmed at four intervals throughout the event. An analysis of variance for trends was conducted for each of the dependent variables indicating the adjustments made by the runners that accompanied fatigue over the four stages of the event. Runners countered fatigue by changing sections of their total gait pattern (stride length, stride rate, segmental body positions) and reducing running velocity. Toward the end of the race the runners became less competent in the positioning of the foot and leg at foot-strike, which increased the potential for a retarding effect. A more extended lower limb increased the energy requirements of the recovery phase during the latter stages of the race. Fatigue caused these highly skilled runners to systematically alter their technique throughout the race. These adjustments, however, were not excessive.  相似文献   

16.

In this study, we analyzed the relationship between running economy (RE) and biomechanical parameters in a group running at the same relative intensity and same absolute velocity. Sixteen homogeneous male long-distance runners performed a test to determine RE at 4.4 m.s-1, corresponding to 11.1% below velocity at the ventilatory threshold. We found significant correlations between RE and biomechanical variables (vertical oscillation of the center of mass, stride frequency, stride length, balance time, relative stride length, range of elbow motion, internal knee, ankle angles at foot strike, and electromyographic activity of the semitendinosus and rectus femoris muscles). In conclusion, changes in running technique can influence RE and lead to improved running performance.  相似文献   

17.
ABSTRACT

Purpose: The present study aimed to compare the vertical ground reaction force responses during the performance of the stationary running water-based exercise with and without equipment at different cadences by elderly women. Method: Nineteen elderly women (age: 68.6 ± 5.0 years; body mass: 69.0 ± 9.5 kg; height: 154.9 ± 5.6 cm) completed one session consisting of the performance of the water-based stationary running with elbow flexion and extension immersed to the xiphoid process depth. The exercise was performed in three conditions, without equipment, with water-floating and with water-resistance equipment, at three cadences (80 b·min?1, 100 b·min?1 and maximal) in a randomized order. Peak and impulse of vertical ground reaction force were collected during the exercise using an underwater force plate. Repeated measures two-way ANOVA was used (α = 0.05). Results: Peak vertical ground reaction force (p < .001) and impulse (p ≤ 0.002) resulted in lower values for the water-floating use (0.42–0.48 BW and 0.07–0.13 N.s/BW) in comparison to the water-resistance equipment use (0.46–0.60 BW and 0.09–0.16 N.s/BW) and to the non-use of equipment (0.45–0.60 BW and 0.07–0.17 N.s/BW), except for the impulse at the maximal cadence. In addition, peak vertical ground reaction force at 80 b·min?1 (p = .002) and impulse at the maximal cadence (p < .001) showed lower values compared to the other cadences. Conclusion: The use of water-floating equipment minimizes the vertical ground reaction force during the stationary running water-based exercise performed by elderly women regardless of the cadence.  相似文献   

18.
Abstract

The purpose of this study was to determine the relationship between female distance running performance on a 10 km road race and body composition, maximal aerobic power ([Vdot]O2 max ), running economy (steady-state [Vdot]O2 at standardized speeds), and the fractional utilization of [Vdot]O2max at submaximal speeds (% [Vdot]O2max ). The subjects were 14 trained and competition–experienced female runners. The subjects averaged 43.7 min on the 10 km run, 53.0 ml · kg?1 · min?1 on [Vdot]O2max , and 33.9, 37.7, and 41.8 ml · kg?1 · min?1 for steady-state [Vdot]O2 at three standardized running paces (177, 196, and 215 m · min?1). The mean values for fractional utilization of aerobic capacity for these three submaximal speeds were 64.3, 71.4, and 79.3% [Vdot]O2max , respectively. Significant (p < 0.01) relationships with performance were found for [Vdot]O2max (r = ?0.66) and % [Vdot]O2max at a standardized speed (r = 0.65). No significant (p > 0.05) relationships were found between running performance and either running economy or relative body fat. As with male heterogeneous groups, trained female road racing performance is significantly related to [Vdot]O2max and % [Vdot]O2max , but not related to body composition or running economy. It was further concluded that on a 10 km road race, trained females operate at a % [Vdot]O2max similar to that of their trained male counterparts.  相似文献   

19.
Abstract

The aim of this study was to quantify the physiological loads of programmed “pre-season” and “in-season” training in professional soccer players. Data for players during each period were included for analysis (pre-season, n = 12; in-season, n = 10). We monitored physiological loading of training by measuring heart rate and rating of perceived exertion (RPE). Training loads were calculated by multiplying RPE score by the duration of training sessions. Each session was sub-categorized as physical, technical/tactical, physical and technical/tactical training. Average physiological loads in pre-season (heart rate 124 ± 7 beats · min?1; training load 4343 ± 329 Borg scale · min) were higher compared with in-season (heart rate 112 ± 7 beats · min?1; training load 1703 ± 173 Borg scale · min) (P < 0.05) and there was a greater proportion of time spent in 80–100% maximum heart rate zones (18 ± 2 vs. 5 ± 2%; P < 0.05). Such differences appear attributable to the higher intensities in technical/tactical sessions during pre-season (pre-season: heart rate 137 ± 8 beats · min?1; training load 321 ± 23 Borg scale · min; in-season: heart rate 114 ± 9 beats · min?1; training load 174 ± 27 Borg scale · min; P < 0.05). These findings demonstrate that pre-season training is more intense than in-season training. Such data indicate that these adjustments in load are a direct attempt to deliver training to promote specific training adaptations.  相似文献   

20.
ABSTRACT

Prior exercise can negatively affect movement economy of a subsequent task. However, the impact of cycling exercise on the energy cost of subsequent running is difficult to ascertain, possibly because of the use of different methods of calculating economy. We examined the influence of a simulated cycling bout on running physiological cost (running economy, heart rate and ventilation rates) and perceptual responses (ratings of perceived exertion and effort) by comparing two running bouts, performed before and after cycling using different running economy calculation methods. Seventeen competitive male triathletes ran at race pace before and after a simulated Olympic-distance cycling bout. Running economy was calculated as V?O2 (mL?kg?1?min?1), oxygen cost (EO2, mL?kg?1?m?1) and aerobic energy cost (Eaer, J?kg?1?m?1). All measures of running economy and perceptual responses indicated significant alterations imposed by prior cycling. Despite a good level of agreement with minimal bias between calculation methods, differences (p < 0.05) were observed between Eaer and both V?O2 and EO2. The results confirmed that prior cycling increased physiological cost and perceptual responses in a subsequent running bout. It is recommended that Eaer be calculated as a more valid measure of running economy alongside perceptual responses to assist in the identification of individual responses in running economy following cycling.  相似文献   

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