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1.
Research has focused on the effects of acute strike pattern modifications on lower extremity joint stiffness and running economy (RE). Strike pattern modifications on running biomechanics have mostly been studied while runners complete short running bouts. This study examined the effects of an imposed forefoot strike (FFS) on RE and ankle and knee joint stiffness before and after a long run in habitual rearfoot strike (RFS) runners. Joint kinetics and RE were collected before and after a long run. Sagittal joint kinetics were computed from kinematic and ground reaction force data that were collected during over-ground running trials in 13 male runners. RE was measured during treadmill running. Knee flexion range of motion, knee extensor moment and ankle joint stiffness were lower while plantarflexor moment and knee joint stiffness were greater during imposed FFS compared with RFS. The long run did not influence the difference in ankle and knee joint stiffness between strike patterns. Runners were more economical during RFS than imposed FFS and RE was not influenced by the long run. These findings suggest that using a FFS pattern towards the end of a long run may not be mechanically or metabolically beneficial for well-trained male RFS runners.  相似文献   

2.
The aim of the present study was to examine the factorial validity of the Test of Performance Strategies (TOPS; Thomas et al., 1999) among adolescent athletes using confirmatory factor analysis. The TOPS was designed to assess eight psychological strategies used in competition (i.e. activation, automaticity, emotional control, goal-setting, imagery, negative thinking, relaxation and self-talk,) and eight used in practice (the same strategies except negative thinking is replaced by attentional control). National-level athletes (n = 584) completed the 64-item TOPS during training camps. Fit indices provided partial support for the overall measurement model for the competition items (robust comparative fit index = 0.92, Tucker-Lewis index = 0.88, root mean square error of approximation = 0.05) but minimal support for the training items (robust comparative fit index = 0.86, Tucker-Lewis index = 0.81, root mean square error of approximation = 0.06). For the competition items, the automaticity, goal-setting, relaxation and self-talk scales showed good fit, whereas the activation, emotional control, imagery and negative thinking scales did not. For the practice items, the attentional control, emotional control, goal-setting, imagery and self-talk scales showed good fit, whereas the activation, automaticity and relaxation scales did not. Overall, it appears that the factorial validity of the TOPS for use with adolescents is questionable at present and further development is required.  相似文献   

3.
The aim of the present study was to examine the factorial validity of the Test of Performance Strategies (TOPS; Thomas et al., ) among adolescent athletes using confirmatory factor analysis. The TOPS was designed to assess eight psychological strategies used in competition (i.e. activation, automaticity, emotional control, goal-setting, imagery, negative thinking, relaxation and self-talk,) and eight used in practice (the same strategies except negative thinking is replaced by attentional control). National-level athletes (n?=?584) completed the 64-item TOPS during training camps. Fit indices provided partial support for the overall measurement model for the competition items (robust comparative fit index?=?0.92, Tucker-Lewis index?=?0.88, root mean square error of approximation?=?0.05) but minimal support for the training items (robust comparative fit index?=?0.86, Tucker-Lewis index?=?0.81, root mean square error of approximation?=?0.06). For the competition items, the automaticity, goal-setting, relaxation and self-talk scales showed good fit, whereas the activation, emotional control, imagery and negative thinking scales did not. For the practice items, the attentional control, emotional control, goal-setting, imagery and self-talk scales showed good fit, whereas the activation, automaticity and relaxation scales did not. Overall, it appears that the factorial validity of the TOPS for use with adolescents is questionable at present and further development is required.  相似文献   

4.
Improvements in running economy (RE) are thought to lead to improvements in running performance (P). Multiple interventions have been designed with the aim of improving RE in middle and long-distance runners. The aim of this study was to assess the effect of interventions of at least 2-weeks’ duration on RE and P and to determine whether there is a relationship between changes in RE (ΔRE) and changes in running performance (ΔP). A database search was carried out in Web of Science, Scopus and SPORTDiscus. In accordance with a PRISMA checklist 10 studies reporting 12 comparisons between interventions and controls were included in the review. There was no correlation between percentage ΔRE and percentage ΔP (r = 0.46, P = 0.936, 12 comparisons). There was a low risk of reporting bias but an unclear risk of bias for other items. Meta-analyses found no statistically significant differences between interventions and controls for RE (SMD (95% CI) = ?0.37 (?1.43, 0.69), 204 participants, p = 0.49) or for P (SMD (95% CI) = ?0.65 (?26.02, 24.72, 204 participants, p = 0.99). There is a need for studies of greater statistical power, methodological quality, duration and homogeneity of intervention and population. Standardised measures of performance and greater control over non-intervention training are also required.  相似文献   

5.
The aims of the present study were to determine whether available "fasting" and oral glucose tolerance test-derived insulin sensitivity indices could effectively discriminate between individuals with higher than normal insulin sensitivity, and whether they would all provide similar information in clinical practice. Sprint runners (n = 8), endurance runners (n = 8) and sedentary controls (n = 7) received a 75-g oral glucose tolerance test. All participants were healthy lean males, aged 21-29 years. Besides glucose and insulin responses, a total of nine such indices were computed. Fasting as well as post-load glucose concentrations were similar in the three groups, while basal plasma insulin and the insulinaemic response to glucose were both higher in untrained individuals (at P < 0.05 and P < 0.02, respectively). There were no differences between endurance and sprint runners. The results for insulin sensitivity, however, were quite variable: three indices showed that both groups of athletes were more insulin-sensitive than controls; three indicated that this was the case for endurance runners only; one indicated that this was the case for sprint runners only; and two showed that sprint runners were more insulin-sensitive than either sedentary individuals or endurance runners (all differences were significant at P < 0.05). Controlling for total body weight or lean mass did not effectively resolve this disagreement. Apparently, the various insulin sensitivity indices examined provided different quantitative and qualitative information, despite insulin action being greater in both groups of athletes relative to controls, as reflected by their similar glucose tolerance with lower insulin concentrations. We suggest, therefore, that the use and interpretation of such indices among physically active individuals be made with caution.  相似文献   

6.
The aims of the present study were to determine whether available “fasting” and oral glucose tolerance test-derived insulin sensitivity indices could effectively discriminate between individuals with higher than normal insulin sensitivity, and whether they would all provide similar information in clinical practice. Sprint runners (n = 8), endurance runners (n = 8) and sedentary controls (n = 7) received a 75-g oral glucose tolerance test. All participants were healthy lean males, aged 21?–?29 years. Besides glucose and insulin responses, a total of nine such indices were computed. Fasting as well as post-load glucose concentrations were similar in the three groups, while basal plasma insulin and the insulinaemic response to glucose were both higher in untrained individuals (at P?<?0.05 and P?<?0.02, respectively). There were no differences between endurance and sprint runners. The results for insulin sensitivity, however, were quite variable: three indices showed that both groups of athletes were more insulin-sensitive than controls; three indicated that this was the case for endurance runners only; one indicated that this was the case for sprint runners only; and two showed that sprint runners were more insulin-sensitive than either sedentary individuals or endurance runners (all differences were significant at P?<?0.05). Controlling for total body weight or lean mass did not effectively resolve this disagreement. Apparently, the various insulin sensitivity indices examined provided different quantitative and qualitative information, despite insulin action being greater in both groups of athletes relative to controls, as reflected by their similar glucose tolerance with lower insulin concentrations. We suggest, therefore, that the use and interpretation of such indices among physically active individuals be made with caution.  相似文献   

7.
郜卫峰 《体育科学》2012,32(5):49-57
目的:利用便携式肺功能仪,在场地条件下测试中跑运动员4种次极限跑速时的跑步经济性(RE),比较以时间耗氧(ml/kg/min)、距离耗氧(ml/kg/km)和距离耗能(kcal/kg/km)单位评价RE的有效性。方法:10名中跑运动员在标准田径场跑道上完成1次递增负荷测试和1次持续4个回合的恒定负荷测试。通过递增负荷测试获取最大耗氧量(VO2max)和无氧阈(AT),并分别以70%、80%、90%、105%AT强度完成5～10min恒定负荷测试,取稳态耗氧量及相关呼吸指标计算3种不同单位表示时的RE。结果:3种单位表示的RE在两两间均呈现出非常显著的相关关系(P<0.01)。随运动强度的增高,单位时间的耗氧在每级间均显著增高(P<0.05);单位距离的耗氧则无明显变化(P>0.05),且在80%～105%AT强度间出现微弱的降低;单位距离的能耗在70%～90%AT间缓慢增高(P>0.05),但在90%～105%AT间增高显著(P<0.05);呼吸交换率(RER)则在80%～105%AT间出现了不同程度地显著提高(80%～90%AT:P<0.05,90%～105%AT:P<0.01)。结论:无论是时间耗氧单位还是距离耗氧单位,都忽略了底物利用的不同对耗氧量的影响,无法有效评定RE。能量单位更符合RE的本质特征,与运动实践更加相关,是评定RE的有效单位。  相似文献   

8.
The effectiveness of a nap as a recovery strategy for endurance exercise is unknown and therefore the present study investigated the effect of napping on endurance exercise performance. Eleven trained male runners completed this randomised crossover study. On two occasions, runners completed treadmill running for 30?min at 75% ?O2max in the morning, returning that evening to run for 20?min at 60% ?O2max, and then to exhaustion at 90% ?O2max. On one trial, runners had an afternoon nap approximately 90?min before the evening exercise (NAP) whilst on the other, runners did not (CON). All runners napped (20?±?10?min), but time to exhaustion (TTE) was not improved in all runners (NAP 596?±?148?s vs. CON 589?±?216?s, P?=?.83). Runners that improved TTE after the nap slept less at night than those that did not improve TTE (night-time sleep 6.4?±?0.7?h vs. 7.5?±?0.4?h, P?r2 ? =??0.76, P?=?.001). In runners that improved TTE, ratings of perceived exertion (RPE) were lower during the TTE on NAP than CON compared to runners that did not improve (?0.4?±?0.6 vs. 0?±?0, P?=?.05). Reduced exercising sense of effort (RPE) may account for the improved TTE after the nap. In conclusion, a short afternoon nap improves endurance performance in runners that obtain less than 7?h night-time sleep.  相似文献   

9.
A number of studies have shown that attentional focus instructions can effect running economy. This study assessed spiroergometry, as well as running kinematics as a possible mechanism to explain these effects. Twelve runners had to focus their attention on either their running movement, their breathing or on a video while running on a treadmill at a set, submaximum speed. Spiroergometry and running kinematics were measured. Results revealed worse running economy in both internal focus conditions (breathing and movement) compared to the external focus condition (video), replicating previous findings. In addition, vertical oscillation during the running movement was elevated in the movement compared to the video condition, indicating a less efficient running style. No changes in kinematics were found for the breathing compared to the video condition. Therefore, consciously focusing on the running movement moves runners away from their optimised running pattern and leads to detriments in economy. The decreases in running economy in the breathing condition can be better explained by changes in breathing patterns.  相似文献   

10.
PurposeWe compared running economy (RE) and 3-km time-trial (TT) variables of runners wearing Nike Vaporfly 4% (VP4), Saucony Endorphin lightweight racing flats (FLAT), and their habitual running (OWN) footwear.MethodsEighteen male recreational runners (age = 33.5 ± 11.9 year (mean ± SD), peak oxygen uptake (VO2peak) = 55.8 ± 4.4 mL/kg·min) attended 4 sessions approximately 7 days apart. The first session consisted of a VO2peak test to inform subsequent RE speeds set at 60%, 70%, and 80% of the speed eliciting VO2peak. In subsequent sessions, treadmill RE and 3-km TTs were assessed in the 3 footwear conditions in a randomized, counterbalanced crossover design.ResultsOxygen consumption (mL/kg·min) was less in VP4 (from 4.3% to 4.4%, p ≤ 0.002) and FLAT (from 2.7% to 3.4%, p ≤ 0.092) vs. OWN across intensities, with a non-significant difference between VP4 and FLAT (1.0%–1.7%, p ≥ 0.292). Findings related to energy cost (W/kg) and energetics cost of transport (J/kg·m) were comparable. VP4 3-km TT performance (11:07.6 ± 0:56.6 mm:ss) was enhanced vs. OWN by 16.6 s (2.4%, p = 0.005) and vs. FLAT by 13.0 s (1.8%, p = 0.032). The 3-km times between OWN and FLAT (0.5%, p = 0.747) were similar. Most runners (n = 11, 61%) ran their fastest TT in VP4.ConclusionOverall, VP4 improved laboratory-based RE measures in male recreational runners at relative speeds compared to OWN, but the RE improvements in VP4 were not significant vs. FLAT. More runners exhibited better treadmill TT performances in VP4 (61%) vs. FLAT (22%) and OWN (17%). The variability in RE (–10.3% to 13.3%) and TT (–4.7% to 9.3%) improvements suggests that responses to different types of shoes are individualized and warrant further investigation.  相似文献   

11.
The purpose of this study was to investigate the relationship between running economy (RE) and performance in a homogenous group of competitive Kenyan distance runners. Maximal aerobic capacity (VO2max) (68.8 ± 3.8 ml?kg?1?min?1) was determined on a motorised treadmill in 32 Kenyan (25.3 ± 5.0 years; IAAF performance score: 993 ± 77 p) distance runners. Leg anthropometry was assessed and moment arm of the Achilles tendon determined. While Achilles moment arm was associated with better RE (r2 = 0.30, P = 0.003) and upper leg length, total leg length and total leg length to body height ratio were correlated with running performance (r = 0.42, P = 0.025; r = 0.40, P = 0.030 and r = 0.38, P = 0.043, respectively), RE and maximal time on treadmill (tmax) were not associated with running performance (r = ?0.01, P = 0.965; r = 0.27; P = 0.189, respectively) in competitive Kenyan distance runners. The dissociation between RE and running performance in this homogenous group of runners would suggest that RE can be compensated by other factors to maintain high performance levels and is in line with the idea that RE is only one of many factors explaining elite running performance.  相似文献   

12.
目的:观察不同水平中长跑运动员跑步效能是否存在差异。方法:江苏田径队一、二线中长跑运动员,男性,各6名;便携式氧代谢测试仪器测试个人最好成绩平均速度下的跑步能效(RE,ml.kg-1.m-1)。结果:高水平组的跑步能效显著低于普通组的跑步能效(11.2±0.35,11.9±0.6,P=0.043)结论:本研究中高水平组运动员具有更好的运动节省能力。  相似文献   

13.
This study explored possible contributing factors to gastrointestinal distress, including endotoxemia, hyperthermia, dehydration and nutrition, during a 161-km ultramarathon. Thirty runners participated in the study and 20 finished the race. At three checkpoints and the finish, runners were interviewed to assess the incidence and severity of 12 gastrointestinal symptoms and to determine dietary intake. Core temperature was measured at the same locations. Runners were weighed pre-race, at the three checkpoints and the finish to monitor hydration status. Blood markers for endotoxemia (sCD14) and inflammation (interleukin-6 and C-reactive protein) were measured pre- and post-race. Gastrointestinal symptoms were experienced by most runners (80%), with nausea being the most common complaint (60%). Runners with nausea experienced significantly greater (P = 0.02) endotoxemia than those without nausea (sCD14 mean increase 0.7 versus 0.5 µg · mL?1). There was a significant positive correlation (r = 0.652, P = 0.005) between nausea severity and endotoxemia level. Inflammatory response, core temperature, hydration level and race diet were similar between runners with and without nausea. This study links endotoxemia to nausea in ultramarathon runners. Other possible contributing factors to nausea such as hyperthermia, dehydration and nutrition did not appear to play a role in the symptomatic runners in this study.  相似文献   

14.
The biomechanical profile of high-level endurance runners may represent a useful model that could be used for developing training programmes designed to improve running style. This study, therefore, sought to compare the biomechanical characteristics of high-performance and recreational runners. Kinematic and kinetic measurements were taken during overground running from a cohort of 14 high-performance (8 male) and 14 recreational (8 male) runners, at four speeds ranging from 3.3 to 5.6?m?s?1. Two-way ANOVA analysis was then used to explore group and speed effects and principal component analysis used to explore the interdependence of the tested variables. The data showed the high-performance runners to have a gait style characterised by an increased vertical velocity of the centre of mass and a flight time that was 11% longer than the recreational group. The high-performance group were also observed to adopt a forefoot strike pattern, to contact the ground with their foot closer to their body and to have a larger ankle moment. Importantly, although observed group differences were mostly independent of speed, the tested variables showed a high degree of interdependence suggesting an underlying unitary phenomenon. This is the first study to compare high-performance and recreational runners across a full range of kinematic and kinetic variables. The results suggest that high-performance runners maintain stride length with a prolonged aerial phase, rather than by landing with a more extended knee. These findings motivate future intervention studies that should investigate whether recreational runners could benefit from instruction to decrease shank inclination at foot contact.  相似文献   

15.
Runners tend to shift from a rearfoot to a forefoot strike pattern when running barefoot. However, it is unclear how the first attempts at running barefoot affect habitually rearfoot shod runners. Due to the inconsistency of their recently adopted barefoot technique, a number of new barefoot-related running injuries are emerging among novice barefoot runners. The aim of this study was therefore to analyse the influence of three running conditions (natural barefoot [BF], barefoot with a forced rearfoot strike [BRS], and shod [SH]) on muscle activity and impact accelerations in habitually rearfoot shod runners. Twenty-two participants ran at 60% of their maximal aerobic speed while foot strike, tibial and head impact accelerations, and tibialis anterior (TA), peroneus longus (PL), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) muscle activity were registered. Only 68% of the runners adopted a non-rearfoot strike pattern during BF. Running BF led to a reduction of TA activity as well as to an increase of GL and GM activity compared to BRS and SH. Furthermore, BRS increased tibial peak acceleration, tibial magnitude and tibial acceleration rate compared to SH and BF. In conclusion, 32% of our runners showed a rearfoot strike pattern at the first attempts at running barefoot, which corresponds to a running style (BRS) that led to increased muscle activation and impact accelerations and thereby to a potentially higher risk of injury compared to running shod.  相似文献   

16.
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17.

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   

18.
The purpose of the study was to relate three determinants of distance running success, (a) maximal oxygen consumption (VO2max), (b) ventilatory threshold (VT), and (c) running economy (RE), to actual running time in a 5-km race (ART). Twenty-four female runners (M age = 15.9 years) from four high school teams that competed at the Massachusetts All-State 5-km Cross Country Championship Meet and placed 1st, 7th, 19th, and 20th were tested in the laboratory. The mean VO2max of these runners was 61.7 ml.kg-1.min-1, HRmax 201 b.min-1, VEmax 100 L.min-1, and RER 1.10. The VT occurred at 79% of the VO2max, and HR of 184 b.min-1 (92% of HRmax). The velocity at VT (vVT) and velocity at VO2max (vVO2max) was correlated with ART, r(22) = .78 and .77 (p less than .001), respectively. The VO2 at VT and at maximal exercise was correlated with ART by r(22) = -.66 and -.69 (p less than .001), respectively. The VO2 at 215 m.min-1 (8 mph) was poorly related to ART, r(22) = -.05, p greater than .05. It was concluded that either of the derived variables vVT and vVO2max appear to explain significant variation in distance running performance among adolescent female cross country runners.  相似文献   

19.
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20.
我国优秀女子长跑运动员高原训练模式初探   总被引：3，自引：0，他引：3  
高原训练是我国长跑、马拉松项目冲出亚洲、走向世界的有效途径。如何更加充分地利用高原自然环境，进一步发挥高原训练效果，提高高原训练的成功率，还需要不断探索。一个完整的高原训练过程包括平原大运动量训练阶段、高原大强度训练阶段和赛前平原大强度训练阶段3个部分，应妥善处理三者之间的负荷关系。  相似文献   

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