Equipment set-up among Olympic sprint and slalom kayak paddlers

The anthropometry and equipment set-up for sprint (31 male; 11 female) and slalom (12 male; 12 female) kayak paddlers who competed at the 2000 Olympic Games in Sydney were measured in the 15 day period before competition. This paper provides normative data for equipment set-up in these sports, as well as information about differences in rigging and paddle dimensions between sprint and slalom kayak paddlers. These differences were consistent for both male and female athletes, with sprint paddlers seated higher and using longer paddles with longer, though narrower, blades (p < 0.0001). Among male sprint paddlers, only minor differences in equipment set-up were found between competitors ranked in the top 10 places compared to the rest of the field. Considering all male paddlers initially, then sprint paddlers alone, significant (p < 0.01) regression equations were developed for the prediction of foot bar distance (r2 = 0.482 and 0.589 respectively) and hand grip distance (r2 = 0.400 and 0.541 respectively). The process of fine tuning equipment set-up often requires hours of practice with subjective feedback from the athlete. The normative data presented in this paper should assist coaches with this process as their athletes evolve toward their individual optimum set-up.     

我国优秀女子短跑运动员100m跑速度节奏分析

越来越多的研究发现:从整体上把握百米跑全程速度节奏是进一步提高成绩的有效方法。为此,通过对参加第九届全运会女子百米跑决赛运动员以及世界优秀女子短跑运动员的百米跑全程速度节奏对比分析发现:与世界优秀女子短跑运动员相比,我国优秀女子短跑运动员在贯彻百米跑的整体观,合理使用短跑所需体能等方面尚有一定差距,这是影响其百米成绩进一步提高的主要原因之一。     

Acceleration and sprint profiles of a professional elite football team in match play

Abstract

The aim of this study was to characterise the acceleration and sprint profiles of elite football match play in one Norwegian elite football team (Rosenborg FC). Fifteen professional players in five playing positions took part in the study (n = 101 observations). Player movement was recorded during every domestic home game of one full season (n = 15) by an automatic tracking system based on microwave technology. Each player performed 91 ± 21 accelerations per match, with a lower number in the second compared with the first half (47 ± 12 vs. 44 ± 12). Players in lateral positions accelerated more often compared to players in central positions (98.3 ± 20.5 vs. 85.3 ± 19.5, p < 0.05). Average sprint distance was 213 ± 111 m distributed between 16.6 ± 7.9 sprints, with no differences between first (106 ± 60 m, 8.2 ± 4.2 sprints) and second halves (107 ± 72 m, 8.3 ± 4.8 sprints). Players in lateral positions sprinted longer distances (287 ± 211 m vs. 160 ± 76 m, p < 0.05) and tended to sprint more often (21.6 ± 7.8 vs. 13.0 ± 5.7, p = 0.064) compared to players in central positions. We found more walking and less of the more intense activities during the last third of the season compared to the first. The main finding in this study was that Norwegian elite players had substantially less number of accelerations and fewer but longer sprints than previous studies reported for higher-ranked leagues. Also, less high-intensity activity was found towards the end of the season. Ultimately, these data provide useful information for the fitness coach (1) in planning of position-specific football training and (2) to avoid the decline in high-intensity activities the last third of the competitive season.     

我国优秀男子龙舟运动员身体素质评价模型的研究

运用文献资料法,数理统计法,专家访谈法等多种研究方法,对2009年全国龙舟锦标赛、中华龙舟大赛总决赛、2010年亚运会全国选拔赛中各单项前六名的30支优秀男子龙舟队伍的运动员身体素质指标进行研究,通过研究分析,确立我国优秀男子龙舟运动员身体素质的评价模型。结果表明:1)我国优秀男子龙舟运动员的身体素质主要由力量、耐力、柔韧、速度、灵敏5个因子构成,其中力量因子和耐力因子的载荷贡献率较大。2)我国优秀男子龙舟运动员的身体素质特征表现为:力量较大,速度快,耐力突出,反应灵敏,柔韧性很好等特点。3)根据各素质指标测得数据统计分析,按其的权重比例构建评价体系模型,为我国优秀男子龙舟运动员的科学选材和训练提供重要的参考依据。     

Changes in mechanical properties of sprinting during repeated sprint in elite rugby sevens athletes

This study aimed to analyse fatigue-induced changes in mechanical sprinting properties during a specific repeated-sprint test in elite rugby sevens athletes. Twenty elite rugby sevens players performed ten 40?m sprints on a 30?s cycle with participant’s running back and forth in a marked lane. Radar was used to assess maximal overground sprint performance over each 40?m. Macroscopic mechanical properties (maximal horizontal force (F₀), maximal horizontal power (P_max), maximal ratio of horizontal force (RF_peak), decrease in the ratio of horizontal-to-total force (D_RF), total force and maximal sprinting velocity (v₀)) were drawn from horizontal force velocity relationships, using a validated method applied to the speed–time data. Fatigue-induced changes were analysed comparing the first sprint to an average of 2^nd-4^th, 5^th-7^th and 8^th-10^th. Repeated-sprint ability (RSA) testing induced substantial changes in the maximal velocity component, with a decrease (–15%) in v₀ (effect size (ES)?=?–2.46 to –4.98), and to a lower extent (–5.9%) in the maximal force component F₀ (ES?=?–0.59). D_RF moderately decreased (14%; ES=–0.76–1.11), and RF_peak largely decreased in the later sprints (ES?=?–0.32 to –1.27). Fatigue observed in this RSA test appeared to have a greater effect on the technical ability to produce horizontal force at high velocities, likely due to an alteration in the ability to maintain horizontally oriented force application when velocity increases rather than during the initial acceleration phase, but also the overall force production capacity. The ability to maintain forward-oriented force at high velocities is of central importance for identifying fatigue and monitoring load.     

Biomechanical analysis of dragon boat paddling: A comparison of elite and sub-elite paddlers

Abstract

In this study, video and force analysis techniques were used to distinguish between dragon boat paddlers of different ability. Six elite paddlers (three males, three females) and six sub-elite paddlers (two males, four females) were compared during high-intensity paddling (80–90 strokes · min^?1). Video filming was conducted for two-dimensional kinematic analysis and an instrumented paddle was used to collect force data. Paddling efficiency, paddle force characteristics, and paddler kinematic variables were measured. Elite paddlers achieved higher paddling efficiency than sub-elite paddlers (elite: 76 ± 4%; sub-elite: 67 ± 10%; P = 0.080). Elite paddlers also showed higher peak force (elite: 16.3 ± 4.8 N · kg^?2/3; sub-elite: 11.4 ± 2.6 N · kg^?2/3; P = 0.052), average force (elite: 7.9 ± 2.8 N · kg^?2/3; sub-elite: 5.5 ± 1.4 N · kg^?2/3; P = 0.084), and impulse (elite: 3.0 ± 0.9 (N · s) · kg^?2/3; sub-elite: 1.9 ± 0.4 (N · s) · kg^?2/3; P = 0.026) than sub-elite paddlers, but these three results should be viewed with caution due to the small sample size and the unequal number of males and females in the two groups. Superior technique and greater strength enable the elite paddlers to achieve higher paddling efficiency. Paddlers use different joint movement patterns to develop propulsion, which are reflected in variations in the force–time curve.     

Sprint kayaking and canoeing performance prediction based on the relationship between maturity status,anthropometry and physical fitness in young elite paddlers

This study aimed to identify the maturity-related differences and its influence on the physical fitness, morphological and performance characteristics of young elite paddlers. In total, 89 kayakers and 82 canoeists, aged 13.69 ± 0.57 years (mean ± s), were allocated in three groups depending on their age relative to the age at peak height velocity (pre-APHV, circum-APHV and post-APHV) and discipline (kayak and canoe). Nine anthropometric variables, a battery of four physical fitness tests (overhead medicine ball throw, countermovement jump, sit-and-reach test and 20 m multistage shuttle run test) and three specific performance tests (1000, 500 and 200 m) were assessed. Both disciplines presented significant maturity-based differences in all anthropometric parameters (except for fat and muscle mass percentage), overhead medicine ball throw and all performance times (pre > circum > post; P < 0.05). Negative and significant correlations (P < 0.01) were detected between performance times, chronological age and anthropometry (body mass, height, sitting height and maturity status), overhead medicine ball throw and sit and reach for all distances. These findings confirm the importance of maturity status in sprint kayaking and canoeing since the more mature paddlers were also those who revealed largest body size, physical fitness level and best paddling performance. Additionally, the most important variables predicting performance times in kayaking and canoeing were maturity status and chronological age, respectively.     

Mechanical power,thrust power and propelling efficiency: relationships with elite sprint swimming performance

The purpose of this study was to explore the relationships between mechanical power, thrust power, propelling efficiency and sprint performance in elite swimmers. Mechanical power was measured in 12 elite sprint male swimmers: (1) in the laboratory, by using a whole-body swimming ergometer (W'_TOT) and (2) in the pool, by measuring full tethered swimming force (F_T) and maximal swimming velocity (V_max): W'_T = F_T · V_max. Propelling efficiency (η_P) was estimated based on the “paddle wheel model” at V_max. V_max was 2.17 ± 0.06 m · s^?1, η_P was 0.39 ± 0.02, W'_T was 374 ± 62 W and W'_TOT was 941 ± 92 W. V_max was better related to W'_T (useful power output: R = 0.943, P < 0.001) than to W'_TOT (total power output: R = 0.744, P < 0.01) and this confirms the use of the full tethered test as a valid test to assess power propulsion in sprinters and to estimate swimming performance. The ratio W'_T/W'_TOT (0.40 ± 0.04) represents the fraction of total mechanical power that can be utilised in water (e.g., η_P) and was indeed the same as that estimated based on the “paddle wheel model”; this supports the use of this model to estimate η_P in swimming.     

Profiling elite male 100-m sprint performance: The role of maximum velocity and relative acceleration

Purpose:This study aimed to determine the accuracy of a 4 split time modelling method to generate velocity-time and velocity-distance variables in elite male 100-m sprinters and subsequently to assess the roles of key sprint parameters with respect to 100-m sprint performance.Additionally,this study aimed to assess the differences between faster and slower sprinters in key sprint variables that have not been assessed in previous work.Methods:Velocity-time and velocity-distance curves were generated using a mono-exponential function from 4 split times for 82 male sprinters during major athletics competitions.Key race variables-maximum velocity,the acceleration time constant(τ),and percentage of velocity lost(vLoss)-were derived for each athlete.Athletes were divided into tertiles,based on 100-m time,with the first and third tertiles considered to be the faster and slower groups,respectively,to facilitate further analysis.Results:Modelled split times and velocities displayed excellent accuracy and close agreement with raw measures(range of mean bias was-0.2%to 0.2%,and range of intraclass correlation coefficients(ICCs)was 0.935 to 0.999)except for 10-m time(mean bias was 1.6%±1.3%,and the ICC was 0.600).The 100-m sprint performance time and all 20-m split times had a significant near-perfect negative correlation with maximum velocity(r≥-0.90)except for the 0 to 20-m split time,where a significantly large negative correlation was found(r=-0.57).The faster group had a significantly higher maximum velocity andτ(p<0.001),and no significant difference was found for vLoss(p=0.085).Conclusion:Coaches and researchers are encouraged to utilize the 4 split time method proposed in the current study to assess several key race variables that describe a sprinter’s performance capacities,which can be subsequently used to further inform training.     

The effect of individualised sprint training in elite female team sport athletes: A pilot study

ABSTRACT

This study aimed to evaluate whether an individualised sprint-training program was more effective in improving sprint performance in elite team-sport players compared to a generalised sprint-training program. Seventeen elite female handball players (23 ± 3 y, 177 ± 7 cm, 73 ± 6 kg) performed two weekly sprint training sessions over eight weeks in addition to their regular handball practice. An individualised training group (ITG, n = 9) performed a targeted sprint-training program based on their horizontal force-velocity profile from the pre-training test. Within ITG, players displaying the lowest, highest and mid-level force-velocity slope values relative to body mass were assigned to a resisted, an assisted or a mixed sprint-training program (resisted sprinting in the first half and assisted sprinting in the second half of the intervention period), respectively. A control group (CG, n = 8) performed a generalised sprint-training program. Both groups improved 30-m sprint performance by ~1% (small effect) and maximal velocity sprinting by ~2% (moderate effect). Trivial or small effect magnitudes were observed for mechanical outputs related to horizontal force- or power production. All between-group differences were trivial. In conclusion, individualised sprint-training was no more effective in improving sprint performance than a generalised sprint-training program.     

A biomechanical comparison of initial sprint acceleration performance and technique in an elite athlete with cerebral palsy and able-bodied sprinters

Abstract

Cerebral palsy is known to generally limit range of motion and force producing capability during movement. It also limits sprint performance, but the exact mechanisms underpinning this are not well known. One elite male T36 multiple-Paralympic sprint medallist (T36) and 16 well-trained able-bodied (AB) sprinters each performed 5–6 maximal sprints from starting blocks. Whole-body kinematics (250 Hz) in the block phase and first two steps, and synchronised external forces (1,000 Hz) in the first stance phase after block exit were combined to quantify lower limb joint kinetics. Sprint performance (normalised average horizontal external power in the first stance after block exit) was lower in T36 compared to AB. T36 had lower extensor range of motion and peak extensor angular velocity at all lower limb joints in the first stance after block exit. Positive work produced at the knee and hip joints in the first stance was lower in T36 than AB, and the ratio of positive:negative ankle work produced was lower in T36 than AB. These novel results directly demonstrate the manner in which cerebral palsy limits performance in a competition-specific sprint acceleration movement, thereby improving understanding of the factors that may limit performance in elite sprinters with cerebral palsy.     

Effect of the movement speed of resistance training exercises on sprint and strength performance in concurrently training elite junior sprinters

The aim of this study was to determine the effects of 7 weeks of high- and low-velocity resistance training on strength and sprint running performance in nine male elite junior sprint runners (age 19.0 - 1.4 years, best 100 m times 10.89 - 0.21 s; mean - s ). The athletes continued their sprint training throughout the study, but their resistance training programme was replaced by one in which the movement velocities of hip extension and flexion, knee extension and flexion and squat exercises varied according to the loads lifted (i.e. 30-50% and 70-90% of 1-RM in the high- and low-velocity training groups, respectively). There were no between-group differences in hip flexion or extension torque produced at 1.05, 4.74 or 8.42 rad·s -1 , 20 m acceleration or 20 m 'flying' running times, or 1-RM squat lift strength either before or after training. This was despite significant improvements in 20 m acceleration time ( P ? 0.01), squat strength ( P ? 0.05), isokinetic hip flexion torque at 4.74 rad·s -1 and hip extension torque at 1.05 and 4.74 rad·s -1 for the athletes as a whole over the training period. Although velocity-specific strength adaptations have been shown to occur rapidly in untrained and non-concurrently training individuals, the present results suggest a lack of velocity-specific performance changes in elite concurrently training sprint runners performing a combination of traditional and semi-specific resistance training exercises.     

Effect of the movement speed of resistance training exercises on sprint and strength performance in concurrently training elite junior sprinters

The aim of this study was to determine the effects of 7 weeks of high- and low-velocity resistance training on strength and sprint running performance in nine male elite junior sprint runners (age 19.0+/-1.4 years, best 100 m times 10.89+/-0.21 s; mean +/- s). The athletes continued their sprint training throughout the study, but their resistance training programme was replaced by one in which the movement velocities of hip extension and flexion, knee extension and flexion and squat exercises varied according to the loads lifted (i.e. 30-50% and 70-90% of 1-RM in the high- and low-velocity training groups, respectively). There were no between-group differences in hip flexion or extension torque produced at 1.05, 4.74 or 8.42 rad x s(-1), 20 m acceleration or 20 m 'flying' running times, or 1-RM squat lift strength either before or after training. This was despite significant improvements in 20 m acceleration time (P < 0.01), squat strength (P < 0.05), isokinetic hip flexion torque at 4.74 rad x s(-1) and hip extension torque at 1.05 and 4.74 rad x s(-1) for the athletes as a whole over the training period. Although velocity-specific strength adaptations have been shown to occur rapidly in untrained and nonconcurrently training individuals, the present results suggest a lack of velocity-specific performance changes in elite concurrently training sprint runners performing a combination of traditional and semi-specific resistance training exercises.     

Effects of short-term detraining on measures of obesity and glucose tolerance in elite athletes

Athletes frequently adjust their training volume in line with their athletic competition schedule, onset of sport injury, and retirement. Whether maintenance of partial training activity during the detraining period can preserve optimal body composition and insulin sensitivity is currently unknown. Sixteen elite kayak athletes (mean VO2max: 58.5 ml.kg(-1).min(-1), s = 1.77) were randomly assigned to a totally detrained group (age: 20.8 years, s = 0.7; body mass index: 23.74, s = 0.54) or partially detrained group (age: 21.8 years, s = 0.7; body mass index: 23.20, s = 1.02), whereby totally detrained participants terminated their training routine completely and the partially detrained participants preserved approximately 50% of their previous training duration with equivalent intensity for one month. Body mass, waist circumference, oral glucose tolerance test, insulin, leptin, cortisol, and testosterone were measured during the trained state and after detraining. Waist circumferences for both the partially detrained and totally detrained groups were significantly elevated after detraining, with no group difference. However, body mass was reduced in both groups. Significant elevations in the area under the curve for insulin and fasted leptin with detraining were observed. These changes were greater in the totally detrained participants. In conclusion, the present results show that maintaining partial training activity cannot prevent an increase in waist circumference. During the detraining period, the magnitude of increase in plasma insulin and leptin concentrations was regulated in an activity-dependent manner.     

Repeated-sprint performance and plasma responses following beetroot juice supplementation do not differ between recreational,competitive and elite sprint athletes

Purpose: There is an ongoing debate whether highly trained athletes are less responsive to the ergogenic properties of nitrate. We assessed the effects of nitrate supplementation on plasma nitrate and nitrite concentrations and repeated-sprint performance in recreational, competitive and elite sprint athletes. Methods: In a randomized double-blinded cross-over design, recreational cyclists (n?=?20), national talent speed-skaters (n?=?22) and Olympic-level track cyclists (n?=?10) underwent two 6-day supplementation periods; 140?mL/d nitrate-rich (BR; ～800?mg/d) and nitrate-depleted (PLA; ～0.5?mg/d) beetroot juice. Blood samples were collected and three 30-s Wingate tests were performed. Results: Plasma nitrate and nitrite concentrations were higher following BR vs PLA (P?P?>?.10). Peak power over the three Wingates was not different between BR and PLA (1338?±?30 vs 1333?±?30 W; P?=?.62), and there was no interaction between treatment (BR-PLA) and Wingate number (1-2-3; P?=?.48). Likewise, mean power did not differ between BR and PLA (P?=?.86). In contrast, time to peak power improved by ～2.8% following BR vs PLA (P?=?.007). This improvement in BR vs PLA was not different between Wingate 1, 2 and 3. Moreover, the effects of BR vs PLA did not differ between sport levels for any Wingate parameter (all P?>?.30). Conclusion: The plasma and repeated-sprint performance responses to beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes. Beetroot juice supplementation reduces time to reach peak power, which may improve the capacity to accelerate during high-intensity and sprint tasks in recreational as well as elite athletes.     

Commercially available compression garments or electrical stimulation do not enhance recovery following a sprint competition in elite cross-country skiers

This study investigated whether commercially available compression garments (COMP) exerting a moderate level of pressure and/or neuromuscular electrical stimulation (NMES) accelerate recovery following a cross-country sprint skiing competition compared with a control group (CON) consisting of active recovery only. Twenty-one senior (12 males, 9 females) and 11 junior (6 males, 5 females) Swedish national team skiers performed an outdoor sprint skiing competition involving four sprints lasting ～3–4 min. Before the competition, skiers were matched by sex and skiing level (senior versus junior) and randomly assigned to COMP (n?=?11), NMES (n?=?11) or CON (n?=?10). Creatine kinase (CK), urea, countermovement jump (CMJ) height, and perceived muscle pain were measured before and 8, 20, 44 and 68?h after competition. Neither COMP nor NMES promoted the recovery of blood biomarkers, CMJ or perceived pain post-competition compared with CON (all P?>?.05). When grouping all 32 participants, urea and perceived muscle pain increased from baseline, peaking at 8?h (standardised mean difference (SMD), [95% confidence intervals (CIs)]): 2.8 [2.3, 3.2]) and 44?h (odds ratio [95% CI]: 3.3 [2.1, 5.1]) post-competition, respectively. Additionally, CMJ was lower than baseline 44 and 68?h post-competition in both males and females (P?相似文献   

The effect of resisted sprint training on maximum sprint kinetics and kinematics in youth

Abstract

Resisted sled towing is a popular and efficient training method to improve sprint performance in adults, however, has not been utilised in youth populations. The purpose therefore was to investigate the effect of resisted sled towing training on the kinematics and kinetics of maximal sprint velocity in youth of different maturation status. Pre- and post-intervention 30 metre sprint performance of 32 children, 18 pre-peak height velocity (PHV) and 14 mid-/post-PHV, were tested on a non-motorised treadmill. The 6-week intervention consisted of ～12 sessions for pre-PHV and 14 for mid-/post-PHV of resisted sled towing training with each sessions comprised of 8–10 sprints covering 15–30 metres with a load of 2.5, 5, 7.5 or 10% body mass. Pre-PHV participants did not improve sprint performance, while the mid-/post-PHV participants had significant (P < 0.05) reductions (percent change, effect size) in sprint time (?5.76, ?0.74), relative leg stiffness (?45.0, ?2.16) and relative vertical stiffness (?17.4, ?0.76) and a significant increase in average velocity (5.99, 0.76), average step rate (5.65, 0.53), average power (6.36, 0.31), peak horizontal force (9.70, 0.72), average relative vertical forces (3.45, 1.70) and vertical displacement (14.6, 1.46). It seems that sled towing may be a more suitable training method in mid-/post-PHV athletes to improve 30 metre sprint performance.     

Kinematic differences between front crawl sprint and distance swimmers at sprint pace

The purpose of this study was to use three-dimensional methods to determine whether there are distinct kinematic differences between sprint and distance front crawl swimmers when swimming at a sprint pace. Seven sprint and eight distance specialists performed four 25-m sprints through a 6.75-m(3) calibrated space recorded by six gen-locked cameras. The variables of interest were: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, shoulder and hip roll angles, duration of stroke phases, and the time corresponding to particular events within the stroke cycle relative to hand entry. Differences between sprint and distance swimmers were assessed with an independent t-test for each variable, in addition to effect size calculations. Differences between sprint and distance front crawl swimmers were generally small and not significant when swimming at a sprint pace. Differences were limited to temporal aspects of the stroke cycle. These findings suggest that coaches should not train sprint and distance specialists differently in terms of technique development.     

短跑运动的摆动和转动技术与运动实践

从“快速摆动“技术产生的过程,运动生物力学原理,在运动实践中的功效进行分析,以期加深教练员与运动员对此技术的理解.