Success to Clear the Bar in Elite Pole Vaulters is Affected by Step Frequency Perturbation.

The purpose of the study was to identify the interaction of step characteristics, along with the direction and magnitude of their asymmetry of elite male and female pole vaulters between successful and failed attempts. It was hypothesized that step characteristics and the magnitude of asymmetry between the two legs would interact with the outcome of the attempt. The approach runs of 12 pole vaulters (7 males, 5 females) were recorded during an indoor international competition. The leg used by the athlete for taking-off was defined as the non-pole-carrying leg, while the other was the pole-carrying leg. Using spatiotemporal information obtained from recordings with a panning camera (300 fps), the last steps of each athlete's approach run were analyzed for length, frequency, average velocity, and inter-limb asymmetry. There was no inter-limb difference (p > 0.05) in the absolute values of step length or step velocity between successful and failed attempts. However, the pole-carrying leg presented significantly (p < 0.05) higher step frequency values at the failed attempts. There was no significant difference (p > 0.05) in asymmetry values for step length, frequency, and average velocity between successful and failed attempts. Although step velocity remained unaffected, failed attempts were characterized by a perturbation in the interaction of step frequency and step length. The present findings suggest that although high velocity at the final phase of the approach is essential, it is not the sole determining factor for a successful attempt.

Pivot Step Jump: A New Test for Evaluating Jumping Ability in Young Basketball Players.

Jumping ability in basketball is usually assessed using standardized vertical jump tests. However, they lack specificity and do not consider the player's basketball skills. Several studies have suggested performing specific jump tests, which are tailored to the movement patterns and requirements of a basketball game. The pivot step jump test (PSJT) is a novel test designed to evaluate the specific jumping abilities of basketball players by combining a pivot step on one leg with a maximum bilateral vertical jump. This study had two aims: to determine the reliability and validity of the PSJT using typical jump tests as the criterion measure and to demonstrate the PSJT as a practical test to evaluate specific jumping ability in young male and female basketball players. Twenty female (EGA; 14.0 ± 0.7 years, 59.3 ± 7.9 kg, 162.1 ± 5.5 cm) and fifteen male (EGB; 14.0 ± 0.7 years, 58.1 ± 7.7 kg, 170.3 ± 6.4 cm) basketball players participated in the study. The test−retest reliability of the PSJT within sessions (intrasession reliability) and across sessions (intersession reliability) was assessed within EGA. For the evaluation of validity, EGB performed the PSJT and a series of criterion jumping tests. For EGA, no changes (p > 0.05) were found in PSJT performance between test sessions and excellent intra- and intersession reliability was observed (ICCs > 0.75). Correlation coefficients indicated high factorial validity between the jumping tests and PSJT (r = 0.71−0.91, p < 0.001). The PSJT appears to offer a valid assessment of jumping ability in basketball and is a practical test for assessing sport-specific jumping skills in young basketball players.

The influence of a hurdle target point on the kinematics of the handspring vault approach run during training.

The aim of this study was to investigate if a visible target for the hurdle take-off would influence the onset of visual regulation and hurdle kinematics during the approach run. Ten elite male gymnasts (age 23.4 ± 4.9 years, height 1.68 ± 0.06 m, mass 63.3 ± 6.2 kg) performed six handspring vaults with a full approach run under two controlled conditions: (a) with a 5-cm white tape on the runway marking the last touchdown of the approach run and the commencement of the hurdle (tape condition-T) and (b) under the standard vaulting regulations (non-tape condition-NT). Spatiotemporal data of the approach run and the hurdle were collected by four stationary and one panning cameras (sampling rate 300 fps). Eight out of 10 gymnasts commenced regulation earlier under T than under NT. Under T condition, horizontal velocity (Vx to = 9.06 ± 0.41 m/s) and vertical velocity (V to = 9.35 ± 0.37 m/s) was significantly faster than under NT condition (Vx to = 8.85 ± 0.49 m/s; V to = 9.11 ± 0.47 m/s). Introducing a target for the hurdle facilitates an early onset of step regulation and significantly improves the kinematics of the hurdle.

Step characteristic interaction and asymmetry during the approach phase in long jump.

The aim of this study was to investigate the relative influence of step length (SL) and step frequency (SF) on step velocity (SV) during the approach run of high-level long jumpers and to quantify the asymmetry of these step characteristics. Spatiotemporal data of the approach run were collected during national competition from 10 long jumpers (age 26.2 ± 4.1 years, height 1.84 ± 0.06 m, mass 72.77 ± 3.23 kg, personal best performance 7.96 ± 0.30 m). Analyses were conducted for total approach, early approach and late approach. For the total approach 4/10 athletes were SF reliant and 6/10 athletes favoured neither characteristic. At the early approach, 3/10 athletes were SF reliant and 7/10 athletes favoured neither. During late approach 2/10 athletes demonstrated SL reliance, 7/10 athletes were SF reliant and 1/10 athletes favoured neither. Four athletes displayed significant asymmetry for SL and three for SF. However, no athletes demonstrated significant asymmetry for SV indicating that the asymmetrical demands of take-off do not have a marked influence on step characteristic asymmetry, probably due to the constraints of the event. Consideration should be given to the potentially conflicting demands between limbs for individual athletes.

Effects of static and dynamic stretching on sprint and jump performance in boys and girls.

The aim of this study was to investigate the acute effects of static (SS) and dynamic stretching (DS) on explosive power, flexibility, and sprinting ability of adolescent boys and girls and to report possible gender interactions. Forty-seven active adolescent boys and girls were randomly tested after SS and DS of 40 seconds on quadriceps, hamstrings, hip extensors, and plantar flexors; no stretching was performed at the control condition. Pretreatment and posttreatment tests examined the effects of stretching on 20-m sprint run (20 m), countermovement jump (CMJ) height, and sit and reach flexibility test. In terms of performance, SS hindered 20 m and CMJ in boys and girls by 2.5 and 6.3%, respectively. Dynamic stretching had no effect on 20 m in boys and girls but impaired CMJ by 2.2%. In terms of flexibility, both SS and DS improved performance with SS being more beneficial (12.1%) compared with DS (6.5%). No gender interaction was found. It can therefore be concluded that SS significantly negates sprinting performance and explosive power in adolescent boys and girls, whereas DS deteriorates explosive power and has no effect on sprinting performance. This diversity of effects denotes that the mode of stretching used in adolescent boys and girls should be task specific.

Effects of acute creatine loading with or without carbohydrate on repeated bouts of maximal swimming in high-performance swimmers.

The addition of carbohydrate (CHO) to an acute creatine (Cr) loading regimen has been shown to increase muscle total creatine content significantly beyond that achieved through creatine loading alone. However, the potential ergogenic effects of combined Cr and CHO loading have not been assessed. The purpose of this study was to compare swimming performance, assessed as mean swimming velocity over repeated maximal intervals, in high-performance swimmers before and after an acute loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO). Ten swimmers (mean +/- SD of age and body mass: 17.8 +/- 1.8 years and 72.3 +/- 6.8 kg, respectively) of international caliber were recruited and were randomized to 1 of 2 groups. Each swimmer ingested five 5 g doses of creatine for 4 days, with the Cr + CHO group also ingesting approximately 100 g of simple CHO 30 minutes after each dose of creatine. Performance was measured on 5 separate occasions: twice at "baseline" (prior to intervention, to assess the repeatability of the performance test), within 48 hours after intervention, and then 2 and 4 weeks later. All subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups. In addition, all swimmers continued to produce faster swim times for up to 4 weeks after intervention. Our findings suggest that no performance advantage was gained from the addition of carbohydrate to a creatine-loading regimen in these high-caliber swimmers.