Apostolos Theodorou

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

Abstract Paradisis, GP, Pappas, PT, Theodorou, AS, Zacharogiannis, EG, Skordilis, EK, and Smirniotou, AS. Effects of static and dynamic stretching on sprint and jump performance in boys and girls. J Strength Cond Res 28(1): 154–160, 2014—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.

The time-frame of acute resistance exercise effects on football skill performance: The impact of exercise intensity

Abstract The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8–10 repetitions/set, 65–70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4–6 repetitions/set, 85–90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.

Evaluating the Approach Run of Class F11 Visually Impaired Athletes in Triple and Long Jumps

The present study examined stride pattern characteristics of Class F11 visually impaired long jumpers and triple jumpers. Athletes demonstrated initial ascending footfall variability followed by descending variability, on the second (long jumpers) and third (triple jumpers) stride prior to take-off, at a mean distance of 6.26 m (long jumpers) and 7.36 m (triple jumpers) from the take-off board. Toe-board-distance variability reached a maximum value of 0.36 m and 0.38 m for the long and triple jump, respectively. Last stride toe-board-distance variability was 0.29 m (long jump) and 0.25 m (triple jump). Class F11 visually impaired athletes exhibit regulation of goal-directed gait analogous to that of non-visually impaired athletes.

Locomotor control in the long jump approach run in young novice athletes

Abstract We examine the presence of visually regulated control in young, novice long jumpers as they approach the takeoff board. The approach run of 27 novice jumpers (age 12–13 years) practising jump training for a short period was video-recorded during competition. Findings revealed that young, novice participants adjust the length of the final steps of their approach run, suggesting the presence of visual control. Step regulation commenced on the fifth and fourth step from the board for boys and girls respectively. Their pattern of footfall variability was found to be comparable to that of skilled long jumpers, although young, novice participants presented slightly higher variability. It appears that even a limited period of jump training may contribute to a more consistent run-up as well as to smaller takeoff error, offsetting the limitations imposed by the partially developed cognitive abilities and perceptual awareness of young athletes.

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

ABSTRACT 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.

Performance environment and nested task constraints influence long jump approach run: a preliminary study

ABSTRACT The purpose of the study was to investigate possible changes at step pattern and technical performance of the long jump approach run in seven young long jumpers by modifying the performance environment (long jump runway versus track lane) and the nested actions (run-through with take-off versus complete long jump). Our findings suggest that the step pattern and technical aspects of the approach run are affected by environmental context and nested task constraints. In terms of environmental context, it appears that practising the training routine of run-through followed by take-off on the long jump runway allows athletes to simulate competition conditions in terms of step regulation and technical efficacy. The task of run-through followed by take-off on the track lane failed to initiate visual perception, step regulation and technical efficiency at the steps preceding the instant of take-off. In terms of nested task constraints, when run-ups were followed by jump for distance instead of only a take-off, a higher level of consistency was achieved and step regulation was based on perception–action coupling. Practising long jump run-up accuracy at a setting not containing the informational elements of the performance environment fails to develop the key elements of the skill.

Influence of visual impairment level on the regulatory mechanism used during the approach phase of a long jump.

The purpose of the study was to investigate the occurrence of stride regulation at the approach phase of the long jump in athletes with normal vision and visually deprived Class F12 and F13 athletes. All the athletes exhibited the presence of a regulatory mechanism. In the normal vision group this occurred on the fifth-to-last stride. In Class F12 athletes regulation commenced on the fourth-to-last stride for males and third-to-last stride for females. Class F13 males commenced regulation, like the control group, on the fifth-to-last stride; but females commenced on the fourth-to-last stride. The study demonstrated that reduced vision does not prevent Class F12 and F13 athletes from applying a regulatory mechanism similar to that observed in sighted athletes. However, the control mechanism of regulation emerged earlier in non-visually deprived long jumpers and the least visually impaired Class F13 athletes, signifying the importance of visual function in the regulatory stimuli.

The effect of combined supplementation of carbohydrates and creatine on anaerobic performance.

The purpose of the study was to examine the effect of creatine (Cr) supplementation on anaerobic performance when ingesting creatine and carbohydrates (CHO) together. Twenty male physical education students comprised the two experimental (CR and CRCHO) and one control (CON) groups of the study. All groups performed three 30 s anaerobic Wingate tests (AWTs) interspersed with 6 minutes of recovery. The CR group (n = 7) ingested 5 g of Cr 5 times per day for 4 days. Subjects in the CRCHO group (n = 6) ingested the same quantity but additionally after each 5 g dose of Cr consumed 500 ml of a commercially available energy drink containing 100 g of simple sugars. Over all three AWTs average mean power improved significantly compared to baseline for the CR group (5.51%) but not for the CRCHO group (3.06%). Mean power for the second AWT was improved following the acute loading for the CR group only (4.54%) and for the third AWT for both CR (8.49%) and CRCHO (5.75%) groups. Over all three AWTs a significant change was recorded in average peak power following the acute loading for the CR group (8.26%) but not for the CRCHO group (4.11%). Peak power was significantly improved following the loading only for the CR group during the third AWT (19.79%). No changes in AWT performance were recorded for the CON group after intervention. The findings of the present study suggest that ingesting creatine together with carbohydrates will not further improve performance compared to the ingestion of creatine only.

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

ABSTRACT 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.

Consequences of the European Team Championships’ new rules on Pole Vault

Over the 2009 European Team Championship, the European Athletics Association proceeded to a modification of Pole Vault rules according to which, each competitor was entitled to a maximum of 4 aggregate fouls throughout the competition. The purpose of the study was to examine the effects of new rules implementation on men’s and women’s Pole Vault competition. The 2008 and 2009 European Team Championships results for the Super and First Leagues (n = 48; 24 males & 24 females) were compared. The dependent variables were: Athlete’s Final Height (AFH), Number of Efforts (NE), Successful Efforts (SE), Failed Efforts (FE) and Efforts Forgoed (EF). Men’s AFH remained unchanged (0.04%). NE reduced by 1.92% while the percentile SE/FE distribution changed favourably towards the SE (40.65%/59.35% for 2008 vs 43.42%/56.58% for 2009). Women’s AFH remained unchanged (+ 0.24%). NE decreased significantly by 16.28%, while the percentile SE/FE distribution changed favourably towards the SE (44.70%/55.30% for 2008 vs 47.21%/52.79% for 2009). Overall, the restriction in Pole Vault efforts seems to have had a slightly positive effect on men’s and women’s performance.