Eleni Bassa

The effect of chronological age and gender on the development of sprint performance during childhood and puberty.

Papaiakovou, G, Giannakos, A, Michailidis, C, Patikas, D, Bassa, E, Kalopisis, V, Anthrakidis, N, and Kotzamanidis, C. The effect of chronological ageand gender on the development of sprint performance during childhood and puberty. J Strength Cond Res 23(9): 2568-2573, 2009-The purpose of the present study was to examine the effect of chronological age and gender on speed development during different sprinting phases in children and adolescents of both genders. The sample consisted of 360 sedentary pupils aged between 7 and 18 years, with 15 pupils representing each subgroup. The 30-m sprint speed was measured with photocells every 10 m. According to the results, boys and girls showed a gradual improvement in running speed during each sprint phase. The 18-year-old boys had significantly higher sprint speed in all measured distances compared to the 15-year-old or younger boys (p < 0.05), whereas the 18-year-old girls had significantly higher speed at the distances of 0 to 10, 10 to 20, 20 to 30, and 0 to 30 m compared to the 13- and 12-year-old or younger girls (p < 0.05). Significant differences between genders in the 15-years-old or older participants were observed. It is concluded that, from 7 to 18 years of age, gender and chronological age are factors that affect running speed during the 30-m sprint. Furthermore, the performance on each sprint phase is uniformly affected by the chronological age. Boys run faster than girls in all running phases, and the span between genders increases after the age of 15 years. It is useful that coaches take these findings into consideration when evaluating children in sprint performance.

The effect of sprinting after each set of heavy resistance training on the running speed and jumping performance of young basketball players.

Tsimahidis, K, Galazoulas, C, Skoufas, D, Papaiakovou, G, Bassa, E, Patikas, D, and Kotzamanidis, C. The effect of sprinting after each set of heavy resistance training on the running speed and jumping performance of young basketball players. J Strength Cond Res 24(8): 2102-2108, 2010-The purpose of this study was to investigate the effect of a 10-week heavy resistance combined with a running training program on the strength, running speed (RS), and vertical jump performance of young basketball players. Twenty-six junior basketball players were equally divided in 2 groups. The control (CON) group performed only technical preparation and the group that followed the combined training program (CTP) performed additionally 5 sets of 8-5 repetition maximum (RM) half squat with 1 30-m sprint after each set. The evaluation took place before training and after the 5th and 10th weeks of training. Apart from the 1RM half squat test, the 10- and 30-m running time was measured using photocells and the jump height (squat, countermovement jump, and drop jump) was estimated taking into account the flight time. The 1RM increased by 30.3 ± 1.5% at the 10th week of training for the CTP group (p < 0.05), whereas the CON group showed no significant increase (1.1 ± 1.6%, p > 0.05). In general, all measured parameters showed a statistically significant increase after the 5th and 10th weeks (p < 0.05), in contrast to the CON group (p > 0.05). This suggests that the applied CTP is beneficial for the strength, RS, and jump height of young basketball players. The observed adaptations in the CTP group could be attributed to learning factors and to a more optimal transfer of the strength gain to running and jumping performance.

Submaximal Fatigue and Recovery in Boys and Men

We examined the effects of a sustained submaximal isometric contraction on fatigue and recovery rates in untrained prepubescent boys and men. Fifteen prepubescent boys and 15 men executed an isometric plantar flexion at 20% of their maximal voluntary contraction for 10 min. During the fatigue protocol, surface electromyogram of the soleus, medial gastrocnemius, and tibialis anterior muscles were obtained. Following the fatigue protocol, maximal voluntary contraction data were also obtained every 3 min throughout a 15-min recovery period. During the fatigue protocol, agonist and antagonist surface electromyogram increased gradually to a similar extent in both groups. Following fatigue, torque and surface electromyogram during a maximal voluntary contraction decreased compared to pre-fatigue values and recovered in a similar manner in both groups. However, boys showed faster recovery in torque and surface electromyogram during the third minute of recovery period. It is concluded that a low-intensity sustained isometric fatigue protocol induces similar fatigue levels in boys and men. However, there is evidence that boys can recover faster than men.

The Effect of Basketball Training on the Muscle Strength of Adults With Mental Retardation

Tsimaras, VK, Samara, CA, Kotzamanidou, MC, Bassa, EI, Fotiadou, EG, and Kotzamanidis, CM. The effect of basketball training on the muscle strength of adults with mental retardation. J Strength Cond Res 23(9): 2638-2644, 2009-The purpose of this study was to evaluate the effect of basketball training on the muscle strength of adults with mental retardation (MR). Twenty-four adults with and without MR were separated into 3 groups. Eight adults (mean age 25.4 years) with normal IQ constituted the control group (NIQ). Eight adults (mean age 26.5 years) with MR and all participating in a 4-year systematic basketball exercise program constituted the trained group (MR-T), and 8 adults (mean age 25.3 years) with MR exercised occasionally for recreational reasons formed the MR-R group. Parameters measured were isometric and isokinetic concentric and eccentric muscle strength. All subjects performed a leg strength test on a Cybex Norm isokinetic dynamometer. Analysis of variance was used to examine mean differences between the values of the 3 groups. A significance level of 0.05 was used for all tests. The NIQ group showed a statistically significant difference in all measured values compared to the MR groups. The MR-T group presented higher absolute and relative torque scores for both knee extensors and flexors than the MR-R group, whereas the MR-R group presented statistically higher antagonistic activity for both knee extensors and flexors than the MR-T group. In addition, both MR groups presented statistically higher antagonistic activity for both knee extensors and flexors compared to the NIQ group. Data support participation on a systematic and well-designed basketball training program to improve muscle strength levels of adults with MR. Participation in basketball without necessarily focusing on developing specific fitness components may be an effective training strategy for the promotion of strength of adults with MR.

Central and Peripheral Fatigability in Boys and Men during Maximal Contraction

PURPOSE The purpose of this study was to examine central and peripheral factors of fatigability that could explain the differences in fatigability between adults and prepubertal boys after maximal sustained isometric contraction. METHODS A total of 11 untrained adult men and 10 prepubescent boys volunteered to participate in this study. The level of voluntary activation was assessed before and after fatigue by means of the twitch interpolation technique as well as peak twitch torque, maximum rate of torque development and maximum M-wave (Mmax) area of the soleus and medial gastrocnemius. The fatigue-inducing protocol consisted of a sustained maximal voluntary contraction (MVC) of the ankles plantar flexor at 100% of MVC until the task could no longer be sustained at 50% of MVC. RESULTS During the fatigue-inducing protocol, boys were fatigued less, showing longer endurance limit and delayed torque and agonist EMG decrease. After fatigue, the level of activation decreased to a similar extent in both groups, and boys were less affected regarding their peak twitch torque and rate of torque development, whereas no differentiation between the groups was observed regarding the decrease in Mmax area of the examined muscles. CONCLUSIONS The results obtained provide evidence that the greater fatigability resistance in prepubertal children during sustained maximal contractions is mainly explained by peripheral rather than central factors.

POST-ACTIVATION POTENTIATION: THE NEURAL EFFECTS OF POST—ACTIVATION DEPRESSION

Introduction: Our knowledge of the neurophysiology of post‐activation potentiation (PAP) is limited. The purpose of this study was to examine the effect of PAP on twitch torque and H‐reflex amplitude after a 10‐s maximal voluntary contraction (MVC). Methods: PAP measurements were assessed with the plantarflexors in a relaxed state and during a tonic contraction at 10% MVC. Results: The H‐reflex/maximum M‐wave ratio (H/M) decreased significantly (P < 0.05) and returned to baseline levels after 1 min. The decrement in H/M was depressed when the plantarflexors were active at 10% MVC, and the depression was more obvious in the lateral gastrocnemius than in the soleus muscle. Conclusions: The inhibition induced immediately after contraction could be attributed to post‐activation depression. We conclude that PAP after a 10‐s MVC cannot be attributed to increased motor neuron excitability through the reflex pathway as assessed by the H‐reflex technique. Muscle Nerve 52: 252–259, 2015

The post-activation potentiation effect on sprint performance after combined resistance/sprint training in junior basketball players

Abstract The aim of this study was to examine the effect of a 10-week combined resistance/sprint training programme in the post-activation potentiation of sprint performance before, between and after resistance training sets. Twenty-six junior basketball players were randomly divided into a control and a combined training group. The combined training group performed a combined training programme consisting of 5 sets at 5–8 RM (Repetition Maximum) half-squats with sprints performed between each set. Post-activation potentiation was considered as the increase in sprint velocity in trials executed between and after the resistance sets compared with the sprint trial performed before the resistance sets of the respective first and last training session. For sprint evaluation the running distances 0–10 and 0–30 m were selected. The intervention increased both strength and sprint performance. No post-activation potentiation effect was observed during the first training session in either group. Post-activation potentiation appeared in the combined training group during the last training session of the intervention in both 0–10 and 0–30 m sprint. This study illustrates that post-activation potentiation effect on sprint performance in junior basketball players, who did not previously follow systematic resistance training, emerges after a 10-week resistance/sprint combined training programme.

The Effect of Dropping Height on Jumping Performance in Trained and Untrained Prepubertal Boys and Girls

Abstract Bassa, E, Patikas, D, Panagiotidou, A, Papadopoulou, S, Pylianidis, T, and Kotzamanidis, C. The effect of dropping height on jumping performance in trained and untrained prepubertal boys and girls. J Strength Cond Res 26(8): 2258–2264, 2012—Plyometric training in children, including different types of jumps, has become common practice during the last few years in different sports, although there is limited information about the adaptability of children with respect to different loads and the differences in performance between various jump types. The purpose of this study was to examine the effect of gender and training background on the optimal drop jump height of 9- to 11-year-old children. Sixty prepubertal (untrained and track and field athletes, boys and girls, equally distributed in each group [n = 15]), performed the following in random order: 3 squat jumps, 3 countermovement jumps (CMJs) and 3 drop jumps from heights of 10, 20, 30, 40, and 50 cm. The trial with the best performance in jump height of each test was used for further analysis. The jump type significantly affected the jump height. The jump height during the CMJ was the highest among all other jump types, resulting in advanced performance for both trained and untrained prepubertal boys and girls. However, increasing the dropping height did not change the jumping height or contact time during the drop jump. This possibly indicates an inability of prepubertal children to use their stored elastic energy to increase jumping height during drop jumps, irrespective of their gender or training status. This indicates that children, independent of gender and training status, have no performance gain during drop jumps from heights up to 50 cm, and therefore, it is recommended that only low drop jump heights be included in plyometric training to limit the probability of sustaining injuries.

The acute effects of an intense stretch-shortening cycle fatigue protocol on the neuromechanical parameters of lower limbs in men and prepubescent boys

ABSTRACT The study examined the differences between boys and adults after an intense stretch-shortening cycle fatigue protocol on neuromechanical parameters of the lower limb. Thirteen boys (9–11 years old) and 13 adult men (22–28 years old) were tested for maximal isometric voluntary knee extension torque and drop jump (DJ) performance from 30 cm before and immediately after a fatigue protocol, consisted of 10 × 10 maximum effort vertical jumps. Three-dimensional kinematics, kinetics and electromyographic (EMG) parameters of the lower extremities muscles were recorded during DJs before and after the fatigue test. The results indicated that reduction in maximal isometric torque and jumping performance was significantly higher in adults compared to boys. Vertical ground reaction forces, contact time and maximum knee flexion increased in a greater extend in adults than in boys. In addition, preactivation, EMG agonist activity, knee joint stiffness and stretch reflex decreased more in adults than in boys at all the examined phases of jumping tasks. It is concluded that employed fatigue protocol induced acute reduction in performance and altered motor control during jumping in both age groups. However, the differences in the level of fatigue between the 2 groups could be attributed to neuromuscular, mechanical and kinematic parameters observed between groups.

WARM-UP PROTOCOLS FOR HIGH SCHOOL STUDENTS.

The study compared the acute effects of three warm-up protocols on change-of-direction speed, reaction time, and movement time of upper extremities. Participants were 27 Greek high school students from an urban area (M age = 17.2 yr., SD = 0.2, range = 16.5 −18.0). All participants performed the following warm-up protocols on three different days: (a) 3 min. jogging followed by 5 min. static stretching, (b) 3 min. jogging followed by 5 min. dynamic stretching, and (c) 3 min. jogging followed by 5 min. of rest without stretching. At the end of each protocol, participants performed sprints of moderate to submaximal intensity. After the warm-up protocols, participants performed the following tests: “505-change-of-direction-speed,” reaction time, and movement time (arm movements). There was no significant effect of protocols on the performance tests. Pre-exercise stretching may not be required for performance improvement in activities involving change-of-direction speed, reaction, and movement time if the final part of the warm-up involves sprinting. The advantage of a short duration warm-up is that it offers students more time to play in physical education lessons. However, it is generally important for students to learn the benefits of stretching and how to stretch for lifelong fitness.