This study aimed to describe training characteristics as well as physical, technical and morphological changes of an elite Olympic swimming sprinter throughout his road to 21 s in the 50 m freestyle. Over a ∼2.5-year period, the following assessments were obtained: external training load, competitive performance, instantaneous swimming speed, tethered force, dry-land maximal dynamic strength in bench press, pull-up and back squat and body composition. From 2014 to 2016, the athlete dropped 3.3% of his initial best time by reducing total swimming time (i.e. the total time minus 15-m start time – from 17.07 s to 16.21 s) and improving the stroke length (from 1.83 m to 2.00 m). Dry-land strength (bench press: 27.3%, pull-up: 9.1% and back squat: 37.5%) and tethered force (impulse: 30.5%) increased. Competitive performance was associated to average (r = −0.82, p = 0.001) and peak speeds (r = −0.71; p = 0.009) and to lean body mass (r = −0.55; p = 0.03), which increased in the first year and remained stable thereafter. External training load presented a polarized pattern in all training seasons. This swimmer reached the sub-22 s mark by reducing total swimming time, which was effected by a longer stroke length. He also considerably improved his dry-land strength and tethered force levels likely due to a combination of neural and morphological adaptations.

Background Individuals with cerebral palsy (CP) have problems in everyday tasks such as walking and climbing stairs due to a combination of neuromuscular impairments such as spasticity, muscle weakness, reduced joint flexibility and poor coordination. Development of evidence-based interventions are in pivotal role in the development of better targeted rehabilitation of CP, and thus in maintaining their motor function and wellbeing. Our aim is to investigate the efficacy of an individually tailored, multifaceted exercise intervention (EXECP) in children and young adults with CP. EXECP is composed of strength, flexibility and gait training. Furthermore, this study aims to verify the short-term retention of the adaptations three months after the end of the EXECP intervention. Methods Twenty-four children and young adults with spastic CP will be recruited to participate in a 9-month research project with a 3-month training intervention, consisting of two to three 90-min sessions per week. In each session, strength training for the lower limbs and trunk muscles, flexibility training for the lower limbs and inclined treadmill gait training will be performed. We will evaluate muscle strength, joint flexibility, neuromuscular and cardiometabolic parameters. A nonconcurrent multiple baseline design with two pre-tests and two post-tests all interspaced by three months is used. In addition to the CP participants, 24 typically developing age and sex-matched participants will perform the two pre-tests (i.e. no intervention) to provide normative data. Discussion This study has a comprehensive approach examining longitudinal effects of wide variety of variables ranging from physical activity and gross motor function to sensorimotor functions of the brain and neuromuscular and cardiometabolic parameters, providing novel information about the adaptation mechanisms in cerebral palsy. To the best of our knowledge, this is the first intervention study providing supervised combined strength, flexibility and gait training for young individuals with CP. Trial registration number ISRCTN69044459, prospectively registered (21/04/2017).

Valadão, Pedro Frederico, 2012. Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics. Department of Biology of Physical Activity, University of Jyväskylä. Master's Thesis in Biomechanics. 105 pp.The present study was designed to investigate corticospinal excitability modulation during maximum isometric and eccentric muscle actions with two different velocities. Moreover, the study aimed to clarify the effect of muscle action type on muscle-tendon mechanical behavior in order to shed light into the possible role of sensory information in modulating corticospinal excitability during different muscle actions. We compared motor evoked potentials (MEPs) to transcranial magnetic stimulation and Hoffman reflexes (H-reflex) in soleus muscle during isometric, slow eccentric (25 deg/s) and fast eccentric (100 deg/s) muscle actions. Concomitantly, ultrasonography was utilized to access soleus and medial gastrocnemius fascicle behavior, characterized by fascicle length, velocity and pennation angle.The main finding was that soleus H-reflex was depressed (P < 0.001) during both fast and slow eccentric protocols as compared to isometric, while no differences in fascicle length (P = 0.569) and pennation angle (P = 0.293) were found among the three protocols.Furthermore, although the fast eccentric protocol had a greater fascicle velocity than slow eccentric (P < 0.05), there were no differences in H-reflex (P > 0.05). No differences in MEP sizes were found among the three protocols (P = 0.750), while absolute silent period was significantly shorter (P = 0.009) for both eccentric protocols as compared to isometric.Taken together, the present results corroborates with the idea that the central nervous system has an unique activation strategy during eccentric muscle actions , Enoka 1996, and further refutes the hypothesis that sensory information plays an important role in modulating these actions.

Hyper-resistance is an increased resistance to passive muscle stretch, a common feature in neurological disorders. Stretch hyperreflexia, an exaggerated stretch reflex response, is the neural velocity-dependent component of hyper-resistance, and has been quantitatively measured using the stretch reflex threshold (i.e., joint angle at the stretch reflex electromyographic onset). In this study, we introduce a correction in how the stretch reflex threshold is calculated, by accounting for the stretch reflex latency (i.e., time between the stretch reflex onset at the muscle spindles and its appearance in the electromyographic signal). Furthermore, we evaluated how this correction affects the stretch reflex threshold in children and young adults with spastic cerebral palsy. A motor-driven ankle dynamometer induced passive ankle dorsiflexions at four incremental velocities in 13 children with cerebral palsy (mean age: 13.5 years, eight males). The stretch reflex threshold for soleus and medial gastrocnemius muscles was calculated as 1) the joint angle corresponding to the stretch reflex electromyographic onset (i.e., original method); and as 2) the joint angle corresponding to the electromyographic onset minus the individual Hoffmann-reflex latency (i.e., latency corrected method). The group linear regression slopes between stretch velocity and stretch reflex threshold differed in both muscles between methods (p &lt; 0.05). While the original stretch reflex threshold was velocity dependent in both muscles (p &lt; 0.05), the latency correction rendered it velocity independent. Thus, the effects of latency correction on the stretch reflex threshold are substantial, especially at higher stretch velocities, and should be considered in future studies.

OBJETIVO: Propor um método de familiarização individualizado para saltos verticais e verificar o seu efeito na variabilidade intrassujeito. MÉTODOS: Cinquenta e três homes (média ± DP; idade 23,5 ± 3,3 anos; estatura 1,76 ± 0,08 m; massa 72,8 ± 8,6 kg; percentual de gordura 12,9 ± 5,2%) realizaram sucessivos saltos até atingir o nível de estabilidade proposto. Após 48 h este processo era repetido e a estabilidade entre dias era verificada, se necessário, mais sessões eram realizadas. O nível de estabilidade foi determinado por um teste z, com intervalo de confiança de 95%. Após o processo de familiarização, duas sessões experimentais adicionais foram realizadas para determinar a confiabilidade do desempenho no salto agachado (SA) e no salto com contramovimento (SCM). O coeficiente de variação e o erro padrão de medida foram determinados individualmente (CVi e EPMi). Um teste t pareado foi realizado para verificar diferenças no CVi e EPMi antes e depois do processo de familiarização. RESULTADOS: O CVi apresentou uma redução significativa após o processo de familiarização (p < 0,001), alterando de 5,01 ± 2,40% para 2,95 ± 0,89% no SA e de 4,50 ± 2,19% para 2,58 ± 0,81% no SCM. O mesmo ocorreu para o EPMi variando de 1,29± 0,53 cm para 0,83 ± 0,25 cm no SA e de 1,35 ± 0,51 cm para 0,83 ± 0,26 cm no SCM. CONCLUSÃO: o método de familiarização individualizado proposto reduziu significativamente a variação intrassujeito, permitindo maior poder estatístico em estudos experimentais e maior sensibilidade para ferramentas de monitoramento do desempenho.