Development of Muscle Function in Prepubertal Children As a Response to Growth and Resistance Training

Официальное название

Muscle Growth and Development of Neuromuscular Capacities in Prepubertal Children - a Randomized Controlled Intervention Study

Обзор

Healthy skeletal muscle development is crucial for a life-long quality of life. Childhood and puberty may be key periods for developing muscle growth and neuromuscular capacities, which are essential for bone-muscle interaction, metabolism, and participation in various sports. Even though the central role of physical activity in healthy physical development is well recognized, the decline in muscular fitness in today's children is alarming. This can lead to lasting deficits in muscle development and have a negative impact on overall health. Well-designed resistance training (RT) could address this problem, since it has an effective positive impact on muscular strength, bone density, metabolism, and spontaneous physical activity especially in childhood. In general, muscles adapt according to physical activity stimuli. However, children show different responses to exercise and training. The physiologic differences, which are reflected in lower neuromuscular capacities and hormonal responses, but also in a better resistance to fatigue than in adults, are not yet fully understood. It is well established, that RT in children is safe, effective and has multiple benefits for health. However, the underlying mechanisms that lead to increased muscle strength are unclear and it is unknown how sustainable these are. Today's common conception is that increased muscular strength is predominantly caused by neural adaptations and changes in muscle morphology due to lower androgenic responses are negligible. Although higher neuromuscular adaptation potential is evident, it is still not sufficient to explain all strength increases, suggesting that additional mechanisms are involved in the process. Most studies are outdated, had methodological and statistical limitations, and many state-of-the-art methods have not yet been applied to children, hence, there is a need for a comprehensive, in-depth investigation to understand muscle adaptations to training and growth in children. With this better understanding of the impact and adaption to RT stimuli on neuromuscular and structural development the proposed project can serve as a foundation for more targeted prevention strategies. The aim of this study is to investigate neuromuscular, hormonal, and morphological adaptations following 4 and 20 weeks of RT, while also examining their longitudinal retention through two consecutive follow-ups over 1.5 years. In this randomized controlled trial, state-of-the-art measurement methods are employed to accurately delve into mechanisms of adaptation, some of which have not yet used in children before due to limited time or infrastructure resources. The neuromuscular assessments include maximal and explosive strength of leg extensors, voluntary activation, motor unit decomposition, as well as central and peripheral neuromuscular fatigability. The hormonal changes are measured acutely (testosterone, cortisol, IGF-1 and growth hormone) and chronically (testosterone, progesterone and IGF-1) in response to one or several training sessions. Static and dynamic ultrasound imagining is used to quantify muscle size, fascicle shortening velocity and muscle architecture. This design allows in-depth insights into short- and long-term adaptations on several physiological levels to provide a novel mechanistic understanding of muscle growth and function in children. The major innovation of this research is the integration of diverse scientific perspectives, combining insights from neuromuscular physiology, endocrinology, and muscle morphology to provide a holistic understanding of RT adaptations and development in children of both sexes. This comprehensive approach can form the basis for future training programs, enabling next generations to better understand the potential impact of musculature on health.

Вмешательства

• Поведенческое resistance training intervention
  The RT intervention focuses on knee extensor muscles, following current guidelines. Children will attend two supervised 1-hour sessions per week, proven sufficient for adaptations. Trained coaches and a scientific assistant, supported by master students, will document the sessions. Sessions are spaced 48 hours apart, totaling 40 over 20 weeks, with eight sessions between PRE and MID. Each session has three phases: warm-up, strength, and coordination. Warm-up involves whole-body games to increas

Первичные конечные точки

• maximal isometric voluntary contraction of knee extensor muscles [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]

Вторичные конечные точки (7)

• Neuromuscular fatiguability [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]
• Power and explosive force [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]
• Voluntary activation [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]
• Muscle size [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]
• Motor unit activity [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]
• Acute and chronic hormonal changes [Срок оценки: Resting concentrations: from enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each. Acute changes from one training session: in 2nd and 2nd-last week]
• Muscle fascicle shortening velocity [Срок оценки: From enrollment (PRE) to after 4 weeks of intervention (MID), to the end of Intervention (POST), as well as to the two Follow-ups after 9 month each.]

Критерии участия

Критерии включения

• Able to travel 6 times to the Departement of Sports, Exercise and Health for the measurements
• Able to travel 2 times per week to CrossFit Basel GmbH for 20 weeks to participate on the training
• Able to verbally communicate pain or discomfort
• Signed informed consent information from the parents

Критерии исключения

• Any acute or chronic medical condition
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc.
• Regular participation in resistance training (incl. CrossFit®) in the previous year.

Критерии приведены из реестра в оригинале (на английском). Окончательную оценку соответствия проводит исследовательский центр.

Здоровые добровольцы: Да

Дизайн исследования

Распределение

Рандомизированное

Модель

Параллельные группы

Маскирование

Двойное слепое

Основная цель

Лечение

Центры проведения

Швейцария · 1 центр

• Department of Sport, Exercise and Health — Basel

Идентификаторы

NCT: NCT06594900 · decade-fit

Первоисточники (государственные реестры)

• ClinicalTrials.gov (NIH, США)

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