Journal of Sport and Health Science最新文献

Background: Physical fitness in childhood and adolescence is associated with a variety of health outcomes and is a powerful marker of current and future health. However, inconsistencies in tests and protocols limit international monitoring and surveillance. The objective of the study was to seek international consensus on a proposed, evidence-informed, Youth Fitness International Test (YFIT) battery and protocols for health monitoring and surveillance in children and adolescents aged 6-18 years.

Methods: We conducted an international modified Delphi study to evaluate the level of agreement with a proposed, evidence-based, YFIT of core health-related fitness tests and protocols to be used worldwide in 6- to 18-year-olds. This proposal was based on previous European and North American projects that systematically reviewed the existing evidence to identify the most valid, reliable, health-related, safe, and feasible fitness tests to be used in children and adolescents aged 6-18 years. We designed a single-panel modified Delphi study and invited 216 experts from all around the world to answer this Delphi survey, of whom one-third are from low-to-middle income countries and one-third are women. Four experts were involved in the piloting of the survey and did not participate in the main Delphi study to avoid bias. We pre-defined an agreement of ≥80% among the expert participants to achieve consensus.

Results: We obtained a high response rate (78%) with a total of 169 fitness experts from 50 countries and territories, including 63 women and 61 experts from low- or middle-income countries/territories. Consensus (>85% agreement) was achieved for all proposed tests and protocols, supporting the YFIT battery, which includes weight and height (to compute body mass index as a proxy of body size/composition), the 20-m shuttle run (cardiorespiratory fitness), handgrip strength, and standing long jump (muscular fitness).

Conclusion: This study contributes to standardizing fitness tests and protocols used for research, monitoring, and surveillance across the world, which will allow for future data pooling and the development of international and regional sex- and age-specific reference values, health-related cut-points, and a global picture of fitness among children and adolescents.

Background: While Nordic hamstring exercise (NHE) training has been shown to reduce hamstring strains, the muscle-specific adaptations to NHE across the 4 hamstrings remain unclear. This study investigates architectural and microstructural adaptations of the biceps femoris short head (BFsh), biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) in response to an NHE intervention.

Methods: Eleven subjects completed 9 weeks of supervised NHE training followed by 3 weeks of detraining. Magnetic resonance imaging was performed at pre-training, post-training, and detraining to assess architectural (volume, fiber tract length, and fiber tract angle) and microstructural (axial (AD), mean (MD), radial (RD) diffusivities, and fractional anisotropy (FA)) parameters of the 4 hamstrings.

Results: NHE training induced significant but non-uniform hamstring muscle hypertrophy (BFsh: 22%, BFlh: 9%, ST: 26%, SM: 6%) and fiber tract length increase (BFsh: 11%, BFlh: 7%, ST: 18%, SM: 10%). AD (5%), MD (4%), and RD (5%) showed significant increases, but fiber tract angle and FA remained unchanged. After detraining, only ST showed a significant reduction (8%) in volume, which remained higher than the pre-training value. While fiber tract lengths returned to baseline, AD, MD, and RD remained higher than pre-training levels for all hamstrings.

Conclusion: The 9-week NHE training substantially increased hamstring muscle volume with greater hypertrophy in ST and BFsh. Hypertrophy was accompanied by increases in fiber tract lengths and cross-sections (increased RD). After 3 weeks of detraining, fiber tract length gains across all hamstrings declined, emphasizing the importance of sustained training to maintain all the protective adaptations.

Exercise is a therapeutic approach in cancer treatment, providing several benefits. Moreover, exercise is associated with a reduced risk for developing a range of cancers and for their recurrence, as well as with improving survival, even though the underlying mechanisms remain unclear. Preclinical and clinical evidence shows that the acute effects of a single exercise session can suppress the growth of various cancer cell lines in vitro. This suppression is potentially due to altered concentrations of hormones (e.g., insulin) and cytokines (e.g., tumor necrosis factor alpha and interleukin 6) after exercise. These factors, known to be involved in tumorigenesis, may explain why exercise is associated with reduced cancer incidence, recurrence, and mortality. However, the effects of short- (<8 weeks) and long-term (≥8 weeks) exercise programs on cancer cells have been reported with mixed results. Although more research is needed, it appears that interventions incorporating both exercise and diet seem to have greater inhibitory effects on cancer cell growth in both apparently healthy subjects as well as in cancer patients. Although speculative, these suppressive effects on cancer cells may be driven by changes in body weight and composition as well as by a reduction in low-grade inflammation often associated with sedentary behavior, low muscle mass, and excess fat mass in cancer patients. Taken together, such interventions could alter the systemic levels of suppressive circulating factors, leading to a less favorable environment for tumorigenesis. While regular exercise and a healthy diet may establish a more cancer-suppressive environment, each acute bout of exercise provides a further "dose" of anticancer medicine. Therefore, integrating regular exercise could potentially play a significant role in cancer management, highlighting the need for future investigations in this promising area of research.