Improving groundstroke velocity and accuracy is critical for tennis success. However, there is limited research available on the physical and cognitive attributes required for groundstroke performance. Therefore, the purpose of this study was to investigate the physical and cognitive characteristics and their association with groundstroke performance in junior tennis players. Thirty-four competitive junior tennis players, aged 12.59 ± 2.44 years, participated in this cross-sectional study. Cognitive tests assessing processing speed, complex attention, cognitive flexibility and problem-solving capacity and physical tests assessing flexibility, speed, agility, power, strength and anaerobic and aerobic capacity were performed. Tennis groundstroke performance was evaluated using a novel tennis groundstroke assessment. Tennis groundstroke performance was associated ( p < 0.05) with the number of hours a participant practices per week, their ranking, lower and upper body power, tennis agility test (decision and total time), linear speed, upper body strength and aerobic capacity. Specifically, an estimated 83.76% of the groundstroke velocity accuracy index variability was explained by grip strength in the dominant hand and ranking. An estimated 79.63% of the groundstroke velocity accuracy error index variability was explained by the number of hours a participant practices per week and their ranking. Our study showed an association between tennis groundstroke performance and physical but not cognitive outcomes in junior tennis players. Specific attention should be dedicated to developing the upper body strength of junior tennis players for improved groundstroke velocity and accuracy. This knowledge can assist tennis coaches in planning effective training sessions.

Sport engagement, including tennis, and physical activity have been shown to have a positive influence on cognition in children. However, age has also been found to have a strong association with cognition in youth athletes. This study examines the threshold hypothesis by investigating the moderating role of age and maturation on the association between tennis experience and cognitive measures in Australian and German junior beginner to intermediate-level tennis players. The demographic information, which includes years of tennis experience, and anthropometrics (e.g. height and weight) was collected for 48 junior tennis players. A comprehensive cognitive testing battery was then completed to assess cognitive performance, with a principle component analysis used to determine an overall cognitive performance score. Multiple regression analyses were then performed to test the relationship between tennis experience and cognitive performance as well as the moderating effects of age and maturation. The results of this study indicate that the age and maturation rather than the exposure to tennis training are related to cognitive performance. Additionally, the positive relations of tennis experience to cognitive performance were stronger in younger participants, specifically those younger than 12 years old. Therefore, tennis may not provide a stimulus large enough for further cognitive improvement once players have developed a high level of cognitive performance. While age and biological maturity will largely dictate cognitive performance in adolescents, tennis experience may play some role in the cognitive performance of children (specifically <12 years of age).

The distribution of Glm(f, z, a, and x), G3m(b0, b1, b3, b5, c3, c5, g, s, t and v), A2m(1 and 2) and Km(1) (formerly Inv(1)) allotypic determinants has been examined in specimens from the inhabitants of two transplanted Tlaxcaltecan villages (Cuanalan and Saltillo). The results indicate that Gmza;g Am1, Gmza;g Am2, Gmzax;g Am1, Gmza;bst Am1, Gmza;bst Am2, Gmf;b Am1, Gmza,b Am1, Gmza;b Am2 and Km1 are polymorphic or marginally polymorphic in both populations, while Gmza;bc3,5 Am2, Gmza;bs Am2, and Gmzax;g Am2 were detected only in Saltillo. Two related individuals from Saltillo have either a Gmf;g Am1 or Gmf;-Am1 haplotype while a third unrelated individual had either a Gmf;g Am1 or Gm-;g Am1 haplotype. The frequencies observed for "residents" of Cuanalan are similar to those for other Indian populations in Mexico. Estimation of Caucasian and African admixture within the two communities indicates significant heterogeneity among the inhabitants of Cuanalan, in that Tlaxcaltecan residents have no detectable African admixture and significantly less Caucasian admixture than recent immigrants, with Tlaxcaltecan-immigrant hybrids intermediate, while no significant variation was observed among the subdivisions of Saltillo. However, Saltillo has greater Caucasian and African admixture than Cuanalan. Admixture estimates based on Gm haplotypes appear to agree much better with known historical events than those generated by blood groups, indicating that Gm is a better estimator of admixture than blood groups under certain circumstances.

Objective: Discrepancies exist in reports of social cognition deficits in individuals with premanifest Huntington’s disease (HD); however, the reason for this variability has not been investigated. The aims of this study were to (1) evaluate group- and individual-level social cognitive performance and (2) examine intra-individual variability (dispersion) across social cognitive domains in individuals with premanifest HD. Method: Theory of mind (ToM), social perception, empathy, and social connectedness were evaluated in 35 individuals with premanifest HD and 29 healthy controls. Cut-off values beneath the median and 1.5 × the interquartile range below the 25th percentile (P25 – 1.5 × IQR) of healthy controls for each variable were established for a profiling method. Dispersion between social cognitive domains was also calculated. Results: Compared to healthy controls, individuals with premanifest HD performed worse on all social cognitive domains except empathy. Application of the profiling method revealed a large proportion of people with premanifest HD fell below healthy control median values across ToM (>80%), social perception (>57%), empathy (>54%), and social behaviour (>40%), with a percentage of these individuals displaying more pronounced impairments in empathy (20%) and ToM (22%). Social cognition dispersion did not differ between groups. No significant correlations were found between social cognitive domains and mood, sleep, and neurocognitive outcomes. Conclusions: Significant group-level social cognition deficits were observed in the premanifest HD cohort. However, our profiling method showed that only a small percentage of these individuals experienced marked difficulties in social cognition, indicating the importance of individual-level assessments, particularly regarding future personalised treatments.

Objective Dual-tasking deficiencies are common in people with Huntington disease (HD) and contribute to reduced functional independence. To date, few studies have investigated the determinants of dual-tasking deficiencies in this population. The reliability of dual-tasking measures has also been poorly investigated in HD. The purpose of this study was to investigate the influence of motor, cognitive, mood, sleep, and lifestyle on dual-tasking performance and to determine the association of disease burden outcomes on dual-tasking performance in individuals with premanifest HD. Methods Thirty-six individuals with premanifest HD and 28 age- and sex-matched healthy controls were recruited for this study. Participants performed 3 single-task (2 cognitive and 1 motor) and 2 dual-task assessments, comprising motor (postural stability) and cognitive (simple or complex mental arithmetic) components. In addition, participants performed a comprehensive clinical battery comprising motor, cognitive, mood, and sleep assessments as well as lifestyle and disease burden measures. Results Poorer sleep quality was associated with greater cognitive dual-task cost in individuals with premanifest HD. Compared with healthy controls, people with premanifest HD demonstrated an impaired capacity to dual task. Dual-task measures exhibited acceptable test–retest reliability in premanifest HD and healthy control groups Conclusions These results show that dual-tasking measures are sensitive and reliable in individuals with premanifest HD. Furthermore, poor sleep quality is associated with worse cognitive performance on dual tasks, which should be considered by rehabilitation specialists when examining and therapeutically managing dual-tasking problems in individuals with HD and other neurodegenerative populations in the future. Impact This study adds important knowledge to the sparse literature on dual-tasking deficiencies in people with HD. When examining and therapeutically managing dual-tasking problems in this and other neurodegenerative populations, rehabilitation specialists should consider that people with premanifest HD may have an impaired capacity to dual task. Clinicians also should assess sleep quality, as poorer sleep quality is associated with worse cognitive performance on dual tasks in these individuals. Lay summary If you have premanifest HD and poor quality of sleep, you may pay more attention to maintaining postural stability rather than performing arithmetic calculations to reduce the risk of falling.