ABSTRACT
The study of athlete leadership has gained momentum over the past 15 years and is recognized as a vital component of team performance. Specifically, athlete leadership has been most studied with regards to its impact on the outcome of cohesion. As a result, a current gap in this area of research is the analysis of attribute data, such as tenure and self-reported athlete leadership, and how this attribute data is related to outcomes, such as cohesion. However, much of current research examining this relationship has utilized traditional statistical methods, limiting interpretation of data because team members are inherently interdependent. One approach that considers the interdependence of team members is social network analysis (SNA). SNA facilitates the study of social structures within networks of people, such as a sports team, as well as individual attributes influencing or being influenced by the network. The present study used SNA to examine athlete leadership and cohesion within a sports team of 22 female professional hockey players. Participants self-reported tenure, completed a self-rated athlete leadership questionnaire, and rated each of their team members on network variables of athlete leadership and cohesion. The results showed that high network density and low degree centralization was found for both athlete leadership and cohesion networks, with high indegree centralities for each team member. Further, a strong correlation was found between the athlete leadership and cohesion networks (p < 0.001), indicating a positive relationship between the athlete leadership ties and the cohesion ties. Lastly, significant correlations were found between self-rated athlete leadership and the networks of athlete leadership and cohesion. Together these data suggest that a cohesive team shares leadership responsibilities with many ties between teammates.
ABSTRACT
BACKGROUND: An emerging body of the literature in the past two decades has generally shown that prior cognitive exertion is associated with a subsequent decline in physical performance. Two parallel, but overlapping, bodies of literature (i.e., ego depletion, mental fatigue) have examined this question. However, research to date has not merged these separate lines of inquiry to assess the overall magnitude of this effect. OBJECTIVE: The present work reports the results of a comprehensive systematic review and meta-analysis examining carryover effects of cognitive exertion on physical performance. METHODS: A systematic search of MEDLINE, PsycINFO, and SPORTDiscus was conducted. Only randomized controlled trials involving healthy humans, a central executive task requiring cognitive exertion, an easier cognitive comparison task, and a physical performance task were included. RESULTS: A total of 73 studies provided 91 comparisons with 2581 participants. Random effects meta-analysis showed a significant small-to-medium negative effect of prior cognitive exertion on physical performance (g = - 0.38 [95% CI - 0.46, - 0.31]). Subgroup analyses showed that cognitive tasks lasting < 30-min (g = - 0.45) and ≥ 30-min (g = - 0.30) have similar significant negative effects on subsequent physical performance. Prior cognitive exertion significantly impairs isometric resistance (g = - 0.57), motor (g = - 0.57), dynamic resistance (g = - 0.51), and aerobic performance (g = - 0.26), but the effects on maximal anaerobic performance are trivial and non-significant (g = 0.10). Studies employing between-subject designs showed a medium negative effect (g = - 0.65), whereas within-subject designs had a small negative effect (g = - 0.28). CONCLUSION: Findings demonstrate that cognitive exertion has a negative effect on subsequent physical performance that is not due to chance and suggest that previous meta-analysis results may have underestimated the overall effect.
