title: The Role of Trunk Muscle Strength for Physical Fitness and Athletic Performance in Trained Individuals: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  The importance of trunk muscle strength (TMS) for physical fitness and athletic performance has been demonstrated by studies reporting significant correlations between those capacities. However, evidence-based knowledge regarding the magnitude of correlations between TMS and proxies of physical fitness and athletic performance as well as potential effects of core strength training (CST) on TMS, physical fitness and athletic performance variables is currently lacking for trained individuals.
  
  
  OBJECTIVE
  The aims of this systematic review and meta-analysis were to quantify associations between variables of TMS, physical fitness and athletic performance and effects of CST on these measures in healthy trained individuals.
  
  
  METHODS
  PubMed, Web of Science, and SPORTDiscus were systematically screened from January 1984 to March 2015.
  
  
  METHODS
  Studies were included that investigated healthy trained individuals aged 16-44 years and tested at least one measure of TMS, muscle strength, muscle power, balance, and/or athletic performance.
  
  
  METHODS
  Z-transformed Pearson's correlation coefficients between measures of TMS and physical performance were aggregated and back-transformed to r values. Further, to quantify the effects of CST, weighted standardized mean differences (SMDs) of TMS and physical performance were calculated using random effects models. The methodological quality of CST studies was assessed by the Physiotherapy Evidence Database (PEDro) scale.
  
  
  RESULTS
  Small-sized relationships of TMS with physical performance measures (-0.05 ≤ r ≤ 0.18) were found in 15 correlation studies. Sixteen intervention studies revealed large effects of CST on measures of TMS (SMD = 1.07) but small-to-medium-sized effects on proxies of physical performance (0 ≤ SMD ≤ 0.71) compared with no training or regular training only. The methodological quality of CST studies was low (median PEDro score = 4).
  
  
  CONCLUSIONS
  Our findings indicate that TMS plays only a minor role for physical fitness and athletic performance in trained individuals. In fact, CST appears to be an effective means to increase TMS and was associated with only limited gains in physical fitness and athletic performance measures when compared with no or only regular training.
authors.affiliation: Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany. prieske@uni-potsdam.de.
authors.forename: Olaf
authors.initials: O
authors.lastname: Prieske
authors.affiliation: Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Muehlbauer
authors.affiliation: Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany.
authors.forename: Urs
authors.initials: U
authors.lastname: Granacher
mesh_terms: D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D006801:Humans; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D055070:Resistance Training; D060726:Torso / Q000502:physiology*