title: Lower-Body Muscle Structure and Jump Performance of Stronger and Weaker Surfing Athletes.
abstract: OBJECTIVE
  To identify whether there are any significant differences in the lower-body muscle structure and countermovement-jump (CMJ) and squat-jump (SJ) performance between stronger and weaker surfing athletes.
  
  
  METHODS
  Twenty elite male surfers had their lower-body muscle structure assessed with ultrasonography and completed a series of lower-body strength and jump tests including isometric midthigh pull (IMTP), CMJ, and SJ. Athletes were separated into stronger (n = 10) and weaker (n = 10) groups based on IMTP performance.
  
  
  RESULTS
  Large significant differences were identified between the groups for vastus lateralis (VL) thickness (P = .02, ES = 1.22) and lateral gastrocnemius (LG) pennation angle (P = .01, ES = 1.20), and a large nonsignificant difference was identified in LG thickness (P = .08, ES = 0.89). Furthermore, significant differences were present between the groups for peak force, relative peak force, and jump height in the CMJ and SJ (P < .01-.05, ES = 0.90-1.47) and eccentric peak velocity, as well as vertical displacement of the center of mass during the CMJ (P < .01, ES = 1.40-1.41).
  
  
  CONCLUSIONS
  Stronger surfing athletes in this study had greater VL and LG thickness and LG pennation angle. These muscle structures may explain their better performance in the CMJ and SJ. A unique finding in this study was that the stronger group appeared to better use their strength and muscle structure for braking as they had significantly higher eccentric peak velocity and vertical displacement during the CMJ. This enhanced eccentric phase may have resulted in a greater production and subsequent utilization of stored elastic strain energy that led to the significantly better CMJ performance in the stronger group.
authors.affiliation: Hurley Surfing Australia High Performance Centre, Casuarina Beach, Australia.
authors.forename: Josh L
authors.initials: JL
authors.lastname: Secomb
authors.forename: Sophia
authors.initials: S
authors.lastname: Nimphius
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Farley
authors.forename: Lina
authors.initials: L
authors.lastname: Lundgren
authors.forename: Tai T
authors.initials: TT
authors.lastname: Tran
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Sheppard
mesh_terms: D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology; D014463:Ultrasonography; D055815:Young Adult