title: Effect of abdominal bracing training on strength and power of trunk and lower limb muscles.
abstract: OBJECTIVE
  It is unknown whether maximal voluntary co-contraction of abdominal muscles, called abdominal bracing, can be a training maneuver for improving strength and power of trunk and lower limb muscles. The present study aimed to elucidate this.
  
  
  METHODS
  Twenty young adult men (23.3 ± 1.8 years) were allocated to training (TG, n = 11) or control (CG, n = 9) group. TG conducted an 8-week training program (3 days/week) consisting of 2-s maximal abdominal bracing followed by 2-s muscle relaxation (5 × 10 repetitions/day). Maximal voluntary isometric strength during trunk flexion and extension, hip extension, and knee extension, maximal lifting power from sitting position, and the thicknesses of abdominal muscles were measured before and after the intervention. In addition, surface electromyograms from trunk and lower limb muscles and intra-abdominal pressure (IAP) during the maximal abdominal bracing and maximal lifting tasks were also determined.
  
  
  RESULTS
  After the intervention, TG showed significant increases in isometric trunk extension (+14.4 %) and hip extension (+34.7 %) strength and maximal lifting power (+15.6 %), while CG did not show any changes in strength and power variables. Furthermore, TG had significant gains in the muscle thickness of the oblique internal (+22.4 %), maximal IAP during abdominal bracing (+36.8 %), and the rate of IAP rise during lifting task (+58.8 %), without corresponding changes in CG.
  
  
  CONCLUSIONS
  The current study indicates that a training style with maximal voluntary co-contraction of abdominal muscles can be an effective maneuver for increasing strength and power during movements involving trunk and hip extensions, without using external load.
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Tayashiki
authors.affiliation: Faculty of Sport Sciences, Waseda University, Mikajima, Tokorozawa, Saitama, 359-1192, Japan.|Japan Society for the Promotion of Science, Kouji, Tokyo, 102-0088, Japan.
authors.forename: Sumiaki
authors.initials: S
authors.lastname: Maeo
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Usui
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan.
authors.forename: Naokazu
authors.initials: N
authors.lastname: Miyamoto
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima, 891-2393, Japan. hkane@nifs-k.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
mesh_terms: D000009:Abdominal Muscles / Q000033:anatomy & histology / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007866:Leg / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000379:methods* / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D055815:Young Adult
keywords: Abdominal co-contraction; Abdominal muscle thickness; Electromyogram; Intra-abdominal pressure; Stabilization exercise