title: The acute effects of unilateral ankle plantar flexors static- stretching on postural sway and gastrocnemius muscle activity during single-leg balance tasks.
abstract: The aim of this study was to investigate the acute effects of unilateral ankle plantar flexors static- stretching on surface electromyography (sEMG) and the center of pressure (COP) during a single-leg balance task in both lower limbs. Fourteen young healthy, non-athletic individuals performed unipodal quiet standing for 30s before and after (stretched limb: immediately post-stretch, 10 and 20 minutes and non-stretched limb: immediately post-stretch) a unilateral ankle plantar flexor static- stretching protocol [6 sets of 45s/15s, 70-90% point of discomfort (POD)]. Postural sway was described using the COP area, COP speed (antero-posterior and medio-lateral directions) and COP frequency (antero-posterior and medio-lateral directions). Surface EMG (EMG integral [IEMG] and Median frequency[FM]) was used to describe the muscular activity of gastrocnemius lateralis. Ankle dorsiflexion passive range of motion increased in the stretched limb before and after the static-stretching protocol (mean ± SD: 15.0° ± 6.0 and 21.5° ± 7.0 [p < 0.001]). COP area and IEMG increased in the stretch limb between pre-stretching and immediately post-stretching (p = 0.015 and p = 0.036, respectively). In conclusion, our static- stretching protocol effectively increased passive ankle ROM. The increased ROM appears to increase postural sway and muscle activity; however these finding were only a temporary or transient effect. Key PointsThe postural control can be affected by static- stretching protocol.The lateral gastrocnemius muscle action was increased after the static- stretching protocol.The static- stretching effects remain for less than 10 minutes.
authors.affiliation: Department of Human Movement Sciences, Methodist University of Piracicaba , Piracicaba, São Paulo, Brazil.
authors.forename: Bráulio N
authors.initials: BN
authors.lastname: Lima
authors.affiliation: Department of Rehabilitation Science, Human Motion Analysis Laboratory, Universidade Nove de Julho , São Paulo, Brazil.
authors.forename: Paulo R G
authors.initials: PR
authors.lastname: Lucareli
authors.affiliation: Department of Human Movement Sciences, Methodist University of Piracicaba , Piracicaba, São Paulo, Brazil.
authors.forename: Willy A
authors.initials: WA
authors.lastname: Gomes
authors.affiliation: Department of Human Movement Sciences, Methodist University of Piracicaba , Piracicaba, São Paulo, Brazil.
authors.forename: Josinaldo J
authors.initials: JJ
authors.lastname: Silva
authors.affiliation: Department of Rehabilitation Science, Human Motion Analysis Laboratory, Universidade Nove de Julho , São Paulo, Brazil.
authors.forename: Andre S
authors.initials: AS
authors.lastname: Bley
authors.affiliation: Department of Physical Therapy, University of New England , Portland, Maine, USA.
authors.forename: Erin H
authors.initials: EH
authors.lastname: Hartigan
authors.affiliation: Department of Human Movement Sciences, Methodist University of Piracicaba , Piracicaba, São Paulo, Brazil ; Faculty of Physical Education (YMCA) , Sorocaba, São Paulo, Brazil.
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Marchetti
keywords: Balance; motor control; postural stability; stabilometry