title: The effects of a high-intensity free-weight back-squat exercise protocol on postural stability in resistance-trained males.
abstract: The purpose of this study was to investigate the effects of a high-intensity free-weight back-squat exercise on postural stability characteristics in resistance-trained males. Eighteen college-aged (mean ± SD: age = 22.9 ± 2.9 years; height = 175.8 ± 6.4 cm; mass = 86.3 ± 9.3 kg), resistance-trained males performed postural stability testing before and after completing five sets of eight repetitions of back-squat exercises at 80% of one-repetition maximum. A commercial balance testing device was used to assess sway index at pre- and at 0, 5, 10, 15 and 20 min post-exercise. Each balance assessment consisted of four, 20-s static stance conditions: eyes-open firm surface, eyes-closed firm surface, eyes-open soft surface and eyes-closed soft surface. Sway index was greater (P = 0.001-0.020) at Post 0 than at all other time points. No differences (P > 0.05) were observed between any other time phases. Sway index was greater (P < 0.001) for eyes-closed soft surface than all other conditions. These findings revealed sway index for all conditions significantly increased following completion of the back-squat; however, sway index recovered within 5 min of exercise. Higher sway index values as a result of neuromuscular fatigue induced by a back-squat exercise may have performance and injury risk consequences to subsequent activities that rely on postural stability. However, these findings suggest balance impairments may recover in ~5 min following high-intensity lower body resistance exercise.
authors.affiliation: a Applied Musculoskeletal and Human Physiology Laboratory, Department of Health and Human Performance , Oklahoma State University , Stillwater , OK , USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Thiele
authors.forename: E C
authors.initials: EC
authors.lastname: Conchola
authors.forename: T B
authors.initials: TB
authors.lastname: Palmer
authors.forename: J M
authors.initials: JM
authors.lastname: DeFreitas
authors.forename: B J
authors.initials: BJ
authors.lastname: Thompson
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D055070:Resistance Training; D014891:Weight Lifting / Q000502:physiology*; D055815:Young Adult
keywords: balance; fatigue; posture; recovery; resistance exercise