title: Effects of heavy-resistance strength and balance training on unilateral and bilateral leg strength performance in old adults.
abstract: The term "bilateral deficit" (BLD) has been used to describe a reduction in performance during bilateral contractions when compared to the sum of identical unilateral contractions. In old age, maximal isometric force production (MIF) decreases and BLD increases indicating the need for training interventions to mitigate this impact in seniors. In a cross-sectional approach, we examined age-related differences in MIF and BLD in young (age: 20-30 years) and old adults (age: >65 years). In addition, a randomized-controlled trial was conducted to investigate training-specific effects of resistance vs. balance training on MIF and BLD of the leg extensors in old adults. Subjects were randomly assigned to resistance training (n = 19), balance training (n = 14), or a control group (n = 20). Bilateral heavy-resistance training for the lower extremities was performed for 13 weeks (3 × / week) at 80% of the one repetition maximum. Balance training was conducted using predominately unilateral exercises on wobble boards, soft mats, and uneven surfaces for the same duration. Pre- and post-tests included uni- and bilateral measurements of maximal isometric leg extension force. At baseline, young subjects outperformed older adults in uni- and bilateral MIF (all p < .001; d = 2.61-3.37) and in measures of BLD (p < .001; d = 2.04). We also found significant increases in uni- and bilateral MIF after resistance training (all p < .001, d = 1.8-5.7) and balance training (all p < .05, d = 1.3-3.2). In addition, BLD decreased following resistance (p < .001, d = 3.4) and balance training (p < .001, d = 2.6). It can be concluded that both training regimens resulted in increased MIF and decreased BLD of the leg extensors (HRT-group more than BAL-group), almost reaching the levels of young adults.
authors.affiliation: University of Potsdam, Division of Training and Movement Sciences, Research Focus Cognition Sciences, Potsdam, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Beurskens
authors.affiliation: Albert-Ludwigs-University of Freiburg, Institute of Sport and Sport Science, Freiburg, Germany.
authors.forename: Albert
authors.initials: A
authors.lastname: Gollhofer
authors.affiliation: University of Potsdam, Division of Training and Movement Sciences, Research Focus Cognition Sciences, Potsdam, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Muehlbauer
authors.affiliation: ASPIRE-Academy for Sports Excellence, Doha, Qatar; University College London, Institute of Sports Exercise and Health, London, United Kingdom.
authors.forename: Marco
authors.initials: M
authors.lastname: Cardinale
authors.affiliation: University of Potsdam, Division of Training and Movement Sciences, Research Focus Cognition Sciences, Potsdam, Germany.
authors.forename: Urs
authors.initials: U
authors.lastname: Granacher
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D007866:Leg / Q000254:growth & development / Q000502:physiology*; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000254:growth & development / Q000502:physiology*; D004856:Postural Balance; D055070:Resistance Training