title: Albuterol aids resistance exercise in reducing unloading-induced ankle extensor strength losses.
abstract: While resistance exercise (REX) reduces ankle extensor (AE) mass and strength deficits during short-term unloading; additional treatments, concurrently administered with REX, are required to attenuate the greater losses seen with longer unloading periods. Subjects performed left leg REX, which otherwise refrained from ambulatory and weight-bearing activity for 40 days, while randomized to a capsule (placebo, albuterol) dosing regimen with no crossover to note whether albuterol helps REX mitigate unloading-induced AE losses. A third group of subjects served as unloaded controls. On days 0, 20, and 40, the following data were collected from the left leg: calf cross-sectional area and AE strength measures. Cross-sectional area was estimated using anthropometric methodology, whereas AE strength data were obtained from eight unilateral calf-press repetitions on an inertial-based REX device. Repeated-measures mixed-factorial 3 x 3 analyses of covariance, with day 0 values as a covariate, revealed group x time interactions for the strength variables eccentric total work (ETW) and average power (EAP). Tukey's honestly significant difference shows REX-placebo subjects incurred significant ETW and EAP losses by day 40, whereas the REX-albuterol treatment evoked strength gains to those same variables without concurrent muscle accretion. Corresponding concentric variables did not display similar changes. Day 40 control data significantly declined for many variables; relative to the REX-albuterol treatment, some losses were significant after 20 days. ETW and EAP gains to unloaded AE may be due to one or more mechanisms. Continued research identifying mechanisms responsible for such changes, as well as the safety of REX-albuterol administration in other models, is warranted.
authors.affiliation: Exercise Physiology Laboratory, University fo Nevada, USA. john-caruso@utulsa.edu
authors.forename: John
authors.initials: J
authors.lastname: Caruso
authors.forename: John
authors.initials: J
authors.lastname: Hamill
authors.forename: Miki
authors.initials: M
authors.lastname: Yamauchi
authors.forename: Dean
authors.initials: D
authors.lastname: Mercado
authors.forename: Tim
authors.initials: T
authors.lastname: Cook
authors.forename: Brian
authors.initials: B
authors.lastname: Higginson
authors.forename: Sean
authors.initials: S
authors.lastname: O'Meara
authors.forename: Jeff
authors.initials: J
authors.lastname: Elias
authors.forename: Steve
authors.initials: S
authors.lastname: Siconolfi
mesh_terms: D000420:Albuterol / Q000494:pharmacology*; D000842:Ankle / Q000502:physiology; D004311:Double-Blind Method; D006801:Humans; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D005082:Physical Exertion / Q000187:drug effects* / Q000502:physiology; D014891:Weight Lifting / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D000420:Albuterol