title: The effects of beta 2-agonists and caffeine on respiratory and limb muscle performance.
abstract: The possibility that respiratory muscle function may be improved by drug therapy is of clinical importance, but remains controversial. A series of studies concerning the effects of maximally tolerated dosages of terbutaline, tulobuterol (a new beta 2-agonist) and caffeine on respiratory muscle strength and limb muscle strength and endurance were undertaken in normal subjects. Drugs were administered orally, 2 h before study. Caffeine produced a small but statistically significant increase in the stimulated contraction force at 20 Hz, and a small beneficial effect on recovery from a fatiguing protocol; maximum voluntary contraction force of the quadriceps was increased by 3.8%. Terbutaline and tulobuterol had no beneficial effects on either respiratory or limb muscle function. We conclude that conventional dosages of these bronchodilator drugs do not greatly affect skeletal muscle performance.
authors.affiliation: Dept of Thoracic Medicine, Kings College School of Medicine and Dentistry, Denmark Hill, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Lanigan
authors.forename: T Q
authors.initials: TQ
authors.lastname: Howes
authors.forename: G
authors.initials: G
authors.lastname: Borzone
authors.forename: L G
authors.initials: LG
authors.lastname: Vianna
authors.forename: J
authors.initials: J
authors.lastname: Moxham
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects*; D010807:Physical Endurance / Q000187:drug effects; D011446:Prospective Studies; D012132:Respiratory Muscles / Q000187:drug effects*; D013726:Terbutaline / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D000318:Adrenergic beta-Agonists; D002110:Caffeine; C010809:tulobuterol; D013726:Terbutaline