title: Combined effects of fatigue and temperature manipulation on skeletal muscle electrical and mechanical characteristics during isometric contraction.
abstract: Peripheral fatigue and muscle cooling induce similar effects on sarcolemmal propagation properties. The aim of the study was to assess the combined effects of muscle temperature (Tm) manipulation and fatigue on skeletal muscle electrical and mechanical characteristics during isometric contraction. After maximum voluntary contraction (MVC) assessment, 16 participants performed brief and sustained isometric tasks of different intensities in low (Tm(L)), high (Tm(H)) and neutral (Tm(N)) temperature conditions, before and after a fatiguing exercise (6s on/4s off at 50% MVC, to the point of fatigue). During contraction, the surface electromyogram (EMG) and force were recorded from the biceps brachii muscle. The root mean square (RMS) and conduction velocity (CV) were calculated off-line. After the fatiguing exercise: (i) MVC decreased similarly in all Tm conditions (P<0.05), while EMG RMS did not change; and (ii) CV decreased to a further extent in Tm(L) compared to Tm(N) and Tm(H) in all brief and sustained contractions (P<0.05). The larger CV drop in Tm(L) after fatigue suggests that Tm(L) and fatigue have a combined and additional effect on sarcolemmal propagation properties. Despite these changes, force generating capacity was not affected by Tm manipulation. A compensatory mechanism has been proposed to explain this phenomenon.
authors.affiliation: Department of Sport, Nutrition and Health Sciences, University of Milan, Milan, Italy. emiliano.ce@unimi.it
authors.forename: Emiliano
authors.initials: E
authors.lastname: Cè
authors.forename: Susanna
authors.initials: S
authors.lastname: Rampichini
authors.forename: Luca
authors.initials: L
authors.lastname: Agnello
authors.forename: Eloisa
authors.initials: E
authors.lastname: Limonta
authors.forename: Arsenio
authors.initials: A
authors.lastname: Veicsteinas
authors.forename: Fabio
authors.initials: F
authors.lastname: Esposito
mesh_terms: D001831:Body Temperature / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D055815:Young Adult