Shortening-induced depression of voluntary force in unfatigued and fatigued human adductor pollicis muscle

• Published in: Journal of applied physiology (1985) Vol. 94; no. 1; pp. 69 - 74
• Main Authors: De Ruiter, C. J, De Haan, A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.01.2003; American Physiological Society
• Subjects: Adult; Anatomy & physiology; Biological and medical sciences; Electric Stimulation; Fatigue; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Muscle Contraction - physiology; Muscle Fatigue - physiology; Muscle, Skeletal - physiology; Muscular system; Striated muscle. Tendons; Thumb; Time Factors; Vertebrates: osteoarticular system, musculoskeletal system; Human; electrical stimulation; force deficit; Adductor pollicis muscle; Force; Electrical stimulus; Volunteer; Shortening; Fatigue; Activation; velocity; Striated muscle; voluntary activation; Muscle contraction; Response stimulus relation
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00672.2002

Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, 1081 BT Amsterdam, The Netherlands The goals of this study were to investigate adductor pollicis muscle ( n  = 7) force depression after maximal electrically stimulated and voluntarily activated isovelocity (19 and 306°/s) shortening contractions and the effects of fatigue. After shortening contractions, redeveloped isometric force was significantly ( P  < 0.05) depressed relative to isometric force obtained without preceding shortening. For voluntarily and electrically stimulated contractions, relative force deficits respectively were (means ± SE) 25.0 ± 3.5 and 26.6   ± 1.9% (19°/s), 7.8 ± 2.2 and 11.5 ± 0.6% (306°/s), and 23.9 ±   4.4 and 31.6 ± 4.7% (19°/s fatigued). The relative force deficit was significantly smaller after fast compared with slow shortening contractions, whereas activation manner and fatigue did not significantly affect the deficit. It was concluded that in unfatigued and fatigued muscle the velocity-dependent relative force deficit was similar with maximal voluntary activation and electrical stimulation. These findings have important implications for experimental studies of force-velocity relationships. Moreover, if not accounted for in muscle models, they will contribute to differences observed between the predicted and the actually measured performance during in vivo locomotion. force deficit; voluntary activation; electrical stimulation; velocity