HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 104/1/75    most recent 00335.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jubeau, M. Articles by Maffiuletti, N. A. Search for Related Content PubMed PubMed Citation Articles by Jubeau, M. Articles by Maffiuletti, N. A.

Comparison between voluntary and stimulated contractions of the quadriceps femoris for growth hormone response and muscle damage

¹Laboratoire Institut National de la Santè et de la Recherche Médicale U887 Motricité-Plasticité, Faculté des Sciences du Sport, Université de Bourgogne, Dijon, France; ²Laboratorio Sperimentale di Ricerche Auxo-endocrinologiche, Istituto Auxologico Italiano, Istituto di Ricovero e Cura a Carattere Scientifico, Milan, Italy; ³School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia; and ⁴Neuromuscular Research Laboratory, Schulthess Clinic, Zürich, Switzerland

Submitted 26 March 2007 ; accepted in final form 1 November 2007

This study aimed to compare voluntary and stimulated exercise for changes in muscle strength, growth hormone (GH), blood lactate, and markers of muscle damage. Nine healthy men had two leg press exercise bouts separated by 2 wk. In the first bout, the quadriceps muscles were stimulated by biphasic rectangular pulses (75 Hz, duration 400 µs, on-off ratio 6.25–20 s) with current amplitude being consistently increased throughout 40 contractions at maximal tolerable level. In the second bout, 40 voluntary isometric contractions were performed at the same leg press force output as the first bout. Maximal voluntary isometric strength was measured before and after the bouts, and serum GH and blood lactate concentrations were measured before, during, and after exercise. Serum creatine kinase (CK) activity and muscle soreness were assessed before, immediately after, and 24, 48, and 72 h after exercise. Maximal voluntary strength decreased significantly (P < 0.05) after both bouts, but the magnitude of the decrease was significantly (P < 0.05) greater for the stimulated contractions (–22%) compared with the voluntary contractions (–9%). Increases in serum GH and lactate concentrations were significantly (P < 0.05) larger after the stimulation compared with the voluntary exercise. Increases in serum CK activity and muscle soreness were also significantly (P < 0.05) greater for the stimulation than voluntary exercise. It was concluded that a single bout of electrical stimulation exercise resulted in greater GH response and muscle damage than voluntary exercise.

neuromuscular electrical stimulation; isometric strength; blood lactate; creatine kinase; muscle soreness