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Effects of contraction duration on low-frequency fatigue in voluntary and electrically induced exercise of quadriceps muscle in humans

Ratkevicius, A; Skurvydas, A; Povilonis, E; Quistorff, B and Lexell, Jan LU (1998) In European Journal of Applied Physiology and Occupational Physiology 77(5). p.462-468
Abstract
The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square... (More)
The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square (EMGrms) of the vastus lateralis muscle was evaluated. The 20-Hz torque:100-Hz torque (20:100 Hz torque) ratio was reduced more after electrically induced than after voluntary exercise (P < 0.05). During electrically induced exercise, the decrease in 20:100 Hz torque ratio was gradually (P < 0.05) reduced as the individual contractions shortened. During voluntary exercise, the decrease in 20:100 Hz torque ratio and the increase in EMGrms were greater in protocol 1 (P < 0.01) than in protocols 2 and 3, which did not differ from each other. In conclusion, our results showed that LFF is dependent on the duration of individual muscle contractions during repetitive isometric exercise and that the electrically induced exercise produced a more pronounced LFF compared to voluntary exercise of submaximal intensity. It is suggested that compensatory recruitment of faster-contracting motor units is an additional factor affecting the severity of LFF during voluntary exercise. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Electrical stimulation, Fatigue, Muscle contraction, Muscles
in
European Journal of Applied Physiology and Occupational Physiology
volume
77
issue
5
pages
462 - 468
publisher
Springer
external identifiers
  • pmid:9562299
  • scopus:0031967832
ISSN
0301-5548
DOI
10.1007/s004210050361
language
English
LU publication?
yes
id
ef51ea0b-4648-4b2c-bc6a-dbd9aeef1359 (old id 1113546)
date added to LUP
2008-07-15 12:25:00
date last changed
2017-10-22 04:41:48
@article{ef51ea0b-4648-4b2c-bc6a-dbd9aeef1359,
  abstract     = {The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square (EMGrms) of the vastus lateralis muscle was evaluated. The 20-Hz torque:100-Hz torque (20:100 Hz torque) ratio was reduced more after electrically induced than after voluntary exercise (P &lt; 0.05). During electrically induced exercise, the decrease in 20:100 Hz torque ratio was gradually (P &lt; 0.05) reduced as the individual contractions shortened. During voluntary exercise, the decrease in 20:100 Hz torque ratio and the increase in EMGrms were greater in protocol 1 (P &lt; 0.01) than in protocols 2 and 3, which did not differ from each other. In conclusion, our results showed that LFF is dependent on the duration of individual muscle contractions during repetitive isometric exercise and that the electrically induced exercise produced a more pronounced LFF compared to voluntary exercise of submaximal intensity. It is suggested that compensatory recruitment of faster-contracting motor units is an additional factor affecting the severity of LFF during voluntary exercise.},
  author       = {Ratkevicius, A and Skurvydas, A and Povilonis, E and Quistorff, B and Lexell, Jan},
  issn         = {0301-5548},
  keyword      = {Electrical stimulation,Fatigue,Muscle contraction,Muscles},
  language     = {eng},
  number       = {5},
  pages        = {462--468},
  publisher    = {Springer},
  series       = {European Journal of Applied Physiology and Occupational Physiology},
  title        = {Effects of contraction duration on low-frequency fatigue in voluntary and electrically induced exercise of quadriceps muscle in humans},
  url          = {http://dx.doi.org/10.1007/s004210050361},
  volume       = {77},
  year         = {1998},
}