Affiliations: [a] Department of Community Medicine and Rehabilitation,
Physiotherapy, Umeå University, Umeå Sweden | [b] Department of Biomedical Engineering and Informatics,
University Hospital, Umeå Sweden
Note: [] Address for correspondence: Britta Lindström, Department of
Community Medicine and Rehabilitation, Physiotherapy, Building 15, Umeå
University, Sweden, 901 87 Umeå Sweden. Tel.: +46 90 786 92 68; Fax: +46
90 786 91 10; E-mail: britta.lindstrom@physiother.umu.se
Abstract: The overall aim was to investigate the fatigue pattern and perceived
fatigue during repetitive dynamic contractions in young and older men and
women. Sixteen older men and women (mean age 73 ± 3 years) and 22 young
men and women (mean age 28 ± 6 years) performed 100 repeated maximum
concentric isokinetic knee extension contractions at
90°·s^{-1} (1.57
rad·s^{-1}). Throughout the 100 contractions, peak
torque (PT) and surface electromyography (EMG) signals from the rectus femoris
muscle and the vastus lateralis muscle were recorded simultaneously, together
with perceived fatigue (CR-10 scale of Borg). The mean frequency of the power
spectrum (MNF) and the root mean square of the signal amplitude (RMS) of the
EMG were affected by age and with a sex related difference but for PT the
difference of the fatigue pattern was most evident between the sexes. In
addition, the young men rated the highest fatigue. Based on EMG, PT and ratings
of perceived fatigue it was concluded that the old men fatigued most, the old
women fatigued least and the young men perceived greatest fatigue.
