November 15, 2021

Phuong “Lisa” Ha, Ph.D. Student

The University of British Columbia, Okanagan Campus, SPIN Lab

The KT committee is introducing a new format for Knowledge Translation articles with an emphasis on how current research may impact practitioners. This month’s article is written by Phuong “Lisa” Ha.

Take home message

  • Older males and females fatigue more during fast, repetitive shortening contractions of the quadriceps and biceps brachii than younger adults
  • Regardless of participants’ sex, during repetitive shortening contractions, muscle velocity is reduced more for the quadriceps than biceps brachii of older adults
  • Older adults who experience greater fatigue during fast, shortening contractions of the quadriceps also have slower walking speeds and poorer balance
  • Older adults should focus on exercises that improve muscle velocity and power to maintain physical function into old age


  • Muscle velocity and power are better indicators of physical function than muscle strength in older adults
  • Fatigue can be a limitation for older adults when performing activities of daily living (walking, getting out of a chair, and standing)
  • Sex-related differences exist during isometric fatiguing contractions, but less is known about dynamic contractions and if the amount of fatigue depends on the muscle group (lower versus upper limb)

How the study was done

  • 35 young adults (18-31 years, 16 males and 19 females) and 32 older adults (60-85 years, 18 males and 14 females) performed two fatiguing tasks that involved shortening the muscle as fast as possible against a relative resistance (20% maximal isometric strength)
  • The fatiguing tasks consisted of 30 concentric elbow flexion (biceps brachii) or knee extension (quadriceps) contractions and were performed on separate days
  • Muscle strength, velocity and power were evaluated before and after fatiguing exercise
  • Walking speed and endurance as well as balance ability was assessed in the older adults

What the researchers found

  • Older adults had greater decreases in muscle velocity and power following the fatiguing exercise than younger adults, regardless of muscle group or sex
  • Declines in muscle velocity were greater for the quadriceps than biceps brachii with greater age-related differences for the quadriceps
  • In older adults, fatigue-related decreases in quadriceps muscle velocity was related to walking speed and endurance as well as balance ability. However, there were no relationships between fatigue-related decreases of the biceps brachii and physical function


  • Older adults had greater fatigue during shortening contractions of the quadriceps and biceps brachii than younger adults. Further, the age-related differences were greater for the quadriceps than biceps brachii, regardless of sex
  • Greater decreases of muscle velocity following the fatiguing exercise were related to poorer walking and balance performance in older adults

Senefeld, J., Yoon, T., & Hunter, S. K. (2017). Age differences in dynamic fatigability and variability of arm and leg muscles: Associations with physical function. Experimental gerontology, 87, 74-83.

This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.