Effect of position and exercise on measurement of muscle quantity and quality: towards a standardised pragmatic protocol for clinical practice

Carly Welch*, Zeinab Majid, Isabelle Andrews, Zaki Hassan-Smith, Vicky Kamwa, Hannah Picton, Daisy Wilson, Thomas A Jackson

*Corresponding author for this work

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BACKGROUND: Ultrasonography is an emerging non-invasive bedside tool for muscle quantity/quality assessment; Bioelectrical Impedance Analysis (BIA) is an alternative non-invasive bedside measure of body composition, recommended for evaluation of sarcopenia in clinical practice. We set out to assess impact of position and exercise upon measures towards protocol standardisation.

METHODS: Healthy volunteers aged 18-35 were recruited. Bilateral Anterior Thigh Thickness (BATT; rectus femoris and vastus intermedius), BATT: Subcutaneous Ratio (BATT:SCR), and rectus femoris echogenicity were measured using ultrasound and BIA was performed; 1) lying with upper body at 45° (Reclined), 2) lying fully supine at 180o (Supine), 3) sat in a chair with upper body at 90o (Sitting), and 4) after exercise Reclined. Variability of Skeletal Muscle Mass (SMM) by two different equations from BIA (SMM-Janssen, SMM-Sergi), phase angle, fat percentage, and total body (TBW), extracellular (ECW), and intracellular water (ICW) were assessed.

RESULTS: Forty-four participants (52% female; mean 25.7 years-old (SD 5.0)) were recruited. BATT increased from Reclined to Sitting (+ 1.45 cm, 1.27-1.63), and after exercise (+ 0.51, 0.29-0.73). Echogenicity reduced from Reclined to Sitting (- 2.1, - 3.9 - -0.26). SMM-Sergi declined from Reclined to Supine (- 0.65 kg, - 1.08 - - 0.23) and after exercise (- 0.70 kg, - 1.27 - -0.14). ECW increased from Reclined to Sitting (+ 1.19 L, 0.04-2.35). There were no other statistically significant changes.

CONCLUSION: Standardisation of protocols is especially important for assessment of muscle quantity by ultrasonography; BIA measurements may also vary dependent on the equations used. Where possible, participants should be rested prior to muscle ultrasonography and BIA, and flexion of the knees should be avoided.

Original languageEnglish
Article number3
Number of pages8
JournalBMC Sports Science, Medicine and Rehabilitation
Issue number1
Early online date7 Jan 2021
Publication statusPublished - Dec 2021

Bibliographical note

Funding Information:
Dr. Carly Welch is funded by the MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research through a PhD studentship. Dr. Zeinab Majid is funded by the National Institute for Health Research (NIHR) through an Academic Clinical Fellowship. Dr. Daisy Wilson is funded by the NIHR through an Academic Clinical Lectureship. Dr. Thomas Jackson and Dr. Zaki Hassan-Smith are funded by the West Midlands NIHR Clinical Research Network through the Research Scholarship programme. The views expressed in the manuscript are those of the authors and not necessarily those of the NIHR, the NHS, or the Department for Health.

Publisher Copyright:
© 2021, The Author(s).


  • Diagnostic imaging
  • Electric impedance
  • Muscles
  • Sarcopenia

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation


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