The Stair Climb Power Test as an Efficacy Outcome in Randomized Trials of Function Promoting Therapies in Older Men

J Gerontol A Biol Sci Med Sci. 2020 May 22;75(6):1167-1175. doi: 10.1093/gerona/glz167.


Background: Standardization of performance-based physical function measures that are reliable and responsive to intervention is necessary for efficacy trials of function promoting anabolic therapies (FPTs). Herein, we describe a standardized method of measuring stair climbing power (SCP) and evaluate its ability to assess improvements in physical function in response to an FPT (testosterone) compared to gait speed.

Methods: We used a 12-step SCP test with and without carrying a load (loaded, LSCP or unloaded, USCP) in two testosterone trials in older men. SCP was determined from mass, total step-rise, and time of ascent measured with an electronic timing system. Associations between SCP and leg press performance (strength and power), testosterone levels, and gait speed were assessed. Test-retest reliability was evaluated using interclass correlation and Bland-Altman analyses.

Results: Baseline SCP was negatively associated with age and positively with leg strength and power and gait speed. Both tests of SCP were safe and showed excellent reliability (intra-class correlation 0.91-0.97 in both cohorts). Changes in testosterone concentrations were associated with changes in USCP and LSCP, but not gait speed in mobility-limited men. Changes in leg press performance were associated with SCP in both trials.

Conclusions: Both USCP and LSCP are safe and have high test-retest reliability. Compared to gait speed, SCP is associated more robustly with leg press performance and is sensitive to testosterone therapy. The LSCP might be a more responsive outcome than gait speed to evaluate the efficacy of FPT in randomized trials.

Keywords: Physical Function; Anabolic Intervention; Muscle Power; Testosterone.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Administration, Cutaneous
  • Aged
  • Exercise Test* / methods
  • Exercise Test* / standards
  • Gels
  • Geriatric Assessment / methods
  • Humans
  • Male
  • Physical Fitness
  • Randomized Controlled Trials as Topic / methods
  • Randomized Controlled Trials as Topic / standards
  • Reproducibility of Results
  • Stair Climbing / drug effects
  • Stair Climbing / physiology*
  • Testosterone / administration & dosage
  • Testosterone / therapeutic use
  • Treatment Outcome


  • Gels
  • Testosterone