Walking net [Formula: see text] O2 rises with advancing age in older women: where to go from here?

Stephen J Carter; Harshvardhan Singh; Emily B Long; Catia Martins; John P McCarthy; C Scott Bickel; David R Bryan; Gary R Hunter

doi:10.1007/s00421-024-05465-8

Walking net $\dot{V}$ O₂ rises with advancing age in older women: where to go from here?

Eur J Appl Physiol. 2024 Apr 5. doi: 10.1007/s00421-024-05465-8. Online ahead of print.

Authors

Stephen J Carter^{1

2}, Harshvardhan Singh³, Emily B Long⁴, Catia Martins⁵, John P McCarthy³, C Scott Bickel⁶, David R Bryan⁵, Gary R Hunter⁵

Affiliations

¹ Department of Kinesiology, School of Public Health-Bloomington, Indiana University, 1025 E 7th Street Suite 044, Bloomington, IN, 47405, USA. stjcarte@iu.edu.
² Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, IN, 46202, USA. stjcarte@iu.edu.
³ Department of Physical Therapy, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
⁴ Department of Kinesiology, School of Public Health-Bloomington, Indiana University, 1025 E 7th Street Suite 044, Bloomington, IN, 47405, USA.
⁵ Department of Nutrition Sciences, School of Health Professions, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
⁶ Department of Physical Therapy, Samford University, Birmingham, AL, 35229, USA.

PMID: 38578446
DOI: 10.1007/s00421-024-05465-8

Abstract

Purpose: Walking net $\dot{V}$ O₂ tends to increase with advancing age; however, factors contributing to this relationship have not been widely described. The implications of such findings could inform targeted strategies to promote independent mobility in older adults. Herein, we evaluated the relationship between net $\dot{V}$ O₂ and age at two submaximal workloads while exploring potential moderators of this relationship.

Methods: Secondary analyses were performed on 35 older (65 ± 3 years) women who completed a battery of physical assessments including fixed-speed, non-graded and graded (+ 2.5%) treadmill walking with indirect calorimetry to determine net $\dot{V}$ O₂. Maximal oxygen uptake ( $\dot{V}$ O_2max), knee extensor maximal isometric voluntary contraction (MVC), peak rate of torque development (RTD), and plantar flexor range-of-motion (PF_ROM) were also measured.

Results: Bivariate correlations showed non-graded (r = 0.403, p = 0.017) and graded (r = 0.413, p = 0.014) net $\dot{V}$ O₂ were positively related to age. Notably, these relationships strengthened after adjusting for $\dot{V}$ O_2max. Regression modeling showed age, RTD:MVC ratio (composite of muscle performance), and PF_ROM together explained 49% and 34% of the variance in non-graded and graded net $\dot{V}$ O₂, respectively. Further analyses suggested knee extensor MVC moderates the relationship between non-graded net $\dot{V}$ O₂ and age, accounting for 9% of the variance [ΔR² = 0.090, F (1,31) = 4.13, p = 0.05].

Conclusion: These data support the premise that, in older women, walking net $\dot{V}$ O₂ rises with advancing age, and additionally, the RTD:MVC ratio and PF_ROM are independent correlates of non-graded net $\dot{V}$ O₂. Exercise interventions with a high degree of training specificity including explosive, velocity-based elements may promote independent mobility in older women.

Keywords: Knee extension; Menopause; Mobility; Sarcopenia; Skeletal muscle; Walking speed.

Abstract

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