Walking net V˙O2 rises with advancing age in older women: where to go from here?

• Published in: European journal of applied physiology Vol. 124; no. 8; pp. 2523 - 2531
• Main Authors: Carter, Stephen J., Singh, Harshvardhan, Long, Emily B., Martins, Catia, McCarthy, John P., Bickel, C. Scott, Bryan, David R., Hunter, Gary R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2024; Springer Nature B.V
• Subjects: Age; Biomedical and Life Sciences; Biomedicine; Calorimetry; Energetics of Human Locomotion; Human Physiology; Knee; Muscle contraction; Occupational Medicine/Industrial Medicine; Original Article; Sports Medicine; Walking; Knee extension; Mobility; Sarcopenia; Walking speed; Menopause; Skeletal muscle
• ISSN: 1439-6319; 1439-6327; 1439-6327
• DOI: 10.1007/s00421-024-05465-8

Purpose
Walking net
V
˙
O
2
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
V
˙
O
2
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
V
˙
O
2
. Maximal oxygen uptake (
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
V
˙
O
2
were positively related to age. Notably, these relationships strengthened after adjusting for
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
V
˙
O
2
, respectively. Further analyses suggested knee extensor MVC moderates the relationship between non-graded net
V
˙
O
2
and age, accounting for 9% of the variance [ΔR
2
 = 0.090,
F
(1,31) = 4.13,
p
 = 0.05].
Conclusion
These data support the premise that, in older women, walking net
V
˙
O
2
rises with advancing age, and additionally, the RTD:MVC ratio and PF
ROM
are independent correlates of non-graded net
V
˙
O
2
. Exercise interventions with a high degree of training specificity including explosive, velocity-based elements may promote independent mobility in older women.