The research, led by Ferdinand Anokwuru and Scott R. Bauer with colleagues at the Charles R. Drew University of Medicine and Science, the San Francisco Coordinating Center, the University of Pittsburgh, Wake Forest University, and other institutions, drew on baseline data from the Study of Muscle, Mobility and Aging, known as SOMMA. This cohort was designed to uncover the cellular biology behind age-related loss of mobility, and it gave the team an unusual opportunity. Rather than relying on questionnaires alone, the investigators measured the actual physiology of energy production and energy expenditure in 629 community-dwelling adults aged seventy and older, then asked whether those measurements tracked with the severity of lower urinary tract symptoms.

The technical core of the study rests on three quantities. The first is VO2peak, the maximum rate of oxygen consumption a person can achieve during a symptom-limited treadmill cardiopulmonary exercise test using a modified Balke protocol. This is the classic measure of cardiorespiratory fitness, the ceiling of the body’s aerobic engine. The second is the energetic cost of walking, abbreviated ECw, defined here as the average oxygen consumption while walking slowly at a fixed treadmill speed of 0.67 meters per second for five minutes. This captures how metabolically expensive it is for an individual to perform one of the most fundamental tasks of daily life. The third quantity is the cost-capacity ratio, or CCR, calculated as one hundred times the energetic cost of walking divided by VO2peak. In plain terms, the CCR expresses what fraction of a person’s total aerobic capacity is consumed simply by walking at a slow pace.

The logic behind the cost-capacity ratio is what makes this study conceptually striking. Two older adults can have identical walking costs but very different fitness levels, and two can have identical fitness levels but very different walking costs. Only the ratio captures the lived experience of effort. When the energy required to move approaches the energy available to move, every step feels harder, and the margin left over for everything else, including the physiological work of maintaining continence and bladder control, shrinks. The researchers hypothesized that this energetic squeeze might be visible in urinary symptoms, which previous work has repeatedly linked to mobility limitation, frailty, and functional decline.

To measure symptoms, the team used the 10-item LURN Symptom Index, a validated instrument that scores lower urinary tract symptoms over the past week on a scale from zero to thirty-eight, with higher scores indicating worse symptoms. They then fitted linear and logistic regression models relating VO2peak, ECw, and CCR to symptom scores and to the presence of urinary incontinence. Crucially, the models were adjusted for a demanding set of potential confounders: demographics, anthropometrics such as body size, smoking status, multimorbidity, and obstetric factors in women. The investigators also tested for interactions by sex, recognizing that the anatomy and physiology of the lower urinary tract differ substantially between men and women.

The results were nuanced but suggestive. In minimally adjusted models, both a higher energetic cost of walking and a higher cost-capacity ratio were associated with worse total scores on the LURN Symptom Index. For the cost-capacity ratio, each one standard deviation increase corresponded to a beta of 0.36 points on the symptom scale, with a ninety-five percent confidence interval of 0.05 to 0.67. When the models were fully adjusted for the complete set of confounders, however, the confidence intervals widened to include zero, meaning these overall associations could no longer be distinguished from chance. The authors are appropriately careful on this point: the evidence points toward a modest association rather than a dramatic one.

One finding did survive full statistical adjustment, and it is the most intriguing result in the paper. A higher energetic cost of walking was associated with significantly greater odds of urinary incontinence in men, with an odds ratio of 1.67 and a confidence interval of 1.10 to 2.54, but the same association was not observed in women. This sex-specific pattern raises questions the study was not designed to answer. In men, incontinence and other lower urinary tract symptoms often arise in the context of prostate enlargement and bladder outlet changes, and it is possible that a metabolically expensive gait pattern reflects underlying vascular or muscular deterioration that also compromises the systems supporting urinary control. In women, obstetric history and pelvic floor mechanics may dominate the symptom picture in ways that swamp any energetic signal.

Notably, VO2peak by itself was not associated with lower urinary tract symptoms in any of the adjusted models. This null result is informative. It suggests that raw aerobic capacity, the sheer size of the engine, matters less than the relationship between that capacity and the cost of using it. A person with a modest VO2peak who walks efficiently may fare as well symptomatically as someone with a larger engine and a costlier gait. This reframing matters for intervention design, because it implies that reducing the energetic cost of walking, through gait retraining, weight management, or improved muscle mitochondrial function, could be as meaningful as raising fitness itself.

The study builds on a growing body of SOMMA research connecting energetics to aging outcomes. Earlier work from the same cohort has shown that lower muscle mitochondrial energetics are associated with greater phenotypic frailty and with multimorbidity burden, and that walking energetics and perceived fatigability interact with gait speed. Prior epidemiological studies have also linked physical activity to urinary health, finding that higher activity levels are associated with lower risk of urinary incontinence in women and reduced lower urinary tract symptom risk in men, while obesity increases risk. The new analysis adds a mechanistic dimension to this literature by proposing a specific physiological pathway, the cost-capacity relationship, through which overall physical condition and urinary symptoms could be connected.

The authors are candid about the limitations. The data are cross-sectional, so the direction of the relationship cannot be established. It is entirely possible that severe urinary symptoms, particularly nocturia that fragments sleep or incontinence that discourages leaving home, lead to reduced physical activity, deconditioning, and a rising cost-capacity ratio rather than the reverse. The associations, where they existed, were modest, and the fully adjusted models attenuated several of them. Still, the paper’s central proposal is compelling: energetic capacity, the balance between what movement costs and what the body can supply, may represent a novel intervention target for the large population of older adults in whom lower urinary tract symptoms and mobility limitations occur together. If future longitudinal and experimental studies confirm the pathway, the humble treadmill walk test could become an unexpected window into urinary health in aging.

Subject of Research: Associations between walking energetics, cardiorespiratory fitness, and lower urinary tract symptoms in older adults

Article Title: Energetic pathway to lower urinary tract symptoms in older adults: associations with cardiorespiratory fitness and walking energetics in the study of muscle, mobility and aging

Article References: Anokwuru, F., Mansfield, T. A., Chen, B. H., Glynn, N. W., Mau, T., Kritchevsky, S. B., McVary, K., Gill, H. K., Barnes, H. N., Goodpaster, B. H., Cummings, S. R., Cawthon, P. M., & Bauer, S. R. (2026). Energetic pathway to lower urinary tract symptoms in older adults: associations with cardiorespiratory fitness and walking energetics in the study of muscle, mobility and aging. GeroScience. https://doi.org/10.1007/s11357-026-02524-0

Image Credits: AI Generated

DOI: 10.1007/s11357-026-02524-0

Keywords: lower urinary tract symptoms, urinary incontinence, aging, cardiorespiratory fitness, VO2peak, walking energetics, cost-capacity ratio, GeroScience, SOMMA, geriatrics, mobility, energy metabolism