From the article’s Discussion section: “In this cohort study of 13 423 adults aged 65 years or older, higher objectively measured physical fitness was associated with progressively lower all-cause mortality across multiple domains, with balance and agility showing the lowest risks, followed by lower-body strength and cardiorespiratory fitness. These findings are consistent with the conceptual distinction between disease burden and functional reserve. While previous studies have relied on comorbidity counts or deficit-accumulation indices to estimate risk, our results suggest that objective measures of functional capacity may offer prognostic information beyond traditional comorbidity-based metrics. The inverse gradients observed—even after adjusting for comorbidities—suggest that physical fitness captures a distinct domain of health not fully reflected in disease checklists.
The lower risks of all-cause mortality observed for balance, agility, and lower-body strength likely reflect their central role in fall prevention and injury avoidance. Impaired balance, slowed mobility, and reduced lower-body strength are established risk factors for falls and subsequent fractures, particularly hip fractures, which are leading causes of hospitalization, disability, and excess mortality in older adults. Assessments such as the 1-leg stance and 8-foot up-and-go tests may detect early declines in neuromuscular control that precede overt disability, with lower-body strength supporting gait stability and recovery after perturbations. The dose-response associations observed support their biological relevance and clinical utility along injury-related pathways.
Sex-stratified analyses revealed that balance and agility and cardiorespiratory fitness showed the lowest risks for all-cause mortality among men, whereas lower-body strength and balance and agility had comparable risks among women.
[..] Most of the mortality differential was concentrated between the lowest quintile and the upper quintiles, suggesting that the greatest health gains may occur when individuals move out of the lowest-performing stratum. This pattern supports prioritizing intervention for the least-fit older adults.”
Two-minute Step Test (cardiorespiratory fitness): The required knee-lift height was individualized to each participant’s anatomy. The midpoint of the line connecting the anterior superior iliac spine and the midpoint of the patella was identified, and a colored tape marker was placed on the wall at that height as a visual target. With the certified examiner positioned to the side, the participant stepped in place at maximal sustainable pace for 2 minutes, raising each knee to or above the marker on every step. In line with the official testing manual, a step was counted only when both the left knee and the right knee had each been raised to the marked height; one-sided raises that fell short of the marker were not counted. The total number of such valid bilateral steps completed within 2 minutes was the recorded score. This bilateral-criterion rule ensures uniform counting across participants and examiners.
(According to the Appendix, doing more than one step a second was associated with a lower risk of dying from any cause in men and more than 90 in two minutes for women. The relationship appears to be linear.)
30-Second Chair Stand (muscular fitness): The participant sat in the center of a straight-back or folding chair without armrests (≈43 cm seat height) placed against a wall (or otherwise stabilized) for safety, with the back upright, both feet flat on the floor, and arms crossed at the chest. On the start command, the participant repeatedly stood up fully (legs completely extended) and returned to the fully seated position.
(At least 20, with more being better for women.)
One-Leg Stance with Eyes Open (balance and agility): The test was performed on a level, flat floor. With both hands placed firmly on the hips, the participant balanced on the dominant foot — with the entire sole in full contact with the floor — and lifted the non-supporting leg so that the medial side of the lifted big toe rested against the inner ankle of the supporting leg. Timing began once the participant was stable. The trial ended when (i) the lifted foot touched the floor, (ii) the supporting foot shifted, (iii) either hand left the hip, or (iv) the trunk exhibited a large sway. Timing was measured to 0.1-second precision and the final score was recorded as integer seconds (rounded to the nearest whole second). The examiner was positioned within arm’s reach. Permitted verbal cues from the examiner were limited to standardized prompts (eg, “tighten your core,” “fix your gaze on the marker ahead”).
(At least 30 seconds, and longer is better.)
8-Foot Up-and-Go (balance and agility): A straight-back or folding chair without armrests (≈43 cm seat height) was placed against a wall for stability. A cone was positioned exactly 8 feet (2.44 m) in front of the chair, measured from the front edge of the chair to the rear of the cone, with at least 4 feet (1.22 m) of clear space behind the cone for the participant to walk around. The participant sat in the chair with the back upright, hands on the thighs, and feet flat on the floor in a slightly staggered stance (one foot marginally ahead of the other). On the start command, the participant rose as quickly as possible — using the hands on the thighs or the chair for assistance if needed — walked briskly around the cone (either direction was permitted), and returned to a fully seated position. Timing stopped only when the participant was fully seated.
(Less than 5.3 seconds, and shorter is better in men.)