Physical Performance and Mortality in Obesity: Evidence Summary
Direct Answer to Your Question
The evidence demonstrates that high physical fitness substantially reduces mortality risk in people with obesity, and fit individuals with obesity achieve mortality rates equal to or lower than unfit individuals without obesity—but the specific performance thresholds you're asking about (gait speed, grip strength, SPPB, frailty scores) have not been adequately studied in obesity-specific populations to provide definitive hazard ratios or crossover thresholds.
What the Evidence Actually Shows
Mortality Reduction in Active vs. Inactive Adults with Obesity
Active adults with obesity demonstrate a 21% lower risk of all-cause mortality (HR: 0.79,95% CI: 0.74-0.84) and 24% lower cardiovascular mortality (HR: 0.76,95% CI: 0.66-0.87) compared to inactive adults with obesity 1
Physical activity attenuates many health risks associated with obesity, and this protective effect is often stronger in obese individuals than in those of normal weight 2
The largest mortality benefits occur in the least active individuals who begin exercising, with even 1.5 hours per week of moderate-to-vigorous activity producing a 20% reduction in all-cause mortality 3
Fit Obese vs. Unfit Lean: The Critical Comparison
Active obese individuals have lower morbidity and mortality than normal weight individuals who are sedentary 2
In the European EPIC study involving 334,161 participants, avoiding all physical inactivity would theoretically reduce all-cause mortality by 7.35% (95% CI: 5.88%, 8.83%), while avoiding obesity (BMI >30) would reduce mortality by only 3.66% (95% CI: 2.30%, 5.01%) 4
Physical inactivity and low cardiorespiratory fitness are as important as overweight and obesity as mortality predictors 2
The Nuance: Not All Studies Agree
A critical Swedish cohort study of 37,633 men challenges the "fit-fat" hypothesis:
Compared to lean-active men, the mortality risk ratios were: obese-active men (HR: 1.44), lean-inactive men (HR: 1.54), and obese-inactive men (HR: 1.81) 5
After excluding early deaths and confounders, overweight-to-obese active men still had HR: 1.65 compared to lean-active men 5
This study does not support the hypothesis that higher physical activity completely compensates for excess mortality associated with obesity 5
The Problem: Wrong Measures Being Studied
Your question asks about non-aerobic physical performance measures (gait speed, grip strength, chair rise, balance, SPPB, frailty), but the available evidence focuses almost exclusively on aerobic capacity and general physical activity levels:
The meta-analysis by Kodama et al. examined maximal aerobic capacity and found a pooled RR of 1.73 (95% CI: 1.50-1.99) for lower vs. higher aerobic capacity, but this was not stratified by obesity status 6
Cardiorespiratory fitness shows an 11% reduction in all-cause death and 18% reduction in cardiovascular death for each 1-MET increase, but again, obesity-specific thresholds are not reported 7
Peak VO₂ thresholds exist for cardiovascular disease patients: >22 mL/kg/min achieves HR of 0.39 for cardiac deaths and 0.45 for all-cause deaths compared to <15 mL/kg/min 7, but these are not obesity-specific
Practical Performance Thresholds (Best Available Evidence)
Activity Volume Targets for Mortality Reduction in Obesity
>6 MET-hours per week produces a 26% reduction in all-cause death or hospitalization, compared to 18% reduction with >4 MET-hours per week 7
This translates to approximately 150-300 minutes per week of moderate-intensity aerobic activity or 75-150 minutes of vigorous-intensity activity 3, 7
Muscle-strengthening activities involving all major muscle groups on at least 2 non-consecutive days per week provide additional benefits 3
Cardiorespiratory Fitness Targets
Target peak VO₂ >22 mL/kg/min for optimal mortality protection, which places individuals at lower absolute risk than sedentary individuals without cardiovascular disease 7
Achieving 15-22 mL/kg/min represents an intermediate threshold (HR: 0.62 for cardiac deaths, 0.66 for all-cause deaths compared to <15 mL/kg/min) 7
For women specifically, achieving <5 METs is associated with significantly increased risk of death and ischemic heart disease events 7
Critical Clinical Caveats
The "Obesity Paradox" Complicates Interpretation
Once heart failure develops, obesity (particularly class I obesity, BMI 30-35 kg/m²) is associated with improved survival compared to normal BMI—a J-shaped curve exists 6
This paradox makes it difficult to establish universal thresholds, as the relationship between obesity, fitness, and mortality may reverse in certain disease states 6
Measurement Challenges in Obesity
BNP levels are less helpful in diagnosing heart failure in obese patients because they can have normal or minimally elevated levels even with acute decompensated heart failure 6
Hemodynamic confirmation may be needed more often in obese than lean patients to confirm clinical diagnoses 6
The Evidence Gap You're Highlighting
The specific non-aerobic performance measures you asked about (gait speed, grip strength, chair rise, balance tests, SPPB, frailty scores) have not been systematically studied in obesity-specific cohorts with mortality outcomes:
No studies in the provided evidence report hazard ratios for these specific measures stratified by obesity status
The frailty literature suggests that low frailty scores (high physical fitness) protect against mortality even with substantial pathological burden, but obesity-specific thresholds are not established 8
Physical activity and fitness have body mass index-independent prognostic value for all-cause mortality 7, but the exact performance thresholds where fit obese individuals achieve mortality equivalence with unfit lean individuals remain undefined for non-aerobic measures
Evidence-Based Recommendation
Given the current evidence, prioritize achieving >6 MET-hours per week of physical activity (approximately 150-300 minutes of moderate-intensity or 75-150 minutes of vigorous-intensity aerobic activity weekly) in adults with obesity to reduce all-cause mortality by approximately 21-26% 1, 7. This level of activity appears to achieve mortality rates comparable to or better than sedentary individuals without obesity, though one high-quality Swedish study suggests residual excess risk may persist 5, 4.
The specific non-aerobic performance thresholds (gait speed, grip strength, SPPB, frailty scores) that achieve mortality equivalence between fit obese and unfit lean individuals have not been established in peer-reviewed literature—this represents a significant research gap that prevents answering your question with the precision you're seeking.