Cardio vs. Lifting: Which Lowers Biological Age More?

Cardiorespiratory fitness (CRF) and resistance training (RT) influence biological age through distinct, complementary biological pathways [9, 12, 18]. High cardiorespiratory fitness demonstrates a robust, dose-dependent association with reduced biological age acceleration across large population cohorts [18]. In contrast, resistance training produces pronounced improvements in specific metabolic components of biological age models, including glycemic control and insulin sensitivity [9, 12]. The main caveat is that composite biological age algorithms rely on broad panels of blood biomarkers, meaning that neither modality alone optimizes every underlying physiological system as effectively as concurrent training [9, 15, 18].

How Composite Biological Age Is Calculated

Unlike first-generation epigenetic clocks that were trained simply to predict chronological calendar age, second-generation clinical models such as PhenoAge and GrimAge were developed to predict healthspan, disease onset, and all-cause mortality [7].

The clinical PhenoAge algorithm uses chronological age alongside nine routine blood biomarkers [5, 6]:

• Albumin: Reflects liver function and nutritional status [5]
• Creatinine: Measures renal clearance and kidney function [5]
• Glucose: Captures resting metabolic health [5]
• C-Reactive Protein (CRP / hs-CRP): Quantifies systemic low-grade inflammation [5, 6]
• Lymphocyte Percentage: Reflects immune system distribution and immunosenescence [5, 6]
• Mean Corpuscular Volume (MCV): Measures red blood cell size [5, 6]
• Red Cell Distribution Width (RDW): Evaluates red blood cell size variability (using percentage-based RDW rather than RDW-SD) [5, 6]
• Alkaline Phosphatase (ALP): Reflects liver and bone turnover [5, 6]
• White Blood Cell (WBC) Count: Quantifies overall immune and inflammatory activity [5, 6]

These biomarkers capture systemic multisystem decline across physiological inflection waves, which proteomics studies indicate accelerate around ages 44 and 60 [8]. Multimodal interventions combining exercise with diet, sleep, stress management, and supplementation have demonstrated that PhenoAge can be reversed by an average of 3.23 years within 8 weeks [8].

Cardiorespiratory Fitness and Phenotypic Age

Cardiorespiratory fitness, commonly measured via maximal oxygen uptake (VO2 max) or estimated through treadmill testing, displays an inverse relationship with phenotypic biological age [18]. In an analysis of 3,069 adults aged 20–49 in the National Health and Nutrition Examination Survey (NHANES), maintaining high cardiorespiratory fitness was associated with a 42% reduction in the odds of phenotypic age acceleration [18]. Conversely, individuals with impaired CRF showed a 1.46-year increase in PhenoAge relative to peers with normal fitness levels [18].

This relationship is further exacerbated by body composition: in adults older than 29 years, obesity significantly interacts with low CRF to compound biological aging acceleration [18]. These biological age reductions align with long-term epidemiological cohorts such as the Aerobics Center Longitudinal Study and the Veterans Affairs Study, which observed 13% to 15% reductions in all-cause mortality for every 1-MET increase in exercise capacity [18].

Aerobic training—particularly near-maximal protocols such as high-intensity interval training (HIIT) performed at ≥90% VO2 max or ≥77% maximum heart rate—stimulates cellular rejuvenation [14]. HIIT interventions promote PGC-1alpha activation, driving mitochondrial biogenesis, enhancing mitophagy, restoring gene-specific DNA methylation, and increasing telomerase activity [12, 14]. These adaptations directly translate to lower biological aging rates, such as reductions in the DunedinPACE pace-of-aging metric [12].

Resistance Training and Metabolic Biomarkers

While aerobic capacity heavily influences systemic mortality risk scores, resistance training exhibits superior efficacy in altering key metabolic blood biomarkers included in biological age calculations [9, 12]. In an 8-week randomized trial of inactive middle-aged men (BMI 27.66 ± 0.91 kg/m²), resistance training and concurrent training produced significantly larger reductions in fasting blood glucose and insulin resistance than aerobic training alone [9].

Resistance exercise achieves this by stimulating muscle protein synthesis through transient mTOR signaling, counteracting sarcopenia and metabolic decline without causing the pathological continuous mTOR activation seen in cellular aging [12]. Beyond glucose regulation, resistance and concurrent training also drove greater reductions in systolic blood pressure compared to standalone aerobic training in the same cohort [9]. However, aerobic training demonstrated superior efficacy for reducing central adiposity as measured by waist-to-hip ratio [9].

Functional muscular strength also serves as a strong clinical surrogate for biological vitality [19, 22]. In multi-domain functional models, handgrip strength and Timed Up and Go (TUG) scores heavily weight biological age algorithms and correlate strongly with the Levine mortality score (r = 0.90) [22]. Phenotypic grip strength is associated with lower frailty and fewer functional limitations over multi-decade follow-ups, though genetic variants (such as loci in ATP2A1, FTO, SLC39A8, and BDNF) explain only a fraction of this variance, highlighting the primary role of environmental training status [19, 20, 21]. Furthermore, longitudinal data show that individuals with accelerated epigenetic aging suffer steeper subsequent declines in walking speed and grip strength over time [23].

Systemic Inflammation and Myokine Signaling

Systemic inflammation, represented primarily by hs-CRP in composite panels, is responsive to both modalities [5, 15]. A meta-analysis of 38 randomized controlled trials in 2,557 healthy adults demonstrated that long-term exercise training (aerobic, resistance, and multicomponent) significantly decreases CRP, IL-6, and TNF-α [15].

These anti-inflammatory effects depend on duration and intensity: programs lasting longer than 12 weeks and conducted at moderate intensity yield the largest reductions in circulating CRP, whereas excessively high exercise intensity can attenuate CRP reductions [15]. Both modalities also stimulate the release of protective myokines, such as Meteorin-like protein (Metrnl/Subfatin), which modulates inflammatory immune pathways, facilitates muscle repair via Stat3/IGF-1 signaling, and supports cardiac endothelial integrity [17].

Practical Comparisons for Training

When evaluating how each modality influences composite biological age scores:

• Cardiorespiratory Training: Drives systemic cellular protection, telomere preservation, and mitochondrial turnover, while conferring population-level protection against PhenoAge acceleration [12, 14, 18].
• Resistance Training: Directly targets the metabolic and muscular drivers of biological age by improving fasting blood glucose, reversing insulin resistance, reducing resting blood pressure, and preserving functional strength [9, 12, 22].
• Concurrent Training: Optimizes the broadest array of PhenoAge inputs by simultaneously lowering fasting glucose, reducing systolic blood pressure, decreasing waist-to-hip ratio, and suppressing systemic inflammatory markers like CRP [9, 15].