K25 - Development of a Comprehensive, Equipment-Free, Fitness Assessment

Introduction: : Non-communicable diseases, often resulting from physical inactivity, represent a major source of global morbidity. Improving and tracking fitness across various domains including balance, strength, endurance, and cardiorespiratory fitness (CRF) is associated with improved longevity, healthspan, and functional capabilities. However, current fitness assessments are often qualitative, episodic, require specialized equipment, or are designed for specific populations. There is a need for a comprehensive, quantitative, and accessible fitness assessment battery that can be performed without specialised equipment across a broad adult population to effectively track fitness factors. This study aimed to: (1) determine the feasibility of a series of bodyweight exercises in a general adult population; (2) compare performance on bodyweight exercises to established, instrumented reference measures across multiple fitness domains (balance, upper body, lower body, core, CRF, and flexibility) ; and (3) develop a comprehensive, equipment-free, active assessment battery based on these findings.

Materials and

Methods: : Research subjects (N=152, 81 Male, 71 Female, age range 21-59 years) were recruited after screening for exercise readiness using the Physical Activity Readiness Questionnaire (PAR-Q). All protocols were IRB approved. In a single session, participants performed a series of bodyweight exercises and established reference tests targeting balance, upper/lower body strength and endurance, core capacity, cardiorespiratory fitness (CRF), and flexibility. Reference measures included the three stage balance test (balance), handgrip dynamometry (upper body), knee extension dynamometry (lower body), 1-minute crunches (core), the YMCA 3-minute step test (CRF), and instrumented sit-and-reach (flexibility). A subset of participants (n=15) also performed the Bruce graded protocol and indirect calorimetry (CRF). Corresponding bodyweight exercises evaluated included the one-legged stance (OLS; balance), maximum push-ups and maximum floor-triceps-dips (upper body), squat holds (lower body), plank holds (core), paced run-in-place and paced burpees (CRF), and a stand-and-reach test (balance). Statistical analyses (t-tests, Pearson correlations, with Bonferroni corrections, p< 0.05 considered significant) were used to assess performance differences, compare bodyweight vs. reference measures, and evaluate novel CRF estimation models.

Results, Conclusions, and Discussions:: Most participants successfully performed all reference and bodyweight exercises, though push-ups proved most challenging (8/152 unable). Significant positive correlations emerged between several bodyweight exercises and reference measures, notably push-up repetitions with grip strength (r=0.52) and stand-and-reach with sit-and-reach scores (r=0.83) (p < 0.001 for both). However, isometric exercises like squat and plank holds exhibited significant ceiling effects, limiting their discriminatory ability for correlation analyses in this population. This suggests dynamic, isotonic repetition-based exercises, such as crunches are superior for quantitative assessment while offering greater real-world relevance.
For cardiorespiratory fitness (CRF), models estimating VO2​max from 3-minute run-in-place and burpee tests (MAE 1.29 mL/kg∗min), using Step Test VO2​max estimates as labels, were effective. VO2​max derived from the equipment-free, paced run-in-place exercise correlated significantly with VO2​max measured via indirect calorimetry (r=0.75, p=0.05, n=7), while the burpee test did not show a significant correlation (r=0.51, p=0.30, n=7). The run-in-place test was preferred by participants and avoided the upper-body fatigue associated with burpees, making it a suitable candidate for a comprehensive battery. Significant sex- and age-based performance differences were also observed across multiple tests.
This study validates that (1) a curated battery of equipment-free, bodyweight exercises can feasibly assess key components linked to health and fitness in an adult population; (2) isotonic, repetition-based exercises were superior for quantitative assessment compared to static holds, which suffered ceiling effects; accessible equipment-free methods for estimating CRF, such as a 3-minute run-in-place test, were validated against well-established reference tests, and all passing body weight exercises were assembled into an assessment battery; and (3) the proposed battery, which included stand and reach (flexibility), OLS (balance), run in place (CRF), push ups (upper body), crunches (core), and squat reps (lower body), offers a practical, low-cost, scalable, and quantitative approach for longitudinally tracking functional performance changes. This facilitates earlier detection of fitness declines, can inform individualised exercise recommendations, and has potential for automation via smartphone technology, thereby empowering wider populations to quantitatively monitor and improve factors related to healthspan and longevity.

Acknowledgements and/or References (Optional):: We thank the members of the Google Research team for many illuminating discussions. Funding for this effort was provided by Google, LLC.