---
title: The Health NestEgg | NestEgg Health Risk Model v8.0
url: https://www.nestegghealth.com/health-nestegg/
description: The NestEgg Health Risk Model v8.0: how weekly exercise and Challenges build a Health NestEgg, mapped onto published research, limits stated.
---

The Health NestEgg

# Build a nest egg of health.

*(like a pension. the deposit is exercise.)*

People spend their working lives building a financial nest egg. The Health NestEgg is the other one: a health asset built through sustained exercise that compounds over time. Our Health Risk Model shows what the published evidence predicts it is worth.

[Try the Health NestEgg calculator](https://support.nestegghealth.com/tools/health-nestegg-calculator)

## What the model projects

All cause mortality risk reduction at full maturity, NestEgg Health Risk Model v8.0.

−41% Level 1 + strength 150 Exercise Points a week plus two strength sessions.

−46% Level 4 + strength 300 Exercise Points a week plus two strength sessions.

Modeled from observational hazard ratios (Arem et al. 2015; Momma et al. 2022; Saeidifard et al. 2019). Associations, not measured NestEgg outcomes. See the limitations below.

## Two ways exercise protects you.

*(both evidence based. both measured by NestEgg.)*

Mechanism 1

### Exercise dose

Sustained weekly exercise at the clinical guideline dose, built through weekly Health Deposits : 150 Exercise Points plus two strength sessions a week (Level 1 + strength). It reduces chronic disease risk through inflammatory, metabolic and endocrine pathways.

Evidence: Arem et al. 2015 (661,137 adults); Momma et al. 2022.

Mechanism 2

### Fitness capacity

Cardiorespiratory fitness (VO₂max), pushed up by the higher intensity blocks that NestEgg Challenges naturally produce, four weeks at a time. It reduces mortality through cardiac output, mitochondrial density and vascular remodeling.

Evidence: Singh et al. 2024 (20.9 million observations); Kodama et al. 2009; Mandsager et al. 2018.

### The formula

Health NestEgg = 1 − (1 − exercise dose protection) × (1 − fitness bonus protection)

The two mechanisms work through separate biological pathways, so they combine multiplicatively, the standard method for independent risk modifiers. Exercise dose protection is the risk reduction for your deposit level multiplied by its maturity. Fitness bonus protection is modeled at 3% per Challenge in the past 12 months, a deliberately conservative assumption (see limitation 3).

## Nine conditions. One habit.

*(risk reduction by weekly deposit level.)*

### Risk reduction by deposit level

Percentage reduction in risk compared with inactivity, from the model's hazard ratios.

| Condition | Level 1 aerobic | Level 1 + strength | Level 4 + strength |
| --- | --- | --- | --- |
| All cause mortality | 31% | 41% | 46% |
| Cardiovascular disease | 25% | 38% | 44% |
| Type 2 diabetes | 26% | 39% | 47% |
| Depression | 25% | 35% | 37% |
| Dementia | 28% | 37% | 43% |
| Colon cancer | 19% | 31% | 38% |
| Breast cancer | 10% | 24% | 27% |
| Heart failure | 24% | 37% | 43% |
| Stroke | 26% | 39% | 44% |

Source: NestEgg Health Risk Model v8.0, Mechanism 1. Level 1 aerobic all cause mortality HR 0.69 (95% CI 0.67 to 0.70). Combined aerobic and strength values are HR aerobic × HR strength (for all cause mortality 0.69 × 0.85 = 0.587), checked against Saeidifard et al. 2019.

### Level 1 + strength

The most accessible combination delivers close to the maximum protection.

All cause mortality 41%

Type 2 diabetes 39%

Stroke 39%

Cardiovascular disease 38%

Dementia 37%

Heart failure 37%

Depression 35%

Colon cancer 31%

Breast cancer 24%

Why strength matters: Level 1 aerobic plus two strength sessions (HR 0.587) matches or beats Level 4 aerobic alone (HR 0.63).

## It compounds.

*(early gains come fast. full adaptation takes patience.)*

### How your Health NestEgg grows

Scenarios from the model's Health NestEgg calculator.

| Scenario | Exercise dose | Fitness bonus | Health NestEgg |
| --- | --- | --- | --- |
| Level 1 + strength, 52 weeks, no Challenges | 26% | 0% | 26.0% |
| Level 1 + strength, 52 weeks, 2 Challenges | 26% | 6% | 30.4% |
| Level 1 + strength, 52 weeks, 4 Challenges | 26% | 12% | 34.9% |
| Level 1 + strength, 104 weeks, 4 Challenges | 35% | 12% | 42.8% |
| Level 4 + strength, 104 weeks, 4 Challenges | 40% | 12% | 47.2% |

[Run your own numbers in the full calculator](https://support.nestegghealth.com/tools/health-nestegg-calculator)

### Maturity

Exercise dose protection matures over about four years: maturity = 1 − e −weeks/52 .

10 weeks 17%

26 weeks 39%

52 weeks 63%

104 weeks 86%

156 weeks 95%

208 weeks 98%

The four year curve reflects how long the body takes to adapt: cardiovascular remodeling (12 to 24 months), metabolic adaptation (2 to 3 years), cancer risk reduction (3 to 5 years) and musculoskeletal adaptation (2 to 4 years).

## Why the Challenge matters.

*(Challenges push the ceiling up. deposits stop the floor collapsing.)*

Competitive four-week Challenges get people training harder than they would on their own, and higher intensity training builds cardiorespiratory fitness faster than steady moderate exercise (Poon et al. 2024).

Fitness gained in a Challenge fades within weeks of stopping completely. Keeping up moderate exercise between Challenges preserves most of it, so the next Challenge builds from a higher floor (Mujika and Padilla 2000, 2001). That is why a Season runs four Challenges a year.

### Fitness and mortality

All cause mortality hazard ratio compared with low fitness, Mandsager et al. 2018 (122,007 patients).

| Fitness level | Hazard ratio |
| --- | --- |
| Below average | 0.51 |
| Above average | 0.38 |
| High | 0.27 |
| Elite | 0.20 |

Each 1 MET gain in fitness is associated with 13% to 17% lower all cause mortality (Kodama et al. 2009; Singh et al. 2024). Each unit of VO₂max gained is associated with about 45 more days of life (Sørensen et al. 2018).

## Why NestEgg's data fits the model.

*(the research measured minutes, intensity and strength. so do we.)*

- Weekly exercise minutes at moderate to vigorous intensity. NestEgg scores every workout from heart rate, so it can tell a slow walk from vigorous exercise.

- Strength training frequency. Strength sessions are identified by workout type and counted separately.

- Consistency. Week by week records show sustained exercise, not just a sign up.

- Guideline alignment. Weekly totals map onto the WHO guideline, so we can report who meets it each week.

To our knowledge, NestEgg is the only workplace program capturing these variables at the individual level every week. That claim has not been independently audited.

## The small print, in big print.

*(every model has limits. here are ours.)*

- Observational evidence. The hazard ratios come from observational cohort studies, not randomized trials. They are associations and should not be read as causal effects.

- Selection bias. NestEgg participants choose to take part. Published trial evidence (Song and Baicker 2019) suggests self selection could inflate apparent risk reduction by 20% to 40%.

- The fitness bonus is an assumption. The 3% per Challenge figure is conservative and not yet measured. NestEgg has not yet quantified the VO₂max gain from a four-week Challenge, and will calibrate it with Challenge data.

- Population averages. Hazard ratios are pooled across ages and both sexes. Absolute benefit varies by age and sex. Age and sex specific versions are planned.

- Limited strength evidence for some conditions. For depression, dementia and cancers, conservative default strength values of 0.85 to 0.87 are used until condition specific research is published.

- Combined confidence intervals are approximate. Intervals for aerobic plus strength are approximated from the component intervals.

- The maturity curve is a modeling choice. The 52 week time constant is informed by biological timelines but has not been fitted to NestEgg participant data.

- Competitive claims are unaudited. Claims about NestEgg's measurement compared with other programs are made to the best of our knowledge.

NestEgg is a community exercise program for the workplace, not a medical service. This model describes populations, not individual medical advice.

## Key sources

- Arem H, et al. Leisure time physical activity and mortality. JAMA Internal Medicine, 2015. 661,137 adults, 14.2 year median follow-up.

- Momma H, et al. Muscle strengthening activities and mortality. British Journal of Sports Medicine, 2022.

- Saeidifard F, et al. Resistance exercise and mortality. Preventive Medicine, 2019.

- Singh B, et al. Cardiorespiratory fitness and mortality. British Journal of Sports Medicine, 2024. 20.9 million observations, 199 cohorts.

- Kodama S, et al. Cardiorespiratory fitness and mortality. JAMA, 2009. 33 studies, 102,980 participants.

- Mandsager K, et al. Cardiorespiratory fitness and long term mortality. JAMA Network Open, 2018. 122,007 patients.

- S rensen L, et al. VO₂max and longevity. Journal of the American College of Cardiology, 2018.

- Kokkinos P, et al. Fitness and mortality in US veterans. Journal of the American College of Cardiology, 2022.

- Poon E, et al. High intensity interval training and cardiorespiratory fitness. Scandinavian Journal of Medicine and Science in Sports, 2024.

- Mujika I, Padilla S. Detraining. Sports Medicine, 2000 and 2001.

- Song Z, Baicker K. Effect of a workplace wellness program. JAMA, 2019.

The full NestEgg Health Risk Model v8.0 draws on 41 sources and is available on request. [Ask for the full model](https://www.nestegghealth.com/contact/?topic=model).