The Shackelford Treadmill Protocol And Its Predictive Equations Accurately Assess VO2max In Multiple Chronic Diseases

INTRODUCTION: Maximal volume of oxygen consumption (VO2max) is a key mortality predictor and exercise prescription component, making the selection of an appropriate VO2max protocol essential, especially for populations at risk of premature death (chronic diseases). The Shackelford protocol (SP) was originally designed for cancer survivors, as its gradual progression accounts for cancer-related toxicities, but cardiopulmonary (CP), neurological (NE), metabolic (MET), and renal (RL) diseases may encounter similar side effects. Due to this, programs working with these populations are beginning to adopt the SP due to the gradual increase in intensity, resulting in better VO2max assessments and mortality risk prediction. However, the SP and its VO2 predictive equations have not been validated in these other populations. PURPOSE: To examine the validity of SP and its equations in CP, NE, MET, and RL. METHODS: 46 subjects (12 CP, 8 NE, 17 MET, 9 RL) performed the SP using gas analysis to measure true VO2max. Estimated VO2max was calculated via the ACSM walking/running equations from the same test. True VO2max was confirmed by meeting one of the following: < 10 beats per minute of age predicted max heart rate, rate of perceived exertion >8, respiratory exchange ratio > 1.1, or VO2 plateau with increased intensity. True vs estimated VO2max for all subjects was measured via a T-test. A Kruskal-Wallis Test compared differences between all groups, and a Wilcoxon Signed Rank test determined differences within each group. Significance was set at p < 0.05. RESULTS: For all subjects, no significant differences in VO2max (ml/kg/min) occurred between true (30.4 + 8.8) and estimated (29.7 + 7.9). Within each group, true and estimated VO2max for CP (32. 1 + 5.6 vs. 33.2 + 6.9), NE (30.8 + 9.1 vs 29.3 + 2.9), MET (28.2 + 4.5 vs 28.4 + 5.4), RL (29.5 + 8.1 vs 26.7 + 3.6) did not differ (p > 0.05). Between groups, true VO2max did not significantly differ (p = 0.75). CONCLUSION: SP and its equations provide valid VO2max’s for CP, NE, MET, and RL. Its gradual progression accounts for common side effects of fatigue, dyspnea, muscle weakness, and edema, leading to higher and more accurate VO2max values. It offers a standardized protocol that ensures valid VO2max measurements across diverse populations, suggesting its applicability beyond cancer survivors.