Proportional Internal Work-a New Parameter of Exercise Testing in Study of Health in Pomerania (SHIP)

This study assessed if the cost to initiate exercise termed proportional internal work (PIW) was related to cardiovascular disease risk factors, ventilatory parameters and mortality. The results suggest that PIW is a cardiopulmonary exercise test parameter that is related to cardiovascular disease risk and all-cause mortality. Purpose:Cardiopulmonary exercise testing usually requires a maximal exhaustive effort by the patient and is time consuming. The purpose of this study was to assess whether the cost to initiate exercise termed proportional internal work (PIW) was related to cardiovascular disease (CVD) risk factors, ventilatory parameters, and mortality.Methods:We used data from population-based Study of Health in Pomerania. A total of 2829 (49.5% female) study participants with a median age of 52 (42-62) yr were included. Standardized questionnaires were used to assess CV risk factors. The cardiopulmonary exercise testing was performed using a modified Jones protocol. Regression models adjusted for sex and age were used to relate PIW with CVD risk factors and ventilatory parameters. The PIW was calculated by the following formula: (Oxygen uptake at rest - Oxygen uptake without load)/Vo2peak) x 100. Cox regression analysis was used to relate PIW and all-cause mortality.Results:We identified a nonlinear association between PIW and percent predicted Vo2peak. Women had a 2.96 (95% CI, 2.61-3.32) greater PIW than men. With each year of age and every point in body mass index, the PWI increased by 0.04 (95% CI, 0.03-0.05) and 0.16 (95% CI, 0.12-0.20), respectively. After adjustment for age, sex, smoking, and body mass index, a 1-point greater PIW was associated with a 5% higher risk to die (HR = 1.05; 95% CI, 1.01-1.07).Conclusions:The PIW is a new cardiopulmonary exercise testing parameter related to CVD risk and all-cause mortality. Future studies should assess the prognostic relevance of PIW for CVD prevention.

Automated summary

This study found that the cost to initiate exercise (PIW) is related to cardiovascular disease risk and all-cause mortality. PIW can be used as a new parameter in cardiopulmonary exercise testing to assess the prevention and prognosis of cardiovascular disease.