PURPOSE: The practice of exercise prescription calculates the benefits of exercise on specific health outcomes according to the frequency, intensity, time, type, volume and progression of exercise. However, exercise prescription does not typically account for differences in injury risk associated with exercise training programs. The purpose of the present study was to calculate a novel effectiveness ratio (ER) to compare differences in cardiometabolic risk reduction alone and relative to injury risk between exercise interventions. METHODS: Data from two exercise studies (JAMA Pediatr. 2014;168:1006-14 and Br J Sports Med. 2009;43:825-31) were used to calculate the absolute value of the average percent (%) change in measured cardiometabolic risk factors (RF) alone and as an ER (% change in RF relative to the % of participants injured during training). RESULTS: In Study 1, 6 months of aerobic exercise (AE), resistance exercise (RE) and combined exercise (CE) training evoked similar (p =0.45) average reductions in RF (systolic and diastolic blood pressure, body mass index, and waist circumference) of 3.3±1.0, 2.3±1.0, and 2.8±1.3%, respectively. However, when normalized to injury rates, the ER of AE was significantly higher (0.8±0.2) than the ER of RE (0.3±0.1; p<0.01) and CE (0.3±0.1;p<0.01). In Study 2, 12 weeks of soccer (S) and running (R) training evoked similar (p=0.14) improvements in RF (systolic blood pressure, heart rate, low-density lipoprotein cholesterol and maximal oxygen uptake) of 11.0±3.9 and 7.0±2.6%, respectively. When normalized to injury rates, the ER of S was significantly higher than the ER of R (1.4±0.5 vs. 0.4±0.2;p<0.01). CONCLUSIONS: Examining the effectiveness of an exercise intervention by creating an ER (change in health outcome relative to the number of participants who were injured during training) demonstrates that certain modalities of exercise may be more beneficial for cardiovascular and metabolic health due not to their absolute impact on health alone but their favorable effect in relation to low likelihood of injury. Future research is needed to rigorously test use of the ER, but examining outcomes in exercise interventions with respect to both health improvement and injury rates may ultimately result in a more personalized, effective outcome for the patient.