Given an abstract, indicate which of the provided candidate titles (Option1 and Option2) best describes it (respond with the text of the title, not option1/2).

Example input: Abstract: Some patients converted from ventricular fibrillation to organized rhythms by defibrillation-trained ambulance technicians (EMT-Ds) will refibrillate before hospital arrival. The authors analyzed 271 cases of ventricular fibrillation managed by EMT-Ds working without paramedic back-up. Of 111 patients initially converted to organized rhythms, 19 (17%) refibrillated, 11 (58%) of whom were reconverted to perfusing rhythms, including nine of 11 (82%) who had spontaneous pulses prior to refibrillation. Among patients initially converted to organized rhythms, hospital admission rates were lower for patients who refibrillated than for patients who did not(53% versus 76%, P = NS), although discharge rates were virtually identical (37% and 35%, respectively). Scene-to-hospital transport times were not predictively associated with either the frequency of refibrillation or patient outcome. Defibrillation-trained EMTs can effectively manage refibrillation with additional shocks and are not at a significant disadvantage when paramedic back-up is not available. 
 Which is the apt title for the abstract? option1: Refibrillation managed by EMT-Ds option2: Maintenance of compliance in a small diameter arterial prosthesis.
Example output: Refibrillation managed by EMT-Ds
Example explanation: The abstract is about refibrillation and it is also mentioned in the abstract that it is managed by EMT-Ds. So it is an apt title.
Q: Abstract: Aerobic exercise is now a common form of recreational exercise among young women. In a previous study, more than a third of a group of young mothers volunteering blood samples to establish a creatine kinase (CK) reference range for Duchenne muscular dystrophy (DMD) carrier detection regularly participated in aerobic exercise programs. Aerobic exercise programs include eccentric exercises. As eccentric exercise is known to produce a delayed CK peak, this study was carried out to determine the effect of aerobic exercise on serum CK activities. The postexercise serum CK activity peak was monitored in 15 young women (age range 20-23 years) following aerobic exercise classes (45 minutes on 3 consecutive days). Peak values at 24-48 hours following the last class ranged from 90 to 3473 U/liter, or 1.55 to 34.71 times resting values. It is concluded that aerobic exercise programs should be excluded in order to obtain accurate resting serum CK values for muscle disease diagnosis. 
 Which is the apt title for the abstract? option1: The effect of aerobic exercise on serum creatine kinase activities. option2: Multiphasic MR imaging: a new method for direct imaging of pulsatile CSF flow.
A:
The effect of aerobic exercise on serum creatine kinase activities.