Validation of accelerometer cut-points for physical activity intensities in people with coronary heart disease.

Design This validation study for accelerometer cut-point development in people with coronary heart disease will be conducted in Australia over 18-months. Eligible participants will be required to attend the University of Canberra in Bruce for up to 2 hours and complete a peak incremental treadmill test and some activities of daily living, allowing an adequate rest in between tests to minimize fatigue. The treadmill test will be completed first, followed by the activities of daily living. During all tests participants will be required to wear a face mask for gas analysis (measurement of oxygen consumption). No further involvement is required. Gas analysis data from the treadmill and activity testing will be compared with the accelerometer data to develop equations (cut points) to classify physical activity intensity. Accelerometry: An ActiGraph triaxial commercial accelerometer will be used to objectively assess physical activity during the treadmill test and the activities-of-daily-living. Participants will be asked to wear the accelerometer around their waist, over their right hip throughout the testing, as well as around their non-dominant wrist on the dorsal aspect. The data collected by the accelerometer, counts, will be compared to oxygen consumption (VO2). Peak treadmill test: Direct measurement of aerobic fitness (oxygen consumption, VO2) will be determined via an incremental exercise test on a treadmill. Participants will begin walking at an easy level and the treadmill speed and/or gradient will be increased incrementally to volitional or symptom-limited exhaustion. The participants will be fitted with a facemask to enable the analysis of expired gases, measuring VO2. Prior to the treadmill test participants will complete a seated resting-metabolic-rate assessment. Expired gases will be collected continuously and individual resting-metabolic-rate will be determined. During the treadmill test, participants will also be fitted with a 12-lead ECG and blood pressure cuff, and their ECG and blood pressure will be monitored by a medical practitioner with advanced cardio-pulmonary resuscitation (CPR) qualifications throughout the test. Activities of daily living (ADL): Following the treadmill test participants will complete a series of ADL simulations including; watching television (sedentary), seated stretching, standing stretching, floor sweeping and stepping in place (higher intensity). Each ADL will be completed for 5-minutes according to standardized instructions, with 10-minutes seated rest between tasks or until heart rate returns to resting level. Throughout activity simulations participants will be fitted with a facemask to enable the analysis of expired gases. Other outcome measures are: - video recording of lower limbs to accurately record steps completed throughout the treadmill test - height and weight measures - completion of a demographic and clinical questionnaire. 164 participants with coronary heart disease will be recruited to this trial, including a small cohort of participants that also have class I-II heart failure (n=20). For the data analysis, the study sample (n=164) will be randomly split into a learning set and an independent validation set (2:1), allowing for a cross validation statistical procedure using a sub-sample of participants. No participants will be required to undergo further testing.