Breakfast calcium and prior exercise in obesity

The study was a single-blind, within subject, cross-over trial. Each postprandial laboratory visit was separated by a 2-week interval. Prior to the trial, subjects were required to attend introductory classes to resistance exercises (RE) 3 times per week for 2 consecutive weeks to familiarize themselves to the equipment and to be assigned the appropriate exercise intensity. Subjects were given one week break between the introductory classes and the start of the trial. Subjects' meals prior to the exercise bout and the night prior to each postprandial visit were standardized. They received sachets of instant pasta meals to consume before the RE and frozen packs of rice and butter chicken to consume the night before each postprandial visit. The breakfast meal served at the postprandial visit was either high (high calcium breakfast, HCB) or low (low calcium breakfast, LCB) in dairy calcium. They were made up of full-cream milk, rolled oats, sultanas, white sugar and whipping cream. A calcium supplement, extracted from milk, was added to the HCB to increase its calcium content. LCB was served with the prior RE session. The nutritional composition of: HCB - 537.01mg calcium, 1318.7kJ, 13.9% energy from protein, 54.7% energy from carbohydrate, 30.7% energy from fat LCB - 257.25mg calcium, 1325.7kJ, 13.2% energy from protein, 55.5% energy from carbohydrate, 30.6% energy from fat RE consisted of 4 sets of 10 exercises (bench press, leg press, seated row, partial dead lift, bicep curls, calf raises, upright row, abdominal curl, fixed leg dumbbell lunge, shoulder shrugs), each performed at 10 repetition maximum. A rest period of 1 minute was given between each exercise throughout the training session in a circuit-type workout. The acute RE session was conducted once, 16 hours prior to an LCB postprandial visit. Subjects were randomized in either group A or B. Group A undertook the RE-LCB session first, followed by either LCB or HCB. If the 2nd postprandial visit was LCB, then the 3rd would be HCB and vice versa. Group B undertook the visits in the reverse order. Thus either LCB or HCB for the 1st and 2nd session and the RE-LCB session last. Since the trial is an acute study, there was no washout period required. After consuming the provided dinner meal, subjects maintained a 12-14 hr overnight fast. Subjects rested for 30mins before having their resting metabolic rate measured for 30mins and fasting blood sample drawn. Subjects were required to consume the respective breakfast within 15mins, then rested for 15mins. Indirect calorimetry measurements, to assess substrate oxidation and diet-induced thermogenesis, were carried out for 30mins on the hour for 5 hours. A blood sample was taken after each indirect calorimetry measurement.