Blood lipids of cardiac patients after acute exercise on land and in water.

Objective: To compare the effect on lipids of a single bout of high-intensity interval training performed on land and in water in a group of cardiac patients involved in an intensive cardiac rehabilitation program.

Design: Single-group, quasiexperimental, crossover design.

Setting: Swimming pool at a cardiac rehabilitation hospital in Australia.

Participants: Ten men, ages 55 to 77 years, with ischemic heart disease.

Intervention: Subjects performed 15 minutes of interval arm ergometer work at 65% to 75% of attained heart rate, as determined by treadmill testing on land and in water on the same day. Each patient had his own exercise prescription.

Main Outcome Measures: At each endurance phase, the number of revolutions and rate-pressure product (RPP) during the final minute of work were taken. Fasting bloods were taken at baseline and after maximum exercise, and lipid profiles were determined; differences were analyzed by paired t test.

Results: No significant differences in revolutions or RPP were observed, which indicates that workload and heart work were similar in all experiments. There were no significant changes in total, low-density lipoprotein cholesterol, triglyceride, or apolipoproteins A-I or B after exercise (paired t test). High-density lipoprotein cholesterol (HDL-C) was increased significantly by exercise on land. In 6 patients with low baseline HDL-C (<0.9 mmol/L), HDL-C was increased only on land.

Conclusions: A single bout of high-intensity interval training was more effective in improving HDL-C when performed on land than in water.