 |
|
|
| |
Exercise Program Improves Aerobic Function and Endurance in Older HIV+ Men
|
| |
| |
3rd International Workshop on HIV and Aging, November 5-6, 2012, Baltimore
Mark Mascolini
A 16-week high-intensity aerobic exercise program improved aerobic function and exercise endurance more than a low-intensity program in a small randomized study of HIV-positive men older than 50 [1]. Both programs significantly improved walking distance.
Compared with the general population, people with HIV infection run a higher risk of age-related conditions such as heart disease, osteoporosis, and frailty--all of which may be worsened by a sedentary lifestyle. University of Maryland researchers hypothesized that aerobic exercise training in older HIV-positive men could increase exercise endurance and that high-intensity training would be needed to increase aerobic capacity.
The investigators randomized 22 sedentary men to high-intensity exercise or to low-intensity exercise. All men were 50 or older, had not had an AIDS illness in the past 6 months, and were taking antiretrovirals for at least 6 months. No men were homeless. Both groups exercised 3 times a week for 16 weeks in a research gym. An exercise physiologist oversaw the training and encouraged men to maintain outside activity and not to change their diet.
High-intensity exercise consisted of 4 weeks of treadmill training with an exercise target of 30 minutes at 40% to 60% of heart-rate reserve, then 12 weeks of treadmill training with a target of 60 minutes at 75% to 80% of heart-rate reserve. The low-intensity group walked 1 mile on an indoor track at a self-selected pace and then stretched. The researchers measured exercise endurance in both groups as time on the treadmill and aerobic capacity as oxygen utilization at peak exercise (peakVO2).
Two men dropped out of the high-intensity group and 3 out of the low-intensity group, so 9 high-intensity men and 7 low-intensity men completed the 16-week program.
Median age of men in both groups stood at 57; most were African American. Median CD4 count measured 481 in the high-intensity group and 469 in the low-intensity group. Because of the small sample size, the groups were unbalanced in weight and related variables. Low-intensity men averaged 97 kg and high-intensity men 77 kg. Respective averages in related measures were 34% and 22% body fat, 190 and 108 cm(2) visceral adipose tissue, 133 and 113 mg/dL fasting glucose, and 154 and 67 pmol/L insulin. Average triglycerides were higher in the low-intensity group (221 versus 117 mg/dL), but low- and high-density lipoprotein cholesterol did not differ significantly between the two groups.
During the 16-week program, peakVO2 rose 17% in 9 men remaining in the high-intensity group, from an average 1.89 L/min to 2.12 L/min (P = 0.02). But peakVO2 did not change in 16 weeks in 7 men in the low-intensity group (average 1.73 L/min to 1.75 L/min, P = 0.9).
Time on the treadmill increased significantly over the 16 weeks both in the high-intensity group and the low-intensity group. In high-intensity men average time rose from 11.7 to 14.3 minutes, a 25% improvement (P = 0.02). In low-intensity men average time climbed from 11.0 to 12.1 minutes, an 11% gain (P = 0.04). Ambulatory function also improved significantly in both groups. The high-intensity group added 62 meters (12%) to their 6-minute walk (P = 0.01), while the low-intensity group added 54 meters (11%) (P = 0.01).
Aerobic training had no significant impact on lipids, glucose, or insulin, and exercise did not change weight, waist circumference, percent body fat, or total lean mass measured by DEXA (all P > 0.4). These measures did not differ significantly between the two study groups. There were small, nonsignificant improvements in markers of inflammation in the high-intensity group, including a 2% drop in interleukin 6, a 2% drop in TNF-alpha, a 7% drop in interleukin 8, and a 10% fall in high-sensitivity C-reactive protein.
The researchers called for further study of aerobic exercise combined with weight loss and resistance training, with an eye toward improvements in measures of lipodystrophy, sarcopenia (loss of muscle mass and strength), or osteoporosis. Identifying mechanisms of increased aerobic capacity in HIV-positive people, the investigators noted, could inform the design of an exercise-effectiveness trial.
Reference
1. Oursler K, Sorkin J, Ryan A, et al. Effect of aerobic exercise training in older HIV-infected patients. 3rd International Workshop on HIV and Aging. November 5-6, 2012, Baltimore. Abstract O_11.
|
| |
|
|
|
|
|
