Exercise and HIV: What the Science Shows

by Tadd Lazarus, M.D.

Diet and exercise remain inexorably linked. So, it is both fitting and necessary that any focus on nutrition explore its relationship to exercise. A universal exercise regimen for HIV-positive individuals cannot be created. Rather, like any prescription, exercise must be tailored to the individualpis aptitude and fortitude. The following review of the recent literature in this area should help to bring readers up to date on the science of exercise in the setting of HIV infection.

In the article "Association between exercise and HIV disease progression in a cohort of homosexual men" (Mustafa T et al., Ann Epidemiol, 9(2): 127-31 1999 Feb) a group of 415 people (156 HIV-positive, 259 HIV-negative) were studied from a cohort of 851 homosexual men from New York City during the years 1985 to 1991. By 1991, 68 of the 156 HIV-positive people developed AIDS and 49 died with AIDS. If an individual reported that he exercised 3 or 4 times a week, he was considered to have exercised; less was considered nonexercise. Log CD4 count was modeled against the number of days to construct CD4 lymphocyte decline. The results showed that exercise (in the definition of the study) was associated with a slower progression to AIDS at one year. Exercise was also associated with slower progression to death with AIDS at one year. This suggests that the exercise had a protective effect close to the time it was assessed. Exercising three to four times a week had a stronger protective effect than daily exercise. Exercisers in the HIV-positive group showed an increase in CD4 count during one year by a factor of 1.7. The authors conclude that moderate physical activity may slow HIV disease progression.

This study started before antiretrovirals were available, and the observational period was over by the start of the antiretroviral era. Therefore, the study provides an interesting observational database. Because of its timing, it inadvertently controlled for antiretroviral therapy-no highly active or long active therapies were administered to the group, so the usual hodgepodge of trying to sort out drug effect from that of the exercise intervention was not introduced.

In "Moderate and high intensity exercise training in HIV-1 seropositive individuals: a randomized trial" (Terry L; Sprinz E; Ribeiro JP, Int J Sports Med, 20(2): 142-6 1999 Feb) the authors acknowledge that "HIV-infected individuals are frequently active, but guidelines for exercise in this population lack scientific support, since studies on the effects of exercise training on immunologic variables of HIV-1 positive individuals have shown conflicting results." In this study, exercise capacity, immunologic markers (CD4, CD8 and CD4:CD8 ratio), anthropometric measurements, and depression scores were evaluated to compare the effects of two intensities of aerobic exercise on HIV-1 seropositive people. Twenty-one healthy subjects (14 men, 7 women), who were HIV positive with CD4 cell counts of greater than 200 cell/mm(-3), had been exercise-inactive for at least 6 months; they completed a 12-week exercise training program. The program consisted of 36 sessions of one hour duration, three times a week. The subjects were divided into two groups: a moderate-intensity group (60 plus or minus 4% of maximal heart rate) or a high-intensity group (84 plus or minus 4% of maximal heart rate). Exercise capacity, as measured by treadmill time, increased significantly in both the moderate- and high-intensity groups, but the high-intensity group increased by a significantly larger increment (p<0.01). The authors conclude that HIV-seropositive individuals that participate in moderate- and high-intensity exercise programs are able to increase their functional capacity without any detectable changes in immunologic variables, anthropometric measurements or depression scores. This article is important because it clearly shows that HIV-positive individuals can safely participate in moderate-to-high intensity exercise without immunologic or anthropometric deterioration.

In "Cardiopulmonary and CD4 cell changes in response to exercise training in early symptomatic HIV infection" (Perna FM et al, Med Sci Sports Exerc, 31(7):973-9 1999 Jul), the authors set out to assess the effects of a 12-week, laboratory-based aerobic exercise program on cardiopulmonary function, CD4 cell count, and physician-assessed health status. They studied these factors in 28 symptomatic pre-AIDS HIV-infected individuals, and measured the degree to which ill health followed discontinuation of exercise. The researchers recorded participantspi responses to a graded exercise test, physician-assessed health status, and CD4 cell counts. These were determined at baseline and at a 12-week follow-up for participants randomly assigned to exercise or control conditions, and reasons for exercise noncompliance were recorded. The authors found that approximately 61% of the participants assigned to the exercise group complied with the exercise program-compliance was defined as attendance at more than 50% of assigned exercise sessions. Analyses of exercise relapse data indicated that obesity and smoking status, but not exercise-associated illness, were the traits that distinguished compliant from noncompliant exercisers. As would be expected, compliant exercisers significantly improved leg power as well as physiological measures including peak oxygen consumption, oxygen pulse, tidal volume and ventilation. No group differences in health status were found. Most importantly, a significant interaction effect indicated that noncompliant exerciserspi CD4 cell counts decreased significantly (18%), whereas compliant exerciserspi CD4 cell counts significantly increased (13%; P<0.05).

How can knowledge of exercise be used in a pragmatic manner to assist HIV-positive patients with lipodystrophy, i.e. the syndrome of body fat redistribution? Lipodystrophy has been described as a gain in abdominal and trunk fat, along with a decline in facial and limb fat. It is one of the most devastating complications of care that has been identified to date. In "A pilot study of exercise training to reduce trunk fat in adults with HIV-associated fat redistribution (Roubenoff R et al. AIDS, 13(11):1373-5 1999 July 30) the authors note that increased abdominal fat may predispose these patients to hypertension, diabetes, and coronary artery disease. The study examined whether exercise training could reduce trunk fat in men with fat redistribution. Ten men with increasing abdominal girth participated in a 16-week pilot study of progressive resistance training with an aerobic component. The study subjects trained in a community health club three times a week. Total body lean and fat mass, and trunk fat mass, were assessed by dual-energy x-ray absorptiometry (DXA-the "gold standard" in non-invasive body composition measurement). After 16 weeks of exercise, strength increased for three of the four exercises tested: leg press, leg extension and chest press (not seated body row). There was a significant decline in total body fat by 1.5 kg; most of this decline occurred in trunk fat, which decreased by 1.1 kg. Weight, lean mass and bone mineral density as measured by DXA did not change. No adverse effects were seen from the training. The authors conclude that exercise training may reduce trunk fat mass in HIV-positive men with fat redistribution.

This study provides an important glimpse into the potential ability of exercise to have targeted metabolic effects without the prescription of additional drugs. It is tempting to speculate that adding an anabolic agent to this exercise program would result in a greater normalization of fat distribution, but that will require further clinical trials. N

Tadd Scott Lazarus, M.D. has been in practice for nearly a decade as an HIV primary care physician. Dr. Lazarus is an attending physician at St. Vincentpis Hospital and Medical Center of New York City and is an assistant professor of clinical medicine at New York Medical College where he participates in primary care education of medical students.