Regular exercise has a broad and beneficial effect on people, from improving general health to more specific effects such as feeling more energetic, better mood, increased endurance, weight loss, better control of blood sugar and improved heart health.
The heart is a muscular pump, pushing blood to different parts of the body. Its pumping action can be strengthened by exercise. However, exercise can also have other effects. For instance, in experiments with HIV-negative people, aerobic exercise (brisk walking, hiking, gardening, cycling, dancing, jogging, swimming, playing sports, strenuous yoga), resistance training (lifting weights) or a combination of both forms of exercise can do the following:
- improve circulation
- improve control of blood sugar
- improve levels of lipids (cholesterol and triglycerides) in the blood
- increase muscle mass
- decrease fat mass
Small studies have suggested that exercise can also be beneficial for HIV-positive people.
The Saturn Study
Researchers in the U.S. conducted a 96-week placebo-controlled study of the lipid-lowering drug rosuvastatin (Crestor). A sub-study of Saturn explored the impact of unsupervised exercise (as reported by participants). The Saturn researchers found that participants who reported to have engaged in "at least two and a half hours of moderate-intensity exercise per week were likely to experience lower levels of inflammation and [improved cardiovascular health]." Two and a half hours of exercise per week is equivalent to about 22 minutes each day.
All participants in Saturn were taking combination anti-HIV therapy (ART) and had undetectable or low viral loads in their blood. Further details about Saturn will appear later in this issue of TreatmentUpdate.
Researchers assessed participants' physical activity using surveys that had been previously developed and validated in other studies. The surveys asked about many different types of physical activity and how much time was spent on each activity.
Additionally, blood samples were collected for analysis on a regular basis.
A total of 119 participants completed surveys for the exercise sub-study. Overall, participants taking rosuvastatin reported engaging in more exercise than participants on placebo.
Physical activity was associated with improved measures of overall health. However, statistically significant improvement of the following assessments occurred only in statin users who also exercised:
- decreased levels of fatty tissue around the heart
- decreased levels of inflammation
- decreased levels of the chemical messenger IL-6 (interleukin-6; other studies have found that elevated levels of IL-6 are associated with an increased risk for inflammation and unfavourable events, including cardiovascular disease and reduced survival)
Researchers found that participants who did two and a half hours of moderate exercise each week were "likely to experience lower levels of inflammation and [had arteries that became more flexible]."
Thus, exercise has an important role to play in reducing excess inflammation.
Although the heart is chiefly thought of as a muscular pump, it keeps some fatty tissue as a store of energy. In people with cardiovascular disease, this fatty layer becomes larger, perhaps too large relative to the size of the heart. In the present study, participants who used a statin and who exercised lost greater amounts of this fatty layer compared to people on placebo who also exercised.
Bear in Mind
This exercise sub-analysis does have shortcomings, such as the following:
- The time that participants actually spent on exercise was not supervised. Sometimes people in studies may over-report socially desirable activities. However, in this placebo-controlled study there seemed to be clear benefits that only accrued to people who exercised and who used a statin. So it would appear that, on the whole, people who reported a significant amount (two and a half hours per week) of moderate exercise did have measurable changes in inflammation and in their hearts.
The research team encourages additional studies of exercise in HIV-positive people. The team suggests that such studies consider "objective measures of exercise, including activity monitors and heart rate monitors."
Such future studies need to have more women involved, as men comprised nearly 80% of the participants in Saturn.
HIV and cardiovascular disease -- CATIE fact sheet
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