In the HIV positive population the benefits of PA and exercise have been studied with varying results. Studies have focussed on a host of interventions, which include aerobic exercise only, progressive resistance training only, a combination of aerobic and progressive resistance exercise and other modalities like yoga and T‘ai Chi. Exercise has also been found to be an effective self-managed non-pharmacological therapy in HIV positive patients and has been shown to be a safe form of therapy for persons
35 infected with HIV, with benefits including the improvement in CD4 count, improving functional work capacity, muscular strength and muscular endurance (Bopp, et al., 2003:77).
Research has found that a minimum of 30 minutes of moderate intensity cardiovascular exercise on 5 days of the week or 20 minutes of vigorous intensity cardiovascular exercise on three or more days of the week, as well as resistance exercise on two to three days per week can result in numerous benefits, including weight management in the general population (Garber, et al., 2012:1338). The American College of Sports Medicine (Durstine & Moore, 2002:176) recommends that moderate intensity cardiovascular exercise (60-75% of maximum heart rate) is prescribed to PLWHIV. This exercise should be done for duration of 20-60 minutes, but not exceeding 90 minutes, on three to five days per week. The prescribed exercise should take into account immunological markers and medical treatments. The ACSM provides no recommendations regarding progressive resistance training.
Ross, Freeman, and Janssen (2000:165) indicated that exercise over a prolonged period brings about changes in central and total body fat, and thus results in changes in body composition. In a study conducted on 18 ART-treated HIV-infected men, Yarasheski, Tebas, Stanerson, Claxton, Marin, Bae, Kennedy, Tantisiriwat and Powderly (2001:134) found that a 16-week progressive resistance training programme, conducted four times per week at an intensity ranging between of 50% to 85% of 1 repetition max, resulted in an increase in body weight, an increase in whole body lean mass and improved strength. They also noted a reduction in circulating triglyceride levels. It was proposed that the exercise-induced increase in lean mass was responsible for the clearance of triglycerides. Since the metabolic complications resulting from HIV infection include muscle wasting and hypertriglyceridemia, the results of this study suggest that progressive resistance exercise, together with dietary interventions could manage the metabolic complications of HIV infection (Yarasheski, et al., 2001:137).
36 Roubenoff and Wilson (2001:1811) found that an eight week progressive resistance training programme, conducted three times a week resulted in improved strength and increases in lean muscle mass in both wasted (n = 6) and non-wasted (n = 19) HIV positive men and women (Roubenoff & Wilson, 2001:1813). Additionally, Roubenoff and Wilson (2001:1814) found that their progressive resistance exercise programme resulted in improvements in self-reported physical function in specifically their participants with muscle wasting syndrome, as measured by the Medical Outcomes Study (MOS) Short Form-36 (SF-36).
Dudgeon, Phillips, Bopp and Hand (2004:95), in their review of the effects of exercise interventions in HIV disease, suggested that low to moderate exercise has no negative effect on CD4 cell count or viral load, nor does it increase susceptibility to opportunistic infections, while Smith, Neidig, Nickel, Mitchell, Para and Fass (2001:693) also found that a combination of progressive resistance training, or strength training and aerobic exercise had no effect on CD4 and viral load. However, LaPerriere, et al. (1991:S53) found that an aerobic exercise programme increased CD4 count. A literature review by LaPerriere, et al. (1997:S56) revealed: no decline in CD4 cell counts and a trend toward an increase in the number of CD4 cells, with more significant increases seen in the earlier stages of the disease. CD4 count has also been found to improve by following a balanced diet (Hendricks, Mwamburi, Newby & Wanke, 2008:1584) and through the use of micronutrient supplements (Kaiser, Campa, Ondercin, Leoung, Pless & Baum, 2006:523). Mutimura, Stewart, Crowther, Yarasheski and Cade (2008c:381) found that PLWHIV who were treated with HAART and who had body fat redistribution significantly improved their overall quality of life following a six month aerobic exercise program, without compromising immune function. Rojas, et al. (2003:440) found that exercise improved quality of life and psychological indices in HIV infected persons.
While research has been conducted addressing the benefits of exercise for PLWHIV the research is not conclusive as these studies are plagued by high attrition rates and poor compliance and adherence to the exercise interventions. The modes of exercise prescribed in the intervention studies also vary extensively. In a number of the intervention studies the variability of frequency, intensity and duration of the prescribed
37 exercise programmes make it difficult to compare the results across the intervention studies. In previously conducted exercise intervention studies, sample sizes and unmatched control groups reduced the ability of generalise the study results (Dudgeon, et al., 2004:84).
2.6.2.1. Aerobic Exercise
Prior to the use of HAART, a study by Birk, MacArthur, Lipton and Levine (2002:23) indicated that an aerobic exercise program, which consisted of 40 minutes of continuous aerobic exercise, conducted three times per week for the duration of 12 weeks, resulted in either no change, or a decline in body mass, CD4 count and maximal oxygen consumption. The exercise intensity for this intervention study was set at 60% - 70% of maximal oxygen uptake, which was measured by heart rate. The study participants, five HIV positive men with advanced HIV, had high compliance rates, with only one of the five participants attending less than 50% of the exercise sessions. Additionally, it was found that in these participants, exercise did not bring about the same changes in blood lipids as is experienced in the HIV negative population. These participants had advanced levels of immunosuppression as they had a mean CD4 count of 274 cells/mm³ (SD = 7.0). The level of immunosuppression could be one reason why the exercise did not result in physiological changes. The authors also suggested that the exercise intensity may have been insufficient (Birk, et al., 2002:23).
Research has documented the incidence of decreased aerobic capacity in PLWHIV. Whether this is attributed to the HIV infection itself or to the use of HAART is still uncertain. However, the benefits of aerobic exercise for PLWHIV have been very well documented. Moderate intensity aerobic exercise has been found to improve both functional aerobic capacity and cardiovascular fitness. Aerobic capacity is determined by the body‘s ability to utilise oxygen while doing physical work. A low functional aerobic capacity impairs the ability to perform physical work. Hand, Phillips, Dudgeon, Lyerly, Durstine and Burgess (2008:1070) found that a six week long moderate aerobic exercise program resulted in improvements in functional aerobic capacity, of around 20% (n = 30) for their male participants and 24% (n = 10) for their females, with no difference being noted between those being treated with HAART and those not on
38 HAART. The improvements found in this cohort (n = 40) indicated that the functional aerobic impairment which was found prior to the intervention was not present in these participants following the intervention program.
Another study by Dudgeon, Phillips, Durstine, Burgess, Lyerly, Davis and Hand (2010:564) found that HIV infection and treatment resulted in an increase in catabolic hormones and inflammatory cytokines, while moderate aerobic and progressive resistance, as prescribed for healthy HIV negative individuals by the ACSM, resulted in an increase in the anabolic hormones, growth hormone and testosterone, and a decrease in the catabolic hormone cortisol and tumor necrosis factor. These findings suggest that moderate intensity aerobic exercise and progressive resistance exercise done for 30 minutes each, as prescribed by the ACSM may have implications for numerous HIV-related comorbidities, including muscle wasting, body composition changes and cardiovascular disease (Dudgeon, et al., 2010:566). Furthermore, their study found that the combination of moderate intensity aerobic and resistance exercise has a greater effect on the magnitude of change in variables as well as the number of variables which are changed when compared with low intensity aerobic exercise alone.
2.6.2.2 Progressive resistance exercise
In the pre-HAART era, muscle wasting in PLWHIV was seen as an indicator of disease progression and of mortality. O‘Brien, Tynan, Nixon and Glazier (2008:649) conducted a systematic literature review on the effects of resistance training in PLWHIV. Their findings indicated that progressive resistance training, done on three days per week, at an intensity of 50% and 80% of 1 repetition maximum (1RM) which can be described as the maximum amount of weight which can be lifted in 1 repetition, was safe for PLWHIV. While it did not result in changes in the CD4 count, it had beneficial effects on body composition (including body weight and girths), muscular strength, cardiovascular fitness and improvements in psychological outcomes like self-perception.
Lindegaard, Hansen, Hvid, van Hall, Plomgaard, Ditlevsen, Gerstoft and Pedersen (2008:3867) investigated the effects of strength and endurance training on insulin sensitivity and body composition in 20 sedentary HIV positive men with lipodystrophy.
39 All participants were HAART-treated and had suppressed VL (<20 copies/mL). The participants exercised three times per week for 16 weeks, with each session lasting between 45-60 minutes and were randomised into either endurance exercise or progressive resistance exercise groups. The endurance exercise consisted of 35 minutes of unspecified exercise performed at 50% to 100% of maximal oxygen consumption (VO2 max). The progressive resistance exercise consisted of exercises for
all large muscle groups and the exercise intensity increased on a weekly basis. Participants exercised at an intensity of between 50% and 80% of 1RM. The results of the study showed that both strength and endurance training improved insulin sensitivity, but that only strength training led to an overall decrease in fat mass.
2.6.2.3 Alternative exercise therapies
PLWHIV have made use of alternative therapies to manage the side-effects of both HIV and antiretroviral use, and to improve health and well-being (Cho, Ye, Dobs & Cofrencesco, 2006:475; Cade, Reeds, Mondy, Overton, Grassino, Tucker, Bopp, Laciny, Hubert, Lassa-Claxton & Yarasheski, 2010:380). Studies have been conducted to assess the benefits of neuromuscular exercise in HIV-positive persons. This form of exercise integrates functional activities like yoga and T‘ai Chi.
Galantino, Shepard, Krafft, LaPerriere, Ducette, Sorbello, Barnish, and Condoluci (2005:1086) investigated the benefits of group exercise interventions, with both aerobic exercise and T‘ai Chi as the mode of exercise in PLWHIV with a CD4 count <200 cells/mm³, which constitutes an AIDS diagnosis. They found that overall quality of life improved as a result of the social interaction resulting from a group training environment. In HIV infection functional ability, or the ability to function effectively in daily life, like going to work, driving a car, or even caring for oneself is usually impaired in HIV infection due to muscle wasting syndrome and the subsequent loss of metabolically active lean muscle tissue (Mindt, Cherner, Marcott, Moore, Bentley, Esquivel, Lopez, Grant, Heaton, & the HNRC Group, 2003:122). Galantino, et al., 2005:1091 found improvements in functional ability as a result of T‘ai Chi and aerobic exercise.
40 In another study, yoga was found to reduce both systolic and diastolic blood pressure values in a cohort of symptomatic HIV-infected patients who were HAART treated. These changes occurred without any negative effect on CD4 count and viral load (Cade, et al., 2010:384).