Effect of a Supervised Aerobic Exercise Training Program and Ginkgo biloba Extract on Metabolic Parameters and Functional Capacity in HIV-Infected Subjects

1. Introduction

An increase in the life expectancy of people living with HIV (PLWH) due to antiretroviral therapy (ART) has led to an increase in the burden of non-communicable diseases in this population[1]. PLWH have a high prevalence of obesity-related comorbidities, including dyslipidemia, type 2 diabetes mellitus (T2DM), hypertension, and chronic kidney disease[2]. The risk of cardiovascular disease (CVD) is 2-fold higher in PLWH,[3] and non-AIDS-related mortality rates are largely attributable to CVD[4].

Weight gain with contemporary ART based on integrase strand transfer inhibitors (INSTI)-containing regimens and tenofovir alafenamide (TAF) has been well documented [5,6,7]. The proportion of metabolically unhealthy individuals is higher in HIV-infected people with excessive weight and central obesity [8].

Studies have shown that physical activity (PA) has multiple health benefits for PLWH, including cardiovascular health[9], functional capacity[10], improvements in metabolic parameters[11], body muscle strength[12], body composition, [13] and quality of life (QoL)[14]. However, it has been reported that PA is lower in HIV-infected than in most other populations with chronic diseases, and more than half of PLWH do not meet the physical activity recommendations of the World Health Organization (WHO) of at least 150 minutes of moderate-intensity physical activity per week[15].

Cardiometabolic disease management strategies, including the use of medicinal herbs, have been used worldwide. Ginkgo biloba (GKB), an herb used in traditional Chinese medicine for thousands of years, has high medicinal value because it contains flavonoids, treptene lactones, and phenolic compounds[16]. GKB has various properties, including antioxidants, free radical scavenging, membrane-stabilizing, anti-inflammatory, anti-platelet activating factors, antihypertensive, vasodilatory, cardioprotective, neuroprotective, anti-apoptotic, and anticancer activities[16].

It is a well-known plant that is used to treat atherosclerosis, ischemic heart disease, dementia, cerebrovascular insufficiency, hypertension, and peripheral arterial occlusive disease[17,18,19]. Experimental and clinical studies have reported metabolic benefits in hypertriglyceridemia and hypoglycemic properties; therefore, GKB supplementation has been used to treat dyslipidemia and to prevent or treat T2DM[20,21,22].

Considering the increased prevalence of metabolic abnormalities in PLWH, we investigated the effect of an exercise training (ET) program alone or in combination with supplementation of GKB or statins in this population.

2. Materials and Methods

2.1. Design and Approval of the Study

This was a single-center, randomized, double-blind, placebo-controlled, parallel group study, with a three-arm group, conducted in Guadalajara, Jalisco, Mexico, in accordance with the ethical principles of the World Medical Association for Medical Research involving human subjects. This study was approved by the Ethics Committee of the Hospital Civil de Guadalajara (no.165/21) and was registered at ClinicalTrials.gov (identifier NCT06403787). The purpose of the study was explained to the participants and written informed consent was obtained before screening and data collection.

The eligibility criteria for the intervention groups were as follows: HIV-infected men aged 18-55 years on ART with coformulated bictegravir, emtricitabine, and tenofovir alafenamide, with at least six months of undetectable HIV viral load, CD4⁺ T cell count >200 cells/µL, and mixed dyslipidemia with two or more abnormal findings: total cholesterol ≥200 mg/dL, LDL-c ≥100 mg/dL, HDL-c ≤40 mg/dL, and triglycerides ≥150 mg/dL. The exclusion criteria were active hepatitis B and C infection, heavy alcohol use (≥15 drinks per week), known hypersensitivity to Ginkgo biloba extract or statins, and use of any dietary supplement within 30 days of study enrollment.

2.2. Randomization and blinding

After eligibility was confirmed, the patients were randomized into three groups (allocation ratio 1:1:1) using computer-generated random numbers to receive GKB extract 120 mg QD, atorvastatin 20 mg QD, or placebo (figure 1).

2.3. Procedures

All subjects participated in a supervised aerobic ET program 3-5 times per week for 12 weeks. Exercise intensity gradually increased; in the first 4 weeks, the intensity was 50-60% heart rate maximum (HRmax), and in the next 8 weeks, it increased to 60-80%. The duration of the exercise was 50 min per session; each exercise session included a 5-minute warm-up and 5 minutes cool-down period with stretching exercises. The sessions were conducted in a gym close to the center and were supervised by an exercise researcher.

2.4. Measurements

At the baseline visit and after 12 weeks, functional capacity, including VO_2max (middle step test), strength (back-leg and hand-held dynamometers), flexibility (Sit and Reach test), and balance (single-leg stance balance test), in addition to anthropometric measurements were evaluated in all participants, who were given a diary to record medication adherence and report adverse events, and received dietary counseling. All patients attended visits every 4 weeks to the center to evaluate adherence to the ET program, intake of the study medication, reporting of adverse events, changes in functional capacity through the previously mentioned physical tests and anthropometric measurements, and completion of the IPAQ short-version questionnaire.

Laboratory tests to assess the metabolic profile were performed in a fasting state at the baseline visit and week 12, including hematology, glucose, creatinine, urea, BUN, total cholesterol, LDL-c, HDL-c, VLDL-c, triglycerides, total, direct, and indirect bilirubin, total protein, albumin, AST, ALT, GGT, alkaline phosphatase, insulin, and HbA1c. The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated according to Matthews et al.[23], a value >2.5 was used as a cutoff for insulin resistance;

2.5. Statistical Analysis

The sample size for this pilot study considered recommendations when there was no information from previous research to base sample calculations[24]. The Shapiro-Wilk test was used to analyze the normality distribution of the quantitative variables. Non-normally distributed data were analyzed using nonparametric statistical tests. Quantitative variables are expressed as mean ± standard deviation (SD) or median (interquartile range); qualitative variables are expressed as frequency (n) and percentage (%). One-way ANOVA or Kruskal-Wallis test was used to compare quantitative variables between the three study groups. Friedman’s test was used to compare final and initial intragroup values ​​. Data was analyzed using SPSS version 20. Statistical significance was set at p <0.05.

3. Results

Twenty-eight HIV-infected patients were included in this study. All the patients underwent supervised ET. Ten patients received placebo (ET + Placebo), 10 received GKB extract (ET + GKB), and 8 patients received statin (ET + Statin). When comparing the baseline demographic variables between the study groups, significantly higher levels of ALT, urea, and BUN were found in the ET + Statin group than in the ET + GKB group (p<0.05). No other significant differences were observed between groups (Table 1).

No significant differences were observed in the anthropometric variables after 12- week intervention between the three groups. The effect on metabolic variables after 12- week intervention showed a significant decrease in total cholesterol in the group receiving statins compared to that in the other two groups (p <0.05) (Table 2).

Body fat decreased significantly by 2-3% at the end of the 12-week intervention in all three groups relative to their baseline values (p<0.05) (figure 2a). Waist circumference (WC) also decreased significantly in participants receiving statins compared with baseline values (p= 0.009).

Total cholesterol and LDL-c were significantly decreased in the ET + statin group at the end of the study (p= 0.04 and p= 0.007, respectively) compared to baseline values (figure 2b), while HbA1c (figure 2c) and the HOMA index (figure 2d) were significantly decreased in the ET + GKB group (p= 0.03 and p= 0.02, respectively) compared to baseline values, and a significant increase in CD4+ T cell mean was observed in the ET + Placebo group (p=0.005) compared to baseline values.

A significant increase in cardiorespiratory capacity (VO_{2 max}) from their baseline values was observed in all three groups (p<0.001) after 12-weeks of intervention from their baseline values, in addition to a significant increase in back strength in the ET + GKB group (p= 0.02) and flexibility in the ET + statin group (P=0.02) (Table 3).

4. Discussion

The prevalence of chronic comorbidities in PLWH is high[25], and a strategy that has demonstrated health benefits in this population is PA[13]. There is evidence that PA reduces the risk of chronic diseases including obesity, T2DM, osteoporosis, breast and colon cancer and coronary artery disease in the general population[26]. Studies on supervised and unsupervised PA have shown greater benefits when the activity is supervised[27], and supervised PA has been reported to improve functional capacity [28] and adherence in PLWH[29]. We found a significant reduction in total body fat with supervised aerobic ET in all groups, which is in accordance with other studies that have reported improvements in body fat and body composition in PLWH with supervised aerobic PA[30,31]. Resistance exercise and combined aerobic and resistance exercise have also demonstrated benefits in terms of body fat, body composition, muscle strength, cardiorespiratory fitness, and quality of life in PLWH[28,32,33,34].

PA has also shown multiple metabolic benefits including improvements in insulin resistance, blood lipid levels, and hepatic fat content, regardless of weight loss[35]. A reduction in the risk of diabetes with significant improvements in glucose and insulin, both fasting and postprandial, HOMA-IR, weight, systolic blood pressure, and triglycerides was found in a 6-month intervention study with diet and physical activity in PLWH and impaired fasting glucose[36]. Similarly, advanced glycation products (proteins or lipids that become glycated as a result of exposure to reduced sugars) are implicated in the risk of the development of cardiovascular disease, diabetes, and other chronic diseases, and triglycerides were significantly decreased after a supervised training program of combined exercise (aerobic, resistance, and flexibility) for three months in physically inactive HIV-infected subjects[11]. In our study, we did not find a decrease in HOMA-IR or HbA1c in the ET+P group compared to the ET+S group; however, in the ET+GKB group, there was a significant improvement in both parameters.

A significant increase in VO₂ peak was found by Mutimura et al. in a 6-month study of supervised PA in PLWH[30], which is in line with our findings of a significant increase in VO₂ max observed in the three groups, indicating an improvement in cardiorespiratory fitness through the 12-week ET program. However, one study in older HIV-infected men found that only high-intensity aerobic exercise and not moderate-intensity aerobic exercise for 16 weeks was associated with a significant improvement in cardiorespiratory fitness (VO₂ peak)[37].

Several studies in HIV − and HIV+ subjects have demonstrated that exercise has anti-inflammatory effects by reducing inflammatory biomarkers, including IL-1β, IL-6-IL-8, TNFα, and improving immune function[32,38,39]. Nevertheless, a study of PA in PLWH found no differences in the markers of immune activation (CD38 and HLA-DR) or inflammation (IL-6 and TNF-α), although exercise was self-prescribed[40]. There are contradictory results regarding the improvement in immune function associated with physical activity in PLWH. Smith et al. found no significant changes in CD4⁺ T cell counts in an RCT after 12 weeks of aerobic exercise in PLWH, [31] whereas Brito-Neto et al. found that a 12-week resistance training program resulted in a significant increase (15.7%) in CD4⁺ T cell counts[33]. A significant increase in the number of CD4⁺ T cells was observed in the ET + P group.

The prevalence of T2DM among PLWH is up to four times higher than that among the general population in some regions of the world[41]. Several risk factors have been identified for the development of T2DM in older PLWH, including duration of HIV infection, lower CD4⁺ T cell nadir, long duration of HIV infection, use of older-generation antiretroviral therapy, high BMI, and arterial hypertension[42].

GKB exerts antidiabetic effects by increasing insulin expression and sensitivity. GKB extract increases pancreatic β-cell function [43]and improves insulin sensitivity by enhancing IRS-2 transcription[44], as IRS-2 is a crucial element in insulin signaling, and studies have found that a deficiency of IRS-2 causes insulin resistance[45]. We found a significant decrease in insulin resistance (HOMA-IR) and HbA1c levels in our study of non-diabetic PLWH; therefore, its usefulness as a dietary supplement for the prevention of diabetes should be considered. Aziz et al. found a significant decrease in HbA1c, fasting serum glucose, BMI, WC, and VAI in T2DM subjects ineffectively treated with metformin, to whom GKB extract supplementation was added for six months.[46] The effects on BMI, WC, and VAI have been associated with an increase in lipolysis induced by the GKB extract[47].

A pilot study of subjects with metabolic syndrome (MS) found a significant decrease in hs-CRP and HOMA-IR, as well as in other inflammation and oxidative stress biomarkers and nanoplaque formation, with the administration of GKB extract over 2 months. The HOMA-IR score and nanoplaque formation were significantly correlated in this study[48]. HOMA-IR predicts incident symptomatic CVD independent of classic risk factors and several blood biomarkers; therefore, insulin resistance should be an important target not only for reducing or treating T2DM, but also for reducing cardiovascular risk[49]. HOMA-IR has been correlated with increased CVD/total mortality in both the diabetic and non-diabetic populations[50,51]. Furthermore, in the MESA study, HOMA-IR was found to predict the incidence and progression of coronary artery calcification, although not independently of MetS status[52].

Experimental studies with GKB extract have observed other metabolic benefits, including reduction in body adiposity in diet-induced rats, restoration of obesity-induced insulin signaling impairment,[53] inhibition of adipogenesis, regulation of lipid metabolism, body weight reduction in mice,[54] and a decrease in adipocyte volume from obese rats to dimensions equivalent to adipocytes from non-obese rats, suggesting a potential anti-obesogenic effect of GKB[55]. Moreover, the GKB extract exerts several lipid-lowering effects, including decreased cholesterol absorption, inactivation of HMG-CoA, and improvement of essential polyunsaturated fatty acids[56]. The favorable effects of GKB on lipids have been observed in both experimental and clinical studies[57,58]. We did not find any relevant changes in the lipid parameters of our patients in the GKB group, probably because of the short study duration. However, the statin-treated group showed significant changes in total cholesterol and low-density lipoprotein cholesterol levels. These results agree with those of a study carried out by Zanetti et al., who found that ET, statin use, and the combination of both decreased total cholesterol, LDL-c, TG, CRP, IL-1-β, and carotid intima-media thickness compared with no intervention in PLWH. Furthermore, the combination of ET + statins showed a significant decrease in total cholesterol, TG, LDL-C, inflammatory markers (IL-1 β, IL-6, IL-8), and carotid intima-media thickness and a significant increase in HDL-c compared to the individual use of statins and ET[59]. Our study has limitations, including the small sample size, it was carried out in a single center and a single country, and only males were enrolled; therefore, the results cannot be generalized to other regions or to females. Analysis of inflammatory biomarkers would have strengthened the results of this study.

5. Conclusions

HIV infection is now a treatable chronic disease, and it is a concern that about half of PLWH are physically inactive. Our study demonstrated that supervised physical activity improves body fat and cardiorespiratory capacity. This effective non-pharmacological intervention should be encouraged in PLWH to engage them in physical activity. In contrast, GKB extract is an inexpensive supplement with effects on insulin resistance in PLWH and could be used in the prevention and add-on treatment of T2DM. Further large-scale studies are required to confirm these findings.