Impaired oxygen on-kinetics in persons with human immunodeficiency virus are not due to highly active antiretroviral therapy

Walking endurance, muscle oxygen extraction, and perceived fatigability after overground locomotor training in incomplete spinal cord injury: A pilot study

Objective: The purpose of this study was to examine the effects of overground locomotor training (OLT) on walking endurance and gastrocnemius oxygen extraction in people with chronic cervical motor-incomplete spinal cord injury (SCI).Design: Prospective single-arm pre-post pilot study.Setting: Human Performance Research Laboratory.Participants: Adult men with traumatic chronic cervical SCI (n = 6; age = 30.8 ± 12.5).Intervention: Twenty-four sessions of structured OLT.Outcome measures: Walking endurance was determined during a constant work-rate time-to-exhaustion treadmill test. Normalized perceived fatigability was calculated by dividing subjective ratings of tiredness by walking time. Cardiorespiratory outcomes and muscle oxygen extraction were analyzed using breath-by-breath gas-exchange and near-infrared spectroscopy.Results: OLT resulted in large effects on walking endurance (1232 ± 446 s vs 1645 ± 255 s; d = 1.1; P = 0.045) and normalized perceived fatigability (5.3 ± 1.5 a.u. vs 3.6 ± 0.9 a.u.; d = 1.3; P = 0.033). Small-to-medium effects on absolute (2.8 ± 2.5 a.u. vs 4.2 ± 3.5 a.u.; d = 0.42; P = 0.035) and isotime (2.8 ± 2.5 a.u. vs 3.8 ± 3.0 a.u.; d = 0.33; P = 0.023) muscle oxygen extraction were also observed after OLT.Conclusion: These findings provide preliminary data supporting the potential for improved walking endurance, enhanced muscle O2 extraction, and reduced perceived fatigability in people with chronic cervical motor-incomplete SCI following the OLT program described in this study.

Effects of Exercise Interventions on Aerobic Capacity and Health-Related Quality of Life in People Living With HIV/AIDS: Systematic Review and Network Meta-Analysis

OBJECTIVE

Exercise is a recommended component of care for people living with HIV/AIDS; however, it is unclear which type of exercise is most effective. The purpose of this study was to investigate the relative effects of different types of exercise interventions on aerobic capacity measured by peak oxygen consumption (peak VO2) and health-related quality of life (HRQoL) in this population.

METHODS

For this systematic review and indirect-comparisons meta-analysis (network meta-analysis), different electronic databases were searched up to February 2020 for randomized controlled trials that evaluated the effects of different types of exercise interventions on peak VO2 and HRQoL of people living with HIV/AIDS. Mean differences, standardized mean difference (SMD), and 95% CI were calculated. Fixed- and random-effects Bayesian network meta-analysis were used to compare the relative effectiveness of the different exercise interventions.

RESULTS

Forty studies met the study criteria, reporting on a total of 1518 patients. When comparing the exercise interventions with usual care (control group) for the peak VO2 outcome, combined aerobic and resistance exercise was the highest ranked exercise intervention with an SMD of 4.2 (95% CI = 2.5 to 5.9), followed by aerobic exercise (SMD = 3.1; 95% CI = 1.4 to 5.1). Compared with aerobic exercise, resistance training, and yoga, combined aerobic and resistance exercise was the best exercise intervention to promote improvement on physical function, general health, mental health, and energy/vitality domains HRQoL.

CONCLUSION

The combined aerobic and resistance exercise was the highest ranked exercise intervention to improve peak VO2 and HRQoL. Combined aerobic and resistance exercise should be considered as a component of care for people living with HIV/AIDS.

Muscle Strength and Aerobic Capacity in HIV-Infected Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Physical impairment is highly prevalent in HIV-infected patients. We conducted a systematic review of published studies that included studies comparing muscle function in HIV-infected patients to matched healthy controls, and studies comparing aerobic capacity in HIV-infected patients with that observed in matched healthy controls.

DESIGN

Systematic review and meta-analysis.

METHODS

We searched for references on MEDLINE, SciELO, Cumulative Index to Nursing and Allied Health (CINAHL), and Scopus up to December 2017. Weighted mean differences and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed using the I test.

RESULTS

A total of 30 studies, covering 2148 healthy controls and 2161 HIV-infected patients, fulfilled the inclusion criteria. The average muscle strength and aerobic capacity were significantly lower in HIV-infected patients. Meta-analysis revealed moderate-quality evidence of weaker muscle strength and aerobic capacity in HIV-infected patients. A significant difference in lower-body strength of 1.07 (95% CI: 0.29 to 1.84) was found for participants in the healthy control group compared with HIV group. A significant difference in aerobic capacity (peak VO2) of 8.4 (95% CI: 4.8 to 12.0) was found for participants in the healthy control group compared with HIV group.

CONCLUSIONS

Muscle strength and aerobic capacity of HIV-infected patients are reduced in comparison with healthy controls. Additional studies are needed to define the best interventions to improve the physical function in HIV-infected patients.

Oxygen uptake on-kinetics before and after aerobic exercise training in individuals with traumatic brain injury

Objective: The high prevalence of fatigue among persons with traumatic brain injury (TBI) may be related to poor cardiorespiratory fitness observed in this population. Oxygen uptake on-kinetics is a method of assessing cardiorespiratory fitness and may be used to examine performance fatigability (decline in performance during a given activity) in persons with TBI.Purpose: To examine the effect of aerobic exercise training on oxygen uptake on-kinetics during treadmill walking in individuals with TBI.Methods: Seven ambulatory adults with chronic non-penetrating TBI performed short moderate-intensity (3-6 metabolic equivalents) walking bouts on a treadmill, prior to and following an aerobic exercise training program (clinicaltrials.gov: NCT01294332). The 12-week training program consisted of vigorous-intensity exercise on a treadmill for 30 min, 3 times a week. Breath-by-breath pulmonary gas exchange was measured throughout the bouts, and oxygen uptake on-kinetics described the time taken to achieve a steady-state response.Results: Faster oxygen uptake on-kinetics was observed after exercise training, for both the absolute and relative intensity as pre-training.Conclusions: Faster oxygen uptake on-kinetics following aerobic exercise training suggests an attenuated decline in physical performance during a standardized walking bout and improved performance fatigability in these individuals with TBI.Implications for rehabilitationSevere fatigue is a common complaint among persons with traumatic brain injury (TBI).Oxygen uptake on-kinetics may be used as an objective physiological measure of performance fatigability in persons with TBI.Faster oxygen uptake on-kinetics following aerobic exercise training suggests improved performance fatigability in these individuals with TBI.Aerobic exercise training appeared beneficial for reducing performance fatigability and may be considered as part of the rehabilitative strategy for those living with TBI.

The relationship between lower limb muscle strength and lower extremity function in HIV disease

Background

Human immunodeficiency virus (HIV) negatively impacts muscle strength and function. This study aimed to establish the relationship between lower limb muscle strength and lower extremity function in HIV disease.

Method

A cross-sectional study was undertaken with a sample of 113 HIV-positive participants. Lower limb muscle strength and self-reported function were established using dynamometry and the Lower Extremity Functional Scale (LEFS), respectively. Muscle strength and functional status were established in a subset of 30 HIV-negative participants to determine normative values.

Results

Muscle strength for participants with HIV ranged from an ankle dorsiflexion mean of 9.33 kg/m² to 15.79 kg/m² in hip extensors. In the HIV-negative group, ankle dorsiflexors recorded 11.17 kg/m², whereas hip extensors were the strongest, generating 17.68 kg/m². In the HIV-positive group, linear regression showed a positive relationship between lower limb muscle strength and lower extremity function (r = 0.71, p = 0.00). Fifty per cent of the changes in lower extremity function were attributable to lower limb muscle strength. A simple linear regression model showed that lower limb ankle plantar flexors contributed the most to lower extremity function in this cohort, contrary to the literature which states that hip and trunk muscles are the most active in lower limb functional activities.

Conclusion

Lower extremity strength impacts perceived function in individuals stabilised on antiretroviral therapy for HIV disease. These findings demonstrate that ankle plantar flexors produce more force over hip flexors. Careful attention should be paid to the implications for strength training in this population.

Physical fitness characteristics of active duty US Air Force members with HIV infection

Human immunodeficiency virus (HIV) infection is associated with reduced muscle mass and adverse metabolic effects. We evaluated the impact of HIV infection on longitudinal exercise performance in US Air Force (USAF) members with HIV infection.USAF members perform standardized fitness assessments every 6 to 12 months with a composite score comprised of abdominal circumference, push-ups, sit-ups, and 1.5-mile run. Fitness tests between 2004 and 2014 for male USAF members with HIV infection (n = 172) were compared with male HIV-negative controls (∼10 per case; n = 1636) matched by age and rank category at service entry.Fitness tests for cases (n = 1821) were divided into 2 groups, before (pre-HIV) and after (post-HIV) diagnosis, and compared with control fitness assessments (n = 30,443) by paired t tests. Random-effects regression analyses were also performed to compare fitness components.Mean composite scores for cases were higher post-HIV (87.06 ± 9.10) compared with pre-HIV (84.92 ± 8.36; P = 0.004) and did not differ from respective controls. Compared with pre-HIV, mean push-up (51.50 ± 9.67 vs 50.35 ± 11.18; P = 0.018) and sit-up (51.66 ± 7.81 vs 50.57 ± 9.19; P < 0.001) counts improved post-HIV, whereas run times were similar (11:53 ± 1:42 vs 11:51 ± 2:05; P = 0.056). Regression analyses demonstrated that cases had significantly lower predicted abdominal circumference and push-up counts over time compared with controls, regardless of pre-HIV or post-HIV status (P < 0.05 for all).Although functional limitations may occur in the setting of HIV infection, vigorous exercise performance can be both preserved and improved in HIV-infected individuals at a level comparable with HIV-uninfected persons.

Effects of Combined Aerobic and Resistance Exercise on Exercise Capacity, Muscle Strength and Quality of Life in HIV-Infected Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Many HIV-infected patients demonstrate disability and lower aerobic capacity. The inclusion of resistance training combined with aerobic exercise in a single program is known as combined aerobic and resistance exercise (CARE) and seems to be an effective strategy to improve muscle weakness, as well as aerobic capacity in HIV-infected patients. We performed a meta-analysis to investigate the effects of CARE in HIV-infected patients.

METHODS

We searched MEDLINE, Cochrane Controlled Trials Register, EMBASE, CINAHL (from the earliest date available to august 2014) for controlled trials that evaluated the effects of CARE in HIV-infected patients. Weighted mean differences (WMD) and 95% confidence intervals (CIs) were calculated, and heterogeneity was assessed using the I2 test.

RESULTS

Seven studies met the study criteria. CARE resulted in improvement in Peak VO2 WMD (4.48 mL·kg-1·min-1 95% CI: 2.95 to 6.0), muscle strength of the knee extensors WMD (25.06 Kg 95% CI: 10.46 to 39.66) and elbow flexors WMD (4.44 Kg 95% CI: 1.22 to 7.67) compared with no exercise group. The meta-analyses also showed significant improvement in Health status, Energy/Vitality and physical function domains of quality of life for participants in the CARE group compared with no exercise group. A nonsignificant improvement in social function domain of quality of life was found for participants in the CARE group compared with no exercise group.

CONCLUSIONS

Combined aerobic and resistance exercise may improve peak VO2, muscle strength and health status, energy and physical function domains of quality of life and should be considered as a component of care of HIV-infected individuals.

Association of the veterans aging cohort study index with exercise capacity in HIV-infected adults

Physical disability is a major priority in aging, affecting morbidity, mortality, and quality of life. Despite the large number of adults aging with HIV, our understanding of the physiologic and clinical risk factors for disability is limited. Our goal is to determine whether the Veterans Aging Cohort Study (VACS) Index, based on routine clinical blood tests, could serve as a point of care screening tool to identify HIV-infected adults at high risk for physical disability. HIV-infected adults enrolled in the VACS participated in a cross-sectional exercise study with established measures of strength and endurance. The VACS Index was calculated using recent clinical laboratory values and age; a higher score reflects greater mortality risk. Statistical analyses included correlation and linear regression models adjusted for muscle mass. Fifty-five HIV-infected adults, predominantly African-American men, were included with age mean±SD of 52±7 years. Median (IQR) CD4 cell count was 356 cells/mm(3) (212-527). The VACS Index was inversely correlated with quadriceps strength (r=-0.45, p<0.01), grip strength (r=-0.28, p=0.04), and 6-min walk distance (r=-0.27, p=0.05). A 20-point increase in VACS Index score was associated with a 10% lower leg strength (p<0.01), which remained significant after adjustment for muscle cross-sectional area (p=0.02). The VACS Index explained 31% of the variance in specific leg strength. In this group of middle-aged adults with well-controlled HIV infection the VACS Index was significantly associated with upper and lower extremity strength. The VACS Index may be valuable for identification of patients at high risk for disability due to muscle weakness.

Sports behaviour among HIV-infected versus non-infected individuals in a Berlin cohort

Physical activity has been recommended based on beneficial effects described in HIV-infected patients. However, such guidelines do not take into account actual sport behaviours and general attitudes towards physical activity. To evaluate actual sport activity and attitudes towards sport in HIV-infected versus non-infected individuals we conducted an anonymous questionnaire investigating the prevalence, as well as possible changes, in sports engagement and the overall attitude to physical activity. A total of 283 patients of a general care facility specialized in the treatment of HIV/AIDS in Berlin, Germany, participated; 124 were HIV infected and 159 were non-infected, mostly men who have sex with men (MSM) (88%), with a median age of 35 years. The HIV-infected participants had a median CD4+ count of 554 cells/µL and 48.8% of them were using antiretroviral therapy (ART) at the time of survey. The proportion of patients actually performing physical activity was significantly lower (P = 0.028) within the HIV-infected group (61.3%) than within the non-infected group (74.2%). This difference remained significant after accounting for possible confounders such as age, gender, injecting drug use and sexual preferences. Previously reported sport activity prevalence was similar in both groups on leaving school. From our data we could not identify an association between the time of HIV diagnosis and changes in sports activity. In conclusion, fewer HIV-infected individuals report physical activity than non-infected individuals. Sociodemographic studies to evaluate potential differences in sports behaviour are required in order to inform exercise guidelines for HIV-infected patients.

Exploratory study on oxygen consumption on-kinetics during treadmill walking in women with systemic lupus erythematosus

OBJECTIVE

To determine whether oxygen consumption (V o(2)) on-kinetics differed between groups of women with systemic lupus erythematosus (SLE) and sedentary but otherwise healthy controls.

DESIGN

Exploratory case-control study.

SETTING

Medical school exercise physiology laboratory.

PARTICIPANTS

Convenience samples of women with SLE (n=12) and sedentary but otherwise healthy controls (n=10).

INTERVENTION

None.

MAIN OUTCOME MEASURES

V o(2) on-kinetics indices including time to steady state, rate constant, mean response time (MRT), transition constant, and oxygen deficit measured during bouts of treadmill walking at intensities of 3 and 5 metabolic equivalents (METs).

RESULTS

Time to steady state and oxygen deficit were increased and rate constant was decreased in the women with SLE compared with controls. At the 5-MET energy demand, the transition constant was lower and MRT was longer in the women with SLE than in controls. For a similar relative energy expenditure that was slightly lower than the anaerobic threshold, the transition constant was higher in controls than in women with SLE.

CONCLUSION

V o(2) on-kinetics was prolonged in women with SLE. The prolongation was concomitant with an increase in oxygen deficit and may underlie performance fatigability in women with SLE.

Exercise training reduces central adiposity and improves metabolic indices in HAART-treated HIV-positive subjects in Rwanda: a randomized controlled trial

As HAART becomes more accessible in sub-Saharan Africa, metabolic syndromes, body fat redistribution (BFR), and cardiovascular disease may become more prevalent. We conducted a 6-month, randomized controlled trial to test whether cardiorespiratory exercise training (CET), improves metabolic, body composition and cardiorespiratory fitness parameters in HAART-treated HIV(+) African subjects with BFR. Six months of CET reduced waist circumference (-7.13 +/- 4.4 cm, p < 0.0001), WHR (-0.10 +/- 0.1, p < 0.0001), sum skinfold thickness (-6.15 +/- 8.2 mm, p < 0.0001) and % body fat mass (-1.5 +/- 3.3, p < 0.0001) in HIV(+)BFR(+)EXS. Hip circumference was unchanged in non-exercise control groups. CET reduced fasting total cholesterol (-0.03 +/- 1.11 mM, p < 0.05), triglycerides (-0.22 +/-0.48 mM, p < 0.05) and glucose levels (-0.21 +/- 0.71 mM, p < 0.05) (p < 0.0001). HDL-, LDL-cholesterol and HOMA values were unchanged after CET. Interestingly, HIV(+) subjects randomized to non-exercising groups experienced increases in fasting plasma glucose levels, whereas HIV seronegative controls did not (p < 0.001). Predicted VO(2) peak increased more in the HIV(+)BFR(+)EXS than in all other groups (4.7 +/- 3.9 ml/kg/min, p < 0.0001). Exercise training positively modulated body composition and metabolic profiles, and improved cardiorespiratory fitness in HAART-treated HIV(+) Africans. These beneficial adaptations imply that exercise training is a safe, inexpensive, practical, and effective treatment for evolving metabolic and cardiovascular syndromes associated with HIV and HAART exposure in resource-limited sub-Saharan countries, where treatment is improving, morbidity and mortality rates are declining, but where minimal resources are available to manage HIVand HAART-associated cardiovascular and metabolic syndromes.

Central activation, muscle performance, and physical function in men infected with human immunodeficiency virus

Loss of muscle mass and limitations in activity have been reported in persons infected with human immunodeficiency virus (HIV), even those who are otherwise asymptomatic. The extent to which factors other than muscle atrophy impair muscle performance has not been addressed in depth. The purpose of this study was to determine the extent of neuromuscular activation of the knee extensors and ankle dorsiflexors of 27 men infected with HIV receiving antiretroviral therapy and its relationship to muscle performance. The central activation ratio (CAR) was determined using superimposed electrical stimulation during maximum voluntary contractions. In addition to force and power measurements, muscle cross-sectional area and composition was evaluated using computed tomography. Aerobic capacity was determined from treadmill exercise testing. Eleven of the subjects had an impaired ability to activate the knee extensors (CAR = 0.72 +/- 0.12) that was associated with weakness and decreased specific force. The reduced central activation was not associated with muscle area, body composition, aerobic capacity, CD4 count, or medication regimen. Those individuals with low central activation had higher HIV-1 viral loads and were more likely to have a history of AIDS-defining illness. These results suggest the possibility of a different mechanism contributing to muscle impairment in the current treatment era that is associated with impairment of central motor function rather than atrophy. Further investigation is warranted in a larger, more diverse population before more definitive claims are made.

Physical activity in a cohort of HIV-positive and HIV-negative injection drug users

Physical activity is beneficial for persons with HIV infection but little is known about the relationships between physical activity, HIV treatment and injection drug use (IDU). This study compared physical activity levels between HIV-negative and HIV-positive injection drug users (IDUs) and between HIV-positive participants not on any treatment and participants on highly active antiretroviral therapy (HAART). Anthropometric measurements were obtained and an interviewer-administered modified Paffenbarger physical activity questionnaire was administered to 324 participants in a sub-study of the AIDS Linked to Intravenous Experiences (ALIVE) cohort, an ongoing study of HIV-negative and HIV-positive IDUs. Generalized linear models were used to obtain univariate means and to adjust for confounding (age, gender, employment and recent IDU). Vigorous activity was lower among HAART participants than HIV-positive participants not on treatment (p=0.0025) and somewhat lower than HIV-negative participants (p=0.11). Injection drug use and viral load were not associated with vigorous activity. Energy expenditure in vigorous activity was also lower among HAART participants than both HIV-negative and HIV-positive participants not on treatment. Thus, HIV-positive participants on HAART spend less time on vigorous activity independent of recent IDU. More research is needed into the reasons and mechanism for the lack of vigorous activities, including behavioral, psychological and physiological reasons.

Effects of a supervised home-based aerobic and progressive resistance training regimen in women infected with human immunodeficiency virus: a randomized trial

BACKGROUND

Women infected with human immunodeficiency virus (HIV) increasingly demonstrate abnormalities in fat distribution and metabolism; however, the effects of a home-based exercise regimen in this group have not been investigated.

METHODS

We conducted a 16-week randomized intervention study of a supervised home-based progressive resistance training and aerobic exercise program in 40 HIV-infected women with increased waist-hip ratio and self-reported fat redistribution. Cross-sectional muscle area and muscle attenuation were measured by computed tomography. Cardiorespiratory fitness was determined by calculated maximum oxygen consumption (VO2max) and strength by 1-repetition maximum.

RESULTS

Cardiorespiratory fitness (VO2max) was markedly lower at baseline (median [95% confidence interval], 15.4 [8.3-25.2] mL x kg(-1) x min(-1)) than reported values for healthy female subjects (26-35 mL x kg(-1) x min(-1)). Subjects randomized to exercise had significant improvement in mean +/- SEM VO2max (1.5 +/- 0.8 vs -2.5 +/- 1.6 mL x kg(-1) x min(-1); P<.001) and endurance (1.0 +/- 0.3 vs -0.6 +/- 0.3 minute; P<.001). Strength increased at the knee extensors, pectoralis, knee flexors, shoulder abductors, ankle plantar flexors, and elbow flexors (all P<.001). Total muscle area (6 +/- 1 vs 2 +/- 1 cm2; P = .02) and attenuation (2 +/- 1 vs -1 +/- 1 Hounsfield unit; P = .03) increased in the exercise group. No significant difference was seen in lipid levels, blood pressure, or abdominal visceral fat between the groups, but subjects randomized to exercise reported improved energy and appearance.

CONCLUSIONS

A 16-week, supervised, home-based exercise regimen improved measures of physical fitness in HIV-infected women. The effects on strength were most significant, but improvements in cardiorespiratory fitness, endurance, and body composition were also seen.