Peripheral neuropathy (PN) is a neurological condition affecting the sensory, motor or autonomic peripheral nerves. The classification of PN is generally based on the cause or pathological features of the nerve fibres affected. It can be subdivided based on primary myelin or axonal damage into demyelinating or axonal PN.¹ The global estimate of HIV-associated neuropathy varies widely from 1.73% to 69.4% in different HIV-infected populations.² Sadly, PN was not only shown to be associated with HIV infection itself but in many cases also triggered by treatment with antiretroviral agents.³ Growing evidence of unwanted adverse effects of the early antiretrovirals (ARVs) led to the use of safer, later generation ART in many countries. Peripheral neuropathy nontheless still remains important as the most common neurological disorder of people living with HIV (PLHIV).⁴

A number of studies from resource-constrained settings including sub-Saharan Africa report that the risk of HIV-associated neuropathy amongst patients on ART to be high (between 30% and 64%).^5,6 Indeed, HIV-associated distal symmetrical polyneuropathy (DSPN) is reportedly the most common neurological complication of HIV infection.⁷ Individuals living with DSPN experience pain, numbness, fatigue and muscle weakness.^8,9 These symptoms may become debilitating with locomotor instability resulting in an altered gait, an increased rate and incidence of falls, and decreased quality of life (QOL).¹⁰ The falls are attributed to the balance and gait abnormalities.¹¹

Gait requires balance, power and coordination of larger groups of muscles of the lower extremities to permit the body to be propelled forward in a rhythmic motion. This function is diminished or lost in persons with neuropathy.¹²

Walking is a complex task that requires the coordinated function of the musculoskeletal, neuromuscular and cardiopulmonary systems. As DSPN progresses, symptoms such as ‘numbness’, pins and needles and ‘pain’ in the soles of the feet worsen the disturbed gait.¹³ Functional limitations, psychological distress and the loss of independence further compound the disability of those with HIV-associated DSNP.^14,15 These negative effects and the risk of injury impact the survival of affected individuals.^12,13

Exercise is generally regarded as safe for HIV-infected persons because it does not compromise immune function, boosts functional capacity, strength, physical fitness, mood, well-being, and may ameliorate muscle wasting and lipodystrophy.^16,17 Previous studies have investigated the effect of aerobic and resistance exercise individually or in combination on immune function, psychological factors, cardiorespiratory fitness, strength, body composition, QOL^17,18 and the ART-induced metabolic complications of PLHIV.¹⁹ The findings from these studies reveal that moderate- to high-intensity aerobic exercise is safe and elicits favourable and beneficial changes in all the variables examined.

Physical therapy interventions have been shown to help address balance impairment, gait disturbance and to have a positive effect on the QOL of persons with complex chronic illnesses.²⁰ In clinical practice, the physical therapists will use therapeutic resistance exercises that cause muscular contraction, microscopic damage/tearing of muscle, and repair that permits the restoration/increase of muscle power, tone, mass and endurance.²¹ A marked improvement in postural sway, joint flexibility, pain reduction, balance-stance, gait speed and QOL has been observed following ‘exergaming exercise’ and strength training by PLHIV who have postural and walking impairment.^17,22,23 A recent study further suggests that regular strength exercise may reduce HIV-neuropathic pain.²⁴

Studies of the role of exercise in the rehabilitation of those on ART and living with neuropathy are scarce.²⁴ To the best of the authors’ knowledge, there is no data on the impact of progressive resistance exercise (PRE) in the management of balance impairment and gait disturbance in HIV-positive individuals who develop DSPN. This study investigated the effect of PRE on balance impairment and the walking ability of HIV-positive individuals on ART and living with neuropathy.

The age range of the participants was 20–55 years. The mean (± standard deviation [± s.d.]) age of the experimental and CG were 35.98 (± 8.53) and 36.13 (± 8.10) years, respectively. The socio-demographic and basic health status characteristics of the participants were similar in all baseline measures between the groups (Table 1a and 1b). Seven (6.9%) of the 51 participants randomised to the PRE group dropped out, whilst four (3.9%) of the 51 randomised to the CG dropped out (Figure 1). Exercise subjects who did not drop out had excellent adherence attending 95% of scheduled exercise sessions.

Significant differences were observed for balance measures across the PRE group (p < 0.05; Table 2). Post-hoc analysis of Wilcoxon signed-rank test showed significant improvement from the baseline to 6 weeks of intervention (effect size r = 0.88, p = 0.001), from baseline to 12 weeks post-intervention (effect size 0.88, p = 0.001) and from 6 weeks to 12 weeks post-intervention (effect size r = 0.86, p = 0.001). In contrast, the CG experienced no significant improvement (p > 0.05).

Also, significant improvements for gait ability measures were observed across the PRE group (Table 2). Post-hoc analysis of Wilcoxon signed-rank test indicated significant improvement from baseline to 6 weeks (effect size r = 0.56, p = 0.001), from baseline to 12 weeks (effect size = 0.87, p = 0.001) and from 6 weeks to 12 weeks (effect size r = 0.79, p = 0.001). No positive changes in gait measures were observed over time in the CG (p < 0.05).

At 6 and 12 weeks of the intervention, statistically significant differences were observed between the experimental and the CG in balance measures with effect size r = 0.71, p = 0.001 and effect size r = 0.85, p = 0.001 respectively; and for gait measures with effect size r = 0.29, p = 0.006 and effect size r = 0.63, p = 0.001 (Table 3).

This study was conducted to evaluate the effect of strength training on balance impairment and gait disturbance in individuals affected with HIV-related neuropathy. The exercise intervention improved balance impairment and gait disturbance in people living with HIV-related DSPN on ART who exercised for three months. The exercise group demonstrated significant improvement from six weeks for both balance impairment and walking ability.

The findings of this study prove the beneficial effect of therapeutic exercise on neuromuscular pathology causing impairment and disability, and affecting QOL. There is limited existing information on the impact of exercise on balance impairment and gait disturbance amongst HIV-positive individuals who develop neuropathy. With regard to gait disturbance, the result of the current study corroborates the work of Allet et al.³⁰ who used 12 weeks of exercise to improve the gait performance of persons with diabetes. Significant favourable changes were observed in the gait performance of participants following a supervised strength exercise programme. In contrast, Kruse et al.³¹ found no positive changes in balance or strength in patients with diabetic neuropathy following supervised PRE for 60 min, twice a week for 12 weeks. They concluded that it could be because the treatment administered was not intense enough to produce a positive effect on balance and muscular strength. However, Graham et al.³² observed significant improvement in balance impairment in patients with non-HIV associated neuropathy after 12 weeks of unsupervised, community-based strengthening exercise, agreeing with the positive change noted in balance and walking ability following PRE in the current study. Richardson, Sandman and Velas³³ subjected patients with diabetic PN to PRE for three weeks every day for 35 min – 50 min per session using 60% – 70% of 1RM. Significant improvement was observed in clinical measures of postural performance (p < 0.05), which corroborates the finding of this study.

It has been stated that the strengthening of groups of muscles around the knee joint is related to positive changes in stride length and cadence during walking and can influence balance performance, in general. It is an intervention that can also improve walking ability.³⁴ Judge, Underwood and Gennosa³⁵ found that in older individuals with PN (mean age 82.1 years), 12 weeks of resistance exercises three times per week produced a significant modulating effect on strength, balance parameters and gait velocity when compared with a CG that performed only flexibility exercises (p < 0.05), tallying with results from the current study. These results accord with the postulated literature that states that resistance exercises can attenuate motor deficits caused by PN, thus improving inter- and intra-muscular coordination as well as neural control, and leading to improvement in balance impairment and gait disturbance.³⁶

This research study provided insights into the use of moderate-intensity strength exercises and the use of progressive resistance. The clinical implication is that PRE may be of use to physiotherapists when managing individuals with HIV-related DSPN for whom exercises are not contraindicated. This study supports the safety of moderate-intensity PRE and the improvement of impaired balance and walking disturbance in PLHIV-related DSPN. The use of PRE could minimise residual disabilities from HIV-related DSPN. This research study may serve as a starting point for further studies of larger sample size and longer duration.