Effects of neuromuscular electrical stimulation and the Leeper on ankle blood flow in young adults

Purpose: there is growing incidence of sedentary behaviour (SB) in the UK, especially amongst older adults and office workers. SB predisposes individuals to venous stasis and vascular complications in the lower extremity. Footplate neuromuscular stimulation (NMES) devices and exercise devices facilitating active ankle movements, are thought to improve lower limb circulation. Unfortunately, there is limited research investigating blood flow in distal vasculature, such as the posterior tibial artery (PTA), which is most susceptible to endothelial dysfunction. Investigating the efficacy of these non-weight bearing, portable interventions is crucial to facilitating active living during prolonged sitting. This study aimed to compare the effects of NMES devices and active ankle movements using the new Leeper prototype on changes in blood flow in the PTA in healthy young adults.<br/><br/>Methods: this cross-over observational study was conducted between October and November 2024 using data from thirty healthy young adults in laboratory conditions in the University of Southampton’s Health Sciences building. In sitting, participants received NMES for 8 minutes at the minimum intensity level required to induce a visible contraction of gastrocnemius. After a 10-minute washout period, participants placed their feet on the Leeper dorsiflexing and plantarflexing, at a rate of 60 beats per minute for 8 minutes, guided by a metronome. An online randomisation tool randomised intervention order. Peak Systolic Velocity (PSV) of blood flow in the PTA was recorded using Doppler Ultrasonography at 0 and 8 minutes. Data were analysed for normality using the Shapiro-Wilk test. The Wilcoxon Signed Rank test was used to compare pre- and post-treatment data. A significance value of p&lt;0.05 was used.<br/><br/>Results: 16 male and 14 female participants were recruited (mean age 20.8 ± 1.9 years). There was a significant increase in PSV post-NMES use (12.3 m/s, [p=0.016, 95% CI=25.7]). The increase in PSV post-Leeper use approached but did not reach statistical significance (12.0 m/s [p=0.056, 95% CI=30.7]).<br/>There was no significant difference in the change in values between interventions (p=0.513). However, a higher number of participants exhibited a greater increase in PSV after NMES (n=14) compared to after the Leeper (n=11), and 5 participants were no different.<br/><br/>Conclusion(s): this study revealed no significant difference in change in PSV between interventions in the PSV in a young healthy population. NMES significantly increased PSV, while the Leeper showed a promising, albeit statistically non-significant, increase in PSV. These results indicate that NMES may prevent venous stasis, while the Leeper may require longer intervention durations or prolonged use to achieve similar benefits.<br/><br/>Impact: given the prevalence of SB, identifying interventions to enhance lower limb circulation is crucial. Our normative data adds to the limited research exploring NMES and the Leeper. This is one of few studies to consider blood flow changes in distal vasculature. This data could be compared with future studies investigating sedentary or older adult populations diagnosed with cardiovascular diseases. Clinically, these interventions could be implemented without the need for supervision as portable interventions in care homes and offices to promote activity and reduce venous stasis in non-ambulant populations.<br/>