Acu-TENS lowers blood lactate levels and enhances heart rate recovery after exercise

Objective||The primary aim of this study is to investigate the effect of application of transcutaneous electrical nerve stimulation over acupuncture points (Acu-TENS) on post-exercise blood lactate level. The secondary aim is to explore the effect of Acu-TENS on heart rate recovery and its association with autonomic nervous system.||Methods||Twenty healthy subjects (mean age 26.9 ± 1.3) acting as their own controls, were randomized to receive either Acu-TENS or Placebo-TENS as the first of two intervention protocols, implemented one week apart. During Acu-TENS, subjects received 45 min TENS bilaterally over the acupoints Neiguan (PC6). Subjects receiving Placebo-TENS had identical electrode placement but with no electrical output from the TENS unit despite an active output light. Interventions were followed by a 10-min ergometer exercise at 70% age-predicted maximal heart rate. Oxygen consumption and heart rate (HR) were recorded continuously throughout exercise. Blood lactate and blood pressure were taken at 4 time points: prior to, immediately after, at 15-min after exercise, and when HR had returned to baseline values.||Results||The post-exercise blood lactate level in the Acu-TENS group was lower than that of the placebo group by 1.12 ± 0.39 mmol/L (p = 0.01). The Acu-TENS group also had a faster return of HR to pre-exercise level compared to placebo (9.98 ± 4.54 min, p = 0.047). Heart rate variability analysis inferred reduced sympathetic modulation during exercise after Acu-TENS. There was no between-group difference in post-exercise oxygen consumption.||Conclusion||Acu-TENS lowered post-exercise blood lactate level and enhanced heart rate recovery after moderate exercise. The role of Acu-TENS in exercise performance and energy metabolism warrants further investigation. (ClinicalTrails.gov Identifier: NCT01102634)