Hemodynamic Effects Induced by Transcutaneous Electrical Nerve Stimulation in Apparently Healthy Individuals: A Systematic Review With Meta-Analysis.

OBJECTIVE: To determine the immediate effects of transcutaneous electrical nerve stimulation (TENS) on heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in apparently healthy adults (age ≥18y). DATA SOURCES: The Cochrane Library (online version 2014), PubMed (1962-2014), EMBASE (1980-2014), and LILACS (1980-2014) electronic databases were searched. STUDY SELECTION: Randomized controlled trials were included when TENS was administered noninvasively with surface electrodes during rest, and the effect of TENS was compared with that of control or placebo TENS. A sensitive search strategy for identifying randomized controlled trials was used by 2 independent reviewers. The initial search led to the identification of 432 studies, of which 5 articles met the eligibility criteria. DATA EXTRACTION: Two independent reviewers extracted data from the selected studies. Quality was evaluated using the PEDro scale. Mean differences or standardized mean differences in outcomes were calculated. DATA SYNTHESIS: Five eligible articles involved a total of 142 apparently healthy individuals. Four studies used high-frequency TENS and 3 used low-frequency TENS and evaluated the effect on SBP. Three studies using high-frequency TENS and 2 using low-frequency TENS evaluated the effect on DBP. Three studies using high-frequency TENS and 1 study using low-frequency TENS evaluated the effect on heart rate. A statistically significant reduction in SBP (-3.00mmHg; 95% confidence interval [CI], -5.02 to -0.98; P=.004) was found using low-frequency TENS. A statistically significant reduction in DBP (-1.04mmHg; 95% CI, -2.77 to -0.03; I(2)=61%; P=.04) and in heart rate (-2.55beats/min; 95% CI, -4.31 to -0.78; I(2)=86%; P=.005]) was found using both frequencies. The median value on the PEDro scale was 7 (range, 4-8). CONCLUSIONS: TENS seems to promote a discrete reduction in SBP, DBP, and heart rate in apparently healthy individuals.

Noninvasive ventilation improves the cardiovascular response and fatigability during resistance exercise in patients with heart failure.

PURPOSE: Noninvasive ventilation may improve cardiovascular function and exercise performance. We evaluated the physiologic impact of noninvasive ventilation during isokinetic knee extension resistance exercise in patients with heart failure. METHODS: This clinical trial included 10 male compensated patients with ischemic heart failure (age, 57 ± 9.1 years; ejection fraction, 28.5 ± 5.8%). Subjects underwent 2 bouts of exercise on an isokinetic dynamometer, separated by 72 hours of rest. The resistance exercise was concentric knee extension, at a speed of 60°/s. Five sets of 10 repetitions were performed during the 2 exercise bouts, and each set was separated by 2 minutes of rest. Subjects were administered either bilevel positive airway pressure ventilation (BV) or sham ventilation 20 minutes before and during the 2 exercise sessions in a randomized fashion. Heart rate, systolic blood pressure, and diastolic blood pressure were measured at rest, during exercise, and into recovery. Changes in peak torque (ΔPT), total work (ΔTW), and power (ΔPw) between the fifth and first sets were also measured. RESULTS: Compared with the sham intervention, BV significantly decreased heart rate, systolic blood pressure, and diastolic blood pressure at rest and during exercise (P < .01). There were no significant differences in these variables during recovery. Bi-level positive airway pressure ventilation also significantly reduced ΔPT, ΔTW, and ΔPw compared with the sham intervention (P < .01). CONCLUSIONS: Bi-level positive airway pressure ventilation significantly improved the cardiovascular response and fatigability during resistance exercise in patients with heart failure. These results suggest that use of BV during exercise training may be beneficial in this population with chronic disease.