Effects of Lower Limb Heat Therapy, Exercise Training, or a Combined Intervention on Vascular Function: A Randomized Controlled Trial.

PURPOSE: The purpose of this study is to compare the effects of 8 wk of no intervention (CON), lower limb heat therapy (HEAT), moderate-intensity exercise training (EX), or combined training and therapy (HEATEX) in young, healthy recreationally active adults.

METHODS

Sixty participants (23 ± 3 yr, 30 females) were randomly allocated into CON ( n = 15), HEAT ( n = 15), EX ( n = 14), or HEATEX ( n = 16). The primary outcome was vascular function, assessed through brachial artery flow-mediated dilation tests. Secondary measures included arterial stiffness (pulse wave velocity), cardiorespiratory fitness (V̇O 2peak ), body composition, and quadriceps muscle strength.

RESULTS

There were no differences in brachial artery flow-mediated dilation between the groups before and after the interventions (all P > 0.05). Both interventions with a heating component were associated with within-group reductions in carotid-femoral pulse wave, and increase in absolute and relative V̇O 2peak after 8 wk (HEAT: ∆-0.27 [-0.53, -0.02] m s -1 , ∆0.18 [0.06, 0.29] L·min -1 , ∆2.18 [0.60, 3.76] mL·kg -1 ·min -1 , respectively; HEATEX: ∆-0.33 [-0.58, -0.09], ∆0.21 [0.11, 0.32] L·min -1 , ∆2.59 [1.06, 4.12] mL·kg -1 ·min -1 , respectively), but no between-group differences were observed ( P = 0.25, P = 0.21, and P = 0.55, respectively). There was also a within-group decrease in body fat percentage with EX (∆-1.37 [-2.45, -0.29] %), but no changes in leg strength in any of the groups ( P = 0.79).

CONCLUSIONS

This randomized controlled trial is the first to examine the efficacy of lower limb heating against traditionally prescribed exercise training. In our young cohort, 8 wk of training and/or therapy was insufficient to improve vascular function. More intense protocols and longer interventions involving lower limb heating may be required to elicit improvements in health outcomes.