Author(s): YALDIZ KAYMAZ, B., CAZORLA-SARAVIA, P., GONZÁLEZ-ALONSO, J., Institution: BRUNEL UNIVERSITY OF LONDON, Country: UNITED KINGDOM, Abstract-ID: 2134

INTRODUCTION:
Exercise and thermal interventions are frequently recommended to enhance vascular function and overall health in both young and older adults (1,2). Despite the strong evidence supporting exercise and the growing interest in heat-based interventions, findings on their combined use remain inconsistent. Although recent research indicates that adding heating to small-muscle mass exercise can produce additive effects (3,4), it is unclear whether similar benefits occur with larger-muscle mass exercise, such as walking. Therefore, we investigated regional (leg, arm and head) and systemic haemodynamic, ventilatory, metabolic and thermal-sensation responses during passive two-leg heating alone and in combination with low-intensity treadmill walking, in healthy young adults, and compared these responses with control conditions.
METHODS:
Fifteen physically active young adults (8 males, 7 females; age 23 ± 5 years) completed two separate visits: a control condition and a heating condition. Each visit consisted of 1 h of supine rest, 30 min of low-intensity treadmill walking (4 km/h), and 1 h of supine recovery. During the heating condition, passive heating was applied throughout the resting and walking periods using a pair of custom-made heating trousers. During each experimental trial, temperature and tissue oxygen saturation profiles; leg, arm, head, and systemic haemodynamics; and respiratory, metabolic, and thermal sensation responses were repeatedly measured.
RESULTS:
During rest and walking, bilateral leg heating increased leg skin temperature and two-leg blood flow by +8.4–5.5 °C, and +0.8 L/min, respectively, compared to control (P < 0.05), meanwhile forearm and head skin temperature, blood flow, and tissue oxygen saturation remained unchanged under both conditions (P > 0.05). Leg heating increased core temperature during walking to 37.7 ± 0.2°C (+0.3 °C vs control), yet aerobic metabolism (VO2), pulmonary ventilation, and expiratory gases remained similar in both trials during rest, walking and recovery (P > 0.05). Thermal sensation during the control rest and walking was rated as ‘slightly cool’ to ‘neutral’ (-1 to 0), whereas during the heating was rated as ‘slightly warm’ to ‘warm’ (1 to 2).
CONCLUSION:
Bilateral leg heating enhances lower limb perfusion during rest and walking without affecting blood flow in the upper limbs or head, respiratory function, or whole-body metabolism. Therefore, the combination of bilateral leg heating with low-intensity walking represents a practical, effective, and safe intervention to enhance circulatory function and vascular health in individuals with reduced physiological capacity, without inducing systemic physiological strain or thermal discomfort.