title: Walk-run transition in young and older adults: with special reference to the cardio-respiratory responses.
abstract: Cardio-respiratory responses of young and older subjects performing walking and running protocols at the walk-run transition speed (WRT) were compared. A total of 26 volunteers assigned to younger (YG, 24 +/- 3 years) and older (OG, 64 +/- 6 years) groups underwent a protocol to determine the WRT used in 6-min walking and running protocols. Oxygen uptake (VO(2)), ventilation (V (E)), expired carbon dioxide (VCO(2)), heart rate (HR) and perceived exertion (RPE) were assessed. Oxygen pulse (O(2) pulse) and respiratory exchange ratio (RER) were calculated. The WRT was not different between groups (OG: 6.84 +/- 0.69 km h(-1) vs. YG: 7.04 +/- 0.77 km h(-1), P = 0.62). No between-group differences were found within a given gait pattern for VO(2) (P = 0.061) and VCO(2) (P = 0.076). However, VO(2) (P = 0.0022) and VCO(2) (P = 0.0041) increased in OG when running, remaining stable in YG (VO(2): P = 0.622; VCO(2): P = 0.412). The VE was higher in OG compared to YG in walking (P = 0.030) and running (P = 0.004) protocols. No age-related (P = 0.180) or locomotion (P = 0.407) effects were found for RER. The HR increased in OG and between-group difference was detected while running (P = 0.003). No within- (P = 0.447) or between-group (P = 0.851) difference was found for O(2) pulse. The net VO(2) increased from walking to running in OG (P < 0.0001) but not in YG (P = 0.53), while RPE was lower in YG (P = 0.041) but stable in OG (P = 0.654). In conclusion, the WRT speed was similar across the age groups. However, the VO(2) and VCO(2) increase from walking to running was larger for OG than YG. The HR, VE and RPE were also higher when running in OG compared to YG. Therefore, the locomotion strategy had different impacts on the metabolic demand of older and younger subjects.
authors.affiliation: Laboratory of Physical Activity and Health Promotion (LABSAU), Physical Education and Sports Institute, Rio de Janeiro State University (UERJ), Rua São Francisco Xavier 524, Maracanã-RJ, Brazil. pfarinatti@gmail.com
authors.forename: P T V
authors.initials: PT
authors.lastname: Farinatti
authors.forename: W D
authors.initials: WD
authors.lastname: Monteiro
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism; D002320:Cardiovascular Physiological Phenomena; D004734:Energy Metabolism; D045853:Exhalation; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D018763:Muscle Fatigue; D010101:Oxygen Consumption; D010465:Perception; D005082:Physical Exertion; D012123:Pulmonary Ventilation; D012143:Respiratory Physiological Phenomena; D012420:Running; D013997:Time Factors; D016138:Walking; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide