ABSTRACT
BACKGROUND: Maximal oxygen uptake (VO2 max) is the most direct, effective and objective index for determining cardiorespiratory endurance and exercise capacity, but there are few studies on the varying data of VO2max in rats for a long time. In addition, the effect of high-intensity interval training on the cardiorespiratory endurance in rats during age increasing has not yet been reported. OBJECTIVE: To investigate the improvement of 16-week high-intensity interval training on the cardiorespiratory endurance in rats, and to continuously measure the VO2 max for 16 weeks in 29-week-old rats, so as to provide data reference for the precise control of training intensity. METHODS: Twenty-eight male Wistar rats aged 29 weeks old were randomly assigned into a quiet control group (normal feeding, no training) and a high-intensity interval training group. The latter group underwent the interval exercise of high-intensity (90% VO2 max) and low-intensity (50% VO2 max), 5 times per week, for 16 weeks. The VO2 max and corresponding maximal running velocity were tested and compared every 2 weeks. The study was approved by the Ethics Committee of Sports Science and Physical Health Education Department, Beijing Sport University, with the approval No. 2015025. RESULTS AND CONCLUSION: (1) With the increasing age from 29 to 45 weeks, the VO2max fluctuated down-up-down. After 16 weeks of exercise, the VO2max was decreased by 31.6% in the high-intensity interval training group and 47.9% in the quiet control group. The VO2 max in the high-intensity interval training group was significantly higher than that in the quiet control group (P < 0.01). (2) The decrease of VO2 max in the high-intensity interval training group was significantly lower than that in the quiet control group at 6,8, and 16 weeks (P < 0.05 or P < 0.01). (3) The increase of maximal running velocity in the high-intensity interval training group was significantly higher than that in the quiet control group at 4 and 8 weeks (P < 0.05 or P < 0.01). (4) The maximal running velocity was positively correlated with VO2 max in rats. (5) These results suggest that age increasing is an irreversible factor, and high-intensity interval training can alleviate the decrease of cardiorespiratory endurance. Six-week high-intensity interval training can significantly improve the decrease of cardiorespiratory endurance in rats due to age increasing. Eight-week high-intensity interval training can significantly delay the decrease of cardiorespiratory endurance in rats due to age increasing. Four-week high-intensity interval training can promote the value of maximal running velocity and improve sports ability.