The aim of this study was to investigate the effects of acute high-intensity interval training (HIIT) on immune function and oxidative stress in male canoe/kayak athletes who were well trained. A total of 22 participants were voluntarily recruited with an age range of 15.9 ± 2.3 years, height of 172.2 ± 5.5 cm, body mass of 63.30 ± 6.95 kg, and body fat of 13.77 ± 3.76%. The modified Wingate kayaking test on a kayak ergometer was performed by all participants. Blood samples were collected at three different time points: before the test (Pre-T), immediately after (Post-T), and 3 h post-test (Post-3 h). Saliva samples were collected at two different time points: before the test (Pre-T) and 3 h after the test (Post-3 h). Results indicated that acute canoe/kayak ergometry HIIT had significant effects on the percentages and counts of leukocytes, neutrophils, lymphocytes, and lymphocyte subsets. Additionally, it resulted in increased total LPS-stimulated neutrophil elastase release and alterations in plasma concentrations of superoxide dismutase, catalase, and TBARS. These findings suggest that conventional kayak HIIT regimens can have short-term effects on immune function and induce oxidative stress in athletes.

Background: It is known that lower-limb muscle strength is easily maintained in elderly people who practice Tai Chi, although it is necessary to maintain lower-limb muscle strength even as age increases in order to prevent falls. However, the effect of long-term Tai Chi practice and age on lower-limb ability is unclear in middle-aged and elderly people. This research was designed to compare lower-extremity parameters during a countermovement jump between middle-aged and elderly individuals who frequently practice Tai Chi Chuan and individuals in the general population who constituted the healthy group. Methods: There were four groups, and each group included 12 participants. Ten Vicon motion system infrared cameras and two Kistler force plates were used. The data were standardized and analysed using independent-measure two-way ANOVA. Results: The statistical results showed that there was no interaction between the age factor and exercise type factor. The statistics of age factor also showed that age may decrease the jump height (36.36%), peak knee power (24.74%) and peak ankle power (21%) during the take-off phase. In the exercise type factor, long-term Tai Chi training significantly increased the jump height (60%), peak knee moment (19.80%), peak ankle moment (8.06%), peak hip power (29.80%), peak knee power (31.23%) and peak ankle power (16.88%) during the take-off phase. Conclusion: This study shows that long-term Tai Chi training can slow ageing-related functional decline. According to the results of this study, middle-aged and elderly people are encouraged to regularly perform Tai Chi exercises to increase the strength of various muscle groups in the lower limbs and slow the lower-limb muscle changes caused by ageing.

This study investigated the effects of caffeine supplementation, carbohydrate mouth rinsing, and combined caffeine supplementation with carbohydrate mouth rinsing on the pulling performance and ratings of perceived exertion in indoor tug-of-war athletes. Eighteen tug-of-war athletes were recruited as participants. They underwent four supplementation protocols in a double-blind, single-factor, repeated-measures design: caffeine supplementation (CAF), carbohydrate solution mouth rinsing (CHO), combined caffeine supplementation with carbohydrate mouth rinsing (CAF-CHO), and a placebo (PLA). Each participant performed a maximal pulling test at 80% of their maximum pulling force, and the duration was recorded. Ratings of perceived exertion were also assessed. Data were analyzed using SPSS version 25.0 for Windows, and effect sizes (ES) were calculated. The main findings were as follows: (1) The CAF-CHO group showed a significantly longer pulling duration than the PLA and CHO groups (165.0 ± 69.2 s vs. 137.4 ± 48.9 s vs. 135.6 ± 66.6 s). (2) The CAF group also demonstrated a significantly longer pulling duration than the CHO group (162.0 ± 14.1 s vs. 135.6 ± 66.6 s). (3) Both the CAF-CHO and CAF groups exhibited large effect sizes (ω² > 0.14) compared to the PLA and CHO groups. Both caffeine supplementation combined with carbohydrate mouth rinsing and caffeine supplementation alone can significantly enhance the duration of 80% maximal pulling performance in indoor tug-of-war athletes, with the primary effect attributed to caffeine. These results provide practical strategies for coaches and athletes to suppress fatigue and improve pulling performance during competitions or training sessions for indoor tug-of-war.