[Effects of the combination of tangeretin and whey protein on testosterone and cortisol in sprinters at winter training season].

Objective: To evaluate the regulation efficacy of oral tangeretin on testosterone and cortisol in sprinters at winter training season. Methods: Twenty-four sprinters were paired and randomly divided into experimental group (EG) and control group (CG). During winter training season, EG were treated with 200 mg tangeretin by oral, and CG were treated with placebo for 4 weeks. Blood samples were collected on the first day of each week (T1, T2, T3, T4) and after the intervention (T5) to detect serum levels of testosterone, cortisol, superoxide dismutase (SOD), and adrenocorticotropic hormone (ACTH). The body composition was tested at T1 and T5. Results: After 4 weeks, ①the serum cortisol level of CG was increased, and the serum levels of testosterone and SOD were decreased significantly (P＜0.05). ②In EG, the serum levels of cortisoland ACTH were decreased significantly (P＜0.05, P＜ 0.01), while the serum testosterone level was remained stable, and the level of SOD was increased slightly. ③The muscle mass of EG and CG were increases, but that of EG was increased higher than that of CG. Conclusion: Tangeretin reduces the oxidative stress response that caused by high-intensity exercise during winter training, which maintain the serum testosterone level and inhibit cortisol excessive secretion and promote muscle synthesis.

[Effects of Tangeretin on cortisol stress response induced by high-intensity resistance exercise].

Objective: To investigate the effects of 4-week tangeretin supplementation on cortisol stress response induced by high-intensity resistance exercise. Methods: Twenty-four sprinters were paired and randomly divided into experimental group (EG) and control group (CG). EG orally took supplement with tangeretin (200 mg/day) and CG took placebo for 4 weeks. Before and after the 4-week intervention, all sprinters performed a set of high-intensity resistance exercise (shoulder press, squat, bench press and deadlift, 10 RM, 4 sets per movement) to stimulate their cortisol stress responses. Serum levels of cortisol, adreno-corticotropic hormone (ACTH), superoxide dismutase (SOD), white blood cell count (WBC) and blood glucose were obtained by collecting blood sample before the exercise (PRE), immediately after the exercise (P0), and at 10 (P10), 20 (P20), and 30 minutes (P30) after the exercise. Results: Compared with the same period before the intervention, after the 4-week tangeretin intervention, EXP showed significantly reduced serum cortisol level at PRE (P=0.017), P10 (P=0.010), P20 and P30 (P＜0.05 or P＜0.01), and significantly reduced WBC at PRE, ACTH at P10 (P=0.037) and WBC and ACTH at P30 (P＜0.05). Compared with CTROL, EXP showed significantly lower levels of the serum cortisol at PRE and P10 (P＜0.05), and significantly lower levels of the ACTH (P＜0.05) and WBC (P＜0.01) at P30, and significantly increased level of the SOD activity at P30 (P＜0.05). Conclusion: Tangeretin supplementation can significantly alleviate the cortisol stress response induced by high-intensity resistance exercise, inhibit the excessive secretion of cortisol, enhance antioxidant capacity, accelerate the elimination of inflammation in the body, and promote the recovery of body functions.

Effect of backpack load on the head, cervical spine and shoulder postures in children during gait termination.

Twelve boys with an average age of 9.9 years were instructed to carry backpacks that weighed 0%, 10% and 15% of their body weights (BWs) to complete planned and unplanned gait termination experiments. The craniohorizontal, craniovertebral and sagittal shoulder posture angles at the sagittal plane as well as the anterior head alignment and coronal shoulder posture angles at the coronal plane were analysed. Results revealed significantly smaller craniohorizontal and sagittal shoulder posture angles during planned gait termination and a significantly smaller sagittal shoulder posture angle during unplanned gait termination under loaded conditions compared with those at 0% BW backpacks. Furthermore, the coronal shoulder posture angles at 10% and 15% BW during planned and unplanned gait terminations were significantly larger than those at 0% BW. Therefore, subjects were more likely to have a forward head posture, rounded shoulder posture and increased lateral tilting of the shoulders during gait termination as backpack loads were increased. However, gait termination, whether planned or unplanned, did not elicit a remarkable effect on posture.