Effects of 4-Week Inspiratory Muscle Training on Sport Performance in College 800-Meter Track Runners.

Background and objectives: Respiratory muscle fatigue is one of the important factors limiting sports performance due to the metaboreflex. This reflex will cause a decrease in blood flow to the extremities and accelerate exercising limb fatigue. Previous studies found that inspiratory muscle training (IMT) can effectively enhance the respiratory muscle endurance and reduce fatigue during long-duration exercise or aerobic exercise, thereby enhancing athletic performance. However, the mechanism between inspiratory muscle strength, change of limb blood flow and sports performance still requires investigation, especially in short-duration exercise, anaerobic or both aerobic and anaerobic exercise. The purpose of this study was to investigate the effects of 4-week inspiratory muscle training on respiratory muscle strength, limb blood flow change rate and sports performance in recreational 800-m college runners. Materials and Methods: Twenty healthy 800-m college runners randomized into the IMT group (11 subjects) and control group (9 subjects). IMT consisted of 30 inspiratory efforts twice daily, 5 days a week, with intensity at 50%, 60%, 70% and 80% of maximum inspiratory pressure (MIP) for 4 weeks, while a control group kept 50% of MIP for 4 weeks. An 800-m trial test, limb blood flow change rate by using Impedance Plethysmography, and MIP were as the outcome measured variables and be evaluated. All measured variables were assessed before and after 4-week IMT training. Two-way ANOVA was conducted for statistical analysis. Results: The results showed significantly interaction between groups and pre-posttest. IMT group significantly decreased limb blood flow change rate from 19.91 ± 11.65% to 9.63 ± 7.62% after received the IMT training program (p < 0.05). The MIP significantly improved from 112.95 ± 27.13 cmH2O to 131.09 ± 28.20 cm H2O in IMT group, and the 800-m trial test also shorted the running time from 162.97 ± 24.96 s to 156.75 ± 20.73 s. But the control group no significantly changed in MIP and 800-m trial test. Conclusions: Our results indicated that the 4-week IMT training (twice a day, 5 days a week) significantly improves participants' inspiratory muscle strength, 800-m running performance and decreases the limb blood flow change rate.

Ubiquinone Supplementation with 300 mg on Glycemic Control and Antioxidant Status in Athletes: A Randomized, Double-Blinded, Placebo-Controlled Trial.

The aim of this study is to investigate the glycemic profile, oxidative stress, and antioxidant capacity in athletes after 12 weeks of ubiquinone supplementation. It was a double-blinded, randomized, parallel, placebo-controlled study. Thirty-one well-trained college athletes were randomly assigned to ubiquinone (300 mg/d, n = 17) or placebo group (n = 14). The glycemic profile [fasting glucose, glycated hemoglobin (HbA1c), homeostatic model assessment-insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI)], plasma and erythrocyte malondialdehyde (MDA), total antioxidant capacity (TAC), and ubiquinone status were measured. After supplementation, the plasma ubiquinone concentration was significantly increased (p < 0.05) and the level of erythrocyte MDA was significantly lower in the ubiquinone group than in the placebo group (p < 0.01). There was a significant correlation between white blood cell (WBC) ubiquinone and glycemic parameters [HbA1c, r = -0.46, p < 0.05; HOMA-IR, r = -0.67, p < 0.01; QUICKI, r = 0.67, p < 0.01]. In addition, athletes with higher WBC ubiquinone level (≥0.5 nmol/g) showed higher erythrocyte TAC and QUICKI and lower HOMA-IR. In conclusion, we demonstrated that athletes may show a better antioxidant capacity with higher ubiquinone status after 12 weeks of supplementation, which may further improve glycemic control.