摘要
The purpose of this study was to verify the association between angiotensin-converting enzyme (ACE) genotypes DD, DI, and II and caffeine (CAF) ingestion on endurance performance, heart rate, ratio of perceived exertion (RPE), and habitual caffeine intake (HCI) of adolescent athletes. Seventy-four male adolescent athletes (age: DD=16±1.7; DI=16±2.0; II=15±1.7 years) ingested CAF (6 mg/kg) or placebo (PLA) one hour before performing the Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) test. No difference was found among groups for HCI. However, CAF increased the maximal distance covered and VO2max in DI and II genotype carriers compared to PLA (DD: Δ=31 m and 0.3 mL·kg-1·min-1; DI: Δ=286 m and 1.1 mL·kg-1·min-1; II: Δ=160 m and 1.4 mL·kg-1·min-1). Heart rate of DI and II genotype carriers increased with CAF compared to PLA, while RPE was higher in the II and lower in the DD genotypes. The correlations between HCI and maximal distance covered or VO2max were significant in the II genotype carriers with CAF. CAF increased endurance capacity, heart rate, and RPE in adolescent athletes with allele I, while endurance performance and aerobic power had a positive correlation to HCI in the II genotype group. These findings suggested that DD genotype were less responsive to CAF and that genetic variations should be taken into account when using CAF supplementation to enhance exercise performance.
摘要
The aim was to investigate the long-term effects of metformin ingestion on high-intensity interval training on performance, glycogen concentration (GC), GLUT-4 content, and metabolomics outcomes in rats. Fifty male Wistar rats were randomly divided into baseline, metformin (500 mg daily), and control groups. Training consisted of 4 sets of 10 jumps with 30 s of passive recovery per day, 5 days/week for 8 weeks. The intensity equivalent was 50% of body mass (BM) in the first four weeks and 70% of BM in the last four weeks. The animals were submitted to a weekly jump test until exhaustion at 50% of BM. Serum and tissues were collected at baseline and after 4 and 8 weeks for biochemical and metabolomics analysis. The number of jumps increased in the Control group without a significant difference between groups at 4 and 8 weeks. GLUT4 was lower in the gastrocnemius muscle in the Metformin at the fourth week compared to Control (P=0.03) and compared to Metformin (P=0.02) and Control (P=0.01) at eight weeks. Hepatic and soleus GC were not altered by metformin. Gastrocnemius GC was lower after 8 weeks in the Metformin group compared to Control (P=0.01). Significantly lower levels of pyruvate and phenylalanine and higher levels of ethanol, formate, betaine, very low-density lipoprotein, low-density lipoprotein, and creatine were found in the Metformin compared to the Control. Although chronic administration of metformin decreased food intake and negatively influenced the synthesis of muscle glycogen, it did not significantly change physical performance compared to the Control.