Concurrent Ingestion of Alkaline Water and L-Glutamine Enhanced Salivary α-Amylase Activity and Testosterone Concentration in Boxing Athletes.

Athletes often take sport supplements to reduce fatigue and immune disturbances during or after training. This study evaluated the acute effects of concurrent ingestion of alkaline water and L-glutamine on the salivary immunity and hormone responses of boxers after training. Twelve male boxing athletes were recruited in this study. During regular training, the participants were randomly divided into three groups and asked to consume 400 mL of alkaline water (Group A), 0.15 g/kg body weight of L-glutamine with 400 mL of water (Group G), and 0.15 g/kg of L-glutamine with 400 mL of alkaline water (Group A+G) at the same time each day for three consecutive weeks. Before and immediately after the training, saliva, heart rates, and the rate of perceived exertion were investigated. The activity of α-amylase and concentrations of lactoferrin, immunoglobulin A (IgA), testosterone, and cortisol in saliva were measured. The results showed that the ratio of α-amylase activity/total protein (TP) significantly increased after training in Group A+G but not in Group A or G, whereas the ratios of lactoferrin/TP and IgA/TP were unaffected in all three groups. The concentrations of salivary testosterone after training increased significantly in Group A+G but not in Group A or G, whereas the salivary cortisol concentrations were unaltered in all groups. In conclusion, concurrent ingestion of 400 mL of alkaline water and 0.15 g/kg of L-glutamine before training enhanced the salivary α-amylase activity and testosterone concentration of boxers, which would be beneficial for post-exercise recovery.

Supplementation of L-glutamine enhanced mucosal immunity and improved hormonal status of combat-sport athletes.

BACKGROUND: Maintaining proper immune function and hormone status is important for athletes to avoid upper respiratory tract infection (URTI) and insufficient recovery, which is detrimental to sport performance and health. The aim of this study was to evaluate whether three-week supplementation of L-glutamine could benefit the mucosal immunity and hormonal status of combat-sport athletes as well as their rates of upper respiratory tract infection (URTI) and subjective feelings of well-being after intensive training. METHODS: Twenty-one combat-sport athletes from the National Taiwan University of Sport were recruited in this study. After intensive training, two groups of the participants were asked to consume powder form of 0.3 g/kg body weight of L-glutamine (GLU group) or maltodextrin (PLA group) with drinking water in a randomized design at the same time every day during 3 weeks. Saliva samples were collected to measure immunoglobulin A (IgA), nitric oxide (NO), testosterone (T) and cortisol (C) before and after three-week supplementation; moreover, Hooper's index questionnaires were completed for wellness assessment. The incidence and duration of URTI were recorded by using a health checklist throughout the entire study period. RESULTS: Supplementation of L-glutamine significantly enhanced the concentrations of IgA and NO in saliva; additionally, the incidence of URTI was significantly reduced. Regarding hormones, T concentration was significantly decreased in the PLA group, whereas C concentration was significantly increased, resulting in a significant decrease of T/C ratio. In contrast, the GLU group showed a significant increase of T/C ratio, while the mood scores of the Hooper's index questionnaire were higher in the PLA group. CONCLUSIONS: Three-week supplementation of L-glutamine after intensive training enhanced the mucosal immunity, improved hormonal status and reduced the rate of URTI of combat-sport athletes while feelings of well-being were also enhanced. Therefore, L-glutamine would be beneficial for the sports performance and recovery of athletes.

Beta-hydroxy-beta-methylbutyrate supplementation preserves fat-free mass in collegiate boxers during acute body mass loss.

Acute body mass loss before competitions in combat sports usually leads to loss in fat-free mass. Beta-hydroxy-beta-methylbutyrate (HMB) has been shown to increase skeletal muscle mass and muscle strength in various muscle wasting conditions. This study investigated the effect of HMB supplementation on body composition and sport-specific performance in well-trained boxers consuming a hypocaloric diet. Twelve male college boxers were divided into the HMB and placebo (PLA) groups using a body weight-matched single-blind parallel design. The study comprised a 6-day weight loss period (days 1-6), followed by a 3-day competition period (days 7-9). The participants in both the groups consumed 16 kcal/kg/day, including 1.6-1.7 g/kg of carbohydrates, 1.2-1.3 g/kg of protein, and 0.45-0.5 g/kg of fat during the 9-day period. The HMB group consumed 3 g/day HMB. Body composition measurement, isometric mid-thigh pull (IMTP), and a simulated boxing match were performed at baseline and on days 7, 8, and 9. Fasting blood samples were collected on the day before day 1 and on days 7, 8, and 9. Body mass was significantly decreased after the 6-day weight loss period (HMB group: baseline: 69.4 ± 11.2 kg, day 7: 67.1 ± 11.2 kg; PLA group: baseline: 68.6 ± 12.1 kg, day 7: 65.7 ± 11.5 kg, P < 0.05) while it was unchanged on the 3-day competition period in both the groups. Fat-free mass in the HMB group was maintained throughout the 9-day period (baseline: 56.7 ± 9.3 kg, day 7: 56.3 ± 8.7 kg, day 9: 55.8 ± 9.5 kg) whereas it significantly decreased on days 7 and 9 compared to the baseline in the PLA group (baseline: 55.2 ± 6.4 kg, day 7: 54.1 ± 6.6 kg, day 9: 54.0 ± 6.6 kg, P < 0.05). In the PLA group, the average and maximal heart rates in round 1 and the average heart rate in round 2 on days 8 and 9 were significantly lower than those at baseline, while these parameters were unchanged in the HMB group. The maximal force and the rate of force development in the IMTP remained unchanged among the different timepoints in both the groups. The blood biochemical parameters were similar at any timepoint between the PLA and HMB groups. HMB supplementation during acute weight loss may preserve fat-free mass and maintain heart rate response in subsequent simulated matches in well-trained boxers. In addition, HMB supplementation had a nonsignificant effect on glucose, fat, and protein metabolism during energy restriction.