Natsue Koikawa

Effects of Oral Supplementation with Cystine and Theanine on the Immune Function of Athletes in Endurance Exercise: Randomized, Double-Blind, Placebo-Controlled Trial

Athletes become increasingly susceptible to infection with intense training that results in immune suppression. The immune state was investigated after administering cystine/theanine (CT), which has been reported to have an immune reinforcement effect, to athletes before training involving a prolonged period of intense exercise. Fifteen long-distance runners were each allocated to the CT or placebo group, and the test food was ingested for 10 d prior to the start of training. Clinical examinations were performed before and after the training. The results indicate a significant increase in the high-sensitivity C-reactive protein (hs-CRP) and neutrophil count in the blood, as well as a decreasing tendency for lymphocytes in the placebo group, but not the CT group. These observations suggest that the ingestion of CT contributed to suppressing the change in inflammatory response, prevented a decrease in the immune function, and prevented infection and reduced symptoms when infected associated with continuous intense exercise.

Delayed-onset muscle injury and its modification by wheat gluten hydrolysate

OBJECTIVE We investigated the pattern of delayed-onset muscle injury in well-trained athletes after a competitive half-marathon and the effects of post-race intake of wheat gluten hydrolysate (WGH). METHODS Thirty well-trained college runners with a best time of 14-15 min over 5000 m raced in a half-marathon. Thereafter, they were divided into three groups based on finish times and given 0 (control), 10, or 20 g of WGH. Blood biochemical parameters were monitored at -1 d, +1 h, +1 d, and +2 d after the race. Data selected according to finish times and biochemical parameters were then analyzed. RESULTS Plasma creatine kinase activity peaked at 1 d after the race in the control group and correlated with post-race white blood cell counts. The post-race elevation of creatine kinase activity was dose-dependently suppressed by WGH. CONCLUSION Delayed-onset muscle injury peaked in well-trained distance runners at 1 d after a half-marathon and was dose-dependently suppressed by a post-race intake of WGH.

Preventive Effect of Lactoferrin Intake on Anemia in Female Long Distance Runners

This study investigated whether intake of lactoferrin (LF) would improve or prevent anemia in female long distance runners who were training during the summer season and had a high risk of iron-deficiency anemia. Sixteen female long distance runners were divided into a group taking LF and iron (the LF group) and a group that only took iron (the control group) for 8 weeks. In the control group, the ferritin, serum iron, and red blood cell count were significantly lower than before treatment. In the LF group, the hematology data showed no significant change during the 8 weeks. The red blood cell count was significantly higher in the LF group than in the control group. The blood lactate level following a 3,000-m pace run of the control group was also significantly higher than that of the LF group. These observations suggest the possibility that intake of LF increases the absorption and utilization of iron and would be useful in the prevention of iron deficiency anemia among female long distance runners.

Stress Fracture Influences Bone Resorption marker (u-NTX) in Female Long Distance Runners

In this study, we aim to clarify the influence based on bone resorption markers at onset of stress fracture. Also, we will clarify the state of the bone resorption markers of female long distance runners who have a history of stress fracture and also ones who routinely practices running long distances. Participants comprised 19 female long distance athletes. The survey period was 2011-2014, and we measured u-NTX as a bone resorption marker at least twice a year, taking the mean±SD of the periodic measured values without stress fracture as the mean value. Measurements were collected sample when stress fractures developed. 132 u-NTX measurements were taken from 19 participants. As a result, the average was 41.03±12.31 nmolBCE/mmolCRE (Q1: 33.15, Q2: 40.55, Q3: 47.95). In six of the 19 participants, u-NTX could be measured following a stress fracture. The mean value of u-NTX for those participants was 40.16±9.10 nmolBCE/mmolCRE, increasing to 64.08±16.07 nmolBCE/mmol CRE with the stress fracture (p<0.01). The findings showed that, in adult female long distance runners, u-NTX values when there was no stress fracture were within the standard value for mean premenopausal women, but increased when the athletes suffered from a stress fracture.