Original Article http://mjiri.tums.ac.ir Medical Journal of the Islamic Republic of Iran, Vol. 27, No. 3, Aug 2013, pp. 141-146 Effects of probiotic yogurt on performance, respiratory and digestive systems of young adult female endurance swimmers: a randomized controlled trial Nahid Salarkia1, Leili Ghadamli2, Farid Zaeri3, Leila Sabaghian Rad4 Department of Food and Nutrition Policy and Planning Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Received: 6 October 2012 Revised: 23 Dec 2012 Accepted: 7 Jan 2013 __________________________________________________________________________________________ Abstract Background: To determine the effects of probiotic yogurt on performance and health status of young adult female endurance swimmers. Methods: In a randomized controlled trial, 46 endurance swimmers girls with mean age of 13.8 ±1.8 years, weight of 48.6±7.5kg and height of 159±5.6cm, were studied. Subjects were randomly assigned into two groups, receiving either 400 ml probiotic yogurt (intervention group) or ordinary yogurt (control group) daily for 8 weeks. At the beginning and at the end of the study, the 400-m free swimming record was done and the Harvard Step test was employed to measure VO max. Statistical analysis of the data was performed using SPSS soft- 2 ware. This trial has been registered with IRCT ID of IRCT2012122311849N1. Results: Average changes in the records of the intervention and control groups were 3.9 and 0.5 seconds, re- spectively (p= 0.22). The intervention group complained of dyspnea for 2.4 days and the value for the control was 4.4 days (p=0.024). Values for ear pain were 0.5 and 1.6 days (p=0.008) respectively. The average number of episodes of respiratory infection in the intervention group was 0.9 day, which was statistically fewer than that in the control group (1.4 days), P=0.009. Conclusions: A reduction in the number of episodes of respiratory infections and duration of some symptoms such as dyspnea and ear pain was observed. Due to the reduction in upper respiratory tract infections of the athletes following intake of probiotic yogurt, improvement in VO2max is possible. Keywords: Probiotics, Yogurt, Athletic performance, Respiratory infections, Gastrointestinal diseases, Swimming. ________________________________________________________________________________________ illnesses such as upper respiratory tract in- Introduction fections and gastrointestinal symptoms can Elite athletes undertaking severe and in- seriously impair athlete’s performance to tense exercises may suffer from an in- train (8). It is also known that intensive ex- creased risk of upper respiratory tract infec- ercise and strenuous physical training caus- tions and gastrointestinal symptoms (1-7). es a rise in chronic exhaustion and a de- It is important for athletes to stay healthy crease in athlete’s efficiency (9,10). Im- during training period and competition but paired athletic performance and fatigue in _______________________________________________________________________________________________________ 1. (Corresponding author) Research Assistant, Dept. of Food and Nutrition Policy and Planning Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. [email protected], [email protected] 2. MSc in Nutrition Sciences, Shahid Beheshti University of Medical Sciences, International Branch, Tehran, Iran. [email protected] 3. Assistant Professor, Dept. of Biostatistics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Iran. [email protected] 4. Assistant Professor, Islamic Azad University, Science and Research Branch, Tehran, Iran. [email protected] Probiotics and health status in swimmers well trained athletes and its relation to in- 11 to 17 years who had taken part in the fections and decreased mucosal immunity national 400 and 800 meter crawl swim- has been reported (11). Based on reports, ming competitions of 2009. Subjects had 89% of presentations of elite athletes were exercise for three times a week. The associated with the viral or bacterial upper swimming distance was 3800 meter in 2 respiratory tract infection (12). hour and 30 minutes for each session. In- Illness during training and competition clusion criteria were being healthy and hav- may negatively affect athletic performance ing the 400 meter crawl swimming time (13). Therefore, identifying strategies to less than 6 min. and 20 Sec (20). Exclusion improve host resistance and minimizing the criteria included acute gastrointestinal risk of illnesses that may compromise ath- symptoms such as: diarrhea, vomiting and letic performance, is necessary. stomachache and intake of antibiotics with- Probiotic bacteria being defined as live in the past two months before the study. food ingredients occur naturally in fer- This study was approved by the University mented food products such as yogurt (14). Human Research Review Committee and Probiotics may improve athlete’s efficiency the National Nutrition and Food Technolo- by maintaining healthy gastrointestinal gy Research Institute Ethics Committee. tract function, reducing susceptibility to This study has been registered in the IRCT illnesses such as acute infectious diarrhea website with the ID of IRCT20121223 and its associated symptoms, enhancing 11849N1. host resistance to upper respiratory tract infections and improved immune function Procedures: In this randomized controlled (1,14–17). trial the subjects were randomly assigned Many studies have been made on the bene- into two groups as follows: group 1) Re- ficial effects of the probiotics for human ceiving 400 ml of probiotic yogurt contain- health including effects on gastrointestinal ing 4 × 1010 cfu/ml (Colony forming unit tract function and diseases, immune re- per millimeter) comprising of Lactobacillus sponse, hyperlipidemia, hypertension, and Acidophilus SPP, Lactobacillus allergic conditions within such groups as Delbrueckii Bulgaricus, Bifidobacterium children, infants, adults and the elderly (8, Bifidum, and Streptococcus Salivarus 12, 18, 19). Although, there is an increas- Thermnophilus, (n=23) and group 2) Re- ing interest in the effect of probiotics on the ceiving similar dose of ordinary yogurt, as incidence of respiratory tract infections a control (n=23). (18), few studies have been carried out on The 400 meter free swimming record was the role of probiotics in the improvement of conducted, and Harvard step test was also athletes’ capability during exercise period employed to measure VO max .The athlete 2 and competitions (8, 11). The initial inves- stepped up and down off a 41cm high tigations in athletes have thus far not been bench for 3 minutes at a rate of 22 convincing (8). steps/minute. On finishing the test the This study was performed on elite athletes, number of heart beats was counted for 15 who are more susceptible to infection. This seconds. The number of beats was multi- study was carried out to determine the ef- plied in 15 seconds by 4 to give the "step fect of receiving probiotic yogurt on the test pulse rate". This final value was used status of respiratory and digestive system to assess the athlete's VO max in 2 of young adult female swimmers in sum- ml/kg/min (21). This test was performed at mer training period. the beginning and at end of week eight. All subjects were asked to record the digestive Methods symptoms (such as stomachache, vomiting Subjects: The studied subjects were 46 fe- and diarrhea), respiratory infections (such male endurance swimmers aged between as rhinitis, fever, sore throat, cough, chest http://mjiri.tums.ac.ir 142 MJIRI, Vol. 27, No. 3, Summer, Aug 2013, pp. 141-146 N. Salarkia, et al. Table 1. Mean of anthropometry data and exercise distance in subjects, at the beginning of the study. Study group Index Probiotic Control p n=23 n=23 (Mean±SD) (Mean±SD) Age (year) 13.7±1.9 14.0±1.8 0.636 Weight (kg) 46.7±6.3 50.4±8.3 0.097 Height (cm) 158.3±5.1 159.9±6.2 0.328 Exercise distance (m) 11358.7±152.0 11436.9±139.2 0.075 Table 2. Mean of the change rate of performance indices in subjects. Study group Index’s change rate Probiotic Control p n=23 n=23 (Mean±SD) (Mean±SD) 400 m crawl swimming record (min-sec) -0.039±0.09 -0.005±0.02 0.222 VO2max (ml/kg-1.min-1) 0.56±096 0.01±055 0.022 Table 3. Average duration of respiratory infections based on study groups in subjects. Study group Duration of exposure respiratory Probiotic Control p infections(day) n=23 n=23 (Mean±SD) (Mean±SD) Rhinitis (day) 3.2±2.5 4.3±3.0 0.268 Fever (day) 0.5±0.7 1.0±0.9 0.152 Sore throat (day) 0.8±0.9 1.8±1.7 0.08 Cough (day) 2.0±2.4 2.9±3.3 0.348 Dyspnea (day) 2.4±2.6 4.4±2.8 0.024 Ear pain (day) 0.5±0.9 1.6±1.7 0.008 ailing breath by sound, ear pain), the extent Results of exercise per meter, the intake of medi- The mean age, weight and height of sub- cine, and quantity of the consumed food- jects were 13.8 ±1.8 years, 48.6±7.5 kg and stuff product which had been recommend- 159 ±5.6 cm, respectively. Mean of anthro- ed, on the provided questionnaires, daily. pometry and the extent of exercise per me- The subjects were advised to refrain from ter, has been shown in Table 1. Table 2 other probiotic products which were out- shows the average change in the perfor- side the project plan. mance indices including 400 m crawl swimming record and VO2max in subjects Statistical analysis: Statistical analysis of during the study. The average changes in the data was performed using SPSS version the records of the intervention and control 17 (Chicago, IL, USA). Data was presented group were 3.9±0.09 and 0.5±0.02 seconds, as mean with standard deviation (SD). Data respectively (p= 0.22). On the other hand, were checked for normality. The differ- the change in VO max in the intervened 2 ences between the groups were tested using group was 0.56±0.096, and in the control the t test as a parametric and Mann Whit- group was 0.01±0.55, ml/kg-1.min-1; that ney U test as a nonparametric test. was statistically significant in both groups Comparisons between the 2 groups was (p=0.02). Table 3 shows the average dura- performed using 2-sided statistical tests. tion of respiratory infections in subjects. Differences were considered significant at On the average, the intervention group p< 0.05. complained of dyspnea, as a symptom of respiratory infection, for 2.4±2.6 days; the MJIRI, Vol. 27, No. 3, Summer, Aug 2013, pp. 141-146 143 http://mjiri.tums.ac.ir Probiotics and health status in swimmers Table 4. Average duration of digestive disorders based on study groups in subjects. Study group Duration of exposure digestive Probiotic Control p disorders n=23 n=23 (Mean±SD) (Mean±SD) Diarrhea(day) 1.0±1.5 1.2±1.3 0.394 Vomiting(day) 0.8±0.9 1.0±1.5 0.981 Stomachache(day) 1.4±1.3 2.0±1.1 0.102 Table 5. Average number of episodes of respiratory infections and digestive problems in subjects. Study group p Average number of episodes of Probiotic Control problems n=23 n=23 (Mean±SD) (Mean±SD) Digestive disorders (number) 0.9±08 1.6±0.8 0.057 Respiratory infections (number) 0.9±0.8 1.4±0.6 0.009 value in the controls was 4.4±2.8 days regard to the average duration of symptoms (p=0.024). For ear pain, another symptom of respiratory infection or digestive disor- of respiratory infection, the value were ders. 0.5±0.9 and 1.6±1.7 days (p=0.008). As shown in Tables 3 and 4, after 8 weeks of Discussion intervention, no significant difference was This study investigated the effect of pro- noted between the 2 groups with regard to biotic yogurt on performance, status of res- the average duration of symptoms of res- piratory and digestive system in young piratory infections including rhinitis, fever, adult women endurance swimmers. sore throat, cough, and also digestive dis- An important finding in this study was the orders such as diarrhea, vomiting and reduction in the number of episodes of res- stomachache. piratory infections and in duration of some Table 5 presents average number of epi- of its symptoms such as dyspnea and ear sodes of respiratory infection and digestive pain, following the consumption of probi- disorders in subjects. The average number otic yogurt. However, by consumption of of episodes of respiratory infection in the such type of yogurt, the decrease in diges- intervention group was 0.9±0.8 day, which tive disorders of the athletes did not appear was statistically fewer than that in the con- meaningful. According to the results of the trol group (1.4±0.6 days); the difference present study a non-significant decline in was statistically significant (p=0.009). In the records of 400 m crawl swimming was addition, the average number of episodes of observed. digestive disorders was 0.9±0.8 in the in- In a review of studies on probiotics, while tervention group and 1.6±0.8 in the con- probiotics have not been reported to direct- trols that did not reach statistical signifi- ly affect athletic performance, probiotics cance (P=0.57). Average duration of symp- help athletes avoid becoming ill from se- toms of respiratory infections in the inter- vere and intense exercises and increase the vention group was 4.0±2.7 days which was chances that athletes will stay healthy (1, not statistically fewer than that in the con- 14). trol group (5.4±3.3 days). Average duration In the present study, mean rate change of of symptoms of digestive problems in the 400 m crawl swimming record before and intervention and control group was 1.8±1.7 after taking the probiotics yogurt was simi- and 2.5±1.6 days, respectively. After 8 lar to results of Cox in 2007. In his study weeks of intervention, no significant differ- on twenty healthy elite male distance run- ence was found between the 2 groups with ners, he found a reduction in the number of http://mjiri.tums.ac.ir 144 MJIRI, Vol. 27, No. 3, Summer, Aug 2013, pp. 141-146 N. Salarkia, et al. days and severity of respiratory illness in a Conclusion cohort of highly trained distance runners. It is concluded that consumption of probi- He suggested that the effect of amount of otic yogurt results in a reduction in the yogurt consumed and the level of weekly number of episodes of respiratory infec- training were more important among all tions and in duration of some of its symp- factors (2). toms such as dyspnea and ear pain; the re- According to the results of our study a sig- duction in digestive disorders did not reach nificant increase in VO2max was observed statistical significance. Intake of probiotic which is similar to previous studies (22- yogurt also resulted in a significant im- 24). Previous research have indicated a proved in VO max and a non-significant 2 decrease in severity and duration of colds decline in the records of 400 m crawl in both children (25,26) and adults (27). swimming. Possibly, improvement in The present study confirms the previous VO max is due to the reduction of upper 2 findings that probiotics have similar effects respiratory tract infections (reduction in the in athletes in training. number of episodes of respiratory infec- In our study, the number of subjects with tions and in duration of some of its symp- upper respiratory tract infections was lower toms) of athletes following intake of probi- than that observed in the previous studies otic yogurt. The results also showed that on marathon runners (8, 28). This is possi- the athletes who take probiotics stay health- bly due to differences in the season of the ier overall. It is necessary to plan the ath- study (summer vs. winter), age groups (14 lete’s regimen carefully and to make sure vs. 40 years), type of sport (swimming vs. they eat properly. We recommend further marathon) and intervention period. studies using a larger sample size, longer Our findings on the average number of period time, different sexes and age groups, episodes of respiratory infection are in and different seasons to find the effects of agreement with those of Heath et al (29). In probiotic on the health and performance of our study the number of healthy days in the athletes. intervention group was higher than the con- trol group; it was similar to previous stud- Acknowledgements ies (8). One possible explanation is that the We would like to thank Professor Andro present study has been carried out in sum- Nichols from Sport Medicine Department mer, with a lower chance of colds and flu. of Hawaii University for his advice and Previous studies were carried out in winter- valuable comments to design and imple- time (18, 19, 25,30). mentation of the study, all students who However the Cox study on 20 healthy male participated, their families, coaches and the long-distance runners to examine the effect staff from Tehran swimming school for as- of probiotic capsules containing sistance in the field survey. Lactobacillus fermentum showed a significant reduction in the actual number of respiratory infections, the number of References episodes in the probiotics group was less 1. West NP, Pyne DB, Peake JM, Cripps AW. than half the corresponding number in the Probiotics, immunity and exercise: a review. Exerc immunol Rev 2009; 15:107-26. control group (2). 2. 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