Drinks with alkaline negative oxidation reduction potential improve exercise performance in physically active men and women.
Using of performance-enhancing aids has been documented since ancient times and such practices are not reserved for elite or Olympian-level athletes. Since many athletes are looking for ergogenic aids that do not have side effects and cannot be detected during drug testing, nutritional ergogenic aids, including carbohydrates, bicarbonates and dietary antioxidants, are promising alternatives. Athletes who engage in high-intensity exercise such as sprint cycling and swimming along with track events and team sports could be interested in ergogenic aids that buffer against lactic acid.
On the other hand, intense physical exercise increases oxidative stress, which leads to enhanced production of free radicals, a factor related to prolonged recovery and exercise-induced fatigue with antioxidant supplementation which can decrease biomarkers of oxidative stress and improve muscular performance in humans. Therefore, a dietary supplement with both buffering and antioxidant effects, could be of particular interest to both recreational and top-level athletes as an effective ergogenic aid. Negative oxidation reduction potential (NORP) alkaline water is often promoted as an antioxidant and anti-aging agent, with clear health benefits yet to be determined. Several recent studies showed anti-microbial activity of electrolyzed oxidizing water against microorganisms relevant in medicine. As an ergogenic aid, NORP alkaline water could be used by athletes in sports such as endurance running to combat the fatiguing effects of lactic acid. Moreover, the strong antioxidant potential of NORP water could be of particular interest for athletes to protect against the damaging effects of free radicals induced by exercise. However, to our best knowledge, no previous cross-sectional or longitudinal study examined the effects of NORP water on human performance. We investigated in a double-blind randomized cross-over trial, firstly, whether intake of the NORP drink improved running performance in young healthy active men and women, secondly, how many participants experienced adverse effects at follow up after this treatment. Therefore, in the current study we tested the hypothesis that an acute (7 days) intake of NORP would reduce the rate of blood lactate accumulation during and after exercise, increase the exhaustion time, increase serum buffering capacity and not increase prevalence of adverse effects.
MATERIALS AND METHODS
Both male and female athletes requesting a preparticipation medical examination at the TIMS Exercise Science Centre, Novi Sad, during November 2009, who were experienced in endurance training (> 2 years) and who were between 20 and 30 years of age (24.3 Â± 4.1 years), were candidates for inclusion in the study. They were not admitted to the study if any of the following criteria were present: a history of heart disease; musculoskeletal dysfunction; known metabolic disease; smoking; use of any performance-enhancing drugs or dietary supplements within the past 30 days; an impaired response to exercise test; and residence outside the city of Novi Sad, or unwillingness to return for follow-up. All participants were fully informed verbally and in writing about the nature and demands of the study as well as the known health risks. They completed a health history questionnaire, and gave their informed consent regarding their voluntary participation in the study. Upon initial recruitment, eleven (n = 11) participants (9 men and 2 women) met the criteria to take part in the study. All procedures were performed in accordance with the Declaration of Helsinki and the study was approved by the local IRB. The study was carried out at the Exercise Physiology Laboratory, part of Faculty of Sport Sciences and Tourism, Novi Sad, University of Metropolitan, Serbia.
Participants were randomized in a double-blind, cross-over design to receive the control drink and the NORP drink, with two single-week periods to study the efficacy of the NORP drink (at a dose of 1 L per day by oral administration) according to exercise rehydration guidelines. The NORP drink was supplied in bottles containing water, 2 g NORP, 6 g sucrose, 1-2 mg sodium per dose. The control drink was identically supplied and formulated except that it contained no NORP (Gatorade Sport Drink, San Diego, CA, USA). Subjects self-administered the drink before (30 minutes), during (every 15 min) and after each training session (until 45 min of recovery). The primary endpoint with respect to the efficacy in human performance was the proportion of participants achieving a significant (5%) improvement in running exhaustion time from baseline to 1 week. Additional analyses were done on the blood lactate change during and after exercise and on prevalence of side effects. All testing was conducted at the end of the first and at the end of the second week and the subjects were assessed on the same day with the tests performed in the same order. Participants were instructed to report on adverse effects of supplementation through an open-ended questionnaire at the end of the first and the second weeks of supplementation.
DIETARY CONTROL AND TRAINING
All subjects met a nutritionist who instructed them to maintain their normal dietary pattern throughout the study. During the supplementation regimen all subjects consumed similar standardized diet. Compliance was monitored by analyzing 3-d food records pre- and post-supplementation. Diet records were analyzed for daily caloric intake and composition using food analysis software package. During the trial (7+7 days) all subjects followed a similar training program. Subjects trained for 3 days per week on non-consecutive days. All subjects received a similar personalized training manual with prescribed exercise to be performed. All training sessions were performed at the Faculty’s athletic training facility and monitored by a certified strength and conditioning coach.
Subjects reported to the laboratory field at 10 a.m. after fast of between 10 and 12 h. Upon entering the laboratory, blood was drawn from the antecubital vein and analyzed for total antioxidant capacity (TAC) by the procedure of chemiluminescence (Boehringer Mannheim GmbH, Germany; cV%=8.2). Fasting blood also was obtained for measurement of glucose and bicarbonates and the sample was sent to the research laboratory, where glucose and bicarbonates were analyzed by standard enzymatic methods and an automated analyzer (Hitachi 704, Tokyo, Japan; cV%=13.0 and cV%=8.5, respectively). For all values, the first reading was discarded and the mean of the next three consecutive readings with a coefficient of variation below 15% was used in the study. A week before the study, the subjects performed a familiarization trial on the treadmill. In the 24 hours before the experiment, the subjects did not participate in any prolonged exercise or drink alcoholic and/or caffeine beverages. Before experimental sessions body mass, height, percentage of body fat, muscle mass and total body hydration from bioimpedance analysis were determined for each subject. Then, the subjects were instrumented for maximal oxygen consumption (VO2MAX) and telemetric heart rate (HR) assessment. Exercise test was performed according to the ramp protocol up to the maximal symptom-tolerated level using a treadmill system (Trackmaster TMX425C, Newton, USA). Gas-exchange data were collected throughout the exercise test using a breath-by-breath metabolic system (Vacu-Med CPX, Ventura, USA) with VO2MAX defined as the highest VO2 achieved during the test with data smoothed before calculating VO2MAX. The heart rate was continuously recorded with a heart rate monitor (Polar S810, Kempele, Finland). The modified rates of perceived exertion (RPE) were monitored during the test (at 3-min intervals), at the end of the test (RPEmax) and after 3 minutes of recovery. During the test (at 8.1 mph running speed) and after the test was completed, the blood was drawn from the fingertip and analyzed immediately for lactate by the procedures of reflectance photometry (Accutrend, USA; cV% = 12.4). The accuracy of the lactate analyzer was checked before each test using standards. The level of blood lactate measured in the third minute after the test was recorded as Lactrrec3, and the level of lactate measured 5 minutes after the test was recorded as Lactrec5.
The data are expressed as Means Â± SD. Statistical significance was assessed using Student’s t test for paired samples to evaluate the significance of differences between the values obtained. P values of less than 0.05 were considered to be statistically significant. The data were analyzed using the statistical package SPSS, PC program, version 16.0 (SPSS Inc., USA).