The Effects of Post-Exercise Consumption of a Kefir Beverage on Performance and Recovery During Intensive Endurance Training
OBJECTIVE: This study was designed to determine whether kefir accentuates the positive health benefits assessed by measures in fitness and/or body composition, as a measure of cardiovascular disease risk as well as the biomarker c-reactive protein (CRP). METHODS: Thirty-eight adult males and females aged 18-24 years were assigned to one of four groups: 1) endurance training + control beverage (ETC), 2) endurance training + kefir beverage (ETK), 3) active control + control beverage (ACC) or 4) active control + kefir beverage (ACK). The E groups (ETK and ETC) completed 15 weeks of structured endurance training. The AC groups (ACK and ACC) maintained their usual exercise routine. Additionally, each group was assigned to either a kefir (ETK and ACK) or a calorie/macronutrient matched placebo (ETC and ACC) beverage that was consumed twice per week. The kefir beverage and the control beverage were developed and manufactured in the Louisiana State University Creamery and were identical in ingredients used with the only difference being the fermentation of the milk used in the kefir beverage. Pre/post measures included: body mass and composition, waist hip ratio and 1.5 mile run. Serum CRP was measured using an ELISA (Alpco Diagnostics, Salem, NH). A MANOVA was used to identify significant interactions and significance was set at p<0.05. RESULTS: There was a significant time x training group interaction (p = 0.0124) with the E groups (ETK and ETC) experiencing an average of 4.11% improvement in 1.5 mile time. There were no significance interactions among groups with respect to all other outcome variable with the exception of serum CRP. Serum CRP increased over time (p=0.103). However, there was also a trend for a time x kefir effect(p = 0.0778). The ETK and ACK groups experienced less (21.18%, 5.45%) of an increase when compared to the ETC and ACC (22.36%, 64.71%). CONCLUSIONS: The endurance training was effective in improving 1.5 mile times and kefir supplementation may have been a factor in attenuating the increase in CRP that was observed over the course of the intervention period. This preliminary study suggests that kefir may be involved in improving the risk profile for cardiovascular disease as defined by CRP.
Keywords: kefir; endurance training; cardiovascular disease