Milk or Kefir, in Comparison to Water, Do Not Enhance Running Time-Trial Performance in Endurance Master Athletes

• Published in: Nutrients Vol. 16; no. 5; p. 717
• Main Authors: Gross, Kristen N, Harty, Patrick S, Krieger, Joesi M, Mumford, Petey W, Sunderland, Kyle L, Hagele, Anthony M, Kerksick, Chad M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.03.2024; MDPI
• Subjects: Analysis; Animals; Athletes; Biomarkers; Cross-Over Studies; Energy consumption; Exercise; Female; Fitness training programs; Humans; Inflammation; Kefir; Male; Males; Milk; Physical Endurance; Physical fitness; Polyesters; Probiotics; Proteins; recovery; Running; Surveys; Water; athletes; recovery; kefir; probiotics
• ISSN: 2072-6643; 2072-6643
• DOI: 10.3390/nu16050717

This study compared flavored kefir (KFR) and flavored milk (MLK) as a recovery drink in endurance master athletes. Using a randomized, placebo-controlled, non-blinded crossover design, 11 males and females completed three testing visits whilst acutely ingesting either KFR, MLK, or water as a placebo (PLA). KFR supplementation occurred for 14 days before the KFR-testing day, followed by a 3-week washout period. Testing visits consisted of an exhausting-exercise (EE) bout, a 4-h rest period where additional carbohydrate feeding was provided, and a treadmill 5 km time trial (TT). The Gastrointestinal Symptom Rating Scale (GSRS) survey was assessed at four timepoints. Blood was collected at baseline and after the TT and was analyzed for I-FABP levels. No significant difference (PLA: 33:39.1 ± 6:29.0 min, KFR: 33:41.1 ± 5:44.4 min, and MLK: 33:36.2 ± 6:40.5 min, = 0.99) was found between the groups in TT performance. The KFR GSRS total score was significantly lower than the PLA after EE ( = 0.005). No differences in I-FABP were observed between conditions. In conclusion, acute KFR supplementation did not impact TT performance or I-FABP levels but may have reduced subjective GI symptoms surrounding exercise when compared to MLK or PLA.