(2) The first phase of Kefir, the second phase of the placebo group (hereinafter referred to as group B

(1) first-stage placebo and second-stage Kefir group (hereinafter referred to as group A).

28 days supplementation kefir drink (prepared by inoculating pasteurized 9.2% reconstituted skim milk with powder kefir starter culture and fermented at 37 °C for 16 h. The fermented milk was then pasteurized at 100 °C for 30 min and freeze dried. The powder kefir starter culture used for inoculation was composed of defined lactic acid bacteria strains which contains Lactobacillus fermentum DSM 32784 (LF26), L. helveticus DSM 32787 (LH43), L. paracasei DSM 32785 (LPC12), L. rhamnosus DSM 32786 (LRH10), and Streptococcus thermophilus DSM 32788 (ST30)), 200ml/day

We adopted a double-blind test in which the volunteers, based on their basal maximal oxygen consumption (VO2max). before and after intervention, the individual basal VO2max during pretest was used as a reference to adjust the individually appropriate exercise intensity to measure exhaustive endurance (85% VO2max) and recording the running time from begin to exhaust.

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 5 (E5), 10 (E10), 15 (E15), and 30 (E30) min during the exercise phase, and 20 (R20), 40 (R40), 60 (R60), and 90 (R90) min in the recovery phase. Serum lactate (mmol/L), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 5 (E5), 10 (E10), 15 (E15), and 30 (E30) min during the exercise phase, and 20 (R20), 40 (R40), 60 (R60), and 90 (R90) min in the recovery phase. Serum ammonia (umol/L), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 5 (E5), 10 (E10), 15 (E15), and 30 (E30) min during the exercise phase, and 20 (R20), 40 (R40), 60 (R60), and 90 (R90) min in the recovery phase. Serum CK (U/L), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).