TEMPORAL SPECIFICITY IN ADAPTATIONS TO HIGH-INTENSITY EXERCISE TRAINING

Objective: The purpose was to test the hypothesis that lime to exhaust ion and oxygen deficit in high-intensity exercise at a particular time of day would be influenced by training regularly at that time of day. Methods: Over a 5-wk period, 12 college-age women performed 20 high-i ntensity exercise training sessions. On Mondays, they performed four 2 -min bouts of cycling at 2.5 W.kg(-1) with 4-min recoveries: on Tuesda ys and Thursdays, eight 1-min bouts at 3.0 W.kg(-1) with 2-min recover ies: and on Wednesdays, three 3-min bouts at 2.2 W.kg(-1) with 2-min r ecoveries. Six participants (a.m.-trained group) were randomly assigne d to train in the morning (a.m.) and six others (p.m.-trained group) t rained in the afternoon (p.m.). Upon completion of training, all parti cipants were tested in both the a.m, and p.m. (random order) at the sa me times as training sessions had been scheduled. Tests involved exhau stive efforts at 2.6 W.kg(-1). Results: Results of a repeated measures ANOVA revealed a significant time of day of training X time of day of testing interaction effect on time to exhaustion (F-1,F-10 = 8.29, P = 0.02). This suggested that the time of day of training affected the a.m.-p.m. pattern in time to exhaustion. Time to exhaustion for the a. m.-trained group was 398 +/- 258 s in the a.m. test and 351 +/- 216 s in the p.m. test (P = 0.07). The p.m.-trained group had significantly higher values in the p.m. test compared with the a.m. test (422 +/- 25 2 s vs 373 +/- 222 s; P = 0.03). here was also a significant interacti on effect on oxygen deficit (F-1,F-10 = 8.03, P = 0.02). This suggeste d that the time of day of training affected the a.m.-p.m. pattern in a naerobic capacity. Oxygen deficit for the a.m.-trained group was 64 +/ - 24 mL.kg(-1) in the a.m. test and 50 +/- 11 mL.kg(-1) in the p.m. te st (P = 0.10). The p.m.-trained group had significantly higher values in the p.m. rests (64 +/- 24 mL.kg(-1) vs 50 +/- 11 mL.kg(-1): P = 0.0 1) compared to the a.m. tests. Conclusions: These results demonstrate that there is temporal specificity in training to increase work capaci ty in high-intensity exercise. Greater improvements can be expected to occur at the time of day at which high-intensity training is regularl y performed.