Author(s): CHEN, T.C.1, CHOU, T.Y.1, NOSAKA, K.2, Institution: NATIONAL TAIWAN NORMAL UNIVERSITY, Country: TAIWAN, Abstract-ID: 518

INTRODUCTION:
Our previous study [Chou et al. Int J Environ Res Public Health. 2021;18:4134] showed that muscle damage and performance measures took 4-5 days for female soccer players to return to the baseline following a 90-min Loughborough Intermittent Shuttle Test (LIST) that mimics running activities in a soccer match. The study also found that the total distance covered in the LIST was 5-7% shorter for the second to sixth LISTs than the first LIST when the LIST was performed 6 consecutive days, and decreases in muscle strength and other performance measures were still evident at 5 days after the sixth LIST [Chou et al. 2021]. No study has investigated how many days are necessary between matches for good performance with minimum muscle damage, thus the present study compared four different intervals between three LISTs for changes in muscle damage and performance parameters.
METHODS:
Thirteen well-trained female university soccer players performed three bouts of 90-min (15-min x 6 sets with 3-min between sets) LIST with four different intervals between bouts; one (1d), two (2d), three (3d) and four days (4d), with more than 12 weeks between bouts in a counterbalanced order. Heart rate (HR), blood lactate (LA), rating of perceived exertion (RPE) and distance covered in each LIST were measured. Changes in several muscle damage markers [maximal voluntary isometric torque of the knee extensors (MVC-KE) and flexors, muscle soreness, plasma creatine kinase activity and myoglobin concentration], and performance parameters [countermovement jump, 30-m sprint, 30-m timed hop test, agility T-test, 6x10-m shuttle run, Yo-Yo intermittent recovery test level 1 (YYIR1)] before the first LIST, 1 hour after each LIST, and 1-5 days after the third LIST were compared among the conditions by a two-way of repeated-measures ANOVA.
RESULTS:
The total distance covered in the first two LISTs (10,268±412m) was not different among the conditions, but that was 6-9% (P<0.05) shorter in the third LIST for the 1d and 2d conditions than the 3d and 4d conditions. HR, RPE and LA concentration in the three LISTs were not different (P>0.05) among the conditions. Changes in all measures were smaller (P<0.05) in the 3d and 4d conditions (e.g., the decrease in MVC-KE at 1 day after the third LIST was -13±4% and -10±3%, respectively) when compared with the 1d and 2d conditions (-20±7%, -18±5%). Performance parameters showed smaller (P<0.05) changes in the 4d (e.g., the decrease in YYIR1 at 1 day after the third LIST was -9±3%) and 3d (-13±6%) conditions when compared with the 1d (-19±4%) and 2d (-20±8%) conditions.
CONCLUSION:
These results suggest that muscle damage and fatigue accumulate when LIST was performed three consecutive days or every other day, but if more than three days were inserted between matches, this could be minimized. However, even for the 4 days interval, some extent of muscle damage is inevitable, which possibly taxes the body for several days.