RESEARCH EXERCISE SCIENCESPORT EXERCISE SCIENCE

BY FRASER HOUSTON AND CLARE PHEASEY, DEPARTMENT OF EXERCISE AND SPORT SCIENCE, MANCHESTER METROPOLITAN UNIVERSITY

INTRODUCTION Various studies have found that soccer players, referees and assistant referees perform less high-intensity running in the initial phase of the second half compared with the first half of the match. Such findings suggest that the normal routine of resting for the entire 15-minute half-time interval in soccer may not provide optimal preparation for the second half. Mohr and colleagues investigated the effects of rest and

moderate re-warm-up during half-time on initial performance during the second half of a soccer match (1).These authors observed a significant negative correlation between the decrease in sprint performance and decrease in muscle temperature at half-time. However, the methods used to re-warm participants were

limited in number and vague in description (either no activity or running exercise at moderate intensity).

PURPOSE To further investigate the effects of re-warm-up routines on sprint performance at the start of the second half.

METHOD

With institutional ethics approval, nine university first-team soccer players (mean±standard deviation (SD): age 20.5±2 years, body mass 4.1±4.2kg and stature 176.4±8.4cm) participated in three trials separated by at least 2 days of non-activity within a 2-week period. Heart rate (HR) was recorded throughout each trial using the Polar Team System. Participants performed a standardised 20-minute warm-up consisting of dynamic stretching, sprinting and basic passing. A repeated sprint test (RST1) consisting of three maximal sprints

separated by about 30 seconds of walking, with timing gates placed at 5m, 10m and 15m, followed the warm-up. A 45-minute 11-a-side soccer match was then played, with all participants occupying an outfield position. Participants moved to the laboratory at the onset of half-time (~1 minute transition). The 15-minute half-time period consisted of 7 minutes of seated rest for all participants,

followed by 7 minutes of a routine. Participants were randomly assigned to one of three half-time routines: (i) seated rest (SR); (ii) cycling at 50–60% of maximum heart rate (HRmax) (C50); or (iii) cycling at 70–80% HRmax (C70). Approximately 1 minute after half-time, a second repeated

warm up and stretch 0 time (minutes) RST1 20 30 Figure 1: Experimental protocol www.sportEX.net 45 min 11-aside soccer game 75

half time routine

RST1 90 100

THE EFFECT OF HALF-TIME RE-WARM-UP ROUTINES ON SECOND-HALF SPRINT PERFORMANCE IN SOCCER

100 100 100 100 100 100 100

RST1 SR C60 C70

*

5m

10m

15m

Figure 2: Percentage change in sprint performance (RST2 (meantime) as percentage of of RST1 (mean time)) * significant difference between RST1 and RST2 values (P<0.05)

sprint test (RST2) was performed. All participants repeated all three routines within a 14-day period.

DATA ANALYSIS

A repeated measures one-way analysis of variance (ANOVA) followed by a Bonferroni correction examined changes in RST times.

RESULTS

All routines RST2 times were slower over all distances than RST1. In routine SR, RST2 times were significantly slower compared with RST1 times over 5m (P<0.05; Fig. 2). RST2 times over 10m and 15m showed no significant difference between the three routines.

CONCLUSION

Consistent with Mohr and colleagues (1), inactivity during a half-time period decreased

5m repeat sprint performance in comparison with pre-match performance. However, there was no significant difference in sprint performance between warm-up and re-warm-up when cycling at 50% or 70% of HRmax during the half-time period. Thus, in order to maintain 5m pre-match sprint performance, a period of active re-warm-up is more appropriate than non-activity; however, there is no interaction effect for the intensity of active re-warm-up.

Reference 1. Mohr M, Krustrup P, Nybo L, Nielsen JJ, Bangsbo J. Muscle temperature and sprint performance during soccer matches: beneficial effect of re-warm-up at half-time. Scandinavian Journal of Medicine and Science in Sports 2004;14:156–162

21

% of RST1 sprint performance