ORIGINAL ARTICLE Impact of a soccer match on the cardiac autonomic control of referees Daniel Alexandre Boullosa • Laurinda Abreu • Jose ´ Luis Tuimil • Anthony Scott Leicht Received: 28 June 2011 / Accepted: 30 September 2011 / Published online: 14 October 2011 Ó Springer-Verlag 2011 Abstract The purpose of this study was to assess the effect of a soccer match on the cardiac autonomic control of heart rate (HR) in soccer referees. Sixteen Spanish regional and third division referees (11 males: 26 ± 7 years, 74.4 ± 4.1 kg, 178 ± 3 cm, Yo-Yo IR1 *600– 1,560 m; 5 females: 22 ± 3 years, 59.3 ± 4.8 kg, 158 ± 8 cm, Yo-Yo IR1 *200–520 m) participated with 24-h HR recordings measured with a Polar RS800 during a rest and a match day. Autonomic control of HR was assessed from HR variability (HRV) analysis. Inclusion of a soccer match (92.5% spent at [ 75% maximum HR) reduced pre- match (12:00–17:00 hours; small to moderate), post-match (19:00–00:00 hours; moderate to almost perfect), and night-time (00:00–05:00 hours; small to moderate) HRV. Various moderate-to-large correlations were detected between resting HRV and the rest-to-match day difference in HRV. The rest-to-match day differences of low and high-frequency bands ratio (LF/HF) and HR in the post- match period were moderately correlated with time spent at different exercise intensities. Yo-Yo IR1 performance was highly correlated with jump capacity and peak lactate, but not with any HRV parameter. These results suggest that a greater resting HRV may allow referees to tolerate stresses during a match day with referees who spent more time at higher intensities during matches exhibiting a greater LF/ HF increment in the post-match period. The relationship between match activities, _ V O 2 max and HR recovery kinet- ics in referees and team sport athletes of different com- petitive levels remains to be clarified. Keywords Autonomic nervous system Á Psychological stress Á Fatigue Á Recovery Á Monitoring Á Team sports Introduction Soccer referees have been examined at length regarding match activities and fitness characteristics (Castagna and D’Ottavio 2001; Catterall et al. 1993; D’Ottavio and Ca- stagna 2001; Tessitore et al. 2007; Weston et al. 2007). These studies have examined the distance and intensity of movements (Castagna and D’Ottavio 2001; D’Ottavio and Castagna 2001; Weston et al. 2007) and heart rate (HR) profile (Catterall et al. 1993; Tessitore et al. 2007; Weston et al. 2006) to assist in the referees’ preparation. While these characteristics may assist soccer referees, other physiological responses such as cardiac autonomic control have also been reported to be important for training- induced adaptations (Buchheit et al. 2010; Kiviniemi et al. 2007, 2010). For example, Kiviniemi et al. (2007) reported that daily exercise guided by HR variability (HRV) sig- nificantly improved cardiorespiratory fitness ( _ V O 2peak ) while pre-defined exercise training failed to alter _ V O 2peak Communicated by Susan A. Ward. D. A. Boullosa (&) Po ´s-Graduac ¸a ˜o Stricto Sensu em Educac ¸a ˜o Fı ´sica Graduac ¸a ˜o em Fisioterapia, Universidade Cato ´lica de Brası ´lia, QS 07, LT1 S/N, Sala 111, Bloco G, A ´ guas Claras, DF 71966-700, Brazil e-mail: d_boullosa@yahoo.es L. Abreu Lavadores, Vigo, Spain J. L. Tuimil Departamento de Educacio ´n Fı ´sica y Deportiva, Universidad de La Corun ˜a, Oleiros, Spain A. S. Leicht Institute of Sport and Exercise Science, James Cook University, Townsville, Australia 123 Eur J Appl Physiol (2012) 112:2233–2242 DOI 10.1007/s00421-011-2202-y