1. Keshia Brennan, Rachael Dawe, Alice Fisher-Edwards & Lisa Board
 Effect of Pre-Cooling on Intermittent Sprint Performance in Female Rugby Players during Luteal Phase of Menstrual Cycle
Keshia Brennan, Rachael Dawe, Alice Fisher-Edwards & Lisa Board
Department of Sport and Exercise, University of Sunderland, Sunderland, SR1 3SD
Introduction
Thermal homeostasis and sport performance may be influenced by phase of the female menstrual cycle. Current research suggests time to exhaustion is reduced during prolonged exercise in hot conditions during the luteal phase (LP) of menstrual cycle (Garcia, et al, 2011). Luteal phase associated with increase in progesterone and slight and transient increase in basal body temperature.
Few studies have assessed repeated sprint performance during menstrual cycle. Current research suggests mean work over a series of sprints and oxygen consumption between sprints is increased in LP (Middelton and Wenger, 2006). One study has investigated repeated sprint performance in hot conditions. Authors concluded repeated sprint performance was not affected by phase of menstrual cycle in unacclimatized games players although oral contraceptive use did affect performance.
Pre-cooling shown to enhance performance in the heat by (Wegmann, et al., 2012). Numerous pre-cooling interventions are available. Some reduce skin temperature (jackets), others reduce core temperature (cold ingestion), while others have a contribution to both skin and core temperature (cold water immersion) (Duffield et al,. 2010). Recent research showed no effect on repeated sprint performance in female following ice ingestion (Zimmermann and Landers, 2014) . By means of effective body cooling, water immersion appears to lead to a rapid and large reduction of skin and core temperature, which can strongly influence performance (Ross et al., 2013). Given the increase in core temperature during the LP of the menstrual cycle we speculated a pre-cooling intervention (water immersion) may enhance repeated sprint performance and physiological responses in female athletes in hot conditions (26-28oC).
Aim - to investigate the effect of a 15 min pre-cooling intervention using water immersion (14oC) on physiological responses and repeated sprint performance in the heat during the luteal phase of the menstrual cycle .
Method
Research Design – Randomised, controlled, within-subject crossover trial. Study approved by University of Sunderland Research Ethics Committee.
Participants- 9 female, healthy, club-level rugby players (age, 26.6 ± 6.5 years, stature, 1.66 ± 0.04 m, body mass , 77.4 ± 17.3 Kg, V O2max, 29.5 ± 6.3 ml.Kg-1.min-1).
Protocol- Participants completed a 40 minute intermittent sprint cycling protocol (Castle, et al., 2006) (20 x 5s sprint, 115 s active recovery) on a Lode Excalibur cycle ergometer in the heat . Baseline trial followed by a control (no pre-cooling) and an experimental (pre-cooling) trial in a randomised order. 15 min water immersion pre-cooling.
Measures – HR, rectal temperature (Trec), RPE, mean power output (MPO), peak power output (PPO).
Discussion
PPO, MPO and POmin all lower following pre-cooling intervention (Figure 1). Wide inter-individual variability and results did not reach significance. (P>0.05)
POmin was significantly lower over first 5 and 10 sprints following pre-cooling intervention (P>0.05). We speculate a lower muscle temperature following pre-cooling impeded anaerobic performance (Ross et al., 2013).
Core temperature was marginally lower after the pre-cooling intervention (Figure 2) (P >0.05).
Results indicate no significant differences in PPO or MPO between pre-cooling and control conditions . This is consistent with research evidence from repeated sprints in male athletes (Wegmann, et al., 2012).
Conclusion
Pre-cooling had no effect on repeated sprint performance in the heat in a group of unacclimatized amateur female rugby players .
Future Research - Scope exists to extend the current research evidence on repeated sprint performance in the heat in female athletes at different stages of the menstrual cycle and further explore the effect, if any, of contraceptive use. This study used amateur athletes, therefore studies which compare repeated sprint performances in elite athletes and across different sports would be of interest.
Results
Figure 1: PPO, (a) MPO (b) and POmin (c) values (mean ± SD) during the intermittent sprint protocol in hot conditions in control and pre-cooling conditions. No significant differences between pre-cooling and control trials (P > 0.05).
Figure 2: Heart rate (a), Tc (b) and RPE (c) values (mean ± SD) during the intermittent sprint protocol in hot conditions in control and pre-cooling conditions. No significant differences between pre-cooling and control trials (P > 0.05).
References
Duffield, R., Green, R., Castle, P., Maxwell, N. (2010). Precooling can prevent the reduction of self-paced exercise intensity in the heat. Medicine and Science in Sports and Exercise. 42 (3):
Garcia, A. M. C., Lacerda, M. G., Fonseca, I. A. T., Reis, F. M., Rodrigeus, L. O. C., Silami-Garcia, E. (2006). Luteal phase of the menstrual cycle increases sweating rate during exercise. Brazilian Journal of Medical and Biological Research. 39 (9):
Middleton and Wenger (2006). Effects of menstrual phase on performance and recovery in intense intermittent activity. European Journal of Applied Physiology, 1,53-8..
Ross, M., Abbiss, C., Laursen, P., Martin, D., Burke, L. (2013). Precooling methods and their effects on athletic performance: A systematic review and practical applications. Sports Medicine. 43 (6):
Wegmann, M., Faude, O., Poppendieck, W., Hecksteden, A., Frohlich, M., Meyer, T. (2012). Pre-cooling and sports performance: A meta-analytical review. Sports Medicine. 42 (7):
Zimmermann and Landers (2014). Effect of ice ingestion n female athletes performing intermittent exercise in hot conditions. European Journal of Sport Sciences, 14, 1-7.