Phase One2017 NEW!
Background: Female soccer has grown extensively in recent years, however differences in gender-specific physiology have rarely been considered. The female reproductive hormones which rise and fall throughout the menstrual cycle, are known to affect numerous cardiovascular, respiratory, thermoregulatory and metabolic parameters, which in turn, may have implications on exercise physiology and soccer performance. Therefore, the main aim of the present study was to investigate potential effects of menstrual cycle phase on performance in soccer specific tests.
Methods: Nine sub elite female soccer players, all of whom have menstrual cycles of physiological length; performed a series of physical performance tests (Yo-Yo Intermittent endurance test (Yo-Yo IET), counter movement jump (CMJ) and 3x30 m sprints). These were conducted at distinct time points during two main phases of the menstrual cycle (early follicular phase (FP) and mid luteal phase (LP)) where hormones contrasted at their greatest magnitude.
Conclusion: The results of this study are in support of a reduction in maximal endurance performance during the mid LP of the menstrual cycle. However, the same effect was not observed for jumping and sprint performance. Therefore, consideration of cycle phase when monitoring a player's endurance capacity may be worthwhile.
Female soccer has grown extensively in recent years, however differences in gender-specific physiology have rarely been considered. The female reproductive hormones which rise and fall throughout the menstrual cycle, are known to affect numerous cardiovascular, respiratory, thermoregulatory and metabolic parameters, which in turn, may have implications on exercise physiology and soccer performance. Therefore, the main aim of the present study was to investigate potential effects of menstrual cycle phase on performance in soccer specific tests.
Nine sub elite female soccer players, all of whom have menstrual cycles of physiological length; performed a series of physical performance tests (Yo-Yo Intermittent endurance test (Yo-Yo IET), counter movement jump (CMJ) and 3x30 m sprints). These were conducted at distinct time points during two main phases of the menstrual cycle (early follicular phase (FP) and mid luteal phase (LP)) where hormones contrasted at their greatest magnitude.
The professionalism and interest in female soccer has rapidly increased over the last decade, which has led to an expediential rise in research within many realms of the game. Despite the increasing amount of scientific work surrounding female soccer, gender-specific aspects of physiology, particularly the menstrual cycle and its effects on the physical performance, has been unaccounted for and remains fundamentally unknown[1, 2]. The menstrual cycle encompasses two main phases, the follicular phase (FP) and the luteal phase (LP). The follicular phase can split further into two sub phases; the early FP, which is characterised with low concentrations of both the key hormones oestrogen and progesterone; and the mid FP where oestrogen is high independently from progesterone. The LP is typified by high concentrations of both oestrogen and progesterone. These two main phases are separated by a steep surge in luteinizing hormone triggering ovulation. These cyclical changes are said to be often predictable whilst spanning over the reproductive years.
The current study aims to determine whether menstrual cycle phase influences a series of soccer related physical performance parameters in a high levelled soccer specific population. Based on the above considerations, the designs involve a strict protocol for the assessment of physiological cycles and distinct timing of performed tests in relation to cycle phases.
The participants body mass and sum of four skin folds were not significantly different between menstrual phases (Table 1). Oestrogen and progesterone levels of the players were significantly higher in the mid LP compared to the early FP.
In Yo-Yo IET performance, MBI intimated the qualitative inference that there was a possibly harmful effect for maximal performance in the LP, whereas, all other performance variables were found to be unclear. Moreover, the ES for the Yo-Yo IET was small to moderate, whereas all other variables were trivial (Table 2). For all performance variables, there were no significant differences revealed, although a trend towards significance was observed in the Yo-Yo IET between phases (p = 0.07) (Fig 3).
There was a likely beneficial inference for HR pre values tending towards the early FP, whereas the HR post values were deemed unclear. RPE was also deemed unclear. Lactate values were inferred to be unclear pre-and 1 min post the Yo-Yo test. However, at 3 and 5 min post, the MBIs suggested that it was very likely harmful during the early FP, where lactate values were higher. The effect sizes for all variables ranged from trivial to moderate (Table 3). There were significant differences between phases for HR prior to exercise and lactate values at minutes 1 and 3 post Yo-Yo test (p = 0.04, p = 0.01 and p = 0.03, respectively). For HR post, lactate pre-and lactate 1 min post Yo-Yo test and RPE there were no significant differences observed (p > 0.05).
The purpose of the study was to investigate whether menstrual cycle phase influences different facets of physical performance in a group of high level soccer players. The main finding of the study suggested that Yo-Yo IET performance was affected during the LP of the menstrual cycle. However, in all other aspect of measured performance were not different between phases.
To the authors knowledge this is the first study to investigate the effects of menstrual cycle phase on different sport specific physical parameters in female soccer players. In the nine players, menstrual cycle phase appeared to have an effect on maximal endurance capabilities, as demonstrated through the Yo-Yo IET. It has been suggested that physical performance in elite female soccer is highly related to their trained status and maximal capacities, therefore, it may be postulated that the maintenance of these high levels throughout the entire cycle is important for success. In 78% of our population, a reduction of meters completed was observed in the mid LP (Fig 3). The results of the current study are in line with the extensive work of Lebrun et al. Lebrun and colleagues used a cohort of 16 trained athletes (age 27.6 3.8 y, height 167.9 5.3 cm, mass 59.6 6.7 kg, VO2max 53.7 0.9 ml.kg-1.min-1), who participated in a variety of sports including running, cycling, triathlon, squash, cross-country skiing, ultimate frisbee and rowing. This study contained a strict phase confirmation comparable to our trial. Through the use of a progressive and continuous treadmill running test, the results indicated that maximal endurance capacity was reduced in the LP.
It is important to consider the specific type of sports to validly assess if and how menstrual cycle phase potentially affects physical performance. However, in soccer (which is intermittent in nature), there is a special challenge to evaluate sport-specific physical performance, this is due to the current difficulty to establish valid and reliable tests sensitive to the sport, unlike in endurance sports. The Yo-Yo IET has been suggested to replicate physical patterns in female soccer well, however, factors such as motivation have been suggested to cause differing results when being assessed at multiple time points, however, the exhaustion criteria was achieved in all players. In the present study, a reduction during the LP was observed in the clear majority of the players, with similar maximal HR, La and RPE values. Therefore, it can be postulated that although maximal effort was elicited in both phases, there was an observed reduction in maximal performance during the LP.
The menstrual cycle has been suggested to alter motor control and muscular strength. However, similarly to the present study de Jonge et al., found no differences between phases in 19 normally menstruating females for any strength parameter, including maximal isometric quadriceps strength with superimposed electrical stimulation, isokinetic knee flexion, and handgrip strength. It has been previously proposed that oestrogen, may have a strengthening action on skeletal muscle, although the mechanisms of this effect has not become clear. During the present study, the time points of measurements, were at minimal oestrogen (early FP) and when both progesterone and oestrogen were elevated (mid LP). Therefore, it can be speculated that the levels of oestrogen were not elevated enough to cause such an effect during early FP. Moreover, the antagonistic effect of progesterone, may have restricted the effects of oestrogen on muscular strength during LP. Altogether, the current results suggest that CMJ was not effected by cycle phase, however, due to the assumptions of the effect of oestrogen on strength, future investigations should target other time points within the menstrual cycle, where oestrogen is independently elevated, i.e. in the rise prior to ovulation.
The current study indicates that there is potentially a reduction in maximal endurance performance during the LP of the menstrual cycle. However, this reduction in performance was not observed for jumping and sprint performance. Therefore, due to the findings of the current study, practitioners should keep menstrual cycle phase constant when completing routine physical assessments with their players, to ensure that changes in performance are consistent with the outcome and not due to the effects of the menstrual cycle. Alternatively, the cycle phase should at least be recorded and taken into account when interpreting the results.
Previously, many different types of NTS barosensitive neurons were identified. However, the time course of NTS barosensitive neuronal activity (NA) in response to arterial pressure (AP) changes, and the relationship of NA-AP changes, have not yet been fully quantified. In this study, we made extracellular recordings of single NTS neurons firing in response to AP elevation induced by occlusion of the descending aorta in anesthetized rats. Our findings were that: 1) Thirty-five neurons (from 46 neurons) increased firing, whereas others neurons either decreased firing upon AP elevation, or were biphasic: first decreased firing upon AP elevation and then increased firing during AP decrease. 2) Fourteen neurons with excitatory responses were activated and rapidly increased their firing during the early phase of AP increase (early neurons); whereas 21 neurons did not increase firing until the mean arterial pressure changes (ΔMAP) reached near/after the peak (late neurons). 3) The early neurons had a significantly higher firing rate than late neurons during AP elevation at a similar rate. 4) Early neuron NA-ΔMAP relationship could be well fitted and characterized by the sigmoid logistic function with the maximal gain of 29.3. 5) The increase of early NA correlated linearly with the initial heart rate (HR) reduction. 6) The late neurons did not contribute to the initial HR reduction. However, the late NA could be well correlated with HR reduction during the late phase. Altogether, our study demonstrated that the NTS excitatory neurons could be grouped into early and late neurons based on their firing patterns. The early neurons could be characterized by the sigmoid logistic function, and different neurons may differently contribute to HR regulation. Importantly, the grouping and quantitative methods used in this study may provide a useful tool for future assessment of functional changes of early and late neurons in disease models. 041b061a72