INSPO Fitness Journal May 2019

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HORMONES, PERFORMANCE AND TRAINING BY ALISON STOREY The menstrual cycle can affect energy availability, readiness to train and factors of physical performance for female exercisers. Utilising the menstrual cycle to prescribe training and recovery may better optimise training for performance. Common practice among trainers and coaches is to create training programs and plans that ensure adequate recovery between training sessions, and a mix of sessions that create a progressive improvement in performance. While this measured and progressive overload, compensation and recovery plan may work on paper, the effect of a female athlete’s menstrual cycle may vastly affect the result, and this begs the question that if a measure of hormonal cycles was included in that planning, whether the end result of all that hard work and training would be enhanced. Despite a level of interest in the effect of the menstrual cycle on athletic performance and strength, there remains considerable debate in the literature, a limited amount of research with elite female athletes, and even less with mature and generally exercising women. Several studies have shown a fluctuation in strength, peak power and V02 max across the phases of the menstrual cycle, while others show elevated heart rate response to the same task at different times in the cycle. Controversially, yet other studies show no effect of the different phases of the menstrual cycle on performance. The ‘easy’ and commonly used solution is to prescribe oral contraceptives (OC) to ‘dull’ the hormone response. In the early 1980s several studies showed that only 5 to 12 percent of athletic women were using an oral contraceptive, whereas more recently, an unpublished survey of 68 athletes from 15 different sports reported 83 percent of athletes taking an oral contraceptive. Interestingly though, some studies have suggested that OC use can decrease VO2 by 5-15 percent and anaerobic power to vary measurably over the course of an OC cycle in trained athletes. Despite the widespread use of oral contraceptive (OC) medications among athletes, few researchers have examined the effect of the OC on athletic performance, and this lack of research compounds the mostly inconclusive findings of any existing literature on the menstrual cycle and athletic performance. PHYSIOLOGY OF THE MENSTRUAL CYCLE The length of the menstrual cycle can vary ranging from 25 to 38 days, however 28 days is considered as the average span and it can be divided into three biological phases based on oestrogen, progesterone and with less relevance, testosterone. 1. The Follicular phase, days 5-13 (low oestrogen, low progesterone) 2. The Ovulation phase, around day 14 (high 10 INSPO – FITNESS JOURNAL MAY 2019
day 21, with the authors of the study stating that “in fact, there is evidence that maximum force development is enhanced when strength training is conducted in the follicular phase, relative to luteal- phase training”. Twenty untrained women were put through leg press strength tests over the course of several months in a 2014 study which concluded that follicular based training showed a higher gain in muscle strength than luteal training and as a result, recommended that “females not on OC should base the periodization of their strength training on their individual menstrual cycle”. Maximal voluntary isometric strength (MVC) of the quadriceps and grip strength of 20 untrained women was used in a 2006 study. MVC was highest for both quadriceps and grip strength around the time of ovulation (day 12-18) by as much as 11 percent. oestrogen, higher testosterone, lower progesterone) 3. Luteal phase, days 15-28 (high oestrogen, high progesterone) which is followed by menstruation Empirical evidence would suggest these hormonal changes result in different levels of motivation and performance across the cycle. ENDURANCE CAPACITY Vaiksaar et al completed a study in 2011 with rowers on oral contraception (OC) that used a one hour rowing ergometer test to gauge any difference in power output, heart rate or Vo2 over two phases of the OC cycle. They concluded there was no change in aerobic endurance capacity, however did observe a higher ventilatory response during the luteal phase. Conversely, a review by Rechichi et al (2009) found a 5-15 percent reduction in Vo2max in active women on OC, while a randomised cross-over trial with ten female runners found a decreased Vo2 max of between 3 and 5.8 percent when on OC medication. The effect of OC use on endurance capacity was looked into with 14 well trained athletes (Vo2 >50ml/kg/min) in 2003. It is understood to be the only randomised, double blind, placebo-controlled trial of the effects of oral contraceptive on athletic performance. Their findings suggest that while direct aerobic endurance measures were not significantly affected, absolute and relative changes in Vo2max decreased in the OC group by 4.7 percent, with the placebo group either maintaining or increasing (~1.5 percent) Vo2 max measures over the same time. Regular heavy losses of blood with menstruation may also affect an athlete’s oxygen carrying capacity and can lead to anaemia, both of which can negatively affect the endurance capability of any athlete. Fluctuations in endurance performance during the phases of the menstrual cycle are also thought to be related to variances in heat regulation and metabolism. When considered alongside evidence that training or racing in hot conditions can elevate body temperature and heart rate, the timing of these may become even more relevant to female performance. ANAEROBIC POWER Redman & Weatherby (2004) undertook testing with five elite female rowers that were taking a low dose OC pill, in repeating both a 10 sec all-out effort and a 1000m maximal effort on the rowing ergometer, at two different points in the menstrual cycle and over three complete cycles. These points paralleled the change from high oestrogen and high progestogen (day 16-18) to low oestrogen and low progestogen (day 26-28). Both peak power output was greater and 1000m time faster (by as much as 2.5secs), in the menses phase, days 26-28. A study with soccer players published in 2017 found Yo-Yo intermittent test scores were lower during the mid-luteal phase than the early follicular phase for over 78 percent of the tested subjects. The authors concluded there is a drop in maximal endurance capacity in the mid luteal phase and recommend this be considered when monitoring athlete performance. STRENGTH The highest levels of strength in athletes involved in a 2018 study were measured at day 14 (ovulation) and were at their lowest at Finally, a study with 10 team sport athletes (OC users) exploring the effect of the menstrual cycle on team sport performance was undertaken by Rechichi & Dawson in 2007. Results of a 45 cm drop height jump test were higher between days 13 and 17 (around ovulation) when compared with approx. day 24 and day 27. In reviewing studies, there appears little argument that strong complexities are involved in the hormonal response to exercise across the menstrual cycle for any level of exercising female. It does however appear that peak power may be higher during the follicular and ovulation phases, whilst strength training may have a greater effect when completed during the follicular phase rather than the luteal phase. Maximal endurance performance may be reduced during the luteal phase, and conversely at its most effective during the follicular phase. Heart rate pre-exercise and lactate levels post exercise have been found to be significantly higher in the luteal phase, along with an associated increase in body temperature which has been suggested to reduce endurance capacity and increase cardiovascular strain. While further research into the effects of the menstrual cycle on exercise performance are needed, it is hard to ignore these findings, or that OC use may be detrimental to both endurance capacity and strength. If the menstrual cycle has a physiological effect on performance, both positive and negative, it seems essential to research this area more thoroughly if ultimate athletic female performance is a goal for the 21 century, and to maybe adjust the paradigm of just training women like small men. ALISON STOREY is a personal trainer who has represented New Zealand in three different sports (beach volleyball, rowing and rhythmic gymnastics). She has been awarded New Zealand Personal Trainer of the Year twice and runs Storey Sport, a mobile personal and sports training business which provides a range of services that optimise the fitness and wellbeing of its clients. storeysport.co.nz INSPO – FITNESS JOURNAL MAY 2019 11
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