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The physiology of men and women have historically been pooled together when it comes to the prescription of training interventions. As Stacy Simms once said, “women are not small men.” However, the tide is changing, and quite rightly so.

Here’s why….

Hormones act as messengers, delivering bits of information from one part of the body (brain) to the other (organs). They inform us when to eat, sleep, grow etc – so much pretty much all that we do on a daily basis. They also have a vast impact on our appetite, readiness to train, mood…the list goes on. They’re kind of a big deal. Men and women are built very different in that respect. Men’s hormones are fairly constant with minor fluctuations in testosterone throughout the day, and a gradual decline in line with the aging process. On the other hand, women are a very different story – enter the menstrual cycle.

The menstrual cycle has four different phases, which is often broken down more broadly into just the follicular and luteal phases;

• Menstrual – onset of period whereby levels of oestrogen and progesterone drop. This phase typically lasts 3-7 days but can vary between individuals.
• Follicular - begins on day one of your period and continues until ovulation, and is normally divided into two sub-phases: the early follicular phase (EFP), which is characterized by concentrations of both oestrogen and progesterone; and (b) the late follicular phase (LFP) where maximal oestrogen concentration coincides with low progesterone levels and ends with an upsurge of luteinizing hormone that precedes the ovulation. This phase typically lasts a total of about 16 days.
• Ovulation - oestrogen levels begin to rise and reach a peak just prior to ovulation, whilst progesterone levels remain low. The typically happens around day 14 of your cycle.
• Luteal - this phase begins once the luteinizing hormone have returned to basal level. This is characterized by high concentrations of both oestrogen and progesterone, followed by a drop in both hormones and the restart of the cycle. The luteal phase is when PMS symptoms can be prevalent, like bloating, headache, weight changes, food cravings, and trouble sleeping. This phase typically lasts 11-17 days.

 

Aside from their reproductive roles, both oestrogen and progesterone have numerous physiological effects outside of the reproductive system. Oestrogen is known for its anabolic qualities, and can influence muscle strength, hypertrophy, protein synthesis, and therefore, plays a key role in muscle repair and regeneration.

In contrast, progesterone is thought to inhibit the effects of oestrogen, with some researchers even reporting a catabolic effect of progesterone. Given these potential effects that oestrogen and progesterone receptors have been found in skeletal muscle, variations in these sex hormones across the menstrual cycle might influence strength training outcomes in women.

Given these differences in hormone functions, it has been speculated that skeletal muscle performance might vary with alterations in hormone production during different phases of the menstrual cycle. Sarwar et al, (1996) reported an 11% increase in quadriceps and handgrip maximum voluntary isometric force in the ovulation period which coincided with the lower hormone phase. However, they do not provide information related to the association of force and velocity in submaximal loading.

In addition, a study of 20 active females found that women could make greater strength gains, and produce more when force when they strength trained during their low hormone phase in comparison to high hormone. Muscle soreness and recoverability were also noted to be heightened during the lower hormone phase.

On the contrary, a study by Blanca Romero-Moraleda, et al, 2019, showed that resistance-trained eumenorrheic females have similar velocity, force, and power performance when exercising with loads equivalent to 20, 40, 60 and 80% of 1RM in the smith machine half-squat exercise during the different phases of the menstrual cycle.

So, during the lower hormone phase of the cycle (onset of menstruation), training may generally feel easier. Although the research on performance during menstruation is scarce, some athletes have documented faster times during menstruation in comparison to the premenstrual period. Force production capabilities may be hindered a little during the higher hormone phase, but key performance indicators such as VO2max and lactate threshold remain constant throughout your cycle. Several studies have noted that reaction time and. neuromuscular control can make the perceived effort on more dynamic tasks increase. Blood sugar levels, breathing rates and thermoregulation can be negatively impacted during this part of the cycle, which can account for decreases in aerobic output and strength.

Regardless of the literature, everyone is different. Some women may have regular cycles, some may be experiencing amenorrhea, or other menstrual disruptions, such as relative energy deficiency in sport (RED-S). Some women may suffer from PMS (premenstrual syndrome), and other menstrual related symptoms, such as dysmenorrhea more than others. Whatever the goal – open up the conversation and cater for the individual in front of you.

 

References

Bambaeichi E, Reilly T, Cable N, Giacomoni M. The Isolated and Combined Effects of Menstrual Cycle Phase and Time-of-Day on Muscle Strength of Eumenorrheic Females. Chronobiol Int, 2004; 21: 645–60

Blanca R-M, Juan DC, Jorge G-H, Carlos R_M, Jozo G, Beatriz L. The Influence of the Menstrual Cycle on Muscle Strength and Power Performance. Journal of Human Kinetics volume 68/2019, 123-133. DOI: 10.2478/hukin-2019-0061, 123; Strength & Power

Flanagan SD, Dunn-Lewis C, Comstock BA, Maresh CM, Volek JS, Denegar CR, and Kraemer WJ. Cortical Activity during a Highly-Trained Resistance Exercise Movement Emphasizing Force, Power or Volume. Brain Sci, 2012; 2: 649-66

Janse DJ. Effects of the Menstrual Cycle on Exercise Performance. Sports Medicine. 2003;33(11):833-851. doi:10.2165/00007256-200333110-00004

Knowles OE, Aisbett B, Main LC, Drinkwater EJ, Orellana L, & Lamon S. Resistance Training and Skeletal Muscle Protein Metabolism in Eumenorrheic Females: Implications for Researchers and Practitioners. Sports Medicine, 2019, 49(11), 1637-165

Sarwar R, Niclos B, Rutherford O. Changes in Muscle Strength, Relaxation Rate and Fatiguability During the Human Menstrual Cycle. J Physiol, 1996; 493: 267–272

Sims S. ROAR. How to Match your Food and Fitness to your Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life.

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