Training with Rhythm: Female Physiology and Triathlon Performance (Part 1)

This is Part 1 of a two-part series on women’s triathlon training. In this part, I cover the principles, myths, and physiology. In Part 2, I'll move onto the practical side: pacing, strength, fuelling, and recovery.

Triathlon training advice often comes packed with buzzwords and niche theories, especially when it comes to female athletes. From “hacking” your menstrual cycle to the latest diet fad, it’s easy to get lost in overhyped strategies. But effective training for women isn’t about magic tricks, it’s about understanding the body’s rhythms and sticking to fundamentals. The focus of this article is on practical, real-world coaching: maintaining a steady training rhythm, building consistency, and making smart adjustments for strength, fuelling, pacing, and rest. Throughout, I’ll bust common myths and highlight that while women are physiologically different from men, they don’t need an entirely separate playbook, just a tailored approach that leverages consistency and communication. Let’s dive in.

Common Misconceptions about “Female-Specific” Training

Despite increasing awareness of women’s sports science, a number of myths still permeate triathlon training. It’s important to confront these misconceptions before drilling into specifics:

Myth 1: Women must train completely differently from men

A pervasive but oversimplified idea is that female athletes need a wholly distinct training program. In reality, the core principles of endurance training (progressive overload, recovery, and consistency) apply to everyone. Women are not “small men”, but that doesn’t mean ripping up the entire training rulebook. The fundamentals (aerobic development, skill practice, gradual intensification) remain the same; what changes are the nuances in application. For example, both male and female triathletes need long aerobic rides, interval work, and technique drills. The difference is that a woman might tweak timing or recovery based on her cycle or life stage. The biggest mistake is thinking female athletes are so different that basic training tenets don’t apply, they do.

Myth 2: Women can’t perform well during their period

For decades, female athletes were warned that menstruation would wreck their performance. Many still assume that if race day falls during their period, it’s game over. In truth, a woman’s cycle does not automatically derail performance. In fact, once menstruation begins (the low-hormone phase of the cycle), performance potential and pain tolerance can increase. While some athletes experience cramps or fatigue in the first day or two, others feel no ill effects or even a sense of relief and focus. Studies have found that objectively measured performance changes very little across the menstrual cycle, even if women perceive they have low days in their cycle. The real lesson: don’t assume you’re destined to underperform on your period, many women have set personal bests at this time. Every athlete is individual, so plan for comfort (e.g. managing cramps or ensuring iron levels are good), but don’t write off hard efforts solely due to your period.

Myth 3: “Cycle syncing” your training yields huge gains

Off the back of popular books and social media advice, some athletes try to micromanage every workout around menstrual cycle phases. While it’s true that hormonal fluctuations can cause subtle shifts (for instance, higher progesterone in the luteal phase can raise your core temperature and affect hydration and perceived exertion), the idea that you must schedule all hard intervals in one phase and all endurance in another is overhyped. The science is still young and often inconsistent on precise performance changes across the cycle. Over-focussing on cycle-based hacks can lead to complexity that overshadows consistency. What matters more is maintaining a training rhythm week in and week out, rather than chasing an “optimal” formula for each hormone spike. In practise, smart coaches may adjust a little, for example, if an athlete consistently feels flat right before her period, that might be a good time for a lighter recovery week. But they won’t throw out the entire plan or skip key workouts every month without clear evidence it’s needed. The bottom line: listen to your body’s cues, but don’t let a calendar app dictate your dedication.

Myth 4: Menopause means it’s time to slow down (or stop improving).

Yes, hormonal shifts around midlife bring challenges, muscle mass declines, recovery can be slower, but they do not slam the door on performance. In fact, with adjusted training, women in their 50s, 60s, and beyond are achieving remarkable results. Older women can continue to set personal bests or even out-compete younger athletes in endurance events. The misconception that “after 50 it’s all downhill” is outdated. Many postmenopausal triathletes are excelling, not by doing less, but by training smart. As I’ll explore, emphasising strength, intensity (yes, high-intensity work has big benefits for masters women), and recovery can keep performance high. The biggest limiter is often mindset: believing you’re “too old” can become a self-fulfilling prophecy. With the right approach, athletes can find their best form at any age.

Myth 5: Female athletes are frail or injury-prone due to hormones

Another misleading idea is that women can’t handle high training loads or tough sessions because of things like period-related injury risk or hormonal “fragility.” It’s true that oestrogen and progesterone influence tissues (for example, there’s discussion around oestrogen potentially increasing ligament laxity), but labelling female athletes as fundamentally fragile is inaccurate and harmful. Women are extremely resilient and are built for endurance. In fact, women tend to have a higher proportion of fatigue-resistant type I muscle fibres and excel in ultra-endurance contexts. They also recover well from steady-state training and can handle volume when built up appropriately. Rather than inherent fragility, what’s key is smart training structure and addressing known risk factors (like ensuring energy availability to prevent hormonal disturbances/RED-S, and strength training to protect joints and bones). Female athletes are not ticking time-bombs, with sound coaching they can train just as hard as men, and in some cases, out-adapt them in aerobic conditioning. Don’t let “fragility” myths justify holding back on robust training.

By dispelling these misconceptions, we set the stage for an approach that treats female athletes as capable endurance performers who benefit from both evidence-based tweaks and the timeless basics of training. Now, let’s look at what actually differentiates female physiology, and what doesn’t.

What Changes – and What Doesn’t – in Female Physiology

To train effectively, it helps to understand the genuine physiological differences women experience, both compared to men and across their own lifespan. Equally important is recognising what doesn’t change: the consistent principles that underpin performance. Here’s a clear-eyed look at female physiology through an endurance sports lens:

Biological differences (vs. males) that matter: From puberty onward, females and males diverge in key areas. Adult women have far lower testosterone levels than men, on the order of 15–20 times less. This contributes to differences in muscle mass and strength: on average men carry about 12 kg more skeletal muscle, with women exhibiting ~33% lower lower-body strength and ~40% lower upper-body strength. Women also tend to have a smaller aerobic engine in absolute terms: roughly VO₂max values ~75% of male counterparts on average (mostly due to body size, lung capacity, and haemoglobin differences). Male muscle fibres often have a higher capacity for anaerobic metabolism and explosive power, whereas female muscle tends to favour fat oxidation and endurance activity. These facts explain why elite men generally clock faster times and higher watts than elite women in triathlon.

However, what doesn’t change is the pathway to improvement. A female athlete builds aerobic capacity, strength, and speed through the same mechanisms as a male athlete: stress, recovery, adaptation. Muscles strengthen by repetitive load; cardiovascular fitness grows via accumulated volume and intensity; neuromuscular skill improves with practice. The female body is an adaptation machine just like the male body. Training is still applied biology over time: apply stress, allow recovery, and the body (male or female) will super-compensate to become fitter. In short, women and men respond to training more similarly than differently. The differences lie in scale and possibly in some optimal dosing, but not in the fundamental need to do the work.

Hormonal cycles and fluctuations: Within a woman’s own timeline, hormones introduce a moving target. During the reproductive years, oestrogen and progesterone levels rise and fall each month. Oestrogen peaks around ovulation (mid-cycle) and again (moderately) in the mid-luteal phase, while progesterone surges in the luteal phase after ovulation. These hormones affect everything from metabolism to fluid balance to joint laxity. For example, high progesterone elevates body temperature slightly and can increase breathing rate, which might make a hot summer run feel tougher in the luteal phase. High oestrogen can reduce the body’s ability to access quick carbohydrate stores, nudging metabolism toward fat use. This means during high-oestrogen times you might feel like you “hit the wall” sooner if not properly fuelled. Oestrogen also has beneficial effects: it’s anti-inflammatory and aids muscle repair, partly why some research suggests women recover well from endurance sessions. So across a month, a woman’s physiology isn’t static: it ebbs and flows.

Yet importantly, the core training capacity remains. A well-trained female athlete can hit hard intervals in any phase of her cycle; she might just need to adjust details like nutrition or expect a different RPE. Objective studies show no clear-cut performance loss in strength or aerobic tests tied directly to cycle phase, meaning if you test a woman’s 5K time or squat 1RM, you won’t consistently see it lowest in the luteal or highest in follicular across all women. Individual responses vary. So while hormones have some effect (especially on things like how she feels or what fuel she prefers), women do not become entirely “different athletes” week to week. What doesn’t change is the value of consistency: the female athletes who succeed aren’t those who perfectly time every session to their hormones, but those who train regularly through these normal fluctuations, making small tweaks as needed.

Life stages – puberty, pregnancy, menopause: Over a lifetime, female physiology undergoes major shifts. Puberty brings a surge of oestrogen, development of hips and breast tissue, and often an increase in body fat percentage. Young female athletes may notice changes in their balance or running economy as their bodies mature, but with good training they come out faster and stronger once adapted to the adult physique. Pregnancy is another extreme, though beyond our scope here, it’s worth noting many women maintain significant training during pregnancy and return to competition impressively post-childbirth, indicating the robustness of the female body.

The big one for long-term athletes is menopause, the end of menstrual cycles, typically around age 50. In perimenopause (the years leading up to menopause), hormone levels become erratic (oestrogen might swing high then crash low) and cycles become irregular. Women experience symptoms like hot flashes, night sweats, mood changes, and poor sleep as the ovaries wind down oestrogen production. Once menopause occurs (defined as 12 months without a period) and the transition completes, the body settles into a low-oestrogen, low-progesterone steady state (postmenopause). These changes have real impacts: bone density drops (women can lose 1–2% bone mass per year in early postmenopause), muscle mass declines more rapidly (sarcopenia risk increases), and recovery can feel slower. There are also metabolic shifts, some women become more insulin resistant, meaning they don’t tolerate high-glycaemic carbs as well. So yes, the playbook at 55 is not identical to the playbook at 25.

But again, what doesn’t change is the ability to adapt. Research and coaching experience show that even postmenopausal women improve aerobic fitness, build muscle, and get faster with appropriate training. The human body retains its responsiveness to exercise stimuli well into older age. Muscles will get stronger if you stress them (even if you have to work harder for it), and the heart and lungs will increase capacity with endurance work. In fact, exercise becomes more crucial as we age to counteract the hormone losses. The physiology changes, but the trainability remains.

In summary, female physiology brings its own rhythms that influence training details. Women aren’t just smaller men; for instance, they might rely more on fat for fuel, have different hydration needs, and face menopause-related shifts. Yet the unchanging backbone is that endurance performance is built through rhythmic, repeated training and recovery cycles for everyone. Female athletes thrive when we respect both the differences and the enduring universals of training. This philosophy of “different but not that different” underpins the rest of our discussion.

Rhythm Over Perfection: Training Through the Cycle and Menopause

One of the core ideas I emphasise is training with rhythm. What does that mean? In coaching terms, rhythm refers to establishing a sustainable, repeating pattern of training that the body can adapt to. It’s the opposite of a scattershot or highly erratic approach. For female athletes, leaning into a rhythm is often more productive than trying to time every session to an ever-changing hormonal landscape. Let’s explore how maintaining a rhythm, and making gradual adaptations, works across menstrual cycles and into peri-/postmenopause.

Embrace consistency through the menstrual cycle. Rather than viewing the menstrual cycle as a minefield requiring constant course-corrections, successful athletes treat it as just another training variable. The key is to maintain your weekly and monthly training structure (your rhythm), while adapting on the margins based on how you feel. You may shuffle your days around based on how you feel from moment to moment, but you still do the hard work that week, you don’t skip it entirely unless your body truly needs the rest.

This approach acknowledges the cycle without becoming a slave to it. It’s supported by evidence: many women report feeling a bit sluggish in the pre-menstrual late luteal phase, so planning lighter training just before your period can make sense. Conversely, the follicular phase (especially the week or so after your period starts) is often a time of higher energy and motivation, a great time to attack key sessions. One athlete might find she hits her best track workouts around Day 5-10 of her cycle; another might feel fantastic right after ovulation. Learning your personal pattern is valuable, but it comes through tracking and experience, not generic rules. Some coaches encourage female athletes to track cycle days alongside training logs. Over months you might see, for instance, a trend of higher perceived effort in the heat during luteal phases (due to that higher core temp and altered sweating). With that insight, you could adjust by cooling strategies or scheduling key heat sessions in lower-hormone weeks. The adjustments, however, are tweaks on a consistent backbone.

What we avoid is completely erratic training, e.g. doing no intensity for two weeks because it’s luteal phase, then trying to cram all hard sessions into the follicular phase. That undermines rhythmic adaptation. Remember, adaptation is cyclical and cumulative, not random and disjointed. A well-designed training plan already has its own cycle of stress and recovery (microcycles, mesocycles, etc.), which can often be overlaid on the menstrual cycle without much conflict. If something doesn’t line up (say a race falls in a “bad” phase), focus on controllables like extra fuelling or mindset rather than despairing about hormones. Many women surprise themselves racing on “off” days and realising performance was fine. The body craves repetition and routine, even a hormonally fluctuating body. By keeping a steady training rhythm, you allow your body to predict and prepare for the stresses, leading to better adaptation over time.

Adapting rhythm into perimenopause. Perimenopause (typically late 40s, though it can start earlier) is when the menstrual rhythm itself starts breaking down. Cycles become irregular. You might skip a month, then have a very heavy period, then go two months without, etc. Hormone levels swing unpredictably. This can be frustrating for planning, because the “known pattern” an athlete used to rely on (like knowing week 3 of her cycle is her strong week) might vanish. The strategy here is to double down on general rhythm and be flexible on the daily adjustments. If you wake up feeling crushed (maybe a bad night of sleep from hot flashes), you swap that day’s hard workout to later in the week if possible. If you feel unexpectedly great, take advantage and push a bit. It’s a dance of sticking to the big-picture routine while improvising day to day.

Perimenopause is essentially an exercise in auto-regulation: since the internal hormonal rhythm is chaotic, you create an external training rhythm (weekly routine) but allow for auto-regulation within it. Women who stay active through this phase often come out the other side (postmenopause) with a very refined sense of their body and still retaining strong fitness.

Postmenopause and new steady-state rhythm. Once menopause is complete and you’re in the postmenopausal stage, one big variable is gone: no more menstrual cycles. Many women actually find this liberating for training: no more surprise periods or hormonal rollercoasters; you can settle into a consistent pattern without monthly disruption. That said, the “new normal” includes chronically low oestrogen/progesterone, which has its own effects (I’ve mentioned sleep issues, joint stiffness, slower recovery). Here, establishing a sustainable rhythm is crucial in a different way: you might find you need a longer recovery arc after hard blocks. For instance, a postmenopausal athlete may respond well to a pattern of 2 days hard, 1 day easy, or a 10-day microcycle instead of a 7-day week (because research suggests 72 hours between hard sessions might be ideal to fully recover at this stage). Some master athletes thrive on a “3 weeks on, 1 week off” mesocycle, where every fourth week is very light, allowing bones, tendons, and muscles extra time to regenerate. That becomes their training rhythm.

Consistency is just as important at 55 as at 25, perhaps more so. Regular exercise essentially becomes medicine to counteract ageing effects. A consistent rhythm of strength training and impact exercise can slow bone loss. Routine high-intensity sessions (with enough recovery) keep VO₂max from plummeting and help manage body composition. Perhaps counterintuitively, intensity and load cannot disappear from the schedule, they just need more spacing and care. Many coaches of older athletes focus on a weekly rhythm that alternates stress days and recovery days more strictly. For example: Tuesday big intensity, Wednesday recovery swim or yoga, Thursday moderate bike, Friday off, Saturday long aerobic, Sunday off/easy, Monday moderate run… and repeat. The repetition and spacing help the athlete know what to expect and how to prepare (e.g. mentally and nutrition-wise for the hard days). Habits trump motivation at this stage, when life and fatigue can easily distract, having a ingrained schedule keeps you on track.

Across all these phases, the guiding philosophy is to respect the body’s signals without being paralysed by them. Training with rhythm means you’re not overreacting to every little blip. You expect some ups and downs and see them as part of the cycle. As one of my coaching mantras goes, “triathlon success is built on a foundation of consistent, purposeful repetition”. That holds true whether you’re dealing with monthly hormone swings or decade-long ageing changes. By embracing the process (even the boring bits and tough days) instead of seeking constant novelty or perfection, female athletes can build a huge aerobic base and robust fitness that carries them through any physiological storms.

Next week, we’ll get into the nitty-gritty of how to adjust key training elements, pacing, strength work, nutrition, and recovery, in practical terms.

If you want a coach who builds training around your rhythm, not a spreadsheet, look at my coaching services.

Prefer to self-guide? My training plans use the same progressive rhythm I coach with. Whichever path you choose, build strength where it matters, train with purpose, and you’ll race with confidence.