Understanding the Menstrual Cycle and Blood Lactate: Does It Really Matter?

This blog took a little longer to compile than my previous one—and for good reason. The volume of data available on this topic is growing rapidly, and with it comes a need to carefully sift through both historic and emerging research.

One question sits at the centre of it all: does the menstrual cycle influence blood lactate levels during training?

Data collected from athletes who work with Blake Performance Lab has shown that there are lactate level fluctuations over the course of their menstrual cycle, and this data has been valuable in developing athletic performance and recovery. Read on for more.

Effect vs No Effect: What Does the Research Say?

Current literature presents a divided picture. Some recent studies have dismissed any meaningful relationship between menstrual cycle phases and blood lactate responses during exercise. However, this is only one side of the conversation.

A growing body of research—building on earlier pioneering work from the 1980s and 1990s—suggests otherwise. These studies indicate that hormonal fluctuations across the menstrual cycle do influence physiological responses in female athletes, including measurable changes in blood lactate levels.

From a physiological standpoint, this makes sense. Hormones are powerful regulators of metabolism, energy utilisation, and recovery. To assume they have no impact on performance would overlook their fundamental role in the body.

Supporting this, a 2022 study of 195 Australian athletes preparing for the Tokyo Olympics found that:

• 65.6% reported their menstrual cycle affected training

• 58% reported effects during competition

While it’s easy to question the relevance of elite athletes to the general population, there’s an important nuance here. Elite performers are often highly attuned to their bodies. With fewer external stressors and distractions, they may simply be more aware of subtle physiological changes that others experience but don’t consciously register.

In contrast, everyday cognitive load—work, study, life stress—can reduce awareness, leading to what’s known as inattentional blindness: missing what is happening right in front of us.

What Does This Mean for the Individual?

So, the key question: does the menstrual cycle affect everyone in the same way?

In short—no.

Responses vary widely between individuals, just as cycles themselves differ in length, symptoms, and associated health factors. This variability reinforces the need for an individualised approach rather than a one-size-fits-all model.

Awareness and tracking become essential tools here. By understanding the phases of the menstrual cycle and consistently monitoring personal patterns, athletes can better anticipate how their body will respond to training.

A Practical Example

Many will recognise this scenario:

You’re in the week leading up to your period. A training session—perhaps a threshold effort—feels unusually difficult. Power output drops, and despite your effort, you can’t replicate previous performances.

Then comes the turning point: you take on quick sugars—gels, sports drinks, even sweets—and suddenly things improve.

Why?

During this phase, hormonal changes can signal the body to conserve glucose in the liver, preparing for a potential pregnancy. This can limit readily available energy during exercise, making external carbohydrate intake more important.

The solution isn’t to push harder—it’s to plan smarter. Understanding why this happens allows for targeted fuelling strategies that support performance rather than fighting against physiology.

From Awareness to Strategy

At Blake Performance Lab, this understanding is applied through long-term planning and individualised athlete support.

The current approach is built on three key principles:

1. Understand the individual Each athlete’s response to different phases of their cycle is unique and must be observed over time.

2. Track and plan ahead By mapping cycles against competition schedules, it becomes possible to anticipate challenges and prepare accordingly.

3. Monitor and adapt Tracking lactate responses across the cycle allows for adjustments in both training intensity and nutritional strategy to optimise performance.

The standard protocol begins with a lactate test to establish individual training zones for a given training block. At Blake Performance Lab, these zones are prescribed as ranges rather than fixed values, allowing for day-to-day variability driven by factors such as sleep, stress, fatigue, and natural physiological fluctuations.

Working within a defined zone range ensures the athlete remains within the intended training stimulus, providing both structure and flexibility to maintain training quality despite normal variations in readiness.

A key addition to the above process is the use of a lactate test to establish accurate training zones, followed by targeted lactate monitoring across one or two training sessions at different points in the menstrual cycle. This approach helps capture individual lactate fluctuations, providing athletes with clear, personalised insight into how their physiology responds throughout the cycle. 

This not only improves the precision of training prescription but also plays an important role in education—empowering female athletes to better understand their bodies and make informed decisions around training, fuelling, and recovery.

The Value of Consistency

Refinement comes through repetition. By consistently applying and rehearsing these strategies each month, athletes develop confidence in their approach.

Over time, this leads to a deeper understanding of their own physiology—allowing them to adapt training intelligently, rather than reactively.

Ultimately, it’s not just about whether the menstrual cycle affects performance. It’s about recognising that, for many, it does—and using that knowledge as a tool to train smarter, fuel better, and perform at a higher level.

Want to know more? Email info@blakeperformancelab.com