#588: Menstrual Cycle “Syncing”: Do the Claims Hold Up to Evidence? – Expert Panel

Introduction to this Episode

How much do hormonal fluctuations really influence performance and recovery? Should women be adjusting their training and nutrition based on the menstrual cycle? And do female athletes need different protein strategies or recovery protocols than men?

These are questions that have fuelled countless online claims, from rigid “cycle syncing” programmes to supposedly gender-specific nutrition rules. But how much of that is actually grounded in evidence?

In this episode, the conversation tackles those debates head-on, exploring what we truly know about female physiology, adaptation, and recovery, and where confident narratives outpace the science.

Youʼll hear from four leading experts: Professors Kirsty Elliot-Sale, Stu Phillips, Shona Halson, and Dr. Eric Helms, as they unpack the data on menstrual-cycle variation, autoregulation, and the real determinants of muscle growth and recovery in women.

These discussions were originally recorded live as part of “The Inside Advantage” event hosted by Optimum Nutrition at the McLaren F1 Performance Centre in the UK, where Danny Lennon moderated the session.

Guests in this Episode

Prof. Stu Phillips is Professor of Kinesiology in Skeletal Muscle Health at McMaster University. His research is focused on human skeletal muscle protein turnover.

Prof. Kirsty Elliott-Sale is Professor of Female Endocrinology and Exercise Physiology at Manchester Metropolitan University (UK). Her research focuses on female athlete physiology, musculoskeletal health and relative energy deficiency in sport (RED-S).

Prof. Shona Halson (ACU) was the Head Recovery Physiologist at the Australian Institute of Sport from 2002 to 2018. Her research focuses on recovery, fatigue and sleep in elite athletes.

Eric Helms, PhD is an AUT Senior Research Fellow at SPRINZ at Auckland University of Technology. Eric researches physique and strength sport, specifically training and nutrition, with an emphasis on long-term sport careers holistically integrated with life.

Useful Terminology for this Episode

• Menstrual Cycle Phases: The two main phases of the menstrual cycle.
  • The follicular phase begins on the first day of menstruation and lasts until ovulation, characterized by rising estrogen and relatively low progesterone.
  • The luteal phase follows ovulation, with high progesterone and moderate estrogen, and continues until the next menstrual period.
• Cycle Syncing: A strategy that attempts to align training (and sometimes nutrition) with specific menstrual cycle phases under the belief that hormonal changes create “best” or “worst” times for certain adaptations or performance. This concept is widely discussed but not strongly supported by scientific evidence.
• Autoregulation: A training approach that adjusts workout intensity, volume, or rest based on the athleteʼs real-time feedback and condition, rather than sticking rigidly to a pre-planned program.
• Hypertrophy: An increase in the size of muscle fibers, leading to muscle growth.
• Relative Energy Deficiency in Sport (RED-S): A syndrome caused by chronically low energy availability – meaning an athleteʼs dietary energy intake is insufficient to meet the combined demands of training and basic physiology.
• Rating of Perceived Exertion (RPE): A psychophysiological measure of exercise intensity in which an individual provides a conscious, subjective rating of how hard the effort feels, integrating signals from multiple physiological systems (cardiorespiratory strain, metabolic stress, neuromuscular load, thermoregulatory stress) and contextual factors (motivation, affect, environmental conditions).
• Nocebo Effect: An adverse outcome driven by negative expectations, where cognitive and affective processes (anticipation of pain, fear, anxiety, prior beliefs) trigger measurable neurobiological responses (such as increased activity in pain-facilitation pathways, altered autonomic output, or stress-hormone release) that produce real, perceivable symptoms.