063: Menstrual Cycle Phases Do Not Influence the Effectiveness of Stretching in Healthy WomenJul 19, 2022
Michalik, P., Michalski, T., Witkowski, J., et al. (2022.) 'The Influence of Menstrual Cycle on the Efficiency of Stretching.' Advances in Clinical and Experimental Medicine volume 31, number 4, pages 381-387.
48 females (21-24 years old) performed 3 x 45-second static passive hamstring stretches during the follicular (days 2-5), ovulatory (days 12-15), and luteal (days 16-28) phases of the menstrual cycle. Stretching caused hamstring flexibility to increase in each phase of the menstrual cycle but there were no statistically significant differences between them. Fluctuations in flexibility during the menstrual cycle may still be present because of hormonal influences on stretching adherence.
Flexibility improves following stretching regardless of sex, but females tend to display better responses compared to males. One possible explanation for sex-based differences in flexibility is that males have higher levels of passive stiffness and pain sensitivity than females (Marshall and Siegler, 2014). A potential mechanism at work is that numerous parameters within various body systems are affected by fluctuating reproductive hormones, and these endocrine-driven systemic changes have consequences on the physiology of the locomotor system (Barros and Gustafsson, 2011).
Fluctuating levels of reproductive hormones during the menstrual cycle may affect the physical properties of oestrogen and progesterone receptors in bones, skeletal muscles, ligaments, and nervous system structures. For example, fluctuations in oestrogen levels are associated with changing amounts of type I and III collagen, which is an essential structural protein found in connective tissues. In the periovulatory phase, type III collagen levels increase and type I levels decrease, leading to a higher tolerance to the mechanical loads imparted on tissues by stretching (Fede et al., 2019).
High-quality research examining the relationship between the different phases of the menstrual cycle and joint flexibility is scarce, and results from the previous research that does exist are frequently inconclusive, with authors reporting either no significant effect of the menstrual cycle on range of motion or that different muscle groups exhibit significantly contrasting levels of passive stiffness at various points throughout the cycle.
This was one of the first studies to examine the effects of stretching on hamstring flexibility over the course of a month that specifically defined the separate phases of the menstrual cycle based on historical reports of the participants. Although the validity of the findings could have been enhanced by testing serum hormonal levels, the results suggest that healthy young females do not need to consider specific phases of the menstrual cycle in the context of stretching effectiveness.
However, an important caveat to these recommendations is the psychobiological aspect of menstruation - namely that subjective perceptions of fatigue and mood may affect stretching adherence, which will affect range of motion.
Barros, R. & Gustafsson, J. (2011.) 'Estrogen Receptors and the Metabolic Network.' Cell Metabolism volume 14, number 3, pages 289-299.
Fede, C. et al. (2019.) 'Sensitivity of the Fasciae to Sex Hormone Levels: Modulation of Collagen-I, Collagen-III, and Fibrillin Production.' PLoS One volume 14, number 9, article e00223195.
Marshall, P. W. & Siegler, J. C. (2014.) 'Lower Hamstring Extensibility in Men Compared to Women is Explained by Differences in Stretch Tolerance.' BMC Musculoskeletal Disorders volume 15, number 1, article 223.