Original article written by Salvador Vargas Molina, Jorge Luis Petro, Angel Ramon Romance Garcia and colleagues
Background
We know there’s a substantial discrepancy in the amount of research that looks solely at male vs female human cohorts in sport science. While I have my suspicions on some reasons why this occurs, one of the major reasons is due to researchers often just deeming projects that include female humans ‘too hard’. This is particularly prevalent in research which accounts for menstrual cycle phase. While I am not saying that this type of research is not difficult (or costly!), I do think that as sport scientists we should be pushing ourselves to do high quality work that helps push the field forward. Furthermore, as ~50% of the world’s human population is female, considering the influence of basic biological processes is important.
What the authors did
Across the menstrual cycle, there are fluctuations in ovarian hormones. These hormones have a range of roles in normal health and function. However, these fluctuations have been mooted to cause substantial alterations in performance and it has been suggested that by carefully planning training, you can influence training adaptations. Despite this often being stated, there’s a lack of evidence (in either direction) to support this contention. Consequently, when this paper by Vargas-Molina et al., [1] came across my desk, I sat up and took notice. I will acknowledge it’s rare for me to review a pilot study (i.e., a small-scale preliminary study) but the importance and impact of this work is something that is important for strength coaches (even if it is ‘just’ a pilot study). Considering this, in the study by Vargas-Molina et al., [1] the effects of periodising resistance training according to menstrual cycle phase were investigated. Specifically, changes in body composition, strength, and body composition were assessed.
What the authors found
Two different groups completed four training sessions per week for eight weeks using a weekly undulating model. One group had training prescribed according to each participant’s menstrual cycle phase (MC group), while the other group followed a relatively normal periodised model which did not account for menstrual cycle phase. ‘Strength’, ‘hypertrophy’, ‘muscular endurance’, and ‘recovery’ weeks were used to guide training, with repetition maximum zones prescribed. Changes in fat mass, fat free mass, squat, bench press, and countermovement jump performance were assessed pre- and post-intervention.
While it should be acknowledged early on that the statistical interpretation of this research is relatively limited as only five participants were used within each group (again, this is a pilot study), we are able to eyeball some of these numbers to get an idea about the changes that were occurring. Both groups seemed to have considerable improvements in fat free mass, bench press, and back squat strength. There was only a single between group difference, with the bench press improvements greater in the MC group. However, this should be taken with a pinch of salt as the MC group also had a substantially lower mean starting strength. Finally, while not significant, CMJ performance tended to be greater in the MC group (although, this group again had a lower baseline).
Limitations
I’m going to note again that this type of research is very difficult to do. Furthermore, because it’s acknowledged to be a pilot study, it’s important not to knock the small numbers. While the authors have done a nice job in helping shed light on this area and undoubtably more information will come in the future, there are some limitations to this study that need to be acknowledged.
First, while it’s excellent to see some form of hormonal verification going on with regards to assessing luteinising hormone in the urine, blood serum assessment is required to ensure that the females within the study have expected hormonal fluctuations and that the participants who were involved do not have anovulatory or luteal-deficient cycles.
Second, it’s not clear whether hormonal contraceptive use was allowed in the three months prior to recruitment. While it’s stated that hormonal contraceptive users were not included in the study, it’s not clear whether previous use had occurred and for how long. This is an important consideration as hormonal contraceptive use might increase the risk of atypical hormonal profiles (which wasn’t assessed due to only urine luteinising hormone being measured).
Third, the authors didn’t provide a clear rationale of why certain weeks of the menstrual cycle were aligned with training volumes and loads. While there is a small amount of justification for the recovery weeks, the other weeks in the training programme need a bit more information to fully elucidate the hormonal mechanisms that would support this order of training prescription.
Finally, and tying into the previous point, the actual training makes me scratch my head a little. For example, during the ‘recovery’ weeks, is three sets of 12-15 repetition maximum truly going to facilitate recovery? Furthermore, if there’s a need to justify recovery within a certain week of the training programme due to menstrual cycle related changes, is it appropriate to do what is arguably some of the hardest training sessions then? I know that I certainly wouldn’t be promoting that type of training if recovery is indeed required!!
What this means for coaches
For all the issues raised above, it should be acknowledged that while the information and understanding in this space is still growing, there are some nice little takeaways for the practitioner. First, it demonstrates that periodising training based off the menstrual cycle may be a feasible method of altering training volumes and loads. Additionally, while we’re still waiting for good strong evidence to support its use (more on this below), altering training volumes across the menstrual cycle may have a slight advantage. This space is still developing though and we must use caution when interpreting these findings.
Reviewer’s comment
The manipulation of training across the menstrual cycle is something that I think is incredibly exciting and interesting. We currently have very little understanding of how it can best be done or solid evidence to even prove it works. However, small studies like this help to continue pushing the field forward and lead to bigger projects in the future. I will note that the SPRINT Research Centre at Australian Catholic University is putting considerable effort into this S&C space and trying to understand whether programming training when certain hormones are high/low is favourable for adaptations. Specifically, one of my PhD students (Ms Gabriella Munteanu (@Gabbi_Munteanu)) is completing some world-class work investigating the effects of periodisation models and prescription methods throughout the menstrual cycle and assessing how it influences performance, recovery, and adaptation. Watch this space…!
Recommended resources
- Read – The effects of menstrual cycle phase on exercise performance in eumenorrheic women: A systematic review and meta-analysis – Kelly Lee McNulty and colleagues
- Read – Methodological recommendations for menstrual cycle research in sports and exercise – Xanne Janse de Jonge and colleagues