@NancyTree the latest research we have shows that men and women are totally different. Conventionally, coaches, trainers and some researchers have treated women as "weaker men". It is kinda true and it ain't. The female hormonal cycle ensures that women's hormonal profile changes every day while men's remains the same with a more or less predictable arc at the beginning of the day and dip in the end. The difference in the chemical cocktail experienced by women's bodies as opposed to men's adds a highly variable complexity that makes it, at the moment, hard to study. Experimenting on women, even when that experimentation is relatively benign and comes with consent, is problematic due to the fact that they may be pregnant or may get pregnant during the study, so most researchers use male subjects and then assume women are more or less the same.
With that beginning you know we are in now for a wild ride.
The study you reference above is correct. Different times of exercise and different types of exercise deliver different results in men and women. This was obviously always going to be the case. Hormones are the neurochemical messengers that prepare the body for action so their presence or lack of, depending on the phase of a woman's menstrual cycle and the time of day for a man, are going to determine to a large degree, how the body prepares for action and allocates resources to match it.
But there are complexities here too, not least the underlying question do the fluctuations in hormones negate some of the benefits of exercise for women? A 2023 analyses of studies to date concluded that when it comes to strength training the daily fluctuations of a woman't hormones were immaterial. That analysis can be found
here. Another analysis, carried out in 2023, and looking at results not just of resistance training but exercise in general, again found small differences in
exercise effectiveness. It then cited the poor quality of existing studies on women and the lack of many meaningful ones and suggested it cannot reach a conclusion with confidence.
So, now back to square one. Here's what we incontrovertibly know: women's menstrual cycle changes their hormonal profile every day. But the cycle itself has a fairly predictable ascending and descending curve of hormones. Here they
reference sex (as a behavior) but the same goes for exercise. The changes affect behavior (i.e. motivation) and, most likely but I am speaking entirely empirically here, fuel sources.
The body uses ATP to fuel every one of its over thirty trillion cells. But it has three primary sources for replenishing its ATP supply:
- Glucose stored in the muscles and blood
- Glucose stored in the liver
- Fat
Which it chooses to use in the very first instance is determined by the type of exercise, its intensity and its duration. For instance, casual to moderate speed walking will draw fuel directly from fat reserves, bypassing blood glucose s shown by this
study. To understand why this should be we need to get to primary causes: what is the brain's role in all this? To help us survive a world that's designed to kill us (at least that's what it was in the past when our neurobiology was perfected). How does it do that? Well, primarily by making sure that everything we do leads to an overall reduction of the energy cost of staying alive.
Walking is not a highly active state. Once we get going we pretty much settle in it and biochemically we reach a fairly steady state. The brain's logic, which activates the body; is that since we are not at risk it can afford to engage the energetically more costly and slower process of lipolysis (the breaking down of stored fat to produce carbohydrates which then re-supply our cells with ATP) so that if, for instance, during our walk we encountered a Saber-toothed tiger, we'd still be able to internally crank everything up so we can run to safety or fight it.
What does all this have to do now with your question? Plenty. If the apportioning of energy and its sources depend upon the body's perception of its neurochemical phase it stands to reason that the same activity at different times of the day will draw energy from different sources. Morning exercise (when the body feels most relaxed) may draw energy from fat reserves, while evening exercise may draw directly from blood sugars which means the intensity will be higher.
I will point out two things: First, all the scientific evidence to date is indicative but not conclusive because we lack quality research data. Second, the outcomes in speed, strength and endurance are the same regardless when you choose to train. So really it comes down to the question what are your personal aims when you exercise? What do you want to achieve?
Finally, and this is coming up a lot on this thread, you need to experiment. Every person is different. See what works best for you by following a protocol (which means you record everything) for six weeks and then see how you feel. This level of attention on what you do will take a little commitment but the results in better understanding your own body and determining what best works for you are invaluable.
I really hope this helps.
A little more seriously, think about which aspect of your exercise routine you need to fine tune, ask a question and I will come back with replies, studies, links to research as appropriate. Come back then with any follow-up questions you want. This thread will be open on February 7th and will remain open for two weeks until February 21st. When I see a question I will acknowledge it (usually with a thumbs up) and respond to it, usually within 24 hours. If I don't acknowledge your question and you're waiting for a reply please tag me, it means I missed it. (It's happened a couple of times in the past). If you're new to this, know that the AMA will be open in Discussion section of The Hive and then, after it's over, move to the Knowledge Base. If you're completely new and don't know what to expect know that it's easy-going and chatty. Check out some previous AMAs in the Knowledge Base to get a feel.
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