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Muscle Protein Metabolism and Requirements in Female Athletes — Transcript

by GSSI Ask The Expert · 1,830 words · 326 segments · language en · Watch on YouTube

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0:07Hi, my name is Stuart Phillips. I'm a
0:08professor in the department of
0:09kinesiology at McMaster University. This
0:12presentation highlights the key findings
0:14from a recent GSSI sports science
0:17exchange article that our team wrote.
0:19But rather than hear it from me, here
0:21are the team that did the work bring to
0:23you the goods on our paper, Muscle
0:25Protein Metabolism and Protein
0:27Requirements for Female Athletes:
0:29Aligning Science with Sex Specific
0:31Needs. Hi, I'm James Newood. I'm a
0:34master student here at McMaster
0:36University. And we'll start off by
0:37looking at how dietary protein uh
0:39supports exercise induced changes to
0:41skeletal muscle health. So athletes
0:44place extraordinary demands on their
0:46bodies with every game, practice, lift
0:49driving them to adapt and grow stronger.
0:52Now at the core of this adaptation is
0:53skeletal muscle which through consistent
0:56training it repairs, remodels and adapts
0:58leading to gains in strength, size and
1:01endurance. Now for these adaptations to
1:04occur efficiently, the body needs this
1:06proper support. And that's where
1:08nutrition, particularly protein, plays a
1:10key role in muscle recovery and growth.
1:14Now, dietary protein provides the
1:17essential amino acids that are the
1:19building blocks of new muscle protein.
1:22Now, essential amino acids allow for
1:24muscle repair, remodeling, and growth to
1:26occur after exercise. And without this
1:28dietary protein, recovery slows, muscle
1:31health declines, and the risk of injury
1:33increases. When muscles receive adequate
1:36essential amino acids, they can
1:38effectively rebuild and adapt to this
1:40training or performance. Now, research
1:43shows that consuming about 0.331
1:46g of protein per kilogram of body weight
1:49per meal achieves the most anabolic
1:52response. Any more than that and that
1:55protein is uh used for energy or simply
1:58just wasted. Now in order to achieve the
2:01maximal response the this protein intake
2:04should consist of all nine essential
2:06amino acids.
2:09Now it's helpful to know the maximum
2:11amount of protein that can be utilized
2:13at one time. But athletes should also
2:15think about consistency. So to optimize
2:18muscle recovery and growth, protein
2:20needs to be consumed regularly
2:21throughout the day, not just in one
2:23sitting. Many people tend to skew their
2:25protein intake toward dinner, leaving
2:27breakfast and lunch relatively low in
2:30protein. So this pattern means body
2:33spends much of the day in this lower
2:34anabolic state, missing valuable
2:36opportunities for repair and adaptation.
2:39So to get the most out of every meal,
2:41protein should be distributed evenly
2:43across breakfast, lunch, and dinner,
2:45which leaves the body in a more anabolic
2:47state throughout the majority of the
2:50day.
2:52Now when we're talking about athletes,
2:54this diet, total diet, daily protein
2:56intake and the uh protein distribution
3:00are equally important when it comes to
3:03uh achieving performance and and uh
3:06recovery goals.
3:09Now, while the core principles of
3:11protein metabolism apply to all
3:13athletes, female athletes experience a
3:15few additional physiological factors.
3:17things like monthly hormonal
3:18fluctuations, the effects of hormone
3:21hormonal contraceptives, and even
3:23lifestage changes like menopause. So,
3:25all of these may influence training,
3:27recovery, and nutrition. But even with
3:30the growing interest in women's health,
3:32female athletes are still under
3:33represented in sports science research.
3:36So, a lot of what we currently know
3:38about exercise protein metabolism is
3:41based on studies conducted in mainly
3:43male participants, which leaves some
3:45important gaps when it comes to female
3:46athletes. So, to tell you more about
3:48this, here's Alicia.
3:50>> Hi, I'm Alicia Duza, a PhD candidate at
3:53McMaster University where my research
3:56focuses on female muscle physiology,
3:58specifically how ovarian hormones shape
4:01training adaptations and protein
4:02metabolism. And as James mentioned, when
4:06you look at the research, less than 8%
4:08of exercise nutrition studies include
4:11female only participants. That's a
4:14pretty big gap, and filling it is
4:16crucial for building evidence-based
4:18strategies that truly support women's
4:21performance, recovery, and long-term
4:23health. Now, it's worth saying that
4:27sexbased differences in overall dietary
4:30protein needs, if they exist at all, are
4:33pretty minimal. So, why are we talking
4:36about this? It's because women don't
4:38train in the same hormonal environment
4:41every day. The menstrual cycle creates a
4:44shifting backdrop that may influence how
4:47training and nutrition interact.
4:53While the main goal of the menstrual
4:55cycle is reproduction, truthfully, it
4:58creates a constantly changing endocrine
5:01environment that may influence things
5:02like appetite, metabolism, and even how
5:05the body responds to training. Now,
5:08there are two main phases to the
5:10menstrual cycle. the follicular phase
5:12which starts on day one with
5:14menstruation where estrogen gradually
5:16rises and the ludial phase after
5:19ovulation when both estrogen and
5:22progesterone increase. But here's the
5:25key point. Ovulation doesn't reliably
5:28occur on day 14. Recent data shows that
5:32actually it can happen anywhere between
5:34day 7 and day 21. And that variability
5:37makes research and practical
5:40recommendations much trickier.
5:43Despite these challenges, early work did
5:46suggest that protein needs may need to
5:49be increased in the ludial phase as some
5:52studies found that there were slightly
5:54higher amino acid oxidation or breakdown
5:58during that phase. But when you look
6:00closely, those differences only actually
6:02amount to 3 to 5 g. So, a few bites of
6:06chicken. In other words, while
6:09physiologically it may be real,
6:11practically these differences are very,
6:14very trivial.
6:17And so, more recent and methodologically
6:20rigorous studies tell a bit of a clearer
6:22story. Research from myself and other
6:25reputable researchers in this field have
6:27found that there's no meaningful
6:29difference in resting metabolic rate, no
6:31differences in substrate use, and no
6:34differences in muscle protein synthesis
6:37or breakdown across menstrual cycle
6:39phases. And actually, IP appetite often
6:43increases in the ludial phase, leading
6:46to naturally higher energy and protein
6:48intake, which likely offsets any small
6:51metabolic differences.
6:53So what does this mean for athletes?
6:56Current evidence does not support
6:58increasing protein intake during the
7:01ludal phase. The most effective strategy
7:04is still hitting 1.4 to 1.6 g per kilo
7:09per day of protein, distributing it
7:12evenly, so every 3 to 4 hours, and
7:15focusing on total daily intake, not
7:18cycle timing.
7:20>> [snorts]
7:20>> However, not all female athletes have a
7:24natural menstrual cycle. Over half of
7:27female athletes use hormonal
7:28contraceptives.
7:30Now, combined oral contraceptives and
7:32progesterine only methods all influence
7:35hormones differently, which raises the
7:38question, do they alter protein needs?
7:41So far, the research suggests probably
7:44not. Studies comparing oral
7:46contraceptive users to naturally
7:48menrating athletes finds no meaningful
7:51difference in protein synthesis at rest
7:53or after training. There may be small
7:56differences between contraceptive types,
7:59but we don't know yet whether this
8:01affects nutrition recommendations. So,
8:03at this point, the evidence is clear.
8:06While hormones fluctuate throughout the
8:08menstrual cycle and with contraceptive
8:10use, these changes don't appear to
8:13meaningfully alter protein requirements.
8:15[gasps] Female athletes do not need to
8:17adjust their protein intake based on
8:19cycle phase or contraceptive status. The
8:22priority still remains consistent
8:25highquality protein throughout the day
8:27to support training, recovery, and
8:29performance. But there are some
8:32circumstances where protein
8:34recommendations may shift, which is what
8:36Dominique will tell you about next. Hi
8:38everyone, my name is Dominique
8:40Ravenstein and I'm an MSSE student at
8:42McMaster University. Today I'll be
8:44discussing some special considerations
8:46for protein intake for female athletes,
8:49specifically during menopause, low
8:51energy availability, and for individuals
8:53following a plant-based diet.
8:57As women transition through pmenopause
8:59and menopause, we see a gradual and
9:01nonlinear decline in estrogen production
9:04that coincides with age related losses
9:06in muscle mass, strength, and function.
9:09During this time, skeletal muscle can
9:11become less responsive to dietary
9:14protein and resistance exercise. And
9:17this phenomenon is known as anabolic
9:19resistance. Because of this, some
9:21researchers have suggested that perry
9:24and post-menopausal women may benefit
9:26from higher protein intakes of 1.8 to 2
9:29g per kilogram of body weight per day.
9:32However, current evidence indicates that
9:35the loss of muscle with age is primarily
9:37driven by aging itself rather than
9:39estrogen deficiency. We can see that in
9:42this figure here that muscle mass
9:44declines linearly with age and it is not
9:46accelerated during menopause. Supporting
9:49this, we also see that estrogen-based
9:51hormone therapy doesn't seem to prevent
9:53muscle loss. So, perry and
9:56post-menopausal athletes likely don't
9:58require higher protein intakes than
10:00premenopausal athletes. The existing
10:02athletic guidelines 1.4 to 1.6 g of
10:06protein per kilogram per day appear to
10:08be sufficient to support muscle health
10:11when combined with regular resistance
10:12exercise.
10:16Another context where protein needs may
10:18shift is during periods of low energy
10:21availability, which occurs when there's
10:23a mismatch between energy intake and
10:25exercise energy expenditure. Now, this
10:28can happen intentionally, for example,
10:30to meet body composition goals or
10:32unintentionally when high training
10:34volumes aren't matched with sufficient
10:36fueling. Now short bouts of low energy
10:39availability may not cause immediate
10:42issues but when it becomes prolonged or
10:44severe it can lead to relative energy
10:47deficiency in sport or reds. This
10:50condition is linked to menal dysfunction
10:52[snorts]
10:53reduced performance and negative effects
10:55on skeletal muscle health. To help
10:58counteract the negative effects of low
11:00energy availability on skeletal muscle,
11:02resistance exercise should be a priority
11:05as muscle loading is the most powerful
11:07stimulus for preserving lean tissue.
11:09Also, increasing protein to 1.6 to 2.2 g
11:13per kilogram per day can help support
11:15muscle mass retention during this time.
11:18We're also seeing a growing number of
11:19female athletes adopt vegetarian or
11:21plant-based diets. We can see this trend
11:23in a survey of 1,628
11:26female runners where 40% reported
11:28following a vegan diet and 23% reported
11:31following a vegetarian diet. Plant-based
11:35proteins are sometimes considered
11:36inferior to animal-based ones because
11:39they're less digest digestible and lower
11:41in certain essential amino acids.
11:43However, when total protein intake is
11:45sufficient and includes complimentary
11:47sources, vegan and plant-based diets can
11:50elicit anabolic responses comparable to
11:52animal-derived proteins. So,
11:54plant-focused athletes should emphasize
11:56a wide variety of protein sources and
11:58may benefit from targeting the higher
12:00end of protein recommendations, closer
12:02to 1.6 g per kilogram per day to offset
12:05the lower essential amino acid content
12:07of plant-based foods. Overall, current
12:10evidence suggests that well-planned
12:12vegetarian and vegan diets do not
12:14inherently disadvantage athletes as long
12:17as total protein intake is adequate. In
12:20summary, female athletes experience
12:22unique hormonal transitions and
12:25physiological demands across their
12:26lifespan, but the fundamentals of
12:29protein nutrition remains consistent.
12:31The evidence supports an individualized
12:33approach that focuses on total daily
12:36intake, balanced meal distribution, and
12:39overall dietary context rather than
12:42adjusting protein needs based solely on
12:44the menstrual cycle or contraceptive
12:46use. Whether you're young and healthy,
12:49facing energy deficits, experiencing
12:52menopause, or following a plant-based
12:54diet, combining resistance training with
12:57protein intakes around 1.4 to 1.6 6 g
13:01per kilogram per day provides a strong
13:04foundation for muscle health performance
13:07and long-term well-being. And for
13:09practitioners, ultimately empowering
13:12female athletes with clear,
13:15evidenceinformed guidance is key to
13:17fueling success. Feel free to use our
13:20summary image and share that with your
13:22athletes.
13:24Thank you so much for listening and we
13:26hope you enjoy reading our paper.

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