Pregnancy is a
time of profound physical and emotional change, and for many women, it raises
critical questions about fitness routines, particularly weight lifting. Common
wisdom and cautious voices often warn against the risks of heavy lifting during
these delicate nine months. However, is this advice grounded in solid
scientific evidence, or is it a case of outdated myths masquerading as medical
counsel?
Recent studies
paint a more nuanced picture. While traditional guidelines have long cautioned
against lifting over 11kg, citing occupational studies linking such activities
to potential adverse effects, the actual evidence supporting these claims is
surprisingly thin – categorised as low to very low in certainty. The context of
these studies – occupational settings – is vastly different from the controlled
environment of recreational or fitness-focused weightlifting. Below is FASTER trainer Hope showing her journey through pregnancy while simultaneously lifting!
In addition
to the concerns previously raised about heavy lifting during pregnancy, there
are several other factors that have sparked apprehension:
- Stressing the
Pelvic Floor: There has been a belief that weightlifting could potentially
increase the risk of urinary incontinence during pregnancy. However, the
combined impact of pregnancy and engaging in heavy weightlifting on urinary
incontinence and other pelvic floor disorders remains a topic of uncertainty.
Research in this area is still evolving, and a comprehensive understanding of
the relationship is yet to be established.
·
- Increased Blood
Pressure: Prenatal physical guidelines caution against the Valsalva maneuver,
which is the body's natural response to lifting a heavy load. This caution
arises from concerns about a sudden rise in blood pressure. While some
small-scale studies have indicated that the Valsalva maneuver during pregnancy
may not be associated with adverse outcomes, it's crucial to note that these
findings are primarily based on lifting relatively low loads. The impact of
this maneuver during more intense weightlifting routines remains an area that
warrants further investigation.
·
- Supine Exercises:
Performing exercises in a supine position (lying flat on the back) is
discouraged from around 16 weeks of pregnancy due to the potential compression
of the vena cava and aorta, which could lead to hypotension and reduced fetal
oxygen supply. However, a recent review of existing evidence suggests that
while compression does occur, the majority of individuals do not exhibit
symptoms of hypotension during such exercises. Despite this, the overall
evidence regarding whether exercises in a supine position are linked to adverse
outcomes during pregnancy remains inconclusive, and more research is needed to
establish a definitive stance on this matter.
In the world of pregnancy
and exercise, it's important to understand that certain guidelines aren't
necessarily rooted in concrete research that definitively proves activities
like heavy resistance training, employing the Valsalva maneuver, or engaging in
supine exercises are inherently dangerous for both the expectant mother and the
developing fetus. Instead, these recommendations tend to err on the side of
caution, which is completely understandable given the delicate nature of
pregnancy.
When it comes to
challenging established medical guidelines that might be overly conservative,
the process is usually a two-step journey. It's often not feasible to kick
things off with randomized controlled trials since ethics boards are naturally
risk-averse and unlikely to approve a controlled study involving a treatment
believed to have significant potential harm.
The initial step in
reevaluating an overly cautious recommendation often involves uncontrolled
cohort studies. These studies seek out individuals who have already made the
conscious choice to engage in behaviors deemed risky, and researchers observe
the outcomes of their voluntary actions.
When researchers conduct
several observational studies on a specific subject, consistently finding that
an activity considered perilous doesn't seem to result in the expected adverse
effects, ethics boards tend to become more receptive to greenlighting controlled
studies on that topic.
Research spotlight: Prevett
C, Kimber ML, Forner L, de Vivo M, Davenport MH. Impact of heavy resistance
training on pregnancy and postpartum health outcomes. Int Urogynecol J. 2023
Feb;34(2):405-411. doi: 10.1007/s00192-022-05393-1. Epub 2022 Nov 4. PMID:
36331580.
A
2022 cross sectional survey did exactly this by collecting data from 679
individuals who lifted at least 80% of their one rep max during pregnancy to
explore if they were at a heightened risk for adverse birth outcomes, adverse
fetal outcomes, or pelvic floor dysfunction.
Researchers
recruited lifters to complete a questionnaire consisting of 60 questions,
including sport history, reproductive history, pregnancy health outcomes and
pre-pregnancy/pregnancy/postpartum aerobic and resistance training
characteristics.
Participants
needed to have engaged in resistance training during pregnancy with loads
exceeding 80% of 1RM and to be at least 18 years old.
Summary
of main findings
• 85% continued to engage in heavy weightlifting (with or without modification) until delivery.
• 24% maintained pre pregnancy training levels throughout.
• The majority engaged in Olympic weightlifting (72%) and supine exercises (71%), whereas only a minority reported using the Valsalva maneuver (34%).
• 37% experienced urinary incontinence during pregnancy.
• The majority (89%) of respondents returned to weightlifting at around 3 months following delivery.
• Pregnancy or delivery complications were reported by 34% during, and 20% following pregnancy.
• Prevalence of pregnancy and delivery complications were largely not different between those who engaged in Olympic lifting, Valsalva maneuver, or supine exercise, compared with those who did not.
• Rates of gestational hypertension, preeclampsia and gestational diabetes were below prevalence values for the general population.
• Those who maintained pre pregnancy training levels experienced less pregnancy and delivery complications than those who reduced their training.
Since
this type of study is observational in nature, causation between the people’s
behaviours in the study and their outcomes cannot be established.
However,
the results are certainly of note because they suggest that heavy lifting, use
of Valsalva and supine exercises are not as dangerous as previously believed.
Whist this will pave the way for more studies and controlled trials, we still
can’t say with absolute certainty that existing guidelines are too cautious.
When
it comes to coaching your client, you can help them to make an informed
decision by relaying that research is beginning to push the boundaries on what
is considered safe exercise during pregnancy.
And
while there are many individuals who continue to engage in heavy lifting during
pregnancy, your client needs to do what is best for them and how they feel,
factoring their current skill level. Recognising signs of overexertion, such as
dizziness, shortness of breath, or pain, is crucial.
