What does this research mean for the field?

Experimental matching of blood volume and oxygen carrying capacity between healthy young men and women abolishes the sex differences in peak oxygen uptake and cardiac output. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

March 17, 2022Frontiers in PhysiologyOpen Access

Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity

Q: What is the clinical evidence from this study?

Population: Healthy young individuals (n=28). Intervention: Blood normalization (blood withdrawal and CO rebreathing) vs. Baseline (unaltered blood volume and O2 carrying capacity). Primary outcome: Peak oxygen uptake (VO2peak) after blood normalization (p=0.416).

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Key result

Matching blood volume and oxygen carrying capacity abolishes the sex difference in VO2peak.

P=0.416
n=28

Why the study?

Whether average sex differences in cardiorespiratory fitness can be mainly explained by blood inequalities in the healthy circulatory system remained unresolved.

Does matching blood volume and oxygen carrying capacity eliminate sex differences in cardiac output and aerobic capacity in healthy young adults?

Population

28 healthy young women and men aged 20–43 years matched by age and physical activity

Comparison

Men before vs after blood withdrawal and reduction of O2 carrying capacity to reach women's levels

Authors

CDCandela Díaz-CañestroUniversity of Zurich BPBrandon PentzUniversity of Calgary ASArshia SehgalUniversity of Calgary

Discussion

Member takes

Implication

Challenges intrinsic cardiac explanations for sex differences in aerobic capacity; leaves open translation to clinical or older populations.

Structured PICO

Does matching blood volume and oxygen carrying capacity eliminate sex differences in cardiac output and aerobic capacity in healthy young adults?

Population

28 healthy young adults (women and men, age range 20–43 years) matched by age and physical activity, with no history of cardiac, pulmonary, or neuromuscular diseases.

Intervention

Blood normalization in men: blood withdrawal (8.1 ± 2.3 ml/kg) and reduction of oxygen carrying capacity via carbon monoxide rebreathing to match women's levels.

Comparator

Baseline measurements in men (prior to blood normalization) and matched healthy women.

Outcome

Cardiac output (Q) and aerobic capacity (peak oxygen uptake, VO2peak) during incremental exercise.surrogate

Main Result

Absolute Event Rate: 40% vs 42%

p-value: p=0.416

Sex differences in cardiac output and aerobic capacity in healthy young adults are primarily explained by differences in blood volume and oxygen carrying capacity rather than inherent cardiac limitations.

Limitations

The potential influence of the menstrual phase on blood flow distribution during exercise, venous compliance, and body composition was not controlled.
Potential unsought effects of -50 mmHg LBNP on central hemodynamics during acute leg cycling exercise remain to be assessed.
The second testing (blood normalization) session was not performed in women, so ordering effects were not controlled.
The experimental approach takes female blood volume and O2 carrying capacity as the control variables, rather than expanding female blood volume to match men.
The opposite approach (increasing blood volume and O2 carrying capacity in women to the level of men) was not implemented due to methodological constraints of autologous blood transfusion.
Extrapolation of peripheral vasodilation mechanisms to young individuals remains speculative.

Cite This Study

Díaz-Cañestro et al. (2022) studied Healthy young individuals (n=28). Blood normalization (blood withdrawal and CO rebreathing) vs. Baseline (unaltered blood volume and O2 carrying capacity) was evaluated on Peak oxygen uptake (VO2peak) after blood normalization (p=0.416). Experimental matching of blood volume and oxygen carrying capacity between healthy young men and women abolished the sex difference in peak oxygen uptake (40 vs 42 ml/min/kg, P=0.416).

synapsesocial.com/papers/6a17dc0685d86a2c3d1c847a https://doi.org/10.3389/fphys.2022.747903

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Implication

Challenges intrinsic cardiac explanations for sex differences in aerobic capacity; leaves open translation to clinical or older populations.

Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity

Discussion

Member takes

Implication

Structured PICO

Main Result

Limitations

Cite This Study

Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity

Discussion

Member takes

Implication

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider