Females have a blunted cardiovascular response to one year of intensive supervised endurance training.
Level 3 - non-randomized controlled study
Prospective non-randomized comparative cohort study evaluating longitudinal physiological adaptations.
PubMed 25930024 · doi:10.1152/japplphysiol.00092.2015
What was done
Twelve previously sedentary adults (7 males aged 26 ± 7 years; 5 females aged 31 ± 6 years) completed a 1-year progressive endurance training program matched for exercise volume and intensity. Every 3 months, participants were evaluated for maximal oxygen uptake (VO2max) and left ventricular (LV) morphology and function using cardiac magnetic resonance imaging. Pulmonary artery catheterization was performed before and after training to assess pressure-volume and Starling curves under lower-body negative pressure and saline infusion.
What was found
Males showed progressive increases in VO2max, LV mass, and mean LV wall thickness, plateauing between months 9 and 12. In females, increases in VO2max, LV mass, and mean wall thickness plateaued after 3 months. Left ventricular end-diastolic volume increased similarly in both groups (+20% in males vs. +18% in females). Starling curves shifted upward and to the left post-training, with a trend toward a greater effect in males (interaction P = 0.06).
Why it matters
This study suggests that males and females have divergent cardiac remodeling trajectories during long-term endurance training, with females experiencing earlier plateaus in ventricular hypertrophy and VO2max gains despite identical training volume and intensity.
Limits
The sample size was very small (n = 12 total, including only 5 females). Absolute values and effect sizes for VO2max, LV mass, and wall thickness were not reported in the abstract. There was no non-exercising control group.
Cited by
- supports In a year-long training study, women increased their heart size during the first three months similarly to men but then plateaued, whereas men continued to increase heart size.