One of the most common statements spoken on playgrounds, in sports commentary, and even in casual adult conversations is the idea that “girls can’t run as fast as boys.” While this belief might seem like an observation grounded in experience, it deserves a closer look through the lens of sports science, human physiology, and sociocultural dynamics.
As sports scientists, our job is to dissect such claims using data, biological principles, and developmental science. So let’s explore: Is it true that girls can’t run as fast as boys? If so, why? And is it biological, social, or both?
Prepubescent Children: Are There Real Differences?
In early childhood — roughly between the ages of 3 to 10 years — biological sex differences in performance are minimal.
What the science says:
- Prior to puberty, testosterone levels are similar in boys and girls.
- There are no significant differences in hemoglobin levels, muscle cross-sectional area, or anaerobic enzyme activity.
- Anthropometric measures such as leg length, stride frequency, and limb leverage are not significantly different in early childhood.
So when we observe that a 7-year-old boy might be running faster than a girl, it’s crucial to question why that’s happening — because it’s not necessarily due to biology.
Skill Development: The Role of Environment and Expectation
Throwing, Running, Jumping – It’s Not Just Muscles
Take overhand throwing as an example. Research (Thomas & French, 1985) shows that boys outperform girls in this skill as early as 3 years old, and the gap widens with age. But this skill is not innate — it’s highly practiced. Boys are often socially encouraged to throw balls, join sports like cricket or baseball, or engage in rough play, whereas girls may be steered toward activities deemed more “feminine,” like dance or gymnastics.
When it comes to running, the discrepancy isn’t as large. In fact, studies (Malina et al., 2004) show that until puberty, boys and girls have comparable running speeds, especially in short-distance sprints. Any minor differences observed are likely due to:
- More exposure to competitive running in boys.
- Confidence and encouragement in boys to “go all out.”
- Stereotypes that dissuade girls from engaging in high-intensity play.
Puberty and Performance Divergence: Where Biology Does Kick In
Around the age of 11–13 in girls and 12–14 in boys, puberty introduces marked differences in hormonal profiles, particularly due to a surge in testosterone in males.
Key Biological Changes in Boys Post-Puberty:
- Increased muscle mass, especially in the upper body and lower limbs.
- Greater production of hemoglobin and red blood cells → improved oxygen delivery.
- Longer limb length and improved mechanical advantage (stride length, force production).
- Lower body fat percentage compared to females, which aids in performance for weight-bearing activities.
These changes contribute to increased anaerobic power, aerobic capacity (VO₂ max), and neuromuscular efficiency— resulting in improved running speed and endurance.
So yes, post-puberty, boys on average run faster than girls — but not because they’re inherently more athletic, rather because of specific physiological changes induced by hormones.
So What About Before Puberty?
Let’s revisit the original statement: “Girls can’t run as fast as boys.” This is false — particularly before puberty.
True Facts Before Puberty:
- Boys and girls have similar physiological potential.
- Performance differences are largely a result of practice, exposure, and encouragement.
- If girls are given equal opportunities, coaching, and reinforcement, they often match or even exceed boys in various motor tasks.
Example from Sport Science:
In a longitudinal study conducted by Barnett et al. (2010), girls who participated in structured fundamental movement skills (FMS) training showed greater improvements in sprint speed and agility than untrained boys of the same age. This emphasizes the plasticity of motor skill development and the critical role of training and environment.
Cultural Norms and Skill Development
Sociocultural expectations deeply influence which motor skills children develop. For example:
- “Boys shouldn’t skip” → Poor skipping and rhythmic coordination in boys.
- “Girls shouldn’t sweat or get dirty” → Less aggressive play, limiting anaerobic development.
These attitudes reinforce disparities in perceived competence, even when the biological capacity is similar.
The Pygmalion Effect in Physical Development:
When a child is expected to perform better or worse based on gender, their environment — teachers, coaches, parents — unconsciously shapes those expectations into reality. This is evident in school PE programs where boys are often given more challenging physical tasks.
Conclusion: Busting the Myth
So, can girls run as fast as boys? Yes, especially in the early developmental stages. The real culprits behind differences in performance are:
- Unequal access to training and sport.
- Sociocultural beliefs and biases.
- Post-pubertal physiological divergence, not early-life biology.
As educators, and parents, we must challenge these stereotypes and focus on skill acquisition, training quality, and equal encouragement for all children — regardless of gender.
Let’s stop repeating outdated myths and start training the potential we see in every child.
References
- Malina, R.M., Bouchard, C., & Bar-Or, O. (2004). Growth, Maturation, and Physical Activity. Human Kinetics.
- Thomas, J. R., & French, K. E. (1985). Gender differences across age in motor performance: A meta-analysis. Psychological Bulletin, 98(2), 260–282.
- Barnett, L.M., et al. (2010). The effectiveness of a motor skill intervention in preschool children: A randomized controlled trial. Pediatrics, 125(2), e318–e326.
- Lloyd, R.S., et al. (2016). National Strength and Conditioning Association position statement on long-term athletic development. J Strength Cond Res, 30(6), 1491–1509.