In affluent, industrialized countries, we hear a lot about children’s lack of physical activity. What gets mentioned less often is the seasonal component: Contrary to what we might expect, kids tend to become less active during the summer months, and less physically fit. How big is the shortfall, and what can we do to combat it?
Brisk walking. Skateboarding. Biking on a level road. These are examples of what researchers call “moderate intensity physical activity.”
Move up a level to vigorous activity, and we’re talking about things like jogging and playing basketball.
Lump these altogether, and we get “moderate-to-vigorous physical activity”, or MVPA.
How much MVPA should kids be getting each day?
If we want to know what’s been normal over the course of human evolution, it makes sense to check on the habits of contemporary hunter-gathers — the folks whose lifeways most closely resemble those of our ancestors. And if we do this, we find that kids are very active indeed. For instance, among the BaYaka people, children get an average of 3 hours of MVPA each day (Kretschmer et al 2023).
But the World Health Organization has issued a more modest recommendation for us: about 60 minutes of MVPA each day for kids between 6 and 17.
Are kids in industrialized countries meeting this target?
Unfortunately, no. Most are falling far short (Rollo et al 2020). And this assessment is based on measurements taken during the school year. If we ask instead how kids are faring during the summer break, the picture gets even worse.
So how do we know this stuff, and what can we do about it? Let’s take a quick look at the evidence.
Evidence: Kids tend to become more sedentary over the summer
In a recent analysis, researchers reviewed the results of several studies reporting on changes in children’s health behaviors during the summer (Eglitis et al 2024). What did they find?
In 5 out of 7 studies, kids actually became more sedentary during the summer.
Now, these weren’t necessarily big increases in sedentism — and certainly not for everyone across the board. But it’s eye-opening when you remember that most kids are already too inactive. So what about MVPA? Does that change as well?
Summertime fitness deficit: Kids get less MVPA
It would be easy to ask kids to estimate their activity levels, but the results can be unreliable. So Amanda Watson and her colleagues used an objective measure — wrist accelerometers (like a Fitbit) — to detect a summertime drop-off in MVPA among 9-year-old children in Australia.
The researchers monitored children at 5 different time points over the course of two years — measuring children’s activity levels both during the school year, and during the summer. And the results?
On average, kids spent about 27 more minutes per day being sedentary…and about 12 minutes less each day engaging in moderate-to-vigorous physical activity (Watson et al 2023).
Assuming this 12 minute drop in MVPA is pretty accurate, how meaningful is it from the standpoint of children’s health and fitness? Further research suggests that it makes a difference.
Children’s summertime losses in cardiovascular endurance
In a related study, the same research team tracked differences in aerobic fitness using the shuttle run test, also known as the Progressive Aerobic Cardiovascular Endurance Run (PACER). This is where you have to keep running 20 meters, back and forth, at an ever-faster pace. The more laps you can run, the higher your cardiovascular fitness.
Once again, researchers began their study with kids who were approximately 9 years old. Once again, they tested kids at multiple points over a two-year time span.
And unfortunately, the researchers detected a rapid decline in physical fitness over the summer holiday break. Compared to their performance at the end of the school term, kids returning to school after the summer break ran out of steam faster (Olds et al 2023).
Researchers in the United States have reported similar findings for kids in the upper grades of primary school, with the biggest decline in aerobic fitness documented among the older children: Whereas 6th graders averaged about 43 PACER laps at the end of the school year, they completed only about 27 laps after returning to school from their summer break (Fu et al 2017).
So there’s a pattern of reduced physical activity during the summer, and a related decline in aerobic fitness. It doesn’t exactly harmonize with traditional images of childhood during the summer – kids freed from the classroom, enjoying lots of exercise and outdoor recreation.
Why are kids experiencing summer fitness loss?
We can point to big changes in the popular culture — like the rise of video games, social media, and the perception that kids aren’t safe outside unless they are being continually monitored by adults. But there are other factors too. Summer heat waves, wildfire smoke, and other weather-related conditions can actively prevent us from exercising outdoors (Watson et al 2023).
But all of this goes to show that we can’t take it for granted that kids will engage in healthful levels of physical activity merely because it’s summer break.
In the same way that many children experience summer learning loss, children may also suffer declines in physical fitness. And it’s worth remembering that these two areas of life are not disconnected. As I note here, there is evidence that aerobic exercise can help kids improve their cognitive functioning.
What can we do to boost children’s fitness levels?
1. When weather conditions permit, get kids outside – but don’t assume that will be enough.
As I explain in my article about outdoor play, getting kids outside has many health benefits, and it can boost rates of moderate-to-vigorous physical activity. However, it doesn’t always make much difference – perhaps especially among older children (Larouche et al 2018). So don’t stop there.
2. Help kids connect with active peers and safe, inviting spaces to exercise.
Although it isn’t rocket science, the research is worth mentioning. Children – young children in particular – tend to exercise more when they are hanging out with friends or siblings (Pearce et al 2014), and the immediate environment makes a difference. Kids get more active when they have access to stimulating playground structures (Gustat et al 2023), and when their urban neighborhoods close off street traffic to make space for safe play (d’Haease et al 2015).
In addition, some older kids may require more structure and accountability to stay active, in which case team sports (Pearse et al 2018) and fitness classes can be helpful.
3. Promote nature walks.
Walking in natural, green environments doesn’t just fight sedentism and boost cardiovascular fitness. As I note elsewhere, it can also lift our moods, reduce stress, and stop us from brooding.
4. Frustrated because you have very young children, and need to get a workout yourself?
Taking your toddler for walk — or monitoring outdoor play — is a form of activity for yourself, but it probably doesn’t rate as moderate-to-vigorous physical activity. Not for your adult-sized body. My solution? I didn’t have any childcare helpers when I took my kids out, so I did this: Get them playing in the middle of a field or park, and then do laps around them. It might look goofy to passersby, but it allows you to get some real exercise while staying in visual contact with a young child.
5. For de-motivated older kids, consider using a fitness tracker.
You might not want to resort to technology, but if your child lacks the motivation to move, gamifying it with a fitness tracker could be helpful.
In a meta-analysis of published studies, researchers didn’t find evidence that fitness trackers, by themselves, increased moderate-to-vigorous activity. But – in combination with other efforts – the use of fitness trackers led to reductions in sedentary behavior and increases in light physical activity. Kids were also more likely to experience enhancements in muscle strength and agility (Wang et al 2024).
And among children who are obese, fitness tracking apps (that encourage both exercise and dietary changes) can help kids lower their BMIs (e.g., Tugault-Lafleur et al 2023).
6. Get your kids to walk (and play with) the dog!
Studies suggest that merely owning a dog doesn’t increase children’s fitness levels. But when adolescents take on the responsibility of walking the family dog, they end up getting more exercise – including more moderate-to-vigorous physical activity (Pajaujiene and Petrigna 2024).
7. Stuck indoors because of the heat or bad air quality? Try martial arts…or aerobic dancing.
Whether your kids prefer to boogie, or practice their snap-kicks, both pastimes can come with heavy doses of moderate-to-vigorous physical activity. In fact, a recent review of the effects of martial arts participation in kids, researchers found that young martial artists don’t just improve their cardiovascular fitness. They also experience gains in strength, agility, coordination, speed, and balance (Stamenković et al 2022).
And dancing? If you’re looking to improve your child’s cardiovascular fitness, be aware that many dance classes don’t seem to deliver notable gains (Dos Santos et al 2021). The trick is to make sure kids are spending substantial portions of their time in high-intensity exercise – not just waiting around between sets, or working on subtle aspects of their technique. Learning technique and choreography is great…but it might not always tick the boxes for MVPA.
More reading from Gwen Dewar and Parenting Science
If you’re curious about what else can go wrong during the summer, check out my article about summer learning loss. And for more information about health and exercise in children, see these articles:
References: Summer fitness in children
D’Haese S, Van Dyck D, De Bourdeaudhuij I, Deforche B, Cardon G. 2015. Organizing “Play Streets” during school vacations can increase physical activity and decrease sedentary time in children. Int J Behav Nutr Phys Act. 12:14.
Dos Santos GC, Queiroz JDN, Reischak-Oliveira Á, Rodrigues-Krause J. 2021. Effects of dancing on physical activity levels of children and adolescents: a systematic review. Complement Ther Med. 56:102586.
Eglitis E, Miatke A, Virgara R, Machell A, Olds T, Richardson M, Maher C. 2024. Children’s Health, Wellbeing and Academic Outcomes over the Summer Holidays: A Scoping Review. Children. 11(3):287.
Fu Y, Brusseau TA, Hannon JC, and Burns RD. 2017. Effect of a 12-Week Summer Break on School Day Physical Activity and Health-Related Fitness in Low-Income Children from CSPAP Schools. J Environ Public Health. 2017:9760817.
Gustat J, Anderson CE, and Slater SJ. 2023. Association of Playground “Playability” With Physical Activity and Energy Expenditure. Prev Chronic Dis. 20:E33.
Olds T, Dumuid D, Eglitis E, Golley R, Fraysse F, Miatke A, Tomkinson GR, Watson A, Munzberg M, Maher C. 2023. Changes in fitness and fatness in Australian schoolchildren during the summer holidays: fitness lost, fatness regained? A cohort study. BMC Public Health. 23(1):2094.
Pajaujiene S and Petrigna L. 2024. Walking and Playing with the Dog to Improve the Physical Activity Level of Adolescents: A Scoping Review. Healthcare (Basel). 12(6):631.
Pearce M, Page AS, Griffin TP, Cooper AR. 2014. Who children spend time with after school: associations with objectively recorded indoor and outdoor physical activity. Int J Behav Nutr Phys Act. 11(1):45
Pearce M, Saunders DH, Allison P, Turner AP. 2018. Indoor and Outdoor Context-Specific Contributions to Early Adolescent Moderate to Vigorous Physical Activity as Measured by Combined Diary, Accelerometer, and GPS. J Phys Act Health. 15(1):40-45.
Rollo S, Antsygina O, Tremblay MS. The whole day matters: Understanding 24-hour movement guideline adherence and relationships with health indicators across the lifespan. J Sport Health Sci. 2020 Dec;9(6):493-510.
Stamenković A, Manić M, Roklicer R, Trivić T, Malović P, Drid P. 2022. Effects of Participating in Martial Arts in Children: A Systematic Review. Children (Basel). 9(8):1203.
Tugault-Lafleur CN, De-Jongh González O, Macdonald J, Bradbury J, Warshawski T, Ball GDC, Morrison K, Ho J, Hamilton J, Buchholz A, Mâsse L. 2023. Efficacy of the Aim2Be Intervention in Changing Lifestyle Behaviors Among Adolescents With Overweight and Obesity: Randomized Controlled Trial. J Med Internet Res. 25:e38545.
Wang JW, Zhu Z, Shuling Z, Fan J, Jin Y, Gao ZL, Chen WD, Li X. 2024. Effectiveness of mHealth App-Based Interventions for Increasing Physical Activity and Improving Physical Fitness in Children and Adolescents: Systematic Review and Meta-Analysis. JMIR Mhealth Uhealth 12:e51478.
Watson A, Maher C, Golley R, Dumuid D, Manson A, Tomkinson G, Fraysse F, Olds T. 2023. Children’s activity and diet behaviours in the summer holidays versus school year. Pediatr Obes. 18(7):e13029.
Weaver RG, Hensing C, Armstrong B, Adams EL, Beets M. 2022. Seasonal Shifts in Children’s Sedentary Behaviors, Physical Activity, and Sleep: A Systematic Review and meta-Analysis. Pediatr Clin North Am. 69(4):671-693.
image of young girl at playground, with her head buried in her phone by shutterstock / Macky Albor
