Submitted:
20 May 2026
Posted:
21 May 2026
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Abstract
Promoting physical activity is regarded as a key strategy to address the global pandemic of physical inactivity and the burden of chronic diseases; the notion that “exercise is medicine” has become a widely accepted consensus in public health. However, compared with the extensively discussed health benefits, the potential environmental exposure risks associated with physical activity have received far less attention from researchers and policy-makers. At the same time, emerging pollutants such as microplastics are attracting increasing concern in environmental science and public health. From the perspective of behavior and environmental exposure, this paper raises and discusses a seemingly paradoxical question: could people who are more physically active unintentionally ingest more microplastics? Drawing on existing literature and everyday behavioral logic, we analyze the characteristics of physically active individuals in terms of drinking behavior, diet, clothing choices, and exercise environments. We point out that increased hydration needs, a reliance on bottled water and sports drinks, frequent consumption of plastic-packaged foods, as well as the widespread use of synthetic fiber sportswear and plastic-based sports surfaces may all contribute, to varying degrees, to elevated microplastic exposure.This paper emphasizes that the idea presented here is not intended to undermine the health value of physical activity. Rather, it calls on researchers and practitioners to pay attention to, and where possible reduce, the plastic exposure risks that may accompany the promotion of physical activity. Future studies are needed to systematically assess differences in microplastic exposure across various levels and patterns of physical activity, and to explore safer hydration options and exercise environments, so as to maximize the net health benefits of being physically active.
Keywords:
physical activity
; microplastics
; bottled water
; environmental exposure
; health risk
Introduction
Regular physical activity prevents chronic diseases, reduces mortality, and benefits mental health, so “exercise is medicine” has become a widely accepted principle in policy and practice. However, potential adverse effects linked to the context and environment in which physical activity occurs have received much less attention. While research has focused on injuries, overtraining, or exercise addiction, it has rarely considered how modern exercise-related behaviors might increase exposure to emerging environmental hazards such as microplastics.
Microplastics, generally defined as plastic particles smaller than 5 mm (Rillig & Lehmann, 2020), originate from manufactured micro-sized plastics or the fragmentation and abrasion of larger plastic items (e.g., plastic bottle). They are now ubiquitous in oceans, fresh water, soils, and air, and have been detected in drinking water, food, human feces, and some tissues. Experimental evidence suggests potential impacts on digestive, immune, and endocrine systems (Lamoree et al., 2025), although health effects in humans remain incompletely understood.
For example, in the case of drinking water, nearly half of the water consumed by Americans comes from bottled sources (Vieux et al., 2020), suggesting an important pathway through which microplastics can enter the human body. Those physically active individuals who drink more water may therefore be exposed to an even greater level of risk. Against this backdrop, we raise a counterintuitive but important question: could people who are more physically active unintentionally ingest more microplastics? Our aim is to highlight a possible “health paradox”: in modern environments, behaviors that accompany an active lifestyle—how we drink, eat, dress, and where we exercise—may simultaneously increase microplastic exposure.
In the presented paper, we discuss four hypothesized pathways.
- Higher Hydration Needs and Plastic-bottled Beverages
Individuals engaging in regular or vigorous activity sweat more and therefore drink more frequently and in greater volumes than sedentary people. In practice, bottled water and bottled sports drinks are the dominant hydration choices in many exercise settings, driven by convenience, marketing, and the logistics of events and gyms.
Studies have detected microplastics in commercial bottled water and other bottled beverages, with plastic packaging itself acting as a source of particles (Maharjan, 2025). Storage duration, repeated use, sunlight exposure, and high temperatures can accelerate aging and fragmentation of plastics, increasing migration of microplastics into the liquid. The common practice of repeatedly refilling single-use bottles or leaving them in hot cars and training venues may further intensify this process. Thus, because active individuals drink more and rely more on plastic-bottled beverages, their cumulative microplastic intake from drinking water may be higher.
- 2.
- Post-exercise “Convenient Eating” and Plastic-packaged Foods
After intensive exercise, many people rely on quick, convenient foods for energy and protein replenishment: convenience-store snacks, vending-machine products, food-delivery meals, and prepared items sold in or near gyms. These are typically wrapped or served in plastic.
Plastic packaging can shed micro- or nano-plastic particles during production, transport, storage, heating, and microwaving (Sharma, 2024). If physically active people consume such plastic-packaged foods more frequently, their dietary microplastic exposure may be elevated. At present this remains a plausible but under-studied pathway that warrants inclusion in future research agendas.
- 3.
- Synthetic Sportswear and Microfiber Exposure
Modern sportswear relies heavily on synthetic fibers such as polyester, nylon, and spandex to achieve lightness, elasticity, moisture-wicking, quick drying, and thermal regulation. These fibers are prone to releasing microfibers during washing, wearing, friction, and aging (Yang et al., 2023).
For people who exercise frequently, friction between clothing, skin, equipment, and surfaces is intensified, potentially increasing microfiber release. Indoor training facilities can contain relatively high concentrations of textile-derived microfibers in air and settled dust. While we lack high-quality data linking sportswear-derived microfibers directly to human intake, the combination of synthetic materials, high friction, and elevated breathing rates during exercise makes this a plausible exposure route.
- 4.
- Exercise Environments: Tracks, Turf, and Urban Roads
Exercise environments themselves can be important sources of plastic-related exposure. Synthetic running tracks and artificial turf fields contain substantial amounts of rubber and plastic (Zhang et al., 2025). Under UV radiation, weathering, and mechanical wear, these materials degrade, generating debris and particles that can be found in dust, stormwater runoff, and nearby air.
Outdoor running and cycling in urban areas also coincide with elevated exposure to traffic-related particles (Järlskog et al., 2021). In addition to soot and inorganic particles, tire wear and road surface degradation contribute microplastic particles. Vigorous exercise increases breathing rate and minute ventilation, thereby increasing the number of particles inhaled per unit time. If microplastics or microfibers are present in the air around roads or sports facilities, active individuals may inhale more of them during exercise than at rest.
- 5.
- Directions for Future Research and Practice
To better understand and manage this potential paradox, several research directions are proposed:
- Behavior–exposure studies
Although numerous studies have shown that bottled water is an important source of microplastic ingestion, the hypothesized pathway whereby higher levels of physical activity lead to greater bottled-water consumption and, in turn, to increased microplastic body burden has not yet been empirically tested. Future research could use questionnaires, activity diaries, and digital tracking to compare hydration sources, plastic-bottle use, plastic-packaged food intake, and clothing choices across different activity levels, and link these behaviors to microplastic particle counts in human blood, stool, or other biological samples.
- 2.
- Environmental monitoring in exercise contexts
Measure microplastics in air, dust, and water across exercise environments (parks, roads, synthetic tracks, turf fields, indoor gyms) and combine these data with information on exercise duration and intensity.
- 3.
- Integration into existing cohorts
Incorporate simple indicators of plastic exposure into ongoing physical activity cohorts and interventions, enabling assessment of how physical activity and microplastic exposure jointly influence health outcomes.
- 4.
- Context-based interventions
Design and evaluate interventions that reduce plastic exposure without discouraging physical activity—for example, promoting safe non-plastic water fountains and reusable non-plastic bottles, or testing alternative materials and facility designs.
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