It’s well known that exercise reduces the risk of cancers but practical considerations render it unfeasible for the majority of adults.
Structured exercise is often perceived as time-consuming, demanding a significant commitment and, in many cases, necessitating financial expenditure or travel to a gym.
Little research has been conducted on the potential of incidental physical activity in terms of cancer risk reduction.
Incidental activities encompass tasks like running errands on foot, work-related physical activity, or integrating housework into daily routines. As a result, they do not necessitate an additional time commitment, specialized equipment, or specific logistical arrangements.
These activities could include short power walks to reach the bus or tram stop, ascending stairs, carrying heavy groceries, engaging in active household chores, or participating in energetic play with children.
How was the study conducted?
In the study, 22,398 UK Biobank participants who had never received a cancer diagnosis and did not engage in structured exercise during their leisure time were included.
Approximately 55 percent of the participants were female, with an average age of 62. Wrist activity trackers were worn by the participants for a week. These trackers continuously monitored activity levels throughout the day, providing us with a detailed account of how vigorously and for what duration individuals in the study were engaging in physical activity.
Subsequently, participants’ activity data and other relevant information were linked to future cancer registrations and other health records related to cancer for a period of 6.7 years.
This allowed for the estimation of cancer risk across different levels of what we refer to as “vigorous intermittent lifestyle physical activity,” which encompasses the incidental bursts of activity in everyday life.
Additionally, a separate analysis was conducted for a group of 13 cancer sites in the body that have well-established associations with exercise, including breast, lung, liver, and bowel cancers.
Our analyses accounted for other factors known to influence cancer risk, such as age, smoking, diet, and alcohol consumption.
What Was Discovered
Despite the absence of structured exercise among study participants, approximately 94 percent of them registered brief bursts of vigorous activity. Up to one minute was the duration of about 92 percent of all such episodes.
An association was observed between a minimum of approximately 3.5 minutes of daily activity and a reduction in total cancer risk by 17–18 percent, in contrast to not engaging in such activity.
In the case of at least 4.5 minutes of daily activity, half of the participants experienced a 20–21 percent reduction in total cancer risk.
For cancers like breast, lung, and bowel cancers, which we are aware are influenced by an individual’s exercise levels, the outcomes displayed greater strength and a more pronounced reduction in risk.
For instance, a daily minimum of 3.5 minutes of vigorous incidental activity led to a 28–29 percent reduction in the risk of these cancers. At 4.5 minutes per day, these risks were reduced by 31–32 percent.
The results, both for overall cancer risk and those cancers known to be influenced by exercise, unequivocally demonstrate the advantages of pursuing day-to-day activities with the level of enthusiasm that induces heavy breathing and exertion.
Limitations of The Study
Our study had certain limitations. It should be noted that our study falls into the category of observational research, which entails retrospectively examining a group of individuals and their outcomes, without testing new interventions. Consequently, it cannot definitively establish cause-and-effect relationships.
Nonetheless, we implemented various statistical measures aimed at reducing the likelihood that those individuals with the lowest activity levels were also the unhealthiest, thus being more prone to developing cancer—a phenomenon referred to as “reverse causation.”
The biological mechanisms underlying the potential reduction in cancer risk due to vigorous intensity activity remain unexplained by our study. Earlier preliminary trials have indicated that this type of activity leads to rapid enhancements in heart and lung fitness. Elevated fitness levels are associated with reduced insulin resistance and diminished chronic inflammation, both of which are risk factors for cancer.
Research on the connection between incidental physical activity and cancer is scarce in general. This scarcity exists because the majority of scientific evidence concerning lifestyle and cancer is questionnaire-based. This method fails to capture brief bursts of activity and is highly inaccurate when it comes to quantifying everyday incidental activities.
As a result, despite some recent promising discoveries suggesting that engaging in vigorous activity in short episodes throughout the week could reduce health risks, the field of vigorous intensity activity and its relationship with cancer risk is still in its early stages.
In another recent study conducted by our team, we uncovered benefits associated with daily vigorous intermittent lifestyle activity in terms of overall mortality risk and mortality specifically related to cancer or cardiovascular causes.
Summary
In our study, it was discovered that 3 to 4 minutes of incidental vigorous activity per day are associated with a reduced risk of cancer. This amount of activity is notably smaller when compared to the current recommendations, which suggest 150–300 minutes of moderate-intensity or 75–150 minutes of vigorous-intensity activity per week.
Vigorous incidental physical activity presents a promising avenue for cancer prevention among individuals who may be unable or lack motivation to engage in structured exercise during their leisure time.
Furthermore, the potential of technology is underscored by our study’s findings. These results offer just a glimpse of how wearables, in combination with machine learning, as employed in our study to identify brief bursts of vigorous activity, can unveil health benefits associated with previously unexamined facets of our daily lives.
The future impact potential of such technologies in cancer prevention, as well as potentially addressing a range of other health conditions, is substantial.
Abstract
Importance
Vigorous physical activity (VPA) is a time-efficient way to achieve recommended physical activity (PA) for cancer prevention, although structured longer bouts of VPA (via traditional exercise) are unappealing or inaccessible to many individuals.
Objectives
To evaluate the dose-response association of device-measured daily vigorous intermittent lifestyle physical activity (VILPA) with incident cancer, and to estimate the minimal dose required for a risk reduction of 50% of the maximum reduction.
Design, Setting, and Participants
This was a prospective cohort analysis of 22 398 self-reported nonexercising adults from the UK Biobank accelerometry subsample. Participants were followed up through October 30, 2021 (mortality and hospitalizations), or June 30, 2021 (cancer registrations).
Exposures
Daily VILPA of up to 1 and up to 2 minutes, assessed by accelerometers worn on participants’ dominant wrist.
Main Outcomes and Measures
Incidence of total cancer and PA-related cancer (a composite outcome of 13 cancer sites associated with low PA levels). Hazard ratios and 95% CIs were estimated using cubic splines adjusted for age, sex, education level, smoking status, alcohol consumption, sleep duration, fruit and vegetable consumption, parental cancer history, light- and moderate-intensity PA, and VPA from bouts of more than 1 or 2 minute(s), as appropriate.
Results
The study sample comprised 22 398 participants (mean [SD] age, 62.0 [7.6] years; 10 122 [45.2%] men and 12 276 [54.8%] women; 21 509 [96.0%] White individuals). During a mean (SD) follow-up of 6.7 (1.2) years (149 650 person-years), 2356 total incident cancer events occurred, 1084 owing to PA-related cancer. Almost all (92.3%) of VILPA was accrued in bouts of up to 1 minute. Daily VILPA duration was associated with outcomes in a near-linear manner, with steeper dose-response curves for PA-related cancer than total cancer incidence. Compared with no VILPA, the median daily VILPA duration of bouts up to 1 minute (4.5 minutes per day) was associated with an HR of 0.80 (95% CI, 0.69-0.92) for total cancer and 0.69 (95% CI, 0.55-0.86) for PA-related cancer. The minimal dose was 3.4 minutes per day for total (HR, 0.83; 95% CI, 0.73-0.93) and 3.7 minutes for PA-related (HR, 0.72; 95% CI, 0.59-0.88) cancer incidence. Findings were similar for VILPA bout of up to 2 minutes.
Conclusions and Relevance
The findings of this prospective cohort study indicate that small amounts of VILPA were associated with lower incident cancer risk. Daily VILPA may be a promising intervention for cancer prevention in populations not able or motivated to exercise in leisure time.