With the large cross-sectional study, we have found that both WW and regularly active adults exhibited lower risk of IR. Besides, we are the pioneer in revealing that WW had an undifferential anti-IR effect in comparison to regularly active group, with the associations being approved by 6 different IR indices and subgroup analyses. Furthermore, several interaction effect were observed, suggesting the potential existence of subpopulations those are more sensitive to WW in reducing IR risk. Our results suggest that public health strategies should emphasize promoting various forms of LTPA pattern to reduce IR risk and improve overall metabolic health.
Physical activity could be separated into occupational, leisure-time and commuting physical activity, and their benefits may differ [32–34]. Besides, a systematic overview including 17 studies have found that leisure time and occupational physical activity are opposed in their duration and intensity [12]. In other words, adults with light intensity occupational physical activity prefer to choose moderate to vigorous LTPA, vice versa. Meanwhile, multiple studies have found the reduced cardiovascular risk by LTPA higher than occupational physical activity, and in some studies it even did not exist in occupational physical activity [35 36]. A systematic-review and dose-response meta-analysis of 103 prospective cohort studies achieved similar results, in which an inverse dose-response relationship between LTPA and risk of cardiovascular disease, coronary heart disease, stroke, and atrial fibrillation while occupational physical activity showed no benefits in total or any type of cardiovascular disease [37]. As a result of this, we focus on LTPA in this study and further segment LTPA into different LTPA patterns based on duration and freqency.
WW emerged as a response to modern sedentary work environments and busy schedules, gaining popularity through media influence, cultural shifts, and scientific endorsement [38]. It offers a practical solution for those struggling to find time for regular exercise during the week, making it a viable option for maintaining health and fitness in the context of contemporary life. WW prevalence remained stable across 2007–2018 from 5.76% in 2007–2008 and 4.61% in 2017–2018, similar to previous studies [39 40]. Besides, WW prevalence in American adults is higher than that in South Korean, but lower than that in Chinese rural adults [41 42]. However, one significant commonality exist in all studies, which is WW prevalence being significantly higher in men than women.
Although WW increase the risk of shoulder and elbow injuries, the benefits of WW have been investigated by plenty of studies including arterial stiffness, mental disorders and cancer mortality apart from our previous and early mentioned studies [43–47]. Although no studies have evaluated the associations of WW and other LTPA pattern with IR risk, 2 studies have demonstrated the benefits of WW on the risk of metabolic syndrome in South Korean and Chinese rural adults [41 42]. Considered the strong links between IR and metabolic syndrome, we have a belief that their findings support our research results to some content. To further demonstrate the credibility of our results, we conducted stratified analyses and interaction effect, and the results revealed the consistency across demographic groups. Nevertheless, 3 interaction effects were observed in different subgroups and IR indices, which may be just a statistical correlation. Meanwhile, more prospective studies and randomized controlled trails are urgently warranted for further explorations about whether it was just a statistical relationship but not a actual connection or some subpopulations are indeed more susceptible to WW and reach a significant lower IR risk.
In addition, our results exhibited the nonlinear associations of LTPA and IR risked defined by TyG and TyG-BMI. From 150 mins/wk to 360 mins/wk (the median LTPA in WW and regularly active adults), adults had gradually decreased IR risk defined by TyG or TyG-BMI as LTPA increased. Besides, IR risk defined by TyG index decreased continuously as LTPA increased from 360 mins/wk to about 710 mins/wk, and no significant lowering risk was observed when LTPA exceeded 710 mins/wk. As for IR defined by TyG-BMI index, adults exceeding 360 mins/wk LTPA did not exhibit lower IR risk in comparison to the median. Meanwhile, the relationship was similar to that in regularly active adults as demonstrated in Supplemental Fig. 1. All these results indicated that the anti-IR effect of LTPA may have a threshold, which needs to be given priority attention. Understanding the threshold could help in establishing LTPA guidelines and reducing IR and related metabolic disorders.
Plenty of research have emphasized various potential molecular mechanism of LTPA against IR including insulin signaling pathway and chronic inflammation to enhance insulin secretion and skeletal muscle glucose transport, contributing to elevated insulin sensitivity and glucose tolerance [48–52]. Meanwhile, several components such as sestrins, fibronectin and growth differentiation factor 15 were also considered as mediators [53–55]. In our future studies, we would like to conduct a population-based study to explore the comprehensive impact of WW as well as dietary habits in Chinese adults and explore potential mediators based on the huge differences of LTPA pattern, dietary habits and IR prevalence between America and China.
A major strength of this study is the use of a large, nationally representative sample from NHANES, which enhances the generalizability of our findings. Additionally, the comprehensive assessment of IR using multiple indices provides a robust evaluation of metabolic health. The study also controlled for a wide range of potential confounders as well as various statistical analyses, including demographic variables, lifestyle factors, and comorbidities, further strengthening the validity of our results.
However, some limitations should be noted. The reliance on self-reported LTPA data may introduce recall bias and misclassification. Objective measures of physical activity, such as accelerometry, could provide more accurate assessments. Furthermore, the cross-sectional design of NHANES limits our ability to establish causality between LTPA patterns and IR. Longitudinal studies are needed to confirm these associations and to explore the long-term effects of different physical activity patterns on metabolic health.