What is new in this BASRaT issue?

The 2020 WHO Guidelines on physical activity and sedentary behaviour2 are a comprehensive set of public health recommendations that form an essential part of our practice as clinicians. The evidence base for the recommendations is continuing to grow and several key gaps in our knowledge will be discussed in this issue of the BJSM.

Cardiorespiratory fitness, weight loss and sleep

What is the predictive value of cardiorespiratory fitness (CRF) and can it be comparable with commonly used risk scores like Framingham? In the first meta-analysis to quantify the association of CRF with cardiovascular disease (CVD) and cancer mortality, Minghui Han and colleagues from Zhengzhou and Shenzhen Universities in the People’s Republic of China seek to provide answers to these important questions ( see page 733 ). The authors also generate useful discussion and links to earlier research about using estimated instead of directly measured CRF.3

One topic of conversation that frequently arises with patients is the relationship between weight loss and exercise, a highly nuanced topic that probably needs to be reframed to reflect the complex interactions between these factors. In a harmonised meta-analysis, Dr Jakob Tarp from the Norwegian School of Sports Sciences and a big hitting team of researchers from across the globe look at the relationships between adiposity, device-measured physical activity (PA) and mortality ( see page 725 ). They offer some key insights about the importance of PA promotion regardless of weight status and the survival benefit with different combinations of adiposity and activity levels. In a similar theme, a discussion piece by Dr Stuart Phillips and colleagues from McMaster University delves into the science and rationale underpinning exercise, long-term metabolic health and the importance of lean muscle mass for the maintenance of weight loss ( see page 771 ).

When we consider our daily cycle and maximising positive health outcomes, we often consider sleep as important, but we do not necessarily understand its specific associations with sedentary behaviour and PA. Can lower PA levels amplify the negative implications of poor sleep and can higher levels of PA offset them? In a novel prospective study, Bo-Huei Huang and prominent researchers from Australia and London seek to answer these questions and provide an insight into the interactions between sleep and PA in relation to all-cause, total CVD and cancer mortality ( see page 718 ).

Muscle matters

Although muscle strengthening activities are included in both national and international PA recommendations, they are frequently deemed a lot less important from a mortality perspective than aerobic exercise. In an exciting systematic review and meta-analysis, Drs Haruki Momma and Ryoko Kawakami’s team from Japan set out to define the independent association of resistance training (RT) with the risk of CVD, total cancer, diabetes, lung cancer and all-cause mortality ( see page 755 ). This paper should provide valuable knowledge to underpin the rationale for RT exercise prescription above and beyond improving physical function and maintaining lean muscle mass.

Other must-reads in this issue include the safety of maximal exercise testing in individuals with sickle cell disease, the effects of before-school PA programmes on children’s PA levels, health and learning and a set piece approach to emergency action planning for managing emergencies in sport. We also have a patient voice from a young athlete and an inspiring service spotlight with a call for volunteers. Here is to collaborative working and improving global health!