How fit you are in midlife may help determine not just how long you live, but how many of those years are spent in good health, according to a study published in the JACC, the flagship journal of the American College of Cardiology.

The study found that adults with higher levels of cardiorespiratory fitness in midlife lived longer lives, developed fewer chronic diseases and spent more years free from serious illness compared with those who were less fit.

Cardiorespiratory fitness—how well the heart and lungs supply oxygen during physical activity—is known to reduce the risk of heart disease and early death. This study extends prior research by showing that fitness also plays a meaningful role in healthy aging, defined as years lived without major chronic disease.

The findings indicate that higher fitness in midlife is strongly associated with later onset of chronic disease, lower overall disease burden and longer life expectancy. These benefits were observed in both men and women.

Researchers followed more than 24,500 men and women who were healthy through age 65 and tracked their health outcomes later in life using Medicare data. Fitness was measured earlier in adulthood using a treadmill test, and researchers examined the development of 11 major chronic conditions, including heart disease, diabetes, kidney disease and cancer.

Compared with people who had low fitness levels, those with high fitness in midlife experienced clear benefits later in life. On average, they developed chronic diseases at least 1.5 years later, had fewer total conditions and lived longer overall. These patterns were seen in both men and women and across different ages, body weights and smoking histories.

Importantly, the study emphasizes health span—not just lifespan—highlighting that fitness helps people live more of their lives in good health, not simply live longer with disease.

The findings also underscore the public health value of physical activity, as cardiorespiratory fitness can be improved through regular movement such as brisk walking, cycling or other aerobic exercise.

Researchers note that improving fitness during midlife may be a key strategy for promoting healthy aging and preserving quality of life later on, even with modest increases in physical activity.

Heart failure affects more than 64 million people worldwide (1%–3% in the general adult population) and its prevalence is projected to increase. This condition is commonly categorized into 2 main types: heart failure with reduced ejection fraction (HFrEF; where the heart is too weak to pump enough blood to meet the body’s needs) and heart failure with preserved ejection fraction (HFpEF; where the heart becomes stiff and cannot relax sufficiently to fill with enough blood).

Regardless of type, heart failure is a life-threatening condition characterized by low exercise tolerance, progressive functional decline, reduced health-related quality of life (HRQoL), and a high risk of hospitalizations, morbidity, and mortality. The study led by Tasuku Terada was published in the Journal of Sport and Health Science.

Previous studies have shown that aerobic training and resistance training independently improve aerobic fitness, walking distance, muscle strength, and HRQoL. Some studies have also demonstrated superior benefits of high-intensity interval training (HIIT) on aerobic fitness and cardiac function in patients with heart failure when compared to traditionally used moderate-intensity continuous training.

However, despite the well-established benefits of each exercise modality, the effects of combining aerobic training and muscle strength training (i.e., combined training) compared to the routinely recommended aerobic training alone were not clear in patients with heart failure. In this study, the researchers compared the effects of combined training and aerobic training alone on aerobic fitness, muscle strength, and HRQoL in patients with heart failure. These comparisons were made while accounting for heart failure classifications (i.e., HFrEF or HFpEF), total exercise duration (i.e., matched or unmatched exercise session duration between combined and aerobic training alone), and exercise type (e.g., HIIT). 

The researchers systematically searched databases for studies directly comparing the effects of combined training and aerobic training alone on aerobic fitness, walk test distance, muscle strength, and HRQoL in patients with heart failure. Of 13,965 studies they screened, 15 studies were included (466 patients with HFrEF (89%) and 60 with HFpEF (11%); 17% female).

Pooled analyses showed that, in HFrEF, combined training increased aerobic fitness, walk test distance, and upper body muscle strength more than aerobic training alone. The superior effects of combined training on aerobic fitness and walking distance were retained when exercise session duration was matched between the two exercise modalities, indicating that combined training has a greater impact on these measures independent of total exercise duration. HIIT combined with muscle strength training also increased aerobic fitness more than HIIT alone.

No differences were found between combined and aerobic training alone in lower body muscle strength or HRQoL. Overall adherence to combined training was high or comparable to that of aerobic training alone.

Similarly, dropout rates in the combined training group were comparable to those in aerobic training alone, and no notable differences in the risk of adverse events were observed. 

To summarise, in predominantly male patients with HFrEF, combined training yielded greater improvements in aerobic fitness, walking distance, and upper body muscle strength than aerobic training alone.  These results highlight that, when prescribing exercise for a fixed time frame, allocating time to both aerobic training and muscle strength training may be a more effective strategy for improving aerobic fitness in patients with HFrEF.

Additionally, because HIIT may improve aerobic fitness more effectively while requiring less time than moderate-intensity continuous training, combining HIIT with muscle strength training may offer a time-efficient approach to improve aerobic fitness in patients with HFrEF.

Considering the absence of notable differences in adherence or adverse events, these findings support that replacing part of aerobic training with muscle strength training may be an effective strategy for patients with HFrEF to increase aerobic fitness, walking distance, and muscle strength, all of which are important predictors of better prognosis in patients with heart failure. Further evidence is needed to clarify the effects of combined training in HFpEF.

Regular physical activity and getting the recommended amount of sleep may reduce dementia risk later in life, according to a study by Akinkunle Oye-Somefun and colleagues, published in the open-access journal PLOS One.

An estimated 55 million people live with dementia worldwide, and both its prevalence and cost are expected to increase, with global costs projected to reach $2 trillion dollars by 2030. Current treatments for preventing or treating dementia have limited efficacy; therefore, public health efforts have also aimed at healthy lifestyle factors to reduce the risk of dementia before symptoms occur. Healthy behaviors such as regular physical activity and good sleep hygiene are known to support cognitive health; however, there remains a need to better understand their relationship to dementia.

In this systematic review and meta-analysis, researchers analyzed data from 69 prospective cohort studies representing millions of community-dwelling adults aged 35+, to see if there was a link between the development of dementia and three lifestyle behaviors: physical activity, sedentary behavior, and sleep duration. Each of the observational studies recorded behaviors of cognitively healthy participants, then followed up at a later timepoint to report subsequent rates of dementia.

Overall, the meta-analysis found that regular physical activity, less sedentary time, and appropriate nightly sleep (7–8 h) were associated with a lower subsequent risk of dementia. Regular physical activity was associated with an average 25% lower risk of dementia among the 49 studies analyzed; however, the researchers note that there was considerable heterogeneity between the studies.

Too little sleep (<7 h) or too much sleep (>8 h) was associated with an 18% and 28% higher subsequent risk of dementia, respectively, compared to optimal nightly sleep of 7-8 hours, though there was again considerable heterogeneity among the 17 studies analyzed. Prolonged sitting (>8 hours per day) was associated with a 27% higher risk of dementia among the 3 relevant studies analyzed.

The study is consistent with and expands on previous research, using a large, diverse population with long follow-up times. While the study design cannot show any causative link between physical activity, sleep and dementia, the findings suggest an association between adherence to recommended physical activity and sleep levels in middle- and older-age adults and lowered dementia risk later in life.

The authors add: “Dementia develops over decades, and our findings suggest that everyday behaviours such as physical activity, time spent sitting, and sleep duration may be linked to dementia risk. Understanding how each of these behaviours relates to risk over time may help researchers identify opportunities to support brain health across the life course.”

“Separately, one aspect I personally found most interesting while conducting the study was the relatively limited evidence base on sedentary behaviour. Despite growing recognition that prolonged sitting is distinct from physical inactivity, we found only a small number of cohort studies examining its relationship with dementia risk. This highlights an important gap for future research.”