The combination of cardiorespiratory fitness and muscle strength, and mortality risk

Prognostic Relevance of Cardiorespiratory Fitness as Assessed by Submaximal Exercise Testing for All-Cause Mortality: A UK Biobank Prospective Study

OBJECTIVE

To investigate whether the inverse associations of cardiorespiratory fitness (CRF) with all-cause and cardiovascular mortality in the general population vary among individuals who are at different levels of pretest risk.

PATIENTS AND METHODS

Cardiorespiratory fitness was assessed through submaximal bicycle tests in 58,892 participants aged 40 to 69 years who completed baseline questionnaires between January 1, 2006, and December 31, 2010, in the UK Biobank Prospective Study. Participants were categorized into risk categories, which determined allocation to an individualized bicycle protocol. The groups at minimal risk (category 1), small risk (category 2), and medium risk (category 3) were tested at 50%, 35% of the predicted maximal workload, and constant level, respectively. We investigated associations of CRF with mortality across different levels of pretest risk and determined whether CRF improves risk prediction.

RESULTS

During a median follow-up of 5.8 years, 936 deaths occurred. Cardiorespiratory fitness was linearly associated with mortality risk. Comparing extreme fifths of CRF, the multivariable-adjusted hazard ratios (95% CIs) for mortality were 0.63 (0.52-0.77), 0.54 (0.36-0.82), 0.81 (0.46-1.43), and 0.58 (0.48-0.69) in categories 1, 2, and 3 and overall population, respectively. The addition of CRF to a 5-year mortality risk score containing established risk factors was associated with a C-index change (0.0012; P=.49), integrated discrimination improvement (0.0005; P<.001), net reclassification improvement (+0.0361; P=.005), and improved goodness of fit (likelihood ratio test, P<.001). Differences in 5-year survival were more pronounced across levels of age, smoking status, and sex.

CONCLUSION

Cardiorespiratory fitness, assessed by submaximal exercise testing, improves mortality risk prediction beyond conventional risk factors and its prognostic relevance varies across cardiovascular risk levels.

[Measuring physical fitness in the German National Cohort-methods, quality assurance, and first descriptive results]

Physical fitness is defined as an individual's ability to be physically active. The main components are cardiorespiratory fitness (CRF), muscle strength, and flexibility. Regardless of physical activity level, physical fitness is an important determinant of morbidity and mortality.The aim of the current study was to describe the physical fitness assessment methodology in the German National Cohort (NAKO) and to present initial descriptive results in a subsample of the cohort.In the NAKO, hand grip strength (GS) and CRF as physical fitness components were assessed at baseline using a hand dynamometer and a submaximal bicycle ergometer test, respectively. Maximum oxygen uptake (VO_2max) was estimated as a result of the bicycle ergometer test. The results of a total of 99,068 GS measurements and 3094 CRF measurements are based on a data set at halftime of the NAKO baseline survey (age 20-73 years, 47% men).Males showed higher values of physical fitness compared to women (males: GS = 47.8 kg, VO_2max = 36.4 ml·min^-1 · kg^-1; females: GS = 29.9 kg, VO_2max = 32.3 ml · min^-1 · kg^-1). GS declined from the age of 50 onwards, whereas VO_2max levels decreased continuously between the age groups of 20-29 and ≥60 years. GS and VO_2max showed a linear positive association after adjustment for body weight (males β = 0.21; females β = 0.35).These results indicate that the physical fitness measured in the NAKO are comparable to other population-based studies. Future analyses in this study will focus on examining the independent relations of GS and CRF with risk of morbidity and mortality.

The effects of same-session combined exercise training on cardiorespiratory and functional fitness in older adults: a systematic review and meta-analysis

Endurance and strength training are effective strategies for counteracting age-associated reductions in physical performance in older adults, with a combination of both exercise modes recommended to maximise potential fitness benefits. This meta-analysis sought to quantify the effects of same-session combined endurance and strength training on fitness in adults aged over 50 years. Five electronic databases were searched with studies required to include one of the following outcome measures: VO_2peak, 6-min walk test (6MWT), 8-ft timed up-and-go (TUG), and 30-s chair stand. Separate random-effects meta-analyses compared combined training with (1) no-exercise control, (2) endurance training, and (3) strength training with probabilistic magnitude-based inferences subsequently applied. Twenty-seven studies involving 1346 subjects with a mean age of 68.8 years (range 54–85 years) were included in the analysis. The meta-analysed effect on VO_2peak was a moderately beneficial effect for the combined training compared to no-exercise controls (3.6 mL kg⁻¹ min⁻¹; ± 95% confidence limits 0.8 mL kg⁻¹ min⁻¹) with additional increases for studies with greater proportions of female participants and shorter training interventions. Combined training also had small-to-moderately beneficial effects on VO_2peak when compared to endurance training (0.8 mL kg⁻¹ min⁻¹; ± 1.0 mL kg⁻¹ min⁻¹), 30-s chair stand when compared with strength training (1.1 repetitions; ± 0.5 repetitions) and on TUG (0.8 s; ± 0.7 s), 30-s chair stand (2.8 repetitions; ± 1.7 repetitions), and 6MWT (31.5 m; ± 22.4 m) when compared to no-exercise controls. All other comparisons were unclear. Same-session combined training can induce clinically relevant fitness improvements in older adults.

Grip Strength: An Indispensable Biomarker For Older Adults

Grip strength has been proposed as a biomarker. Supporting this proposition, evidence is provided herein that shows grip strength is largely consistent as an explanator of concurrent overall strength, upper limb function, bone mineral density, fractures, falls, malnutrition, cognitive impairment, depression, sleep problems, diabetes, multimorbidity, and quality of life. Evidence is also provided for a predictive link between grip strength and all-cause and disease-specific mortality, future function, bone mineral density, fractures, cognition and depression, and problems associated with hospitalization. Consequently, the routine use of grip strength can be recommended as a stand-alone measurement or as a component of a small battery of measurements for identifying older adults at risk of poor health status.

An Update on the Role of Cardiorespiratory Fitness, Structured Exercise and Lifestyle Physical Activity in Preventing Cardiovascular Disease and Health Risk

The cardiovascular disease (CVD) pandemic has placed considerable strain on healthcare systems, quality of life, and physical function, while remaining the leading cause of death globally. Decades of scientific investigations have fortified the protective effects of cardiorespiratory fitness (CRF), exercise training, and physical activity (PA) against the development of CVD. This review will summarize recent efforts that have made significant strides in; 1) the application of novel analytic techniques to increase the predictive utility of CRF; 2) understanding the protective effects of long-term compliance to PA recommendations through large cohort studies with multiple points of assessment; 3) and understanding the potential harms associated with extreme volumes of PA.

Fitness versus adiposity in cardiovascular disease risk

Obesity and low cardiorespiratory fitness are both established predictors of cardiovascular disease morbidity and mortality. Whether the protective effects of fitness outweigh the deleterious effects of obesity, however, remains a topic of debate. To extend knowledge of the relative influence of fitness and fatness on cardiovascular disease outcomes, however, attention must be paid to measurement quality. Eliminating inherent bias of self-report and including the highest quality assessments of cardiorespiratory fitness and fatness simultaneously are imperative for head-to-head comparisons. Studies must move beyond body mass index and total body fat percentage to differentiate the heterogenous effects of various adipose tissue depots on cardiovascular risk. Imaging techniques that measure visceral adiposity and other risk-laden ectopic adipose depots while also quantifying cardioprotective adipose depots such as lower body subcutaneous fat and even non-adipose tissues such as skeletal muscle may further illuminate the influence of body composition on cardiovascular health. This review underscores key studies within a large body of literature that provide the foundation for the fit-vs.-fat debate in the context of cardiovascular disease risk, and identifies important considerations for future research.