Regular Running Is Related to the Knee Joint Cartilage Structure in Healthy Adults.

PURPOSE: The purpose of this study was to determine whether regular running distance and biomechanics are related to medial central femur cartilage (MCFC) structure. METHODS: The cross-sectional study sample consisted of 1164 runners and nonrunners aged 18-65 yr. Participants completed questionnaires on physical activity and their running history. We performed quantitative magnetic resonance imaging of knee cartilage-T2 relaxation time (T2) mapping (high T2 indicates cartilage degeneration)-and a running biomechanical analysis using a three-dimensional motion capture system. A 14-d monitoring of the physical activity was conducted. RESULTS: Those aged 35-49 yr were at 84% higher odds of having MCFC T2 in the highest level (85th percentile, P < 0.05) compared with youngest adults indicating that MCFC structures may be altered with aging. Being male was associated with 34% lower odds of having T2 at the highest level ( P < 0.05) compared with females. Nonrunners and runners with the highest weekly running distance were more likely to have a high T2 compared with runners with running distance of 6-20 km·wk -1 ( P < 0.05). In addition, the maximal knee internal adduction moment was associated with a 19% lower odds of having T2 at the highest level ( P < 0.05). CONCLUSIONS: Females compared with males and a middle-aged cohort compared with the younger cohort seemed to be associated with the degeneration of MCFC structures. Runners who ran 6-20 km·wk -1 were associated with a higher quality of their MCFC compared with highly active individuals and nonrunners. Knee frontal plane biomechanics was related to MCFC structure indicating a possibility of modifying the medial knee collagen fibril network through regular running.

A two-week course of transcutaneous vagal nerve stimulation improves global sleep: Findings from a randomised trial in community-dwelling adults.

Short sleep duration and poor sleep quality are common in the general population. This study tested if a 2-week course of daily transcutaneous vagal nerve stimulation (tVNS) improves sleep in community-dwelling adults. Participants were n = 68 men and women aged 18-75 years randomised into four groups: early and sham tVNS and late and sham tVNS. Early groups underwent daily 4 h stimulation between Day 0 and 13, while late groups underwent daily 4 h stimulation between Day 14 and 28. tVNS was performed with transcutaneous electrical nerve stimulation (TENS) on the left tragus, and sham tVNS (control conditions) was applied on the left earlobe. Sleep was measured with the Pittsburgh Sleep Quality Index. Analysis of prespecified contrasts (C), based on linear mixed modelling, revealed that for tVNS there were significant improvements in global sleep scores over time between Day 0 and Day 13 in the early stimulation phase (C = -1.90; 95% CI = -2.87 to -0.94), and between Day 14 and Day 28 in the late phase (C = -0.87; 95% CI = -1.41 to -0.32). No such differences were found under sham tVNS (applied early or late). However, global sleep scores showed no significant improvement under tVNS when compared against control groups during both the early (χ2 = 0.83, p = 0.36), or late stimulation phase (χ2 = 0.24, p = 0.63). We showed that two weeks of tVNS improves global sleep scores, but the change in sleep was not significantly different to control groups. Further studies are warranted to test the utility of tVNS in alleviating sleep complains in community-dwelling adults.

Healthy Lifestyle and Cardiac Vagal Modulation Over 10 Years: Whitehall II Cohort Study.

Background Increased vagal modulation is a mechanism that may partially explain the protective effect of healthy lifestyles. However, it is unclear how healthy lifestyles relate to vagal regulation longitudinally. We prospectively examined associations between a comprehensive measure of 4 important lifestyle factors and vagal modulation, indexed by heart rate variability (HRV) over 10 years. Methods and Results The fifth (1997-1999), seventh (2002-2004), and ninth (2007-2009) phases of the UK Whitehall II cohort were analyzed. Analytical samples ranged from 2059 to 3333 (mean age: 55.7 years). A healthy lifestyle score was derived by giving participants 1 point for each healthy factor: physically active, not smoking, moderate alcohol consumption, and healthy body mass index. Two vagally mediated HRV measures were used: high-frequency HRV and root mean square of successive differences of normal-to-normal R-R intervals. Cross-sectionally, a positively graded association was observed between the healthy lifestyle score and HRV at baseline (Poverall≤0.001). Differences in HRV according to the healthy lifestyle score remained relatively stable over time. Compared with participants who hardly ever adhered to healthy lifestyles, those with consistent healthy lifestyles displayed higher high-frequency HRV (ß=0.23; 95% CI, 0.10-0.35; P=0.001) and higher root mean square of successive differences of normal-to-normal R-R intervals (ß=0.15; 95% CI, 0.07-0.22; P≤0.001) at follow-up after covariate adjustment. These differences in high-frequency HRV and root mean square of successive differences of normal-to-normal R-R intervals are equivalent to ≈6 to 20 years differences in chronological age. Compared with participants who reduced their healthy lifestyle scores, those with stable scores displayed higher subsequent high-frequency HRV (ß=0.24; 95% CI, 0.01-0.48; P=0.046) and higher root mean square of successive differences of normal-to-normal R-R intervals (ß=0.15; 95% CI, 0.01-0.29; P=0.042). Conclusions Maintaining healthy lifestyles is positively associated with cardiac vagal functioning, and these beneficial adaptations may be lost if not sustained.

Potential biological pathways linking Type-D personality and poor health: A cross-sectional investigation.

BACKGROUND: Type-D personality, defined as a combination of high negative affect and high social isolation, has been associated with poor health outcomes. However, pathways underlying this association are largely unknown. We investigated the relationship between Type-D personality and several biological and behavioral pathways including the autonomic nervous system, the immune system, glucose regulation and sleep in a large, apparently healthy sample. METHODS: Data from a total of 646 respondents (age 41.6±11.5, 12,2% women) were available for analysis. Persons with Type-D (negative affect and social isolation score ≥10) were contrasted with those without Type-D. Measures of plasma fibrinogen levels, white blood cell count, high sensitivity C-reactive protein, fasting plasma glucose (FPG), cholesterol, high-density and low-density lipoprotein, glycated hemoglobin (HbA1c), creatinine, triglycerides, and albumin were derived from fasting blood samples. Urine norepinephrine and free cortisol were determined by high-performance liquid chromatography. Time-domain heart rate variability (HRV) measures were calculated for the 24hr recording period and for nighttime separately. RESULTS: Persons with Type-D had higher HbA1c, FPG, and fibrinogen, and lower nighttime HRV than those without Type-D, suggesting worse glycemic control, systemic inflammation and poorer autonomic nervous system modulation in Type-D persons. In addition, those with Type-D reported less social support and greater sleep difficulties while no group differences were observed for alcohol and cigarette consumption, physical activity and body mass index. CONCLUSIONS: Findings provide some of the first evidence for multiple possible biological and behavioral pathways between Type-D personality and increased morbidity and mortality.

Are Changes in Heart Rate Variability in Middle-Aged and Older People Normative or Caused by Pathological Conditions? Findings From a Large Population-Based Longitudinal Cohort Study.

BACKGROUND: No study to date has investigated longitudinal trajectories of cardiac autonomic modulation changes with aging; therefore, we lack evidence showing whether these changes occur naturally or are secondary to disease or medication use. This study tested whether heart rate variability (HRV) trajectories from middle to older age are largely normative or caused by pathological changes with aging in a large prospective cohort. We further assessed whether HRV changes were modified by socioeconomic status, ethnicity, or habitual physical activity. METHODS AND RESULTS: This study involved 3176 men and 1238 women initially aged 44 to 69 years (1997-1999) from the UK Whitehall II population-based cohort. We evaluated time- and frequency-domain HRV measures of short-term recordings at 3 time points over a 10-year period. Random mixed models with time-varying covariates were applied. Cross-sectionally, HRV measures were lower for men than for women, for participants with cardiometabolic conditions, and for participants reporting use of medications other than beta blockers. Longitudinally, HRV measures decreased significantly with aging in both sexes, with faster decline in younger age groups. HRV trajectories were not explained by increased prevalence of cardiometabolic problems and/or medication use. In women, cardiometabolic problems were associated with faster decline in the standard deviation of all intervals between R waves with normal-to-normal conduction, in low-frequency HRV, and in low-frequency HRV in normalized units. Socioeconomic status, ethnicity, and habitual physical activity did not have significant effects on HRV trajectories. CONCLUSIONS: Our investigation showed a general pattern and timing of changes in indices of cardiac autonomic modulation from middle to older age. These changes seem likely to reflect the normal aging process rather than being secondary to cardiometabolic problems and medication use.

The impact of unemployment on heart rate variability: the evidence from the Czech Republic.

We examined the relationship between unemployment and heart rate variability (HRV) in a region of high unemployment in the Czech Republic. The study involved 21 involuntarily unemployed and 21 employed men and women aged 30-49 years, matched on number of potentially confounding factors, including age, gender, type of job, health related behavior and body mass index. HRV was assessed in response to a modified orthostatic test. Compared with the employed group, unemployed participants had decreased high frequency HRV (p=0.018), lower root mean square of successive differences (p=0.050), and lower total spectral variability (p=0.022). These findings suggest that unemployment is a potential chronic stressor that may lead to suppression of vagal activity. This may be one mechanism linking unemployment with cardiovascular disease risk.