The cardiovascular risks of physical activity

Association between accelerometer-derived physical activity and incident cardiac arrest

AIMS

Studies on objectively measured physical activity (PA) have investigated acute cardiovascular outcomes but not cardiac arrest (CA). Our study aimed to investigate the dose-response relationship between accelerometer-measured PA and CA by intensity of PA.

METHODS AND RESULTS

This prospective cohort study included 98 893 UK Biobank participants whose PA data were measured using wrist-worn accelerometers. Total PA volume was measured using the average overall acceleration. Minutes per week of light PA (LPA), moderate PA (MPA), and vigorous PA (VPA) were recorded. The incident CA was identified using diagnostic codes linked to hospital encounters and death records. Cox proportional hazard models with restricted cubic splines were used to study the associations, including sex differences. During the follow-up period (median: 7.31 years; interquartile range: 6.78-7.82 years), 282 incident CAs (0.39 per 1000 person-years) occurred. Total PA was inversely related to CA risk. The CA risk decreased sharply until the time spent in MPA or VPA reached ∼360 min or 20 min per week, respectively, after which it was relatively flat. The LPA was not associated with CA risk. Subgroup analyses showed a more pronounced association between PA and a reduced risk of CA in women compared to men.

CONCLUSION

Accelerometer-measured PA, particularly MPA and VPA, was associated with a lower CA risk. Furthermore, a stronger association was observed in women than men.

Sudden cardiac arrest during sports activity in middle age

BACKGROUND

Sports-associated sudden cardiac arrests (SCAs) occur mostly during middle age. We sought to determine the burden, characteristics, and outcomes of SCA during sports among middle-aged residents of a large US community.

METHODS AND RESULTS

Patients with SCA who were 35 to 65 years of age were identified in a large, prospective, population-based study (2002-2013), with systematic and comprehensive assessment of their lifetime medical history. Of the 1247 SCA cases, 63 (5%) occurred during sports activities at a mean age of 51.1±8.8 years, yielding an incidence of 21.7 (95% confidence interval, 8.1-35.4) per 1 million per year. The incidence varied significantly by sex, with a higher incidence among men (relative risk, 18.68; 95% confidence interval, 2.50-139.56) for sports SCAs compared with all other SCAs (relative risk 2.58; 95% confidence interval, 2.12-3.13). Sports SCA was also more likely to be a witnessed event (87% versus 53%; P<0.001) with cardiopulmonary resuscitation (44% versus 25%; P=0.001) and ventricular fibrillation (84% versus 51%; P<0.0001). Survival to hospital discharge was higher for sports-associated SCA (23.2% versus 13.6%; P=0.04). Sports SCA cases presented with known preexisting cardiac disease in 16% and ≥1 cardiovascular risk factors in 56%, and overall, 36% of cases had typical cardiovascular symptoms during the week preceding the SCA.

CONCLUSIONS

Sports-associated SCA in middle age represents a relatively small proportion of the overall SCA burden, reinforcing the idea of the high-benefit, low-risk nature of sports activity. Especially in light of current population aging trends, our findings emphasize that targeted education could maximize both safety and acceptance of sports activity in the older athlete.

[Exercise in migraine treatment. Review and discussion of clinical trials and implications for further trials]

Regular exercise is recommended in general treatment guidelines for migraine. However, scientific evidence in support of this recommendation is weak. The majority of available trials on this topic do not meet modern requirements for randomized clinical trials. Often the diagnosis of migraine is not certain, the duration of treatment is too short, and the intervention is not clearly defined; furthermore, the control of treatment is insufficient. The study results are controversial regarding the efficiency of sports intervention in migraine. Regular exercises may have specific effects on the course of disease in migraine through increase of fitness or relaxing effects. It remains unclear whether exercise alone is efficient in migraine treatment or only as part of a more multidisciplinary program. Theoretical considerations, the available limited studies, and clinical experience suggest that exercise may have an effect on migraine, but the present knowledge does not fulfill the needs of evidence-based medicine. Future studies should adhere to the rules for randomized clinical trials in pharmacological migraine prophylaxis.

Electrocardiographic responses to jogging in middle-aged and older men and women

Recent jogging-related sudden deaths rekindled the concern among health professionals as to the hazards of strenuous exercise. The purpose of this study was to evaluate the extent of rhythm disturbances and myocardial ischemia in older men and women during a typical strenuous jogging session. Twenty-two members of a local jogging club (11 men and 11 women) between the ages of 50 and 66 years participated in the study. The CardioData PR3/ST monitor was employed to record heart rate, rhythm disturbances, J point and ST slope during the course of the run. The men ran a 10 km run and the women a 6 km run at a competitive pace. The mean maximal heart rate during the run was 170 +/- 15 beats/min for the males and 176 +/- 14 beats/min for the females. The mean J point during the run was -3.39 +/- 1.21 mV for the males and -2.97 +/- 0.96 mV for the females. Females showed a significantly lower mean ST slope (3.95 +/- 0.91 mV) during the run than the males (5.56 +/- 1.37 mV, p < 0.05). A number of episodes of premature ventricular beats, both uni- and multifocal, were observed. Exercise testing of sufficient intensity is recommended to detect those persons susceptible to developing serious arrhythmias during strenuous exercise.

Biphasic changes in leukocytes induced by strenuous exercise

Seven healthy male volunteers participated in short- (STR, 1.7 km), middle- (MTR, 4.8 km) and long- (LTR, 10.5 km) term runs at a speed close to their maximum. A prompt mobilization of white cells, and lymphocytes in particular, appeared following the exercise. The initial increase in the number of lymphocytes was succeeded by a significant decrease [(P less than 0.03) lymphopenial], which on average was 32%-39% of the pre-exercise values in all groups. A close correlation was found between the initial increase in plasma cortisol concentration after exercise and the subsequent lymphopenia. A modest enhancement in the number of granulocytes immediately after the exercise was accompanied by a comprehensive increase in polymorphonuclear (PMN) elastase concentration accounting for 78.6%, SEM 16.3%, 140.7%, SEM 31.8% and 241.3%, SEM 48.1% in the STR, MTR and LTR groups. No correlation was found between granulocyte number and the plasma PMN elastase concentration. A delayed granulocytosis was noted in all subjects, reaching a peak between 2 and 4 h after the exercise. The magnitude of the granulocytosis varied among subjects and peak values of the number of circulating granulocytes were found to be 5.7 x 10(9) cells.l-1, SEM 0.5, 6.7 x 10(9) cells.l-1, SEM 0.6 and 8.8 x 10(9) cells.l-1, SEM 0.5 in STR, MTR and LTR respectively, whereas the mean baseline value was 3.6 x 10(9) cells.l-1, SEM 0.4. The neutrophilic granulocytosis was not accompanied by a corresponding enhancement in PMN elastase concentration. The plasma cortisol concentration reached a peak 30 min after exercise and declined below the control level in 4 h. Neither the initial increase, nor the subsequent decrease in plasma cortisol concentration were found to be essential for the magnitude of the delayed leukocytosis.