Objective: Investigate associations between pre-pregnancy participation and performance in a demanding cross-country ski race (proxy for exercise volume and fitness) and perinatal outcomes. Pre-registered protocol: osf.io/aywg2.Design: Prospective cohort study.Setting: Based on entire overlap between the Vasaloppet registry and the population-based Swedish Pregnancy Register.Sample: All female Vasaloppet participants 1991-2017 with subsequent singleton delivery (skiers), and age- and county-matched non-skiers.Methods: We calculated odds ratios (ORs) for non-skiers versus skiers (model 1) and, among skiers, by performance (model 2), in Bayesian logistic regressions adjusted for socio-demographics, lifestyle factors, and comorbidities. We repeated calculations adjusting for early pregnancy body mass index (potential mediator) and explored robustness (selection/exposure settings; multiple comparisons correction).Main outcome measures: Twenty-nine important perinatal outcomes, predefined based on existing expert consensus.Results: Non-skiers (n = 194 384) versus skiers (n = 15 377) (and slower versus faster performance, not shown) consistently had higher odds of gestational diabetes mellitus (GDM) (OR 1.70, 95% highest density interval: 1.40-2.09), excessive gestational weight gain (GWG) (1.28, 1.22-1.38), psychiatric morbidity (1.60, 1.49-1.72), any caesarean section (CS) (1.34, 1.28-1.40), elective CS (1.39, 1.29-1.49), and large-for-gestational-age babies (> 90th percentile, 1.11, 1.04-1.18); lower odds of inadequate GWG (0.83, 0.79-0.88); and no associations with fetal/neonatal complications (e.g. preterm birth [1.09, 0.98-1.20], small for gestational age [SGA] [1.23, 1.05-1.45]). Adjustment for body mass index attenuated associations with excessive (1.20, 1.14-1.30) and inadequate GWG (0.87, 0.83-0.92) and large for gestational age (1.07, 1.00-1.13).Conclusion: Non-skiers compared with skiers, and slower versus faster performance, consistently displayed higher odds of GDM, excessive GWG, psychiatric morbidity, CS and large-for-gestational-age babies; and lower odds of inadequate GWG, after adjustment for socio-demographic and lifestyle factors and comorbidities. There were no associations with fetal/neonatal complications.

Physical activity may prevent anxiety, but the importance of exercise intensity, sex-specific mechanisms, and duration of the effects remains largely unknown. We used an observational study design to follow 395,369 individuals for up to 21 years to investigate if participation in an ultralong-distance cross-country ski race (Vasaloppet, up to 90 km) was associated with a lower risk of developing anxiety. Skiers in the race and matched non-skiers from the general population were studied after participation in the race using the Swedish population and patient registries. Skiers (n = 197,685, median age 36 years, 38% women) had a significantly lower risk of developing anxiety during the follow-up compared to non-skiers (adjusted hazard ratio, HR 0.42). However, among women, higher physical performance (measured as the finishing time to complete the race, a proxy for higher exercise dose) was associated with an increased risk of anxiety compared to slower skiing women (HR 2.00). For men, the finishing time of the race did not significantly impact the risk of anxiety. Our results support the recommendations of engaging in physical activity to decrease the risk of anxiety in both men and women. The impact of physical performance level on the risk of anxiety requires further investigations among women.

Background: Physical activity is associated with reduced risk of Parkinson's disease (PD). The explanations for this association are not completely elucidated. We use long-term PD-incidence data from long-distance skiers to study the relationship between exercise and PD. Objective: We aimed to investigate if physical activity is associated with long-term lower risk of PD and if this association could be explained by physically active people being able to sustain more PD neuropathology before clinical symptoms, a motor reserve. Methods: Using a prospective observational design, we studied whether long-distance skiers of the Swedish Vasaloppet (n = 197,685), exhibited reduced incidence of PD compared to matched individuals from the general population (n = 197,684) during 21 years of follow-up (median 10, interquartile range (IQR) 5-15 years). Results: Vasaloppet skiers (median age 36.0 years [IQR 29.0-46.0], 38% women) had lower incidence of PD (HR: 0.71; 95 % CI 0.56-0.90) compared to non-skiers. When reducing risk for reverse causation by excluding PD cases within the first five years from race participation, there was still a trend for lower risk of PD (HR: 0.80; 95 % CI 0.62-1.03). Further, the PD prevalence converged between skiers and non-skiers after 15 years of follow-up, which is more consistent with a motor reserve in the physically active rather than neuroprotection. Conclusions: A physical active lifestyle is associated with reduced risk for PD. This association weakens with time and might be explained by a motor reserve among the physically active.

Objective: To examine how physical activity is associated with risk of different fracture outcomes across the full range of physical activity. Methods: By combining information from three cohort studies and using generalized structural equation modelling, we estimated a continuous unitless latent variable reflecting physical activity that ranged from sedentary through elite athlete levels. Associations between physical activity and fracture outcomes were assessed with proportional hazards regression using restricted cubic splines with the mean physical activity (corresponding to 20-40 min walking or bicycling/day or 2-3 h exercise/week) as reference. Results: Among 63,980 men and women (49-68 years) and during 13 years of follow-up, 8506 fractures occurred, including 2164 distal forearm, 779 proximal humerus, 346 clinical spine, and 908 hip fractures. Both lower and higher physical activity was associated with higher risk of any fracture compared to the mean. Physical activity at 1 standard deviation (SD) below the mean, corresponding to walking/bicycling <20 min/day or exercising <1-1 h/week, was associated with a lower risk of distal forearm fracture (hazard ratio [HR]: 0.92, 95% confidence interval [CI]: 0.85-0.99) and higher risk of hip fracture (HR: 1.24, 95% CI: 1.13-1.37), but no associations were seen above the mean physical activity level for these fractures. Physical activity was not associated with proximal humerus fracture but had a possible U-shaped association with clinical spine fracture. Conclusion: Physical activity was non-linearly associated with fracture risk and the association differed across fracture sites. Up to 2-3 h weekly exercise is beneficial for the prevention of hip fracture but may increase the risk of distal forearm fracture.

Background: Hypertension is the leading risk factor for death worldwide, and high levels of physical activity are associated with a lower incidence of hypertension. The associations of excessive levels of exercise and incidence of hypertension are less well known. We aim to compare the incidence of hypertension among 206 889 participants in a long-distance cross-country skiing event and 505 542 people randomly sampled from the general population (matched to the skiers on age, sex, and place of residence). Methods: Skiers' best performance (in percent of winning time) and number of completed races during the study period were associated with incidence of hypertension after participation in Vasaloppet. Hypertension was defined as prescription of blood pressure-lowering drugs as obtained from the national drug registry. Models were adjusted for sex, age, education, and income (total effect). Results: During a median time of risk of 8.3 years, skiers had a lower incidence of hypertension compared with nonskiers (hazard ratio [HR], 0.59 [95% CI, 0.58-0.60]). Among the skiers, better performance (in percent of winning time) in Vasaloppet was strongly associated with a lower incidence of hypertension (fastest fifth: HR, 0.41 [95% CI, 0.39-0.42]; slowest fifth: HR, 0.78 [95% CI, 0.75-0.81]). The association was nearly linear and did not differ between sexes. Among the skiers, a weaker association was seen between the number of completed races during the study period and the incidence of hypertension (1 race: HR, 0.63 [95% CI, 0.62-0.65]; >5 races: HR, 0.51 [95% CI, 0.50-0.53]). A subanalysis of 10 804 participants including adjustment for lifestyle factors showed similar results. Conclusions: Participation in a long-distance skiing event was associated with a 41% lower incidence of hypertension over the next 8 years compared with nonparticipation. A near linear association between performance and incidence of hypertension was observed. This adds to the list of beneficial effects of intensive training, because hypertension is the leading risk factor of premature death globally.

Abstract Background/Introduction Aneurysmal dilatation and dissection of the aorta are two facets of aortic disease that can lead to major disability and death. Some risk factors for aortic disease are also risk factors for atherosclerotic disease, but the overall causes of aortic disease are diverse and largely unknown. Persons with aortic aneurysms are advised to limit their physical activity, but associations of physical activity with subsequent incidence of aortic disease are little known. Earlier studies have shown strong association of performance in Vasaloppet with incidence of hypertension, a major risk factor for aortic disease. Aim To investigate associations of high levels of physical activity with incidence of aortic disease. Methods We studied 209,226 participants in a 30–90 km cross-country skiing event (Vasaloppet) and 536,038 persons from the general population, matched to the skiers on age, sex and residence. The number of completed races during the study period and the fastest relative finishing time in a race was recorded. The main outcomes were: 1) aortic disease (defined as thoracic and abdominal aortic aneurysm and/or aortic dissection); and 2) aortic dissection. Results During a median time at risk of 8.8 years, 1,442 aortic disease events and 265 aortic dissections occurred. Skiers had lower incidence of aortic disease than non-skiers (Cox proportional hazards ratio [HR] 0.42; 95% confidence interval [CI] 0.36–0.50). An association of better finishing time with aortic disease was observed, with a dose-response gradient from the fastest third (HR 0.25; 95% CI 0.18–0.35), via the slowest third (HR 0.64; 95% CI 0.49–0.82) to the non-skiers (reference group). Among skiers the number of completed races was not associated with incidence of aortic disease. Skiers also had lower incidence of acute aortic dissection (HR 0.61; 95% CI 0.44–0.85) than non-skiers. Low event rate among skiers made conclusions in subgroups unreasonable. All results are adjusted for age, sex, education and income. Results were similar in models accounting for use of antihypertensive and cholesterol-lowering medicines and genetic syndromes associated with aortic disease. Conclusion Participation in a long-distance skiing event was associated with lower risk of aortic disease and aortic dissection. Faster completion of the race was strongly associated with lower incidence of aortic disease. If causal, this study suggests that high physical activity and exercise may be protective against aortic disease. Kaplan-Meier Aorta disease Funding Acknowledgement Type of funding source: None

Background: Studies have revealed a higher incidence of atrial fibrillation among well-trained athletes. We aim to investigate associations of endurance training with incidence of atrial fibrillation and stroke and to establish potential sex differences of such associations in a cohort of endurance trained athletes. Methods: All Swedish skiers (208 654) completing 1 or more races in the 30 to 90 km cross-country skiing event Vasaloppet (1989-2011) and a matched sample (n=527 448) of nonskiers were followed until first event of atrial fibrillation or stroke. Cox regression was used to investigate associations of number of completed races and finishing time with incidence of atrial fibrillation and stroke. Results: Female skiers in Vasaloppet had a lower incidence of atrial fibrillation than did female nonskiers (hazard ratio [HR], 0.55; 95% CI, 0.48-0.64), independent of finishing time and number of races. Male skiers had a similar incidence to that of nonskiers (HR, 0.98; 95% CI, 0.93-1.03). Skiers with the highest number of races or fastest finishing times had the highest incidence. Skiers of either sex had a lower incidence of stroke than did nonskiers (HR, 0.64; 95% CI, 0.60-0.67), independent of the number of races and finishing time. Skiers with atrial fibrillation had higher incidence of stroke than did skiers and nonskiers without atrial fibrillation (men: HR, 2.28; 95% CI, 1.93-2.70; women: HR, 3.51; 95% CI, 2.17-5.68; skiers with atrial fibrillation vs. skiers without atrial fibrillation). After diagnosis of atrial fibrillation, skiers with atrial fibrillation had a lower incidence of stroke (HR, 0.73; 95% CI, 0.50-0.91) and lower mortality compared with nonskiers with atrial fibrillation (HR, 0.57; 95% CI, 0.49-0.65). Conclusions: Female skiers in Vasaloppet had lower incidence of atrial fibrillation and stroke. Male skiers had similar incidence of atrial fibrillation and lower risk of stroke. Men with higher number of races and faster finishing times had the highest incidence of atrial fibrillation. After diagnosis of atrial fibrillation, skiers had lower incidence of stroke and death than did nonskiers with atrial fibrillation. This indicates that although on an individual level atrial fibrillation in well-trained individuals is associated with higher incidence of stroke, on population level, risk of stroke is low and that exercise should not be avoided.

Epilepsy patients commonly exercise less than the general population. Animal studies indicate beneficial effects of physical activity in established epilepsy, while its effect on the development is currently less known. Here, we investigated the incidence of epilepsy during 20 years in a cohort of participants from the long-distance Swedish cross-country ski race Vasaloppet (n = 197,685) and compared it to the incidence of non-participating-matched controls included in the Swedish population register (n = 197,684). Individuals diagnosed with diseases such as stroke and epilepsy before entering the race were excluded from both groups. Experimentally, we also determined how physical activity could affect the development of epilepsy in epilepsy-prone synapsin II knockout mice (SynIIKO), with and without free access to a running wheel. We identified up to 40–50% lower incidence of epilepsy in the Vasaloppet participants of all ages before retirement. A lower incidence of epilepsy in Vasaloppet participants was seen regardless of gender, education and occupation level compared to controls. The participants included both elite and recreational skiers, and in a previous survey, they have reported a higher exercise rate than the general Swedish population. Sub-analyses revealed a significantly lower incidence of epilepsy in participants with a faster compared to slower finishing time. Dividing participants according to specified epilepsy diagnoses revealed 40–50% decrease in focal and unspecified epilepsy, respectively, but no differences in generalized epilepsy. Voluntary exercise in seizure-prone SynIIKO mice for 1 month before predicted epilepsy development decreased seizure manifestation from > 70 to 40%. Brain tissue analyses following 1 month of exercise showed increased hippocampal neurogenesis (DCX-positive cells), while microglial (Iba1) and astrocytic activation (GFAP), neuronal Map2, brain-derived neurotrophic factor and its receptor tyrosine receptor kinase B intensity were unaltered. Continued exercise for additionally 2 months after predicted seizure onset in SynIIKO mice resulted in a 5-fold reduction in seizure manifestation (from 90 to 20%), while 2 months of exercise initiated at the time of predicted seizure development gave no seizure relief, suggesting exercise-induced anti-epileptogenic rather than anti-convulsive effect. The clinical study and the experimental findings in mice indicate that physical activity may prevent or delay the development of epilepsy.

Physical activity has been proposed to be beneficial for prevention of depression, although the importance of exercise intensity, sex-specific mechanisms, and duration of the effects need to be clarified. Using an observational study design, following 395,369 individuals up to 21 years we studied whether participation in an ultralong-distance cross-country ski race was associated with lower risk of developing depression. Skiers (participants in the race) and matched non-skiers from the general population (non-participants in the race) were studied after participation (same year for non-participation) in the race using the Swedish population and patient registries. The risk of depression in skiers (n = 197,685, median age 36 years, 38% women) was significantly lower, to nearly half of that in non-skiers (adjusted hazard ratio, HR 0.53) over the follow-up period. Further, a higher fitness level (measured as the finishing time to complete the race, a proxy for higher exercise dose) was associated with lower incidence of depression in men (adjusted HR 0.65), but not in women. Our results support the recommendations of engaging in physical activity as a preventive strategy decreasing the risk for depression in both men and women. Furthermore, the exercise could reduce risk for depression in a dose-dependent matter, in particular in males.

Abstract Background Physical activity might reduce the risk of developing dementia. However, it is still unclear whether the protective effect differs depending on the subtype of dementia. We aimed to investigate if midlife physical activity affects the development of vascular dementia (VaD) and Alzheimer’s disease (AD) differently in two large study populations with different designs. Methods Using a prospective observational design, we studied whether long-distance skiers of the Swedish Vasaloppet (n = 197,685) exhibited reduced incidence of VaD or AD compared to matched individuals from the general population (n = 197,684) during 21 years of follow-up (median 10, interquartile range (IQR) 5–15 years). Next, we studied the association between self-reported physical activity, stated twice 5 years apart, and incident VaD and AD in 20,639 participants in the Swedish population-based Malmo Diet and Cancer Study during 18 years of follow-up (median 15, IQR 14–17 years). Finally, we used a mouse model of AD and studied brain levels of amyloid-β, synaptic proteins, and cognitive function following 6 months of voluntary wheel running. Results Vasaloppet skiers (median age 36.0 years [IQR 29.0–46.0], 38% women) had lower incidence of all-cause dementia (adjusted hazard ratio (HR) 0.63, 95% CI 0.52–0.75) and VaD (adjusted HR 0.49, 95% CI 0.33–0.73), but not AD, compared to non-skiers. Further, faster skiers exhibited a reduced incidence of VaD (adjusted HR 0.38, 95% CI 0.16–0.95), but not AD or all-cause dementia compared to slower skiers. In the Malmo Diet and Cancer Study (median age 57.5 years [IQR 51.0–63.8], 60% women), higher physical activity was associated with reduced incidence of VaD (adjusted HR 0.65, 95% CI 0.49-0.87), but not AD nor all-cause dementia. These findings were also independent of APOE-ε4 genotype. In AD mice, voluntary running did not improve memory, amyloid-β, or synaptic proteins. Conclusions Our results indicate that physical activity in midlife is associated with lower incidence of VaD. Using three different study designs, we found no significant association between physical activity and subsequent development of AD.

Background. Asthma prevalence is high among elite endurance athletes, but little is known about its prevalence among competitive recreational athletes. The aim of this study was to determine the prevalence of self-reported asthma and asthma medication use among competitive recreational endurance athletes and their association with training. Methods. A web survey on asthma and medication was conducted among 38,603 adult participants of three Swedish endurance competitions (cross-country running, cross-country skiing, and swimming). Results. The overall response rate was 29%. The prevalence of self-reported asthma (physician-diagnosed asthma and use of asthma medication in the last 12 months) was 12%. Among those reporting asthma, 23% used inhaled corticosteroids and long-acting beta-agonists daily. We found no association between training volume and daily use of asthma medication, except a trend in relation to short-acting beta-agonists. Independent predictors of self-reported asthma were female sex, allergic rhinitis, previous eczema, family history of asthma, cycling, and training for >5 h 50 min/week. Conclusions. The prevalence of self-reported asthma among Swedish competitive recreational endurance athletes appears to be higher than that in the general Swedish population. A large proportion of recreational athletes were reported with asthma use medications, indicating an association between high physical activity and self-reported asthma among competitive recreational athletes.

ABSTRACT It is not known how physical exercise affects the risk of different types of fractures, especially in highly active individuals. To investigate this association, we studied a cohort of 118,204 men and 71,757 women who from 1991 to 2009 participated in Vasaloppet, a long-distance cross-country skiing race in Sweden, and 505,194 nonparticipants frequency-matched on sex, age, and county of residence from the Swedish population. Participants ranged from recreational exercisers to world-class skiers. Race participation, distance of race run, number of races participated in, and finishing time were used as proxies for physical exercise. Incident fractures from 1991 to 2010 were obtained from national Swedish registers. Over a median follow-up of 8.9 years, 53,175 fractures of any type, 2929 hip, 3107 proximal humerus, 11,875 lower leg, 11,733 forearm, and 2391 vertebral fractures occurred. In a Cox proportional hazard regression analysis using time-updated exposure and covariate information, participation in the race was associated with an increased risk of any type of fracture (hazard ratio [HR], 1.02; 95% CI, 1.00 to 1.05); forearm fractures had an HR, 1.11 with a 95% CI, 1.06 to 1.15. There was a lower risk of hip (HR, 0.75; 95% CI, 0.67 to 0.83), proximal humerus (HR, 0.90; 95% CI, 0.82 to 0.98), and lower leg fractures (HR, 0.93; 95% CI, 0.89 to 0.97), whereas the HR of vertebral fracture was 0.97 with a 95% CI, 0.88 to 1.07. Among participants, the risk of fracture was similar irrespective of race distance and number of races run. Participants close to the median finishing time had a lower risk of fracture compared with faster and slower participants. In summary, high levels of physical exercise were associated with a slightly higher risk of fractures of any type, including forearm fractures, but a lower risk of hip, proximal humerus, and lower leg fractures. © 2018 American Society for Bone and Mineral Research.

We studied the relationship between taking part in a long-distance ski race and incidence of cardiovascular diseases (CVDs) to address the hypothesis that lifestyle lowers the incidence. A cohort of 399 630 subjects in Sweden, half were skiers in the world's largest ski race, and half were non-skiers. Non-skiers were frequency matched for sex, age, and year of race. Individuals with severe diseases were excluded. The endpoints were death, myocardial infarction, or stroke. The subjects were followed up for a maximum of 21.8 years and median of 9.8 years. We identified 9399 death, myocardial infarction, or stroke events among non-skiers and 4784 among the Vasaloppet skiers. The adjusted hazard ratios (HRs) comparing skiers and non-skiers were 0.52 [95% confidence interval (CI) 0.49-0.54] for all-cause mortality, 0.56 (95% CI 0.52-0.60) for myocardial infarction and 0.63 (95% CI 0.58-0.67) for stroke and for all three outcomes 0.56 (95% CI 0.54-0.58). The results were consistent across subgroups: age, sex, family status, education, and race year. For skiers, a doubling of race time was associated with a higher age-adjusted risk of 19%, and male skiers had a doubled risk than female skiers, with a HR 2.06 (95% CI 1.89-2.41). The outcome analyses revealed no differences in risk of atrial fibrillation between skiers and non-skiers. This large cohort study provides additional support for the hypothesis that individuals with high level of physical activity representing a healthy lifestyle, as evident by their participation in a long-distance ski race, have a lower risk of CVD or death.

A highly increased risk of amyotrophic lateral sclerosis (ALS) has been suggested among professional athletes. We aimed to examine whether long distance cross-country skiers have also a higher risk of ALS and whether the increased risk was modified by skiing performance. We followed 212,246 cross-country skiers in the Swedish Vasaloppet cohort and a random selection of 508,176 general Swedes not participating in the Vasaloppet during 1989-2010. The associations between cross-country skiing as well as skiing performance (i.e., type of race, finishing time and number of races) and the consequent risk of ALS were estimated through hazard ratios (HRs) derived from Cox model. During the study, 39 cases of ALS were ascertained among the skiers. The fastest skiers (100-150% of winner time) had more than fourfold risk of ALS (HR 4.31, 95% confidence interval [CI] 1.78-10.4), as compared to skiers that finished at >180% of winner time. Skiers who participated >4 races during this period had also a higher risk (HR 3.13, 95% CI 1.37-7.17) than those participated only one race. When compared to the non-skiers, the fastest skiers still had a higher risk (HR 2.08, 95% CI 1.12-3.84), as skiers who had >4 races (HR 1.88, 95% CI 1.05-3.35), but those finishing at >180% of winner time had a lower risk (HR 0.46, 95% CI 0.24-0.87). In conclusion, long distance cross-country skiing is associated with a higher risk of ALS, but only among the best skiers; recreational skiers appear to have a largely reduced risk.

Background: The prevalence of asthma among elite endurance athletes is high. Less is known about the prevalence among competitive recreational athletes. This cross-sectional study aimed to determine the self-reported prevalence of asthma and asthma medication use and their association with training, among Swedish competitive recreational endurance athletes. Methods: A validated questionnaire was e-mailed to the 38 603 registered participants 18 years and older of three Swedish endurance competitions. A total of 10 737 athletes responded. A binary logistic regression model were used for predictor analysis. Results: Overall response rate was 29%. The prevalence of current asthma (physician-diagnosed asthma using asthma medication last 12 months) was 12%. Among these, 23% used daily inhaled corticosteroids and long-acting beta-agonists (ICS + LABA). No association between training volume and asthma medicine usage was found. Independent predictors of self-reported current asthma were female sex, allergy, previous eczema, having a family history of asthma, cycling as main sport and training more than 5 hours and 50 minutes per week. Conclusions: The prevalence of current asthma among Swedish competitive recreational endurance athletes appears to be higher than in a general Swedish population. A large proportion of asthmatic athletes use fixed combination ICS + LABA. The study supports the association between high physical activity and current asthma.

Background Physical activity is of benefit for primary prevention of cardiovascular diseases, but it appears to increase the risk for atrial fibrillation. We aimed to study a cohort of patients following a first stroke in individuals with previous high physical activity, compare them to the general population with respect to recurrent stroke and death, and relate these to atrial fibrillation. Methods and Results From the participants of the Vasaloppet, the world's largest ski‐race, and matched individuals from the general population (n=708 604), we identified 5964 patients hospitalized with a first‐time stroke between 1994 and 2010. Individuals with severe diseases were excluded. One half percent of skiers and 1% of nonskiers were hospitalized due to stroke. The incidence rate was 8.3 per 100 person‐years among skiers and 11.1 among nonskiers. The hazard ratio ( HR ) for recurrent stroke or death between the 2 groups was 0.76 (95% CI 0.67 to 0.86). The result was consistent in subgroups. The HR for death was 0.66 (95% CI 0.56 to 0.78) and for recurrent stroke 0.82 (95% CI 0.70 to 0.96). After adjustment for smoking and socioeconomic factors, the HR for death was consistent at 0.70 (95% CI 0.56 to 0.87) while the HR for recurrent stroke was not statistically significant. Outcomes for skiers with atrial fibrillation tended to show a lower risk than for nonskiers. Conclusions This large cohort study supports the hypothesis that patients with a stroke and with prior regular physical activity have a lower risk of death, while their risk for recurrent stroke is similar to that of nonskiers. The skiers had a higher incidence of atrial fibrillation, but still no increased risk of recurring stroke.

Aims To study whether a high level of physical activity prior to myocardial infarction (MI) also protects against recurrent MI (re-MI) or death.Methods and Results A longitudinal study of a primary cohort consisting of 204,038 skiers with a proved substantially high level of physical activity in the world's largest long-distance ski race, Vasaloppet, and 499,543 non-skiers selected from the Swedish population. Individuals with severe diseases at baseline were excluded. In the nationwide clinical register, Swedeheart, we identified 7092 individuals with a first MI incident between 1989 and 2010. Of these, 1039 (0.5%) were skiers and 6053 (1.2%) were non-skiers. One hundred and sixty-three (15.7%) skiers and 1352 (22.3%) non-skiers suffered a re-MI or died during follow-up (median 4.44 years), corresponding to an incidence rate of 38.9 (95% confidence interval (CI) 33.2-45.4)/1000 person-years and 55.6 (95% CI 52.7-58.7)/1000 person-years, respectively. Severity of MI in both groups was the same. For skiers compared to non-skiers the unadjusted hazard ratio (HR) for re-MI was 0.66 (95% CI 0.52-0.82). For death or re-MI, HR was 0.70 (95% CI 0.59-0.82) with consistent results in subgroups based on race year, age, gender, education level, marital status. After adjustment for also smoking, diabetes, hypertension and cardiovascular medication, HR was 0.80 (95% CI 0.67-0.97).Conclusions This large cohort study supports the hypothesis that patients with MI and with prior physical activity and healthy lifestyle, as evidenced by their participation in a long-distance ski race, have a lower risk of subsequent re-MI or death.