2 Minute Medicine is pleased to announce that we are launching Wellness Check, a new series dedicated to exploring new research evidence focused on wellness. Each week, we will report on articles examining different aspects of wellness, including (but not limited to) nutrition, sleep, reproductive health, substance use and mental health. This week, we explore the latest evidence-based updates in exercise.
Bystander intervention may improve survival after exercise-related sudden cardiac arrest
1. On average, 71% of exercise-related sudden cardiac arrest (SCA) received bystander cardiopulmonary resuscitation (CPR) and 31% had an automated external defibrillator (AED) applied by a bystander.
2. The median survival rate to hospital discharge among exercise related SCA was 32%
Evidence Rating Level: 1 (Excellent)
Sudden cardiac arrest (SCA) is an issue affecting competitive and non-competitive athletes during exercise. Bystanders play an important role in responding to cardiac arrest events however the survival benefits have not been comprehensively examined. As a result, this systematic review seeks to evaluate rate of provision of cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) by bystanders as well as the rates of survival after exercise related SCA.
From 3711 identified records, 29 studies from inception to December 2020 were included in this systematic review. Studies were included if they reported bystander use of CPR and/or AED along with survival outcomes after exercise-relate SCA. Median proportions of bystander CPR and AED use were calculated as well as median rate of survival to hospital discharge. Risk of bias was assessed through the Newcastle-Ottawa Scale and most studies achieved a high score.
Results demonstrated that on average, 71% of exercise related SCA received bystander CPR and 31% had an AED applied by a bystander. In addition, the median survival rate to hospital discharge among exercise related SCA was 32%. It was found that both bystander CPR an AED use were significantly associated with survival after exercise-related SCA. However, this study was limited by the lack of examination of the time from collapse to initiation of CPR or AED which could influence survival outcomes. Nonetheless, this study provides early evidence that suggests the utility of CPR and AED use to improve survival after exercise related SCA.
Physical activity has a weight-independent effect on mortality
1. Higher device-measured physical activity was associated with a lower risk of mortality irrespective of body mass index (BMI).
2. Compared with obese participants, there were no survival benefits of having a normal weight if physical activity remained low.
Evidence Rating Level: 1 (Excellent)
Maintaining a healthy body weight is important to prevent chronic disease. However, the dose-response association between body mass index (BMI) and the risk of premature mortality is debated. Exercise plays an important role in this relationship however current studies are based off self-reported data which are prone to biases. As a result, the primary goal of the present meta-analysis sought to examine the combined association of device-measured total and intensity-specific physical activity and sedentary time with BMI in relation to the risk of all-cause mortality.
From 8 prospective cohorts identified between database inception to July 2018, 34 492 participants (72% women) were included. Participants were included if they were >40 years and recorded at least 10 hours of accelerometer wear time per day for 4 or more days. Exclusion criteria included: <2 years follow-up, BMI <18.5 kg/m2 or who have a history of cardiovascular disease (CVD) or cancer. 9 physical activity-BMI combinations were created for each physical activity intensity exposure.
Results demonstrated that higher device-measured physical activity was associated with a lower risk of mortality irrespective of BMI. Furthermore, compared with obese participants, there were no survival benefits of having a normal weight if physical activity remained low. However, this study was limited as it did not consider changes in physical activity or BMI over time. Nonetheless, the results from this study suggest that physical activity plays an important role in decreasing mortality risk irrespective of weight.
Isometric exercise training may be more effective at blood pressure management than high intensity interval training
1. When compared to high intensity interval training (HIIT), isometric exercise training (IET) produced greater reductions in resting systolic, diastolic and mean blood pressure (BP).
2. Furthermore, HIIT reduced resting heart rate significantly more than IET.
Evidence Rating Level: 1 (Excellent)
There are currently many limitations regarding medication usage to reduce blood pressure (BP) which has sparked an increase utilization of non-pharmacological strategies. Recently, both isometric exercise training (IET) and high intensity interval training (HIIT) have been found to be efficient modes of exercise which have produced significant reductions in blood pressure measurements. However, there is currently a lack of evidence comparing the efficacy of these modalities. Therefore, the present systematic review and meta-analysis seeks to investigate both the individual and combined effects of IET and HIIT on BP.
From 5220 screened articles, 38 studies (n=672 IET and n=911 HIIT) were included from January 2000 to September 2020. Studies were included if they evaluated the effects of either IET or HIIT (for a period of 2-12 weeks) on blood pressure. Participants had no limitations to health or baseline BP status. Risk of bias was evaluated using the TESTEX scale. Random-effects meta-analysis was run for IET and HIIT on BP.
Results demonstrated that IET produced greater reductions in resting systolic, diastolic, and mean blood pressure compared to HIIT. However, HIIT reduced resting heart rate significantly more than IET. The present study was limited by significant heterogeneity for all BP outcomes for both IET and HIIT. However, this may have been mitigated by the utilization of a random-effects model. In conclusion, these results demonstrate the efficacy of both interventions on lowering BP.
Knee extensor muscle weakness may be a risk factor for osteoarthritis
1. Low quality evidence demonstrates that knee extensor muscle weakness increased the odds of symptomatic and radiographic knee osteoarthritis in men and women.
2. In women with a previous knee injury, low quality evidence shows no association between knee extensor muscle weakness and symptomatic and radiographic tibiofemoral osteoarthritis.
Evidence Rating Level: 2 (Good)
Knee osteoarthritis is a leading cause of pain and disability in older adults with no curative options. One non-pharmacologic option is to address knee extensor muscle weakness which may help to regulate joint loads critical to maintaining the homeostasis of cartilage. The objective of the present systematic review and meta-analysis was to update a prior study from 2015 which investigated the association between knee extensor muscle weakness and the risk of incident symptomatic or radiographic patellofemoral or tibiofemoral osteoarthritis in women and men.
From 1331 screened records, 11 studies (n=46 819) were included in an updated search in May 2021. Longitudinal studies (with at least 2 year follow up) were included if they assessed knee extensor muscle strength at baseline and assessed structural or symptomatic knee osteoarthritis. Studies were excluded if participants had known symptomatic or radiographic knee osteoarthritis at baseline or had rheumatologically diseases. Quality of the evidence was assessed using the Grading of Recommendations Assessments, Development and Evaluation (GRADE).
Results demonstrated low quality evidence that knee extensor muscle weakness increased the odds of symptomatic and radiographic knee osteoarthritis in men and women. Furthermore, in women with a previous knee injury, low quality evidence shows no association between knee extensor muscle weakness and symptomatic and radiographic tibiofemoral osteoarthritis. However, the present was limited due to considerable heterogeneity included in the studies with respect to study populations and clinical definitions. Nonetheless, the current findings suggest that improving knee extensor strength may help prevent knee osteoarthritis.
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