Wellness Check: Exercise

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. 

Physical activity and sleep may have synergistic effects on health

1. Physical activity levels at or above the WHO guidelines threshold eliminated most of the negative effects of poor sleep on mortality.

2. The negative effects of poor sleep were further amplified with lower levels of physical activity.

Evidence Rating Level: 2 (Good)

Beyond the independent health effects that physical activity and sleep have on health, there has been a lack of studies examining their effect in combination. As such, the goal of this study was to investigate the impact of these two variables on all-cause, cardiovascular and cancer mortality.

This prospective cohort study recruited 380,055 participants from the UK Biobank between 2006-2010. The study included adults aged 37-73 years from 22 recruitment centers within the UK. Participants with a past history of cardiovascular disease (CVD), cancer, obstructive sleep apnea, or class III obesity at baseline were excluded. Participants completed questionnaires and interviews with respect to their physical activity levels and sleep patterns. Participants were followed up on health outcomes to the date of death or censorship (May 2020), whichever came first.

Compared with participants who had high physical activity and health sleep patterns, those who had both poor sleep and low physical activity had the highest mortality risk for all-cause, total cardiovascular and cancer death. Compared with no physical activity, levels that were above the World Health Organization (WHO) recommended threshold appeared to eliminate the negative associations of poor sleep and mortality. The strengths of this paper included its large sample size, long follow-up of 11 years and collection of a wide range of variables. The limitations included the self-reported nature of physical activity and sleep patterns, as well as the various exclusion criteria which may limit the study’s generalizability. This study’s findings not only suggested that a focus on both physical activity and sleep may lead to greater protective effects on health outcomes; but that there may be potential to further explore this association with future trials.

Hereditary hemochromatosis risk genotypes may improve endurance performance in male athletes

1. Individuals possessing the medium or high risk HFE genotypes outperformed those with lower risk genotypes in a 10km cycling time trial.

2. Individuals in the medium or high risk HFE genotypes possessed a greater VO_2peak compared with those with a lower risk genotype.

Evidence Rating Level: 2 (Good)

Mutations in the human homeostatic iron regulator (HFE) gene can lead to excessive amounts of iron in the bloodstream. At toxic levels, this may cause hemochromatosis; however, if below this threshold, higher iron content may result in enhanced endurance capacity due to the increased production of red blood cells. The purpose of this study was to determine whether certain HFE genotypes were associated with enhanced endurance performance [lower 10km cycling time trial or an increase in maximal oxygen uptake (VO_2peak )]. This retrospective cohort study recruited 100 competitive male athletes from a variety of sports backgrounds. Participants in this study were included if they had various HFE risk genotypes and were training and/or competing for ≥8hrs week for 9 out of 12 months out of the year for at least 3 years. For the assessment, athletes completed a 10km cycling time trial as well as a VO_2peak test on four different occasions, 1 week apart.

The results of this study demonstrated that high risk HFE genotypes were associated with greater endurance performance in the 10km cycling time trial compared to lower risk HFE genotypes. Similarly, athletes with high risk HFE risk genotypes tended to have a higher VO_2peak . The study’s greatest strength was the protocol, which instructed athletes to maintain regular sleeping and eating habits, as well as repeat testing which helped increase the strength of the association. However, the very selective sample size of elite male athletes limited the generalizability of the results. Nonetheless, the study’s findings suggest the importance of monitoring and optimizing an athlete’s iron status through supplementation under the guidance of health professionals, as the latter could have a significant impact on endurance performance.

Regular exercise may reduce episodes of disinhibited and overeating  

1. The exercise group displayed a 5% reduction in overeating episodes compared to the control group

2. In comparison to the control group, the exercise group demonstrated an increase in dietary restraint and a reduction in disinhibited eating driven by internal disinhibition

Evidence Rating Level: 2 (Good)

Hedonic eating habits represent a difficult barrier to overcome with respect to weight control, as they can be influenced by various emotional states. Although exercising has the ability to regulate weight over time, little is known about its ability to indirectly affect eating behaviors. As a result, the primary goal of this study was to determine the effect of a 12-week exercise program on episodes of overeating as well as eating behaviors.

This randomized control trial included 49 inactive adult women who had a body mass index of 25-40 kg/m² and a history of stress-induced overeating. Patients who recently lost weight or who were currently enrolled in a weight loss program were excluded. Participants were randomized to either a 12-week exercise group or the control group where no changes were made to their prior exercising habits. Further, all participants completed questionnaires to assess their eating patterns using ecological momentary assessments. The results of this study demonstrated that the exercise group reported a 5% reduction in overeating episodes compared to the control group. Further, participants in the exercise group exhibited an increase in dietary restraint, a reduction in disinhibited eating and were less likely to give into dietary temptation compared to the control group. One key strength of this study was that participants were assessed over a 14-day period in real time under free living conditions. Conversely, the inclusion of only women in this study limits its generalizability to men. Nonetheless, this study’s findings support the hypothesis that exercise may positively impact eating behaviors among women who are overweight or obese.

Active workstations may improve daily standing and step counts

1. Sit-to-stand desks may be more successful than treadmill desks in breaking up daily sedentary behavior even after a year of use.

2. Total daily sedentary did not differ significantly between the three groups (seated-desk control vs. sit-to-stand desk vs. treadmill desk group) after one year

Evidence Rating Level: 1 (Excellent)

Though active workstations have become a popular solution to prolonged sedentary behavior, little is known about their long-term effects of increasing standing and stepping behaviors. As a result, this study sought to analyze the influence of these workstations on total sedentary behavior as well as several activity variables when compared to the control group at 3,6 and 12 month follow-up.

In this randomized controlled trial with a three-arm cluster design, 66 office workers aged 18-65 years old were recruited. In order to be eligible, participants were required to meet the following criteria: BMI>25 mg/kg^-2, not engaged in structured physical activity >2 days per week, and having a seated desk job. Participants were randomized into a treadmill desk group (n=22), a sit-to-stand group (n=23), and a control group (n=21). Activity was monitored using an activPAL^TM monitor and participants self-reported any activity when the device was not worn (e.g. while showering, sleeping).

The results of this study demonstrated that the mean total daily sedentary time at one year did significantly differ . At 3 months, only the treadmill desk group only reported greater total daily stepping at the . However, only the sit-to-stand group reported a sustained increase in activity until the 12-month mark. Strengths of this study included the randomized controlled intervention of 2 active workstations and the long-term follow-up. Conversely, some of its limitations included the smaller sample size and smaller proportion of women comparative to previous studies on this topic. Overall, this study suggested that sit-to-stand desks may result in more frequent bouts of activity compared to treadmill desk users even after a year of use.

Image: PD

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