Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
Karen Milton, Nick Cavill, Anna Chalkley, Charlie Foster, Sjaan Gomersall, Maria Hagstromer, Paul Kelly, Tracy Kolbe-Alexander, Jacqueline Mair, Matthew McLaughlin, James Nobles, Lindsey Reece, Trevor Shilton, Ben J. Smith, and Jasper Schipperijn
Background: The International Society for Physical Activity and Health (ISPAH) is a leading global organization working to advance research, policy, and practice to promote physical activity. Given the expanding evidence base on interventions to promote physical activity, it was timely to review and update a major ISPAH advocacy document—Investments that Work for Physical Activity (2011). Methods: Eight investment areas were agreed upon through consensus. Literature reviews were conducted to identify key evidence relevant to policymakers in each sector or setting. Results: The 8 investment areas were as follows: whole-of-school programs; active transport; active urban design; health care; public education; sport and recreation; workplaces; and community-wide programs. Evidence suggests that the largest population health benefit will be achieved by combining these investments and implementing a systems-based approach. Conclusions: Establishing consensus on ‘what works’ to change physical activity behavior is a cornerstone of successful advocacy, as is having appropriate resources to communicate key messages to a wide range of stakeholders. ISPAH has created a range of resources related to the new investments described in this paper. These resources are available in the ‘advocacy toolkit’ on the ISPAH website (www.ispah.org/resources).
Sebastien F.M. Chastin, Duncan E. McGregor, Stuart J.H. Biddle, Greet Cardon, Jean-Philippe Chaput, Philippa M. Dall, Paddy C. Dempsey, Loretta DiPietro, Ulf Ekelund, Peter T. Katzmarzyk, Michael Leitzmann, Emmanuel Stamatakis, and Hidde P. Van der Ploeg
Background: Crucial evidence gaps regarding: (1) the joint association of physical activity and sedentary time with health outcomes and (2) the benefits of light-intensity physical activity were identified during the development of recommendations for the World Health Organization Guidelines on physical activity and sedentary behavior (SB). The authors present alternative ways to evidence the relationship between health outcomes and time spent in physical activity and SB and examine how this could be translated into a combined recommendation in future guidelines. Methods: We used compositional data analysis to quantify the dose–response associations between the balance of time spent in physical activity and SB with all-cause mortality. The authors applied this approach using 2005–2006 National Health and Nutrition Examination Survey accelerometer data. Results: Different combinations of time spent in moderate- to vigorous-intensity physical activity, light-intensity physical activity, and SB are associated with similar all-cause mortality risk level. A balance of more than 2.5 minutes of moderate- to vigorous-intensity physical activity per hour of daily sedentary time is associated with the same magnitude of risk reduction for all-cause mortality as obtained by being physically active according to the current recommendations. Conclusion: This method could be applied to provide evidence for more flexible recommendations in the future with options to act on different behaviors depending on individuals’ circumstances and capacity.
Samar Ezzina, Clément Roume, Simon Pla, Hubert Blain, and Didier Delignières
The analysis of stride series revealed a loss of complexity in older people, which correlated with the falling propensity. A recent experiment evidenced an increase of walking complexity in older participants when they walked in close synchrony with a younger companion. Moreover, a prolonged experience of such synchronized walking yielded a persistent restoration of complexity. This result, however, was obtained with a unique healthy partner, and it could be related to a particular partner’s behavior. The authors’ aim was to replicate this important finding using a different healthy partner and to compare the results to those previously obtained. The authors successfully replicated the previous results: synchronization yielded an attraction of participants’ complexity toward that of their partner and a restoration of complexity that persisted in two posttests, 2 and 6 weeks after the end of the training sessions. This study shows that this complexity restoration protocol can be applied successfully with another partner, and allows us to conclude that it can be generalized.
Jason P. Brandenburg, Iris A. Lesser, Cynthia J. Thomson, and Luisa V. Giles
Background: Regular physical activity and higher cardiorespiratory (CR) fitness enhance immune function, possibly reducing coronavirus disease 2019 (COVID-19) infection severity. The aim was to assess the association between physical activity and self-reported CR fitness on COVID-19 infection characteristics. Methods: Participants formerly testing positive for COVID-19 completed an online questionnaire measuring COVID-19 infection characteristics and complications, self-reported CR fitness level, physical activity, and sociodemographic and health-related characteristics. Self-reported CR fitness was determined as the pace to cover 4.8 km without becoming overly fatigued (with slow walking, brisk walking, jogging, and running corresponding to low, moderate, good, and excellent levels of fitness, respectively). Results: A total of 263 individuals completed the survey. Compared with the lowest level of self-reported CR fitness, the odds of hospitalization significantly decreased by 64% (odds ratio = 0.36; 95% confidence interval, 0.13–0.98; P = .04) in individuals reporting the ability to maintain a brisk walk. In individuals reporting the ability to maintain a jogging pace, the further reduction in hospitalization was not significant (odds ratio = 0.22; 95% confidence interval, 0.05–1.04; P = .05). For COVID-19 symptom severity and number, there were no significant associations with self-reported CR fitness or physical activity levels. Conclusions: For individuals with low self-reported CR fitness, improving CR fitness represents a strategy to reduce the risk of hospitalization from COVID-19.
Pauliina Husu, Kari Tokola, Henri Vähä-Ypyä, Harri Sievänen, Jaana Suni, Olli J. Heinonen, Jarmo Heiskanen, Kaisu M. Kaikkonen, Kai Savonen, Sami Kokko, and Tommi Vasankari
Background: Studies measuring physical activity (PA) and sedentary behavior on a 24/7 basis are scarce. The present study assessed the feasibility of using an accelerometer at the hip while awake and at the wrist while sleeping to describe 24/7 patterns of physical behavior in working-aged adults by age, sex, and fitness. Methods: The study was based on the FinFit 2017 study where the physical behavior of 20- to 69-year-old Finns was assessed 24/7 by triaxial accelerometer (UKKRM42; UKK Terveyspalvelut Oy, Tampere, Finland). During waking hours, the accelerometer was kept at the right hip and, during time in bed, at the nondominant wrist. PA variables were based on 1-min exponential moving average of mean amplitude deviation of the resultant acceleration signal analyzed in 6-s epochs. The angle for the posture estimation algorithm was used to identify sedentary behavior and standing. Evaluation of time in bed was based on the wrist movement. Fitness was estimated by the 6-min walk test. Results: A total of 2,256 eligible participants (mean age 49.5 years, SD = 13.5, 59% women) wore the accelerometer at the hip 15.7 hr/day (SD = 1.4) and at the wrist 8.3 hr/day (SD = 1.4). Sedentary behavior covered 9 hr 18 min/day (SD = 1.8 hr/day), standing nearly 2 hr/day (SD = 0.9), light PA 3.7 hr/day (SD = 1.3), and moderate to vigorous PA 46 min/day (SD = 26). Participants took 7,451 steps per day (SD = 2,962) on average. Men were most active around noon, while women had activity peaks at noon and at early evening. The low-fit tertile took 1,186 and 1,747 fewer steps per day than the mid- and high-fit tertiles (both p < .001). Conclusions: One triaxial accelerometer with a two wear-site approach provides a feasible method to characterize hour-by-hour patterns of physical behavior among working-aged adults.
Paul Mackie, Gary Crowfoot, Prajwal Gyawali, Heidi Janssen, Elizabeth Holliday, David Dunstan, and Coralie English
Background: Interrupting prolonged sitting can attenuate postprandial glucose responses in overweight adults. The dose–response effect in stroke survivors is unknown. The authors investigated the effects of interrupting 8 hours of prolonged sitting with increasingly frequent bouts of light-intensity standing-based exercises on the postprandial glucose response in stroke survivors. Methods: Within-participant, laboratory-based, dose-escalation trial. Participants completed three 8-hour conditions: prolonged sitting and 2 experimental conditions. Experimental conditions involved light-intensity standing-based exercises of increasing frequency (2 × 5 min to 6 × 5 min bouts). Postprandial glucose is reported. Results: Twenty-nine stroke survivors (aged 66 y) participated. Interrupting 8 hours of prolonged sitting with light-intensity standing-based exercises every 90 minutes significantly decreased postprandial glucose (positive incremental area under the curve; −1.1 mmol/L·7 h; 95% confidence interval, −2.0 to −0.1). In the morning (08:00–11:00), postprandial glucose decreased during the 4 × 5 minutes and 6 × 5 minutes conditions (positive incremental area under the curve; −0.8 mmol/L·3 h; 95% confidence interval, −1.3 to −0.3 and −0.8 mmol/L·3 h; 95% confidence interval, −1.5 to −0.2, respectively) compared with prolonged sitting. Conclusion: Interrupting 8 hours of prolonged sitting at least every 90 minutes with light-intensity standing-based exercises attenuates postprandial glucose in stroke survivors. During the morning, postprandial glucose is attenuated when sitting is interrupted every 60 and 90 minutes.
Hillary H. Holmes, Randall T. Fawcett, and Jaimie A. Roper
Walking is an integral indicator of human health commonly investigated while walking overground and with the use of a treadmill. Unlike fixed-speed treadmills, overground walking is dependent on the preferred walking speed under the individuals’ control. Thus, user-driven treadmills may have the ability to better simulate the characteristics of overground walking. This pilot study is the first investigation to compare a user-driven treadmill, a fixed-speed treadmill, and overground walking to understand differences in variability and mean spatiotemporal measures across walking environments. Participants walked fastest overground compared to both fixed and user-driven treadmill conditions. However, gait cycle speed variability in the fixed-speed treadmill condition was significantly lower than the user-driven and overground conditions, with no significant differences present between overground and user-driven treadmill walking. The lack of differences in variability between the user-driven treadmill and overground walking may indicate that the user-driven treadmill can better simulate the variability of overground walking, potentially leading to more natural adaptation and motor control patterns of walking.