The manipulation of exercise intensity in team sports constraints players and teams' technical, physical, and tactical behavior. According to that, the manipulation of the duration and the number of ...repetitions (i.e., using a continuous or a fractional method) of an exercise should constraint the overall exercise intensity and consequently its physical, technical and tactical demands. Thus, the aim of this study was to identify the effects of the use of a continuous or fractional method in external and internal load of players in football. The results show that the manipulation of the duration and the number of repetitions, using a continuous or a fractional method constraints external load of players. It means that coaches can constraint the time or the number of repetitions of the exercise according to the external load demands required for the training session.
Background and Objective: Cardiovascular and sports experts recommend the use of oxygen consumption cost indicators, heart rate and fatigue index to control work pressure in sports and ...rehabilitation. Meanwhile, it is very common to control the intensity of exercise by heart rate index. However, the maximum heart rate (HRmax) must first be measured or estimated as the basis for the calculations. The purpose of the present study is to evaluate the validity of HRmax estimation equations in healthy children. Materials and Methods: The HRmax was measured and estimated in 205 healthy boys between 8 and 12 years old by two methods, Bruce's incremental exercise test and special equations for children. In order to compare the estimated and measured HRmax, Pearson's correlation, t-correlated and root mean square error (RMSE) were used. Results: A weak correlation between estimated and measured HRmax was observed (R=0.09-0.18). A significant difference was observed between the estimated and measured HRmax (beats per minute = 1.4-4.8) (P<0.05). So, the Nikolaidis equation led to a significant overestimation and the Shargal and Gelbert equations led to a significant underestimation of the HRmax. Also, the root mean square error values for HRmax estimation equations were high (RMSE = 6.9 - 7.4 beats per minute). Conclusion: Considering the ineffectiveness of foreign equations for estimating the HRmax in Iranian children, it is recommended to design native equations for estimating the HRmax for Iranian children.
ObjectiveExamine the relationship between 5P risk score – predictor of persistent post-concussive symptoms (PPCS) – with physical activity (PA) and exercise characteristics among adolescents ...recovering from concussion.DesignProspective cohort study.SettingSports medicine center.ParticipantsAdolescents evaluated ≤14 days of concussion (n=44, 50% female, 14.9±1.7 years).Assessment of Risk FactorsParticipants were grouped by 5P score (high risk 9–12; medium/low risk 0–8) at initial evaluation and recorded PA and exercise sessions with an activity tracker.Outcome MeasuresWe compared demographic and injury variables, exercise characteristics duration, frequency, intensity (maximum and average heart rates) and PA (steps/day) between high- and medium/low-risk groups.Main ResultsSeventeen participants (39%) had a high-risk score. The high-risk group had a significantly higher proportion of females (88% vs 26%, p<0.001) and those with depression history (41% vs 7%, p=0.02) than the medium/low-risk group. Those with a high-risk 5P score exercised less often (r=-0.31, p=0.04), for shorter duration (r=-0.41, p=0.007), and took fewer steps/day (r=-0.37, p=0.01), but there was a weak and non-significant correlation with exercise intensity. After adjusting for the effect of sex and depression history, a higher 5P risk score predicted lower maximum exercise intensity (β= -3.37; 95% CI= -6.43, -0.32; p=0.03) but no other PA/exercise characteristics.Conclusions5P risk score predicted exercise intensity in the 2 weeks after initial concussion assessment. Given the benefits of PA and exercise during concussion recovery, clinicians may use the 5P risk score to predict those at increased PPCS risk and promote exercise prescription in this population.Trial registrationNCT04199247
Exercise intensity is traditionally prescribed using %HRmax, %HRR, %VO2max, or %VO2R. Recently, the Talk Test (TT) has been proposed as an alternative method to guide exercise intensity. However, it ...is unknown if prescribing exercise intensity solely using the TT can provoke training responses that are comparable to traditional guidelines. This study compared the responses to training using either the TT or %HRR. Forty-four subjects (17 males and 27 females: age=20.4±3.02 years; body height=170.5±9.79 cm; body weight=71.9±13.63 kg) completed an incremental maximal cycle ergometer test, were stratified by VO2max and gender, and randomly assigned to training groups guided by either %HRR (n=20) or the TT (n=24). Both groups completed 40-minute training sessions three days per week for 10 weeks. In the HRR group, exercise intensity was targeted (per ACSM guidelines) at 40-59% HRR for weeks 1-4, 50-59% HRR for weeks 5-8, and 60-79% HRR for weeks 9-10. In the TT group, exercise intensity was targeted at the highest power output (PO) that still allowed for comfortable speech. Changes in VO2max, peak power output (PPO), VO2 at ventilatory threshold (VT), and PO at VT were compared between the groups using two-way ANOVA with repeated measures. There were significant (p0.05) interaction effect. Guiding exercise prescription using the TT is a simple and effective method for prescribing exercise intensity and elicits improvements in exercise performance that are comparable to the traditional %HRR guidelines.
BackgroundBiventricular volume, aortic and pulmonary flow assessment by cardiovascular magnetic resonance (CMR) allows accurate direct quantification of aortic and pulmonary flow and indirect ...quantification of mitral and tricuspid regurgitation. Exercise cardiovascular magnetic resonance (Ex-CMR) combines the preferred method of exercise stress with the diagnostic capabilities of CMR. Compressed SENSE (CS) is a novel parallel imaging technique, robust to respiratory motion that has not previously been used in Ex-CMR. This study aims to demonstrate the feasibility and utility of performing biventricular function and flow assessment during continuous in-scanner exercise, using vendor supplied CS sequences and commercial analysis software (Circle cvi42).Methods12 healthy volunteers (8 male, age 35±10 years) had CMR imaging (1.5T Philips Ingenia) using a novel free breathing CS protocol at rest and during continuous in-scanner supine cycle exercise (Lode BV) to low and moderate exercise intensities. Target heart rates (THR) were individually prescribed using heart rate reserve (HRR) and an age predicted maximal heart rate model. Participants exercised with no resistance for 1 minute then at an increase of 25W every 2 minutes until target heart rate (THR) were achieved at low (30-39% HRR) and moderate (40-59% HRR) exercise.At rest, the novel CS protocol was validated against our institute’s standard clinical breath-held (BH) sequences (SENSE 2, bSSFP multi-phase, multi-slice SA cines & aortic and pulmonary 2D flow).The Ex-CMR protocol involved:Biventricular volume assessment - free breathing, Compressed SENSE acceleration x 3 (CS3), bSSFP, respiratory navigated, retrospectively gated short axis cine imaging.Flow acquisition - free breathing CS3 aortic and pulmonary through-plane phase contrast imaging.Abstract 109 Figure 1Consecitive free breathing short axis and flow images acquired in the same patient at rest and during continuous exercise to low and moderate exercise intensitiesResultsResting biventricular volumes, aortic and pulmonary flows from CS3 sequences demonstrated very strong correlation with clinical breath held sequences (all correlations r >0.93, p<0.01). Participant’s heart rates remained within the prescribed exercise intensities for each stage (table 1). Examples of exercise image quality are presented in figure 1. Biventricular end-diastolic volumes (EDV) remained unchanged with increasing exercise (with the exception of a drop in right ventricular EDV at moderate exercise), with an increase in stroke volumes (SV) driven by a fall in end systolic volumes (table 2). Aortic and pulmonary stroke volumes similarly rose with increasing exercise intensities, strongly correlating at all exercise intensities with the corresponding stroke volumes acquired from biventricular SA cine imaging (all correlations: r >0.88, p <0.01).Abstract 109 Table 1Physiological response to supine bicycle Ex-CMRExercise intensityRestLowModerate Heart rate reserve (%) of maximal heart rateN/A30-39%40-59%Heart rate (beats per minute)58±6102±5119±5Systolic blood pressure *119±10143±15160±24Diastolic blood pressure *71±876±1375±13Borg rate of perceived exertion6±09.6±1.813.7±2.4Mean work rate (Watts)052±2684±24* n=10, 2 blood pressures un-recordable at moderate exercise intensity.Abstract 109 Table 2Cardiac haemodynamic response to supine bicycle Ex-CMRExercise intensityRestLowModerate Image SequenceClinical breath heldCompressed SENSE 3 free breathingLVEDV (indexed) ml/m2 89±1689±1688±1586±14LVSV (indexed) ml/m2 50±750±757±8*60±7*LVEF (%)57±657±666±7*70±8*Aortic stroke volume (indexed) ml/m2 48±748±755±8*57±8*RVEDV (indexed) ml/m2 89±1690±1587±1585±14**RVSV (indexed) ml/m2 49±849±756±7*59±7*RVEF (%)55±756±665±7*70±6*Pulmonary stroke volume (indexed) ml/m2 49±648±854±7*55±7** p< 0.01, **p<0.05 for differences between exercise stage and rest (CS3 sequence).ConclusionThis is the first study to demonstrate feasibility of biventricular function, aortic and pulmonary flow assessment during continuous Ex-CMR using vendor provided sequences and commercially available analysis software. The developed Compressed SENSE Ex-CMR protocol could easily be adopted across a wide number of centres, potentially allowing assessment of the haemodynamic response to a wide range of cardiovascular diseases, therefore increasing the clinical utility of Ex-CMR.Conflict of InterestN/A
Food reformulation has been suggested as an equitable approach to meeting recommendations to limit free sugars intakes. During reformulation, various ingredients are needed to replace the functional ...properties of sugars, however, the effect this has on levels of calories and “nutrients to limit” has not been examined on a large-scale. This study aimed to identify changes in nutritional composition of foods reformulated to be lower in sugars. Methods: This study was a repeated cross-sectional analysis of prepackaged foods and beverages using the 2013 and 2017 collections of the University of Toronto’s Food Label Database. Products in 2013 and 2017 were matched by barcode (n=6695 matches, after exclusions). Sign tests were used to evaluate difference in sugars contents. Wilcoxon signed rank test was used to evaluate differences in nutritional composition (i.e. calories, fat, saturated fats, sodium, carbohydrates, protein, and fibre) of products with lower sugars contents in 2017. Results: Twenty-two percent of products (n=1492) had changes in sugars contents between 2013 and 2017. In 2017, 10% (n=669) of products were higher in sugars by 39% (3.5 ± 5.0g per 100g/mL, p<0.0001) and 13% (n=882) were lower by 30% (-2.5 ± 2.8g per 100g/mL, p<0.0001). Products that had lower sugar levels in 2017, also had significant reductions in calories (-5.4 ± 22.2kcal per 100g/mL, p<0.0001), and sodium (-34.5 ± 186.9mg per 100g/mL, p<0.0001), and significant, but negligible, differences in saturated fats (0.0 ± 1.26g per 100g/mL, p=0.0435), total fats (-0.1 ± 1.7g per 100g/mL, p=0.0247), and carbohydrates (-0.8 ± 3.4g per 100g/mL, p<0.0001). There were no significant differences for other nutrients. Conclusion: Efforts to lower sugars contents through reformulation between 2013 and 2017 were limited. Although products reformulated to be lower in sugars were also significantly lower in calories, fats, carbohydrates, and sodium, the very small magnitude of these changes may not be sufficient to affect dietary intakes. (CIHR PICDP (JTB, TGF-53893); CIHR Training Program in Public Health Policy (JTB); OGS (JTB); CIHR Strategic Operating Grant (201103SOK-118150); Canadian Stroke Network (201103SOK-01194-000) (MRL); CIHR Sugars and Health (SA2-152805) (MRL); Earle W. McHenry Research Chair unrestricted grant (MRL); One Sweet Film Inc. (MRL).)
