Increasing cadence with a metronome and running barefoot changes the sagittal kinematics of the lower limbs and trunk.

The purpose was to compare two non-laboratory based running retraining programs on lower limb and trunk kinematics in recreational runners. Seventy recreational runners (30 ± 7.3 years old, 40% female) were randomised to a barefoot running group (BAR), a group wearing a digital metronome with their basal cadence increased by 10% (CAD), and a control group (CON). BAR and CAD groups included intervals from 15 to 40 min over 10 weeks and 3 days/week. 3D sagittal kinematics of the ankle, knee, hip, pelvis, and trunk were measured before and after the retraining program, at comfortable and high speeds. A 3 × 2 mixed ANOVA revealed that BAR and CAD groups increased knee and hip flexion at footstrike, increased peak hip flexion during stance and flight phase, decreased peak hip extension during flight phase, and increased anterior pelvic tilt at both speeds after retraining. In addition, BAR increased ankle plantar flexion at footstrike and increased anterior trunk tilt. Both retraining programs demonstrated significant moderate to large effect size changes in parameters that could reduce the mechanical risks of injury associated with excessive knee stress, which is of interest to coaches, runners and those prescribing rehabilitation and injury prevention programs.

Can 16 Minutes of HIIT Improve Attentional Resources in Young Students?

Attentional resources are a cornerstone of both cognitive and academic performance. The purpose of this study was to analyse the effect of high-intensity interval training (HIIT) sessions on selective attention and visuoperceptual ability in young students. A total of 134 students (12.83 ± 1.23 years) joined this study. They were randomly assigned to a control group (CG) (n = 67), which watched a documentary, or an experimental group (EG) (n = 67), which performed 16 min of HIIT. Attention and visuoperceptual ability were assessed through the Perception of Similarities and Differences test (Caras-R test). A repeated-measures two-way ANOVA analysis was conducted. The CG showed an increased number of errors compared to the EG (p < 0.001) and showed a lower Impulsivity Control Index (p < 0.001) after the investigation. The EG, meanwhile, showed an increased number of hits (p < 0.001), Impulsivity Control Index (p < 0.001), and attentional efficacy (p < 0.001). In addition, the EG showed a decreased number of errors (p < 0.001) and omissions (p < 0.01). In conclusion, 16 min of HIIT was time-effective in improving selective attention and visuoperceptual ability in young students. These results show the importance of physical exercise and the promotion of physical activity breaks during the academic day to improve learning processes.

Effects of a High Intensity Interval Training (HIIT) Program on Anthropomorphic and Cardiometabolic Variables in School Children with Overweight and Obesity.

The aim of this study was to assess the effects of a high intensity interval training (HIIT) program on anthropomorphic and cardiometabolic variables in schoolchildren with overweight and obesity. A total of 443 schoolchildren (age: 6.37 ± 0.65 years) took part in this study. The experimental group (EG; n = 295; age = 6.40 ± 0.64 years) was compound with children with overweight and obesity, whereas children with normoweight were included in the control group (CG; n = 148; 6.31 ± 0.67 years). The EG performed a training program based on HIIT two times per week for 28 weeks (56 sessions), whilst the CG performed their habitual physical education classes based on the national curriculum. Body mass index (BMI), waist circumference, body fat, ∑ 4 skinfold fat, waist to height ratio, waist circumference, and cardiometabolic risk were measured. The dependent variables were analysed by two-way analysis of covariance (ANCOVA 2 × 2). To analyse the percentage differences between groups, the chi-square test was used. P-value was set at p < 0.05. Significant differences were found in the EG in BMI, waist circumference, body fat, ∑ 4 skinfold fat, and waist to height ratio. In conclusion, an HIIT training program can be an effective tool for improving anthropomorphic variables and reducing cardiometabolic risk in schoolchildren with overweight and obesity.

Protective role of physical activity patterns prior to COVID-19 confinement with the severity/duration of respiratory pathologies consistent with COVID-19 symptoms in Spanish populations.

The main purpose of the present study was to determine the association of physical activity (PA) patterns prior to COVID-19 confinement with severe respiratory distress consistent with COVID-19 symptoms. Participants were recruited by sending a survey through various social network channels via the snowball method. A voluntary sample of 420 individuals consisting of 199 men and 221 women from the Spanish national territory participated in this study. Some factors, such as being overweight and obese were related to the presence of a greater number of symptoms associated with COVID-19. Interestingly, it was observed that not performing moderate or vigorous PA increased the risk of COVID-19 symptoms. Consequently, when the effect of the practise of PA was evaluated in terms of the number of practises per week and in minutes per practise per week, a protective effect was observed, where moderate PA >150 min per week reported an inverse association with hospitalization for respiratory symptoms (RR: 95%CI: 0.24, 0.05-1.04, P = 0.05). Likewise, overweight (RR: 16.3, 95%CI: 1.93-137.9, P = 0.01), obesity (RR: 19.1, 95%CI: 1.63-222.5, P = 0.019) and non-performance of moderate PA (RR: 4.12, 95%CI; 0.95-17.76, P = 0.05) reported positive associations with hospitalization for respiratory symptoms. Thus, the practise of moderate PA (>150 min per week) is a protective factor against hospitalization for respiratory symptoms consistent with COVID-19 symptoms.

Effect of Exercise Intensity on Psychomotor Vigilance During an Incremental Endurance Exercise in Under-19 Soccer Players.

The aim of this study was to analyze the acute effects of an incremental resistance test on psychomotor vigilance in 16 soccer players under-19 years old (age 16.42 ± 0.85 years). Borg 15-point subjective perception of effort scale, the psychomotor vigilance task test, and the Yo-Yo intermittent recovery test were used. Four evaluation sessions were conducted with different intensities of efforts (30%-40%, 60%-75%, 80%-90%, and 100%) on different days (counterbalanced order). A repeated-measures analysis of variance was performed in the reaction time of the psychomotor vigilance task. The results showed that participants responded faster during efforts between 80% and 90% of maximal oxygen uptake (501.20 ± 70.77 ms). From that threshold, the players decreased their performance through a longer reaction time (601.23 ± 85.05 ms; p value < .001). The main findings were that the reaction time performance was worse at the lowest and highest effort conditions (5 and 17 km/hr, respectively). This fact helps to focus on the importance of designing and proposing training tasks with medium-high efforts to provoke optimal reaction times in young soccer players.

Reference Values of Spatial and Temporal Gait Parameters in a Contemporary Sample of Spanish Preschool Children: A Cross-Sectional Study.

The aim of this study was to analyze the influence of age and sex on kinematic gait parameters in preschool children, and derive reference values for this population. A total of 383 preschool children (age 3-5 years; 207 girls, 176 boys) participated in this study. We used the OptoGait system to assess the kinematics of gait at a comfortable and self-determined speed. No significant differences between the sexes were found for the main gait parameters. Among the participants, there was a significant increase in double support, reductions in absolute cadence and the coefficient of variation (CV) of cadence, an increase in absolute step length (SL), and an increase in the walk ratio (WR) from 3 to 5 years of age. However, the normalized SL and normalized WR displayed a significant reduction in both sexes. Partial correlation indicated a significant association of age with SL and normalized SL, and WR. Additionally, WR showed a significant correlation with the CV of cadence. To summarize, no relevant differences in gait performance were found according to sex; however, age was found to influence gait maturation. The normative values established for Spanish preschool children can be used to monitor healthy gait development.

Cardiac Evaluation of Exercise Testing in a Contemporary Population of Preschool Children: A New Approach Providing Reference Values.

The objective of this study was to evaluate cardiac autonomic function at rest, during maximal exercise, and in post-exercise recovery, to determine sex-specific and age-specific differences in resting heart rate (RHR), linear and spectral parameters of Heart Rate Variability (HRV), HRpeak, and heart rate recovery (HRR) after one and five minutes, in preschool children. This study involved a cohort of 167 healthy children (79 girls) aged 3 to 6 years that were selected from several schools in southern Spain. A 10 × 20 m test was conducted, and the cardiovascular response was recorded. No significant differences were found in all variables between the sexes. However, a significant reduction in RHR and an increase in HRR were found from age 4 to age 6. HRV parameters at rest were higher in older children. No associations between 10 × 20 m performance, weight status, and cardiac parameters were found. Simple linear regression analysis revealed that heart rate reserve (HRr), HRR5min, RMSSD, and HF were the variables that showed association with all HR parameters. There was also a significant correlation between HRr and HRR5min. In conclusion, cardiovascular autonomic function during rest, exercise, and recovery in Spanish preschool children was not influenced by sex, although older children showed greater cardiovascular modulation. Cardiorespiratory fitness status was not associated with HR response.

Healthy lifestyles and physical fitness are associated with abdominal obesity among Latin-American and Spanish preschool children: A cross-cultural study.

BACKGROUND: Identifying environmental factors that influence health in children are necessary to develop preventive strategies. OBJECTIVE: To determine the association between the lifestyles of children (i.e., Mediterranean diet (MD), physical activity (PA), fitness and screen time (ST) with abdominal obesity (AO) of preschoolers from three Spanish-speaking countries (Chile, Colombia and Spain) with different socioeconomic levels and Human Development Index (HDI) indicators. MATERIAL AND METHODS: This cross-sectional study included 982 schoolchildren (aged 4-6 years; 56.8% girls) from Chile (n = 409), Colombia (n = 281), and Spain (n = 292). Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WtHR), adherence to the MD, PA, ST and physical fitness were evaluated. RESULTS: Spanish preschoolers reported a lower WtHR (p < 0.001), greater physical fitness (Z-score) (p < 0.001) and higher adherence to the MD (p < 0.001) than their Chilean and Colombian peers. In addition, Colombian preschoolers had a better lifestyle (PA + ST) than their Chilean and Spanish peers (p < 0.001). Chilean preschoolers reported a higher prevalence of AO than the Spanish preschoolers (65% vs. 51.9%; p = 0.001). CONCLUSION: Lifestyle had a significant association with AO among Spanish-speaking preschool children, with physical fitness especially being a relevant factor regardless of the country of origin. The findings of the current study may support the development of public guidelines focusing on healthy lifestyles in children to create effective plans that contribute to the early treatment of AO in preschool children.

Small-sided games in amateur players: rule modification with mini-goals to induce lower external load responses.

The aim of this study was to compare the acute physiological (i.e., heart rate-related variables) and neuromuscular responses (i.e., sprint and jump) and time-motion characteristics (i.e., external load variables) when modifying the game design (possession play vs. mini-goals without a goalkeeper) during 4-a-side in amateur senior football players. Male senior football players (n = 16) performed two formats of small-sided games (SSGs) in two different testing sessions (4-a-side with possession play and mini-goals rule). Differences in time-motion characteristics and physiological parameters of players were measured with the Global Positioning System (GPS), and tested before and after (pre- and post-SSG) for neuromuscular assessment. A repeated measures analysis of variance (ANOVA), with Bonferroni post-hoc test, showed that both SSG formats induced changes in sprint performance (before-after comparison) (p ≤ 0.05). Moreover, the results showed that the variables muscle oxygen saturation, rate of perceived exertion, 85-89% heart rate peak, total distance, total distances at low speed, total distances at high speed, m/min, accelerations at low speed, accelerations of ≥ 2.5 m.s-2, maximal speed, and average speed were statistically significantly different among game conditions. The players' performances are affected by the inclusion of mini-goals during 4 vs. 4 SSGs. The results provide useful information for training and task design that replicate specific physical demands (i.e., accelerations of ≥ 2.5 m.s-2, total distances at high speed or total distances at low speed).

Is the Xiaomi Mi Band 4 an Accuracy Tool for Measuring Health-Related Parameters in Adults and Older People? An Original Validation Study.

BACKGROUND: The aim of this study was to analyse the validity and accuracy of the low-cost Xiaomi Mi Band 4 (MB4) fitness tracker in relation to step count and heart rate in free-living conditions. METHODS: 46 participants join in this study (38.65 ± 14.36 years old). The MB4 was compared with a video recording in laboratory conditions, also with the Sense Wear and Firstbeat monitors in free-living conditions. RESULTS: No significant differences were found in the number of steps in the laboratory protocol between devices, in both, at low and high walking speed. For the free-living conditions, the MB4 showed high values of convergent validity in relation to the Firstbeat monitor during recording in both rest and walking situations. Moreover, the MB4 showed adequate values of convergent validity with the Sense Wear monitor during the 24 h recording, at medium speeds, and climbing stairs. CONCLUSION: The accuracy and precision of the MB4 is reasonable and can be used to monitor the average of step count and heart rate in free-living conditions.

The effect of two retraining programs, barefoot running vs increasing cadence, on kinematic parameters: A randomized controlled trial.

The aim of this study was to compare the effects of two 10-week non-laboratory-based running retraining programs on foot kinematics and spatiotemporal parameters in recreational runners. One hundred and three recreational runners (30 ± 7.2 years old, 39% females) were randomly assigned to either: a barefoot retraining group (BAR) with 3 sessions/week over 10 weeks, a cadence retraining group (CAD) who increased cadence by 10% again with 3 sessions/week over 10 weeks and a control group (CON) who did not perform any retraining. The footstrike pattern, footstrike angle (FSA), and spatial-temporal variables at comfortable and high speeds were measured using 2D/3D photogrammetry and a floor-based photocell system. A 3 × 2 ANOVA was used to compare between the groups and 2 time points. The FSA significantly reduced at the comfortable speed by 5.81° for BAR (p < 0.001; Cohen's d = 0.749) and 4.81° for CAD (p = 0.002; Cohen's d = 0.638), and at high speed by 6.54° for BAR (p < 0.001; Cohen's d = 0.753) and by 4.71° for CAD (p = 0.001; Cohen's d = 0.623). The cadence significantly increased by 2% in the CAD group (p = 0.015; Cohen's d = 0.344) at comfortable speed and the BAR group showed a 1.7% increase at high speed. BAR and CAD retraining programs showed a moderate effect for reducing FSA and rearfoot prevalence, and a small effect for increasing cadence. Both offer low-cost and feasible tools for gait modification within recreational runners in clinical scenarios.

The Effects of Two Different Concurrent Training Configurations on Markers of Metabolic Syndrome and Fitness in Women With Severe/Morbid Obesity: A Randomised Controlled Trial.

Concurrent training (CT), characterised by combining both aerobic and resistance training modalities within the same session, is recognised to improve metabolic syndrome (MetS) markers, but little is known about the effects of different configurations (i.e., order) of these exercise modalities on MetS markers and the interindividual responses. The purpose of the present study was to describe the effects, and the interindividual variability, of 20weeks of two CT configurations (i.e., high intensity interval training (HIIT) plus resistance training (RT), compared with RT plus HIIT) in women with severe/morbid obesity. Overall, 26 women with severe/morbid obesity were assigned either to HIIT+RT [n=14, mean and 95%CI, 45.79 (40.74; 50.83) or RT+HIIT (n=12), 33.6 (25.30; 41.79) years]. MetS-related outcomes were waist circumference (WC, cm), systolic (SBP, mmHg) and diastolic (DBP, mmHg) blood pressure, high-density lipoprotein cholesterol (HDL-c), triglycerides (Tg), and fasting plasma glucose (FPG). Secondary outcomes were other anthropometrics, body composition, lipids, muscle strength, and the six-minute walk test (6Mwt). There were significant differences in the prevalence of nonresponders (NRs) only for WC comparing HIIT+RT 2 (18.1%) vs. RT+HIIT group 5 (50.0%), p<0.0001, but not for SBP 4 (27.2%) vs. 4 (40.0%), DBP 8 (72.7%) vs. 7 (70.0%), FPG 8 (72.7%) vs. 9 (90.0%), HDL-c 7 (63.6%) vs. 8 (80.0%), and Tg 7 (63.6%) vs. 8 (80.0%), all p>0.05. Additionally, the RT+HIIT group showed significant reductions in WC (∆ -3.84cm, p=0.015), SBP (∆ -8.46mmHg, p=0.040), whereas the HIIT+RT group elicited significant reductions only in SBP (∆ -8.43mmHg, p=0.022). The HIIT+RT promoted a lower prevalence of NRs than the RT+HIIT configuration on WC, and overall, there were slightly more beneficial training-induced effects on markers of MetS in the RT+HIIT group compared to the HIIT+RT group.

Selective Attention and Concentration Are Related to Lifestyle in Chilean Schoolchildren.

The objective of this investigation was to determine the association between selective attention and concentration with physical fitness (i.e., cardiorespiratory fitness (CRF), V˙O2max, the standing long jump test (SLJ) and handgrip muscle strength (HGS)), lifestyle parameters (i.e., physical activity (PA) level, screen time (ST), sleep duration and food habits) and anthropometric measures (i.e., body mass index (BMI) and waist circumference (WC)) among Chilean schoolchildren. Two hundred and forty-eight schoolchildren (137 boys, 111 girls, 11.80 ± 1.17 and 11.58 ± 1.09 years, respectively) participated. Selective attention, concentration and lifestyle (PA, ST, sleep duration and Mediterranean diet (MD) adherence) were determined using a standard questionnaire. CRF, SLJ, HGS and anthropometric indicators (BMI and WC) were also measured. Selective attention showed a positive association with MD adherence score (ß; 5.012, p = p < 0.05). Concentration was linked inversely to ST (ß; -5.498, p = p < 0.05). Likewise, concentration presented a positive association with MD adherence (ß; 2.904, p = p < 0.05). In conclusion, children's lifestyles are related to the selective attention and concentration of children; therefore, promoting healthy habits could be a cost-effective strategy in the promotion of cognitive development, as it relates to selective attention and concentration.

Association between the Sociodemographic Characteristics of Parents with Health-Related and Lifestyle Markers of Children in Three Different Spanish-Speaking Countries: An Inter-Continental Study at OECD Country Level.

The purpose of this cross-cultural study was to determine the association between the sociodemographic background of a child's parents (i.e., their socioeconomic level, marital status, and educational level) with the child's lifestyle (i.e., Mediterranean diet (MD), physical activity (PA) and screen time (ST)), and health markers. Material: This cross-sectional study included 1273 children, from Chile (n = 496), Colombia (n = 340), and Spain (n = 437). The sociodemographic information together with the lifestyle and health markers of the children were measured. There was an inverse association between a low or medium-low socioeconomic level for the parents of Chilean children and handgrip strength (ß -0.61, p < 0.001); meanwhile, for Spanish children, an inverse association between a low or medium-low socioeconomic level and PA after school (ß -0.58, p = 0.016), lifestyle (ß -0.74, p = 0.015), and with MD adherence (ß -0.86, p = 0.004) was found. The risk (i.e., by odd ratios (OR)) of being divorced/separated parents marital status showed an inverse association with abdominal obesity (OR 0.21, p = 0.045) in Spanish children; however, the parent's marital status and a low educational level were risk factors for the suffering of a low nutritional level in Colombian children (OR 2.02, p = 0.048; OR 2.49, p < 0.001, respectively). On the other hand, a low educational level for parents reported for Chilean children had a positive association with ST of ≥4 h per day (OR 1.82, p = 0.020). In conclusion, in Spanish-speaking children, the lifestyle and health markers of the children are affected by the sociodemographic background of their parents; however, these effects could be moderated by the socio-cultural and economic status of their countries as members of the OCDE; therefore, it is essential to develop policies that decrease these gaps, so that children who are under-resourced can reach their full potential.

A Randomized Controlled Trial Protocol to Test the Efficacy of a Dual-Task Multicomponent Exercise Program vs. a Simple Program on Cognitive and Fitness Performance in Elderly People.

BACKGROUND: The necessity of improve the life quality in elderly people is well-known. The aim of this study was to determine the effects of physical and cognitive training programs, as well as their combination on the cognitive functions and physical capacities in women over 80 years old. METHODS: Forty-three women took part in this study (80.86 ± 5.03 years). They were divided into four groups (three experimental groups and one control group). Experimental group 1 performed cognitive training. Experimental group 2 did physical-cognitive training, and Experimental Group 3 accomplished physical training. All of training programs had duration of eight weeks (five sessions of 60 min per week). We measured cognitive variables with the Stroop test, D2 test, and Trail Making test. Physical variables were measured with handgrip strength, Minute Step Test, and visual-acoustic reaction time. RESULTS: Control group reduces his physical and cognitive capacities, while the three experimental groups increase these capacities. We found a strong correlation between the increase of physical and cognitive capacities. CONCLUSION: Eight weeks of training physical, cognitive or mixed, increased physical and cognitive functions of elderly people which may reduce the negative effects of the aging process.

Does Arch Stiffness Influence Running Spatiotemporal Parameters? An Analysis of the Relationship between Influencing Factors on Running Performance.

This study aimed to determine the influence of arch stiffness on running spatiotemporal parameters at a common speed for a wide range of endurance runners (i.e., 12 km·h-1). In total, 97 runners, 52 men and 45 women, completed a treadmill running protocol at 12 km·h-1. Spatiotemporal parameters were measured using the OptoGait system, and foot structure was assessed by determining arch stiffness. Since between-sex differences were found in anthropometric and foot structure variables, data analysis was conducted separately for men and women, and body mass and height were considered as covariates. For both sexes, a k-means cluster analysis grouped participants according to arch stiffness, by obtaining a group of low-arch stiffness (LAS group) and a group of high-arch stiffness (HAS group), with significant differences in arch stiffness (p < 0.001, for both men and women). No significant differences between LAS and HAS groups were found in running spatiotemporal parameters, regardless of sex (p ≥ 0.05). For both sexes, the partial correlation analysis reported no significant correlations (p ≥ 0.05) between foot structure variables and running spatiotemporal parameters. The results obtained show no differences in spatiotemporal gait characteristics during running at submaximal velocity between runners with low-arch stiffness and those with high-arch stiffness, regardless of sex. These findings may have important implications for clinicians and coaches by adding more evidence to the debate about the use of static foot classification measures when characterizing the foot and its biomechanics during running.

Gait Performance as an Indicator of Cognitive Deficit in Older People.

BACKGROUND: The purpose of this study was to analyze which gait variables are the best for detecting cognitive impairment and to determine if age and gender can influence gait variations in older people. METHODS: 65 participants took part in this study (22 men and 43 women; age: 73.88 ± 9.56 years). We use the Montreal Cognitive Assessment (MoCA) to assess mild cognitive impairment (MCI). Gait speed (GS) and the complex gait test (CGT) were analyzed with photocells Witty (Microgate, Italia). The OptoGait system (Microgate, Italia) was used to analyze step length (SL) and step coefficient of variation (CV sl). RESULTS: There was a significant association between MoCA and SL (r = 0.420; p = 0.002), CV sl (r = -0.591; p < 0.001), and CGT (r = -0.406; p = 0.001). Instrumental activities of daily living showed significant association with SL (r = 0.563; p < 0.001); CV sl (r = -0.762; p < 0.001), CGT (r = -0.622; p < 0.001), and GS (r = 0.418; p < 0.001). CV sl showed the best results with MoCA when linear regression analysis was applied (R2 = 0.560; p = 0.007; Y = 23.669 - 0.320x). Participants older than 79 years showed lower MoCA scores and poorer gait parameters than people younger than 79 years. CONCLUSIONS: CV sl, SL, CGT, and GS make it possible to detect MCI in older people, especially when these variables are evaluated as a whole.

Physical Activity, Mental Health and Consumption of Medications in Pre-Elderly People: The National Health Survey 2017.

Background: The promotion of Physical Activity (PA) is an important public health goal to reduce comorbidity and diseases associated with aging such as anxiety and depression. Aim: To investigate the association between level of PA, mental health and the consumption of medications among a representative cohort of Spanish pre-elderly people. Methods: Cross-sectional study with 5977 participants aged 50 to 64 years who participated in the National Health Survey in Spain 2017. The levels of PA were evaluated using the International Physical Activity Questionnaire and the mental conditions were measured by the Goldberg Health Questionnaire-12 (GHQ-12). The chi-square test was used for qualitative variables; Pearson's correlation was conducted between GHQ-12 score with different quantitative variables; and a logistic regression was used to determine the association between PA and mental health with the sociodemographic characteristics. Results: The participants were 51.9% women and 48.1% men with a mean age of 56.79 years, and 35.5% of participants had a low level of PA. A low level of PA was associated with cases of mental health vulnerability, anxiety and depression (in women), the consumption of more medications and greater multimorbidity. Conclusion: It is important that people reach old age with an optimal health status in order to reduce age-related disability and morbidity. More than a third of the Spanish pre-elderly do not reach the levels of PA recommended by the WHO. People who had low level of PA consumed more medications and had higher mental health vulnerability and greater multimorbidity.

Effects of a 10-week running-retraining programme on the foot strike pattern of adolescents: A longitudinal intervention study.

BACKGROUND: The purpose of this study was to analyse the effects of ten weeks of different running-retraining programmes on rearfoot strike (RFS) prevalence in adolescents. RESEARCH QUESTION: it is possible to change foot strike pattern in adolescents? METHODS: A total of 180 children (45.3% girls), aged 13-16 years, participated in this intervention study. The children were randomly assigned to one of three experimental groups (EGs) that each carried out a different retraining programme, based on running technique (n = 39), a 15% increased step frequency (SF) (n = 37) and barefoot training (n = 30), performed for three days each week. A control group (CG) (n = 43) did not perform any retraining. A 2D video-based analysis (240 Hz) was used to determine the RFS. RESULTS: At baseline, no significant differences in RFS prevalence were found between the EGs and the CG in either the left (χ2 = 2.048; p = 0.559) or the right foot (χ2 = 0.898; p = 0.825). In the post-test, no significant differences were found for the left foot (χ2 = 7.102; p = 0.069), but there were significant differences for the right foot (χ2 = 9.239; p = 0.025) were observed. In the re-test, no significant differences were found for either the left foot (χ2 = 2.665; p = 0.273) or the right foot (χ2 = 2.182; p = 0.325). In addition, no group displayed significant changes in RFS prevalence from the pre-test to the re-test. There was a trend towards a reduction in the RFS prevalence in both the increased SF group and the barefoot group. MEANING: The main finding of this study was that certain running-retraining programmes performed three times per week for ten weeks are not enough to modify the adolescent foot strike pattern (FSP).

Strength Training Habits in Amateur Endurance Runners in Spain: Influence of Athletic Level.

This study determined the strength training (ST) habits of amateur endurance runners in Spain regarding athletic level. A sixteen-item online questionnaire comprised of (i) demographic information, (ii) performance, and (iii) training contents was completed by 1179 athletes. Five group levels were determined according to the personal best times of the athletes in a 10-km trial (LG1: level group 1, 50-55 min; LG2: level group 2, 45-50 min; LG3: level group 3, 40-45 min; LG4: level group 4, 35-40 min; LG5: level group 5, 30-35 min). Most athletes (n = 735, 62.3%) perceived ST as being a key component in their training program. Resistance training (RT) was reported as a ST type used by 63.4% of the athletes, 66.9% reported using bodyweight exercises, 46.8% reported using plyometric training, 65.6% reported using uphill runs, and 17.8% reported using resisted runs. The prevalence of runners who excluded ST from their training programs decreased as the athletic performance level increased (18.2% in lower-level athletes vs. 3.0% in higher-level), while the inclusion of RT, bodyweight exercises, plyometric training, and uphill and resisted runs was more frequent within higher-level groups. Most athletes included ST using low-to-moderate loads and high a number of repetitions/sets comprised of RT, plyometric training, resisted runs, and core, respiratory, and foot muscles training.