Liane B. Azevedo

Biomechanical variables associated with Achilles tendinopathy in runners

Objective: The aim of this study was to investigate the kinetics, kinematics and muscle activity in runners with Achilles tendinopathy. Design: Case–control study. Setting: Biomechanics laboratory. Participants: 21 runners free from injury and 21 runners with Achilles tendinopathy performed 10 running trials with standardised running shoes. Injured runners were diagnosed clinically according to established diagnostic criteria. Uninjured runners had been injury-free for at least 2 years. Main outcome measurements: During each trial, kinetic and lower limb kinematic data were measured using a strain gauge force plate and six infrared cameras respectively. Electromyographic (EMG) data from six muscles (tibialis anterior (TA), peroneus longus (PE), lateral gastrocnemius (LG), rectus femoris (RF), biceps femoris (BF) and gluteus medius (GM)) were measured with a telemetric EMG system. Results: Knee range of motion (heel strike to midstance) was significantly lower in injured runners than in uninjured runners. Similarly, preactivation (integrated EMG (IEMG) in 100 ms before heel strike) of TA was lower for injured runners than uninjured runners. RF and GM IEMG activity 100 ms after heel strike was also lower in the injured group. However, impact forces were not different between the two groups. Conclusion: Altered knee kinematics and reduced muscle activity are associated with Achilles tendinopathy in runners. Rehabilitation exercises or other mechanisms (e.g. footwear) that affect kinematics and muscle activity may therefore be beneficial in the treatment of runners with Achilles tendinopathy.

Reduced Eccentric Loading of the Knee with the Pose Running Method

PURPOSE The aim of this study was to compare the biomechanical changes during natural heel-toe running with learned midfoot and Pose running. METHODS Twenty heel-toe runners were instructed in midfoot running and a novel running style in which the acromium, greater trochanter, and lateral malleolus are aligned in stance (Pose running). Clinical gait analysis was performed for each running style and the biomechanical variables compared. RESULTS In comparison with midfoot and heel-toe running Pose running was characterized by shorter stride lengths and smaller vertical oscillations of the sacrum and left heel marker. Compared with midfoot and Pose running heel-toe running was characterized by greater magnitudes and loading rates of the vertical impact force. In preparation for initial contact, the knee flexed more in Pose than in heel-toe and midfoot running. The ankle at initial contact was neutral in Pose compared with a dorsiflexed and plantarflexed position in heel-toe and midfoot running, respectively. The knee power absorption and eccentric work were significant lower (P < 0.05) in Pose than in either heel-toe or midfoot running. In contrast, there was a higher power absorption and eccentric work at the ankle in Pose compared with heel-toe and midfoot running. CONCLUSIONS Pose running was associated with shorter stride lengths, smaller vertical oscillations of the sacrum and left heel markers, a neutral ankle joint at initial contact, and lower eccentric work and power absorption at the knee than occurred in either midfoot or heel-toe running. The possibility that such gait differences could be associated with different types and frequencies of running injuries should be evaluated in controlled clinical trails.

Physical fitness and academic performance in youth: A systematic review

Physical fitness (PF) is a construct of health‐ and skill‐related attributes which have been associated with academic performance (AP) in youth. This study aimed to review the scientific evidence on the association among components of PF and AP in children and adolescents. A systematic review of articles using databases PubMed/Medline, ERIC, LILACS, SciELO, and Web of Science was undertaken. Cross‐sectional and longitudinal studies examining the association between at least one component of PF and AP in children and adolescents, published between 1990 and June 2016, were included. Independent extraction of articles was carried out by the two authors using predefined data fields. From a total of 45 studies included, 25 report a positive association between components of PF with AP and 20 describe a single association between cardiorespiratory fitness (CRF) and AP. According to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines: 12 were classified as low, 32 as medium risk, and 1 as high risk of bias. Thirty‐one studies reported a positive association between AP and CRF, six studies with muscular strength, three studies with flexibility, and seven studies reported a positive association between clustered of PF components and AP. The magnitude of the associations is weak to moderate (β = 0.10–0.42 and odds = 1.01–4.14). There is strong evidence for a positive association between CRF and cluster of PF with AP in cross‐sectional studies; and evidence from longitudinal studies for a positive association between cluster of PF and AP; the relationship between muscular strength and flexibility with AP remains uncertain.

The Effectiveness of Sedentary Behaviour Interventions for Reducing Body Mass Index in Children and Adolescents: Systematic Review and Meta-analysis

Intervention studies have been undertaken to reduce sedentary behaviour (SB) and thereby potentially ameliorate unhealthy weight gain in children and adolescents. We synthesised evidence and quantified the effects of SB interventions (single or multiple components) on body mass index (BMI) or BMI z‐score in this population. Publications up to March 2015 were located through electronic searches. Inclusion criteria were interventions targeting SB in children that had a control group and objective measures of weight and height. Mean change in BMI or BMI z‐score from baseline to post‐intervention were quantified for intervention and control groups and meta‐analyzed using a random effects model. The pooled mean reduction in BMI and BMI z‐score was significant but very small (standardized mean difference = −0.060, 95% confidence interval: −0.098 to −0.022). However, the pooled estimate was substantially greater for an overweight or obese population (standardized mean difference = −0.255, 95% confidence interval: −0.400 to −0.109). Multicomponent interventions (SB and other behaviours) delivered to children from 5 to 12 years old in a non‐educational setting appear to favour BMI reduction. In summary, SB interventions are associated with very small improvement in BMI in mixed‐weight populations. However, SB interventions should be part of multicomponent interventions for treating obese children.

Maximal and submaximal physiological responses to adaptation to deep water running.

Abstract The aim of the study was to compare physiological responses between runners adapted and not adapted to deep water running at maximal intensity and the intensity equivalent to the ventilatory threshold. Seventeen runners, either adapted (n = 10) or not adapted (n = 7) to deep water running, participated in the study. Participants in both groups undertook a maximal treadmill running and deep water running graded exercise test in which cardiorespiratory variables were measured. Interactions between adaptation (adapted vs. non-adapted) and condition (treadmill running vs. deep water running) were analysed. The main effects of adaptation and condition were also analysed in isolation. Runners adapted to deep water running experienced less of a reduction in maximum oxygen consumption ([Vdot]O2max) in deep water running compared with treadmill running than runners not adapted to deep water running. Maximal oxygen consumption, maximal heart rate, maximal ventilation, [Vdot]O2 at the ventilatory threshold, heart rate at the ventilatory threshold, and ventilation at the ventilatory threshold were significantly higher during treadmill than deep water running. Therefore, we conclude that adaptation to deep water running reduces the difference in [Vdot]O2max between the two modalities, possibly due to an increase in muscle recruitment. The results of this study support previous findings of a lower maximal and submaximal physiological response on deep water running for most of the measured parameters.

Displacing Sedentary Time: Association with Cardiovascular Disease Prevalence.

PURPOSE Isotemporal substitution analysis offers new insights for public health but has only recently been applied to sedentary behavior research. We aimed to quantify associations between the substitution of 10 min of sedentary behavior with 10 min of light physical activity (LPA) or moderate-to-vigorous physical activity (MVPA) and the prevalence of cardiovascular disease (CVD). Age was also explored as a potential effect modifier. METHODS We completed a secondary analysis of data from 1477 adults from the Health Survey for England (2008). Sedentary time, LPA, and MVPA were measured using accelerometry. We applied isotemporal models to quantify the relationship with CVD prevalence of replacing 10 min of sedentary time with equivalent amounts of LPA or MVPA. Prevalence risk ratios (RR) with 95% confidence intervals (CI) are presented, adjusted for covariates. The role of age as an effect modifier was explored via age-MVPA and age-LPA interactions. CVD was defined as per the International Classification of Diseases. RESULTS The prevalence of CVD was 24%. The RR was 0.97 (95% CI, 0.96-0.99) for LPA and 0.88 (0.81-0.96) for MVPA. Substitution of approximately 50 min of LPA would be required for an association equivalent to 10 min of MVPA. The beneficial association of MVPA was attenuated with age, with a decrease in the relative risk reduction of approximately 7% per decade. CONCLUSIONS Isotemporal substitution of sedentary time with LPA was associated with a trivial relative risk reduction for CVD, whereas the equivalent replacement with MVPA had a small beneficial relationship. With respect to CVD prevalence, MVPA might become decreasingly important in older individuals. Prospective studies are needed to investigate causality.

Intermittent fasting interventions for the treatment of overweight and obesity in adults aged 18 years and over: a systematic review and meta-analysis

Objective: To examine the effectiveness of intermittent energy restriction in the treatment for overweight and obesity in adults, when compared to usual care treatment or no treatment. Introduction: Intermittent energy restriction encompasses dietary approaches including intermittent fasting, alternate day fasting, and fasting for two days per week. Despite the recent popularity of intermittent energy restriction and associated weight loss claims, the supporting evidence base is limited. Inclusion criteria: This review included overweight or obese (BMI ≥25 kg/m2) adults (≥18 years). Intermittent energy restriction was defined as consumption of ⩽800 kcal on at least one day, but no more than six days per week. Intermittent energy restriction interventions were compared to no treatment (ad libitum diet) or usual care (continuous energy restriction ∼25% of recommended energy intake). Included interventions had a minimum duration of 12 weeks from baseline to post outcome measurements. The types of studies included were randomized and pseudo-randomized controlled trials. The primary outcome of this review was change in body weight. Secondary outcomes included: i) anthropometric outcomes (change in BMI, waist circumference, fat mass, fat free mass); ii) cardio-metabolic outcomes (change in blood glucose and insulin, lipoprotein profiles and blood pressure); and iii) lifestyle outcomes: diet, physical activity, quality of life and adverse events. Methods: A systematic search was conducted from database inception to November 2015. The following electronic databases were searched: MEDLINE, Embase, CINAHL, Cochrane Library, ClinicalTrials.gov, ISRCTN registry, and anzctr.org.au for English language published studies, protocols and trials. Two independent reviewers evaluated the methodological quality of included studies using the standardized critical appraisal instruments from the Joanna Briggs Institute. Data were extracted from papers included in the review by two independent reviewers using the standardized data extraction tool from the Joanna Briggs Institute. Effect sizes were expressed as weighted mean differences and their 95% confidence intervals were calculated for meta-analyses. Results: Six studies were included in this review. The intermittent energy restriction regimens varied across studies and included alternate day fasting, fasting for two days, and up to four days per week. The duration of studies ranged from three to 12 months. Four studies included continuous energy restriction as a comparator intervention and two studies included a no treatment control intervention. Meta-analyses showed that intermittent energy restriction was more effective than no treatment for weight loss (−4.14 kg; 95% CI −6.30 kg to −1.99 kg; p ⩽ 0.001). Although both treatment interventions achieved similar changes in body weight (approximately 7 kg), the pooled estimate for studies that investigated the effect of intermittent energy restriction in comparison to continuous energy restriction revealed no significant difference in weight loss (−1.03 kg; 95% CI −2.46 kg to 0.40 kg; p = 0.156). Conclusions: Intermittent energy restriction may be an effective strategy for the treatment of overweight and obesity. Intermittent energy restriction was comparable to continuous energy restriction for short term weight loss in overweight and obese adults. Intermittent energy restriction was shown to be more effective than no treatment, however, this should be interpreted cautiously due to the small number of studies and future research is warranted to confirm the findings of this review.

Effect of novel, school-based High-intensity Interval Training (HIT) on cardiometabolic health in adolescents: Project FFAB (Fun Fast Activity Blasts) - An exploratory controlled before-and-after trial

Background Low-volume high-intensity interval training holds promise for cardiometabolic health promotion in adolescents, but sustainable interventions must be practical and engaging. We examined the effect of a school-based multi-activity low-volume high-intensity interval training intervention on adolescents’ cardiometabolic health. Methods In an exploratory controlled before-and-after design, 101 adolescents (mean age ± standard deviation [SD] 14.0 ± 0.3 years) were recruited from four schools; two were designated as intervention sites (n = 41), and two as control (n = 60). The intervention comprised 4 to 7 repetitions of 45 s maximal effort exercise (basketball, boxing, dance and soccer drills) interspersed with 90-s rest, thrice weekly for 10 weeks. Outcomes were non-fasting blood lipids and glucose, waist circumference, high sensitivity C-reactive protein, resting blood pressure, physical activity, twenty-metre shuttle-run test performance and carotid artery intima-media thickness. The difference in the change from baseline (intervention minus control) was estimated for each outcome. Using magnitude-based inferences, we calculated the probability that the true population effect was beneficial, trivial, and harmful against a threshold for the minimum clinically important difference of 0.2 between-subject SDs. Results and Discussion Mean (± SD) attendance for the intervention (expressed as percentage of available intervention sessions [n = 30]) was 77 ± 13%. Post-intervention, there were likely beneficial effects for triglycerides (-26%; 90% confidence interval -46% to 0%), waist circumference (-3.9 cm; -6.1 cm to -1.6 cm) and moderate-to-vigorous physical activity (+16 min; -5 to 38 min), and a possibly beneficial effect for twenty-metre shuttle-run test performance (+5 shuttles; -1 to 11 shuttles) in intervention participants (vs controls). The role of elevated triglycerides and waist circumference in cardiovascular disease and metabolic syndrome development underlines the importance of our findings. We also demonstrated that school-based low-volume high-intensity interval training can be delivered as intended, thus representing a novel and scalable means of improving aspects of adolescents’ cardiometabolic health. Trial Registration ClinicalTrials.gov NCT02626767

Effect of exercise on fluoride metabolism in adult humans: a pilot study

An understanding of all aspects of fluoride metabolism is critical to identify its biological effects and avoid fluoride toxicity in humans. Fluoride metabolism and subsequently its body retention may be affected by physiological responses to acute exercise. This pilot study investigated the effect of exercise on plasma fluoride concentration, urinary fluoride excretion and fluoride renal clearance following no exercise and three exercise intensity conditions in nine healthy adults after taking a 1-mg Fluoride tablet. After no, light, moderate and vigorous exercise, respectively, the mean (SD) baseline-adjusted i) plasma fluoride concentration was 9.6(6.3), 11.4(6.3), 15.6(7.7) and 14.9(10.0) ng/ml; ii) rate of urinary fluoride excretion over 0–8 h was 46(15), 44(22), 34(17) and 36(17) μg/h; and iii) rate of fluoride renal clearance was 26.5(9.0), 27.2(30.4), 13.1(20.4) and 18.3(34.9) ml/min. The observed trend of a rise in plasma fluoride concentration and decline in rate of fluoride renal clearance with increasing exercise intensity needs to be investigated in a larger trial. This study, which provides the first data on the effect of exercise with different intensities on fluoride metabolism in humans, informs sample size planning for any subsequent definitive trial, by providing a robust estimate of the variability of the effect.

Effects of a group contingency strategy on middle school physical education students’ heart rates

The purpose of this study was to assess the effects of a dependent group contingency on eighth-grade students’ heart rates. Participants were 18 male and female students. A multielement research design was used to examine the intervention effects. The intervention consisted of: (a) teacher explanation about effort; (b) students’ suggestions to increase effort; (c) a chart posting the target heart rate zones goals; and (d) teacher prompts to remind students about their effort. Participants’ heart rates were monitored during physical education lessons. The target rate was set between 70 and 85% of the participant’s estimated maximum heart rate. The results show that participants increased their time in and above target heart rate zone from 42.1% in baseline to 62.9% during intervention. Therefore, we can conclude that the intervention was successful to increase the exercise intensity during physical education lessons.