Rachel E. Ward

The effects of high‐intensity interval training vs. moderate‐intensity continuous training on body composition in overweight and obese adults: a systematic review and meta‐analysis

The objective of this study is to compare the effects of high‐intensity interval training (HIIT) and moderate‐intensity continuous training (MICT) for improvements in body composition in overweight and obese adults.

Accuracy of step count measured by physical activity monitors: the effect of gait speed and anatomical placement site.

INTRODUCTION Consumer-based physical activity monitors (PAMs) are becoming increasingly popular, with multiple global organisations recommending physical activity levels that equate to 10,000 steps per day for optimal health. We therefore aimed to compare the step count of five PAMs to a visual step count to identify the most accurate monitors at varying gait speeds, along with the optimal anatomical placement site. METHODS Participants completed 3min on a treadmill for five speeds (5.0km/h, 6.5km/h, 8.0km/h, 10km/h, 12km/h). An Actigraph wGT3XBT-BT was placed on the waist and wrist, a FitBit One on the waist, and a Fitbit Flex, Fitbit Charge HR and Jawbone UP24 on both wrists. A video of participants lower limbs was recorded for visual count. Analyses of variance (ANOVAs) were conducted to examine the effects of gait speed and device placement site on step count accuracy. RESULTS Thirty-one participants (mean age 24.3±5.2yrs) took part. Step count error ranged from 41.3±13.8% for the wrist-worn Actigraph to only 0.04±4.3% and -0.3±4.0% for the waist-worn Fitbit One and Actigraph, respectively. Across all gait speeds, waist-worn devices achieved better accuracy than those on the wrist (p<0.001). The Jawbone was the most accurate wrist-worn consumer-based device at slower speeds (p=0.026), with the Fitbit Flex, and Fitbit Charge HR increasing in accuracy to match the Jawbone at higher speeds. CONCLUSION The accuracy and reliability of consumer-based PAMs and the Actigraph is affected by anatomical placement site and walking speed. The Fitbit One and Actigraph on the waist were the strongest performers across all speeds.

Interventions to improve fundamental motor skills in pre-school aged children: A systematic review and meta-analysis

OBJECTIVES Mastery in -fundamental motor skills (FMS) is associated with increased physical activity (PA) in school-aged children; however, there is limited research on pre-schoolers (3-5 years). We aimed to evaluate interventions for improving FMS as well as PA. DESIGN/METHODS A search of electronic databases was conducted for controlled trials using PA interventions with FMS as outcomes in healthy pre-schoolers. Standardised mean difference (SMD), 95% confidence intervals and publication bias were calculated for each outcome using Revman 5.3. RESULTS Twenty trials met inclusion criteria. In total, 4255 pre-schoolers were analysed with 854 completing a FMS intervention. Studies were categorised into three groups (i) Teacher-Led (TL)(n=13); (ii) Child-Centred (CC)(n=6) and (iii) Parent-Led (PL)(n=1). Mean age was 4.3±0.4 years, with equal gender distribution. Interventions ran for 21±17 weeks, 3±1 times per week for 35±17 minutes. TL interventions significantly improved overall FMS (SMD=0.14[0.06, 0.21]; p=0.0003), object control (SMD=0.47[0.15, 0.80]; p= 0.004), and locomotor skills (SMD=0.44[0.16, 0.73]; p=0.002), whereas CC interventions were not significant. There was a small, non-significant reduction in sedentary time (SMD=-0.35[-0.80, 0.10]; p= 0.12), and a large non-significant increase in PA (SMD=0.79[-0.83, 2.41]; p=0.34). CONCLUSION PA interventions improve FMS in pre-schoolers; however, due to limited research, more study is needed on CC interventions. Targeting FMS development in pre-schoolers may promote higher PA levels and reduce sedentary time, however more study is needed.

Intensity-dependent effects of aerobic training on pressure pain threshold in overweight men: A randomized trial

To investigate the chronic and acute effects of high‐intensity interval training (HIIT) and moderate‐intensity continuous training (MICT) on pressure pain thresholds (PPT) in overweight men.

Comparison of lower limb stiffness between male and female dancers and athletes during drop jump landings

Repetition of jumps in dance and sport training poses a potential injury risk; however, non‐contact landing injuries are more common in athletes than dancers. This study aimed to compare the lower limb stiffness characteristics of dancers and athletes during drop landings to investigate possible mechanisms of impact‐related injuries. Kinematics and kinetics were recorded as 39 elite modern and ballet dancers (19 men and 20 women) and 40 college‐level team sport athletes (20 men and 20 women) performed single‐legged drop landings from a 30‐cm platform. Vertical leg stiffness and joint stiffness of the hip, knee, and ankle were calculated using a spring‐mass model. Stiffness data, joint kinematics, and moments were compared with a group‐by‐sex 2‐way analysis of variance. Multiple linear regression was used to assess the relative contribution of hip and knee and ankle joint stiffness to variance in overall vertical leg stiffness for dancers and athletes. Dancers had lower leg (P < 0.001), knee joint (P = 0.034), and ankle joint stiffness (P = 0.043) than athletes. This was facilitated by lower knee joint moments (P = 0.012) and greater knee (P = 0.029) and ankle joint (P = 0.048) range of motion in dancers. Males had higher leg (P < 0.001) and ankle joint stiffness (P < 0.001) than females. This occurred through lower ankle range of motion (P < 0.001) and greater ankle moment (P = 0.022) compared to females. Male and female dancers demonstrated reduced lower limb stiffness compared to athletes, indicating a more pliable landing technique. Dance training techniques could potentially inform approaches to injury prevention in athletes.

Bone mineral density in pre-professional female ballet dancers: A systematic review and meta-analysis

OBJECTIVES To quantitatively compare bone mineral density (BMD) outcomes between pre-professional female adolescent ballet dancers and control populations. DESIGN Systematic review and meta-analysis. METHODS Six electronic databases and relevant journals were systematically searched up to August 2017. Included articles examined BMD in adolescent females undergoing pre-professional ballet training and healthy age-matched controls with an available English full text. Dancers were aged 15-19 years and trained in ballet at least 10h per week. BMD data were analysed via standardized mean difference to account for differences in reporting methods RESULTS: From 3984 potential articles, 8 cross-sectional studies were accepted for inclusion, which compared 293 dancers (16.9±0.8 years) to 333 controls (16.9±0.9 years). No data were available from longitudinal studies. Dancers displayed lower BMD at the radius and higher BMD at the femoral neck, femoral trochanter and Wards triangle. No significant differences were observed in the lumbar spine or tibia. The overall study quality was low and heterogeneity was present in some analyses. CONCLUSIONS This meta-analysis indicates that there may be a site-specific osteogenic effect of pre-professional classical ballet training in adolescent females, with a notable and concerning finding of reduced upper limb BMD compared to age-matched controls. Longitudinal cohort studies are required to confirm the effects of pre-professional ballet training on BMD during adolescence.

Study Protocol: The Effect of a Fundamental Motor Skills Intervention in a Preschool Setting on Fundamental Motor Skills and Physical Activity: A Cluster Randomised Controlled Trial

Fundamental motor skills (FMS) are the building blocks to specialist movements that are used throughout one’s life in all forms of physical activity (PA) and sports involvement. FMS are acquired through a combination of active play and structured exercise programs. The preschool years have been identified as the critical time to develop FMS Active children experience health benefits such as decreased systolic blood pressure, depressive symptoms, weight gain, and improved concentration, academic performance and bone mineral density. Links have been identified between FMS proficiency and increased PA levels. This study aims to develop and deliver a structured FMS program for preschool aged children (age 3-5 years) in a childcare setting and determine whether it is associated with a change in PA levels and anthropometric measures. A randomized cluster control design will be employed. PLAYFun is a 12-week, games based FMS program aimed to provide children with the chance to learn, practice and develop their FMS within a preschool setting. Participants will be recruited from 4 childcare centres and will be eligible if they are aged 3-5 years and do not have developmental delay/chronic conditions that inhibit participation in PA. Centres will be randomized using concealed allocation. The control group will continue to receive usual childcare play activities while the intervention group will receive a supervised FMS intervention 2-5 sessions/week for 30 minutes duration in addition to usual childcare activities. Outcome measures will be measured pre-, post and 12-weeks post intervention. Intention to treat analysis will be used and effects on the primary outcomes will be calculated by difference between mean group scores accounting for baseline scores. The authors believe the childcare setting may provide the ideal environment to emphasize the development of movement patterns that will be used throughout life and potentially enhance participation in physical activity.

Reply to letter to the editor: high-intensity interval training vs. moderate-intensity continuous training: the lack of equalization, an ongoing problem: Letter to the Editor

We wish to thankMr Andreato and colleagues for their considered and insightful comments to our systematic review and meta-analysis. Our study focussed specifically on evaluating the relative merits of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) for improving body composition outcomes in overweight or obese, otherwise healthy individuals (1). We did not attempt to analyse each group’s effectiveness in relation to a non-exercising control group, nor analyse the training’s effectiveness in other populations (e.g. healthy normal weight individuals and chronic illness populations). We note that another recent meta-analysis published by Obesity Reviews has also compared the relative merits of these training programs but across a wider population base including healthy normal weight individuals, overweight and obese individuals and selected chronic illness populations (2). Both studies revealed broadly the same findings – HIIT and MICT appear to show similar, modest effectiveness for improving body fat levels. However, as Andreato and colleagues stated, it is important that we must be careful when interpreting these findings due to the need to stringently take into account studies that did not apply training protocols that were matched for total workload or oxygen consumption. We did not provide a sub-analysis comparing data from studies with matched protocols (N = 7 studies (3–9)) vs. unmatched protocols (N = 6 studies (10–15)) in our initial publication, and we agree this is a limitation. The unmatched studies invariably involved HIIT participants performing less total work than the MICT participants. We have since conducted a sub-analysis comparing our matched vs. unmatched studies. Our data show that our inclusion of six studies that involved unmatched training protocols for workload or oxygen consumption did not meaningfully influence the between-group standardized mean difference (SMD) comparisons (body mass – matched studies SMD = 0.06; unmatched studies SMD = 0.15; for body fat mass in kilograms – matched studies SMD = 0.07; unmatched studies SMD = 0.10, where positive numbers indicate a greater effect in MICT group compared with HIIT group). In contrast, while Keating et al. (2) report no significant differences in body composition outcomes between HIIT and MICT for studies involving matched protocols, the authors noted that HIIT protocols that involved lower time commitment or energy expenditure than MICT did tend to show less effectiveness for improving total body fat percentage (p = 0.09). There are two caveats to that point. Firstly, the finding was not supported for the measure of body fat mass in kilograms (p = 0.56). Secondly, matching groups by time commitment is problematic, because the main ‘selling’ point for wide-spread application of HIIT is its relative time-efficiency compared with MICT (16). Ideally, HIIT vs. MICT comparison studies need to involve less time commitment for the HIIT participants, with groups matched by total workload (Nm; easy to calculate in cycling studies) or, when workload cannot be accurately calculated (e.g. running studies), by total oxygen consumption (L O2). Matching groups by total energy expenditure, when total workload cannot be accurately calculated, is also flawed. For MICT sessions, an estimate of energy expenditure can be derived reasonably well, predominantly by applying a standard factor (typically 21 kilojoules per litre of O2 min 1 reflecting fat and carbohydrate oxidation rates) to the oxygen consumption values. This relationship is less accurate for HIIT sessions, and even less accurate again for sprint interval training, where a larger proportion of energy is drawn from glycolysis and ATP–PCr reactions. We also broadly agree with Andreato and colleagues that interpreting the clinical relevance of the data from our subanalysis comparing the effect of running and cycling studies on body composition is difficult due to the equalization issues that were raised. We reported a rather large effect of running training on body composition outcomes (SMD ~0.8) but not so for the cycling studies (SMD ~0.2), which was an intriguing finding. We appreciate Andreato and colleagues for noting that this is largely explained by the vast mismatch across the studies – the running studies appeared to involve much greater training volume than the cycling studies. Analysis of this data has shown that total exercise time for HIIT participants in running studies was 107% higher than in cycling studies (running: N = 6 studies, 1471 ± 1108 min vs. cycling: N = 7 studies, obesity reviews doi: 10.1111/obr.12586