Drivers of adolescent adiposity: Evidence from the Australian LOOK study

ObjectivesTo contribute to our understanding of the drivers of body composition during adolescence we sought to employ valid and reliable measures to investigate cross-sectional and longitudinal relationships between percentage body fat (%BF) and physical activity (PA), moderate and vigorous PA (MVPA), sedentary time (ST), total energy, sugar and fat intake.DesignLongitudinal cohort study.MethodsWe measured 556 (289 male) participants at age 12.4 (SD 0.4) years, and 269 (123 males) at 16.3 (SD 0.4) years, for %BF (dual energy X-ray absorptiometry); habitual PA, MVPA, ST (accelerometry); and dietary intake (‘multi-pass’ weekday and weekend 24-h recall). Accounting for likely under-reporting of energy intake (Goldberg cut-off), general linear mixed modelling was used to generate relationships with %BF.ResultsCross-sectional analyses indicated that 10 min more MVPA per day was associated with 0.6 lower %BF (95%CI 0.4–0.9, p < 0.001), and 10 min less ST/day with 0.07 lower %BF (95%CI 0.00–0.15, p < 0.001), independently of PA. In contrast, %BF was unrelated to total energy (p = 0.4), sugar intake (p = 0.2) or fat intake (p = 0.9). Longitudinal analysis showed that if PA was increased by 3% (10,000 counts/day) over the 4 years, then %BF was reduced by 0.08 (95%CI 0.05–0.12, p = 0.06).ConclusionsThe independent relationships of %BF with PA and ST, but absence of relationships with energy, sugar or fat intake, suggest that general community campaigns in a developed country directed at reducing adolescent obesity through modifications to energy intake and output would benefit from a more concerted focus on the latter.     

Injury epidemiology in Australian male professional soccer

ObjectivesTo describe the injury epidemiology of the Australian male professional soccer league (A-League) over 6 consecutive seasons.DesignProspective observational cohort study.MethodsMatch-loss injury data was collected from each A-League club (n = 10) for each competition match (n = 27/season) over 6 seasons (2012/13–2017/18). Injuries were collected weekly through a standardised protocol and were classified by setting, mechanism, severity, the type and location on the body. Generalised Linear Models were used to estimate the injury incidences (injury/round/season), whilst rate ratios were reported for total injuries and within abovementioned injury classifications.ResultsOverall injury incidence was not significantly different ranging from 4.8 (95%CI:4.1–5.8) to 6.7 (95%CI:5.8–7.8) between seasons 2012/13 to 2017/18 (p > 0.05). Match injuries remained stable whilst training injuries decreased across the 6 seasons (exp(β) 0.59[95%CI:0.36–1.0]; p = 0.04). Respectively, contact and non-contact injuries were not significantly different across the 6 seasons, although non-contact injuries were more common than contact injuries (p > 0.05). Mild severity injuries decreased (exp(β) 0.64 [95%CI:0.4–0.9];p = 0.02), whilst moderate severity injuries increased (exp(β) 1.7 [95%CI:1.0–2.8];p = 0.04) in season 2017/18 compared to 2012/13. The most common injuries were at thigh (23–36%), of which the majority were hamstring injuries (54%–65%) of muscle/tendon type (50–60% of total injuries/season). Injuries remained stable across the seasons by type and location (p > 0.05 and p > 0.05, respectively).ConclusionsInjury rates, mechanisms, locations and types have remained relatively stable over recent seasons of the A-League. Current Australian professional soccer league medical practices may have contributed to the stability of injury rates.     

Sleep duration and quality are associated with nutrient intake in elite female athletes

ObjectivesSleep is important for athlete health and performance; however, the relationship between diet and sleep in elite female athletes is not well understood. This study examined associations between energy, macronutrient and micronutrient intakes, and sleep in elite female Australian footballers.DesignProspective cohort study.MethodsThirty-two players had their diet and sleep monitored for 10 consecutive days during pre-season. Sleep was monitored using activity monitors and sleep diaries. Sleep outcomes included sleep duration, sleep onset latency (SOL), wake time after sleep onset (WASO), and sleep efficiency (SE). Dietary intake was monitored using the smartphone applications Easy Diet Diary and FoodWorks. Relationships between nutrient intake and sleep were assessed using Generalised Estimating Equations.ResultsFor each 1-g·kg^?1 increase in carbohydrate intake, WASO increased by 3.6 min (p = 0.007) and SE decreased by 0.6% (p = 0.007). For each 1-g increase in daily saturated fat intake, SOL decreased by 0.27 min (p = 0.030). For each 1-mg increase in iron intake, sleep duration increased by 0.55 min (p < 0.001). For each 1-mg increase in zinc intake, SE increased by 0.23% (p = 0.006). For each 1-μg increase in vitamin B12 intake, WASO decreased by 1.72 min (p < 0.02) and SE increased by 0.40% (p = 0.033).ConclusionsNutrient intake in elite female athletes is associated with sleep and may contribute to sleep problems. Research should explore causal relationships between nutrient intake and sleep, and the efficacy of dietary interventions for improving sleep in female athletes with nutrient deficiencies.     

Physical fitness predicts adiposity longitudinal changes over childhood and adolescence

ObjectivesThe purpose of this study was to examine the influence of physical fitness (PF) on the development of subcutaneous adipose tissue in children followed longitudinally over a 9 year period ranging from childhood to adolescence.DesignThis longitudinal study followed 518 healthy participants (262 boys, 256 girls) over a 9-year period ranging from childhood (age 6) to adolescence (age 15). Adiposity (triceps and subscapular skinfolds), and fitness (60 s sit-ups, flexed arm hang, standing long jump, 50 m dash, 10 m shuttle run, sit-and-reach, and 20 m pacer run) were assessed at four annual time points during primary school, and on a follow up, 6 years later, during secondary school.MethodsGrowth in subcutaneous fat was modeled within a HLM statistical framework, using fitness components as time changing predictors.ResultsFlexed arm hang (β = ?0.059; p = 0.000), standing long jump (β = ?0.072; p = 0.000), 60 s sit-ups (β = ?0.041; p = 0.040), 50 m dash (β = 0.956; p = 0.000), and 20 m PACER (β = ?0.077; p = 0.000) tests, were found to predict changes on body fat growth over the years, independently of sex.ConclusionsImproving PF individual levels can positively influence adiposity deposition over the time period covering childhood and adolescence. That occurs independently of the typical sex differentiated adiposity growth.     

Fitness,waist circumference and their association with future blood pressure in youth: The UP&DOWN Longitudinal Study

ObjectivesThe aim was to determine the independent associations of muscular fitness (MF), cardiorespiratory fitness (CRF) and waist circumference (WC) with blood pressure (BP) levels over 2 years in children and adolescents.Methods1089 children (517 females) and 787 adolescents (378 females) with complete data on fitness, WC and BP (systolic [SBP] and diastolic [DBP]) were included. Upper MF was assessed through the handgrip strength test, and lower MF using the standing long jump test. The 20-m shuttle run test was used to assess CRF. WC was obtained following standardized methods. Different regression models were fitted by introducing fitness and WC at baseline and their changes as exposures and BP at follow-up and their changes as outcomes.ResultsWC at baseline was positively and independently associated with each BP variable at follow-up in children and adolescents (β = 0.094–0.260; p ≤ 0.05), and CRF was negatively associated with DBP in adolescents (β = ?0.096; p = 0.034). WC changes were associated with BP variables 2 years later in children (β = 0.121–0.142; p < 0.01). In adolescents, changes in upper MF (β = ?0.116; p = 0.001) and WC (β = 0.080–0.098; p < 0.05) were associated with SBP at follow-up. WC changes were independently associated with changes in each BP variable in children (β = 0.111–0.145; all p < 0.05) and SBP changes in adolescents (β = 0.103 to 0.117; all p < 0.01).ConclusionsWC, but neither MF nor CRF, is independently associated with BP and its changes over 2 years. The attainment or maintenance of optimal fatness levels in the pediatric population should be highly encouraged for the prevention of future hypertension.     

The use of the dual-task paradigm in detecting gait performance deficits following a sports-related concussion: A systematic review and meta-analysis

ObjectivesThe purpose of this systematic review was to determine the viability of the dual-task paradigm in the evaluation of a sports-related concussion.DesignSystematic review and meta-analysis.MethodsEight electronic databases were searched from their inception until the 11^th of April 2011. Studies were grouped according to their reported gait performance variables and their time(s) of assessment(s). Raw mean differences (MD) and 95% confidence intervals (CI) were calculated based on raw means and standard deviations for gait performance measures in both single- and dual-task conditions. Dual-task deficits were pooled using a random effects model and heterogeneity (I²) between studies was assessed.ResultsTen studies representing a total sample of 168 concussed and 167 matched (age and gender) non-concussed participants met the inclusion criteria. Meta-analysis demonstrated that dual-task performance deficits were detected (p < 0.05) in the concussed group for gait velocity (GV) (MD = ?0.133; 95% CI ?0.197, ?0.069) and range of motion of the centre of mass in the coronal plane (ML-ROM) (MD = 0.007; 95% CI 0.002, 0.011), but not in the non-concussed group; GV (MD = ?0.048; 95% CI ?0.101, 0.006), ML-ROM (MD = 0.002; 95% CI ?0.001, 0.005).ConclusionsThe results of this study indicate that GV and ML-ROM are sensitive measures of dual-task related changes in concussed patients and should be considered as part of a comprehensive assessment for a sports-related concussion.     

The effect of exercise intensity on chronic inflammation: A systematic review and meta-analysis

ObjectivesChronic inflammation is independently associated with the incidence and progression of chronic disease. Exercise has been found to reduce chronic inflammation, however the role of exercise intensity (work rate) is unknown. This review aimed to determine the pooled effect of higher- compared to lower-intensity aerobic and resistance exercise on chronic inflammation in adults.DesignSystematic review and meta-analysis.MethodsFive electronic databases were searched. Intervention trials that assessed the effect of ≥2 different exercise intensities on peripheral markers of chronic inflammation [c-reactive protein (CRP), interleukin (IL)-6, tumour necrosis factor (TNF)-α and IL-10] in adults were included. Random-effect meta-analyses were conducted to calculate the mean difference in change scores between groups [effect size (ES)]. Sub-group analyses were performed to explore the influence of age, chronic disease, body mass index and intervention duration on inflammation heterogeneity.ResultsOf 3952 studies identified, 27 were included. There were no significant effects of exercise intensity on IL-6 (ES=-0.039, 95%CI=-0.353–0.275; p = 0.806), TNF-α (ES = 0.296, 95%CI=-0.184–0.777; p = 0.227) and IL-10 (ES = 0.007, 95%CI=-0.904–0.919; p = 0.987). A significant pooled ES was observed for higher- versus lower-intensity exercise on CRP concentrations, in studies of middle-aged adults (ES=-0.412, 95%CI=-0.821– -0.004, p = 0.048) or interventions >9 weeks in duration (ES=-0.520, 95%CI=-0.882–-0.159, p = 0.005).ConclusionsExercise intensity did not influence chronic inflammatory response. However, sub-analyses suggest that higher-intensity training may be more efficacious than lower-intensity for middle-aged adults, or when longer duration interventions are implemented (>9 weeks), in the most commonly-reported analyte (CRP).     

Upper and lower trapezius muscle activity in subjects with subacromial impingement symptoms: Is there imbalance and can taping change it?

ObjectivesTo investigate (i) whether subacromial impingement symptoms (SIS) were associated with upper and lower trapezius muscle imbalance and (ii) the effect of a scapula taping technique on upper and lower trapezius muscle activity.DesignCross-sectional study with nested within-subject intervention.SettingUniversity research laboratory.ParticipantsSubjects who demonstrated SIS (n = 16) on clinical testing and an age and gender matched group of asymptomatic subjects (n = 32).Main outcome measuresSurface electromyography (EMG) to measure activity in the upper (UFT) and lower (LFT) fibres of trapezius during repeated humeral elevation in the scapular plane.ResultsSymptomatic subjects demonstrated a significantly (95% CI 2.13 to 4.17, p = 0.019) higher ratio of UFT:LFT activity than the asymptomatic subjects (95% CI 1.35 to 2.25). With tape in situ the symptomatic subjects demonstrated a significant (95% CI ?8.6% to ?17.3%, p < 0.001) reduction in UFT activity but no significant (95% CI +2.8% to ?17.5%, p = 0.145) change in activity of LFT. No relationship (r = ? 0.116, p = 0.669) was found between the degree of underlying muscle imbalance and the reduction in UFT under the taped condition for the symptomatic group.ConclusionSubacromial impingement symptoms are associated with altered upper and lower trapezius muscle activity which can be partially addressed by the application of tape.     

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

ObjectivesThis study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat.DesignRandomized, double-blind, cross-over study.MethodsTwelve men and six women (mean ± SD: Age 27 ± 6 years, height 1.76 ± 0.10 m, mass 74 ± 12 kg, V̇O_2max 53.4 ± 7.0 mL kg⁻¹ min⁻¹) completed one assessment of maximal aerobic capacity and one familiarisation trial (18 °C, 40% relative humidity, RH), before ingesting 2 × 300 mg day⁻¹ capsules of CurraNZ™ (each containing 105 mg anthocyanin) or a visually matched placebo (2 × 300 mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60 min of fasted running at 65% V̇O_2max in hot ambient conditions (34 °C and 40% relative humidity).ResultsCarbohydrate oxidation was decreased in the NZBC trial [by 0.24 g min⁻¹ (95% CI: 0.21–0.27 g min^-1)] compared to placebo (p =  0.014, d = 0.46), and fat oxidation was increased in the NZBC trial [by 0.12 g min⁻¹ (95% CI: 0.10 to 0.15 g min⁻¹)], compared to placebo (p = 0.008, d = 0.57). NZBC did not influence heart rate (p = 0.963), rectal temperature (p = 0.380), skin temperature (p = 0.955), body temperature (p = 0.214) or physiological strain index (p = 0.705) during exercise.ConclusionsSeven-days intake of 600 mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.     

Is body mass index a risk factor for sport injury in adolescents?

ObjectivesTo investigate the relationship between sport injury and body mass index in adolescents (12–19 years).DesignSecondary analysis of data collected in junior and senior high school surveys in Alberta, Canada.MethodsParticipants (n = 4339) included students from 59 schools. All sport injury was defined as injury reported in the past one year. Medically treated injury, as any more serious sport related injury reported in the last year that required medical attention. Overweight, obese, and healthy was defined using international cut points, as the exposure.ResultsMultivariate logistic regression analysis controlling for clustering by school, and adjusting for potential risk factors was used. There was a 34% increased risk for all sport injury in obese adolescents compared to healthy adolescents [odds ratio (OR) = 1.34 (95% CI: 1.02–1.80)]. There was increased risk for all sport injury and medically treated injury with hours of participation, where the highest group had a 4-fold increase in risk (OR = 4.17, 95%CI: 2.77–6.30 and OR = 3.80, 95%CI: 2.54–5.69, respectively). There was also increased risk for both all sport injury and medically treated injury in Caucasians compared to non-Caucasians [OR = 1.45 (95%CI: 1.15–1.82), OR = 1.94 (95%CI: 1.59–2.37), respectively], as well as for club/team play compared to less elite play [OR = 1.87 (95%CI: 1.43–2.44) and OR = 2.12 (95%CI: 1.57–2.87), respectively].ConclusionsThe risk of sustaining a sport injury in obese adolescents was greater compared to those of healthy weight. There is also a greater risk with increasing hours of play, in Caucasian adolescents, and those that play at a higher sporting level.     

Child,family and environmental correlates of children's motor skill proficiency

ObjectivesTo identify factors associated with children's motor skills.DesignCross-sectional.MethodsAustralian preschool-aged children were recruited in 2009 as part of a larger study. Parent proxy-report of child factors (age, sex, parent perception of child skill, participation in unstructured and structured activity), self-report of parent factors (confidence in their own skills to support child's activity, parent–child physical activity interaction, parent physical activity) and perceived environmental factors (play space visits, equipment at home) were collected. Moderate to vigorous physical activity (MVPA) (ActiGraph GT1M accelerometer) and motor skills (Test of Gross Motor Development-2) were also assessed. After age adjustment, variables were checked for association with raw object control and locomotor scores. Variables with associations of p < 0.20 were entered into two multiple regression models with locomotor/object control as respective outcome variables.ResultsMotor skills were assessed for 76 children (42 female), mean [SD] age = 4.1 [0.68]; 71 completed parent proxy-report and 53 had valid MVPA data. Child age, swimming lessons, and home equipment were positively associated explaining 20% of locomotor skill variance, but only age was significant (β = 0.36, p = 0.002). Child age and sex, unstructured activity participation, MVPA%, parent confidence, home equipment (all positively associated), and dance participation (inversely associated) explained 32% object control variance. But only age (β = 0.67, p < 0.0001), MVPA% (β = 0.37, p = 0.038) and no dance (β = ?0.34, p = 0.028) were significant.ConclusionMotor skill correlates differ according to skill category and are context specific with child level correlates appearing more important.     

Evaluation of adolescent sport specialization and injury mechanism by sex: A secondary analysis

ObjectivesThe purpose of this study was to compare the association of sport specialization with previous overuse and acute injuries between male and female adolescent athletes.DesignCross-sectional study.MethodsQuestionnaires were completed by adolescent athletes from various sports at sport club summer events in the state of Wisconsin. Adolescent athletes (12–18 years old) who were active in organized sports in the previous year were recruited. The questionnaire contained demographics, sport participation, sport specialization classification, and previous injury history. Sport specialization classification was determined using common methods in sport specialization research. Previous injury was restricted to athletic injuries that occurred in the past year.ResultsTwo-thousand and eleven participants (age = 13.7 ± 1.6 years, females = 989) completed the questionnaire. Highly specialized athletes were more likely to report both acute and overuse injuries compared to low specialization athletes. However, this relationship differed by sex, with only moderate and highly specialized females being more likely (Moderate: OR [95%CI] = 1.74 [1.18–2.58], p = 0.005; High: OR [95%CI] = 1.69 [1.14–2.53], p = 0.010) to report an overuse injury compared to low specialization females. Highly specialized female athletes were more likely to report an acute injury (High: OR [95%CI] = 1.46 [1.06–2.02], p = 0.022) compared to low specialization females. Highly specialized male athletes were not associated with overuse or acute injuries.ConclusionsHighly specialized athletes were more likely to report acute and overuse injuries. However, when this analysis was separated by sex, only highly specialized females were more likely to report a previous overuse or acute injury.     

An MRI-based dose–response analysis of urinary sphincter dose and urinary morbidity after brachytherapy for prostate cancer in a phase II prospective trial

PurposeTo compare dose–volume histogram variables for the internal and external urinary sphincters (IUS/EUS) with urinary quality of life after prostate brachytherapy.Methods and MaterialsSubjects were 42 consecutive men from a prospective study of brachytherapy as monotherapy with ¹²⁵I for intermediate-risk localized prostate cancer. No patient received hormonal therapy. Preplanning constraints included prostate V₁₀₀ higher than 95%, V₁₅₀ lower than 60%, and V₂₀₀ lower than 20% and rectal R₁₀₀ less than 1 cm³. Patients completed the Expanded Prostate Cancer Index Composite quality-of-life questionnaire before and at 1, 4, 8, and 12 months after implantation, and urinary domain scores were analyzed. All structures including the IUS and EUS were contoured on T2-weighted MRI at day 30, and doses received were calculated from identification of seeds on CT. Spearman's (nonparametric) rank correlation coefficient (ρ) was used for statistical analyses.ResultsOverall urinary morbidity was worst at 1 month after the implant. Urinary function declined when the IUS V₂₈₅ was 0.4% (ρ = ?0.32, p = 0.04); bother worsened when the IUS V₃₅ was 99% (ρ = ?0.31, p = 0.05) or the EUS V₂₄₀ was 63% (ρ = ?0.31, p = 0.05); irritation increased when the IUS V₃₅ was 95% (ρ = ?0.37, p = 0.02) and the EUS V₂₆₅ was 24% (ρ = ?0.32, p = 0.04); and urgency worsened when the IUS V₃₅ was 99.5% (ρ = ?0.38, p = 0.02). Incontinence did not correlate with EUS or IUS dose.ConclusionsDoses to the IUS and EUS on MRI/CT predicted worse urinary function, with greater bother, irritative symptoms, and urgency. Incorporating MRI-based dose–volume histogram analysis into the treatment planning process may reduce acute urinary morbidity after brachytherapy.     

Sleep quality is associated with walking under dual-task,but not single-task performance

ObjectivesThe objective of this study was to assess the relationship between sleep behavior and gait performance under single-task (ST) and dual-task (DT) walking conditions in community- dwelling older adults.MethodsWalking under ST and DT conditions was evaluated in 34 community-dwelling older adults, 64.7% women, mean age 71.5 (SD ± 5.8). Gait-speed and gait-variability data were collected using the OPAL wearable sensors of the Mobility Lab. Sleep behavior (sleep efficiency [SE] and sleep latency [SL]) was assessed using actigraphy, over 5 consecutive nights.ResultsLower SE was associated with decreased gait speed and increased stride-length variability during DT (rs = 0.35; p = 0.04; rs = −0.36; p = 0.03, respectively), whereas longer SL was associated with increased stride-length variability during DT (rs = 0.38; p = .03). After controlling for age and cognition, SE accounted for 24% and 33% of the variability in stride length and stride time. No associations were found between sleep and gait measures under ST walking.ConclusionsLower SE is associated with decreased gait speed and increased gait variability under DT conditions that are indicative of an increased risk for falls in older adults. Our findings support clinical recommendations to incorporate the evaluation of sleep quality in the context of risk assessment for falls.     

Monitoring fitness,fatigue and running performance during a pre-season training camp in elite football players

ObjectivesTo examine the usefulness of selected physiological and perceptual measures to monitor fitness, fatigue and running performance during a pre-season, 2-week training camp in eighteen professional Australian Rules Football players (21.9 ± 2.0 years).DesignObservational.MethodsTraining load, perceived ratings of wellness (e.g. fatigue, sleep quality) and salivary cortisol were collected daily. Submaximal exercise heart rate (HRex) and a vagal-related heart rate variability index (LnSD1) were also collected at the start of each training session. Yo-Yo Intermittent Recovery level 2 test (Yo-YoIR2, assessed pre-, mid- and post-camp, temperate conditions) and high-speed running distance during standardized drills (HSR, >14.4 km h^?1, 4 times throughout, outdoor) were used as performance measures.ResultsThere were significant (P < 0.001 for all) day-to-day variations in training load (coefficient of variation, CV: 66%), wellness measures (6–18%), HRex (3.3%), LnSD1 (19.0%), but not cortisol (20.0%, P = 0.60). While the overall wellness (+0.06, 90% CL (?0.14; 0.02) AU day^?1) did not change substantially throughout the camp, HRex decreased (?0.51 (?0.58; ?0.45) % day^?1), and cortisol (+0.31 (0.06; 0.57) nmol L^?1 day^?1), LnSD1 (+0.1 (0.04; 0.06) ms day^?1), Yo-YoIR2 performance (+23.7 (20.8; 26.6) m day^?1, P < 0.001), and HSR (+4.1 (1.5; 6.6) m day^?1, P < 0.001) increased. Day-to-day ΔHRex (r = 0.80, 90% CL (0.75; 0.85)), ΔLnSD1 (0.51 (r = 0.40; 0.62)) and all wellness measures (0.28 (?0.39; ?0.17) < r < 0.25 (0.14; 0.36)) were related to Δtraining load. There was however no clear relationship between Δcortisol and Δtraining load. ΔYo-YoIR2 was correlated with ΔHRex (r = 0.88 (0.84; 0.92)), ΔLnSD1 (r = 0.78 (0.67; 0.89)), Δwellness (r = 0.58 (0.41; 0.75), but not Δcortisol. ΔHSR was correlated with ΔHRex (r = ?0.27 (?0.48; ?0.06)) and Δwellness (r = 0.65 (0.49; 0.81)), but neither with ΔLnSD1 nor Δcortisol.ConclusionsTraining load, HRex and wellness measures are the best simple measures for monitoring training responses to an intensified training camp; cortisol post-exercise and LnSD1 did not show practical efficacy here.     

Sodium bicarbonate improves sprint performance in endurance cycling

ObjectivesOral sodium bicarbonate intake (NaHCO₃) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO₃ also enhances all-out performance at the end of an endurance competition. Therefore, the present study investigated the effect of stacked NaHCO₃ loading on sprint performance following a 3-h simulated cycling race.DesignDouble-blind randomized placebo-controlled cross-over study.MethodsEleven trained male cyclists (22.3 (18.3–25.3) year; 73.0 (61.5–88) kg; VO₂max: 63.7 (57–72) ml kg^?1 min^?1) ingested either 300 mg kg^?1 body weight NaHCO₃ (BIC) or NaCl (PL). NaHCO₃ or NaCl was supplemented prior to (150 mg kg^?1) and during (150 mg kg^?1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO₃^? concentrations. Analysis of variance (lactate, pH, HCO₃^?) and paired t-test (power) were applied to compare variables across condition (and time).ResultsNaHCO₃ intake improved mean power during 90S by ～3% (541 ± 59 W vs. 524 ± 57 W in PL, p = 0.047, Cohen’s D = 0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p < 0.05) in BIC (16.2 ± 4.1 mmol l ¹, 184 ± 7 bpm) than in PL (12.4 ± 4.2 mmol l^?1, 181 ± 5 bpm). NaHCO₃ ingestion increased blood [HCO₃^?] (31.5 ± 1.3 vs. 24.4 ± 1.5 mmol l^?1 in PL, p < 0.001) and blood pH (7.50 ± 0.01 vs. 7.41 ± 0.03 in PL, p < 0.05) prior to 90S.ConclusionsNaHCO₃ supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.     

Accelerometer detected lateral sway during a submaximal running test correlates with endurance exercise performance in elite Australian male cricket players

ObjectiveTo identify whether movement patterns during a standardized submaximal running test (SSRT), assessed by accelerometry, were associated with improvements in endurance exercise performance.DesignA retrospective analysis of data collected from the 2018–2019 Australian cricket preseason.MethodsThirty-nine high-performance male cricket players were studied (25 ± 3 years, 82 ± 6 kg, 183 ± 6 cm). SSRT was performed monthly prior to a two kilometre (km) running time trial (2 kmTT). SSRT involved running between markers, positioned twenty metres apart, for three minutes. Foot strikes were timed to a metronome (154 beats/min) to elicit a running speed of ˜eight km/h. Triaxial accelerometers were worn in vests on the upper back and used to assess PlayerLoad medio-lateral vector (PL1D_side%), vertical vector (PL1D_up%) and anterior-posterior vector (PL1D_fwd%) were assessed.Results2 kmTT performance improved over the study period (p < 0.05). PlayerLoad vectors during the first minute of SSRT were not related to 2 kmTT performance (p > 0.23). During the second and third minutes there were positive associations between 2 kmTT (run time) and PL1D_side% (SSRT_2min, β 2.12, p < 0.03, 95% CI: 0.22–4.01; SSRT3_min, β 2.30, p < 0.03, 95% CI:0.32–4.29), but not PL1D_up% (SSRT_2min, β −0.15, p = 0.77, 95% CI: −1.13–0.83; SSRT_3min, β −0.15, p = 0.77, 95% CI: −1.11–0.87) or PL1D_fwd% (SSRT_2min, β −0.45, p = 0.42, 95% CI: −1.49–0.62; SSRT_3min, B−0.45, p = 0.40, 95% CI: −1.51–0.60).ConclusionAssessment of PL1D_side% during the second or third minutes of SSRT may inform how an athlete’s endurance exercise performance is responding to changes in training load.     

Variability and physical demands of international seam bowlers in one-day and Twenty20 international matches across five years

ObjectivesTo quantify and compare the match demands and variability of international One-Day (ODI) with Twenty20 (T20) cricket matches and to compare ODI match demands when competing home and away.DesignSingle cohort, longitudinal observation.MethodsThirteen international male seam bowlers across 204 matches (ODI = 160; T20 = 44) were investigated over five-years (2015?2019). Using global positioning sensors and accelerometers, physical demands were quantified using distance covered at different velocities and the number of entries into high and low intensity acceleration and deceleration bands. Variability was quantified using coefficient of variation (CV) and smallest worthwhile change.ResultsSignificantly greater (p < 0.05) match demands were found for all physical variables relative to minutes played for T20 against ODI matches, except for distance covered 20?25 km h^?1 which was greater for ODI. Distance covered between 0?7 km?h^?1 showed no significance difference (p = 0.60). The number of moderate decelerations (2?4 m?s²) were greater (p = 0.04) away compared to home in ODI. All other variables showed no significance. Relative to minutes played, decelerations ≤4 m?s² (within-player ODI CV = 75.5%. T20 = 72.0%) accelerations >4 m?s² (within-player ODI CV = 79.2%. T20 CV = 77.2%. Between-player ODI CV = 84.7%. T20 = 38.8%) and distance covered >25 km h^?1 (within-player ODI CV = 65.5%. T20 = 64.1%) showed the greatest variability.ConclusionsPlayers are exposed to different physical demands in ODI Vs T20 matches, but not for home Vs away ODI matches. Practitioners should be aware of the large variability in high-speed/intensity accelerations and decelerations across matches.     

The association between multiple sclerosis-related fatigue and balance as a function of central sensory integration

BackgroundFatigue and impaired upright postural control (balance) are the two most common complaints in persons with multiple sclerosis (MS), with limited evidence on how they are related.ObjectiveTo examine the relationship between symptomatic fatigue and balance as a function of central sensory integration in persons with multiple sclerosis.Materials and methodsSeventeen persons with relapsing-remitting MS were enrolled in this cross-sectional study. Primary measurements included fatigue (modified fatigue impact scale – MFIS); balance (dynamic posturography, sensory organization testing – SOT); and walking capacity (six-minute walk test – 6MWT).ResultsFatigue scores were significantly associated with balance: MFIS total (r = ?0.78; p < 0.001), physical subscale (r = ?0.77; p < 0.001), cognitive subscale (r = ?0.75; p = 0.001) and psychosocial subscale (r = ?0.53; p = 0.030) scores. MFIS total score was a significant predictor of balance (p ≤ 0.001), accounting for 62% of the variability in SOT composite scores. Significant differences in fatigue (d = 1.75; p = 0.005) and balance (d = 1.74; p = 0.005) were found for participants who had cerebellar and brainstem involvement compared to those without.ConclusionsSymptomatic fatigue is significantly related to balance and is a significant predictor of balance as a function of central sensory integration in persons with MS. Fatigue and balance are associated with cerebellar and brainstem involvement. This study provides early evidence supporting the theory that for those persons with MS who struggle to maintain steady balance during tasks that stimulate the central sensory integration process, complaints of significant levels of fatigue are probable.