The 50 most-cited articles in Medicine & Science in Sports & Exercise, 2020

PURPOSE: This study aimed to analyze the effect of resistance training (RT) performed until volitional failure with low, moderate, and high loads on muscle hypertrophy and muscle strength in healthy adults and to assess the possible participant-, design-, and training-related covariates that may affect the adaptations. METHODS: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science databases were searched. Including only studies that performed sets to volitional failure, the effects of low- (>15 repetitions maximum (RM)), moderate- (9-15 RM), and high-load (≤8 RM) RTs were examined in healthy adults. Network meta-analysis was undertaken to calculate the standardized mean difference (SMD) between RT loads in overall and subgroup analyses involving studies deemed of high quality. Associations between participant-, design-, and training-related covariates with SMD were assessed by univariate and multivariate network meta-regression analyses. RESULTS: Twenty-eight studies involving 747 healthy adults…

PURPOSE: This study aimed to compare the effects of four resistance training (RT) programs with different velocity loss (VL) thresholds: 0% (VL0), 10% (VL10), 20% (VL20), and 40% (VL40) on sprint and jump performance, muscle strength, neuromuscular, muscle hypertrophy, and architectural adaptations. METHODS: Sixty-four young resistance-trained men were randomly assigned into four groups (VL0, VL10, VL20, and VL40) that differed in the VL allowed in each set. Subjects followed an RT program for 8 wk (two sessions per week) using the full-squat (SQ) exercise, with similar relative intensity (70%-85% 1-repetition maximum), number of sets (3), and interset recovery period (4 min). Before and after the RT program, the following tests were performed: 1) muscle hypertrophy and architecture of the vastus lateralis (VLA), 2) tensiomyography, 3) 20-m running sprint, 4) vertical jump, 5) maximal voluntary isometric contraction in SQ, 6) progressive loading test in SQ, and 7) fatigue test. RESULTS: No between-group differences existed for RT-induced gains in sprint, jump, and strength…

PURPOSE: To assess injury risk in elite-level youth football (soccer) players based on anthropometric, motor coordination and physical performance measures with a machine learning model. METHODS: A total of 734 players in the U10 to U15 age categories (mean age, 11.7 ± 1.7 yr) from seven Belgian youth academies were prospectively followed during one season. Football exposure and occurring injuries were monitored continuously by the academies' coaching and medical staff, respectively. Preseason anthropometric measurements (height, weight, and sitting height) were taken and test batteries to assess motor coordination and physical fitness (strength, flexibility, speed, agility, and endurance) were performed. Extreme gradient boosting algorithms (XGBoost) were used to predict injury based on the preseason test results. Subsequently, the same approach was used to classify injuries as either overuse or acute. RESULTS: During the season, half of the players (n = 368) sustained at least one injury. Of the first occurring injuries, 173 were identified as overuse and 195 as acute injuries.…

PURPOSE: This study aimed to examine the effects of treadmill training on anxious-depressive-like behaviors of transgenic Alzheimer rats in the early stage of Alzheimer's disease (AD) and provided evidence of exercise in alleviating fear-avoidance behavior deficits. METHODS: Male 2-month-old TgF344-AD and wild-type rats were divided into wild-type (n = 9), AD (n = 8), and AD + treadmill exercise (Exe) groups (n = 12). After 8 months of exercise, the passive avoidance test, Barnes maze task, novel object recognition test, and object location test were used to measure learning and memory function. The open-field test, elevated plus maze, sucrose preference test, and forced swim test were conducted to determine the anxious-depressive-like behavior of AD rats. Immunofluorescence staining, Western blot analysis, enzyme-linked immunosorbent assay analysis, and related assay kits were used to measure inflammatory cytokines, oxidative stress, amyloid-β production, and tau hyperphosphorylation. RESULTS: Behavioral tests revealed that 12-month-old animals did not show any spatial learning and…

Nitric oxide (NO) is a gaseous signaling molecule that plays an important role in myriad physiological processes, including the regulation of vascular tone, neurotransmission, mitochondrial respiration, and skeletal muscle contractile function. NO may be produced via the canonical NO synthase-catalyzed oxidation of l-arginine and also by the sequential reduction of nitrate to nitrite and then NO. The body's nitrate stores can be augmented by the ingestion of nitrate-rich foods (primarily green leafy vegetables). NO bioavailability is greatly enhanced by the activity of bacteria residing in the mouth, which reduce nitrate to nitrite, thereby increasing the concentration of circulating nitrite, which can be reduced further to NO in regions of low oxygen availability. Recent investigations have focused on promoting this nitrate-nitrite-NO pathway to positively affect indices of cardiovascular health and exercise tolerance. It has been reported that dietary nitrate supplementation with beetroot juice lowers blood pressure in hypertensive patients, and sodium nitrite supplementation…

Although over 100 studies and reviews have examined the ergogenic effects of dietary nitrate (NO3) supplementation in young, healthy men and women, it is unclear if participant and environmental factors modulate the well-described ergogenic effects-particularly relevant factors include biological sex, aerobic fitness, and fraction of inspired oxygen (FiO2) during exercise. To address this limitation, the literature was systematically reviewed for randomized, crossover, placebo-controlled studies reporting exercise performance outcome metrics with NO3 supplementation in young, healthy adults. Of the 2033 articles identified, 80 were eligible for inclusion in the meta-analysis. Random-effects meta-analysis demonstrated that exercise performance improved with NO3 supplementation compared with placebo (d = 0.174; 95% confidence interval (CI), 0.120-0.229; P < 0.001). Subgroup analyses conducted on biological sex, aerobic fitness, and FiO2 demonstrated that the ergogenic effect of NO3 supplementation was as follows: 1) not observed in studies with only women (n = 6; d = 0.116; 95% CI,…

PURPOSE: In this study, we tested the effectiveness of a multicomponent sports-based program aimed at promoting early intervention, help seeking, and resilience among a sample of adolescent male sport participants. METHODS: The Ahead of the Game program comprised four intervention components and a messaging campaign. Two components targeted mental health literacy, intentions to seek and provide help, and resilience among adolescent boys. A mental health literacy program for parents and a coach education program to assist in the support of athletes' psychological needs were also included. We evaluated the program using a nonrandomized controlled trial matching two regional communities. In total, 350 sport participants (mean, 14.53 yr) were included in an intervention group, whereas 466 (mean, 14.66 yr) received usual practice in a matched control community. One hundred and eighty parents or caregivers and eight coaches also participated in the intervention components. Between-group mean differences on the primary and secondary outcomes were analyzed using linear mixed models,…

PURPOSE: High-intensity interval training (HIIT) has emerged as a time-efficient strategy to improve children's and adolescents' health-related fitness in comparison to traditional training methods. However, little is known regarding the effects on cognitive function and mental health. Therefore, the aim of this systematic review was to evaluate the effect of HIIT on cognitive function (basic information processing, executive function) and mental health (well-being, ill-being) outcomes for children and adolescents. METHODS: A systematic search was conducted, and studies were eligible if they 1) included a HIIT protocol, 2) examined cognitive function or mental health outcomes, and 3) examined children or adolescents (5-18 yr). Separate meta-analyses were conducted for acute and chronic studies, with potential moderators (i.e., study duration, risk of bias, participant age, cognitive demand, and study population) also explored. RESULTS: A total of 22 studies were included in the review. In acute studies, small to moderate effects were found for executive function (standardized mean…

INTRODUCTION: Chronic ankle instability (CAI) is known to induce impairments throughout the lower quarter kinetic chain, however there is currently no synthesized information on proximal adaptations of the trunk, hip, thigh, and knee for neuromuscular and biomechanical outcomes during strength, balance, jumping, and gait among CAI patients. The purpose of this systematic review and meta-analysis was to synthesize trunk, hip, thigh and knee neuromuscular and biomechanical outcome measures during functional assessments when comparing CAI to healthy groups. METHODS: Cumulative Index of Nursing and Allied Health Literature and Medical Literature Analysis and Retrieval System Online with PubMed databases were searched on June 3, 2019. Studies comparing outcomes at the trunk, hip, thigh, or knee regardless of assessment type in CAI versus healthy groups were considered for inclusion. Assessment categories were used to differentiate adaptations by assessment type after inclusion. Two independent reviewers assessed methodological quality using the Physiotherapy Evidence Database scoring…

PURPOSE: This study aimed to investigate the differences in muscle volumes and strength between male elite sprinters, sub-elite sprinters, and untrained controls and to assess the relationships of muscle volumes and strength with sprint performance. METHODS: Five elite sprinters (100-m season's best equivalent [SBE100], 10.10 ± 0.07 s), 26 sub-elite sprinters (SBE100, 10.80 ± 0.30 s), and 11 untrained control participants underwent 1) 3-T magnetic resonance imaging scans to determine the volume of 23 individual lower limb muscles/compartments and 5 functional muscle groups and 2) isometric strength assessment of lower body muscle groups. RESULTS: Total lower body muscularity was distinct between the groups (controls < sub-elite +20% < elite +48%). The hip extensors exhibited the largest muscle group differences/relationships (elite, +32% absolute and +15% relative [per kg] volume, vs sub-elite explaining 31%-48% of the variability in SBE100), whereas the plantarflexors showed no differences between sprint groups. Individual muscle differences showed pronounced anatomical specificity…

PURPOSE: The randomized controlled OptiTrain trial showed beneficial effects on fatigue after a 16-wk exercise intervention in patients with breast cancer undergoing adjuvant chemotherapy. We hypothesize that exercise alters systemic inflammation and that this partially mediates the beneficial effects of exercise on fatigue. METHODS: Two hundred and forty women scheduled for chemotherapy were randomized to 16 wk of resistance and high-intensity interval training (RT-HIIT), moderate-intensity aerobic and high-intensity interval training (AT-HIIT), or usual care (UC). In the current mechanistic analyses, we included all participants with >60% attendance and a random selection of controls (RT-HIIT = 30, AT-HIIT = 27, UC = 29). Fatigue (Piper Fatigue Scale) and 92 markers (e.g., interleukin-6 [IL-6] and tumor necrosis factor α [TNF-α]) were assessed at baseline and postintervention. Mediation analyses were conducted to explore whether changes in inflammation markers mediated the effect of exercise on fatigue. RESULTS: Overall, chemotherapy led to an increase in inflammation. The…

PURPOSE: The purpose of this study was to investigate differences in the associations between passive ankle dorsiflexion range of motion (ROM) and stiffness of the triceps surae, sciatic nerve, and deep fascia located in the posterior leg between young and older people. METHODS: Twenty young and twenty older males were recruited and were placed in a prone position with their hip and knee fully extended. Passive ankle dorsiflexion ROM was determined based on the onset of pain during passive dorsiflexion at 1°·s using an isokinetic dynamometer. Shear wave speeds (as a stiffness index) of the triceps surae, the sciatic nerve, and the deep fascia in the posterior leg were evaluated by ultrasound shear wave elastography. RESULTS: The shear wave speeds of the medial and lateral gastrocnemius measured at 15° dorsiflexion correlated negatively with passive ROM in young but not in older participants. The shear wave speed of the sciatic nerve measured at 15° dorsiflexion correlated negatively with passive ROM only in older participants. No association was observed between passive ROM and…

PURPOSE: We aimed to investigate differences between high-intensity interval exercise (HIIE, including high-intensity interval training and sprint interval training) and moderate-intensity continuous training (MICT) on physical fitness, body composition, blood pressure, blood lipids, insulin and glucose metabolism, inflammation, and endothelial function. METHODS: Differences between HIIE and MICT were summarized using a random-effects meta-analysis on the effect size (Cohen's d). A meta-regression was conducted using the following subgroups: population, age, training duration, men ratio, exercise type, baseline values (clinical relevant ranges), and type of HIIE. Studies were included if at least one of the following outcomes were reported: maximal oxygen uptake (V˙O2max), flow-mediated dilation (FMD), body mass index (BMI), body mass, percent body fat, systolic and diastolic blood pressure, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, total cholesterol, C-reactive protein (CRP), fasting glucose and insulin, glycated hemoglobin (HbA1c), and insulin…

The oxygen uptake (V[Combining Dot Above]O2) at the respiratory compensation point (RCP) closely identifies with the maximal metabolic steady state. However, the power output (PO) at RCP cannot be determined from contemporary ramp-incremental exercise protocols. PURPOSE: This study aimed to test the efficacy of a "step-ramp-step" (SRS) cycling protocol for estimating the PO at RCP and the validity of RCP as a maximal metabolic steady-state surrogate. METHODS: Ten heathy volunteers (5 women; age: 30 ± 7 yr; V[Combining Dot Above]O2max: 54 ± 6 mL·kg·min) performed in the following series: a moderate step transition to 100 W (MOD), ramp (30 W·min), and after 30 min of recovery, step transition to ~50% POpeak (HVY). Ventilatory and gas exchange data from the ramp were used to identify the V[Combining Dot Above]O2 at lactate threshold (LT) and RCP. The PO at LT was determined by the linear regression of the V[Combining Dot Above]O2 versus PO relationship after adjusting ramp data by the difference between the ramp PO at the steady-state V[Combining Dot Above]O2 from MOD and 100 W. Linear…

There is no doubt that many hypoxic conditions or prolonged exposures to altitude result in “biological costs of hypoxic adaptations that outweigh their benefits” (1), particularly in endurance athletes exposed to (a) exercise-induced arterial hypoxemia leading to a larger decrease in V˙O2max and aerobic endurance, (b) increased sympathetic activity and decreased baroreflex sensitivity, and (c) increased pulmonary arterial pressure. There is also no doubt that sleeping in moderate altitude (2000–3000 m) as performed by the athletes using either live high-train high (LHTH) or live high-train low (LHTL) methods leads to periodic breathing, intermittent hypoxia (IH), and increase in desaturation periods; for example, 3% oxygen desaturation index, but to a larger extent in hypobaric hypoxia (HH) (real altitude) than in normobaric hypoxia (NH) (simulated altitude), as shown at 2250 m (2). The three main questions debated in the present contrasting perspective are, however, different: Are there any evidences showing if the “counteracting maladaptation” (reported above) outweigh the…

PURPOSE: This study aimed to evaluate the effects of low energy availability (EA) on health and performance indices associated with the Male Athlete Triad and Relative Energy Deficiency in Sport (RED-S) models. METHODS: Over an 8-wk period, a male combat sport athlete adhered to a phased body mass (BM) loss plan consisting of 7-wk energy intake (EI) equating to resting metabolic rate (RMR) (1700 kcal·d-1) (phase 1), 5 d of reduced EI (1200-300 kcal·d-1) before weigh-in (phase 2), and 1 wk of ad libitum EI postcompetition (phase 3). EA fluctuated day by day because of variations in exercise energy expenditure. Regular assessments of body composition, RMR, cardiac function, cardiorespiratory capacity, strength and power, psychological state and blood clinical chemistry for endocrine, bone turnover, hydration, electrolyte, renal, liver, and lipid profiles were performed. RESULTS: BM was reduced over the 8-wk period by 13.5% (72.5 to 62.7 kg). No consequences of Male Athlete Triad or RED-S were evident during phase 1, where mean daily EA equated to 20 kcal·kg·fat free mass (FFM)-1·d-1…

PURPOSE: Resistance exercise improves an array of treatment-related adverse effects in men with prostate cancer; however, the minimal dosage required is unknown. We systematically reviewed the resistance training effects in prostate cancer patients to determine the minimal dosage regarding the exercise components (type, duration, volume, and intensity) on body composition, physical function, muscle strength, cardiorespiratory fitness, body mass index, and prostate-specific antigen. METHODS: Using PRISMA guidelines, MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science databases were searched. Eligible randomized controlled trials examined prostate cancer patients undertaking resistance-based exercise programs during or after treatment. Meta-analysis was undertaken when more than three studies were included. Associations between mean differences and exercise components were tested by univariate and multivariate meta-regression analysis. RESULTS: Twenty-three articles describing 21 trials and involving 1748 prostate cancer patients were included. Exercise improved fat mass (-1% in…

INTRODUCTION: Exogenous ketones potentially provide an alternative, energetically advantageous fuel to power exercising skeletal muscle. However, there is limited evidence regarding their relative contribution to energy expenditure during exercise. Furthermore, the effect of blood ketone concentration and exercise intensity on exogenous ketone oxidation rates is unknown. METHODS: Six athletes completed cycling ergometer exercise on three occasions within a single-blind, random-order controlled, crossover design study. Exercise duration was 60 min, consisting of 20-min intervals at 25%, 50%, and 75% maximal power output (WMax). Participants consumed (i) bitter flavored water (control), (ii) a low-dose β-hydroxybutyrate (βHB) ketone monoester (KME; 252 mg·kg BW-1, "low ketosis"), or (iii) a high-dose βHB KME (752 mg·kg BW-1, "high ketosis"). The KME contained a 13C isotope label, allowing for the determination of whole-body exogenous βHB oxidation rates through sampled respiratory gases. RESULTS: Despite an approximate doubling of blood βHB concentrations between low- and high-ketosis…

PURPOSE: The purposes of our study were to evaluate Achilles tendon loading profiles of various exercises and to develop guidelines to incrementally increase the rate and magnitude of Achilles tendon loading during rehabilitation. METHODS: Eight healthy young adults completed a battery of rehabilitation exercises. During each exercise, we collected three-dimensional motion capture and ground reaction force data to estimate Achilles tendon loading biomechanics. Using these loading estimates, we developed an exercise progression that incrementally increases Achilles tendon loading based on the magnitude, duration, and rate of tendon loading. RESULTS: We found that Achilles tendon loading could be incrementally increased using a set of either isolated ankle movements or multijoint movements. Peak Achilles tendon loads varied more than 12-fold, from 0.5 bodyweights during a seated heel raise to 7.3 bodyweights during a forward single-leg hop. Asymmetric stepping movements like lunges, step ups, and step downs provide additional flexibility for prescribing tendon loading on a…

PURPOSE: Prolonged sitting is associated with cardiometabolic complications. The study purpose was to investigate whether breaking up prolonged sitting with brief stair climbing exercise "snacks" could lower postprandial insulin, glucose, and free fatty acids responses. METHODS: In two separate randomized crossover studies, 12 young healthy-weight men (study 1) and 11 adults with overweight/obesity (OW; study 2) completed two experimental conditions: i) sedentary (SED; 9-h sitting) and ii) stair climbing snacks (SS; 8 × 15-30 s once per hour). The same high-glycemic index meals were consumed at 0, 3, and 6 h at each condition. The primary outcome was total insulin area under the curve (AUC) across 9 h. RESULTS: In healthy-weight men, there were no significant differences between SS and SED for total (9-h) insulin AUC (P = 0.24, d = 0.4), total glucose AUC (P = 0.17, d = 0.48), total nonesterified fatty acid (NEFA) AUC (P = 0.22, d = 0.4), or total triglyceride AUC (P = 0.72). In adults with OW, total insulin AUC (-16.5%, P = 0.036, d = 0.94) and total NEFA AUC (-21%, P = 0.016, d =…

PURPOSE: This study aimed to identify clinical predictors of postconcussion subsequent musculoskeletal (MSK) injuries. METHODS: We recruited 66 National Collegiate Athletic Association intercollegiate student-athletes with a diagnosed concussion as well as 36 National Collegiate Athletic Association student-athletes without a concussion. All participants completed a multifaceted concussion baseline consisting of 1) 22-item 0-6 self-reported symptom checklist with outcomes including both the number of symptoms endorsed (0-22) and 2) total symptom score (0-132), 3) Standard Assessment of Concussion, 4) Balance Error Scoring System, 5) Immediate Post-Concussion Assessment and Cognitive Testing, 6) clinical reaction time, and 7) the King-Devick as well as demographic and injury characteristics. The concussion participants completed the same examination acutely postconcussion, and binary logistic regression was used to identify predictors of subsequent MSK from the change scores (acute minus baseline). From the 66 concussed student-athletes, a subset 36, matched with the healthy…

PURPOSE: We investigated the effects of seated versus prone leg curl training on hamstrings muscle hypertrophy and susceptibility to eccentric exercise-induced muscle damage. METHODS: Part 1: Twenty healthy adults conducted seated leg curl training with one leg (Seated-Leg) and prone with the other (Prone-Leg), at 70% one-repetition maximum (1RM), 10 repetitions per set, 5 sets per session, 2 sessions per week for 12 wk. Magnetic resonance imaging (MRI)-measured muscle volume of the individual and whole hamstrings was assessed pre- and posttraining. Part 2: Nineteen participants from part 1 and another 12 untrained controls (Control-Leg) performed eccentric phase-only leg curl exercise at 90% 1RM, 10 repetitions per set, 3 sets for each of the seated/prone conditions with each leg. MRI-measured transverse relaxation time (T2) and 1RM of seated/prone leg curl were assessed before, 24, 48, and 72 h after exercise. RESULTS: Part 1: Training-induced increases in muscle volume were greater in Seated-Leg versus Prone-Leg for the whole hamstrings (+14% vs +9%) and each biarticular (+8%-24%…

PURPOSE: To determine age-dependent cutoff values for secondary exhaustion criteria for a general population free of exercise limiting chronic conditions; to describe the percentage of participants reaching commonly used exhaustion criteria during a cardiopulmonary exercise test (CPET); and to analyze their oxygen uptake at the respective criteria to quantify the impact of a given criterion on the respective oxygen uptake (V˙O2) values. METHODS: Data from the COmPLETE-Health Study were analyzed involving participants from 20 to 91 yr of age. All underwent a CPET to maximal voluntary exertion using a cycle ergometer. To determine new exhaustion criteria, based on maximal respiratory exchange ratio (RERmax) and age-predicted maximal HR (APMHR), one-sided lower tolerance intervals for the tests confirming V˙O2 plateau status were calculated using a confidence level of 95% and a coverage of 90%. RESULTS: A total of 274 men and 252 women participated in the study. Participants were nearly equally distributed across age decades from 20 to >80 yr. A V˙O2 plateau was present in 32%. There…

PURPOSE: Greater leisure-time physical activity (LTPA) associates with healthier lives, but knowledge regarding occupational physical activity (OPA) is more inconsistent. DNA methylation (DNAm) patterns capture age-related changes in different tissues. We aimed to assess how LTPA and OPA are associated with three DNAm-based epigenetic age estimates, namely, DNAm age, PhenoAge, and GrimAge. METHODS: The participants were young adult (21-25 yr, n = 285) and older (55-74 yr, n = 235) twin pairs, including 16 pairs with documented long-term LTPA discordance. Genome-wide DNAm from blood samples was used to compute DNAm age, PhenoAge, and GrimAge Age acceleration (Acc), which describes the difference between chronological and epigenetic ages. Physical activity was assessed with sport, leisure-time, and work indices based on the Baecke Questionnaire. Genetic and environmental variance components of epigenetic age Acc were estimated by quantitative genetic modeling. RESULTS: Epigenetic age Acc was highly heritable in young adult and older twin pairs (~60%). Sport index was associated with…

PURPOSE: Eight weeks of time-restricted eating (TRE) in concert with habitual exercise training was investigated for effects on body composition, energy and macronutrient intakes, indices of endurance running performance, and markers of metabolic health in endurance athletes. METHODS: Male middle- and long-distance runners (n = 23) were randomly assigned to TRE (n = 12) or habitual dietary intake (CON; n = 11). TRE required participants to consume all of their dietary intake within an 8-h eating window (so-called 16:8 TRE), but dietary patterns, food choices, and energy intake were ad libitum during this window. Participants continued their habitual training during the intervention period. Participants completed an incremental exercise test before (PRE) and after (POST) the 8-wk intervention for the assessment of blood lactate concentrations, running economy, and maximal oxygen uptake. Fasted blood samples were analyzed for glucose, insulin, and triglyceride concentrations. Dietary intake was assessed at PRE, MID (week 4), and POST using a 4-d semiweighed food diary. RESULTS:…

PURPOSE: We recently reported that oral ketone ester (KE) intake before and during the initial 30 min of a 3 h 15 min simulated cycling race (RACE) transiently decreased blood pH and bicarbonate without affecting maximal performance in the final quarter of the event. We hypothesized that acid-base disturbances due to KE overrules the ergogenic potential of exogenous ketosis in endurance exercise. METHODS: Nine well-trained male cyclists participated in a similar RACE consisting of 3 h submaximal intermittent cycling (IMT180') followed by a 15-min time trial (TT15') preceding an all-out sprint at 175% of lactate threshold (SPRINT). In a randomized crossover design, participants received (i) 65 g KE, (ii) 300 mg·kg-1 body weight NaHCO3 (BIC), (iii) KE + BIC, or (iv) a control drink (CON), together with consistent 60 g·h-1 carbohydrate intake. RESULTS: KE ingestion transiently elevated blood D-ß-hydroxybutyrate to ~2-3 mM during the initial 2 h of RACE (P < 0.001 vs CON). In KE, blood pH concomitantly dropped from 7.43 to 7.36 whereas bicarbonate decreased from 25.5 to 20.5 mM (both P…

INTRODUCTION: Approximately 25% of people with sport-related concussion (SRC) experiences persistent symptoms. The 2016 Berlin consensus on SRC recommends symptom-limited aerobic exercise as a rehabilitation option for persistent symptoms after concussion. However, this recommendation is based on a limited body of knowledge because there is uncertainty about the effectiveness of such interventions. The objective of this systematic review is to assess the effects of symptom-limited aerobic exercise programs compared with control interventions on symptom intensity in individuals with SRC. METHODS: A structured search was conducted in MEDLINE, EMBASE, CINHAL, and EBM reviews. Randomized clinical trials (RCT) including aerobic exercise programs as an intervention for SRC were included. After selection, the risk of bias and Grading of Recommendations, Assessment, Development and Evaluation recommendations were applied to pooled studies for quantitative analysis. Standard mean differences (SMD) and 95% confidence interval (CI) were calculated. A descriptive analysis was also performed.…

PURPOSE: The purpose of this systematic review was to evaluate fetal and maternal pregnancy outcomes of elite athletes who had participated in competitive sport immediately before conception. METHODS: Online databases were searched up to March 24, 2020. Studies of any design and language were eligible if they contained information on the relevant population (pregnant women), exposure (engaged in elite sport immediately before pregnancy), and outcomes (birth weight, low birth weight, macrosomia, preterm birth, fetal heart rate and pulse index, cesarean sections, instrumental deliveries, episiotomies, duration of labor, perineal tears, pregnancy-induced low back pain, pelvic girdle pain, urinary incontinence, miscarriages, prenatal weight gain, inadequate/excess prenatal weight gain, maternal depression or anxiety). RESULTS: Eleven unique studies (n = 2256 women) were included. We identified "low" certainty evidence demonstrating lower rates of low back pain in elite athletes compared with active/sedentary controls (n = 248; odds ratio, 0.38; 95% confidence interval, 0.20-0.73; I2 =…

PURPOSE: The purpose was to examine gait characteristics between collegiate athletes who did and did not sustain a lower-extremity musculoskeletal (LEMSK) injury in the year after concussion. METHODS: Thirty-four NCAA collegiate athletes with diagnosed concussions were divided into two groups based on if they did (n = 16) or did not (n = 18) sustain a LEMSK in the year after concussion. Participants completed baseline testing before the start of the season and again at return to play postconcussion. Injuries were tracked using an electronic medical database. Participants were instrumented with three APDM Opal triaxial accelerometers and performed five single-task (ST) and five dual-task (DT) gait trials. Participants traversed a 10-meter walkway, turned around a specified endpoint, and returned to the original line. During DT, participants simultaneously walked and answered mini-mental style questions. A linear mixed-effects model assessed interactions and/or main effects between groups for gait speed, double support time, cadence, stride length, and cognitive accuracy. RESULTS: The…

PURPOSE: Recent research suggests that stroboscopic training is an effective tool to improve visual and visuomotor performance. However, many studies were limited by small samples, short training interventions, inexperienced athletes, and an exclusive focus on short-term effects. This first part of the study evaluates the short- and long-term effects of stroboscopic training on visuomotor reaction speed in elite athletes. METHODS: Forty-five young elite badminton athletes participated in this study, of which 32 (13.7 yr) were included in the final data analysis. Participants were assigned to an intervention (stroboscopic vision) or control group (normal vision). Both groups performed identical badminton-specific training drills implemented into the regular training schedule. Before and after a 10-wk training period and after a 6-wk retention interval, athletes performed a laboratory reaction test to determine EMG onset and visuomotor reaction time (VMRT). In addition, a field test investigated stroboscopic training effects on the quality of ball-racquet contact and net drop…

INTRODUCTION: Sleep, sedentary behavior, and physical activity are each independently associated with cardiovascular health (CVH). It is unknown how substituting time in sedentary behavior with sleep or physical activity affects overall CVH. METHODS: Data for this analysis were taken from the Multi-Ethnic Study on Atherosclerosis Sleep Ancillary Study. Eligible participants (N = 1718) wore Actiwatch accelerometers for 24 h and had at least 3 d of valid accelerometry. The American Heart Association's Life's Simple 7 was used to represent the CVH score after excluding the physical activity component, with higher scores indicating more favorable CVH. Isotemporal substitution modeling was conducted to examine the effect of substituting 30 min of sedentary time for an equivalent amount of sleep, light-intensity physical activity (LIPA), or moderate to vigorous physical activity (MVPA). RESULTS: Substituting 30 min of sedentary time to sleep, LIPA, and MVPA was associated with a significantly higher CVH score [β (95% confidence interval) = 0.077 (0.056), 0.039 (0.033), and 0.485 (0.127),…

INTRODUCTION: Increasing age is associated with decrements in sweat rate that compromise whole-body total heat loss (evaporative + dry heat exchange) in both men and women during moderate-to-vigorous exercise in dry heat. Similarly, young women also display reductions in sweating (that lower evaporative heat loss) relative to young men in such conditions. Nevertheless, it remained unclear whether these effects act synergistically to exacerbate the age-related decline in whole-body total heat loss in women relative to men. We therefore assessed the interrelation between age and sex on whole-body total heat loss during light, moderate, and vigorous exercise in dry heat. METHODS: To achieve this, we used direct and indirect calorimetry to assess whole-body total heat loss and metabolic heat production (respectively) in 46 men and 34 women age between 18 and 70 yr. Participants performed three, 30-min bouts of cycling at metabolic heat productions of 150 (light), 200 (moderate), and 250 (vigorous) W·m, each separated by 15-min recovery in dry heat (40°C, ~15% relative humidity).…

OBJECTIVES: To examine if the associations between motor competence and physical activity and musculoskeletal fitness change over time, whether motor competence is associated with longitudinal trajectories of physical activity and fitness, and mediating pathways among these constructs across early childhood. METHODS: Four hundred and eighteen children 3 to 5 yr of age (210 boys; age, 4.5 ± 1.0 yr) were recruited and completed three annual assessments as part of the Health Outcomes and Physical activity in Preschoolers study. Motor competence was assessed using the Bruininks-Oseretsky Test of Motor Proficiency Second Edition-Short Form. Musculoskeletal fitness (short-term muscle power) was evaluated using a modified 10-s Wingate protocol on a cycle ergometer. Physical activity was measured over 7 d using accelerometers. RESULTS: At baseline, the cross-sectional relationship between motor competence and vigorous physical activity was not significant; however, a significant, weak positive association emerged across time. Results from longitudinal mixed-effect models found motor…

PURPOSE: The present study investigated muscle metabolism and fatigue during simulated elite male ice hockey match-play. METHODS: Thirty U20 male national team players completed an experimental game comprising three periods of 8 × 1-min shifts separated by 2-min recovery intervals. Two vastus lateralis biopsies were obtained either during the game (n = 7) or pregame and postgame (n = 6). Venous blood samples were drawn pregame and at the end of the first and last periods (n = 14). Activity pattern and physiological responses were continuously monitored using local positioning system and heart rate recordings. Further, repeated-sprint ability was tested pregame and after each period. RESULTS: Total distance covered was 5980 ± 199 m with almost half the distance covered at high skating speeds (>17 km·h). Average and peak on-ice heart rate was 84% ± 2% and 97% ± 2% of maximum heart rate, respectively. Muscle lactate increased (P ≤ 0.05) more than fivefold and threefold, whereas muscle pH decreased (P ≤ 0.05) from 7.31 ± 0.04 pregame to 6.99 ± 0.07 and 7.13 ± 0.11 during the first and…

INTRODUCTION: Critical speed (CS) represents the highest intensity at which a physiological steady state may be reached. The aim of this study was to evaluate whether estimations of CS obtained from raw training data can predict performance and pacing in marathons. METHODS: We investigated running activities logged into an online fitness platform by >25,000 recreational athletes before big-city marathons. Each activity contained time, distance, and elevation every 100 m. We computed grade-adjusted pacing and the fastest pace recorded for a set of target distances (400, 800, 1000, 1500, 3000, and 5000 m). CS was determined as the slope of the distance-time relationship using all combinations of, at least, three target distances. RESULTS: The relationship between distance and time was linear, irrespective of the target distances used (pooled mean ± SD: R = 0.9999 ± 0.0001). The estimated values of CS from all models were not different (3.74 ± 0.08 m·s), and all models correlated with marathon performance (R = 0.672 ± 0.036, error = 8.01% ± 0.51%). CS from the model including 400, 800,…

PURPOSE: Sedentary behavior increases the risk for cardiovascular and cerebrovascular disease. To understand potential benefits and underlying mechanisms, we examined the acute and long-term effect of reduced sitting intervention on vascular and cerebrovascular function. METHODS: This prospective study included 24 individuals with increased cardiovascular risk (65 ± 5 yr, 29.8 ± 3.9 kg·m-2). Before and after 16-wk reduced sitting, using a mobile health device with vibrotactile feedback, we examined (i) vascular function (flow-mediated dilation [FMD]), (ii) cerebral blood flow velocity (CBFv, transcranial Doppler), and (iii) cerebrovascular function (cerebral autoregulation [CA] and cerebral vasomotor reactivity [CVMR]). To better understand potential underlying mechanisms, before and after intervention, we evaluated the effects of 3 h sitting with and without light-intensity physical activity breaks (every 30 min). RESULTS: The first wave of participants showed no change in sedentary time (n = 9, 10.3 ± 0.5 to 10.2 ± 0.5 h·d-1, P = 0.87). Upon intervention optimization by…

PURPOSE: This study aimed to examine how compositions of 24-h time use and time reallocations between movement behaviors are associated with cardiometabolic health in a population-based sample of middle-age Finnish adults. METHODS: Participants were 3443 adults 46 yr of age from the Northern Finland Birth Cohort 1966 study. Participants wore a hip-worn accelerometer for 14 d from which time spent in sedentary behavior (SB), light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) were determined. These data were combined with self-reported sleep to obtain the 24-h time-use composition. Cardiometabolic outcomes included adiposity markers, blood lipid levels, and markers of glucose control and insulin sensitivity. Multivariable-adjusted regression analysis, using a compositional data analysis approach based on isometric log-ratio transformation, was used to examine associations between movement behaviors with cardiometabolic outcomes. RESULTS: More daily time in MVPA and LPA, relative to other movement behaviors, was consistently favorably…

PURPOSE: Some evidence suggests that sedentary women may be more vulnerable to cognitive task-induced mental fatigue. Mental fatigue, in turn, may worse aerobic exercise performance, presumably via increased perceived effort. However, it remains unclear whether acute mental fatigue induction increases perceived effort and worsens endurance performance in high-level professional athletes and whether such effects are influenced by sex. METHODS: We studied 30 athletes (15 women and 16 men) in a single-blinded, randomized, controlled and crossover protocol. In separate visits, athletes either performed a 45-min cognitive task (Stroop's color-word conflict test) to induce mental fatigue or watched a 45-min documentary as control. Then athletes performed a time-to-exhaustion test on a treadmill. RESULTS: Perceptual measures and cognitive performance indicated that the prolonged cognitive task induced a similar mental fatigue state in women and men. Cardiorespiratory and metabolic responses to the TEE did not change with mental fatigue in both sexes. Mental fatigue increased perceived…

PURPOSE: Exercise increases pressure pain thresholds (PPT) in pain-free individuals, known as exercise-induced hypoalgesia (EIH). Positive preexercise information can elicit higher EIH responses, but the effect of positive versus negative preexercise information on EIH is unknown. The primary aim of this randomized controlled trial was to compare EIH at the exercising thigh muscle after an isometric squat exercise between individuals receiving positive versus negative preexercise information about the effect of exercise on pain. Secondary aims were to compare EIH at nonexercising muscles between groups, and to investigate the relationship between participants' expectations and EIH. METHODS: Eighty-three participants were randomly assigned to brief positive (n = 28), neutral (n = 28) or negative (n = 27) verbal information. The neutral information group was included in the study as a reference group. Pressure pain thresholds at the thigh and trapezius muscles were assessed before and after the intervention (i.e., preexercise information+squat exercise). Expectations of pain relief…

INTRODUCTION: Distinct physiological responses to exercise occur in the heavy- and severe-intensity domains, which are separated by the critical power or critical torque (CT). However, how the transition between these intensity domains actually occurs is not known. We tested the hypothesis that CT is a sudden threshold, with no gradual transition from heavy- to severe-intensity behavior within the confidence limits associated with the CT. METHODS: Twelve healthy participants performed four exhaustive severe-intensity trials for the determination of CT, and four 30-min trials in close proximity to CT (one or two SE above or below each participant's CT estimate; CT - 2, CT - 1, CT + 1, CT + 2). Muscle O2 uptake, rectified electromyogram, and torque variability and complexity were monitored throughout each trial, and maximal voluntary contractions (MVC) with femoral nerve stimulation were performed before and after each trial to determine central and peripheral fatigue responses. RESULTS: The rates of change in fatigue-related variables, muscle O2 uptake, electromyogram amplitude, and…

PURPOSE: This study aimed to investigate the effects of blood flow restriction (BFR) combined with electrical muscle stimulation (EMS) on skeletal muscle mass and strength during a period of limb disuse. METHODS: Thirty healthy participants (22 ± 3 yr; 23 ± 3 kg·m-2) were randomly assigned to control (CON; n = 10), BFR alone (BFR; n = 10), or BFR combined with EMS (BFR + EMS; n = 10). All participants completed unloading of a single leg for 14 d, with no treatment (CON), or while treated with either BFR or BFR + EMS (twice daily, 5 d·wk-1). BFR treatment involved arterial three cycles of 5-min occlusion using suprasystolic pressure, each separated by 5 min of reperfusion. EMS (6 s on, 15 s off; 200 μs; 60 Hz; 15% maximal voluntary contraction [MVC]) was applied continuously throughout the three BFR cycles. Quadriceps muscle mass (whole-thigh lean mass via dual-energy x-ray absorptiometry and vastus lateralis [VL] muscle thickness via ultrasound) and strength (via knee extension MVC) were assessed before and after the 14-d unloading period. RESULTS: After limb unloading, whole-thigh…

PURPOSE: This study aimed to verify the effect of 6 months of periodized resistance training (RT) with and without blood flow restriction (BFR) in patients with stage 2 chronic kidney disease (CKD) on glomerular filtration rate (GFR), uremic parameters, cytokines, and klotho-fibroblast growth factor 23 (FGF23) axis. METHODS: A total of 105 subjects were randomized in three groups of 35 each: control (CTL), RT, and RT + BFR. A first visit was required for an anamnesis to evaluate the number of medications and anthropometric measurements (body weight, height, and body mass index). Muscle strength (one-repetition maximum) was assessed. Venous blood samples were collected at baseline and after 6 months of training in all patients for the analysis of markers of renal function and integrity, as well as for the determination of the inflammatory profile. Statistical significances were adopted with P < 0.05. RESULTS: Both training therapies attenuated the decline of GFR (P < 0.05). The majority of CTL patients declined to stage 3 CKD (88.5%), whereas fewer incidents were noted with RT…

PURPOSE: Cardiopulmonary exercise testing (CPET) is an important measurement in clinical practice, and its primary outcome, maximal oxygen uptake (V˙O2peak), is inversely associated with morbidity and mortality. The purposes of this study are to provide CPET reference values for maximal and submaximal parameters across the adult age spectrum of a healthy European cohort, to compare V˙O2peak values with other reference data sets, and to analyze the associations between physical activity (PA) levels and CPET parameters. METHODS: In this cross-sectional study, we prospectively recruited 502 participants (47% female) from 20 to 90 yr old. The subjects performed a CPET on a cycle ergometer using a ramp protocol. PA was objectively and continuously measured over 14 d using a triaxial accelerometer. Quantile curves were calculated for CPET parameters. To investigate the associations between CPET parameters and PA levels, linear regression analysis was performed. RESULTS: V˙O2peak values observed in the group of 20-29 yr were 46.6 ± 7.9 and 39.3 ± 6.5 mL·kg⋅min for males and females,…

INTRODUCTION: This study aimed to model the dissociation in the V˙O2/power output (PO) relationship between ramp incremental (RI) and constant work rate (CWR) exercise and to develop a novel strategy that resolves this gap and enables an accurate translation of the RI V˙O2 response into a constant PO. METHODS: Nine young men completed two RI tests (30 and 15 W·min) and CWR tests at seven intensities across exercise intensity domains. The V˙O2/PO relationship for RI and CWR exercise was modeled, and the dissociation was compared in terms of PO. The accuracy of three translation strategies was tested in the moderate-intensity (i.e., zone 1) and heavy-intensity (i.e., zone 2) domain. Strategy 1 comprised a simple mean response time correction, whereas strategies 2 and 3 accounted for the loss of mechanical efficiency in zone 2 by applying an extra correction that was based on, respectively, the difference between s2 - CWR and s2 - ramp and the ratio s2/s1. RESULTS: For all intensities, differences in PO were found between CWR and RI exercise (P < 0.001). Overall, these differences were…

PURPOSE: This study aimed to test the hypothesis that aerobic exercise performance is impaired in the midluteal (ML) compared with the midfollicular (MF) phase of the menstrual cycle. METHODS: Twelve recreationally active eumenorrheic women (25 ± 6 yr) completed exercise sessions during the MF and the ML phases. Each session consisted of an 8-km cycling time trial that was preceded by 10 min of cycling performed at a constant power below and above gas exchange threshold. Heart rate, ventilation, and oxygen uptake were continuously measured. RPE and ratings of fatigue were assessed during the time trial using visual analog scales. Total mood disturbance was calculated from the POMS questionnaire administered before and 20 min postexercise. RESULTS: Salivary progesterone concentration was 578 ± 515 pg·mL-1 higher in ML compared with MF phase (P < 0.01), whereas estradiol concentration did not differ between phases (167 ± 55 vs 206 ± 120 pg·mL-1, P = 0.31). Total mood disturbance before exercise was greater during the ML phase compared with the MF phase (P < 0.01), but this difference…

PURPOSE: Although most pediatric cancer patients survive, those who undergo anticancer treatments like chemotherapy and/or radiotherapy are at a high risk for late effects, such as cognitive deficits. To counteract these deficits, feasible and effective interventions are needed. The aim of this study was to compare the effects of working memory training, exergaming, and a wait-list control condition on cognitive functions in pediatric cancer survivors. METHODS: In a parallel-group randomized trial, 69 pediatric cancer survivors aged 7-16 yr (mean = 11.35, SD = 3.53) were randomly assigned to 8-wk working memory training, exergaming, or a wait-list control group. Each training course consisted of three 45-min training sessions per week. The primary outcome comprised the core executive functions (visual working memory, inhibition, switching), and the secondary outcomes included other cognitive domains (intelligence, planning, memory, attention, processing speed), motor abilities, and parent rating on their children's executive functions. Assessments were conducted both before and…

PURPOSE: Video gamers exceeding screen-time limits are at greater risk of experiencing health issues associated with physical inactivity. Demonstrating that exercise has positive effects on video game performance could promote physical activity among video gamers. We investigated the short-term effects of a single session of cardiovascular exercise on the performance of the popular video game League of Legends (LoL) and explored psychosocial mechanisms. METHODS: Twenty young video gamers played a customized LoL task preceded by a short bout of high-intensity interval training or a period of rest. The two conditions were administered on two separate days in a randomized counterbalanced fashion. Video game performance was assessed as the total number of targets eliminated as well as accuracy, defined as the ability to eliminate targets using single attacks. Short-term changes in affect after exercise as well as exercise enjoyment were also assessed. RESULTS: Exercise improved (P = 0.027) the capacity to eliminate targets (mean ± SEM, 121.17 ± 3.78) compared with rest (111.38 ± 3.43).…

Prepubertal children (6-12 yr) differ from adults in various morphological and physiological factors that may influence thermoregulatory function; however, experimental evidence of meaningful child-adult differences in heat strain during exercise-heat stress is sparse, despite numerous studies. Although we appreciate the challenges associated with performing such comparisons, part of that discrepancy may be due to the methods used. Nonetheless, a focused discussion of these methodological considerations and their implications for current understanding remains unavailable. This is an important knowledge gap given the threat to health posed by rising global temperatures and the ongoing focus on improving physical activity levels in children. The aims of this methodological review were, therefore, to (i) review the theoretical basis for child-adult differences in thermoregulatory function, (ii) describe previous comparisons of exercise thermoregulation between prepubertal children and adults, (iii) discuss two methodological issues associated with that research, which, in our view,…

PURPOSE: Mental fatigue impairs psychomotor skill performance by affecting visuomotor reaction time, accuracy, and decision-making. Recently, neurocognitive functional performance tests (FPT) that integrate these outcomes have been developed. The aim of this study was to assess the effect of mental fatigue on traditional and neurocognitive FPT in healthy adults. METHODS: Fourteen volunteers (four women; mean ± SD age, 22 ± 1 yr; height, 176.9 ± 8.4 cm; weight, 69.7 ± 10.4 kg) participated in a randomized counterbalanced crossover design. A 100% incongruent Stroop color word test of 90 min was used to induce mental fatigue and the control task encompassed watching a 90-min documentary. Traditional FPT comprised a single-leg hop for distance, countermovement jump, and Y-balance test, whereas the neurocognitive FPT encompassed the reactive balance test (RBT). All FPTs were evaluated pre-post the 90-min task. Mental fatigue was assessed using the Stroop task, visual analog scale for mental fatigue, and the Eriksen-Flanker task. RESULTS: Mental fatigue was successfully induced, as shown…

PURPOSE: Confounding due to poor health is a concern in accelerometer-based studies of physical activity and health, but detailed investigations of this source of bias are lacking. METHODS: US adults (n = 4840) from the National Health and Nutrition Examination Survey (2003 to 2006) wore an accelerometer for 1 to 7 d (mean = 5.7 d) and were followed for mortality through 2015. Logistic regression was used to examine odds ratios between poor health (chronic conditions, self-reported health, mobility limitations, frailty) and low physical activity levels; Cox models were used to estimate adjusted hazard ratios (HR) and 95% CI for mortality associations for a 1 h·d increase in moderate-to-vigorous-intensity physical activity (MVPA) using two commonly used cut-points (MVPA760, MVPA2020). Modeling scenarios with shorter and longer follow-up time, increasing adjustment for poor health, by age group, and after excluding early years of follow-up were used to assess bias. RESULTS: Over a mean of 10.1 yr of follow-up, 1165 deaths occurred. Poor health was associated with low MVPA760 levels…