Medicine and Science in Sports and Exercise

INTRODUCTION: Aberrant gait variability has been observed following anterior cruciate ligament reconstruction (ACLR), yet it remains unknown if gait variability associates with early changes in cartilage composition linked to osteoarthritis development. Our purpose was to determine the association between femoral articular cartilage T1ρ magnetic resonance imaging (MRI) relaxation times and gait variability. METHODS: T1ρ MRI and gait kinematics were collected in 22 ACLR participants (13 Females; 21 ± 4 years old; 7...

PURPOSE: We investigated short-term (9 d) exposure to low energy availability (LEA) in elite endurance athletes during a block of intensified training on self-reported well-being, body composition and performance. METHODS: Twenty-three highly trained race walkers undertook a ~ 3 w research-embedded training camp during which they undertook baseline testing and 6 d of high energy/carbohydrate (CHO) availability (40 kcal·kg FFM-1·d-1) before being allocated to 9 d continuation of this diet (HCHO: n = 10 M, 2F) or a significant decrease in energy availability to 15 kcal·kg FFM-1·d-1 (LEA: n = 10 M, 1F)...

PURPOSE: This study aimed to explore the effect of exercise and cold exposure on insulin sensitivity and the level of serum free fatty acids (FFAs) in diet-induced obese rats. METHODS: 64 diet-induced obese rats were randomly assigned to eight groups: room temperature -sedentary, room temperature -exercise, acute cold exposure -sedentary, acute cold exposure -exercise, intermittent cold exposure -sedentary, intermittent cold exposure -exercise, sustained cold exposure -sedentary, and sustained cold exposure -exercise...

PURPOSE: The purpose of this study was to examine the suitability of a single ramp incremental test to predict critical power (CP) and W'. We hypothesized that CP would correspond to the corrected power output (PO) at the respiratory compensation point (RCP) and W' would be calculable from the work done above RCP. METHODS: 153 healthy young people (26 ± 4 yr, 51.4 ± 7.6 mL·min-1·kg-1) performed a maximal ramp test (20, 25 or 30 W·min-1), followed by three to five constant load trials to determine CP and W'...

BACKGROUND: Exercise is a proven therapy for managing cardiometabolic risk factors in type 2 diabetes (T2D). However, its effects on patient-reported outcome measures such as quality of life (QoL) in people with type 2 diabetes remain unclear. Consequently, the primary aim of this study was to determine the effect of regular exercise on QoL in adults with T2D. A secondary aim was to determine the effect of different exercise modalities on QoL. The third aim was to determine whether improvements in QoL were associated with improvements in glycated hemoglobin (A1C)...

PURPOSE: We investigated the effects of gut microbes, and the mechanisms mediating the enhanced exercise performance induced by exercise training, i.e., skeletal muscle blood flow, and mitochondrial biogenesis and oxidative function in male mice. METHODS: All mice received a graded exercise test prior to (PRE) and following exercise training via forced treadmill running at 60-70% of maximal running capacity 5 d/wk for 5 weeks (POST). To examine the role of the gut microbes, the graded exercise was repeated after 7 days of access to antibiotic treated water (ABX), used to eliminate gut microbes...

PURPOSE: This study assessed the effects of the COVID-19 pandemic restrictions/lockdowns on physical activity levels, body mass, quadriceps strength and gait biomechanics over 18 months. METHODS: Ten healthy men were assessed at baseline (~14 weeks before first lockdown) and 17.9 ± 0.3 months later (<1 week after second lockdown). At both times, physical activity levels, body mass and quadriceps strength were acquired using the International Physical Activity Questionnaire, a force plate, and a dynamometer, respectively...

PURPOSE: Previous research has focused on device-based measures of activity compensation, with little understanding of how children perceive potential compensatory responses to activity or inactivity, or whether these change following periods of activity or inactivity. The aim of this study was to (a) explore the alignment between children's self-reported usual compensation and compensation recall following experimental conditions; and (b) examine sex differences. METHODS: In total, 360 children (47% boys) participated in at least one of three experimental conditions over six weeks (a) restricted physical activity (PA; indoor play); (b) imposed moderate-to vigorous PA (MVPA; sports class); and (c) imposed light PA (LPA; standing lesson)...

PURPOSE: The purpose of this study was to examine the relationships between pitcher trunk and throwing arm girth with kinematics at ball release of the softball pitch. Softball pitchers can be of various shapes and sizes; however, it is unknown if segment girth might influence pitch biomechanics. Because of the importance of body positioning at ball release of the windmill pitch, this study examined the relationship between segment girth and pitch biomechanics at ball release. METHODS: Forty-two pitchers volunteered to participate (1...

INTRODUCTION: Interrupting sedentary time during the day reduces postprandial glycemia (a risk factor for cardio-metabolic disease). However, it is not known if benefits exist for postprandial glucose, insulin and triglyceride responses in the evening, and if these benefits differ by BMI category. METHODS: In a randomized crossover study, 30 participants (aged 25.4 ± 5.4 years; BMI 18.5-24.9: n = 10, BMI 25-29.9: n = 10, BMI ≥30: n = 10), completed two intervention arms, beginning at ~1700 h: prolonged sitting for 4 h; and sitting with regular activity breaks of 3 min of resistance exercises every 30 min...

PURPOSE: Few longitudinal studies have investigated the interwoven longitudinal dynamics between physical activity (PA), motor performance, and academic skills in middle childhood. Therefore, we investigated the cross-lagged associations between PA, motor performance, and academic skills from Grade 1 to Grade 3 in Finnish primary-school children. METHODS: A total of 189 children aged 6-9 years at baseline comprised the study sample. Total PA was assessed using a questionnaire filled out by parents, moderate-to-vigorous PA by combined heart rate and body movement monitor, motor performance by 10x5-metre shuttle run test, and academic skills by arithmetic fluency and reading comprehension tests in Grade 1 and Grade 3...

PURPOSE: The impact of physical impairment on Froude efficiency and intra-cyclic velocity fluctuation in Para swimmers is not well documented. Identification of differences in these variables between disabled and non-disabled swimmers could help develop a more objective system for assigning Para swimmers to classes for competition. This study quantifies Froude efficiency and intra-cyclic velocity fluctuation in unilateral forearm-amputee front crawl swimmers, and evaluates associations between these variables and performance...

INTRODUCTION: The hormonal withdrawal hypothesis suggests that reduction of progesterone in women following concussion may lead to greater symptom burden and longer recoveries. Current evidence indicates that hormonal stability following head injury may be an important moderator of post-concussive recovery. Thus, female athletes using hormonal contraceptives (HCs) may exhibit better recovery profiles as their hormone levels are artificially stabilized. Our investigation sought to examine the relation between HC use and concussion outcomes in female student-athletes...

INTRODUCTION: Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder for which behavioural treatments such as exercise are recommended as part of a multi-disciplinary treatment program. Exercise improves executive function in individuals with ADHD, but limited information exists regarding the mechanisms involved in the response. We examined task-evoked brain responses during exercise and seated rest in 38 adolescents (n = 15 ADHD; age = 13.6+/-1.9, male = 73...

PURPOSE: Assessment of trends in physical activity (PA) and sedentary time (ST) is important for evaluating the effectiveness of national policies and setting goals to improve population PA. This study describes changes in measured PA and ST through motion sensors of the Portuguese population from 2008 to 2018. METHODS: PA and ST were measured with accelerometry from individuals (≥10 yrs) participating in the 2008 (n = 4 532) and 2018 (n = 6 369) Portuguese PA Surveillance Systems...

PURPOSE: Numerous studies have implicated involvement of structure and function of the hippocampus in physical exercise, and the larger hippocampal volume is one of the relevant benefits reported in exercise. It remains to be determined that how the different subfields of hippocampus respond to physical exercise. METHODS: 3D T1-weighted magnetic resonance imaging were acquired in 73 amateur marathon runners (AMRs) and 52 healthy controls (HCs) matched with age, sex and education...

PURPOSE: To investigate associations between menstrual function, eating disorders, and risk of low energy availability with musculoskeletal injuries in British Servicewomen. METHODS: All women under 45 in the UK Armed Forces were invited to complete a survey about menstrual function, eating behaviours, exercise behaviours, and injury history. RESULTS: 3,022 women participated; 2% had a bone stress injury in the last 12 months, 20% had ever had a bone stress injury, 40% had a time-loss musculoskeletal injury in the last 12 months, and 11% were medically downgraded for a musculoskeletal injury...

PURPOSE: The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU). METHODS: Physically active participants were recruited into three groups: NM (n = 19), CU (n = 11), and PU (n = 12). Participants' HR and HRV (with Bodyguard 2 HRV monitor), and blood hormones were monitored during one menstrual cycle (MC) (NM-group) or for 4 weeks (CU and PU-groups)...

PURPOSE: A ketone body (β-hydroxybutyrate [β-HB]) is used as an energy source in the peripheral tissues. However, the effects of acute β-HB supplementation on different modalities of exercise performance remain unclear. This study aimed to assess the effects of acute β-HB administration on the exercise performance of rats. METHODS: In Study 1, Sprague Dawley rats were randomly divided into six groups: endurance exercise (EE + PL and EE + KE), resistance exercise (RE + PL and RE + KE), and high-intensity intermittent exercise (HIIE+PL and HIIE+KE) with placebo (PL) or β-HB salt (KE) administration...

INTRODUCTION/PURPOSE: To determine personal, environmental, and participation factors that predict children's physical activity (PA) trajectories from preschool through to school years. METHODS: 279 children (4.5 ± 0.9 years old, 52% boys) were included in this study. PA was collected via accelerometry at 6 different timepoints over 6.3 ± 0.6 years. Time stable variables were collected at baseline and included child's sex and ethnicity. Time dependent variables were collected at 6 timepoints (age, years) and included household income (CAD), parental total PA, parental influence on PA, and parent-reported child's quality of life, child's sleep, and child's amount of weekend outdoor PA...