The 50 most-cited articles in Medicine & Science in Sports & Exercise, 2024

ABSTRACT: Excessive body weight and adiposity contribute to many adverse health concerns. The American College of Sports Medicine (ACSM) recognizes that the condition of excess body weight and adiposity is complex, with numerous factors warranting consideration. The ACSM published a position stand on this topic in 2001 with an update in 2009, and a consensus paper on the role of physical activity in the prevention of weight gain in 2019. This current consensus paper serves as an additional update to those prior ACSM position and consensus papers. The ACSM supports the inclusion of physical activity in medical treatments (pharmacotherapy, metabolic and bariatric surgery) of excess weight and adiposity, as deemed to be medically appropriate, and provides perspectives on physical activity within these therapies. For weight loss and prevention of weight gain, the effects may be most prevalent when physical activity is progressed in an appropriate manner to at least 150 min·wk-1 of moderate-intensity physical activity, and these benefits occur in a dose-response manner. High-intensity…

INTRODUCTION: This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O 2max ) and submaximal thresholds. METHODS: Eighty-four young healthy participants (42 females, 42 males) were randomly assigned to six age, sex, and V̇O 2max -matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention. RESULTS: Compared with the change in V̇O 2max (∆V̇O 2max ) in CON (0.1 ± 1.2 mL·kg -1 ·min -1 ), all training groups, except MOD (1.8 ± 2.7 mL·kg -1 ·min -1 ), demonstrated a significant increase ( P < 0.05). HIIT…

PURPOSE: This study aimed to investigate the effect of the MC and endogenous sex hormone concentrations on performance-determining variables in three distinct MC phases in endurance-trained females. METHODS: Twenty-one eumenorrheic trained/highly trained endurance athletes completed a standardized test battery during the early follicular phase (EFP), ovulatory phase (OP), and midluteal phase (MLP) for either one ( n = 7) or two test cycles ( n = 14). MC phases were determined using calendar-based counting, urinary ovulation testing, and verified with serum hormone analysis. MCs were retrospectively classified as eumenorrheic or disturbed. Disturbed MCs were excluded from analysis. The test battery consisted of 4-6 × 5-min submaximal stages with stepwise speed increases, a 30-s all-out double-poling ski ergometer test, and a maximal incremental treadmill running test. RESULTS: At a group level, there was no effect of MC phase or the serum concentrations of estrogen and progesterone on peak oxygen uptake (V̇O 2peak ), oxygen uptake at 4 mmol·L -1 blood lactate concentration, time to…

PURPOSE: The aim of the study was to assess the influence of menstrual cycle phase on injury incidence, severity, and type in elite female professional footballers over three seasons. METHODS: Time-loss injuries and menstrual cycle data were prospectively recorded for 26 elite female football players across three seasons. The menstrual cycle was categorized into four phases using a standardized model: menstruation (phase 1; P1), remainder of follicular phase (phase 2; P2), early luteal (phase 3; P3), and premenstrual phase (phase 4; P4). Injury incidence rates (IIR) and ratios (IIRR) were calculated for overall injuries, injury severity, type, contact vs noncontact, and game/training. RESULTS: A total of 593 cycles across 13,390 d were tracked during the study, and 74 injuries from 26 players were eligible for analysis. When comparing IIR between phases (reference: P1), overall injury rates were highest in P4 (IIRR, 2.30 (95% confidence interval, 0.99-5.34; P = 0.05)). When examining rates by injury severity and type, IIR values were also highest in P4 for ≤7 d' time-loss (4.40…

INTRODUCTION: The hamstring muscles play a crucial role in sprint running but are also highly susceptible to strain injuries, particularly within the biceps femoris long head (BFlh). This study compared the adaptations in muscle size and strength of the knee flexors, as well as BFlh muscle and aponeurosis size, after two eccentrically focused knee flexion training regimes: Nordic hamstring training (NHT) vs lengthened state eccentric training (LSET, isoinertial weight stack resistance in an accentuated hip-flexed position) vs habitual activity (no training controls: CON). METHODS: Forty-two healthy young males completed 34 sessions of NHT or LSET over 12 wk or served as CON ( n = 14/group). Magnetic resonance imaging-measured muscle volume of seven individual knee flexors and BFlh aponeurosis area, and maximum knee flexion torque during eccentric, concentric, and isometric contractions were assessed pre- and post-training. RESULTS: LSET induced greater increases in hamstrings (+18% vs +11%) and BFlh (+19% vs +5%) muscle volumes and BFlh aponeurosis area (+9% vs +3%) than NHT (all P…

INTRODUCTION: Running economy (RE) deteriorates during prolonged running, although the effect of measuring energy cost (EC) or oxygen cost (OC) on the magnitude of these changes has not been investigated. Similarly, it is unknown if runners' performance level may influence the deterioration of RE during prolonged running. The aims of this study were to compare changes in EC and OC measurements of RE during a prolonged run in a large cohort of well-trained male runners, and to compare changes between runners of high- and low-performance standard. METHODS: Forty-four male runners (maximal oxygen uptake (V̇O 2max ) 62.4 mL·kg -1 ·min -1 ; 10-km time: 35:50 ± 4:40 mm:ss) completed an incremental test determining lactate threshold 1 (LT1) and V̇O 2max , and on a separate occasion, a 90-min run at LT1. Respiratory gases were collected at 15-min intervals. Subsequently, subgroups of high- (HP; 10-km time: 31:20 ± 01:00 mm:ss) and low-performing (LP; 10-km time: 41:50 ± 01:20 mm:ss) runners were compared. RESULTS: RE deterioration was only fractionally larger when expressed as OC than EC…

PURPOSE: Step count is an intuitive measure of physical activity frequently quantified in health-related studies; however, accurate step counting is difficult in the free-living environment, with error routinely above 20% in wrist-worn devices against camera-annotated ground truth. This study aimed to describe the development and validation of step count derived from a wrist-worn accelerometer and assess its association with cardiovascular and all-cause mortality in a large prospective cohort. METHODS: We developed and externally validated a self-supervised machine learning step detection model, trained on an open-source and step-annotated free-living dataset. Thirty-nine individuals will free-living ground-truth annotated step counts were used for model development. An open-source dataset with 30 individuals was used for external validation. Epidemiological analysis was performed using 75,263 UK Biobank participants without prevalent cardiovascular disease (CVD) or cancer. Cox regression was used to test the association of daily step count with fatal CVD and all-cause mortality…

PURPOSE: Cardiorespiratory fitness (CRF) measured by peak oxygen consumption (V̇O 2peak ) declines with aging and correlates with mortality and morbidity. Cardiopulmonary exercise testing (CPET) is the criterion method to assess CRF, but its feasibility, validity, and reliability in older adults are unclear. Our objective was to design and implement a dependable, safe, and reliable CPET protocol in older adults. METHODS: V̇O 2peak was measured by CPET, performed using treadmill exercise in 875 adults ≥70 yr in the Study of Muscle, Mobility and Aging (SOMMA). The protocol included a symptom-limited peak (maximal) exercise and two submaximal walking speeds. An adjudication process was in place to review tests for validity if they met any prespecified criteria (V̇O 2peak <12.0 mL·kg -1 ·min -1 ; maximum heart rate <100 bpm; respiratory exchange ratio <1.05 and a rating of perceived exertion <15). A subset ( N = 30) performed a repeat test to assess reproducibility. RESULTS: CPET was safe and well tolerated, with 95.8% of participants able to complete the V̇O 2peak phase of the…

BACKGROUND: Blood flow restriction training (BFRT) is a popular rehabilitation intervention after anterior cruciate ligament reconstruction (ACLR). However, there are a lack of clinical trials establishing the efficacy of using BFRT during rehabilitation to improve quadriceps muscle function. PURPOSE: The purpose of this study is to evaluate the efficacy of blood flow restriction training to improve quadriceps muscle strength, morphology, and physiology, and knee biomechanics in individuals after ACLR in a double-blind, randomized, placebo-controlled clinical trial (NCT03364647). METHODS: Forty-eight athletes (20 females/28 males) were randomly assigned to low-load strength training with active BFRT or standard of care strength training with a sham unit. Treatment occurred for 1-month pre-surgery and 4 to 5 months post-surgery with both groups following the same standard rehabilitation protocol. Outcome variables were measured at baseline and 4 to 5 months post-surgery. Quadriceps muscle strength (isometric and isokinetic peak torque and rate of torque development) was measured on…

PURPOSE: Whey protein ingestion is typically considered an optimal dietary strategy to maximize myofibrillar protein synthesis (MyoPS) after resistance exercise. Although single-source plant protein ingestion is typically less effective, at least partly, due to less favorable amino acid profiles, this could theoretically be overcome by blending plant-based proteins with complementary amino acid profiles. We compared the postexercise MyoPS response after the ingestion of a novel plant-derived protein blend with an isonitrogenous bolus of whey protein. METHODS: Ten healthy, resistance-trained, young adults (male/female: 8/2; age: 26 ± 6 yr; BMI: 24 ± 3 kg·m -2 ) received a primed continuous infusion of L-[ ring - 2 H 5 ]-phenylalanine and completed a bout of bilateral leg resistance exercise before ingesting 32 g protein from whey (WHEY) or a plant protein blend (BLEND; 39.5% pea, 39.5% brown rice, 21.0% canola) in a randomized, double-blind crossover fashion. Blood and muscle samples were collected at rest, and 2 and 4 h after exercise and protein ingestion, to assess plasma amino…

PURPOSE: To understand athletic performance before and after puberty, this study determined 1) the age at which the sex difference increases among elite youth track and field athletes for running and jumping events, and 2) whether there is a sex difference in performance before ages associated with puberty among elite youth athletes. METHODS: Track and field records of elite US male and female youth (7-18 yr) across 3 yr (2019, 2021, and 2022) were collected from an online database ( athletic.net ). The top 50 performances were recorded for 100-, 200-, 400-, and 800-m track running, long jump, and high jump. RESULTS: Males ran faster than females at every age in the 100, 200, 400 and 800 m ( P < 0.001). When combining all running events, the sex difference (%) was 4.0% ± 1.7% between 7 and 12 yr and increased to 6.3% ± 1.1% at 13 yr and 12.6% ± 1.8% at 18 yr ( P < 0.001). Similarly, males jumped higher and farther than females at every age ( P < 0.001). For long jump, the sex difference was 6.8% ± 2.8% between 7 and 12 yr, increasing to 8.5% ± 1.7% at 13 yr and 22.7% ± 1.4% at 18 yr…

PURPOSE: The objective of this study is to evaluate the concordance of predicted maturity status classifications (pre-, circa-, or post-peak height velocity (PHV)) relative to observed age at PHV in youth soccer players. METHODS: Longitudinal height records for 124 male soccer players were extracted from academy records spanning the 2000 to 2022 seasons. Age at PHV for each player was estimated with the Superimposition by Translation and Rotation model. Players were classified as pre-, circa-, or post-PHV using both ±1- and ±0.5-yr criteria to define the circa-PHV interval. Maturity status was estimated with several prediction protocols: maturity offset (Mirwald, Moore-1, Moore-2), maturity ratio (Fransen), and percentage of predicted adult height (PAH%) using the Khamis-Roche and Tanner-Whitehouse 2 equations using several bands: 85% to 96%, 88% to 96%, 88% to 93%, and 90% to 93% for the circa-PHV interval, and visual evaluation of individual growth curves alone or with PAH% based on Khamis-Roche and Tanner-Whitehouse 2. Concordance of maturity status classifications based on…

ABSTRACT “Super-shoes” are designed to improve endurance running performance by reducing the metabolic demands of running. Although the research on “super-shoes” is still developing and has mostly been studied in male runners, it is not clear how possible mediating factors, such as foot strike pattern, influence the metabolic cost and joint mechanics in competitive female runners. Purpose The objective of this study is to assess the influence of “super-shoes” on metabolic cost and joint mechanics in competitive female runners and to understand how foot strike pattern may influence the footwear effects. Methods Eighteen competitive female runners ran four 5-min bouts on a force instrumented treadmill at 12.9 km·h −1 in 1) Nike Vaporfly Next% 2™ (SUPER) and 2) Nike Pegasus 38™ (CON) in a randomized and mirrored order. Results Metabolic power was improved by 4.2% ( P < 0.001; d = 0.43) and metatarsophalangeal (MTP) negative work ( P < 0.001; d = 1.22), ankle negative work ( P = 0.001; d = 0.67), and ankle positive work ( P < 0.001; d = 0.97) were all smaller when running in SUPER…

INTRODUCTION: Objectively measured physical activity (PA) is a modifiable risk factor for mortality. Understanding the predictive performance of PA is essential to establish potential targets for early intervention to reduce mortality among older adults. METHODS: The study used a subset of the National Health and Nutrition Examination Survey (NHANES) 2011-2014 data consisting of participants 50 to 80 yr old ( n = 3653, 24297.5 person-years of follow-up, 416 deaths). Eight accelerometry-derived features and 14 traditional predictors of all-cause mortality were compared and ranked in terms of their individual and combined predictive performance using the 10-fold cross-validated concordance (C) from Cox regression. RESULTS: The top 3 predictors of mortality in univariate analysis were PA related: average Monitor-Independent Movement Summary (MIMS) in the 10 most active hours (C = 0.697), total MIMS per day (C = 0.686), and average log-transformed MIMS in the most 10 active hours of the day (C = 0.684), outperforming age (C = 0.676) and other traditional predictors of mortality. In…

PURPOSE: To examine the relationship between menstrual cycle (MC) phase-dependent fluctuations of estrogen and progesterone and virtual cycling race performance, with a secondary aim of correlating perceived MC-related symptoms with performance. METHODS: In a novel observational study design, 37 female cyclists/triathletes not using any hormonal contraception completed one virtual cycling race (19.5-km time trial (TT)) per week across a 1-month period (totaling four races). Participants completed MC characterization and tracking, including urinary ovulation kits, across two complete MCs. Venous blood samples were collected within 21 h of racing to determine serum 17-β-estradiol and progesterone concentrations, as well as an assessment of self-reported, perceived race-day MC and gastrointestinal (GI) symptoms, which were all then correlated to race performance. RESULTS: There was no relationship between race completion time and individual estradiol ( r = -0.001, P = 0.992) or progesterone ( r = -0.023, P = 0.833) concentrations. There was no difference between race time between MC…

PURPOSE: Prior evidence has shown that neural factors contribute to the loss of muscle force after skeletal muscle disuse. However, little is known about the specific neural mechanisms altered by disuse. Persistent inward current (PIC) is an intrinsic property of motoneurons responsible for prolonging and amplifying the synaptic input, proportionally to the level of neuromodulation, thus influencing motoneuron discharge rate and force production. Here, we hypothesized that short-term unilateral lower limb suspension (ULLS) would reduce the neuromodulatory input associated with PIC, contributing to the reduction of force generation capacity. In addition, we tested whether physical exercise would restore the force generation capacity by reestablishing the initial level of neuromodulatory input. METHODS: In 12 young adults, we assessed maximal voluntary contraction pre- and post-10 d of ULLS and after 21 d of active recovery (AR) based on resistance exercise. PIC was estimated from high-density surface electromyograms of the vastus lateralis muscle as the delta frequency (Δ F ) of…

INTRODUCTION: Wearables have the potential to provide accurate estimates of tissue loads at common running injury locations. Here we investigate the accuracy by which commercially available instrumented insoles (ARION; ATO-GEAR, Eindhoven, The Netherlands) can predict musculoskeletal loading at common running injury locations. METHODS: Nineteen runners (10 males) ran at five different speeds, four slopes, with different step frequencies, and forward trunk lean on an instrumented treadmill while wearing instrumented insoles. The insole data were used as input to an artificial neural network that was trained to predict the Achilles tendon strain, and tibia and patellofemoral stress impulses and weighted impulses (damage proxy) as determined with musculoskeletal modeling. Accuracy was investigated using leave-one-out cross-validation and correlations. The effect of different input metrics was also assessed. RESULTS: The neural network predicted tissue loading with overall relative percentage errors of 1.95 ± 8.40%, -7.37 ± 6.41%, and -12.8 ± 9.44% for the patellofemoral joint, tibia,…

BACKGROUND: Skeletal muscle loss is prevalent throughout the cancer continuum and correlated with morbidity and mortality. Resistance exercise has been trialed to mitigate skeletal muscle loss. This systematic review summarizes and qualitatively synthesizes the effects of resistance exercise on muscle-related outcomes in adult cancer populations, including skeletal muscle mass, performance and muscle-related biomarkers. METHODS: The systematic review protocol was developed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). We searched electronic databases including AMED, CENTRAL, CINAHL, CIRRIE, EMBASE, MEDLINE, PEDro, REHABDATA, Scopus, and SPORTDiscus from inception to December 2021. We included randomized controlled trials that investigated the effects of resistance exercise on muscle-related outcomes in adult cancer populations. Interventions that involved any resistance exercise were included. Muscle-related outcomes were categorized as skeletal muscle mass (e.g., lean mass, appendicular muscle mass), muscle…

INTRODUCTION: Conflicting results have been reported on the functional role of the proximal and distal compartments of the semitendinosus (ST) muscle. This study compared the discharge characteristics of motor units (MU) in the two compartments at three knee joint angles (0°: long length; 45°: intermediate length; and 90°: short length). METHODS: Twenty men (21.4 ± 2.3 yr) performed steady isometric contractions with the knee flexors at four target forces: 10%, 20%, 40%, and 60% of maximum voluntary contraction. High-density EMG signals were recorded to examine the MU discharge characteristics in the two compartments. Measurements included recruitment threshold, mean discharge rate, coefficient of variation (CoV) for interspike interval, and SD of filtered cumulative spike train (fCST). Additionally, the within- and between-compartment association of the neural drive was calculated. RESULTS: ANOVA indicated that maximal force, absolute EMG amplitude during the maximum voluntary contractions, and force steadiness (CoV for force) were greater at the longest muscle length than the…

Background: Hamstring strain injuries are associated with significant time away from sport and high reinjury rates. Recent evidence suggests that hamstring injuries often occur during accelerative running, but investigations of hamstring mechanics have primarily examined constant speed running on a treadmill. To help fill this gap in knowledge, this study compares hamstring lengths and lengthening velocities between accelerative running and constant speed overground running. Methods: We recorded 2 synchronized videos of 10 participants (5 female, 5 male) during 6 accelerative running trials and 6 constant speed running trials. We used OpenCap (a markerless motion capture system) to estimate body segment kinematics for each trial and a 3-dimensional musculoskeletal model to compute peak length and step-average lengthening velocity of the biceps femoris (long head) muscle-tendon unit. To compare running conditions, we used linear mixed regression models with running speed (normalized by the subject-specific maximum) as the independent variable. Results: At running speeds below 75% of…

INTRODUCTION: Low cardiorespiratory fitness (CRF) increases the risk of cardiovascular disease by up to eightfold and is one of the strongest predictors of mortality. Some studies demonstrate impaired CRF in people living with type 1 and type 2 diabetes compared with those without diabetes, whereas others demonstrate no diabetes-associated impairment in CRF. PURPOSE: We aimed to determine whether diabetes can influence CRF and, if so, identify clinical associations underlying diabetes-associated exercise impairments. METHODS: Sixty-eight studies were included in the quantitative analysis. Standardized mean difference (SMD) was calculated and meta-analyses and meta-regressions were performed by using a random-effects model. RESULTS: Diabetes is associated with a large negative effect on CRF (SMD = -0.80, P < 0.001)-an effect that is partially mitigated, but still significant, in those with high physical activity levels (SMD = -0.50, P = 0.007). A sedentary lifestyle (SMD = -0.83, P = 0.007) and the presence of clinical complications related to diabetes (SMD = -1.66, P < 0.001)…

PURPOSE: Motion capture technology is quickly evolving, providing researchers, clinicians, and coaches with more access to biomechanics data. Markerless motion capture and inertial measurement units (IMUs) are continually developing biomechanics tools that need validation for dynamic movements before widespread use in applied settings. This study evaluated the validity of a markerless motion capture, IMU, and red, green, blue, and depth (RGBD) camera system as compared with marker-based motion capture during countermovement jumps, overhead squats, lunges, and runs with cuts. METHODS: Thirty adults were recruited for this study (sex: 18 females, 12 males; age: 25.4 ± 8.6 yrs; height: 1.71 ± 0.08 m; weight: 71.6 ± 11.5 kg). Data were collected simultaneously with four motion capture technologies (i.e., Vicon, marker-based; Theia/Optitrack, markerless; APDM Opals, IMUs; and Vald HumanTrak, RGBD camera). System validity for lower and upper body joint angles was evaluated using bias, root mean squared error (RMSE), precision, maximum absolute error, and intraclass correlation…

INTRODUCTION: Resting energy expenditure (REE) may fluctuate during the menstrual cycle (MC), due to the physiological effects of estradiol (E2) and progesterone. This study examined changes in REE and metabolic hormones (leptin, ghrelin, thyroid hormones), and dietary intake in two hormonally distinct groups, naturally menstruating women (NoOC) and women using monophasic combined oral contraceptives (COC). METHODS: Measurements included REE by indirect calorimetry, body composition by bioimpedance, and blood samples for hormone analysis in the early follicular and midluteal phases of the MC in the NoOC group ( n = 38) or the active and inactive phases of the COC cycle (COC; n = 19). Participants recorded their food intake for 3 d after measurements. A secondary analysis was completed for the NoOC group without REE outliers (difference between measurements >1.5 × interquartile range, n = 4). RESULTS: In the NoOC group, luteal phase REE was 40 kcal higher than follicular phase REE (95% confidence interval (CI), -2 to 82 kcal·d -1 , d = 0.20, P = 0.061). Leptin ( d = 0.35, P < 0.001),…

INTRODUCTION: The study aimed to investigate to what extent acute endurance exercise, especially eccentric exercise and cardiorespiratory fitness, affects the metabolic profile of CD4 + cells. METHODS: Fifteen male, healthy adults aged between 20 and 33 yr with a maximal oxygen uptake (V̇O 2max ) between 44 and 63 mL·kg -1 ·min -1 performed a downhill run (DR) and a level run (LR) for 45 min at 70% of their V̇O 2max on a treadmill in a crossover design. Blood samples were taken before (T0), directly after (T1), 3 h after (T3), and 24 h (T24) after each exercise for analyzing leukocyte numbers and cytokine levels. Isolated CD4 + cells were incubated for 4 h in autologous resting versus 3 h after exercise serum (T3 DR and T3 LR), and subsequently, cellular respiration, transcriptomic, and metabolomics profiles were measured. RESULTS: The systemic immune inflammation index increased significantly after DR and LR at T1 and T3 ( P < 0.001). In contrast, the transcriptomic and metabolic profile of CD4 + cells showed no significant alterations after incubation in T3 exercise serum.…

INTRODUCTION: Evidence suggests that acute exercise benefits inhibitory control, but it remains unclear how physical and cognitive load influence this ability in preadolescent children, when faced with different types of distractors. We examined their moderating effects along with changes in prefrontal cortex hemodynamics. METHODS: Using a crossover design, 29 participants completed 10 min of exercise (with an interactive training wall) at 1) low physical and low cognitive load, 2) low physical and high cognitive load, 3) high physical and low cognitive load, and 4) high physical and high cognitive load in a randomized order. Before and after each condition, they performed a Standard and Affective Stroop task. During both tasks, the lateral oxygenation difference in the prefrontal cortex was measured by using functional near-infrared spectroscopy. RESULTS: For the Standard Stroop task, there was no effect of physical and cognitive load on performance. In contrast, exercise with low compared with high cognitive load was associated with a greater reduction of reaction time and…

PURPOSE: Understanding muscle-tendon forces (e.g., triceps surae and Achilles tendon) during locomotion may aid in the assessment of human performance, injury risk, and rehabilitation progress. Shear wave tensiometry is a noninvasive technique for assessing in vivo tendon forces that has been recently adapted to a wearable technology. However, previous laboratory-based and outdoor tensiometry studies have not evaluated running. This study was undertaken to assess the capacity for shear wave tensiometry to produce valid measures of Achilles tendon loading during running at a range of speeds. METHODS: Participants walked (1.34 m·s -1 ) and ran (2.68, 3.35, and 4.47 m·s -1 ) on an instrumented treadmill while shear wave tensiometers recorded Achilles tendon wave speeds simultaneously with whole-body kinematic and ground reaction force data. A simple isometric task allowed for the participant-specific conversion of Achilles tendon wave speeds to forces. Achilles tendon forces were compared with ankle torque measures obtained independently via inverse dynamics analyses. Differences in…

PURPOSE: High-intensity interval training (HIIT) can efficiently decrease total and (intra-)abdominal fat mass (FM); however, the effects of running versus cycling HIIT programs on FM reduction have not been compared yet. In addition, the link between HIIT-induced FM reduction and gut microbiota must be better investigated. The aim of this study was to compare the effects of two 12-wk HIIT isoenergetic programs (cycling vs running) on body composition and fecal microbiota composition in nondieting men with overweight or obesity. METHODS: Sixteen men (age, 54.2 ± 9.6 yr; body mass index, 29.9 ± 2.3 kg·m -2 ) were randomly assigned to the HIIT-BIKE (10 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) or HIIT-RUN (9 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) group (3 times per week). Dual-energy x-ray absorptiometry was used to determine body composition. Preintervention and postintervention fecal microbiota composition was analyzed by 16S rRNA gene sequencing, and diet was controlled. RESULTS: Overall, body weight, and abdominal and visceral FM…

OBJECTIVE: This study aimed to investigate differences in cortical activation between individuals with and without chronic ankle instability (CAI) during a dorsi-plantarflexion task and further explore its association with sensorimotor function. METHODS: In this cross-sectional study, 62 participants were recruited, including 31 adults with CAI and 31 healthy adults. Sensorimotor functions, including joint position sense and force sense, were tested using absolute error associated with joint position reproduction and force reproduction tasks. A block design was used to collect task-state functional magnetic resonance imaging by using a custom-built, Magnetic resonance imaging-compatible device during a dorsi-plantarflexion task. RESULTS: Individuals with CAI showed significantly worse joint position sense and force sense in all four movement directions than those without CAI. Chronic ankle instability is significantly associated with lower cortical activation in the sensorimotor network, mainly including the right postcentral gyrus, right supplementary motor area (SMA) and left…

BACKGROUND: Sleeping at altitude is highly common in athletes as an integral part of altitude training camps or sport competitions. However, concerns have been raised because of expected negative effects on sleep quality, thereby potentially hampering exercise recovery and next-day exercise performance. We recently showed that ketone ester (KE) ingestion beneficially impacted sleep after strenuous, late evening exercise in normoxia, and alleviated hypoxemia. Therefore, we hypothesized that KE ingestion may be an effective strategy to attenuate hypox(em)ia-induced sleep dysregulations. METHODS: Eleven healthy male participants completed three experimental sessions including normoxic training and subsequent sleep in normoxia or at a simulated altitude of 3000 m while receiving either KE or placebo postexercise and presleep. Sleep was evaluated using polysomnography, whereas next-day exercise performance was assessed through a 30-min all-out time trial (TT 30' ). Physiological measurements included oxygen status, heart rate variability, ventilatory parameters, blood acid-base balance,…

PURPOSE: Resistance training may be empirically believed to increase passive muscle stiffness. Meanwhile, a recent study showed that the passive stiffness of a specific hamstring muscle acutely decreased after eccentric-only resistance exercise at long muscle lengths with a long contraction duration (LL). To extend this finding, the present study investigated the chronic effects of eccentric-only resistance training with LL at different weekly frequencies on the passive stiffness of the biarticular hamstring muscles. METHODS: Thirty-six healthy young males were assigned into two training groups with two and three weekly sessions (W2 and W3; n = 12, respectively) and a control group (CON; n = 12). The participants in both training groups performed eccentric-only stiff-leg deadlift at 50%-100% of exercise range of motion (0% = upright position) with 5 s per repetition for 10 wk. Before and after the intervention period, the shear moduli of the biarticular hamstring muscles, maximal voluntary isometric torque of knee flexion, and volumes of the individual hamstring muscles were…

INTRODUCTION: Increases in skeletal muscle size occur in response to prolonged exposure to resistance training that is typically ascribed to increased muscle fiber size. Whether muscle fiber number also changes remains controversial, and a paucity of data exists about myofibrillar structure. This cross-sectional study compared muscle fiber and myofibril characteristics in long-term resistance-trained (LRT) versus untrained (UNT) individuals. METHODS: The maximal anatomical cross-sectional area (ACSAmax) of the biceps brachii muscle was measured by magnetic resonance imaging in 16 LRT (5.9 ± 3.5 yr' experience) and 13 UNT males. A muscle biopsy was taken from the biceps brachii to measure muscle fiber area, myofibril area, and myosin spacing. Muscle fiber number, and myofibril number in total and per fiber were estimated by dividing ACSAmax by muscle fiber area or myofibril area, and muscle fiber area by myofibril area, respectively. RESULTS: Compared with UNT, LRT individuals had greater ACSAmax (+70%, P < 0.001), fiber area (+29%, P = 0.028), fiber number (+34%, P = 0.013), and…

BACKGROUND: Arduous military training frequently consists of prolonged physical activity, sleep disturbance, and stress that increases musculoskeletal injury risk and performance decrements. Inflammatory and oxidative stress responses have been reported in response to arduous training, but with inconsistencies across markers and with underrepresentation of women. The purpose of the current report was to measure circulating inflammation and oxidative stress responses to military training and to correlate biomarkers with subjective measures of stress and sleep quality as well as military fitness test performance. METHODS: Candidates undergoing the 10-wk Marine Corps Officer Candidate School (OCS; 101 men, 62 women) were monitored, with demographic and questionnaire data collected, and blood drawn before and after OCS. Blood was analyzed for six markers of inflammation and three markers of oxidative stress. Associations between biomarkers and questionnaire and fitness test performance were tested. RESULTS: All measured inflammatory markers as well as plasma antioxidant capacity were…

PURPOSE: Vigorous intermittent lifestyle physical activity (VILPA) are bursts of incidental vigorous activity that occur during day-to-day activities outside of the exercise-domain. Vigorous intermittent lifestyle physical activity has shown promise in lowering risk of mortality and chronic disease. However, there is an absence of an empirically derived definition. Using physiological and effort-based metrics commonly used to define vigorous intensity, we investigated the minimum time needed to elicit physiological and perceived exertion responses to standardized activities of daily living. METHODS: Seventy adults (age = 58.0 ± 9.6 yr; 35 female) completed 9 VILPA activities of daily living in a randomized order, which included fast walking, fast incline walking, stair climbing, stationary cycling, and carrying external weight equal to 5% and 10% of body weight. Metabolic rate (by continuous indirect calorimetry), heart rate (telemetry) and perceived effort (Borg Scale) were measured during exercise. Time to reach VILPA was assessed using %V̇O 2max , %HRmax, and rating of perceived…

INTRODUCTION: Overuse musculoskeletal injuries (MSKI) remain a significant medical challenge in military personnel undergoing military training courses; further understanding of the biological process leading to overuse MSKI development and biological signatures for injury risk are warranted. The purpose of this study was to determine the association between overuse MSKI occurrence and physiological characteristics of allostatic load characterized as maladaptive biological responses to chronic stress measured by wearable devices in US Marine Corps officer candidates during a 10-wk training course. METHODS: Devices recorded energy expenditure (EE), daytime heart rate (HR), sleeping HR, and sleep architecture (time and percentage of deep, light, rapid eye movement sleep, awake time, total sleep). Flux was calculated as the raw or absolute difference in the average value for that day or night and the day or night beforehand. Linear mixed-effect model analysis accounting for cardiorespiratory fitness assessed the association between overuse MSKI occurrence and device metrics ( α =…

INTRODUCTION: Twenty-four-hour movement behaviors: moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior (SB), and sleep are crucial factors affecting older adults' health. Using a compositional data analysis approach, this study examined the associations of time spent in these four movement behaviors with cardiometabolic health, physical fitness, and mental health among older adults. Furthermore, this study identified the estimated changes in aforementioned health outcomes by reallocating SB time to other movement behaviors. METHODS: A population-based cross-sectional study of 4562 participants (67.68 ± 5.03 yr; 55.8% female) were implemented in Hubei China between July 25 and November 19, 2020. Measures included demographics, movement behaviors, cardiometabolic indicators (body mass index, waist circumference, waist-hip ratio, percentage body fat, systolic and diastolic blood pressure), physical fitness, and mental health outcomes (depressive symptoms and loneliness). Compositional data analyses were implemented in R. RESULTS: MVPA and…

BACKGROUND: Resistance training confers numerous health benefits that are mediated in part by circulating factors. Toward an enhanced molecular understanding, there is growing interest in a class of signaling biomarkers called extracellular vesicles (EV). EVs support physiological adaptations to exercise by transporting their cargo (e.g., microRNA (miRNA)) to target cells. Previous studies of changes in EV cargo have focused on aerobic exercise, with limited data examining the effects of resistance exercise. We examined the effect of acute resistance exercise on circulating EV miRNAs and their predicted target pathways. METHODS: Ten participants (5 men; age, 26.9 ± 5.5 yr; height, 173.4 ± 10.5 cm; body mass, 74.0 ± 11.1 kg; body fat, 25.7% ± 11.6%) completed an acute heavy resistance exercise test (AHRET) consisting of six sets of 10 repetitions of back squats using 75% one-repetition maximum. Pre-/post-AHRET, EVs were isolated from plasma using size exclusion chromatography, and RNA sequencing was performed. Differentially expressed miRNAs between pre- and post-AHRET EVs were…

PURPOSE: Obesity may blunt exercise responsiveness to improve muscular adaptations. The effect of resistance training (RT) targeting different body regions on muscle and inflammatory markers is unclear. This study aimed to investigate the impact of upper (upper body exercises), lower (lower body exercises), or combined (upper body + lower body exercises) RT on muscle and inflammatory markers, body composition, and performance in overweight and obese men. METHODS: Sixty overweight and obese men (age, 31 ± 4 yr) were randomly assigned to one of four groups: upper-body RT (UB; n = 15), lower-body RT (LB; n = 15), combined RT (UB + LB; n = 15), or control (C; n = 15). The training protocol consisted of three exercise sessions per week for 12 wk. Blood samples for measuring serum markers (follistatin, myostatin, C-reactive protein (CRP), adiponectin, tumor necrosis factor α (TNF-α), and irisin) were obtained at baseline and 48 h after the final training session. Fat mass (FM), body fat percentage, skeletal muscle mass (SMM), and fat-free mass were measured using bioelectrical impedance…

PURPOSE: Aging is associated with declines in cognition and mental health that might be ameliorated by physical activity (PA). Dance integrates multiple physical, cognitive, and social elements, and might be an avenue for improving cognition and mood. This systematic review and meta-analysis examined the effects of formal and traditional dance on cognition, depression, and anxiety in older adults. METHODS: Five database searches yielded 17 randomized control trials (RCTs). RCTs were included if participants were ≥60 yr and healthy or living with mild cognitive impairment. We examined interventions of dance against any comparison group. Records were independently screened, and data were extracted by two reviewers. We performed random-effects models using robust variance estimation and tested individual treatment, study, and outcome-level moderators using the approximate Hotelling-Zhang test. RESULTS: Seventeen RCTs were included in the systematic review, but 13 RCTs were included in the meta-analysis, which included 1174 participants with a mean age of 70.7 yr, and 66.3% were female.…

PURPOSE: Females typically present with a higher prevalence of knee osteoarthritis (KOA), and such a higher prevalence may be due to unique knee biomechanics during walking. However, the sex-dependent ambulatory mechanics has been yet to be clarified. To address this critical knowledge gap, this study implemented a series of computational approaches 1) to identify sex-related knee joint biomechanics during ambulation in persons with KOA and 2) to compare these biomechanical measures between individuals with versus without KOA, stratified by sex. METHODS: We searched five electronic databases for studies reporting sex-specific knee biomechanics in persons with and/or without KOA. Summary estimates were computed using random-effects meta-analysis and stratified by sex. RESULTS: The systematic review identified 18 studies (308 males and 383 females with KOA; 740 males and 995 females without KOA). A series of meta-analyses identified female-specific knee biomechanics in a disease-dependent manner. Females with KOA had lower first peak knee adduction moment and peak knee adduction…

PURPOSE: The purpose of this study is to compare the effects of 8 wk of no intervention (CON), lower limb heat therapy (HEAT), moderate-intensity exercise training (EX), or combined training and therapy (HEATEX) in young, healthy recreationally active adults. METHODS: Sixty participants (23 ± 3 yr, 30 females) were randomly allocated into CON ( n = 15), HEAT ( n = 15), EX ( n = 14), or HEATEX ( n = 16). The primary outcome was vascular function, assessed through brachial artery flow-mediated dilation tests. Secondary measures included arterial stiffness (pulse wave velocity), cardiorespiratory fitness (V̇O 2peak ), body composition, and quadriceps muscle strength. RESULTS: There were no differences in brachial artery flow-mediated dilation between the groups before and after the interventions (all P > 0.05). Both interventions with a heating component were associated with within-group reductions in carotid-femoral pulse wave, and increase in absolute and relative V̇O 2peak after 8 wk (HEAT: ∆-0.27 [-0.53, -0.02] m s -1 , ∆0.18 [0.06, 0.29] L·min -1 , ∆2.18 [0.60, 3.76] mL·kg -1 ·min…

INTRODUCTION: In spite of the evolving participation of transgender adults in exercise and sports, research investigating the physical fitness of transgender women remains scarce in the scientific literature. METHODS: In this cross-sectional study, a variety of reference standard measures of physical fitness of transgender women who had undergone gender-affirming orchiectomy (30 ± 4 yr; n = 15) and who had not (27 ± 4 yr: n = 15) were compared with reference males (28 ± 5 yr; n = 15) and reference females (29 ± 5 yr; n = 15) who were matched for age and estimated physical activity level. Transgender women had been undergoing feminizing gender-affirming therapy for 8 to 10 yr. RESULTS: Height and lean mass of arms, legs, and trunk (measured via dual-energy x-ray absorptiometry) of transgender women were greater than those of reference females but lower than those of reference males (all P < 0.05). No significant differences were found in isokinetic muscular torque between reference females and transgender women. Both absolute and relative measures of maximal oxygen consumption were…

PURPOSE: In recent years, there has been significant advancement in the guidelines for recovery protocols involving heat or cold water immersion. However, comparison between the effects of hot and cold water immersion on key markers of neuromuscular recovery following exercise-induced muscle damage (EIMD) is lacking. METHODS: Thirty physically active males completed an individualized and tailored EIMD protocol immediately followed by one of the following recovery interventions: cold water immersion (11°C, CWI 11 ), hot water immersion (41°C, HWI 41 ), or warm-bath control (36°C, CON 36 ). Gastrointestinal temperature was tracked throughout HWI 41 . Knee extensors' maximal isokinetic strength (peak torque ( Tpeak )) and explosive strength (late-phase rate of force development (RFD 100-200 )) were measured before EIMD (pre-), 24 h (post-24 h), and 48 h (post-48 h) post-EIMD. In addition, pressure pain threshold (PPT) was measured to quantify the recovery from muscle soreness. Surface electromyography signals (sEMG) from the vastus lateralis were captured to extract the rates of…

PURPOSE: The aim of this study was to compare the physiological adaptations of males and females to repeated sprint training in hypoxia (RSH). METHODS: Active males and females completed 7 wk of repeated sprint training in normoxia (RSN; F i O 2 = 0.209, males: n = 11, females: n = 8) or RSH (F i O 2 = 0.146, males: n = 12, females: n = 10). Before (Pre-) and after (Post-) training, a repeated sprint ability (RSA) test was performed (10-s cycle sprints with 20-s recovery between sprints, until exhaustion), and aerobic and anaerobic qualities were evaluated in normoxia. RESULTS: The number of sprints during RSA increased after training in HYP from 11 to 21 in males and from 8 to 14 in females ( P < 0.001, 95% confidence interval = 5-11), without significant changes after RSN (10 vs 14 and 8 vs 10 in males and females, respectively). No improvements in mean or peak power output were found in either group. Total work during RSA improved after training in all groups (+9 ± 2 kJ, P < 0.001). Tissue saturation index during the repeated sprints was higher in females than males (+10% ± 2%, P…

INTRODUCTION: Maximal acceleration and deceleration tasks are frequently required in team sports, often occurring rapidly in response to external stimuli. Accelerating and decelerating can be associated with lower limb injuries; thus, knowledge of joint mechanics during these tasks can improve the understanding of both human high performance and injury mechanisms. The current study investigated the fundamental differences in lower limb joint mechanics when accelerating and decelerating by directly comparing the hip, knee, and ankle joint moments and work done between the two tasks. METHODS: Twenty participants performed maximal effort acceleration and deceleration trials, with three-dimensional marker trajectories and ground reaction forces collected simultaneously. Experimental data were combined with inverse dynamics analysis to compute joint moments and work. RESULTS: Net joint work for all lower limb joints was positive during acceleration and negative during deceleration. This occurred because of significantly greater positive work production from the ankle and hip during…

PURPOSE: To determine in trained females and males i) the agreement between the gas exchange threshold (GET), lactate threshold 1 (LT1), and heart rate variability threshold 1 (HRVT1), as well as between the respiratory compensation point (RCP), lactate threshold 2 (LT2), and heart rate variability threshold 2 (HRVT2), and ii) the reproducibility of HRVT1 and HRVT2 during 2-min incremental step protocols. METHODS: Fifty-seven trained participants (24 females) completed a 2-min step incremental test to task failure. Nineteen participants (eight females) completed a second test to evaluate reproducibility. Gas exchange and ventilatory responses, blood lactate concentration, and RR time series were recorded to assess the oxygen consumption (V̇O 2 ) and heart rate (HR) associated with the GET, RCP, LT1, LT2, HRVT1, and HRVT2. RESULTS: V̇O 2 -GET versus V̇O 2 -HRVT1 and HR-GET versus HR-HRVT1 were statistically different for females (29.5 ± 4.0 vs 34.6 ± 6.1 mL·kg -1 ·min -1 ; 154 ± 11 vs 166 ± 12 bpm) and for males (33.9 ± 4.2 vs 42.7 ± 4.6 mL·kg -1 ·min -1 ; 145 ± 11 vs 165 ± 9 bpm; P…

PURPOSE: The objective of this study is to investigate the effects of acute diet and exercise manipulation on resting metabolic rate (RMR) measurement variability and dual-energy x-ray absorptiometry (DXA) body composition estimates. METHODS: Ten male and 10 female endurance athletes (12 cyclists, 5 triathletes, 4 runners) of tier 2 ( n = 18) to tier 3 ( n = 2) caliber underwent five conditions using a Latin square counterbalance design. For 24 h, athletes consumed a diet providing excessive energy availability (EA) (75 kcal⋅kg fat-free mass (FFM) -1 ) without exercise (GEA rest ), high-EA (45 kcal⋅kg FFM -1 ) without (HEA rest ) or with exercise (HEA ex ), or low-EA (15 kcal⋅kg FFM -1 ) without (LEA rest ) or with exercise (LEA ex ). Exercise involved two bouts of cycling (morning bout: 149 ± 34 min at 55% of maximal aerobic capacity (V̇O 2max ); afternoon bout: 60 min at 65% of V̇O 2max ) that resulted in a cumulative exercise energy expenditure of 30 kcal⋅kg FFM -1 . The following day, RMR and DXA measurements occurred after a 10-h fast and 12-h postexercise. RESULTS: There were…

PURPOSE: Energy deficiency decreases muscle protein synthesis (MPS), possibly due to greater whole-body essential amino acid (EAA) requirements and reliance on energy stores. Whether energy deficit-induced anabolic resistance is overcome with non-nitrogenous supplemental energy or if increased energy as EAA is needed is unclear. We tested the effects of energy as EAA or carbohydrate, combined with an EAA-enriched whey protein, on postexercise MPS (%·h -1 ) and whole-body protein turnover (g protein·240 min -1 ). METHODS: Seventeen adults (mean ± SD; age: 26 ± 6 yr, body mass index: 25 ± 3 kg·m -2 ) completed a randomized, parallel study including two 5-d energy conditions (BAL; energy balance; daily energy requirements (DEF), -30% ± 3% energy requirements) separated by ≥7 d. Volunteers consumed EAA-enriched whey with added EAA (+EAA; 304 kcal, 56 g protein, 48 g EAA, 17 g carbohydrate, 2 g fat; n = 8) or added carbohydrate (+CHO; 311 kcal, 34 g protein, 24 g EAA, 40 g carbohydrate, 2 g fat; n = 9) following exercise. MPS and whole-body protein synthesis (PS), breakdown (PB), and net…

INTRODUCTION: To evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with an eumenorrheic (EUM) cycle, on maximal strength and power between hormone phases. METHODS: One-repetition maximum (1RM) leg press and bench press, peak force from knee extension and upright row isometric dynamometry, and power from vertical jump height and reactive strength index (cm·s -1 ) were measured in 60 healthy, active women (mean ± SD; age: 26.5 ± 7.0 yr, body mass index: 23.8 ± 3.0 kg·m -2 ) who were monophasic OC users for ≥6 months ( n = 21), had an H-IUD for ≥6 months ( n = 20), or had regularly naturally occurring menstrual cycle for ≥3 months or were using a nonhormonal IUD (EUM; n = 19). Participants were randomly assigned to begin in the follicular phase/placebo pill (low hormone phase (LHP)) or in the luteal phase/active pill (high hormone phase (HHP)) and were tested once in each phase. Estimates of total lean mass (LM), leg LM, and arm LM were measured via dual energy x-ray absorptiometry. Separate univariate ANCOVAs were used to assess the…

ABSTRACT: Performance in intermittent sports relies on the interplay between multiple physiological systems determining the capacity to perform short explosive efforts as well as repeated intense actions with limited recovery over the course of an entire game. Testing should reflect these demands to allow for sport- and position-specific capacity analyses that eventually may translate into optimized training and improved performance. This may include individual load management and optimized training prescription, intensity targeting for specific positions or individual athletes, as well as benchmarking for monitoring of training progression and enhanced engagement of athletes. This review provides an overview of available tests in different exercise domains identified as relevant (from assessment of single explosive actions to intermittent endurance capacity), forming the basis for recommendations on how to compose a comprehensive yet feasible test battery that may be integrated into the seasonal competition and training plan. The test procedures should cover the performance…

PURPOSE: Advanced insight in energy requirements of Paralympic athletes is imperative for optimizing their nutritional counseling. Given the lack of accurate data on total daily energy expenditure (TDEE) of Paralympic athletes, this study aimed to assess energy expenditure and nutritional intake of a large cohort of Paralympic athletes, across different sports and disabilities. METHODS: In this cross-sectional study, 48 Dutch and Norwegian Paralympic athletes (19 male/29 female) with various disabilities, competing in Para cycling, wheelchair tennis, wheelchair basketball, Para Nordic skiing, and alpine skiing participated. TDEE was assessed by the gold standard doubly labeled water method over a 14-d period, resting metabolic rate by ventilated hood indirect calorimetry, energy intake by three unannounced 24-h dietary recalls, body composition by dual-energy x-ray absorptiometry, and exercise training duration by a training log. RESULTS: Mean TDEE was 2908 ± 797 kcal·d -1 , ranging from 2322 ± 340 kcal·d -1 for wheelchair basketball players to 3607 ± 1001 kcal·d -1 for Para…