Application of Artificial Intelligence to Automate the Reconstruction of Muscle Cross-Sectional Area Obtained by Ultrasound

PURPOSE

Manual reconstruction (MR) of the vastus lateralis (VL) muscle cross-sectional area (CSA) from sequential ultrasound (US) images is accessible, is reproducible, and has concurrent validity with magnetic resonance imaging. However, this technique requires numerous controls and procedures during image acquisition and reconstruction, making it laborious and time-consuming. The aim of this study was to determine the concurrent validity of VL CSA assessments between MR and computer vision-based automated reconstruction (AR) of CSA from sequential images of the VL obtained by US.

METHODS

The images from each sequence were manually rotated to align the fascia between images and thus visualize the VL CSA. For the AR, an artificial neural network model was utilized to segment areas of interest in the image, such as skin, fascia, deep aponeurosis, and femur. This segmentation was crucial to impose necessary constraints for the main assembly phase. At this stage, an image registration application, combined with differential evolution, was employed to achieve appropriate adjustments between the images. Next, the VL CSA obtained from the MR ( n = 488) and AR ( n = 488) techniques was used to determine their concurrent validity.

RESULTS

Our findings demonstrated a low coefficient of variation (CV) (1.51%) for AR compared with MR. The Bland-Altman plot showed low bias and close limits of agreement (+1.18 cm 2 , -1.19 cm 2 ), containing more than 95% of the data points.

CONCLUSIONS

The AR technique is valid compared with MR when measuring VL CSA in a heterogeneous sample.

An umbrella review of systematic reviews on interventions of physical activity before pregnancy, during pregnancy, and postpartum to control and/or reduce weight gain

BACKGROUND

The increasing prevalence of overweight and obesity worldwide represents a (chronic) complex public health problem. This is also seen among women of childbearing age despite increased efforts to promote physical activity (PA) interventions. Excessive gestational weight gain (GWG) is associated with negative health outcomes for both mothers and offspring.

OBJECTIVES

To summarize current systematic reviews (SRs) on PA interventions during pregnancy and postpartum to prevent excessive GWG and identify the most effective approaches.

SEARCH STRATEGY

A literature search was conducted on major electronic databases (MEDLINE/Pubmed, Cochrane, Web of Science, Epistemonikos) from inception to March 2023.

SELECTION CRITERIA

This study included SRs and meta-analyses of studies involving women aged 18 years or older from diverse ethnic backgrounds, who were either in the preconception period, pregnant, or within 1 year postpartum and who had no contraindications for exercise. Women with chronic diseases, such as pre-existing diabetes (type 1 or type 2) were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data from selected studies assessing the impact of PA in preconception, pregnancy, and postpartum. Methodologic quality was assessed with the AMSTAR-2 tool. A narrative summary of results addresses relationships between PA and weight before, during, and after pregnancy, informing future research priorities for preventing excessive weight gain. This study is registered on PROSPERO (CRD420233946666).

MAIN RESULTS

Out of 892 identified articles, 25 studies were included after removing duplicates, unrelated titles, and screening titles and abstracts for eligibility. The results demonstrate that PA can help prevent excessive GWG and postpartum weight retention. Structured and supervised moderate-intensity exercise, at least twice a week, and each session lasting a minimum of 35 min seems to provide the greatest benefits.

CONCLUSIONS

Women who comply with the PA program and recommendations are more likely to achieve adequate GWG and return to their pre-pregnancy body mass index after delivery. Further research is warranted to explore how preconception PA influences pregnancy and postpartum outcomes given the absence of identified preconception-focused interventions.

Pickleball Primer: An Overview of Common Injuries, Treatment, and Optimization Strategies in Pickleball Athlete

Pickleball is one of the fastest growing sports in the United States with millions of players nationwide. It is a relatively appealing sport because of its ease of access, low impact, and highly social atmosphere, allowing players of all ages to participate. As the number of players continues its dramatic increase, player injuries are certain to increase in turn. There is little to no orthopaedic research on pickleball-related injuries and a paucity of data regarding treatment and prevention strategies. This summary was designed to familiarize orthopaedic surgeons with the basics of the sport and highlight potential pickleball-related injuries they may encounter in practice.

Optimization of Sprint Training Among European Coaches: Quality Over Quantity

PURPOSE

To describe how high-level European sprint coaches (from 100 to 400 m) work to improve important factors associated with the quality of the holistic training process and the quality of the specific training session.

METHODS

A descriptive analysis was conducted using questionnaires from 31 European elite sprint coaches (ie, training athletes defined as tiers 3, 4, and 5) who participated voluntarily.

RESULTS

The coaches used traditional periodization (45%) with a 10- to 15-day tapering phase (48%) that includes a reduction in volume, maintenance of intensity, and focus on correct technical execution. In the 3 mesophases, coaches prioritized the basic development of strength and sprint work in the first phases of the season and emphasized more sprint-specific work in the competitive phase. Before sessions, adjustments were made based on factors such as psychological (77%), technical (48%), and physical (39%) parameters. In-session load management relies on a combination of objective and subjective measures (55%), in which the dialogue with athletes (65%) was regarded as the main resource. Feedback during and after sessions covers technical (54%), psychological (48%), and physical (35%) aspects. Recovery protocols after sessions mainly involve rest and professional guidance (42%). For performance assessment and testing, coaches utilize countermovement jump (52%), force-velocity profile (45%), and 30-m flying (61%) as main tools.

CONCLUSIONS

European sprint coaches demonstrated a comprehensive approach to planning and management, shedding light on the multifaceted nature of their training methodologies and the diverse tools employed for athlete testing and monitoring.

The association of physical activity and leisure-time sedentary behavior with perceived stress among Chinese adults: A cross-sectional study based on the Chinese health and nutrition survey data

Objective

Physical activity (PA) and sedentary behavior (SB) include several domains, whether the association of PA and SB with perceived stress is domain-specific is not clear. This study aims to identify associations of physical activity (exercise and housework) and leisure-time sedentary behavior (LTSB) with perceived stress among Chinese adults.

Methods

The data were collected from the 2015 China Health and Nutrition Survey (CHNS). Respondents completed multiple questionnaires developed by the CHNS team, from which we extracted and sorted PA and LTSB data. Perceived stress was measured using the 14-item Perceived Stress Scale. PA was measured using a questionnaire covering 7 types of commonly practiced exercises and 4 types of housework activities among Chinese individuals. Consecutive questions were used to inquire about the time spent on each type of PA. The measurement of LTSB was conducted in the same manner. Data analysis involved Chi-square test and logistic regression.

Results

11,471 adults were included, with an average age of 52.3 years, and 48.3 % were male. 69.9 % (8,019) of respondents reported high perceived stress. Following adjustment for age, gender and other factors, perceived stress was lower for adults reporting medium exercise time (1-2 h) compared with excessively (≥2 h) (OR=1.314 [95 %CI 1.071, 1.612], P<0.001) and least (<1 h) (OR=1.273 [95 %CI 1.115, 1.413], P<0.001) active adults. Perceived stress was higher for adults reporting less housework time (<1 h) compared with adults spending medium (1-2 h) (OR=0.860 [0.744, 0.993], P<0.05) and long (≥2 h) (OR=0.725 [95 %CI 0.628, 0.838], P<0.001) time on housework. Low-level LTSB (<2 h) was associated with higher perceived stress than medium- (2-4 h) (OR=0.817 [0.718, 0.930], P<0.01) and high-level LTSB (≥4 h) (OR=0.668 [0.577, 0.773], P<0.001).

Conclusions

The association of PA and SB with perceived stress is domain-specific. Medium exercise time and extended housework time are associated with reduced perceived stress. Additionally, our findings suggesting that increasing the time spent on LTSB is linked to lower perceived stress levels.

Muscle-to-Bone Ratio in NCAA Division I Collegiate Football Players by Position

ABSTRACT

Dengel, DR, Studee, HR, Juckett, WT, Bosch, TA, Carbuhn, AF, Stanforth, PR, and Evanoff, NG. Muscle-to-bone ratio in NCAA Division I collegiate football players by position. J Strength Cond Res 38(9): 1607-1612, 2024-The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB (18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA.

A Comprehensive Analysis of 10-Yard Sprint Reliability in Male and Female Youth Athletes

ABSTRACT

Wannouch, YJ, Leahey, SR, Whitworth-Turner, CM, Oliver, JL, YH, KC, Laffer, JC, and Leicht, AS. A comprehensive analysis of 10-yard sprint reliability in male and female youth athletes. J Strength Cond Res 38(9): e477-e488, 2024-This study investigates the inter-week test-retest reliability of 9.14 meter (10 yard) sprint times in youth athletes. Although essential for assessing athletic ability and training efficacy, the critical and comprehensive examination of both relative and absolute reliability indices for short-distance sprints has been insufficient in youth contexts. One hundred ninety-eight youth athletes (128 males and 70 females) underwent 2 sprint attempts across 2 separate trials 24 hours apart and within 7 days of each other. The sprints were measured using dual-beam timing gates to capture split times for 0-4.57 meter (0-5 yards), 4.57-9.14 meter (5-10 yards), and 0-9.14 meter (0-10 yards). The minimal mean difference between the best sprint times across trials was 0.02 ± 0.13 seconds for males and 0.003 ± 0.14 seconds for females. No significant mean differences were found between trials for either gender (males: p = 0.0875; females: p = 0.8752), suggesting no systematic bias in sprint times. The SEM was 0.092 seconds for males and 0.099 seconds for females, with a corresponding SEMCV% of 4.6 and 4.8%. The overall coefficient of variation was 9.8% for males and 8.9% for females. Intraclass correlation coefficient values suggested that the sprint times across trials were reliable (males: 0.80; females: 0.76). The minimal detectable change was 0.25 seconds for males, 0.27 seconds for females. Cohen's d indicated trivial effects (<0.2) for males (0.154) and females (0.021). Minimal mean differences, a low SEM , and consistent ICC values demonstrate that the 0-9.14 meter sprint is a reliable assessment in youth athletes.

Effects of Different Resistance Training Frequencies on Body Composition, Muscular Strength, Muscle Quality, and Metabolic Biomarkers in Sarcopenic Older Women

ABSTRACT

Dos Santos, VR, Antunes, M, dos Santos, L, Nascimento, MA, Pina, FLC, Carneiro, NH, Trindade, MCC, Venturini, D, Barbosa, DS, and Cyrino, ES. Effects of different resistance training frequencies on body composition, muscular strength, muscle quality, and metabolic biomarkers in sarcopenic older women. J Strength Cond Res 38(9): e521-e528, 2024-Resistance training (RT) can ameliorate outcomes related to sarcopenia by promoting beneficial changes in muscular strength, skeletal muscle mass (SMM), and muscle quality. This study compared the effects of 12 weeks of RT performed 2 and 3 sessions a week on body composition, muscular strength, muscle quality, and metabolic biomarkers in sarcopenic older women. Thirty-four sarcopenic older women (>60 years) were randomly assigned to perform a whole-body RT program, either 2 (G2X, n = 18) or 3 (G3X, n = 16) sessions a week during 12 weeks (8 exercises, single set of 10-15 repetitions). Body composition, muscular strength, muscle quality, and metabolic biomarkers were assessed before and after the intervention. Both groups increased (p < 0.05) 1 repetition maximum total muscular strength (G2X = +20.4% and G3X = +21.0%), SMM (G2X = +4.0% and G3X = +7.0%), and improved muscle quality (G2X = +16.7% and G3X = +13.6%), with no differences between groups (p > 0.05). No change over time was found for IGF-1 and testosterone (p > 0.05). Our results suggest that 12 weeks of RT performed at a lower weekly frequency is as effective as a higher frequency in improving muscular strength, SMM, and muscle quality in sarcopenic older women.

Physiological Demands of Competitive Collegiate Dance

ABSTRACT

Seifert Gonzales, AM and Stenson, MC. Physiological demands of competitive collegiate dance. J Strength Cond Res 38(9): e503-e509, 2024-Competitive collegiate dance combines elements of gymnastics and acrobatics with more traditional styles, such as ballet, jazz, and modern dance. Assessing the physiological demands and identifying clear measures of intensity and duration of such dance provide a framework for planning the competitive season and developing strength and conditioning programs. This study examined the blood lactate (BL), heart rate (HR), and ratings of perceived exertion (RPE) of 14 well-trained female dancers on a competitive collegiate dance team. Subjects completed a treadmill test to determine their lactate threshold (LT) and then performed a 120-second choreographed jazz dance routine in cumulative 30-second segments, during which physiological markers were measured. All subjects exceeded their individually determined LT values by 90 seconds into the dance routine. A moderate (rs = 0.53; p < 0.001) positive correlation was observed between HR and RPE, as was a strong (rs = 0.70; p < 0.001) positive correlation between BL and RPE. Subjects worked at or above LT for much of the 120-second jazz dance routine, indicating that competitive collegiate dance is physiologically demanding and highly anaerobic. Understanding the physiological demands of competitive collegiate dance allows strength and conditioning professionals to develop, monitor, and adjust training parameters, which will aid in minimizing injury and maximizing competitive performance in collegiate dancers.

Indices of exercise induced muscle damage following low load resistance exercise with blood flow restriction in untrained males

BACKGROUND

There is conflicting evidence regarding the presence and magnitude of exercise-induced muscle damage (EIMD) following low-load resistance training with blood flow restriction (LL+BFR), which may be related to the protocol implemented or exercise volume. Therefore, the purpose of this investigation was to examine the effects of a 75 repetition (BFR-75) (1×30, 3×15) and four sets to volitional failure (BFR-4x) protocols on indices of EIMD among untrained men.

METHODS

Twelve males with no history of lower-body resistance training during the previous six months volunteered for this investigation. One leg was randomly assigned to BFR-75, and the other to BFR-4x. Participants performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% of maximal strength with BFR. Indices of EIMD (limb circumference, perceived muscle soreness, pain pressure threshold [PPT], passive range of motion, and maximal strength [MVIC]) were recorded before exercise and 0, 24, 48, 72, and 96-hours post-exercise for each protocol.

RESULTS

There were no significant changes (P>0.05) in limb circumference, PPT, passive range of motion, or MVIC. For both BFR-75 and BFR-4x, perceived muscle soreness increased (P<0.001) similarly 24- (2.5±1.7 AU) and 48-hours (1.9±1.7 AU) post-exercise.

CONCLUSIONS

There was an increase in muscle soreness 24-48 hours post-exercise for both conditions, which may be due to metabolic stress, but this did not affect the force-generating capacity of the muscle (MVIC), suggesting minimal EIMD. The conflicting evidence of EIMD following LL+BFR may be related to differences in restriction time or overall exercise time.

Management of Proximal Hamstring Injuries: Non-operative and Operative Treatment

PURPOSE OF REVIEW

To evaluate the current evidence and literature on treatment options for proximal hamstring injuries.

RECENT FINDINGS

Patients with 3-tendon complete tears with greater than 2 cm of retraction have worse outcomes and higher complication rates compared to those with less severe injuries. Endoscopic and open proximal hamstring repair both have favorable patient reported outcomes at 5-year follow up. Proximal hamstring repair in patients who are male, with isolated semimembranosus injury, and have proximal hamstring free tendon rupture are more likely to have earlier return to sports. The Parisian Hamstring Avulsion Score (PHAS) is a validated patient-reported outcome measure to predict return to sports. Proximal hamstring injuries may occur in both elite and recreational athletes and may present with varying degrees of chronicity and severity. Injuries occur most commonly during forceful eccentric contraction of the hamstrings and often present with ischial tuberosity tenderness, ecchymosis, and hamstring weakness. Treatment decision-making is dictated by the tendons involved and chronicity. Many proximal hamstring injuries can be successfully treated with non-surgical measures. However, operative treatment of appropriately indicated proximal hamstring tendon injuries can result in significantly better functional outcomes and faster and more reliable return to sports compared to nonoperative treatment. Both endoscopic and open surgical repair techniques show high satisfaction levels and excellent patient-reported outcomes at short- and mid-term follow-up. Postoperative rehabilitation protocols vary across the literature and ongoing study is needed to clarify the optimal program, though emphasis on eccentric hamstring strengthening may be beneficial.

Polar Thigh and Other Medical Observations During the Longest Solo Unsupported One-Way Polar Ski Expedition in Antarctica

Antarctic expeditions are exceptional challenges for the human body, and medical issues such as nutritional deficiencies, polar anemia, cold injuries, and even death have been reported. We prospectively investigated medical issues encountered by a 33-year-old female adventurer completing the longest solo unsupported one-way polar ski expedition in Antarctica, covering 1484.53 km in 70 days and 16 h from Hercules Inlet to the Ross Ice Shelf, in temperatures estimated from -12 to -50°C and wind speeds of up to 60 mi/h. The adventurer developed a debilitating overuse musculoskeletal neck injury due to poor environmental conditions (ie, poor visibility, wind, and soft snow) while pulling a heavy sled and continuously holding the neck in a flexed position for checking directions on a mounted compass. The adventurer further developed a cold injury on the left calf (polar thigh) that gradually worsened and became ulcerated and more painful throughout the expedition. Potential risk factors included cold ambient temperatures, exposure to windy conditions, and clothing. After the expedition, this injury was treated with a skin graft. Important changes in body mass were observed (ie, reduction of body mass by 26.7% after the expedition) as well as general fatigue, muscle soreness, and sleep deterioration. This case study contributes to the body of knowledge of medical issues during Antarctic expeditions and provides the first scientific account of an adventurer with polar thigh. Further research into this condition is recommended.

Multicomponent Physical Program: Effects on Physical Fitness of Older Women of Different Age Groups

Purpose: Experimental studies investigating the outcomes of physical exercise among age-stratified groups of older women are still incipient. This study aimed to investigate the effects of a ten-month multicomponent physical program on the physical fitness of older women in three age-stratified groups (60-69 years, 70-79 years, and ≥80 years). Method: Participants (n = 141) were divided into three age groups: GR1 60-69 years (n = 45; 65.2 ± 2.3 years); GR2 70-79 years (n = 67; 72.9 ± 2.9 years), GR3 ≥80 years (n = 29; 83.5 ± 4.5 years). The participants performed the multicomponent physical program and were evaluated before and after the intervention with Senior Fitness Test. Data were analyzed using generalized estimating equations, Bonferroni test (p ≤.05) and effect size (Cohen's d). Results: For the group factor, there were significant differences in lower limb strength (p = .003), upper limb strength (p < .001), upper limb flexibility (p < .001), balance/agility (p < .001), and cardiorespiratory fitness (p < .001). For the time factor, significant differences were observed in lower limb strength (GR2, p = .014, small effect size), upper limb strength (GR1, p = .003; GR2, p < .001; GR3, p = .017; small effect sizes), lower limb flexibility (GR1, p = .025, non-significant effect size), cardiorespiratory fitness (GR1, p < .001, medium effect size; GR2, p = .002; small effect size). Conclusion: Physical fitness improved with training, but effects differed between age groups. Positive effects were observed for GR1 and GR2, whereas GR3 showed maintenance of physical fitness. Aging interferes more strongly in women aged 80 years and older and it is necessary for specific training programs for this age group.                                                      .

Greater weekly physical activity linked to left resting frontal alpha asymmetry in women: A study on gender differences in highly active young adults

Physical activity, beneficial for physical and psychological health, may facilitate affective mechanisms of positive emotion and approach-motivation. Greater resting frontal alpha asymmetry (FAA), an index of greater relative left than right frontal cortical activity, is a neural correlate of affective mechanisms possibly associated with active lifestyles. This study sought to amplify limited literature on the relationship between physical (in)activity, FAA, and gender differences. College students (n = 70) self-reported physical activity (Total PA) and sedentary activity (Total Sitting) via the International Physical Activity Questionnaire-Short Form (IPAQ-SF), followed by a resting electroencephalography session to record FAA. A Total PA × gender interaction (β = 0.462, t = 3.163, p = 0.002) identified a positive relationship between Total PA and FAA in women (β = 0.434, t = 2.221, p = 0.030) and a negative relationship for men (β = -0.338, t = -2.300, p = 0.025). Total Sitting was positively linked to FAA (β = 0.288, t = 2.228, p = 0.029; no gender effect). Results suggest affective mechanisms reflected by FAA (e.g., positive emotion, approach-motivation) are associated with physical activity for women, indicating a possible mechanism of the psychological benefits linked with physically active lifestyles. A positive relationship between sedentary behavior and greater left FAA may also reflect motivated mechanisms of behavior that aid in minimizing energy expenditure, particularly within the context of our highly active sample.

Androgenic Steroid Hormones and Endurance Exercise in Athletic Women

This study investigated the impact of intensive endurance exercise on circulating androgenic steroid hormones in women. Fifteen normally menstruating athletic women participated. They completed intensive endurance exercise (treadmill running) until volitional fatigue in their follicular phase, with blood samples collected at pre-exercise, volitional fatigue, 90 min and 24 h into recovery. The steroid hormones (total, free testosterone, dehydroepiandrosterone [DHEA], and DHEA-sulfate [DHEA-S], cortisol) were analyzed in blood sera. Non-parametric statistics were used to assess changes across exercise and recovery. At volitional fatigue, all hormones, except free testosterone, were significantly (p < 0.05) increased compared to pre-exercise levels. Most hormones remained elevated through 90 min of recovery, with DHEA, DHEA-S, and total testosterone changes being significant (p < 0.05). At 24 h of recovery, hormonal levels were reduced; specifically, DHEA, DHEA-S, and total testosterone compared to baseline (p < 0.01 to 0.06). Increases in cortisol levels at volitional fatigue and 90 min of recovery were correlated with reductions in total testosterone, DHEA, and DHEA-S observed at 24 h of recovery (rho > -0.62, p < 0.05). In conclusion, in menstruating women performing intensive endurance exercise during their follicular phase, their androgenic steroid hormones remain elevated during early recovery but are suppressed at 24 h of recovery. The latter finding indicates that establishing a resting endocrine equilibrium requires a longer recovery period than 24 h.

Age-adjusted CSF t-tau and NfL do not improve diagnostic accuracy for prodromal Alzheimer's disease

Cerebrospinal fluid total-tau (t-tau) and neurofilament light chain (NfL) are biomarkers of neurodegeneration and are increased in Alzheimer's disease (AD). In order to adjust for age-related increases in t-tau and NfL, cross-sectional age-adjusted norms were developed based on amyloid negative cognitively normal (CN) adults aged 41-78 years (CN, n = 137). The age-adjusted norms for t-tau and NfL did not improve receiver operating curve based diagnostic accuracies in individuals with mild cognitive impairment (MCI) due to AD (AD-MCI, n = 144). Furthermore, while NfL was correlated with higher age in AD-MCI, no significant correlation was found for t-tau. The cox proportional hazard models, applied in 429 participants with baseline t-tau and NfL, showed higher hazard ratio of progression to MCI or dementia without age-adjustments (HR = 3.39 for t-tau and HR = 3.17 for NfL), as compared to using our norms (HR = 2.29 for t-tau and HR = 1.89 for NfL). Our results indicate that utilizing normative reference data could obscure significant age-related increases in these markers associated with neurodegeneration and AD leading to a potential loss of overall diagnostic accuracy.

Meniscus Injuries in Soccer

Soccer is considered the most popular sport in the world. The game involves frequent agile maneuvers, such as rapid accelerations/decelerations and pivoting, and carries an inherent risk of high-speed collisions, which can lead to lower extremity injury. Knee and meniscus injuries can cause significant pain and disability, precluding participation in the sport. Understanding the diagnosis and management of meniscal injuries in soccer players is essential to the care of these athletes. This paper reviews meniscal anatomy, biomechanics, and mechanisms of injury; discusses the work-up, diagnosis, and management of meniscus injuries; and reports on rehabilitation, return to sport, and outcomes after meniscal injuries in soccer players.

Association between physical activity and risk of gastroesophageal reflux disease: A systematic review and meta-analysis

BACKGROUND

Lifestyle plays an important role in preventing and managing gastroesophageal reflux disease (GERD). In response to the conflicting results in previous studies, we performed a systematic review and meta-analysis to investigate this association.

METHODS

Relevant studies published until January 2023 were retrieved from 6 databases, and the prevalence of symptomatic gastroesophageal reflux (GER) or GERD was determined from the original studies. A random effects model was employed to meta-analyze the association by computing the pooled relative risk (RR) with 95% confidence intervals (95%CIs). Furthermore, subgroup and dose-response analyses were performed to explore subgroup differences and the association between cumulative physical activity (PA) time and GERD.

RESULTS

This meta-analysis included 33 studies comprising 242,850 participants. A significant negative association was observed between PA and the prevalence of symptomatic GER (RR = 0.74, 95%CI: 0.66-0.83; p < 0.01) or GERD (RR = 0.80, 95%CI: 0.76-0.84; p < 0.01), suggesting that engaging in PA might confer a protective benefit against GERD. Subgroup analyses consistently indicated the presence of this association across nearly all subgroups, particularly among the older individuals (RR<40 years:RR≥40 years = 0.85:0.69, p < 0.01) and smokers (RRsmoker:RRnon-smoker = 0.67:0.82, p = 0.03). Furthermore, a dose-response analysis revealed that individuals who engaged in 150 min of PA per week had a 72.09% lower risk of developing GERD.

CONCLUSION

Maintaining high levels of PA decreased the risk of GERD, particularly among older adults and smokers. Meeting the recommended PA level of 150 min per week may significantly decrease the prevalence of GERD.

Unraveling sex-specific risks of knee osteoarthritis before menopause: Do sex differences start early in life?

OBJECTIVE

Sufficient evidence within the past two decades have shown that osteoarthritis (OA) has a sex-specific component. However, efforts to reveal the biological causes of this disparity have emerged more gradually. In this narrative review, we discuss anatomical differences within the knee, incidence of injuries in youth sports, and metabolic factors that present early in life (childhood and early adulthood) that can contribute to a higher risk of OA in females.

DESIGN

We compiled clinical data from multiple tissues within the knee joint-since OA is a whole joint disorder-aiming to reveal relevant factors behind the sex differences from different perspectives.

RESULTS

The data gathered in this review indicate that sex differences in articular cartilage, meniscus, and anterior cruciate ligament are detected as early as childhood and are not only explained by sex hormones. Aiming to unveil the biological causes of the uneven sex-specific risks for knee OA, we review the current knowledge of sex differences mostly in young, but also including old populations, from the perspective of (i) human anatomy in both healthy and pathological conditions, (ii) physical activity and response to injury, and (iii) metabolic signatures.

CONCLUSIONS

We propose that to close the gap in health disparities, and specifically regarding OA, we should address sex-specific anatomic, biologic, and metabolic factors at early stages in life, as a way to prevent the higher severity and incidence of OA in women later in life.

An Exploration of Low Back Beliefs of Male Pre-Professional and Professional Dancers

BACKGROUND

Globally, male dancers are affected by low back pain (LBP) up to 2.5 times more than female dancers. While female dancers' beliefs around LBP and dance-specific low back movements exist, no research has explored male dancers' beliefs. This study aimed to (1) examine the low back beliefs of Australian male professional and pre-professional dancers, and (2) determine if beliefs toward common low back movements and lifting differed when current LBP or history of disabling LBP (DLBP) were considered.

METHODS

40 male dancers (mean age [SD] 26.9 years [7.9]) from a range of dance backgrounds (all participating in ballet) were recruited to complete a cross-sectional survey comprising a beliefs questionnaire considering dance-specific movement and lifting tasks, the Back Pain Attitudes Questionnaire (Back-PAQ) and the Athletic Fear Avoidance Questionnaire (AFAQ). Primary analysis included initial descriptives, a repeated measures ANOVA for movement-specific beliefs and visual thematic analysis for written responses within the belief's questionnaire. Secondary subgroup analysis included independent T-tests for those with/without current LBP and those with/without a history of DLBP.

RESULTS

Fourteen dancers reported current LBP and 30 reported a history of DLBP. Dancers held generally negative beliefs toward the low back (Back-PAQ mean 123.1 ± 9.7) with neither subgroup demonstrating significant between-group difference (P < .05). Dance-specific flexion movements were seen as safer than extension movements (P < .05), and more extended-spine lifting was seen as safer than more flexed-spine lifting (P < .05). Dancers experiencing current LBP held less positive beliefs surrounding some dance-specific movements.

CONCLUSIONS

Dancers hold negative general beliefs toward the low back irrespective of current or historical DLBP, however their beliefs surrounding dance-specific movements were relatively positive. Dancers' beliefs surrounding some movements were affected by the presence of current LBP, in particular an arabesque and a fish dive.

Unintended consequences - A qualitative exploration of baseline testing in community rugby concussion management

OBJECTIVES

Understanding key stakeholders' perceptions around the value of baseline testing, as well as barriers or facilitators experienced as part of the process, may assist with the decision-making process of whether to implement baseline testing in community sport. This study explored coaches', players' and physiotherapists' perceptions of the perceived value, barriers and facilitators of baseline testing as part of New Zealand Rugby's (NZR) community concussion initiative.

DESIGN

The study employed a pragmatic, qualitative descriptive design.

METHODS

Semi-structured interviews were used to explore participants' perceptions. In total, 73 individual interviews were conducted. The sample consisted of 36 players, 13 coaches and 24 physiotherapists involved in NZR's concussion management pathway. Interviews were audio-recorded and transcribed verbatim. Data were analysed using thematic analysis.

RESULTS

In terms of perceived value, baseline testing was reported to play a role in i) facilitating a positive concussion culture; ii) positive perceptions of rugby and player safety and iii) enhancing concussion management as part of the pathway. Barriers and facilitators of the baseline testing process included i) stakeholder buy-in as critical driver of the process and ii) contextual and operational factors. Although contextual and operational challenges exist, these participants, as key stakeholders in the process, perceived the value of baseline testing to be more important than the barriers experienced.

CONCLUSIONS

The value of baseline testing extends beyond concussion assessment and management, by enhancing community concussion awareness, attitudes and player safety. The findings of this study may assist in the decision-making process around inclusion of pre-season baseline testing in community rugby.

Evidence for Simultaneous Muscle Atrophy and Hypertrophy in Response to Resistance Training in Humans

PURPOSE

Human skeletal muscle has the profound ability to hypertrophy in response to resistance training (RT). However, this has a high energy and protein cost and is presumably mainly restricted to recruited muscles. It remains largely unknown what happens with nonrecruited muscles during RT. This study investigated the volume changes of 17 recruited and 13 nonrecruited muscles during a 10-wk single-joint RT program targeting upper arm and upper leg musculature.

METHODS

Muscle volume changes were measured by manual or automatic 3D segmentation in 21 RT novices. Subjects ate ad libitum during the study and energy and protein intake were assessed by self-reported diaries.

RESULTS

Posttraining, all recruited muscles increased in volume (range: +2.2% to +17.7%, P < 0.05), whereas the nonrecruited adductor magnus (mean: -1.5% ± 3.1%, P = 0.038) and soleus (-2.4% ± 2.3%, P = 0.0004) decreased in volume. Net muscle growth ( r = 0.453, P = 0.045) and changes in adductor magnus volume ( r = 0.450, P = 0.047) were positively associated with protein intake. Changes in total nonrecruited muscle volume ( r = 0.469, P = 0.037), adductor magnus ( r = 0.640, P = 0.002), adductor longus ( r = 0.465, P = 0.039), and soleus muscle volume ( r = 0.481, P = 0.032) were positively related to energy intake. When subjects were divided into a HIGH or LOW energy intake group, overall nonrecruited muscle volume (-1.7% ± 2.0%), adductor longus (-5.6% ± 3.7%), adductor magnus (-2.8% ± 2.4%), and soleus volume (-3.7% ± 1.8%) decreased significantly ( P < 0.05) in the LOW but not the HIGH group.

CONCLUSIONS

To our knowledge, this is the first study documenting that some nonrecruited muscles significantly atrophy during a period of RT. Our data therefore suggest muscle mass reallocation, that is, that hypertrophy in recruited muscles takes place at the expense of atrophy in nonrecruited muscles, especially when energy and protein availability are limited.

Benefits of Individualized Training in Fatigued Patients with Multiple Sclerosis

INTRODUCTION

Chronic fatigue is the most common and debilitating symptom in people with multiple sclerosis (PwMS). Recently, exercise has been proven to alleviate chronic fatigue and improve physical functions. Tailoring the training intervention to the potential fatigue causes could optimize the beneficial effects of training on fatigue. The objective of this study was to compare the effectiveness of an individualized (IND) versus a traditional (TRAD) exercise intervention in reducing chronic fatigue.

METHODS

Twenty-nine PwMS with high chronic fatigue were randomly assigned to 12 wk of either a TRAD or IND exercise intervention. TRAD comprised aerobic and resistance exercises according to the guidelines for PwMS. IND specifically addressed identified individual weaknesses. Participants visited the laboratory before and after training for the following assessments: patient-reported outcomes (fatigue, quality of life, depression questionnaires), incremental cycling test (peak oxygen uptake (V̇O 2peak )), and cycling fatigue test (maximal voluntary contraction, rating of perceived exertion).

RESULTS

Similar improvements in fatigue, depression, and quality of life were observed between groups ( P > 0.05). Compared with TRAD, IND induced a significant greater increase in V̇O 2peak (+21.0% ± 13.9% vs 6.8% ± 11.5%, P < 0.05) and a greater reduction in rating of perceived exertion at a given submaximal intensity (-30.3% ± 18.9% vs -12.1% ± 20.4%, P < 0.001), whereas maximal voluntary contraction increased similarly in both groups ( P > 0.05).

CONCLUSIONS

Although tailored exercise improved similarly fatigue and other subjective parameters (depression, quality of life, sleep quality) compared with than traditional exercise intervention, prescribing an individualized intervention led to greater improvement in V̇O 2peak (but not maximal strength) and perception of effort. This may have positive functional consequences for patients.

Can We Just Play? Internal Validity of Assessing Physiological State With a Semistandardized Kicking Drill in Professional Australian Football

PURPOSE

To examine associations between exercise heart rate (HRex) during a continuous-fixed submaximal fitness test (CF-SMFT) and an intermittent-variable protocol (semistandardized kicking drill [SSD]) in Australian Football athletes, controlling for external intensities, within-session scheduling, and environmental conditions.

METHODS

Forty-four professional male Australian Football athletes (22.8 [8.0] y) were monitored over 10 sessions involving a 3-minute CF-SMFT (12 km·h-1) as the first activity and a SSD administered 35.7 (8.0) minutes after the CF-SMFT. Initial heart rate and HRex were collected, with external intensities measured as average velocity (in meters per minute) and average acceleration-deceleration (in meters per second squared). Environmental conditions were sampled. A penalized hierarchical linear mixed model was tuned for a Bayesian information criterion minima using a 10-fold cross-validation, with out-of-sample prediction accuracy assessed via root-mean-squared error.

RESULTS

SSD average acceleration-deceleration, initial heart rate, temperature, and ground hardness were significant moderators in the tuned model. When model covariates were held constant, a 1%-point change in SSD HRex associated with a 0.4%-point change in CF-SMFT HRex (95% CI, 0.3-0.5). The tuned model predicted CF-SMFT HRex with an average root-mean-squared error of 2.64 (0.57) over the 10-fold cross-validation, with 74% and 86% of out-of-sample predictions falling within 2.7%-points and 3.7%-points, respectively, from observed values, representing the lower and upper limits for detecting meaningful changes in HRex according to the documented typical error.

CONCLUSIONS

Our findings support the use of an SSD to monitor physiological state in Australian Football athletes, despite varied scheduling within session. Model predictions of CF-SMFT HRex from SSD HRex closely aligned with observed values, considering measurement imprecision.

The effects of different levels of sports activity on health-related quality of life and lifestyle habits in high school Italian students

Physical activity (PA) is an important predictor of physical and mental health preventing chronic degenerative diseases. The purpose of this study was to investigate in a group of Italian high school students whether health-related quality of life (HRQoL) and lifestyle habits (diet) are associated with the level of physical activity performed (low, moderate, high). Data were collected from 2819 adolescents (n = 951 males). HRQoL was analyzed using the Italian version of the KIDSCREEN-52. Physical activity level was analyzed using the PAQ-A, while eating habits with KIDMED. Practicing physical activity in general improves HRQoL. Specifically, adolescents practicing moderate or high PA, in single dimensions of HRQoL, showed better mood (p < 0.001), self-perception (p < 0.001), family relationships (p < 0.001), reported a higher perception of socioeconomic status (p < 0.05), relationship with peers (p < 0.001), and social acceptance (p < 0.001). High PA subjects reported increased physical (p < 0.001) and mental health (p < 0.001), increased autonomy (p < 0.001), and school learning (p < 0.001). For lifestyle habits, practicing moderate PA showed higher adherence tox the Mediterranean diet (p < 0.001). Conclusion: Our results highlighted a positive association between the frequency of PA levels, some dimensions of HRQoL, and risk behaviors. These findings demonstrated the protective role of sports not only as a preventive strategy for the onset of chronic degenerative diseases, but also as an educator of healthy lifestyle habits, thus suggesting the importance and need to implement strategies to promote sports practice.

Test-Retest Reliability and Usefulness of a Foot-Ankle Rebound-Jump Test for Measuring Foot-Ankle Reactive Strength in Athletes

PURPOSE

This study investigated the test-retest reliability and usefulness of the foot-ankle rebound-jump test (FARJT) for measuring foot-ankle reactive strength metrics in athletes.

METHODS

Thirty-six highly trained, healthy athletes (5 female; 21.5 [3.9] y; 1.80 [0.10] m; 72.7 [10.4] kg) performed 8 repeated bilateral vertical foot-ankle rebound jumps on 2 testing days. Testing days were 1 week apart, and these sessions were preceded by a familiarization session. Reactive strength metrics were calculated by dividing jump height (in meters) by contact time (in seconds) for the reactive strength index (RSI) and flight time (in seconds) by contact time (in seconds) for the reactive strength ratio (RSR). The mean of 4 jumps (excluding the first and last 2 jumps) on each testing session were considered for RSI and RSR reliability and usefulness analysis.

RESULTS

We found a high reliability of the FARJT for RSI (intraclass correlation coefficient [ICC] > .90 and coefficient of variation [CV] = 12%) and RSR (ICC ≥ .90 and CV = 8%). Regarding their usefulness, both RSI and RSR were rated as "marginal" in detecting the smallest worthwhile change (typical error > smallest worthwhile change) and "good" in detecting a moderate change in performance.

CONCLUSIONS

The results showed that a FARJT is a highly reliable test for measuring foot-ankle reactive strength in athletes and useful for quantifying changes, for example, following a training block. However, its usefulness as an accurate daily or weekly monitoring tool in practice is questionable.

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers

Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.

Associations of body mass index, waist circumference and the weight-adjusted waist index with daily living ability impairment in older Chinese people: A cross-sectional study of the Chinese Longitudinal Healthy Longevity Survey

AIM

To investigate the associations of body mass index (BMI), waist circumference (WC) and the weight-adjusted waist index (WWI) with the impairment of activities of daily living (ADL) in older Chinese people.

METHODS

A total of 13 260 participants aged 65 years and older from the 2018 Chinese Longitudinal Healthy Longevity Survey were included in this cross-sectional study. BMI, WC and the WWI were calculated from measurements of height, weight and WC. Binary logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). Non-linear correlations were investigated using restricted cubic spline curves.

RESULTS

In multivariate logistic regression fully adjusted for confounding variables, our analyses revealed significant associations between WC and WWI and ADL impairment, with adjusted ORs (95% CI) of 1.01 (1.00, 1.01) and 1.08 (1.03, 1.12), respectively. Meanwhile, participants with a high WWI had a higher risk of ADL impairment compared with those with a low WWI, with an adjusted OR (95% CI) of 1.12 (1.02, 1.23). Subgroup analyses showed that only the association between WWI and ADL impairment did not differ in any of the different populations. In addition, we found that BMI, WC and WWI were non-linearly associated with ADL impairment.

CONCLUSIONS

There are significant associations between WC and WWI and ADL impairment in older Chinese people. The findings show the ability of the WWI to serve as a comprehensive and effective indicator of obesity in older Chinese people and emphasize the importance of assessing WWI in screening and preventing ADL impairment in older people.

Evaluation of Patient-Centric Sample Collection Technologies for Pharmacokinetic Assessment of Large and Small Molecules

Low-volume sampling devices offer the promise of lower discomfort and greater convenience for patients, potentially reducing patient burden and enabling decentralized clinical trials. In this study, we determined whether low-volume sampling devices produce pharmacokinetic (PK) data comparable to conventional venipuncture for a diverse set of monoclonal antibodies (mAbs) and small molecules. We adopted an open-label, non-randomized, parallel-group, single-site study design, with four cohorts of 10 healthy subjects per arm. The study drugs, doses, and routes of administration included: crenezumab (15 mg/kg, intravenous infusion), etrolizumab (210 mg, subcutaneous), GDC-X (oral), and hydroxychloroquine (HCQ, 200 mg, oral). Samples were collected after administration of a single dose of each drug using conventional venipuncture and three low-volume capillary devices: TassoOne Plus for liquid blood, Tasso-M20 for dry blood, both applied to the arm, and Neoteryx Mitra® for dry blood obtained from fingertips. Serum/plasma concentrations from venipuncture and TassoOne Plus samples overlapped and PK parameters were comparable for all drugs, except HCQ. After applying a baseline hematocrit value, the dry blood concentrations and PK parameters for the two monoclonal antibodies were comparable to those obtained from venipuncture. For the two small molecules, two bridging strategies were evaluated for converting dry blood concentrations to equivalent plasma concentrations. A baseline hematocrit correction and/or linear regression-based correction was effective for GDC-X, but not for HCQ. Additionally, the study evaluated the bioanalytical data quality and comparability from the various collection methods, as well as patient preference for the devices.

Classification of Force-Time Metrics Into Lower-Body Strength Domains

ABSTRACT

Geneau, MC, Carey, DL, Gastin, PB, Robertson, S, and James, LP. Classification of force-time metrics into lower-body strength domains. J Strength Cond Res 38(9): 1561-1567, 2024-The purpose of this study was to classify force-time metrics into distinct lower-body strength domains using a systematic data reduction analysis. A cross-sectional design was used, whereby competitive field sport athletes ( F = 39, M = 96) completed a series of drop jumps, squat jumps, countermovement jumps (CMJs), loaded CMJs, and 2 isometric tasks on portable force platforms, resulting in a total of 285 force-time performance metrics. The metrics were split into 4 test "families" and each was entered into a sparse principal component analysis (sPCA) model. A single metric from each component of each family-specific sPCA were selected based on the loading, reliability, and simplicity of the metric and entered into a second sPCA that included metrics across all tests. The final sPCA revealed 7 principal components each containing 2 metrics and explained a total of 53% variance of the dataset. The final principal components were interpreted as 7 lower-body strength domains: (a) dynamic force, (b) dynamic timing, (c) early isometric, (d) maximal isometric, (e) countermovement velocity, (f) reactive output, and (g) reactive timing. The findings demonstrate that a total of 7 metrics from a drop jump, CMJ, and isometric test can be used to represent ∼50% of variance in lower-body strength performance of field sport athletes. These results can help guide and simplify the lower-body strength diagnosis process in field sport athletes.

Workloads in Collegiate Women's Lacrosse Athletes During a Division II National Championship Season

ABSTRACT

Sutton, PJ, Mumford, PW, and Sunderland, KL. Workloads in collegiate women's lacrosse athletes during a Division II national championship season. J Strength Cond Res 38(9): 1651-1657, 2024-A comprehensive examination of the external and internal workloads in collegiate women's lacrosse athletes has yet to be reported. Thus, the primary purpose of this study was to determine the absolute and relative external and internal training and game workloads of National Collegiate Athletic Association (NCAA) Division II women's lacrosse athletes throughout an entire season. Data from 19 Division II women's lacrosse athletes were analyzed, encompassing each training session and game across an entire competitive season (February-May). External workloads were assessed using a wearable global positioning system, whereas internal workloads were determined through heart rate (HR) variables and session rating of perceived exertion. Game days were associated with significantly ( p < 0.05) greater absolute external and internal workloads. However, when comparing workloads relative to session duration, relative workloads between training and games were no longer significant ( p > 0.05) for total distance, high-speed running (≥15 km·h -1 ), HR-derived training impulse, or caloric expenditure. Nonetheless, relative sprint distance (>19 km·h -1 ) was significantly lower during games, whereas high-intensity accelerations (>2 m·s -2 ) and decelerations (<-2 m·s -2 ) were significantly greater during training compared with games ( p < 0.05). Practical applications of these findings suggest that coaches can better prepare athletes for game day conditions by adjusting training plans to replicate the duration and intensity of games. Overall, this comprehensive examination of internal and external workloads provides valuable data for coaches and practitioners to support performance comparisons, rehabilitation protocols, and workload analyses in collegiate women's lacrosse athletes.

Longitudinal Characterization of Pain Interference and Influential Factors in Former National Football League (NFL) Players Over a 19-Year Period: An NFL-LONG Study

Previous studies on pain experiences in retired contract sport athletes have been cross-sectional, leaving gaps in our understanding of the evolution of pain interference (PI) and factors that influence trajectories decades after sport discontinuation. This study investigated the longitudinal course of PI in former male National Football League (NFL) players over a 19-year period following sport discontinuation and examined factors influencing overall levels and trajectories of PI. Former NFL players completed health surveys in 2001, 2010, and 2019, with PI ratings measured using the 36-Item Short Form Health Survey (2001 and 2010) and the Patient-Reported Outcomes Measurement Information System (2019). Unconditional latent growth curve models analyzed overall PI severity and trajectories. Conditional latent growth curve models explored the influence of musculoskeletal injuries, osteoarthritis (OA), and depression diagnosis on PI. Over 19 years (N = 338; mean age = 48.96 ± 9.35), PI significantly increased (slope = .179, P < .001; mean Patient-Reported Outcomes Measurement Information System PI t-scores 2001 = 54.19, 2010 = 54.64, 2019 = 57.38). Cumulative musculoskeletal injuries (B = .092, P < .001) and baseline depression diagnosis (B = 4.463, P < .001) were associated with overall PI levels but not change over time. OA was significantly associated with overall PI levels (B = 6.536, P < .001) and trajectory (B = -.253, P < .001); those endorsing OA in 2001 had lower PI increases over 19 years. The body region of injury and level of play during injuries mirrored overall injury effects. PI mildly increased over 19 years, with multiple factors independently influencing overall PI levels. Enhancing former contact sport athletes' daily functionality may be achieved through holistic biopsychosocial interventions addressing musculoskeletal injuries, OA, and depression. Future research should identify factors influencing elevated trajectories of long-term PI post-sport discontinuation. PERSPECTIVE: This study assessed PI in former NFL athletes over 2 decades, revealing notable interindividual variability in trajectories over time. Musculoskeletal injuries, depression, and OA correlated with overall PI. Prevention and intervention in these 3 areas present the potential to improve disruptions in daily living due to pain in former athletes.

Identification of footstrike pattern using accelerometry and machine learning

Recent reports have suggested that there may be a relationship between footstrike pattern and overuse injury incidence and type. With the recent increase in wearable sensors, it is important to identify paradigms where the footstrike pattern can be detected in real-time from minimal data. Machine learning was used to classify tibial acceleration data into three distinct footstrike patterns: rearfoot, midfoot, or forefoot. Tibial accelerometry data were collected during treadmill running from 58 participants who each ran with rearfoot, midfoot, and forefoot strike patterns. These data were used as inputs into an artificial neural network classifier. Models were created by using three distinct acceleration data sets, using the first 100%, 75%, and 40% of stance phase. All models were able to predict the footstrike pattern with up to 89.9% average accuracy. The highest error was associated with the identification of the midfoot versus forefoot strike pattern. This technique required no pre-selection of features or filtering of the data and may be easily incorporated into a wearable device to aid with real-time footstrike pattern detection.

Return to running criteria after anterior cruciate ligament reconstruction: an online survey of 1404 Italian physiotherapists

BACKGROUND

The aim of this study is to study the clinical decision-making practice of Italian physiotherapists in return to running (RTR) after anterior cruciate ligament (ACL) reconstruction, and the differences in decision-making in relation to physiotherapist's characteristics.

METHODS

An online survey was developed, 1404 physiotherapists were contacted by email, via chartered association, or via social media.

RESULTS

Most respondents (83%) indicated that the RTR decision should be made by a multidisciplinary team with RTR clearance around 3-4 months after surgery (47%). The most important criteria guiding the RTR decision were knee flexion range of motion (ROM) >130° (50%), complete extension ROM (95%), no pain (45%) and no effusion (68%). A Limb Symmetry Index (LSI) >70% for quadriceps (49%), hamstring (48%) and LSI >90% for posterolateral hip (45%) and triceps surae strength (42%) should be achieved for RTR. Approximately half of the participants (49%) do not consider ACL laxity tests to be used for RTR decisions. Response differences were found between sample subgroups. More experienced physiotherapists and those with post graduate training had lower thresholds to clear RTR.

CONCLUSIONS

Experienced physiotherapists who treated a higher number of patients after ACL reconstruction, who had certified specialist training and a specific interest towards ACL rehabilitation, generally reported clinical practice modalities more in line with current evidence.

Sex, training variables, history of chronic disease, and chronic injury are risk factors associated with a history of exercise-associated muscle cramping in 10,973 ultramarathon race entrants: a safer XXXVIII study

BACKGROUND

The prevalence of a history of exercise-associated muscle cramping (hEAMC) among ultramarathon runners is high. While the Comrades is one of the most popular mass community-based participation ultramarathons (90 km) globally, research on the epidemiology, clinical characteristics, and risk factors of entrants' lifetime hEAMC are scarce. This research aimed to describe the epidemiology, clinical characteristics, and risk factors of hEAMC among Comrades Marathon entrants.

METHODS

This was a retrospective, cross-sectional study in which 10973 race entrants of the 2022 Comrades Marathon participated. Entrants completed a prerace medical screening questionnaire that included questions related to the lifetime prevalence (%; 95% CI), severity, treatment and risk factors (demographics, training/racing variables, chronic disease/allergies, injury) for EAMC.

RESULTS

One thousand five hundred eighty-two entrants reported hEAMC in their lifetime (14.4%; 95% CI: 13.77-15.09). There was a significantly (P<0.01) higher prevalence of male (16.10%; 95% CI:15.34-16.90) than female (8.31%; 95% CI: 7.27-9.50) entrants with hEAMC (PR=1.94; 95% CI:1.68-2.23). The prevalence of hEAMC was highest in entrants with a: 1) 1 disease increase in composite disease score (PR=1.31; 95% CI:1.25-1.39); 2) history of collapse (PR=1.87; 95% CI 1.47-2.38); 3) past chronic musculoskeletal (MSK) injury (PR=1.71; 95% CI 1.50-1.94); and 4) MSK injury in the previous 12 months (PR=2.38;95% CI: 2.05-2.77). Training-related risk factors included an increase of 10 km weekly running distance (PR=0.97; 95% CI:0.95-0.99) and a training pace increase of 1min/ km (slower) (PR=1.07; 95% CI:1.03-1.12).

CONCLUSIONS

Future research should investigate the causal relationship between risk factors identified and hEAMC in ultramarathon runners. Findings from this study could assist in effective anticipation and adequate planning for treating EAMC encounters during community-based mass participation events.

The Effects of Cycle Ergometer Versus Treadmill Exercise Stress Testing on QTc Interval Prolongation in Patients With Long QT Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

The safest and most effective exercise stress tests (EST) modalities for long QT syndrome (LQTS) are currently unknown. The main objective was to explore the effects of EST on the corrected QT interval (QTc) in patients with LQTS, and to compare the effects of different EST modalities (cycle ergometer vs treadmill).

DATA SOURCES

Systematic searches were performed in September 2022 in accordance with the PRISMA statement through PubMed, Medline, EBM Reviews, Embase, and Web of Science.

MAIN RESULTS

A total of 1728 patients with LQTS, whether congenital or acquired, without any age restrictions (pediatric age ≤18 years and adult age >19 years), and 2437 control subjects were included in the 49 studies. The QT interval data were available for 15 studies. Our analyses showed that the QT interval prolonged in a similar manner using either a cycle ergometer or a treadmill (standardized mean difference [SMD] = 1.89 [95% CI, 1.07-2.71] vs SMD = 1.46 [95% CI, 0.78-2.14], respectively). Therefore, it seems that either modality may be used to evaluate patients with LQTS.

CONCLUSIONS

The methodology for the measurement of the QT interval was very heterogeneous between studies, which inevitably influenced the quality of the analyses. Hence, researchers should proceed with caution when exploring and interpreting data in the field of exercise and LQTS.

Higher volume resistance training enhances whole-body muscle hypertrophy in postmenopausal and older females: A secondary analysis of systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

This study explored the effects of resistance training (RT) volume on muscle hypertrophy in postmenopausal and older females.

METHODS

This systematic review searched randomized controlled trials (RCTs) on PubMed/MEDLINE, Scopus, Web of Science, and SciELO. Studies with postmenopausal (age ≥ 45 y) or older females (age ≥ 60 y) that compared RT (whole-body) effects on muscle hypertrophy with a control group (CG) were included. Independently reviewers selected the studies, extracted data, and performed the risk of bias of RCTs (RoB2) and certainty of the evidence (GRADE). Whole-body lean mass, free-fat mass, and skeletal muscle mass measurements were included as muscle hypertrophy outcomes. A random-effects model standardized mean difference (Hedges'g), and 95% confidence interval (95%CI) were used for meta-analysis.

RESULTS

Fourteen RCTs (overall RoB2: some concerns, except one study with high risk; GRADE: low evidence) were included. RT groups were divided into low (LVRT, total volume: 445.0 au) and high-volume (HVRT, total volume: 997.3 au). Most exercises performed were arm curl, bench press or chest press, calf raise, leg curl, leg extension, leg press or squat, seated row or lat pulldown, and triceps pushdown. Both groups experienced muscle hypertrophy (HVRT = ∼1.3 kg vs. LVRT = ∼0.9 kg) when compared to CG, although HVRT demonstrated moderate effects size (HVRT = 0.52, 95%CI: 0.27, 0.77) and LVRT demonstrated small effects size (LVRT = 0.34, 95%CI: 0.14, 0.53).

CONCLUSIONS

Compared to CG, results suggest that the HVRT protocol elicits superior improvements in muscle hypertrophy outcomes than LVRT in postmenopausal and older females.

Association between baseline levels of muscular strength and risk of stroke in later life: The Cooper Center Longitudinal Study

BACKGROUND

Muscular strength is an important component of physical fitness. We evaluated the relationship between baseline muscular strength and risk of stroke among adults who were aged ≥65 years during follow-up.

METHODS

We included 7627 healthy adults (mean age = 43.9 years, 86.0% male) underwent a baseline physical examination between 1980 and 1989. Muscular strength was determined by 1-repetition maximum measures for bench press and leg press and categorized into age- and sex-specific tertiles for each measure. Cardiorespiratory fitness (CRF) was assessed via a maximal treadmill exercise test. Those enrolled in fee-for-service Medicare from 1999 to 2019 were included in the analyses. Associations between baseline strength and stroke outcomes were estimated using a modified Cox proportional hazards model. In a secondary analysis, we examined stroke risk by categories of CRF where Quintile 1 = low, Quintiles 2-3 = moderate, and Quintiles 4-5 = high CRF based on age and sex.

RESULTS

After 70,072 person-years of Medicare follow-up, there were 1211 earliest indications of incident stroke. In multivariable analyses, the hazard ratio (95% confidence interval (95%CI)) for stroke across bench press categories were 1.0 (referent), 0.96 (0.83-1.11), and 0.89 (0.77-1.04), respectively (p trend = 0.14). The trend across categories of leg press was also non-significant (p trend = 0.79). Adjusted hazard ratio (95%CI) for stroke across ordered CRF categories were 1.0 (referent), 0.90 (0.71-1.13), and 0.72 (0.57-0.92) (p trend < 0.01).

CONCLUSION

While meeting public health guidelines for muscular strengthening activities is likely to improve muscular strength as well as many health outcomes in older adults, performing such activities may not be helpful in preventing stroke. Conversely, meeting guidelines for aerobic activity is likely to improve CRF and lower stroke risk.

Hamstring-to-quadriceps activation ratio during lower-limb strengthening exercises

Multiple exercises included in strength training involve greater activation of the quadriceps compared to hamstring muscles, which may lead to knee joint imbalances. The aim of this study was to examine the ratio of surface electromyography (sEMG) activity hamstring and quadriceps muscle groups (hamstring-to-quadriceps activation ratio; H:Q EMG), as well as lateral to medial hamstring activation ratio (LH:MH) in parallel squat, Romanian deadlift, hip thrust, lying leg curl and seated knee extension. The H:Q EMG was greater during lying leg curl compared to other exercises during both the concentric and eccentric phase, however the Romanian deadlift and hip thrust also resulted in relatively high H:Q EMG. Pairwise comparisons revealed that LH:MH was greater in the parallel squat compared to the Romanian deadlift and hip thrust in the concentric phase, and compared to the Romanian deadlift and hip thrust during the eccentric phase. Our data suggests that the lying leg curl promotes the greatest hamstring activation and H:Q EMG, amongst the exercises investigated, while also providing relatively homogenous LH:MH. The lying leg curl should be considered as a primary exercise in rehabilitation and training programmes, aiming to proportionally activate LH:MH and increase H:Q EMG, which may improve knee muscle balance.

Patellofemoral pain and musculoskeletal features in young pre- and post-pubertal female dancers

The aim of this study was to examine associations between patellofemoral pain (PFP) and musculoskeletal features (such as tendon structure and bone properties) in young (pre- and post-pubertal) female dancers. A total of 49 dancers participated in this study (mean age 13.6 ± 2.9; weight 47.0 ± 13.2; height 153.7 ± 12.9 and body mass index (BMI) 19.4 ± 3.1) and were assessed for the following factors: dance background and Tanner stage through interviews; ultrasonography assessments of bone properties and patellar tendon structure through ultrasonographic tissue characterization and quantitative ultrasound, respectively; and anthropometric measurements, muscle strength, range of motion (ROM), hypermobility and PFP through physical examinations. PFP was found in 49% of the participants. Post-pubertal dancers with no-PFP were found to have greater muscle strength, greater radial and tibial properties, and better tendon structure compared to pre-pubertal dancers with PFP and compared to pre-pubertal dancers with no-PFP [F(2, 41) = 18.64, p < .001; F(2, 41) = 20.46, p < .001; F(2, 41) = 33.06, p < .001; and, F(2, 41) = 6.02, p = .007, respectively]. Logistic regression showed that tibial bone properties and range of movement (ROM) in hip external rotation were significantly associated with PFP [odds ratio (OR) = .889 and OR = 2.653, respectively; Cox & Snell R2 = .701]. The study revealed a high prevalence of PFP among young dancers, with low bone properties and hyperjoint ROM emerging as the main factors that are related to PFP. These findings should be addressed by medical teams, athletic trainers, and dance teachers regarding the need for implementing modifications to dance training programmes and injury-prevention strategies in young pre-pubertal dancers.

Periodontal disease and sports performance: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess the association between athletic performance and periodontal disease (PD). Observational studies published up to April 2022 were searched in online databases (PubMed, Scopus, Web of Science, The Cochrane Library, LILACS, OpenGrey, and Google Scholar). PECO statement focused on studies with professional athletes (Participants) with PD (Exposition) compared to those with healthy periodontium (Comparison) and its effects on sports performance (outcome). Searches were conducted according to the PRISMA guidelines (registration protocol: 10.17605/OSF.IO/7ADH6) and risk of bias evaluation according to the Joanna Briggs Institute checklist. A total of 793 references were retrieved, of which eight were considered eligible. Two studies did not show an association between clinical PD parameters and performance. A meta-analysis with 396 participants suggested a relationship between PD and self-reported reduction in sports performance (odds ratio [OR] = 1.55; 95% confidence interval [CI] 1.04-2.31; p = 0.03; I2 = 0%) with moderate quality of evidence accordingly GRADE analysis. Despite the differences in performance evaluations between studies, PD was associated with reduced self-reported sports performance. Additional studies assessing confounding factors and objective assessment of PD and performance are needed to clarify the real effect of both conditions.

Peripheral to brain and hippocampus crosstalk induced by exercise mediates cognitive and structural hippocampal adaptations

Endurance exercise leads to robust increases in memory and learning. Several exercise adaptations occur to mediate these improvements, including in both the hippocampus and in peripheral organs. Organ crosstalk has been becoming increasingly more present in exercise biology, and studies have shown that peripheral organs can communicate to the hippocampus and mediate hippocampal changes. Both learning and memory as well as other hippocampal functional-related changes such as neurogenesis, cell proliferation, dendrite morphology and synaptic plasticity are controlled by these exercise responsive peripheral proteins. These peripheral factors, also called exerkines, are produced by several organs including skeletal muscle, liver, adipose tissue, kidneys, adrenal glands and circulatory cells. Previous reviews have explored some of these exerkines including muscle-derived irisin and cathepsin B (CTSB), but a full picture of peripheral to hippocampus crosstalk with novel exerkines such as selenoprotein 1 (SEPP1) and platelet factor 4 (PF4), or old overlooked ones such as lactate and insulin-like growth factor 1 (IGF-1) is still missing. We provide 29 different studies of 14 different exerkines that crosstalk with the hippocampus. Thus, the purpose of this review is to explore peripheral exerkines that have shown to exert hippocampal function following exercise, demonstrating their particular effects and molecular mechanisms in which they could be inducing adaptations.

Equine allogeneic tenogenic primed mesenchymal stem cells: A clinical field study in horses suffering from naturally occurring superficial digital flexor tendon and suspensory ligament injuries

BACKGROUND

Mesenchymal stem cells are an innovative therapeutic for various equine orthopaedic diseases, including soft tissue injuries.

OBJECTIVES

To evaluate the safety and efficacy of tenogenic primed equine allogeneic peripheral blood-derived mesenchymal stem cells (tpMSCs) in horses with naturally occurring superficial digital flexor tendon (SDFT) and suspensory ligament (SL) injuries.

STUDY DESIGN

Multicentre, blinded, randomised, placebo-controlled clinical trial.

METHODS

One hundred client-owned horses with SDFT and SL injuries were randomised to receive an intralesional tpMSC (66) or saline (34) injection. Clinical and ultrasonographic evaluation was performed before treatment and on Days 56 ± 3 and 112 ± 3 after treatment. Long-term data on re-injury was collected up to 2 years after treatment.

RESULTS

Significantly more tpMSC-treated horses achieved improvement in fibre alignment score (FAS) (100% vs. 54.5%, p < 0.001) and echogenicity (97.0% vs. 57.6%, p < 0.001) on Day 112 ± 3, and their lesion size decreased significantly (-27.6 ± 25.91 vs. -4.6 ± 26.64 mm2, p < 0.001) compared to the placebo group. A FAS = 0 was achieved in 65% of tpMSC-treated horses, as compared to 9% of placebo-treated horses at Day 112 ± 3. The attending veterinarians reported no re-injury in 41 of 53 tpMSC and in 2 of 26 saline-treated horses available for long-term follow-up (p < 0.001).

MAIN LIMITATIONS

As this study consisted of client-owned horses, no samples for histology were collected. Long-term follow-up was only available for a subset of enrolled horses.

CONCLUSIONS

The intralesional administration of tpMSCs was safe and improved the quality of healing and long-term outcomes in sports horses with naturally occurring SDFT and suspensory injuries.

Test-Retest Reliability of Running Economy and Metabolic and Cardiorespiratory Parameters During a Multistage Incremental Treadmill Test in Male Middle- and Long-Distance Runners

This study investigated the test-retest reliability of running economy (RE) and metabolic and cardiorespiratory parameters related to endurance running performance using a multistage incremental treadmill test. On two occasions separated by 21-28 days, 12 male middle- and long-distance runners ran at 10, 11, 12, 13, and 14 km/hr for 8 min each stage, immediately followed by a ramp test to volitional exhaustion. Carbohydrate (10% maltodextrin solution) was consumed before and during the test to provide ∼1 g/min of exercise. RE, minute ventilation (V˙E), oxygen consumption (V˙O2), carbon dioxide production (V˙CO2), respiratory exchange ratio (RER), heart rate (HR), ratings of perceived exertion (RPE), and blood glucose and lactate concentrations were recorded for each stage and at volitional exhaustion. Time-to-exhaustion (TTE) and peak oxygen consumption (V˙O2peak) during the ramp test were also recorded. Absolute reliability, calculated as the coefficient of variation (CV) between repeated measures, ranged from 2.3% to 3.1% for RE, whereas relative reliability, calculated as the intraclass correlation coefficient (ICC), ranged from .42 to .79. V˙E, V˙O2, V˙O2peak, V˙CO2, RER, and HR had a CV of 1.1%-4.3% across all stages. TTE and RPE had a CV of 7.2% and 2.3%-10.8%, respectively, while glucose and lactate had a CV of 4.0%-17.8%. All other parameters, except for blood glucose, were demonstrated to have good-to-excellent relative reliability assessed by ICC. Measures of RE, V˙O2peak, and TTE were reliable during this two-phase multistage incremental treadmill test in a cohort of trained and highly trained male middle- and long-distance runners.

Optical Marker-Based Motion Capture of the Human Spine: A Scoping Review of Study Design and Outcomes

Biomechanical analysis of the human spine is crucial to understanding injury patterns. Motion capture technology has gained attention due to its non-invasive nature. Nevertheless, traditional motion capture studies consider the spine a single rigid segment, although its alignment changes during movement. Moreover, guidelines that indicate where markers should be placed for a specific exercise do not exist. This study aims to review the methods used to assess spine biomechanics using motion capture systems to determine the marker sets used, the protocols used, the resulting parameters, the analysed activities, and the characteristics of the studied populations. PRISMA guidelines were used to perform a Scoping Review using SCOPUS and Web of Science databases. Fifty-six journal and conference articles from 1997 to 2023 were considered for the analysis. This review showed that Plug-in-Gait is the most used marker set. The lumbar spine is the segment that generates the most interest because of its high mobility and function as a weight supporter. Furthermore, angular position and velocity are the most common outcomes when studying the spine. Walking, standing, and range of movement were the most studied activities compared to sports and work-related activities. Male and female participants were recruited similarly across all included articles. This review presents the motion capture techniques and measurement outcomes of biomechanical studies of the human spine, to help standardize the field. This work also discusses trends in marker sets, study outcomes, studied segments and segmentation approaches.

Zapping the brain to enhance sport performance? An umbrella review of the effect of transcranial direct current stimulation on physical performance

Concepts such as "neurodoping" have contributed to an expansion in the area of transcranial direct current stimulation (tDCS) and its impact over physical performance in recent years. This umbrella review examines meta-analyses to evaluate tDCS's impact on exercise performance in healthy individuals. We identified 9 meta-analyses that met our inclusion criteria, encompassing 50 crossover studies and 683 participants. Like previous meta-analyses, we found a small but significant effect across individual studies (gz = 0.28, 95%CI [0.18, 0.39]). However, we also found clear evidence of publication bias, low power and substantial variability in methodological decisions. The average effect became non-significant after accounting for publication bias (grm = 0.10, 95%CrI [-0.04, 0.20], BF10 = 0.99), and a specification curve analysis showed that the final effect could range from g = -0.23 to g = 0.33, depending on decisions such as the formula used for estimating the effect size and multiple additional analytic steps. Overall, our findings suggest that current evidence does not conclusively support acute tDCS as an exercise performance enhancer.

Describing the Flick Movement Kinematic Biomechanically and Investigating the Effect of Thrower's Ten Exercises in Underwater Hockey Players

CONTEXT

Analyzing flick movement kinematics biomechanically is important to prevent sport-related injuries in underwater hockey players since the aquatic-based flick movement is completely different from land-based flick movements. The study aimed to describe the flick movement kinematic biomechanically in underwater hockey players. Moreover, this study further aimed to investigate the effect of the Thrower's Ten exercises on flick movement kinematics in underwater hockey players.

DESIGN

Descriptive laboratory study.

METHODS

Seventeen underwater hockey players (age: 26.2 [4.3] y; sports age: 6.2 [4.5] y) were included. First, 2 underwater cameras using motion capture video analysis MATLAB were used to biomechanically analyze the angular changes on the shoulder, elbow, wrist, and body while players were performing the flick movements. Players were then recruited to the Thrower's Ten exercise program for 6 weeks. Flick movement kinematics and flick-throwing distance were recorded at baseline and 6 weeks.

RESULTS

The flick movement kinematic patterns demonstrated increased shoulder flexion (from 102.5° to 144.9°), wrist extension (from 9.5° to 10.8°), and upper-extremity rotation (from 5.7° to 56.8°) while decreased elbow extension (from 107.7° to 159.2°) from the stick met the puck until the competition of the movement. The Thrower's Ten exercises improved the elbow extension (P = .04), wrist extension (P = .01), body rotation (P < .001), and flick-throwing distance (P < .001) from baseline to 6 weeks.

CONCLUSION

This study describes the underwater flick kinematic technique biomechanically and interprets preliminary findings for the first time. Thus, 6 weeks of Thrower's Ten exercise program provides more body muscle movements than the smaller ones during the flick movements and higher flick-throwing distance in underwater hockey players.

Seasonal Muscular Power Changes: Considerations of Concurrent Resistance and Field-Based Training in Professional Rugby League

ABSTRACT

Redman, KJ, Wade, L, Whitley, R, Connick, MJ, Kelly, VG, and Beckman, EM. Seasonal muscular power changes: considerations of concurrent resistance and field-based training in professional rugby league. J Strength Cond Res 38(9): 1620-1626, 2024-A rugby league player's ability to develop or maintain lower-body power will be significantly influenced by the resistance and field-based training loads completed. This study aimed to examine the power changes across a rugby league season and to investigate the relationship of concurrent training and training experience on power changes. Eighteen rugby league players participated in this study. Lower-body power was evaluated using a countermovement jump throughout the season. Four measures of external training loads were collected. A Friedman's test was used to assess differences in power throughout different phases of the season. A series of Spearman's rank-order correlations were conducted to assess the relationship between percentage changes in power during the training block, external training loads, and training experience. Countermovement jump peak velocity significantly decreased from the start ( p = 0.006) and end of pre-season ( p = 0.022) to the late competition. Correlation analysis revealed a large significant association between early competition field-based external loads (relative ( rs = -0.571) and total distance ( rs = -0.628)) and change in peak power. Very large significant negative relationships were also observed between mid-competition volume load with change in peak force ( rs = -0.825) and peak power ( rs = -0.736). Training experience was not significantly associated with changes in muscular power variables throughout this study. Coaches should seek to monitor changes in peak power when competition begins and to assist with decision-making for potential adjustments to running volume and intensity during field-based sessions.

Measuring Vertical Jump Height With Artificial Intelligence Through a Cell Phone: A Validity and Reliability Report

ABSTRACT

Erik, HT, Onn, SW, and Montalvo, S. Vertical jump height with artificial intelligence through a cell phone: a validity and reliability report. J Strength Cond Res 38(9): e529-e533, 2024-This study estimated the reliability and validity of an artificial intelligence (AI)-driven model in the My Jump 2 (My Jump Lab ) for estimating vertical jump height compared with the Force Platform (FP). The cross-sectional study involved 88 athletes (33 female and 55 male athletes), performing a total of 264 countermovement jumps with hands on hips. "Jump heights were simultaneously measured using the FP and the My Jump 2 app." The FP estimated jump heights using the impulse-momentum method, whereas My Jump 2 used the flight-time method, with the latter using an AI feature for automated detection of jump take-off and landing. Results indicated high reliability for the AI model (intraclass correlation coefficient [ICC 1,3 ] = 0.980, coefficient of variation [CV] = 4.12) and FP (ICC 1,3 = 0.990, CV = 2.92). Validity assessment showed strong agreement between the AI model and FP (ICC 2,k = 0.973). This was also supported by the Bland-Altman analysis, and the ordinary least products regression revealed no significant systematic or proportional bias. The AI-driven model in My Jump 2 is highly reliable and valid for estimating jump height. Strength and conditioning professionals may use the AI-based mobile app for accurate jump height measurements, offering a practical and efficient alternative to traditional methods.

Fatigue Alleviation by Low-Level Laser Preexposure in Ischemic Neuromuscular Electrical Stimulation

PURPOSE

Despite its susceptibility to muscle fatigue, combined neuromuscular electrical stimulation (NMES) and blood flow restriction (BFR) are effective regimens for managing muscle atrophy when traditional resistance exercises are not feasible. This study investigated the potential of low-level laser therapy (LLLT) in reducing muscle fatigue after the application of combined NMES and BFR.

METHODS

Thirty-six healthy adults were divided into control and LLLT groups. The LLLT group received 60 J of 850-nm wavelength LLLT before a training program of combined NMES and BFR of the nondominant extensor carpi radialis longus (ECRL). The control group followed the same protocol but received sham laser therapy. Assessments included maximal voluntary contraction, ECRL mechanical properties, and isometric force tracking for wrist extension.

RESULTS

The LLLT group exhibited a smaller normalized difference in maximal voluntary contraction decrement (-4.01 ± 4.88%) than the control group (-23.85 ± 7.12%) ( P < 0.001). The LLLT group demonstrated a smaller decrease in muscle stiffness of the ECRL compared with the control group, characterized by the smaller normalized changes in frequency ( P = 0.002), stiffness ( P = 0.002), and relaxation measures ( P = 0.011) of mechanical oscillation waves. Unlike the control group, the LLLT group exhibited a smaller posttest increase in force fluctuations during force tracking ( P = 0.014), linked to the predominant recruitment of low-threshold MU ( P < 0.001) without fatigue-related increases in the discharge variability of high-threshold MU ( P > 0.05).

CONCLUSIONS

LLLT preexposure reduces fatigue after combined NMES and BFR, preserving force generation, muscle stiffness, and force scaling. The functional benefits are achieved through fatigue-resistant activation strategies of motor unit recruitment and rate coding.