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To optimize use of available resources, professional academies develop strategies to assess, monitor, and evaluate players as they progress through adolescence toward adulthood. However, few published reports exist using longitudinal study designs to examine performance throughout adolescence and the transition from youth to professional soccer. We examined differences in the age of player recruitment alongside longitudinal performance differences on field-based fitness tests of successful vs. unsuccessful graduates across the entire age spectrum recruited by a professional soccer academy. Altogether, 537 youth soccer players volunteered to participate. We recorded the age of recruitment, biannual fitness test performance, and subsequent success in attaining a senior professional contract at the club across a period of 12 years. Only 53 (10%) of players were successful in obtaining a professional contract, with 68% of players who became professional being recruited at 12 years of age or older. Individuals recruited at an earlier age did not display a higher probability of success in attaining a professional contract. Bayesian regression models reported a consistent interaction between age and group for data on all performance measures. Moreover, "successful" academy graduates only physically outperformed their "unsuccessful" counterparts from age similar to 13-14 years onward, with either no differences in performance, or performance on physical fitness tests favoring "unsuccessful" players prior to this age. Findings suggest that high achievers during childhood and early adolescence may not develop into successful senior professionals, raising concerns about the predictive utility of talent identification models.

Background Exercise referral schemes (ERS) aim to tackle non-communicable disease (NCD) by increasing physical activity levels through prescribed exercise. However, there is a sparsity of knowledge upon what exercises are prescribed and if they are targeted towards tackling NCD. Method Mixed methods were employed. Quantitative data was extracted from exercise prescription cards of 50 participants and were assessed for frequency, intensity, type and time of prescribed exercise. Descriptive measures of aggregate data are expressed as median (range: minimum-maximum). Thematic analysis of semi-structured interviews generated qualitative data on exercise referral instructors’ experiences of prescribing exercise. Results Thirty-eight different types of exercise were prescribed. Median prescription was 4 (1–11) exercises per session, at a moderate intensity. Participants were prescribed a median of 35 (5–70) minutes of aerobic exercise per referral session. Exercise referral instructors prescribed exercise to improve activities of daily living, promote independence and autonomy of participants, rather than explicitly targeting the referral condition. Conclusions Knowledge that prescribed exercises are not explicitly targeted to the referral condition provides critical information in understanding the purpose of exercise prescription. Future evaluations of ERS should be mindful of this, that is, perceived outcomes might not match up to what is being prescribed within ERS.

IntroductionSport-related repetitive subconcussive head impacts (RSHIs) are increasingly thought to be associated with adverse long-term outcomes. However, owing to potentially subtle effects, accurate assessment of harm to the brain as a consequence of RSHI is a major challenge and an unmet need. Several studies suggest that biofluid markers can be valuable objective tools to aid the diagnosis and injury characterisation and help in medical decision-making. Still, by and large, the results have been limited, heterogeneous and inconsistent. The main aims of this scoping review are therefore (1) to systematically examine the extent, nature and quality of available evidence from studies investigating effects of RSHI on fluid biomarkers and (2) to formulate guidelines and identify gaps with the aim to inform future clinical studies and the development of research priorities.Methods and analysesWe will use a comprehensive search strategy to retrieve all available and relevant articles in the literature. The following electronic databases will be systematically searched: MEDLINE (EBSCO host; from 1809 to 2020); Scopus (from 1788 to 2020); SPORTDiscus (from 1892 to 2020); CINAHL Complete (from 1937 to 2020); PsycINFO (from 1887 to 2020); Cochrane Library (to 2020); OpenGrey (to 2020); ClinicalTrials.gov (to 2020) and WHO International Clinical Trials Registry Platform (to 2020). We will consider primarily biomedical studies evaluating the biofluid markers following RSHI. Two independent reviewers will screen articles for inclusion using predefined eligibility criteria and extract data of retained articles. Disagreements will be resolved through consensus or arbitrated by a third reviewer if necessary. Data will be reported qualitatively given the heterogeneity of the included studies. In synthesising the evidence, we will structure results by markers, sample types, outcomes, sport and timepoints.Ethics and disseminationEthics approval is not required. We will submit results for peer-review publication, and present at relevant conferences.

This cross-sectional study explored the differences in sociodemographics, dietary intake, and household foodways (cultural, socioeconomic practices that affect food purchase, consumption, and preferences) of food secure and food insecure older women living in a low-income urban setting in South Africa. Women (n = 122) aged 60–85 years old were recruited, a sociodemographic questionnaire was completed, and food security categories were determined. The categories were dichotomised into food secure (food secure and mild food insecurity) and food insecure (moderate and severe). A one-week quantified food frequency questionnaire was administered. Height and weight were measured to calculate body mass index (BMI, kg/m2). Most participants (&gt, 90%) were overweight/obese, unmarried/widowed, and breadwinners with a low monthly household income. Food insecure participants (36.9%) more frequently borrowed money for food (57.8% vs. 39.0%, p = 0.04), ate less so that their children could have more to eat (64.4%. vs. 27.3%, p = 0.001), and had higher housing density (1.2 vs. 1.0, p = 0.03), compared to their food-secure counterparts. Overall, &lt, 30% of participants met the WHO (Geneva, Switzerland) recommended daily servings of healthy foods (fruits, vegetables, and dairy products), but &gt, 60% perceived that they consumed an adequate amount of healthy foods. The overall low-quality diet of our cohort was associated with poor nutritional perceptions and choices, coupled with financial constraints.

Purpose In this study we measured neural activation (EMG) in four trunk stabilizer muscles and vastus lateralis (VL) in trained and novice participants during a set of squat repetitions to volitional fatigue at 85% 1RM. Methods Forty males were recruited into two groups, novice (NG: n = 21) and experienced (EG: n = 19), according to relative squat 1RM. Participants were tested twice to: (1) determine squat 1RM, and (2) complete a single set of repetitions to volitional fatigue at 85% 1RM. Relative squat 1RM; NG 160% body mass. Neuromuscular activation was measured by EMG for the following: rectus abdominus (RA), external oblique (EO), lumbar sacral erector spinae (LSES), upper lumbar erector spinae (ULES) and VL in eccentric and concentric phase. Completed repetitions, RPE and EMG in repetition 1 and at 20, 40, 60, 80 and 100% of completed repetitions were analysed. Results No group differences were found between number repetitions completed and RPE in repetitions to volitional fatigue at 85% 1RM. Neuromuscular activation increased significantly in all muscle groups in eccentric and concentric phase apart from RA in the eccentric phase. Trunk neuromuscular activation was higher in NG compared to EG and this was significant in EO, LSES and ULES in eccentric phase and LSES in the concentric phase. VL activation increased in both phases with no group differences. Conclusion Trunk neuromuscular activation increases in a fatiguing set of heavy squats regardless of training status. Increased back squat strength through training results in lower neuromuscular activation despite greater absolute external squat loads.

IntroductionOsteoporosis was not a public health concern in black South African (SA) women, until recently when it was reported that the prevalence of vertebral fractures was 9.1% in black compared to 5.0% in white SA women. Accordingly, this study aimed to measure bone mineral density (BMD) of older black SA women and to investigate its association with risk factors for osteoporosis, including strength, muscle and fat mass, dietary intake and objectively measured physical activity (PA).Methods and materialsOlder black SA women (age, 68 (range; 60–85 years) n = 122) completed sociodemographic and quantitative food frequency questionnaires (QFFQ), fasting venous blood samples (25-hydroxycholecalciferol: Vitamin D-25), 24 h urine collection (estimate protein intake), grip strength and PA monitoring (activPAL). Dual-energy x-ray absorptiometry (DXA) scans of the hip (femoral neck and total) and lumbar spine determined BMD and whole-body scans for fat and fat-free soft tissue mass (FFSTM). WHO classifications were used to determine osteopenia (t-score -2.5 to -1), and osteoporosis (t-score < -2.5).ResultsAt the lumbar spine 34.4% of the women (n = 42) had osteopenia and 19.7% (n = 24) had osteoporosis. Osteopenia at the left femoral neck was 32% (n = 40) and osteoporosis was 13.1% (n = 16) of participants. The total left hip BMD indicated osteopenia in 27.9% (n = 34) and osteoporosis in 13.1% (n = 16) of participants. Multinomial regression revealed no differences in age (y) or frequency of falls in the past year between all groups (p = 0.727). Compared to those with normal BMD, participants with osteoporosis at the hip neck and lumbar spine were shorter, weighed less and had a lower body mass index (BMI) (all p < 0.05). When adjusted for height, the osteoporotic group (hip neck and lumbar spine) had lower trunk fat (% whole body), FFSTM (kg) and grip strength (kg), compared to those with normal BMD (p < 0.05). Only protein intake (g; 24 h urine analyses) was lower in women with osteoporosis (all sites) compared to those with normal BMD. Fat, carbohydrate and micronutrient intakes (relative to total daily energy intake), and vitamin D concentrations were not associated with BMD (all sites). Number of daily step count and stepping time (min) were inversely associated with BMI (p < 0.05), but not with BMD (all sites; p > 0.05).DiscussionA high prevalence of osteopenia and osteoporosis was evident at the lumbar spine and hip in older black SA women. This study highlights the importance of strength, body composition, and protein intake in maintaining BMD and preventing the development of osteoporosis in older women.

Skeletal muscle operates as a near-constant volume system; as such muscle shortening during contraction is transversely linked to radial deformation. Therefore, to assess contractile properties of skeletal muscle, radial displacement can be evoked and measured. Mechanomyography measures muscle radial displacement and during the last 20 years, tensiomyography has become the most commonly used and widely reported technique among the various methodologies of mechanomyography. Tensiomyography has been demonstrated to reliably measure peak radial displacement during evoked muscle twitch, as well as muscle twitch speed. A number of parameters can be extracted from the tensiomyography displacement/time curve and the most commonly used and reliable appear to be peak radial displacement and contraction time. The latter has been described as a valid non-invasive means of characterising skeletal muscle, based on fibre-type composition. Over recent years, applications of tensiomyography measurement within sport and exercise have appeared, with applications relating to injury, recovery and performance. Within the present review, we evaluate the perceived strengths and weaknesses of tensiomyography with regard to its efficacy within applied sports medicine settings. We also highlight future tensiomyography areas that require further investigation. Therefore, the purpose of this review is to critically examine the existing evidence surrounding tensiomyography as a tool within the field of sports medicine.

Subjective and objective assessments may be used congruently when making decisions regarding player recruitment in soccer, yet there have been few attempts to examine the level of agreement between these methods. Therefore, we compare levels of agreement between subjective and objective assessments of physical qualities associated with youth soccer performance. In total, 80 male youth soccer players (13.2 ± 1.9 years), and 12 professional coaches volunteered to participate. Players were objectively assessed using five fitness measures: Yo-Yo Intermittent Recovery Test Level 1; Countermovement vertical jump; Functional Movement Screen™; 5/20 m sprint; alongside anthropometric measures. Additionally, coaches subjectively rated each player on the same five physical qualities using 5-point Likert scales. Inter-rater agreement between ratings from lead and assistant coaches was established for each age group. Moreover, Bayesian regression models were fitted to determine how well coach ratings were able to predict fitness test performance. Although inter-rater agreement between lead and assistant coaches was moderate-to-substantial (ω = 0.48-0.68), relationships between coaches subjective rating's and corresponding fitness test performance were only highly related for the highest and lowest performing players. We suggest that while ratings derived from objective and subjective assessment methods may be related when attempting to differentiate between distinct populations, concerns exist when evaluating homogeneous samples using these methods. Our data highlight the benefits of using both types of measures in the talent identification process.

This study aimed to establish between-day reliability and validity of commonly used field-based fitness tests in youth soccer players of varied age and playing standards, and to discriminate between players without (“unidentified”) or with (“identified”) a direct route to professional football through their existing club pathway. Three-hundred-and-seventy-three Scottish youth soccer players (U11–U17) from three different playing standards (amateur, development, performance) completed a battery of commonly used generic field-based fitness tests (grip dynamometry, standing broad jump, countermovement vertical jump, 505 (505COD) and T-Drill (T-Test) change of direction and 10/20 m sprint tests) on two separate occasions within 7–14 days. The majority of field-based fitness tests selected within this study proved to be reliable measures of physical performance (ICC = 0.83–0.97; p less than .01). However, COD tests showed weaker reliability in younger participants (ICC = 0.57–0.79; p less than .01). The field-based fitness testing battery significantly discriminated between the unidentified and identified players; χ2 (7) = 101.646, p less than .001, with 70.2% of players being correctly classified. We have shown field-based fitness tests to be reliable measures of physical performance in youth soccer players. However, results from the 505COD and T-Test change of direction tests may be more variable in younger players, potentially due to complex demands of these tests and the limited training age established by these players. While the testing battery selected in this study was able to discriminate between unidentified and identified players, findings were inconsistent when attempting to differentiate between individual playing standards within the “identified” player group (development vs. performance).

Introduction There is growing concern around the effects of concussion and sub-concussive impacts in sport. Routine game-play in soccer involves intentional and repeated head impacts through ball heading. Although heading is frequently cited as a risk to brain health, little data exist regarding the consequences of this activity. This study aims to assess the immediate outcomes of routine football heading using direct and sensitive measures of brain function. Methods Nineteen amateur football players (5 females; age 22 ± 3 y) headed machine-projected soccer balls at standardized speeds, modelling routine soccer practice. The primary outcome measure of corticomotor inhibition measured using transcranial magnetic stimulation, was assessed prior to heading and repeated immediately, 24 h, 48 h and 2 weeks post-heading. Secondary outcome measures were cortical excitability, postural control, and cognitive function. Results Immediately following heading an increase in corticomotor inhibition was detected; further to these electrophysiological alterations, measurable reduction memory function were also found. These acute changes appear transient, with values normalizing 24 h post-heading. Discussion Sub-concussive head impacts routine in soccer heading are associated with immediate, measurable electrophysiological and cognitive impairments. Although these changes in brain function were transient, these effects may signal direct consequences of routine soccer heading on (long-term) brain health which requires further study., Highlights • Standard soccer heading results in immediate and measurable alterations in brain function. • Changes in short and long term memory function and corticomotor inhibition are detectable immediately after soccer heading. • These changes in brain function after just a single session of heading appear transient. • These data provide direct evidence of immediate brain functional impairment associated with soccer heading. Questions have been raised over whether soccer heading might have an effect on a player's brain, with particular worry over the proposed link between brain injury and increased risk of dementia. However, until now there have been no studies of the immediate effects of heading in soccer directly on brain function. This study found that just a single session of heading practice resulted in temporary impairment of short and long term memory function and in electrophysiological function of the brain. Whether these effects remain temporary after repeated soccer heading exposure and their long-term consequences on brain health must now be investigated.

Context:Assessments of skeletal-muscle functional capacity often necessitate maximal contractile effort, which exacerbates muscle fatigue or injury. Tensiomyography (TMG) has been investigated as a means to assess muscle contractile function after fatigue; however, observations have not been contextualized by concurrent physiological measures.Objective:To measure peripheral-fatigue-induced alterations in mechanical and contractile properties of the plantar-flexor muscles through noninvasive TMG concurrently with maximal voluntary contraction (MVC) and passive muscle tension (PMT) to validate TMG as a gauge of peripheral fatigue.Design:Pre- and posttest intervention with control.Setting:University laboratory.Participants:21 healthy male volunteers.Interventions:Subjects’ plantar flexors were tested for TMG parameters, along with MVC and PMT, before and after either a 5-min rest period (control) or a 5-min electrical-stimulation intervention (fatigue).Main Outcome Measures:Temporal (contraction velocity) and spatial (radial displacement) contractile parameters of the gastrocnemius medialis were recorded through TMG. MVC was measured as an indicator of muscle fatigue, and PMT was measured to assess muscle stiffness.Results:Radial displacement demonstrated a fatigue-associated reduction (3.3 ± 1.2 vs 4.0 ± 1.4 mm, P = .031), while contraction velocity remained unaltered. In addition, MVC significantly declined by 122.6 ± 104 N (P < .001) after stimulation (fatigue). PMT was significantly increased after fatigue (139.8 ± 54.3 vs 111.3 ± 44.6 N, P = .007).Conclusions:TMG successfully detected fatigue, evident from reduced MVC, by displaying impaired muscle displacement accompanied by elevated PMT. TMG could be useful in establishing skeletalmuscle fatigue status without exacerbating the functional decrement of the muscle.

Portable tensiomyography (TMG) and myotonometry (MMT) devices have been developed to measure mechanical and contractile properties of skeletal muscle. The aim of this study was to explore the sensitivity of the aforementioned techniques in detecting a change in passive mechanical properties of the biceps femoris (BF) muscle as a result of change in knee joint angle (i.e. muscle length). BF responses were assessed in 16 young participants (23.4 ± 4.9 years), at three knee joint angles (0°, 45° and 90°), for maximal isometric torque (MIT) along with myo-electrical activity. Contractile and mechanical properties were measured in a relaxed state. Inter-day reliability of the TMG and MMT was also assessed. MIT changed significantly (p < 0.01) across the three angles, so did stiffness and other parameters measured with MMT (p < 0.01). Conversely, TMG could detect changes only at two knee angles (0° and 45°, p < 0.01), when there is enough tension in the muscle. Reliability was overall insufficient for TMG whilst absolute reliability was excellent (coefficient of variation < 5%) for MMT. The ability of MMT more than TMG to detect an inherent change in stiffness can be conceivably exploited in a number of clinical/therapeutic applications that have to do with unnatural changes in passive muscle stiffness.

To evaluate the effect of massage on force production and neuromuscular recruitment.Ten healthy male subjects performed isokinetic concentric contractions on the knee extensors at speeds of 60, 120, 180, and 240 degrees /s. These contractions were performed before and after a 30 minute intervention of either rest in the supine position or lower limb massage. Electromyography (EMG) and force data were captured during the contractions.The change in isokinetic mean force due to the intervention showed a significant decrease (p0.05) at 60 degrees /s and a trend for a decrease (p = 0.08) at 120 degrees /s as a result of massage compared with passive rest. However, there were no corresponding differences in any of the EMG data. A reduction in force production was shown at 60 degrees /s with no corresponding alteration in neuromuscular activity.The results suggests that motor unit recruitment and muscle fibre conduction velocity are not responsible for the observed reductions in force. Although experimental confirmation is necessary, a possible explanation is that massage induced force loss by influencing "muscle architecture". However, it is possible that the differences were only found at 60 degrees /s because it was the first contraction after massage. Therefore muscle tension and architecture after massage and the duration of any massage effect need to be examined.

This study measured how back squat strength (1RM) affected trunk muscle activation in performing squats, squat jump (SJ), and countermovement jump (CMJ). Fifty males, completed two test sessions. Squat 1RM was tested first. Participants were assigned to three groups: (a) strong group (SG), (b) middle group (MG), or (c) weak group (WG), based on relative squat 1RM. Test 2: EMG data were collected for four trunk muscle sites; rectus abdominus, external oblique, lumbar sacral erector spinae, and upper lumbar erector spinae while performing (3 reps) SJ, CMJ, and squats at 65%, 75%, and 95% 1RM. Squat and jump phases were determined from a linear transducer and 30° tertiles for each phase, from a knee goniometer. Normalized root mean square RMS increased significantly with load for each muscle site in both squat phases. Trunk muscle activation was significantly lower in SG vs WG in eccentric and concentric squat phases. Concentric and flight phase RMS in both jumps was lower in SG vs WG. RMS increased significantly for each eccentric tertile and first concentric tertile. Greater squat strength is associated with lower trunk muscle activation in squats and jumps and trunk muscle activation was highest in the two deepest 30° squat segments. In conclusion, back squat strength training to parallel, where top of thighs are horizontal, is an effective method of developing dynamic trunk stability.

Clark, DR, Lambert, MI, and Hunter, AM. Trunk muscle activation in the back and hack squat at the same relative loads. J Strength Cond Res 33(7S): S60-S69, 2019-The hack squat (HS) is likely to produce a greater 1 repetition maximum (1RM) compared with the back squat (BS). This can be attributed to the support of the trunk during the HS compared with no support during BS. This support, however, may compromise trunk muscle activation (TMA), therefore producing different training adaptations. Accordingly, the purpose of this study was to compare 1RM in BS and HS and TMA at 4 relative loads, 65, 75, 85, and 95% of maximal system mass. Ten males completed 3 test sessions: (a) BS and HS 1RM, (b) HS and BS neuromuscular test familiarization, and (c) neuromuscular test for 3 reps at 4 loads for BS and HS. Back squat TMA was significantly greater (p ≤ 0.05) than HS for all muscles and phases except rectus abdominus in concentric phase. Trunk muscle activation increased (p ≤ 0.05) with load in all muscles for both exercises and phases apart from lumbar sacral erector spinae in HS eccentric phase. Mean HS 1RM and submaximal loads were significantly (p < 0.0001) higher than the equivalent BS loads. Duration of the eccentric phase was higher (p < 0.01) in HS than BS but not different in concentric phase. Duration increased significantly (p < 0.01) with load in both exercises and both phases. Despite higher absolute tests loads in HS, TMA was higher in BS. Trunk muscle activation is sensitive to load in both exercises. Back squat is more effective than HS in activating the muscles of the trunk and therefore, arguably more effective in developing trunk strength and stability for dynamic athletic performance.