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Background Sided games (i.e., small sided, medium sided, large sided) involve tactical, technical, physical, and psychological elements and are commonly implemented in soccer training. Although soccer sided-games research is plentiful, a meta-analytical synthesis of external load exposure during sided games is lacking. Objective The objective of this systematic review and meta-analysis was to: (1) synthesize the evidence on high-speed and sprint running exposure induced by sided games in adult soccer players, (2) establish pooled estimates and intra-individual reliability for high-speed and sprint running exposure, and (3) explore the moderating effects of game format and playing constraints. Methods A literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Four databases (PubMed/MEDLINE, Scopus, SPORTDiscus, Web of Science Core Collection) were systematically searched up to 25 January, 2022. Eligibility criteria were adult soccer players (population); training programs incorporating sided games (intervention); game manipulations including number of players, pitch dimension, and game orientation (comparator); and high-speed, very high-speed, and sprint relative (m$$\cdot$$ · min−1) running distances and associated intra-individual reliability (outcome). Eligible study risk of bias was evaluated using RoBANS. Pooled estimates for high-speed and sprint running exposure, and their intra-individual reliability, along with the moderating effect of tracking device running velocity thresholds, pitch dimension (i.e., area per player), and game orientation (i.e. score or possession), were determined via a multi-level mixed-effects meta-analysis. Estimate uncertainty is presented as 95% compatibility intervals (CIs) with the likely range of relative distances in similar future studies determined via 95% prediction intervals. Results A total of 104 and 7 studies met our eligibility criteria for the main and reliability analyses, respectively. The range of relative distances covered across small-sided games, medium-sided games, and large-sided games was 14.8 m$$\cdot$$ · min−1 (95% CI 12.3–17.4) to 17.2 m$$\cdot$$ · min−1 (95% CI 13.5–20.8) for high-speed running, 2.7 m$$\cdot$$ · min−1 (95% CI 1.8–3.5) to 3.6 m$$\cdot$$ · min−1 (95% CI 2.3–4.8) for very high-speed running, and 0.2 m$$\cdot$$ · min−1 (95% CI 0.1–0.4) to 0.7 m$$\cdot$$ · min−1 (95% CI 0.5–0.9) for sprinting. Across different game formats, 95% prediction intervals showed future exposure for high-speed, very high-speed running, and sprinting to be 0–46.5 m$$\cdot$$ · min−1, 0–14.2 m$$\cdot$$ · min−1, and 0–2.6 m$$\cdot$$ · min−1, respectively. High-speed, very high-speed running, and sprinting showed poor reliability with a pooled coefficient of variation of 22.8% with distances being moderated by device speed thresholds, pitch dimension, and game orientation. Conclusions This review is the first to provide a detailed synthesis of exposure and intra-individual reliability of high-speed and sprint running during soccer sided games. Our estimates, along with the moderating influence of common programming variables such as velocity thresholds, area per player, and game orientation should be considered for informed planning of small-sided games, medium-sided games, and large-sided games soccer training. Clinical Trial Registration Open Science Framework available through https://osf.io/a4xr2/.

The aim of this study was to compare internal and external load profiles of different game profile-based training (GPBT) formats among elite young football players. Twenty-one participants (age: 18.7 ± 0.6 years) performed three sessions of three GPBT formats, which were matched for training volume but structured with different high-speed running and sprint demands: i) performed along linear paths (GPBT-L); ii) performed as repetitive actions of short distance including many multi-directional changes of direction (GPBT-S) and, iii) a combination of the other two protocols, that is linear high-speed runs and sprint efforts with a single change of direction (GPBT-M). External load outputs were collected using GPS units, physiological and perceptual responses were monitored with heart rate (HR) monitors, and ratings of perceived exertion (RPE), respectively. While no differences were found between formats for HR and RPE, distinct external load profiles were observed for high-speed running (HSD) and sprint distances (SD), (GPBT-LGPBT-MGBPT-S, all p0.05), and high-intensity acceleration and deceleration efforts (HIE), (GPBT-SGPBT-MGPBT-L, all p0.05). Moreover, the GPBT-S format was characterized by greater intra-session variability for HSD, SD, and HIE (CV% = 24.2%, 16.5% and 20.4%, respectively) and inter-session variability for HSD and SD (CV% = 10% and 15.7%, respectively) compared to the other two formats. Considering their load profiles and the associated reliability scores, football practitioners can implement GPBT formats interchangeably to elicit necessary internal load responses and selectively to prioritize specific external load outputs.

We quantified on pitch external loading of English Premier League (EPL) academy soccer players (n=76; U12-U18 age groups) over an entire competitive season. Mean accumulative weekly duration and total distance, respectively, was similar in the U12 (329±29 min; 19.9±2.2 km), U13 (323±29 min; 20.0±2.0 km) and U14 (339±25 min; 21.7±2.0 km; P>0.05 for all comparisons) age-groups, though all teams were less than U15 (421±15 min; 26.2±2.1 km), U16 (427±20 min; 25.9±2.5 km) and U18 (398±30 min; 26.1±2.6 km) players (P0.05 for all pairwise comparisons) though all squads were less than U15 (657±242 m and 49±98 m), U16 (749±152 m and 95±55 m) and U18 (979±254 m and 123±56 m) age-groups (P

Purpose This study explored the validity and reliability of the physiological and perceptual responses elicited during a novel treadmill-based Soccer Referee Simulation (SRS). Methods Following the collection of baseline measures and habituation procedures, eight sub-elite soccer referees completed a single trial of the SRS whereby measures of heart rate (HR), oxygen uptake (V̇O2), blood lactate concentrations ([La−]b), and differential ratings of perceived exertion (RPE) were obtained. Referees’ HR responses were also monitored during a series of competitive matches (5 match observations per referee). For the reliability aspect of the investigation, eight well-trained males with soccer playing experience and a comparable physiological profile were initially habituated, and thereafter completed three separate trials of the SRS during which the reliability of the selected outcome variables were ascertained. Trials were separated by 3–7 days and performed under standardised conditions. Results No differences were evidenced between the SRS and match play in relation to measures of mean HR (P = 0.444; ES = 0.29), peak HR (P = 0.074; ES = 0.74), or HR-based training impulse (P = 0.498; ES = 0.25). Additionally, no systematic differences were detected between reliability trials for any of the measured outcome variables (P ≥ 0.293), whilst good levels of reliability were observed for measures of mean HR (ICC = 0.94; CV = 3.1%), peak HR (ICC = 0.93; CV = 2.2%), HR-based training impulse (ICC = 0.95; CV = 10.0%), mean V̇O2 (ICC = 0.95; CV = 2.6%); [La−]b (ICC ≥ 0.89; CV ≤ 11.5%), and differential RPE (ICC ≥ 0.94; CV ≤ 15.1%). Conclusion The SRS represents a valid and reliable protocol that closely replicates the physiological and decision-making demands of soccer refereeing.

The goal of professional soccer academies is to develop players who can progress and represent their first team or that can be sold for financial gain. As an academy player transitions through the academy pathway (i.e. from under, U9 to U23), they undergo distinct phases of growth and maturation that result in anatomical (e.g. an increase in stature and body mass), physiological (e.g. an increase in growth hormone, insulin-like growth factor 1, testosterone and thyroid hormones) and metabolic changes (e.g. increased glycolytic capabilities). The collective result of such changes are likely to influence such daily energy requirements. However, unlike professional adult players, the body composition, physical loading patterns and associated daily energy expenditure have not yet been quantified in academy soccer players. A detailed understanding of such parameters is fundamental in order to promote growth and maturation whilst also maximising each players physical and technical development. With this in mind, the aim of this thesis was to determine the energy requirements of male academy soccer players from the English Premier League of different chronological and biological ages. The aim of Study 1 (Chapter 4) was to assess body composition and resting metabolic rate in a cohort of academy soccer players. In a cross-sectional design, ninety-nine males from a Category One English Premier League academy (U12-U23 age-groups) underwent assessments of body composition (dual-energy X-ray absorptiometry, DXA) and resting metabolic rate (indirect calorimetry). Fat-free mass increased between the U12 (31.6 ± 4.2 kg) and U16 (56.3 ± 5.3 kg) age-groups after which no further increases occurred. Resting metabolic rate in the U12 (1655 ± 195 kcalday-1), U13 (1720 ± 205 kcalday-1) and U14 (1846 ± 218 kcalday-1) age-groups was significantly lower than the U15 (1957 ± 128 kcalday-1), U16 (2042 ± 155 kcalday-1), U18 (1875 ± 180 kcalday-1) and U23 (1941 ± 197 kcalday-1) age-groups. These data provide the first report of differences in body composition and resting metabolic rate in academy soccer players (as assessed via DXA and indirect calorimetry, respectively) and demonstrate that the growth and maturation occurring between U12-U16 significantly increases resting energy requirements. Having quantified body composition and resting metabolic rate in Study 1 (Chapter 4), the aim of Study 2 (Chapter 5) was to determine the typical weekly training and match loading patterns of academy soccer players. Over the course of an entire competitive season, weekly training and match load was quantified using global positioning system technology in 76 soccer players from a Category One English Premier League academy (U12-U18 age-groups). Weekly training and match volume (i.e. duration and total distance) was similar in the U12 (329 ± 29 min; 19.9 ± 2.2 km), U13 (323 ± 29 min; 20.0 ± 2.0 km) and U14 (339 ± 25 min; 21.7 ± 2.0 km) age-groups, but was lower than the U15 (421 ± 15 min; 26.2 ± 2.1 km), U16 (427 ± 20 min; 25.9 ± 2.5 km) and U18 (398 ± 30 min; 26.1 ± 2.6 km) age-groups. Weekly high-speed running and sprint distance (i.e. intensity) were comparable in the U12 (220 ± 95 m and 6 ± 9 m respectively), U13 (331 ± 212 m and 6 ± 27 m) and U14 (448 ± 193 m and 21 ± 29 m) age-groups was similar, but less than the U15 (657 ± 242 m and 49 ± 98 m), U16 (749 ± 152 m and 95 ± 55 m) and U18 (979 ± 254 m and 123 ± 56 m) age-groups. These data provide the first 4 report to objectively assess accumulative training and match loads in academy soccer players and demonstrate that the absolute loads are progressive in nature throughout the academy pathway. Given the progressive changes in body composition (Study 1, Chapter 4), resting metabolic rate (Study 1, Chapter 4) and physical loading patterns (Study 2, Chapter 5), the aim of Study 3 (Chapter 6) was to quantify the total daily energy expenditure of academy soccer players with different chronological and biological ages. Energy expenditure (doubly labelled water) and energy intake (remote food photographic method) was assessed over a 14-day in-season period in 24 soccer players from a Category One English Premier League academy (U12/13, n=8; U15, n=8; U18, n=8). U18 players presented with greater total energy expenditure (3586 ± 487 kcalday-1) than both the U15 (3029 ± 262 kcalday-1) and U12/13 players (2859 ± 265 kcalday-1), though no differences were evident between the U12/13 and U15 age-groups. Within age-groups, no differences were apparent between energy intake and total energy expenditure, whilst U18 players (3180 ± 279 kcalday-1) reported a higher energy intake than both the U15 (2821 ± 338 kcalday-1) and U12/13 (2659 ± 187 kcalday-1) players. In some individuals (evident in all age-groups) total energy expenditure was greater than that previously observed in adult English Premier League soccer players (3566 ± 585 kcalday-1). In summary, the data presented in this thesis provides the first report to simultaneously quantify body composition, resting metabolic rate, physical loading patterns and total daily energy expenditure of academy soccer players. Importantly, these data demonstrate that players’ absolute daily energy expenditure progressively increase as they become more biologically mature, likely a reflection of increased fat-free mass and physical loading patterns. From a practical perspective, these data will assist in developing population specific sport nutrition guidelines.

Female soccer has seen a substantial rise in participation, as well as increased financial support from governing bodies over the last decade. Thus, there is an onus on researchers and medical departments to develop a better understanding of the physical characteristics and demands, and the health and performance needs of female soccer players. In this review, we discuss the current research, as well as the knowledge gaps, of six major topics: physical demands, talent identification, body composition, injury risk and prevention, health and nutrition. Data on female talent identification are scarce, and future studies need to elucidate the influence of relative age and maturation selection across age groups. Regarding the physical demands, more research is needed on the pattern of high-intensity sprinting during matches and the contribution of soccer-specific movements. Injuries are not uncommon in female soccer players, but targeting intrinsically modifiable factors with injury prevention programmes can reduce injury rates. The anthropometric and physical characteristics of female players are heterogeneous and setting specific targets should be discouraged in youth and sub-elite players. Menstrual cycle phase may influence performance and injury risk; however, there are few studies in soccer players. Nutrition plays a critical role in health and performance and ensuring adequate energy intake remains a priority. Despite recent progress, there is considerably less research in female than male soccer players. Many gaps in our understanding of how best to develop and manage the health and performance of female soccer players remain.

This study sought to: (1) document the multifaceted training practices of soccer officials in relation to their role and officiating category; and (2) explore the association between the officials’ training practices and perceptions of the attributes pertinent to optimal performance. Field referees and assistant referees at officiating categories 1–3 ( n = 173) with the Scottish Football Association were invited to participate in this national cross-sectional study. Using the Referee Training Activity Questionnaire (RTAQ), officials reported the volume and type of training engaged in during a 2-week in-season period. Respondents’ perceptions of the skills pertinent to performance were also explored using a 7-point Likert scale ( 1 = not at all important; 7 = extremely important), with the frequency in which they trained these skills assessed using a 5-point Likert Scale ( 1 = less than once a month; 5 = more than once a week). Ninety-one responses were received, representing a 52.6% response rate. Irrespective of their role or level of professional attainment, the officials’ training was focused mostly on physical conditioning, with significantly less time apportioned to decision-making ( P

Cardiac modifications to training are a product of the genetic pre-disposition for adaptation and the repetitive haemodynamic loads that are placed on the myocardium. Elite pre-adolescent athletes are exposed to high-intensity training at a young age with little understanding of the physiological and clinical consequences. It is unclear how right ventricular (RV) structure and function may respond to this type of stimulus. The aim of this study was to compare RV structure and strain across the cardiac cycle and within individual segments in elite soccer players (SP) and controls (CON). Methods: Twenty-two highly trained, male pre-adolescent SP and 22 age-and sex-matched recreationally active individuals CON were investigated using 2D echocardiography, including myocardial speckle tracking to assess basal, mid-wall, apical and global longitudinal strain and strain rate during systole (SRS) and diastole (SRE and SRA). Results: greater RV cavity size was identified in the SP compared to CON (RVD1 SP: 32.3 ± 3.1 vs. CON: 29.6 ± 2.8 (mm/m2)0.5; p = 0.005). No inter-group differences were noted for peak global RV strain (SP: − 28.6 ± 4.9 vs CON: − 30.3 ± 4.0%, p = 0.11). Lower mid-wall strain was demonstrated in the SP compared to CON (SP: − 27.9 ± 5.8 vs. CON: − 32.2 ± 4.4%, p = 0.007). Conclusion: Soccer training has the potential to increase RV size in pre-adolescent players. The unique segmental analyses used in this study have identified inter-group differences that were masked by global strain evaluations. The clinical and physiological implications of these findings warrant further investigation.

Purpose: To examine the reliability of HR measures obtained during the 6 min Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1), and following a 3 min passive recovery, within a group of highly trained youth soccer players.\ud Methods: Eight players, completed three separate 6 min Yo-Yo IR1 tests, with a passive recovery, over a two week period. Measures of absolute heart rate (bpm) and relative HR (%HRmax) were obtained at the 3rd and 6th min of the test, with measures relative to the end HR (%HRend) 10, 20, 30, 60, 90 and 180 seconds, during the 3 min passive recovery. Variability in HR measures were assessed across successive trials (trial 1 vs. 2 and trial 2 vs. 3) and across all 3 trials, using the intraclass correlation coefficient (ICC), coefficient of variation (CV) and typical error (TE). Results: HR measures obtained during the 6 min Yo-Yo IR1 test displayed good levels of reliability (ICC: 0.95-0.98, CV: 1.1-1.3% and TE: 0.96-2.44).\ud Results, display a potential learning effect, with lower levels of variability between trial 2 vs. trial 3. Examination of %HRend obtained during the passive 3 min recovery demonstrated an increased variance, as the passive recovery period progressed.\ud Conclusion: The 6 min Yo-Yo IR1 test presents a novel and potentially practical approach to regularly assessing youth soccer players’ physical response to intermittent exercise. Practitioners and researchers should however, consider the need for appropriate familiarisation when undertaking this test.

Purpose: The purpose of the study was to examine differences in measures of cardiorespiratory fitness and determinants of running economy with respect to maturity status in a group of highly trained youth soccer players. Methods: A total of 21 highly trained youth soccer players participated in this study. On separate visits, players’ peak oxygen uptake (VO2peak), running economy at 3 different speeds [8 km·h−1, 80% gaseous exchange threshold (GET), and 95% GET], and pulmonary oxygen uptake (VO2) kinetics were determined. Players also performed a Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1). Players were categorized as either “pre-PHV” (peak height velocity) or “mid-PHV” group using the measure of maturity offset. Independent t tests and Cohen’s d effect sizes were then used to assess differences between groups. Results: The mid-PHV group was significantly taller, heavier, and advanced in maturity status. Absolute measures of VO2peak were greater in the mid-PHV group; however, when expressed relative to body mass, fat-free mass, and theoretically derived exponents, VO2peak values were similar between groups. Pre-PHV group presented a significantly reduced VO2 response, during relative submaximal running speeds, when theoretically derived exponents were used, or expressed as %VO2peak. VO2 kinetics (tau) were faster during a low (standing) to moderate (95% GET) transition in the pre-PHV group. Yo-Yo IR1 performance was similar between groups. Conclusion: Although measures of VO2peak and Yo-Yo IR1 performance are shown to be similar between groups, those categorized as pre-PHV group display a superior running economy at relative submaximal running speeds and faster taus during a low to moderate exercise transition than their more mature counterparts.

BACKGROUND: The objective of this study was to investigate left ventricular (LV) circumferential strain responses to incremental cycling and isometric knee extension exercises.\ud METHODS: Twenty-six healthy male participants (age = 30 ± 6 years) were used to study LV global (GCS) and regional circumferential strain at the apex (ACS) and base (BCS) during incremental cycling at 30% and 60% work rate maximum (Wmax ) and short-duration (15 seconds contractions) isometric knee extensions at 40% and 75% maximum voluntary contraction (MVC) using two-dimensional speckle tracking echocardiography.\ud RESULTS: During cycling (n = 22), GCS increased progressively from rest to 60% Wmax (-22.85 ± 3.26% to -29.87 ± 2.59%, P < .01). ACS increased from rest to 30% Wmax (-26.29 ± 4.84% to -36.84 ± 6.94%, P < .01) and then remained unchanged to 60% Wmax (-40.72 ± 4.06%, P = .068). BCS decreased from rest to 30% Wmax (-19.41 ± 2.79 to -17.51 ± 4.66%, P = .05) and then remained unchanged to 60% Wmax . During isometric knee extension (n = 23), GCS decreased from rest to 40% MVC (-22.63 ± 3.46 to -20.10 ± 2.78%, P < .05) and then remained unchanged to 75% MVC. Similarly, BCS decreased from rest to 40% MVC (-19.21 ± 2.58% to -13.55 ± 3.45%, P < .01) and then remained unchanged, whereas ACS did not change with exercise intensity (rest, -26.05 ± 5.34%; 40% MVC, -26.64 ± 4.53% and 75% MVC -27.22 ± 5.34%, all P > .05).\ud CONCLUSION: Global circumferential strain increased stepwise during incremental cycling, mediated by the apex with trivial changes at the base. In contrast, GCS decreased during the isometric knee extension to 40% MVC and then plateaued, due to decreased BCS as ACS was maintained. A novel finding is that the GCS response appears to be exercise modality dependant and is the consequence of region-specific changes.

Purpose: The purpose of the study was to assess the validity, objectivity, and reliability of a Soccer-Specific Behaviour Measurement Tool (S-SBMT) in relation to the soccer philosophy of a Category One Premier League soccer academy. Methods: A 30 minute, 8 vs. 8 small-sided game (SSG), played by the U12 squad of the participating academy was used for analyses. Validity was ensured through formulating the S-SBMT definitions with experienced soccer coaches from the same soccer academy. Percentage agreement with a reference value of ±1, 95% Confidence Intervals, median sign and Yule’s Q were used to assess objectivity and reliability. Results: High levels of objectivity were found for the number of passes (98.8% agreement), runs with the ball (97.5% agreement), and goal attempts (100%). Reduced objectivity was apparent for forward zonal transitions (75.3%), along with tackles (70.4%), interceptions, (63%), and loose balls (48.1%). Reliability was tested after 1- and 4-weeks, with levels of percentage agreement found to be above the 85% acceptable threshold for most behaviours (passing = 95.1%, runs with the ball = 92.6%, goal attempts = 100%, tackles = 100%). Conclusions: The study demonstrated acceptable objectivity and reliability for S-SBMT behaviours and these findings demonstrate the potential utility of the S-SBMT in monitoring technical actions in a Category One Premier League soccer academy, and a methodological process for other academies to follow in ensuring the quality of performance data.

Aims This study aimed to evaluate left ventricular structure, function and mechanics, in highly-trained, pre-adolescent soccer players compared with age- and sex-matched controls. Design The study design was a prospective, cross-sectional comparison of left ventricular structure, function and mechanics. Methods Twenty-two male soccer players from two professional youth soccer academies (age: 12.0 ± 0.3 years) and 22 recreationally active controls (age: 11.7 ± 0.3 years) were recruited. Two-dimensional conventional and speckle tracking echocardiography were used to quantify left ventricular structure, function and peak/temporal values for left ventricular strain and twist, respectively. Results End-diastolic volume index was larger in soccer players (51 ± 8 mm/(m2)1.5 vs. 45 ± 6 mm/(m2)1.5; p = 0.007) and concentricity was lower in soccer players (4.3 ± 0.7 g/(mL)0.667 vs. 4.9 ± 1.0 g/(mL)0.667; p = 0.017), without differences in mean wall thickness between groups (6.0 ± 0.4 mm vs. 6.1 ± 0.5 mm; p = 0.754). Peak circumferential strain at the base (–22.2% ± 2.5% vs. –20.5% ± 2.5%; p = 0.029) and papillary muscle levels (–20.1% ± 1.5% vs. –18.3% ± 2.5%; p = 0.007) were greater in soccer players. Peak left ventricular twist was larger in soccer players (16.92° ± 7.55° vs. 12.34° ± 4.99°; p = 0.035) and longitudinal early diastolic strain rate was greater in soccer players (2.22 ± 0.40 s–1 vs. 2.02 ± 0.46 s–1; p = 0.025). Conclusions Highly-trained soccer players demonstrated augmented cardiac mechanics with greater circumferential strains, twist and faster diastolic lengthening in the absence of differences in wall thickness between soccer players and controls.

Purpose The interaction of ageing and exercise training status on left-ventricular (LV) peak strain is unclear. Additionally, strain analysis across the entire cardiac cycle facilitates a more detailed assessment of deformation, yet this has not been implemented to characterize the ageing LV and in association with training status. This study investigated healthy ageing and training status on LV systolic and diastolic strain utilizing novel echocardiographic applications. Methods Forty healthy males were included and allocated into four groups; young recreationally active (YRA, n = 9; 28 ± 5 years), old recreationally active (ORA, n = 10; 68 ± 6), young trained (YT, n = 10; 27 ± 6 years), and old trained (OT, n = 11, 64 ± 4 years) groups. Two-dimensional speckle-tracking echocardiography was performed to ascertain peak LV longitudinal and circumferential strain (base and apex) strain within each myocardial layer and at 5% increments across the cardiac cycle. Results Older groups had lower diastolic longitudinal lengthening and circumferential expansion between 40–85% mid-diastole, regardless of training status (P 0.05). Longitudinal and circumferential (base and apex) peak and layer-specific strain did not differ between groups (P > 0.05). Conclusion Novel applications of diastolic strain revealed lower age-associated LV longitudinal lengthening and circumferential expansion in older age. Yet, diastolic strain profiles did not differ based on chronic habits of exercise training and, thus, older trained men did not demonstrate an attenuation of age-associated differences in mid-diastolic LV strain. Electronic supplementary material The online version of this article (10.1007/s00421-020-04418-1) contains supplementary material, which is available to authorized users.

Dello Iacono, A, Beato, M, and Unnithan, V. Comparative effects of game profile-based training and small-sided games on physical performance of elite young soccer players. J Strength Cond Res 35(10): 2810-2817, 2021-This study was designed to investigate and compare the effects of game profile-based training (GPBT) and small-sided game (SSG) training on physical performances of elite youth soccer players during the in-season period. Twenty young soccer players (18.6 ± 0.6) were randomly assigned to either GPBT or SSG protocols performed twice a week for 8 weeks. The GPBT consisted of 2 sets of 6-10 minutes of intermittent soccer-specific circuits. The SSG training consisted of 3-5 sets of 5 vs. 5 SSGs played on a 42 × 30-m pitch. Before and after the training program, the following physical performances were assessed: repeated sprint ability, change of direction (COD), linear sprinting on 10 m and 20 m, countermovement jump, and intermittent running (YYIRL1). Significant improvements were found in all the assessed variables after both training interventions (p0.05). The GPBT group improved more than the SSG group in the 10-m and 20-m sprint tests by 2.4% (g = 0.4; small effect) and 4% (g = 0.9; large effect), respectively. Conversely, the SSG group jumped 4% higher (g = 0.4; small effect) and resulted 6.7% quicker than the GPBT (g = 1.5; large effect) in completing the COD task. These results suggest both GPBT and SSGs to be effective for fitness development among elite young soccer players during the competitive season. More importantly, these 2 conditioning methodologies may be considered in terms of specificity for selectively improving or maintaining specific soccer fitness-related performances in the latter phase of the season.

There were two aims of this study: first, to investigate physical fitness and match performance differences between under-16 (U16) and under-18 (U18) female basketball players, and second, to evaluate the relationship between physical fitness and game-related performances. Twenty-three young, female, elite Spanish basketball players (16.2 1.2 years) participated in the study. The sample was divided into two groups: U16 and U18 players. The average scores from pre- and post-season physical fitness measurements were used for subsequent analyses. Anthropometric variables were also measured. To evaluate game performance, game-related statistics, including the number of games and minutes played, points, rebounds, assists, steals and blocks per game, were recorded for every competitive match in one season. When anthropometric and physical performance variables were compared between groups, the U18 group demonstrated significantly (p

Purpose: To examine the relationship between oxygen uptake kinetics (VO2 kinetics) and physical measures associated with soccer match-play, within a group of highly trained youth soccer players.\ud Methods: Seventeen highly trained youth soccer players (age: 13.3 ± 0.4 yr, self-assessed Tanner Stage: 3 ± 1) volunteered for the study. Players initially completed an incremental treadmill protocol to exhaustion, to establish gaseous exchange threshold (GET) and VO2max (59.1 ± 5.4 mL.kg-1.min-1). On subsequent visits players completed a step transition protocol from, rest–moderate intensity exercise, followed by an immediate transition from moderate–severe intensity exercise (moderate: 95%GET, severe: 60%∆), during which VO2 kinetics were determined. Physical soccer-based performance was assessed using a maximal Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1) and via GPS derived measures of physical soccer performance during soccer match-play, 3 2 x 20min, 11 v 11 matches, to gain measures of physical performance during soccer match-play. \ud Results: Partial correlations revealed significant inverse relationships between the unloaded to moderate transition time constant (tau) and: Yo-Yo IR1 performance (r = -0.58, P = 0.02) and GPS variables (Total distance (TD): r = - 0.64, P = 0.007, High speed running (HSR): r = - 0.64, P = 0.008, High speed running efforts (HSReff): r = - 0.66, P = 0.005). \ud Conclusion: Measures of VO2 kinetics are related to physical measures associated with soccer match-play and could potentially be used to distinguish between those of superior physical performance, within a group of highly-trained youth soccer players.

The purpose of this study was to assess the relationship between: Peak oxygen uptake (VO2max) and running economy (RE) with physical measures associated with elite youth soccer performance obtained during soccer match-play. Seventeen highly trained youth soccer players (age: 13.3±0.4y) volunteered to participate. Initially player’s ventilatory threshold (VT) and VO2max was established using a treadmill protocol. On the subsequent visit, players ran for 4 min, at three different speeds (8km/h, 80%VT and 95%VT). Physical soccer-based performance was assessed using a maximal Yo-Yo IR1 and via Global positioning systems (GPS) derived variables obtained during three, 2x20min, 11 v 11 soccer matches. Partial correlations revealed significant relationships between relative VO2max and measures of physical soccer performance (r = 0.54–0.88). Moreover, measures of ventilatory equivalent (VEVO2), a determinant of RE, at all sub-maximal exercise intensities were inversely related to the volume (m) and percentage (%) of very high intensity activities. Current findings emphasise the need for high levels of cardio-respiratory fitness in high level youth soccer players, with superior levels of fitness being associated with a greater amount of high and very high intensity activity during soccer match-play.

Doncaster, G and Unnithan, V. Between-game variation of physical soccer performance measures in highly trained youth soccer players. J Strength Cond Res 33(7): 1912-1920, 2019-To assess the between-game variation in measures of physical performance during 11 vs. 11 soccer match play, over a short period, in highly trained youth soccer players. A single-cohort, observational, study design was used. Physical match performance data were collected from 17, male, highly trained, youth soccer players (age, 13.3 ± 0.4 years) over 3, 2 × 20 minutes, 11 vs. 11 matches. Using 10-Hz global positioning systems, the variables selected for analyses were total distance (TD), high-speed running (HSR), very high-speed running (VHSR), number of high-speed running efforts (HSReff), and number of very high-speed running efforts (VHSReff). Match data were also separated into cumulative 5-minute epochs, to identify the peak 5-minute epoch and the mean of the cumulative 5-minute epochs for each match. Variability was quantified using the coefficient of variation (CV), standard error of measurement, and intraclass correlation coefficient. Between- and within-player smallest worthwhile changes (SWC) were also calculated for each variable to aid in the interpretation of the data. Analysis of the variance between games reported a low CV for TD (3.8%) but larger CVs for HSR (33.3%), HSReff (35.4%), and VHSR and VHSReff (59.6 and 57.4%, respectively). Analysis of 5-minute epochs (peak and average) found an increase in the CVs beyond that of the values reported for the whole match. Between-player SWC in high-intensity physical performance data ranged from 24.7 to 42.4%, whereas within-player SWC ranged from 1.2 to 79.9%. The between-game variability of high-intensity and very high-intensity activities in youth soccer players, across 3 soccer matches over a short period (2 weeks), is relatively "large" and specific to the individual, thus highlighting the need for caution when interpreting physical performance data between games and players.

Physical frailty has been regarded as a precursor state to disability and dependence on others for daily activities. Frail individuals are considered to be the group of patients that presents the most complex and challenging problems to health care professionals. The purpose of this study was to evaluate whether a 12-week functional circuit training program (FCT) could reduce self-reported fear of falling and improve health status in a group of physically frail community-dwelling older individuals. Fifty-one individuals (31 F, 20 M), mean age (SD) 84 (2.9) years old, were considered frail and tested at week 0 and randomly assigned into two groups (intervention group, FCT = 26; control group, CG = 25). FCT underwent a structured 12-week FCT program, which focused on a combination of functional balance and lower-body strength-based exercises. CG met once a week for health education meetings. Measures of self-reported fear of falling (Activities-specific Balance Confidence scale) and health status (SF-12) were assessed at week 0, 12 and 36. All longitudinal analyses for continuous variables that were measured at the three time points (week 0, 12 and 36) were performed using linear mixed modeling. FCT participants had greater improvements than those in the CG in fear of falling and self-reported physical function, physical composite score and mental composite score; these improvements were maintained in the week 36 follow-up, with significant group-by-time interactions by the end of the study. These data indicate that a FCT program is effective in improving self-reported measures of fear of falling and health status in a group of physically frail individuals.

To compare the phase II oxygen uptake time constant (τV'O(2)) and V'O(2) mean response time (V'O(2)MRT) in overweight (OW) and non-OW (NO) children during moderate intensity exercise.Between subjects where participants completed a maximal ramp exercise test on an electromagnetically braked cycle ergometer to determine peak V'O(2) (V'O(2peak)) and gas exchange threshold (GET). Gas exchange was measured breath-by-breath using a mass spectrometer. On subsequent visits, 6 square-wave transitions (2 per day) from 0 W to 90% GET were completed. Individual phase II τV'O(2) and V'O(2)MRTs were estimated from time aligned average V'O(2) traces.Eleven OW (11.8±0.4 years) and 12 NO (11.9±0.4 years) children were recruited to the study. The OW group was significantly heavier (62.9±9.7 vs 39.4±5.8 kg, P0.001), taller (1.58±0.05 vs 1.47±0.07 m, P0.001) and had a higher body mass index (25.8±3.4 vs 18.3±1.8 kg m(-2), P0.001).Both τV'O(2) (30.2±9.6 vs 22.8±7.1 s, P0.05) and V'O(2)MRT (43.5±10.7 vs 36.3±5.3 s, P0.05) were significantly slower in OW compared with NO children; absolute V'O(2peak) was higher in the OW compared with NO group (2.23±0.04 vs 1.74±0.04 l min(-1), P0.05); mass relative V'O(2peak) was lower in OW compared with NO children (35.9±8.3 vs 43.8±6.2 ml kg(-1) min(-1), P0.05); allometrically scaled V'O(2peak) was similar between OW and NO groups whether relative to body mass(0.67) (139.8±29.1 vs 147.2±23.9 ml kg(-67) min(-1)) or stature(3) (576.0±87.2 vs 544.9±84.9 ml m(-3) min(-1)) (P0.05); absolute V'O(2) at GET was similar between OW and NO groups (0.94±0.24 vs 0.78±0.27 l min(-1), P0.05); GET expressed as percentage of V'O(2peak) was similar between the groups (42.0±0.1 vs 44.8±0.1%, P0.05).These findings demonstrate impairment in the factors determining V'O(2) kinetics in OW children at a relatively young age. Furthermore, assessment of cardiorespiratory fitness using peak exercise values is likely to be misleading and not useful when designing exercise programmes for OW children.

Background. Inspiratory muscle training (IMT) has been shown to improve inspiratory muscle function, lung volumes (vital capacity [VC] and total lung capacity [TLC]), work capacity, and power output in people who are healthy; however, no data exist that demonstrate the effect of varying intensities of IMT to produce these outcomes. Objectives. The purpose of this study was to evaluate the impact of IMT at varying intensities on inspiratory muscle function, VC, TLC, work capacity, and power output in people who are healthy. Design. This was a randomized controlled trial. Setting. The study was conducted in a clinical laboratory. Participants. Forty people who were healthy (mean age=21.7 years) were randomly assigned to 4 groups of 10 individuals. Interventions. Three of the groups completed an 8-week program of IMT set at 80%, 60%, and 40% of sustained maximum inspiratory effort. Training was performed 3 days per week, with 24 hours separating training sessions. A control group did not participate in any form of training. Measurements. Baseline and posttraining measurements of body composition, VC, TLC, inspiratory muscle function (including maximum inspiratory pressure [MIP] and sustained maximum inspiratory pressure [SMIP]), work capacity (minutes of exercise), and power output were obtained. Results. The participants in the 80%, 60%, and 40% training groups demonstrated significant increases in MIP and SMIP, whereas those in the 80% and 60% training groups had increased work capacity and power output. Only the 80% group improved their VC and TLC. The control group demonstrated no change in any outcome measures. Limitations. This study may have been underpowered to demonstrate improved work capacity and power output in individuals who trained at 40% of sustained maximum inspiratory effort. Conclusion. High-intensity IMT set at 80% of maximal effort resulted in increased MIP and SMIP, lung volumes, work capacity, and power output in individuals who were healthy, whereas IMT at 60% of maximal effort increased work capacity and power output only. Inspiratory muscle training intensities lower than 40% of maximal effort do not translate into quantitative functional outcomes.

Exercise training results in a speeding of pulmonary oxygen uptake (V˙ O2) kinetics at the onset of exercise in adults; however, only limited research has been conducted with children and adolescents. Purpose: The aim of the present study was to examine V˙ O2 and muscle deoxygenation kinetics in trained and untrained male adolescents. Methods: Sixteen trained (15 T 0.8 yr, V˙ O2peak = 54.7 T 6.2 mLIkgj1Iminj1, selfassessed Tanner stage range 2–4) and nine untrained (15 T 0.6 yr, V˙ O2peak = 43.1 T 5.2 mLIkgj1Iminj1, Tanner stage range 2–4) male adolescents performed two 6-min exercise transitions from a 3-min baseline of 10 W to a workload equivalent to 80% lactate threshold separated by a minimum of 1 h of passive rest. Oxygen uptake (breath-by-breath) and muscle deoxygenation (deoxyhemoglobin signal from near-infrared spectroscopy) were measured continuously throughout baseline and exercise transition. Results: The time constant of the fundamental phase of V˙ O2 kinetics was significantly faster in trained versus untrained subjects (trained: 22.3 T 7.2 s vs untrained:29.8 T 8.4 s, P = 0.03). In contrast, neither the time constant (trained: 9.7 T 2.9 s vs untrained: 10.1 T 3.4 s, P = 0.78) nor the mean response time (trained: 17.4 T 2.5 s vs untrained: 18.3 T 2.3 s, P = 0.39) of muscle deoxygenation kinetics differed with training status. Conclusions: The present data suggest that exercise training results in faster V˙ O2 kinetics in male adolescents, although inherent capabilities cannot be ruled out. Because muscle deoxygenation kinetics were unchanged, it is likely that faster V˙ O2 kinetics were due to adaptations to both the cardiovascular system and the peripheral musculature.

Aim: This cross-sectional study examined factors related to children's physical fitness and activity levels in Taiwan. Methods: A total of 331 Taiwanese children, aged 7 and 8, and their mothers participated in the study. Children performed physical fitness tests, recorded their physical activities during two weekdays and completed self-esteem questionnaires. Research assistants measured the children's body mass and stature. Mothers completed demographic, parenting style and physical activity questionnaires. Results: Attending urban school, lower body mass index (BMI), older age and better muscular endurance contributed to the variance in better aerobic capacity, and attending rural school and better aerobic capacity contributed to the variance in better muscular endurance in boys. Attending urban school, lower BMI and better athletic competence contributed to the variance in better aerobic capacity, and younger age, rural school and higher household income contributed to the variance in better flexibility in girls. Conclusion: Despite the limitations of the study, with many countries and regions, including Taiwan, now emphasizing the importance of improving physical fitness and activity in children, an intervention that is gender-, geographically, and developmentally appropriate can improve the likelihood of successful physical fitness and activity programmes.

Objective: Obesity has been proposed to negatively impact cardiac function in overweight (OW) individuals. The relationship between diastolic dysfunction and oxygen uptake (Vo2) kinetics is equivocal. This exploratory investigation evaluated the relationship between resting left ventricular function and Vo2 kinetics during cycle ergometry in OW and non-overweight (NO) children and adolescents. Research Methods and Procedures: Fourteen OW (>85 percentile for BMI for age and gender) children, 10 boys and 4 girls (age, 11.7 ± 1.9 years; body mass, 80.6 ± 45.5 kg) and 10 NO children (4 boys, 6 girls) volunteered to participate in the study (age, 12.5 ± 2.1 years; body mass, 45.8 ± 13.8 kg). Resting cardiovascular structure and function were assessed using spectral Doppler echocardiography. All subjects underwent two sub-maximal exercise stages on a cycle ergometer (3 minutes unloaded and 5 minutes at 50 W, both at a cadence of 50 rpm). Respiratory data were measured on a breath-by-breath basis at both workloads and the mean response time (MRT) was calculated. Results: Analysis of the MRT data demonstrated that there were no significant differences between OW and NO (OW, 52.6 ± 11.7 seconds vs. NO, 45.6 ± 7.4 seconds). Significant correlations (p < 0.05) were obtained between MRT Vo2 and echocardiographic-derived mitral valve inflow pressure half-time (r = 0.55) and between MRT Vo2, and mitral valve inflow deceleration time (r = 0.55). Discussion: The evidence from this research suggests a possible link between left ventricular diastolic function at rest and oxygen uptake kinetics during sub-maximal exercise in OW and NO children and adolescents.

Background and Purpose. Previous investigations have demonstrated that a regimen of high-intensity inspiratory muscle training (IMT) resulted in changes in ventilatory function and exercise capacity in patients with chronic lung disease, although the effect of high-intensity IMT in subjects who are healthy is yet to be determined. The purpose of this study, therefore, was to examine whether high-intensity IMT resulted in changes in ventilatory function and exercise capacity in subjects who were healthy. Subjects. Twenty subjects were randomly assigned to 2 groups. Methods. The training group completed an 8-week program of IMT set at 80% of maximal effort. The control group did not participate in any form of training. Baseline and posttraining measures of body composition, pulmonary function, inspiratory muscle function (including maximal and sustained maximal inspiratory pressures [MIP and SMIP]), relaxed and contracted diaphragm thickness and thickening ratio (Tdi.rel, Tdi.cont, and TR), and exercise capacity were determined. Results. The training group demonstrated significant increases in MIP, SMIP, Tdi.cont, TR, VC, total lung capacity, and exercise capacity compared with the control group, which demonstrated no change from baseline measurements at 8 weeks. Discussion and Conclusion. The findings of this study suggest that high-intensity IMT results in increased contracted diaphragm thickness and increased lung volumes and exercise capacity in people who are healthy. [Enright SJ, Unnithan VB, Heward C, et al. Effect of high-intensity inspiratory muscle training on lung volumes, diaphragm thickness, and exercise capacity in subjects who are healthy.

PURPOSE When metabolic rate during arm-cranking in the heat is equated between children and adolescents with cerebral palsy (CP) and matched controls (CON), there are no relevant intergroup differences in heat strain. The metabolic rate, however, is known to be higher in CP during treadmill walking. The purpose of this study was to determine if during treadmill walking in the heat, the higher oxygen uptake (VO2), and thus greater metabolic heat production in those with CP would result in greater heat strain compared with able-bodied, matched CON. METHODS Ten boys and girls (10.3-16.3 yr) with spastic CP and 10 individually matched (age, body size, biological maturity, gender, race) healthy CON performed 3 x 10-min treadmill walking bouts in 35 degrees C, 50% RH. Body mass, metabolic variables, heart rate (HR), body temperatures, and rating of perceived exertion (RPE) were periodically measured. Individuals within each CP-CON pair walked at the same speed and slope (0.9 +/- 0.4 m x s(-1), 3.3 +/- 0.6%). RESULTS Steady-state VO2 during walking, body temperatures, and HR were all higher in the CP group compared with CON. VO2 was on average 40% higher, rectal temperature was 0.4 degrees C (99% CI = 0.1-0.6 degrees C) higher and HR (during the final minute of each exercise bout) was 37 beats x min(-1) (99% CI = 19-56 beats x min(-1)) higher. There were no differences between the groups in sweating rate (as inferred from body mass changes corrected for fluid intake and output) or in RPE. CONCLUSION The subjects with CP demonstrated greater thermal strain than CON during treadmill walking where they require more metabolic energy and thus produce more metabolic heat than CON.

A paucity of literature exists with regard to research on nutrition for the pediatric athlete. This lack of research makes the development of specific nutritional recommendations for young athletes problematic. This issue is made difficult by the macro- and micronutrient intake required for growth and development in conjunction with that required for sports. Exogenous carbohydrate drinks could be considered for the young athlete engaged in both endurance exercise and high-intensity exercise. Monitoring of the energy intake during resistance training in the pediatric athlete needs to be considered, as there is evidence to suggest that energy deficits may occur. If decrements in exercise performance are noted, then serum ferritin and hemoglobin concentrations should be monitored, as nonanemic iron deficiency is prevalent in the pediatric athlete. The pediatric athlete exercising in the heat is susceptible to voluntary dehydration and evidence exists to suggest that a carbohydrate-electrolyte drink will abolish this phenomenon.

La posibilidad de que la actividad fisica pueda poner en peligro la vida del deportista existe, pero no siempre se tiene en cuenta. La muerte en la practica deportiva o el riesgo de un suceso cercano a la misma es bajo, y ambos se asocian habitualmente a procesos de origen cardiovascular. En el presente articulo se realiza una revision de las enfermedades respiratorias y alergicas mas frecuentes —asma, anafilaxia, embolismo pulmonar, neumotorax espontaneo—, dignas de una atencion y una formacion seria y dirigida para permitir una practica con el maximo de seguridad. Se propone acoger el concepto de enfermedad de riesgo vital en el deporte para concienciar a los especialistas en identificar esas enfermedades, que de acuerdo con este concepto ayuden a establecer unas indicaciones y guias utiles para los portadores de esas enfermedades ante unas condiciones deportivas determinadas para asegurar un deporte sano y saludable.

Purpose The purpose of this study was to compare cardiac physiological and dimensional responses to exercise in highly trained young male cyclists (mean age 13.7 +/- 1.0 yr) with those of nontrained boys. Methods Ventricular systolic and diastolic dimensions were measured by two-dimensional echocardiography, and stroke volume was estimated by Doppler echocardiography during a progressive maximal upright cycle test. Results At rest, the cyclists demonstrated larger left ventricular dimensions relative to body size than the nonathletes. Maximal stroke index and cardiac index were significantly greater in the cyclists. The pattern of stroke volume response to exercise was similar in the two groups, with an early rise and then plateau to exhaustion. Left ventricular diastolic dimension increased slightly at onset of exercise and then gradually declined as workload increased in both groups. Conclusion Factors responsible for the greater maximal stroke volume in young endurance athletes involve those variables that contribute to resting left ventricular diastolic filling (preload).

Little evidence exists with regard to changes in cardiac strain that occur during submaximal exercise in young males. The aims of the study were to evaluate the changes that occur in longitudinal (L), radial (R) and endocardial circumferential (EC) strain during submaximal upright cycle ergometry and to examine the test-retest reproducibility of these measurements. Fourteen recreationally active, adolescent (age: 17.9 ± 0.7 years), males volunteered for the study. All subjects underwent an incremental (40W) submaximal cycle ergometer test. L, R, and EC strain values were obtained using speckle tracking, from two-dimensional B-mode images of the left ventricle (LV) during rest and the initial stages of submaximal exercise (40W and 80W). The average of 6 LV segments was used to determine both peak wall deformation (%) and the time to peak deformation (ms). There was a statistically (P

The effects of a short, high-intensity bout of exercise on cardiac systolic and diastolic function are not well understood in adolescent athletes. Consequently, the aims of the study were to evaluate global left ventricular (LV) systolic and diastolic function, as well as segmental wall motion responses (cardiac strain), prior to as well as 45 and 225 min following a simulated 5 km cross-country race. Twenty trained, adolescent males (age: 15.2 ± 0.7 years) volunteered for exercise testing. LV fractional shortening and the ratio of early (E) and late (A) peak flow velocities reflected global systolic and diastolic function, respectively. Peak longitudinal mitral annular septal tissue velocities were also determined during systole and diastole. Longitudinal strain (e) and strain rates were determined across the LV. LV fractional shortening was significantly (P < 0.05) higher at 225 min post-race (37.6 ± 5.8%) compared to pre-race (34.5 ± 4.7%) and 45 min post-race (34.9 ± 5.4 %). This difference was abolished after adjusting for post-race heart rates. There was a significant (P < 0.05) decrease in the E:A ratio at both 45 min (2.04 ± 0.57) and 225 min post-race (2.20 ± 0.66) compared to the pre-race value (2.80 ± 0.68). When these data were adjusted for post-race heart rates, these pre-post-race differences in E:A ratio were abolished. There were no significant alterations in either tissue Doppler velocities or longitudinal e. The evidence suggests that a 5 km race does not lead to any significant post-exercise attenuation in global or regional LV systolic and diastolic function in trained adolescents.

Assessment of myocardial contractile function during exercise is important in gaining an understanding of the normal mechanics of the cardiovascular responses to exercise stress. Such insights are important in identifying determinants of cardiovascular fitness in athletes as well as assessing patients with heart disease. While obtaining such measurements in the past has been challenging, recent echocardiographic developments offer promise of providing new insights into the nature and magnitude of inotropic changes during exercise. This review provides a state-of-the-art overview of these technologies in light of the current understanding of the role of myocardial contractile function in response to a bout of progressive dynamic exercise.

A major movement related limitation for children with spastic cerebral palsy (CP) is the compromised gait pattern, which may explain their excessive energy cost of locomotion. The aims of this study were to determine differences in the O2 cost of locomotion between children with CP (7 males, 2 females; 12.7 +/- 2.8 yr) and able-bodied controls (7 male, 1 female; 13.6 +/- 2.1 yr) and to assess the contribution that cocontraction of agonist and antagonist muscles had upon the elevated O2 cost seen in children with CP versus able-bodied controls. The treadmill submaximal walking protocol consisted of 2 x 4 min intermittent stages at 3 km.h-1 and 90% of the predetermined fastest walking speed (FWS) at 0% grade. Electromyographic data were collected during the final minute of each bout from vastus lateralis and hamstrings (thigh) and tibialis anterior and soleus (lower leg). Significant (P0.05) differences were noted at 3 km.h-1 for mass-relative VO2. (CP: 16.6 +/- 6.5 vs control: 10.2 +/- 1.2 ml.kg-1.min-1), % VO2max (CP: 53.5 +/- 26.0 vs22.5 +/- 4.93) and heart rate (CP: 143 +/- 41 vs91 +/- 14 beats.min-1). Thigh and lower leg muscle cocontraction accounted for 51.4% and 42.8%, respectively, of the variability in VO2 for the subjects with CP at 3 km.h-1. These results suggest that cocontraction is a major factor responsible for the higher energy cost of walking seen in children with CP.

Aim. To evaluate the effects of aquatic (AQ) compared to a land-based (LB) intervention programs on metabolic cost of walking (MCW), gross motor function and locomotor performance in children with cerebral palsy (CP). Methods. Eleven children with spastic diplegic CP completed this study, six in the AQ (5.2 ± 1.45 yrs) and five in the LB group (4.1 ± 1.33 yrs). MCW derived from Oxygen uptake (VO2) measured with a Cosmed K4 device and walking speed at steady state. Additional measures included the 10-m test, Gross Motor Function Measure (GMFM), and Pediatric Evaluation Developmental Inventory (PEDI). Non-parametric statistics were used to analyze change in each group. Results. The AQ group significantly decreased MCW (Z=−2.2; P<.05) and increased steady state walking speed (Z=−2.2; P<.05). Both groups significantly increased 10-m walking speed (Z=−2.2; P<.03, and Z=−2.02; P<.05, resp.). The LB group exhibited moderate to large effect sizes in 10-m self-selected and fast walking speeds (Cohen's d=1.07 and 0.73, resp.). Conclusion. Our findings suggest that Both AQ and LB programs were effective in improving 10-m speed, while the AQ training also improved the MCW of walking at steady state in children with spastic diplegic CP.

Purpose: The extent that enhanced ventricular function contributes to superior aerobic fitness of trained athletes is unclear. This study compared cardiovascular responses to progressive cycle exercise in 12 adolescent soccer players and 10 untrained boys with assessment of ventricular inotropic and relaxation properties by Doppler ultrasound techniques. Methods: Resting cardiac dimensions were measured by M-mode echocardiography. Stroke volume was estimated by the Doppler technique, and systolic function by peak aortic flow velocity and ejection flow rate. Diastolic transmitral pressure gradient was assessed by pulse wave peak E-wave velocity, ventricular relaxation properties by tissue Doppler imaging (E' velocity, adjusted for ventricular size), and ventricular filling pressure by E/E' ratio. Results: Size-adjusted cardiac dimensions were significantly greater in the athletes. Peak V[spacing dot above]O2 values for the athletes and nonathletes were 57.4 +/- 4.8 and 44.4 +/- 6.6 mL[middle dot]kg-1[middle dot]min-1, respectively. Maximal cardiac index and stroke index were greater in the athletes (11.10+/- 1.52 vs 9.02 +/- 2.05 L[middle dot]min-1[middle dot]m-2; 59 +/- 8 vs 46 +/- 10 mL[middle dot]m-2). Athletes and nonathletes demonstrated similar maximal peak aortic velocity (231 +/- 20 and 208 +/- 45 cm[middle dot]s-1, respectively) and ejection rate (13.3 +/- 1.0 and 12.5 +/- 2.8 mL[middle dot]s-1[middle dot]cm-2 x 10-2, respectively). No significant group differences were observed in Emax (155 +/- 17 and 149 +/- 23 cm[middle dot]s-1 for athletes and nonathletes, respectively), adjusted E'max (5.9 +/- 1.2 and 5.8 +/- 1.2 cm[middle dot]s-1[middle dot]mm-1 for athletes and nonathletes, respectively), and E/E'max (265 +/- 40 and 262 +/- 56 for athletes and nonathletes, respectively). Conclusions: This study revealed no differences between young trained athletes and nonathletes in myocardial functional responses to progressive exercise, implying that greater aerobic fitness in these athletes reflected volume expansion of the cardiovascular system without contribution of enhanced systolic or diastolic ventricular function. Such findings should be considered limited to the context of young athletes with limited duration of athletic training.

The purpose of the study was to determine the degree to which scores of a modified version of the 'Timed Get Up and Go' test (TGUG) were associated with other measures of functional performance. Thirty-seven community-dwelling older women (72.3 +/- 5.5 years) volunteered to participate. Subjects were assessed when performing the modified TGUG test. Correlations between the performance-oriented mobility assessment (POMA), single-leg balance, five chair rises, fast and normal gait speed, knee extension and flexion strength, and the modified TGUG were conducted. Total time to perform the modified TGUG test was significantly correlated with normal and fast gait speed (p < 0.05). The Pearson correlation coefficients were -0.841 and -0.748, respectively. The time needed to perform several tasks of the modified TGUG test significantly correlated with five chair rises, and with right knee extensor strength (p < 0.05). Points obtained in the assessment questionnaire correlated significantly to points obtained in the POMA scale (p < 0.05). The Pearson correlation coefficient was 0.795. Based on the strength of the correlations obtained between components of the modified TGUG and the comparison tests, concurrent, criterion validity of the modified TGUG has been established. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

The purpose of this study was to assess the sensitivity of a modified version of the 'Timed Get Up and Go' (TGUG) test in predicting fall risk in elderly individuals, using both a quantitative and qualitative approach in individuals older than 65 years. Ten subjects (83.4 +/- 4.5 years) undertook the test twice. To assess inter-rater reliability, three investigators timed the two trials using a stopwatch (quantitative). The reproducibility of a qualitative evaluation of the trials was accomplished by the completion of an assessment questionnaire (AQ) at each trial by three investigators. To assess the agreement between the three investigators, the coefficients of reliability (CR), intra-class correlation coefficients (ICC) and limits of agreement were determined for the total time to do the test (TT). The weighted Kappa K of Cohen and ICC was calculated for the AQ. Inter-group comparison: 60 subjects (74.2 +/- 4.9 years) were divided equally into four groups: (1) sedentary with previous history of falls, (2) sedentary without history of falls, (3) active with history of falls, and (4) active without history of falls. All of them undertook the modified TGUG test once. One investigator undertook the timing and completed the AQ. CR values for the TT were above 98% and with ICC of TT = 0.999. The differences in TT between the three investigators' measures ranged from 0.19-0.55 s S. D. of the mean difference. Weighted Kappa K of Cohen ranged 0.835-0.976, with ICC of AQ = 0.954. Inter-group comparison study. Significant differences (p < 0.05) were noted between the mean score of TT of Group 4 and the rest of the groups, and between Groups 2 and 1. Significant differences (p < 0.05) were noted between the mean score of points obtained in the AQ of Group 1 and the rest of the groups. The modified version of the TGUG test demonstrated good sensitivity for detecting fall risk in elderly individuals, and good inter-tester reliability from both a quantitative and qualitative perspective. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Introduction: Persons with mental retardation (MR), particularly individuals with Down syndrome (DS), have been found to have attenuated peak exercise responses in previous research. However, it is unknown if the pattern of age-associated changes in HR or aerobic capacity (V[spacing dot above]O2peak) is similar to individuals without disabilities. Purpose: To investigate age-related changes in aerobic capacity in persons withMR, with and without DS, using a retrospective analysis. Methods: Data were collected in university research laboratories, using 180 persons with MR without DS, 133 persons with MR with DS, and 322 persons without disabilities in four age categories: 9-15, 16-21, 22-29, and 30-45 yr. Subjects underwent treadmill testing with peak HR and V[spacing dot above]O2peak measurements. Results: Relative V[spacing dot above]O2peak was lowest for persons with DS across all age groups. V[spacing dot above]O2peak did not change after 16 yr in the individuals with DS, whereas the other groups exhibited a slight decline (~10 mL[middle dot]kg-1[middle dot]min-1) with age. Peak HR was overall different between all three groups (P < 0.001), and the youngest age group had the highest peak HR versus the other three age groups (P < 0.0001). Conclusions: Persons with MR without DS exhibit similar age-related changes in V[spacing dot above]O2peak and peak HR as individuals without disabilities. Similar age-related changes were also observed for peak HR in individuals with DS, despite overall lower levels. However, relative V[spacing dot above]O2peak did not decline with age in persons with DS, suggesting that aerobic capacity exhibits a different age-related response in individuals with DS.

Purpose: The aim of this study was to evaluate the effectiveness of a strength and aerobic interval training program on arm-cranking economy, aerobic capacity, and gross motor function in children and adolescents with spastic diplegic cerebral palsy (CP). Methods: Seven subjects (five females, two males; mean age 15.9, range 14-18 yr) participated in a 12-wk aerobic interval and strength training program, three times per week, 70 min per session. The aerobic interval training required the subjects to perform 60-m uphill walking repetitions. Six individuals (four females, two males; mean age 15.7, range 14-17 yr) who did not receive the training program served as controls. Pre- and postexercise tests were performed to assess changes in arm-cranking economy, aerobic capacity, and gross motor function. Results: The results demonstrated significant (P < 0.05) reductions in the oxygen cost of arm cranking (mean +/- SD: pre: 13.2 +/- 3.22 mL[middle dot]kg-1[middle dot]min-1, post: 12.7 +/- 3.38 mL[middle dot]kg-1[middle dot]min-1) and %V[spacing dot above]O2peak (pre: 75.8 +/- 3.55%, post: 61.8 +/- 7.47%) in the training group. Significant (P < 0.05) increases in aerobic capacity (pre: 17.5 +/- 4.45 mL[middle dot]kg-1[middle dot]min-1, post: 20.8 +/- 5.93 mL[middle dot]kg-1[middle dot]min-1) were also noted for the training group. Significant (P < 0.05) improvements in gross motor function measures were also noted in the training group (pre: 30.35%, post: 33.85%). Conclusion: These findings demonstrate that the application of a 12-wk strength and aerobic interval training program reduced the oxygen cost of arm cranking, improved aerobic capacity, and improved gross motor function in children and adolescents with CP

To evaluate the effect of maturity status on the autonomic nervous system at rest and recovery after short-term, high-intensity exercise in adolescents.A biological maturity age was estimated in 27 males by calculating the years from peak height velocity (PHV) using a multiple regression equation. Subjects were divided into two groups: pre-PHV (years from PHV0.49), N = 14, mean age = 12.29 +/- 0.91 yr; post-PHV (years from PHV0.5, N = 13, mean age = 15.12 +/-0.76 yr). HR variability was used to evaluate autonomic function. ECG tracings were collected during 5 min at rest and recovery after a Wingate test and were analyzed in the frequency domain (low-frequency (LF), high-frequency (HF), LF/HF, total power (TP)). Data are presented as natural logarithms (LN).Changes in HR from HR(peak) during exercise to HR measured at minute 4 after exercise ([DELTA]HR4) were significantly greater in the pre-PHV group (84.31 +/-17.58 bpm) compared with the post-PHV group (69.42 +/-17.63 bpm). There were no significant differences in resting HR variability between pre- and post-PHV groups (P0.05). Significant group x time interactions were found for LF(LN) (ms(2)) and TP(LN) (ms(2)) measured during recovery (P0.05). Post hoc tests showed that the pre-PHV group had significantly higher postexercise LF(LN) (5.02 +/- 0.97 vs 4.19 +/- 0.79) and TP(LN) (6.36 +/- 1.02 vs 5.62 +/- 0.65) compared with the post-PHV group. When postexercise LF(LN) (ms(2)) was normalized for TP(LN) (ms(2)), there were no significant differences between groups (P0.05).The pre-PHV group had higher total HR variability than the post-PHV group after a Wingate test, suggesting that maturity status significantly affects total HR variability during recovery after high-intensity exercise.

Previous investigations have demonstrated that a regimen of high-intensity inspiratory muscle training (IMT) resulted in changes in ventilatory function and exercise capacity in patients with chronic lung disease, although the effect of high-intensity IMT in subjects who are healthy is yet to be determined. The purpose of this study, therefore, was to examine whether high-intensity IMT resulted in changes in ventilatory function and exercise capacity in subjects who were healthy.Twenty subjects were randomly assigned to 2 groups.The training group completed an 8-week program of IMT set at 80% of maximal effort. The control group did not participate in any form of training. Baseline and posttraining measures of body composition, pulmonary function, inspiratory muscle function (including maximal and sustained maximal inspiratory pressures [MIP and SMIP]), relaxed and contracted diaphragm thickness and thickening ratio (Tdi.rel, Tdi.cont, and TR), and exercise capacity were determined.The training group demonstrated significant increases in MIP, SMIP, Tdi.cont, TR, VC, total lung capacity, and exercise capacity compared with the control group, which demonstrated no change from baseline measurements at 8 weeks.The findings of this study suggest that high-intensity IMT results in increased contracted diaphragm thickness and increased lung volumes and exercise capacity in people who are healthy.

Objectives:A matched case-control study was carried out to evaluate biological risk indicators for recurrent non-specific low back pain in adolescents.Methods:Adolescents with recurrent non-specific low back pain (symptomatic; n = 28; mean (SD) age 14.9 (0.7) years) and matched controls (asymptomatic; n = 28; age 14.9 (0.7) years) with no history of non-specific low back pain participated. Measures of stature, mass, sitting height, sexual maturity (Tanner self assessment), lateral flexion of the spine, lumbar sagittal plane mobility (modified Schöber), hip range of motion (Leighton flexometer), back and hamstring flexibility (sit and reach), and trunk muscle endurance (number of sit ups) were performed using standardised procedures with established reliability. Backward stepwise logistic regression analysis was performed, with the presence/absence of recurrent low back pain as the dependent variable and the biological measures as the independent variables.Results:Hip range of motion, trunk muscle endurance, lumbar sagittal plane mobility, and lateral flexion of the spine were identified as significant risk indicators of recurrent low back pain (pConclusions:Hip range of motion, abdominal muscle endurance, lumbar flexibility, and lateral flexion of the spine were risk indicators for recurrent non-specific low back pain in a group of adolescents. These risk indicators identify the potential for exercise as a primary or secondary prevention method.

The aim of this investigation was to provide evidence of the prevalence and consequences of recurrent low-back pain in children from Northwest England. A cross-sectional survey was conducted involving a standardized questionnaire with established reliability and validity. A cross-sectional sample of 500 boys (n = 249) and girls (n = 251) aged between 10 and 16 years participated in the study. Average lifetime prevalence of low-back pain was 40.2% [95% confidence interval (CI) = 38.7‐41.6]. Most cases of low-back pain were acute episodes that did not lead to disabling consequences. In contrast, 13.1% (95% CI = 12.5‐ 13.7) experienced recurrent low-back pain that led to disabling consequences; 23.1% visited a medical practitioner, 30.8% experienced loss of physical activity/sports and 26.2% had been absent from school because of low-back pain. Recurrent low-back pain was particularly evident during late adolescence where one in five children were cases. The health education implications of low-back pain in children are discussed. It was concluded that low-back pain is a common complaint during childhood, although most cases are acute episodes that represent little health consequence. In contrast, some children experience recurrent low-back pain that can lead to disabling consequences. Future research should focus on recurrent lowback pain cases since they often led to disabling consequences.

PURPOSE In response to passive heating, adults with hemispheric brain infarction demonstrate lower skin temperatures (Tsk) and higher sweating rates (SR) on the affected side. It is unknown whether children with similar conditions demonstrate a similar response and whether this response is advantageous to defending body temperature during exercise in the heat. The purpose of this study was to determine whether children with spastic cerebral palsy (CP) demonstrate less thermal strain than healthy peers during short (10 min each) bouts of arm cranking, a mode of exercise where metabolic rate can be matched between the two groups. METHODS Eleven young people (8.3-18.3 yr) with spastic CP and 11 individually matched (body size, age, and maturity) healthy controls (CON) performed 3 x 10-min arm-cranking bouts (40 rpm) in 35 degrees C, 50% RH. Body mass, metabolic and heart rate (HR) responses, and body temperatures were periodically measured. Individuals within each CP-CON pair worked at the same intensity (0.55 +/- 0.18 W.kg-1 body mass). Data were analyzed using a repeated measures ANOVA (alpha = 0.05). RESULTS Subjects with CP showed no difference from CON in metabolic and HR responses, or SR (as inferred from body mass changes corrected for fluid intake and output). There were also no differences between the groups in the rectal temperature change from room temperature (21-23 degrees C). The increase in Tsk from room temperature, however, was slightly (0.6 degrees C) but significantly lower (P < 0.0001; 95% CI = 0.5-0.7 degrees C) in the subjects with CP compared with CON. CONCLUSION Subjects with CP demonstrate thermal strain responses similar to CON during upper-body exercise at relatively low intensities for short duration in a warm climate.

Liver transplantation is accepted as the standard management for end-stage liver disease in children. Pediatric heart and heart-lung transplant recipients have shown significantly diminished exercise capacities compared with age-matched, able-bodied, control subjects. The primary aim of this study is to compare the fitness levels of a group of pediatric liver transplant (LT) recipients (LT group, 20 boys, 9 girls; age, 8.9 ± 4.8 years; 56 ± 35 months posttransplantation) with a group of able-bodied control subjects (22 boys, 12 girls; age, 8.4 ± 3.8 years). The secondary aim is to compare the performance of the LT group against the Fitnessgram criterion standards. We assessed muscular endurance by means of a partial curl-up, flexibility by means of the back-saver sit and reach, and cardiorespiratory fitness by means of the progressive aerobic cardiovascular endurance run (PACER). The only significant (P < .05) difference between the 2 groups was the number of shuttles run in the PACER (control, 16.8 ± 9.8 v LT, 11.5 ± 8.4 shuttles). Other differences between the 2 groups were not significant. With regard to satisfying the Fitnessgram criterion standards, only 35% of the LT group achieved the standards for the partial curl-up, 88% of the LT group achieved the criterion standards for flexibility, and 0% achieved the standards for the PACER. These results indicate that the LT group has diminished exercise capacity. The origins of exercise limitations deserve further investigation. (Liver Transpl 2001;7:206-212.)