João Brito

Activity profile and physiological response to football training for untrained males and females, elderly and youngsters: influence of the number of players.

The present study examined the activity profile, heart rate and metabolic response of small‐sided football games for untrained males (UM, n=26) and females (UF, n=21) and investigated the influence of the number of players (UM: 1v1, 3v3, 7v7; UF: 2v2, 4v4 and 7v7). Moreover, heart rate response to small‐sided games was studied for children aged 9 and 12 years (C9+C12, n=75), as well as homeless (HM, n=15), middle‐aged (MM, n=9) and elderly (EM, n=11) men. During 7v7, muscle glycogen decreased more for UM than UF (28 ± 6 vs 11 ± 5%; P<0.05) and lactate increased more (18.4 ± 3.6 vs 10.8 ± 2.1 mmol kg−1 d.w.; P<0.05). For UM, glycogen decreased in all fiber types and blood lactate, glucose and plasma FFA was elevated (P<0.05). The mean heart rate (HRmean) and time >90% of HRmax ranged from 147 ± 4 (EM) to 162 ± 2 (UM) b.p.m. and 10.8 ± 1.5 (UF) to 47.8 ± 5.8% (EM). Time >90% of HRmax (UM: 16–17%; UF: 8–13%) and time spent with high speed running (4.1–5.1%) was similar for training with 2–14 players, but more high‐intensity runs were performed with few players (UM 1v1: 140 ± 17; UM 7v7: 97 ± 5; P<0.05): Small‐sided games were shown to elucidate high heart rates for all player groups, independently of age, sex, social background and number of players, and a high number of intense actions both for men and women. Thus, small‐sided football games appear to have the potential to create physiological adaptations and improve performance with regular training for a variety of study groups.

Performance enhancements and muscular adaptations of a 16‐week recreational football intervention for untrained women

The present study investigated the performance effects and physiological adaptations over 16 weeks of recreational football training and continuous running for healthy untrained premenopausal women in comparison with an inactive control group [Football group (FG): n=21; running group (RG): n=18; CO: n=14]. Two weekly 1‐h training sessions were performed in FG and RG. After 4 and 16 weeks of training VO2max was elevated (P<0.05) by 7% and 15%, respectively, in FG, and by 6% and 10%, respectively, in RG. After 16 weeks, Yo‐Yo intermittent endurance level 2 performance was 33% and 19% better (P<0.05) for FG and 29% and 21% better (P<0.05) for RG than after 4 and 0 weeks, respectively. Peak sprinting speed was 12% higher (21.0 ± 0.6 vs 18.8 ± 0.7 km/h; P<0.05) for FG after the training period, whereas no difference was observed for RG. After 4 weeks citrate synthase (CS) and 3‐hydroxyacyl‐CoA dehydrogenase (HAD) activity was 9% and 8%, respectively, higher (P<0.05) than before training in FG with no further changes during the last 12 weeks. In RG, CS increased (P<0.05) by 12% after 4 weeks and no significant increase was observed for HAD. In FG, the number of capillaries per fiber was 18% higher (P<0.05) after 16 weeks (2.44 ± 0.15 vs 2.07 ± 0.05 cap/fiber), with no significant difference for RG. No differences were observed between 0 and 16 weeks for CO. In conclusion, recreational womens football leads to significant increases in VO2max, performance and muscular adaptations throughout a 16‐week training period. Thus, football can be used as an activity to elevate the physical capacity of untrained women.

Anthropometric Characteristics, Physical Fitness and Technical Performance of Under-19 Soccer Players by Competitive Level and Field Position

Anthropometric characteristics, physical fitness and technical skills of under-19 (U19) soccer players were compared by competitive level (elite, n=95; non-elite, n=85) and playing position (goalkeeper, central defender, fullback, midfield, forward). Fitness tests included 5- and 30-m sprints, agility, squat jump (SJ) and countermovement jump (CMJ), strength and Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2). Soccer-specific skills included ball control and dribbling. Independent of position, elite players presented more hours of training per year than non-elite players (d>1.2). Stature and body mass discriminated elite from non-elite players among goalkeepers and central defenders (d>0.6). Major differences were noted between elite and non-elite goalkeepers for SJ, CMJ, Yo-Yo IE2, and ball control (d>1.2). Elite central defenders performed better than their non-elite counterparts in SJ and ball control tests (d>1.2). Elite players presented better agility and Yo-Yo IE2 performances than non-elite players within all positional roles (d>0.6). In conclusion, U19 players differed in anthropometric characteristics, physical fitness and technical skills by competitive level within field positions.

The association of environmental heat stress with performance: analysis of the 2014 FIFA World Cup Brazil

Objective The 2014 FIFA World Cup Brazil included 64 matches in temperate to tropical environmental conditions. We analysed performance data in relation to the environmental conditions to identify potential association. Methods Wet-bulb globe temperature (WBGT) parameters were obtained at the centre of the field 1 h before the start of play. Environmental stress was estimated (low, moderate and high) for each match using WBGT and relative humidity. Various physical and technical performance indices were recorded during each match (average of both teams). Results Over the 64 matches, 28 were played under low, 20 under moderate and 16 under high environmental stress. There was no difference in actual playing time (p=0.517), total distance covered (p=0.491), number of goals scored (p=0.485) and number of cards (p=0.618) between the matches played under different environmental stress categories. The number of sprints was lower in high than in moderate or low environmental stress (−10%, p<0.05) but peak speed was unaffected. The distance covered at high intensity was also lower under high (24.8±2.8 m/min/player) than low environmental stress (26.9±2.3 m/min/player, p=0.02). Number of passes was not different but the rate of successful passes was higher under high (76.8±4.4%) than low (73.6±10.8%) environmental stress (p=0.031). Conclusions Top-level players seem to modulate their activity pattern during matches in a hot and humid environment (ie, less high-intensity but more low-intensity running and successful passes) to preserve the global match characteristics (ie, similar actual playing time, total distance covered, peak running speed and goals scored).

Physical match performance of youth football players in relation to physical capacity

Abstract The aims of the study were to (1) analyse the activity profile of youth football players during competitive matches, and (2) examine the relationship between physical match performance and intermittent exercise performance as well as . Thirty youth male football players, aged 14–17 years, carried out a laboratory treadmill test for determination of as well as the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) and Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) tests. Time–motion analysis and heart rate (HR) recordings were performed during two competitive matches per player. Distance covered during the match was 6311±948 (range: 4435–8098) m, of which 12% were high-intensity activities (HIA; 759±437 [374–2062] m), and 5% was backwards running (309±205 [12–776] m). Mean match HR was 168±12 (140–187) bpm, corresponding to 85% (69–91) of maximum HR. The total distance covered in the last 13.3-min period of the match was 40%, 26% and 17% lower than in the first, second and fourth 13.3-min periods of the match, respectively (P<0.05). The distance covered in backwards running decreased by 31% and 37% from the first to the last 13.3-min periods of the first and second half, respectively (P<0.05). The Yo-Yo IR1 was significantly associated with the time spent with sprinting during the match (r=0.63; P=0.002) and during the last 13.3-min period (r=0.63; P=0.022). Both Yo-Yo IR1 and Yo-Yo IE2 were correlated with the time spent with match HIA (r=0.56 and r=0.57, respectively; P<0.05). No significant relationship was observed between and match time–motion variables (r=−0.13–0.25; P>0.05) or Yo-Yo test performances (r=0.09–0.26; P>0.05). In conclusion, youth football players have a high heart-rate loading during match play and a decreased running performance towards the end of the game. The intermittent exercise capacity, as determined in the Yo-Yo IR1 test, appears to be a valid indicator of high-intensity exercise performance in youth matches.

Injuries in Portuguese Youth Soccer Players During Training and Match Play

CONTEXT Epidemiologic information on the incidence of youth soccer injuries in southern Europe is limited. OBJECTIVE To compare the incidence, type, location, and severity of injuries sustained by male subelite youth soccer players over the 2008-2009 season. DESIGN Descriptive epidemiology study. SETTING Twenty-eight Portuguese male youth soccer teams. PATIENTS OR OTHER PARTICIPANTS A total of 674 youth male subelite soccer players in 4 age groups: 179 U-13 (age range, 11-12 years), 169 U-15 (age range, 13-14 years), 165 U-17 (age range, 15-16 years), and 161 U-19 (age range, 17-18 years). MAIN OUTCOME MEASURE(S) Injuries that led to participation time missed from training and match play prospectively reported by medical or coaching staff of the clubs. RESULTS In total, 199 injuries reported in 191 players accounted for 14.6 ± 13.0 days of absence from practice. The incidence was 1.2 injuries per 1000 hours of exposure to soccer (95% confidence interval [CI] = 0.8, 1.6), with a 4.2-fold higher incidence during match play (4.7 injuries per 1000 hours of exposure; 95% CI = 3.0, 6.5) than during training (0.9 injuries per 1000 hours of exposure; 95% CI = 0.6, 1.3) (F₁,₆₇₃ = 17.592, P < .001). The overall incidence of injury did not increase with age (F₁,₆₇₃ = 1.299,P = .30), and the incidence of injury during matches (F₁,₆₇₃ = 2.037, P = .14) and training (F₁,₆₇₃ = 0.927, P = .44) did not differ among age groups. Collisions accounted for 57% (n = 113) of all injuries, but participation time missed due to traumatic injury did not differ among age groups (F₃,₁₁₀ = 1.044, P = .38). Most injuries (86%, n = 172) involved the lower extremity. The thigh was the most affected region (30%, n = 60) in all age groups. Muscle strains were the most common injuries among the U-19 (34%, n = 26), U-17 (30%, n = 17), and U-15 (34%, n = 14) age groups, whereas contusions and tendon injuries were the most common injuries in U-13 players (both 32%, n = 8). The relative risk of injury slightly increased with the age of the competitors. CONCLUSIONS The higher incidence of injury during matches than training highlights the need for education and prevention programs in youth soccer. These programs should focus on coach education aimed at improving skills, techniques, and fair play during competitions with the goal of reducing injuries.

Muscle strength and soccer practice as major determinants of bone mineral density in adolescents

OBJECTIVES To analyse the relationship between isokinetic strength of the lower limb muscles and bone mineral density and content (BMD, BMC) of adolescent male soccer players and age-matched controls not involved in sport (12-15 years). METHODS A random sample of 151 young males was divided into soccer players (SG; n=117) and control subjects (CG; n=34). Peak torque of knee extensors (PTE) and flexors (PTF) was measured during isokinetic knee joint movement (90°/s) of the dominant and non-dominant lower limbs. BMD and BMC of the whole-body, lumbar spine, dominant/non-dominant lower limb were determined by dual-energy X-ray absorptiometry. Physical activity was monitored with accelerometers during 5 days. Estimated maturity offset was used as an indicator of biological maturity status. RESULTS Whole-body BMD (1.03±0.01 vs. 0.98±0.01 g/cm2, P=0.003) and dominant (1.09±0.01 vs. 1.02±0.01 g/cm2, P<0.001) and non-dominant (1.09±0.01 vs. 1.01±0.01 g/cm2, P<0.001) lower limb BMD was greater in SG compared to CG. No significant differences were found for BMC. Compared to CG, SG performed better in the YY-IE2 test (780±40 vs. 625±31 m), exhibited higher PTE (dominant limb: 155.2±30.3 vs. 123.4±37.0N m; non-dominant limb: 156.2±36.1 vs. 120.4±41.1 N m) and PTF muscles (dominant limb: 79.0±25.3 vs. 57.1±25.3 Nm; non-dominant limb: 73.3±20.7 vs. 57.0±24.2N m). Moreover, the PTE, soccer participation and maturity status were positively associated with the BMD at all body sites (r2=0.57-0.73, P<0.05). CONCLUSIONS Muscle strength of knee extensors is associated with BMD and BMC at all body sites. Muscle-skeletal structures respond positively to the weight-bearing and impact-loading imposed by soccer practice. Soccer seemed to be a multilateral balanced sport activity.

The influence of the playing surface on the exercise intensity of small-sided recreational soccer games.

This study aimed to analyze the influence of the playing surface on movement pattern, physical loading, perceived exertion, and fatigue development during small-sided recreational soccer games. Time-motion, heart rate, blood lactate, and perceived exertion were measured for 16 recreational players aged 22 (range: 19-35) yrs. During 5-a-side soccer games on 3 different field surfaces: sand, artificial turf, and asphalt. Jump and sprint tests were performed prior to and after each game. Total distance covered was higher on asphalt and turf than on sand (3.89±0.04 and 3.73±0.12 vs. 2.59±0.21 km; p<.01), and the number of high-intensity runs was higher on asphalt than on turf (55±3 vs. 43±3; p<.05), but not sand (46±6). Mean heart rate (means±SEM, 160±3 vs. 171±1 b.p.m.) and time>90% HR(max) (20.8±5.1% vs. 44.1±5.0%) were lower (p<.05) on asphalt than on turf, with intermediate values for sand. Blood lactate was lower on asphalt than on sand (2.8±0.3 vs. 4.7±0.6 mmolL(-1); p<.05). Perceived exertion was lower on asphalt than on turf and sand (VAS 0-100: 52±3 vs. 72±3 and 72±3; p<.01). After the game, squat and countermovement jump performances were lower (4.9-8.1%, and 1.9-6.4%, respectively; p<.001) for all field surfaces, but no changes were observed in 5- and 30-m sprint performance. Small-sided recreational soccer games elicit high heart rates, multiple intense actions, and decreased jump performance for all the investigated playing surfaces, suggesting that multiple fitness and health benefits can be achieved through soccer on sand, artificial turf and asphalt. Nonetheless, locomotor activities, heart rate, blood lactate levels, and perceived exertion differ between surfaces.

Cardiovascular effects of 3 months of football training in overweight children examined by comprehensive echocardiography: a pilot study

Abstract We examined effects of a 3-month football training programme in overweight children using comprehensive echocardiography and peripheral arterial tonometry. Twenty preadolescent overweight children (17 boys, 3 girls aged 8–12 yrs; body mass index [BMI] ≥ 85th percentile) participated in a structured 3-month football training programme, consisting of 4 weekly 60–90 min sessions with mean heart rate (HR) > 80% of HRmax (football group, FG). A parallel control group (CG) included 11 children (7 boys, 4 girls) of equivalent age from an obesity clinic. After 3 months, systolic blood pressure was unchanged in FG, but had increased in CG (112 [s 6] vs. 122 [10] mmHg, P = 0.02). FG demonstrated increased left ventricular (LV) posterior wall diameter (0.60 [0.07] vs. 0.68 [0.10] cm, P < 0.001) and an improved right ventricular systolic function determined by tricuspid annular plane systolic excursion (TAPSE, 2.01 [0.29] vs. 2.27 [0.28] cm, P = 0.003). Measures of LV systolic function showed only discrete alterations and two-dimensional (2D) global strain was not changed. After 3 months, global isovolumetric relaxation time (IVRTglobal) had increased in FG (64.0 [7.5] vs. 73.9 [9.4] ms, P < 0.001) while other examined LV diastolic function variables were not altered. No echocardiographic changes were observed in CG. Between-group differences in pre-post delta values were observed for systolic blood pressure, TAPSE, and IVRTglobal (P = 0.02–0.03). We conclude that short-term football training may have positive structural and functional effects on the cardiovascular system in overweight preadolescent children.

Heart rate response and fitness effects of various types of physical education for 8- to 9-year-old schoolchildren.

Abstract The present study investigated the heart rate (HR) response to various types of physical education (PE) activities for 8- to 9-year-olds (five school classes, n = 93) and the fitness effects of a short-term PE training programme (three of the five classes, n = 59) with high compared to low-to-moderate aerobic intensity. HR was recorded during small-sided indoor soccer (SO), basketball (BB), unihockey (UH), circuit training (CT), walking (W) and Nintendo Wii Boxing (NWB) and Nintendo Wii Tennis (NWT). Maximal HR (HRmax) and physical fitness was determined by the Yo-Yo Intermittent Recovery Level 1 Childrens test (YYIR1C) test. Following cluster randomisation, three classes were tested before and after 6 wks with 2 × 30 min/wk SO and UH lessons [high-intensity (HI), 2 classes, n = 39] or low-to-moderate intensity PE lessons (CON, 1 class, n = 20). Average HR in SO (76 ± 1% HRmax), BA (77 ± 1% HRmax) and UH (74 ± 1% HRmax) was higher (P < 0.05) than in CT (62 ± 1% HRmax), W (57 ± 1% HRmax), NWB (65 ± 2% HRmax) and NWT (57 ± 1% HRmax). Time with HR > 80% and 90% HRmax, respectively, was higher (P < 0.05) in SO (42 ± 4 and 12 ± 2%), BB (41 ± 5 and 13 ± 3%) and UH (34 ± 3 and 9 ± 2%) than in CT, W and NW (0–5%), with time >80% HRmax being higher (P < 0.05) in SO than UH. After 6 wk, YYIR1C performance was increased (P < 0.05) by 22% in HI (673 ± 57 to 821 ± 71 m), but unaltered in CON (674 ± 88 to 568 ± 81 m). HR 2 min into YYIR1C was lowered (P < 0.05) in HI after 6 wks (92.4 ± 0.8 to 89.1 ± 0.9% HRmax), but not in CON. In conclusion, ball games elicited high aerobic loading for young schoolchildren and a short-term, low-volume ball game PE-intervention improved physical fitness. Traditional PE sessions had no effects on intermittent exercise performance.