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This study aimed to investigate how different strategies of task constraint manipulation impact physical and tactical demands in small-sided and conditioned games (SSCG). Ten recreational U-17 soccer players participated in this study (16.89 ± 0.11 years). We used different strategies of task manipulation to design two 4 vs. 4 SSCG: Structural SSCG and Functional SSCG. In Structural SSCG, pitch format and goal sizes were manipulated, while in Functional SSCG, players were allowed to kick the ball twice and at least 5 passes to shoot at the opponent's goal. Players participated in four Structural and Functional SSCG, of five minutes duration with a two-minute interval in between. Players' physical performance and tactical behavior were assessed using the WIMU PROTM inertial device. Structural SSCG stimulated players to cover more distance in sprinting (p = 0.003) and high-speed running (p < 0.001). Regarding tactical behavior, Structural SSCG stimulated players to explore game space better (p < 0.001). Moreover, Functional SSCG stimulated players to be closer to the ball, decreasing the effective playing space (p = 0.008). We conclude that these strategies of task constraint manipulation impact physical and tactical demands of the game.

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BACKGROUND: Work ability depends on a balance between individual resources and work demands. OBJECTIVE: This study evaluated factors that are associated with inadequate work ability among workers in the clothing industry. METHOD: We conducted a cross-sectional observational study of 306 workers in 40 small and medium-sized enterprises. We assessed work ability, individual resources, physical and psychosocial demands, and aspects of life outside work using a binary logistic regression model with hierarchical data entry. RESULTS: The mean work ability was 42.5 (SD=3.5); when adjusted for age, only 11% of the workers showed inadequate work ability. The final model revealed that smoking, high isometric physical load, and poor physical environmental conditions were the most significant predictors of inadequate work ability. CONCLUSIONS: Good working conditions and worker education must be implemented to eliminate factors that can be changed and that have a negative impact on work ability. These initiatives include anti-smoking measures, improved postures at work, and better physical environmental conditions.

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Os objetivos do presente estudo foram: a) descrever a demanda física imposta aos árbitros de futebol brasileiros durante partidas oficiais e b) analisar se o nível de aptidão física interfere no desempenho da arbitragem. Os árbitros (n = 11) foram avaliados durante jogos oficiais (n = 21) do campeonato Potiguar 2009. A média de idade foi de 36,36 ± 6,34 anos. A distância percorrida, a velocidade (média e máxima) e a frequência cardíaca (média e máxima) foram registradas durante as partidas. A análise da arbitragem foi realizada por avaliador credenciado pela Federação Norte-Rio-Grandense de Futebol (FNF), seguindo os critérios estabelecidos pela Confederação Brasileira de Futebol (CBF). A distância percorrida, a velocidade e a frequência cardíaca foram, respectivamente, 10,50 ± 0,35 km, 6,43 ± 0,26 km/h (média), 19,84 ± 1,56 km/h (máxima), 162,77 ± 7,44 bpm (média) e 182,22 ± 7,72 bpm (máxima). Foi evidenciada correlação significativa entre o VO2máx e a distância percorrida no segundo tempo (r = 0,517) (p < 0,05). O VO2máx também apresentou correlação com a velocidade máxima de deslocamento (r = 0,506) (p < 0,05). Já o percentual de gordura apresentou correlação negativa com a velocidade máxima no segundo tempo (r = -0,471) (p < 0,05). Foi detectada correlação positiva entre o desempenho da arbitragem e o VO2máx (r = 0,530) (p < 0,05). Com relação ao percentual de gordura, o mesmo apresentou correlação negativa com o desempenho do árbitro (r = -0,496) (p < 0,05). Os resultados do presente estudo indicam que os árbitros de futebol são submetidos à alta sobrecarga física/fisiológica durante as partidas. Os resultados obtidos também sugerem que os parâmetros associados com a aptidão física (composição corporal e o VO2máx) podem interferir no desempenho da arbitragem.

The aims of the present study were to: a) report the physical demands of brazilian soccer referees during official matches and, b) assess if the level of fitness interferes in the referees' performance. The referees were examined during official games (n = 21) of the 2009 Rio Grande do Norte Soccer Federation Championship. The referees (n = 11) mean age was 36.3 ± 6.3 years. Match analysis parameters (distance covered, speed and heart rate) were assessed during official matches. The referee performance evaluation was conducted by an official member of Rio Grande do Norte Soccer Federation. The average match distance covered was 10.50 ± 0.35 km. The average speed and maximum speed were 6.43 ± 0.26 km/h and 19.84 ± 1.56 km/h, respectively. Heart rate analysis revealed the intermittent nature of the referees' activities. The HRav and HRmax were 162.77 ± 7.44 bpm and 182.22 ± 7.72 bpm, respectively. There was a positive correlation (r = 0.517; p < 0.05) between VO2max and distance covered on the second half. VO2max was also correlated with the maximum speed (r = 0.506; p < 0.05). The fat mass was negatively correlated with maximum speed on the second half (r = -0.471; p < 0.05). Regarding referee performance, it was observed a positive correlation between VO2max and referee evaluation score (r = 0.530; p < 0.05). On the other hand, fat mass was negatively correlated to referee evaluation score (r = -0.496; p < 0.05). The results present herein suggest that soccer referees were submitted to a high level of physical demands during the match. The results also indicate that soccer referees' fitness level can interfere in their performance.

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