One of the most popular methods of assessment of power output during short-term maximal of exercise is the Wingate Anaerobic Test (WAnT), but this test suffers from serious conceptual limitations. Therefore, the first aim of this study was to investigate the theoretical underpinnings and practical implementation of correct power measurement in the WAnT. The second aim was to design and construct a pair of force pedals, and the last objective was to use these pedals to analyse the force application and power output of elite sprint cyclists during maximal ergometry. The inertial and frictional characteristics of Monark ergometer flywheels were assessed using 'run-down' techniques. Moments of Inertia of 0.411 (±0.001) and 0.396 (±0.002) kg.m. 2 were found for the two Monark 864 ergometers measured, with the newer 814 ergometer possessing a value of 0.962 (±0.003) kg.m. 2 . Frictional torques of 0.0025 (±0.0030) to 0.1720 (±0.00 16) N.m. were found, depending on the attachments to the flywheel and chainset. These values were then utilised to correct the power outputs obtained during the WAnT. Corrected powers were found to produce significantly (P<0.001) larger peak and mean power outputs than those obtained using uncorrected methods. The methods used also produced significantly different (P<0.01) corrected power outputs to those of Lakomy (1986), who utilised an incorrect method of'acceleration-correction'. The force pedals were found to be highly linear in calibration and force measurement, as well as suitable for ergometer cycling. These were then used to test elite sprint cyclists on a modified Monark ergometer. The results of the sprint testing of cyclists found no overall significant difference between power measured indirectly (at the flywheel) and that measured at the pedals. There were significant differences between flywheel and pedal power outputs at high pedal velocity, and this was attributed to large crank torques, in agreement with Sjøgaard (1978). Also noted were differences in force application patterns between cyclists, indicating the use of a variety of pedalling techniques. It was concluded that inertial correction of the WAnT is mandatory for the accurate measurement of power output, and that this needs to be based on sound mechanical principles. This study has also shown that is possible to measure power accurately using indirect methods. However, if the individual techniques of elite sprint cyclists are to be examined in detail, it is necessary to utilise force pedals.

Made available in DSpace on 2014-06-11T19:22:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-17Bitstream added on 2014-06-13T19:28:15Z : No. of bitstreams: 1 campos_ez_me_prud.pdf: 293105 bytes, checksum: 78b1ba74e96d963f46ae19fc0d7ee0fd (MD5) / O presente estudo investigou desempenho em saltos verticais e em teste de wingate (TW) de jogadores de futebol profissional no início da temporada e após 7 semanas de treinamento. Treze jogadores profissionais de futebol participantes da segunda divisão do campeonato paulista, foram avaliados no início da pré temporada (T1) e após 07 semanas (T2) de treinamento. Os jogadores realizaram testes de saltos verticais: squat jump (SJ) e countermovement jump (CMJ), índice de força reativa (IFR=CMJ-SJ) e TW, potência pico (PP), média (PM) e índice de fadiga (IF). Após o TW, foram coletados 25 μl de sangue do lóbulo da orelha no 7º, 9º e 11º minuto para determinação da concentração pico de lactato ([Lac]). A comparação entre as variáveis foi realizada pelo teste t de Student para amostras dependentes, sendo adotado o nível de significância de 5% (p<0,05). Foram observadas melhoras significantes no SJ (T1= 32,76 ± 3,88; T2= 38,03 ± 5,49), CMJ (T1= 37,76 ± 4,88; T2= 40,86 ± 5,62), PP (T1= 10,97 ± 0,90; T2= 12,32 ± 1,12) e PM (T1= 8,34 ± 0,82; T2= 9,78 ± 0,99), respectivamente. No entanto, alterações no IF e [Lac] não foram... / The present study investigated vertical jump and wingate test (TW) performance of soccer players in the beginning of season and after 7 weeks of training. Thirteen professional second division soccer players from the Paulista championship were tested on the beginning of the pre-season (T1) and after seven weeks (T2) of training. The players were submitted to vertical jump tests: squat jump (SJ) and countermovement jump (CMJ), reactive force index (IFR=CMJ-SJ) and TW, peak power (PP), mean power (PM) and fatigue index (IF). After TW, 25 μl blood was collected from the earlobe on the 7º, 9º and 11º minute to determine the highest blood lactate concentration ([Lac]). Comparison between variables was performed by Students’ t test for dependent sample, with a significance level of 5%. Were found significant improvements on SJ (T1= 32,76 ± 3,88; T2= 38,03 ± 5,49), CMJ (T1= 37,76 ± 4,88; T2= 40,86 ± 5,62), PP (T1= 10,97 ± 0,90; T2= 12,32 ± 1,12) e PM (T1= 8,34 ± 0,82; T2= 9,78 ± 0,99), respectively. Nevertheless, IF and [Lac] changes were ... (Complete abstract click electronic access below)

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Consumption of supplements and energy drinks is common among athletes; however, there is a lack of research on the efficacy of energy drink consumption before and during short-duration, intense exercise. The purpose of this research was to investigate the acute effects of a low-calorie, caffeine-taurine, energy drink (AdvoCare Spark®) on repeated sprint performance and anaerobic power in National Collegiate Athletic Association Division I football players. Twenty well-trained Division I football players (age: 19.7 ± 1.8 years, height: 184.9 ± 5.3 cm, weight: 100.3 ± 21.7 kg) participated in a double-blind, randomized crossover study in which they received the energy drink or an isoenergetic, isovolumetric, noncaffeinated placebo. The two trials were separated by 7 days. The Running Based Anaerobic Sprint Test (RAST), consisting of six 35-m sprints with 10 s of rest between each sprint, was used to assess anaerobic power. Sprint times were recorded with an automatic electronic timer. On average, there iv was no statistically significant difference between the placebo (15.06 ± 3.80 W·s-1) and beverage (15.3 ± 4.18 W·s-1) measurements of fatigue index. Neither were there statistically significant main effects of the beverage treatment on power F(1, 18) = 3.84, p = 0.066; or sprint time F(1, 18) = 3.06, p = 0.097. However, there was a significant interaction effect between caffeine use and the beverage for sprint times (F = 4.62, p = 0.045), as well as for anaerobic power (F = 5.40, p = 0.032), indicating a confounding effect. In conclusion, a caffeine-taurine energy drink did not improve the sprint performance or the anaerobic power of collegiate football players, but the level of caffeine use by the athletes likely influenced the effect of the drink.

Orientador: Pedro Balikian Júnior / Banca: Marcelo Papoti / Banca: Claudio Alexandre Gobatto / Resumo: O presente estudo investigou desempenho em saltos verticais e em teste de wingate (TW) de jogadores de futebol profissional no início da temporada e após 7 semanas de treinamento. Treze jogadores profissionais de futebol participantes da segunda divisão do campeonato paulista, foram avaliados no início da pré temporada (T1) e após 07 semanas (T2) de treinamento. Os jogadores realizaram testes de saltos verticais: squat jump (SJ) e countermovement jump (CMJ), índice de força reativa (IFR=CMJ-SJ) e TW, potência pico (PP), média (PM) e índice de fadiga (IF). Após o TW, foram coletados 25 μl de sangue do lóbulo da orelha no 7º, 9º e 11º minuto para determinação da concentração pico de lactato ([Lac]). A comparação entre as variáveis foi realizada pelo teste t de Student para amostras dependentes, sendo adotado o nível de significância de 5% (p<0,05). Foram observadas melhoras significantes no SJ (T1= 32,76 ± 3,88; T2= 38,03 ± 5,49), CMJ (T1= 37,76 ± 4,88; T2= 40,86 ± 5,62), PP (T1= 10,97 ± 0,90; T2= 12,32 ± 1,12) e PM (T1= 8,34 ± 0,82; T2= 9,78 ± 0,99), respectivamente. No entanto, alterações no IF e [Lac] não foram ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study investigated vertical jump and wingate test (TW) performance of soccer players in the beginning of season and after 7 weeks of training. Thirteen professional second division soccer players from the Paulista championship were tested on the beginning of the pre-season (T1) and after seven weeks (T2) of training. The players were submitted to vertical jump tests: squat jump (SJ) and countermovement jump (CMJ), reactive force index (IFR=CMJ-SJ) and TW, peak power (PP), mean power (PM) and fatigue index (IF). After TW, 25 μl blood was collected from the earlobe on the 7º, 9º and 11º minute to determine the highest blood lactate concentration ([Lac]). Comparison between variables was performed by Students' t test for dependent sample, with a significance level of 5%. Were found significant improvements on SJ (T1= 32,76 ± 3,88; T2= 38,03 ± 5,49), CMJ (T1= 37,76 ± 4,88; T2= 40,86 ± 5,62), PP (T1= 10,97 ± 0,90; T2= 12,32 ± 1,12) e PM (T1= 8,34 ± 0,82; T2= 9,78 ± 0,99), respectively. Nevertheless, IF and [Lac] changes were ... (Complete abstract click electronic access below) / Mestre

Aim The aim of this study was to ascertain the effect of resisted sprint training in swimming on maximal swimming velocity and performance characteristics. The aim was also to examine how maximal swimming velocity is related to maximal swim power and maximal dry-land power. Method Eighteen competitive national level swimmers (9 male and 9 female; age: 18.3 ± 2.3 years, body mass: 72 ± 8.3 kg, height: 177.2 ± 4.6 cm, mean ± SD) were recruited to this study. Subjects were assigned to either resisted sprint training (RST) or unresisted sprint training (UST). Sprint training was performed two times per week during 6 weeks as 8x15m with a 2min send-off interval. RST performed sprint training using individualized load corresponding 10% of maximum drag load (L10), UST performed sprint training with no added resistance. A test-battery including dry-land strength assessment; maximal strength (MxS) and explosive strength (ExS), a timed 25m front-crawl swim and in-water force-velocity profiling was performed prior and following the training intervention. Maximal swim power (Pmax), maximum drag load (F0), theoretical maximum velocity (v0) and slope of force-velocity curve (SFv) was computed though force-velocity profiling. Results No significant within group differences occurred in neither RST nor UST following the 6-week intervention period in: swimming velocity, MxS, ExS, Pmax, F0, v0, and SFv. Strong correlations were found between swimming velocity and MxS (r = 0.75), ExS (r =0.82) and Pmax (r = 0.92). Conclusion Resisted sprint training in swimming using L10 did in the present study not elicit any improvements in maximal swimming velocity or examined performance characteristics. Resisted sprint training does not appear to be a superior method of improving swimming performance compared to unresisted sprint training. MxS, ExS and Pmax can be used as robust predictors of swim performance, however only Pmax was found to be casually related to swimming velocity.

Lower body explosive power (LBEP) forms a critical component in any individual and team sport performance and it is therefore essential to develop a means of predicting LBEP in adolescents for early identification of future talent in various sporting codes. LBEP is frequently used by athletes during matches or competitions where explosive movements such as jumping, agility running and sprinting are required for successful performance. These movements are usually found in individual sports such as long jump and high jump as well as in team sports such as basketball, volleyball and soccer. To date not much literature is available on LBEP, especially with regard to LBEP prediction models. Furthermore, studies on adolescents are scarce and a LBEP prediction model has not yet been developed for a South African adolescent population. It is against this background that the objectives of this study were firstly, to develop a LBEP prediction model from various physical and motor performance components among a cohort of adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa; and secondly, to develop a LBEP prediction model from several anthropometric measurements among a cohort of male and female adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa. Two hundred and fourteen (15.8±0.68 years) 15-year-old adolescents (126 females, 88 males) from 6 surrounding schools within the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province of South Africa were purposefully selected from pre-acquired class lists took part in the study. Data was collected by means of various questionnaires as well as anthropometrical, physical and motor performance tests. For representation of LBEP a principal component factor analysis was done and the results indicated that the vertical jump test (VJT) was the best indicator of LBEP in the cohort of adolescents. With regard to the anthropometrical related LBEP prediction model, the forward stepwise regression analysis yielded a correlation coefficient of R2 = 0.69. The following variables contributed significantly (p≤0.001) to the anthropometrical LBEP prediction model: stature (57%), muscle mass percentage (10%) and maturity age (3%). The LBEP prediction model that was developed equated to LBEP (vertical jump) = -136.30 + 0.84(stature) + 0.7(muscle mass percentage) + 4.6(maturity age). Variables other than the variables that formed part of the study could explain the further 31% variance in the LBEP of the adolescents. The physical and motor performance LBEP prediction model indicated that gender (39%) and 10 m speed (7%) contributed significantly (p ≤ 0.001) to the overall prediction of the LBEP of the adolescents. The LBEP prediction model delivered a stepwise forward regression analysis coefficient of R2=0.458 and a prediction formula LBEP = 68.21 + 9.82 (gender) – 18.33(10 m speed). The remaining 56% of the variance in the results could be explained by other factors than the variables considered in the study. In conclusion, to the best of the researchers’ knowledge, this is the first study which has made an attempt at developing LBEP prediction models from the anthropometrical, physical and motor performance components of a cohort of adolescents of South Africa. The prediction models developed in the study will assist teachers sport scientists and sporting coaches who have limited resources available, to measure and calculate LBEP in adolescents, with the means to do so in South Africa. Further high quality studies are necessary to further improve and develop such prediction models for various age groups of adolescents in the greater South Africa. / MSc (Sport Science), North-West University, Potchefstroom Campus, 2014

Lower body explosive power (LBEP) forms a critical component in any individual and team sport performance and it is therefore essential to develop a means of predicting LBEP in adolescents for early identification of future talent in various sporting codes. LBEP is frequently used by athletes during matches or competitions where explosive movements such as jumping, agility running and sprinting are required for successful performance. These movements are usually found in individual sports such as long jump and high jump as well as in team sports such as basketball, volleyball and soccer. To date not much literature is available on LBEP, especially with regard to LBEP prediction models. Furthermore, studies on adolescents are scarce and a LBEP prediction model has not yet been developed for a South African adolescent population. It is against this background that the objectives of this study were firstly, to develop a LBEP prediction model from various physical and motor performance components among a cohort of adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa; and secondly, to develop a LBEP prediction model from several anthropometric measurements among a cohort of male and female adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa. Two hundred and fourteen (15.8±0.68 years) 15-year-old adolescents (126 females, 88 males) from 6 surrounding schools within the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province of South Africa were purposefully selected from pre-acquired class lists took part in the study. Data was collected by means of various questionnaires as well as anthropometrical, physical and motor performance tests. For representation of LBEP a principal component factor analysis was done and the results indicated that the vertical jump test (VJT) was the best indicator of LBEP in the cohort of adolescents. With regard to the anthropometrical related LBEP prediction model, the forward stepwise regression analysis yielded a correlation coefficient of R2 = 0.69. The following variables contributed significantly (p≤0.001) to the anthropometrical LBEP prediction model: stature (57%), muscle mass percentage (10%) and maturity age (3%). The LBEP prediction model that was developed equated to LBEP (vertical jump) = -136.30 + 0.84(stature) + 0.7(muscle mass percentage) + 4.6(maturity age). Variables other than the variables that formed part of the study could explain the further 31% variance in the LBEP of the adolescents. The physical and motor performance LBEP prediction model indicated that gender (39%) and 10 m speed (7%) contributed significantly (p ≤ 0.001) to the overall prediction of the LBEP of the adolescents. The LBEP prediction model delivered a stepwise forward regression analysis coefficient of R2=0.458 and a prediction formula LBEP = 68.21 + 9.82 (gender) – 18.33(10 m speed). The remaining 56% of the variance in the results could be explained by other factors than the variables considered in the study. In conclusion, to the best of the researchers’ knowledge, this is the first study which has made an attempt at developing LBEP prediction models from the anthropometrical, physical and motor performance components of a cohort of adolescents of South Africa. The prediction models developed in the study will assist teachers sport scientists and sporting coaches who have limited resources available, to measure and calculate LBEP in adolescents, with the means to do so in South Africa. Further high quality studies are necessary to further improve and develop such prediction models for various age groups of adolescents in the greater South Africa. / MSc (Sport Science), North-West University, Potchefstroom Campus, 2014

Made available in DSpace on 2014-06-11T19:22:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-05-17Bitstream added on 2014-06-13T19:49:12Z : No. of bitstreams: 1 afonso_m_me_rcla.pdf: 222236 bytes, checksum: 1a0edd0d0141d788c0b3436c47d1f119 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O limiar anaeróbio (LAN) tem sido muito utilizado como preditor da capacidade aeróbia na avaliação e prescrição do treinamento. Dentre os protocolos de determinação do LAN, o método do lactato mínimo (LM) parece ser um dos mais precisos, determinando de certa forma, individualmente os valores do LAN. Um outro modelo utilizado na avaliação do parâmetro aeróbio é o método não invasivo de determinação de potência crítica (PC), sendo que esse modelo possibilita também a quantificação das reservas anaeróbias intramusculares (CTA). Vários autores propõem determinações de PC por diferentes protocolos, dentre eles, os propostos por JENKINS & QUIGLEY em 1991 (PCJQ) e CHASSAIN em 1986 (PCCH) especialmente, são muito diferentes, no aspecto metodológico e repercutiram bastante no meio científico. O objetivo do presente estudo foi de comparar métodos invasivos e não invasivos de avaliação aeróbia e anaeróbia em atletas ciclistas, identificando a relação existente entre o LM e a PC (determinada por dois métodos diferentes) e, a relação dos parâmetros anaeróbios, através da potência média e da potência pico com a CTA. Foram voluntários desse estudo 9 ciclistas treinados do sexo masculino (24,11 1,62 anos; 67,28 4,37 kg e 175,78 5,89 cm) com experiência na modalidade. Os atletas foram submetidos a três protocolos experimentais: 1) Teste de LM, com teste de Wingate para induzir a acidose e posterior exercício progressivo; 2) Teste de PCJQ com quatro sessões de cargas exaustivas randômicas; 3) Teste de PCCH a partir da variação da freqüência cardíaca e do lactato através de dois esforços de 180 segundos com intervalo de pausa de 90 segundos entre os esforços, com intensidade de 85, 95, 105 e 115% do LM. Foram encontradas diferenças significativas entre as intensidades de LM (219,73 4,43 W), PCJQ nos modelos Pot- 1/tlim... . / The anaerobic threshold (AT) has been used as a good predictor of the aerobic capacity for physical evaluation and training prescription. Among the protocols of AT determination, the lactate minimal test (LMT) seems to be one of the most accurate for obtain individually the AT values. Another model used in the aerobic evaluation is the non-invasive method for determination of the critical power (CP), and this model also makes possible the quantification of the intramuscular anaerobic stores, which represents the anaerobic work capacity (AWC). Several authors proposed determinations of CP on different protocols, as those propored by, Jenkins & Quigley (1991 - CPJQ) and Chassain (1986 - CPCH), that in spite of the very different methodological aspects they are a reference in the scientific way. The purpose of the present study was to compare invasive and non-invasive protocols to evaluate the aerobic and anaerobic fitness (by two different methods) in cyclists. Also, the relationship of the mean and peak power obtained during an Wingate test to AWC identified by different methods was investigate. Nine male trained cyclists volunteered to the study (24.11 l 1.62 years; 67.28 l 4.37 kg and 175.78 l 5.89 cm). The athletes were submitted to three experimental protocols: 1) LMT, with initial lactic acidosis induced thought a Wingate test and a subsequent incremental exercise test; 2) test of PCJQ with four sessions of random exhaustive loads; 3) test of PCCH based on the variation of the heart rate and lactate along two bouts of efforts of 180 seconds with pause interval of 90 seconds between them, with intensity of 85, 95, 105 and 115% of LMT. Our results showed significant differences among the intensities of LMT (219.73 l 4.43 W), PCJQ in the models P-1/tlim (301.47 l 10.46 W) and Wlim - tlim (295.22 l 10.14 W) and, in PCCH for the methods of lactate variation (201.53 l 4.44 W) and... (Complete abstract, click electronic address below).

Orientador: Claudio Alexandre Gobatto / Banca: Eduardo Kokubun / Banca: Herbert Gustavo Simões / Resumo: O limiar anaeróbio (LAN) tem sido muito utilizado como preditor da capacidade aeróbia na avaliação e prescrição do treinamento. Dentre os protocolos de determinação do LAN, o método do lactato mínimo (LM) parece ser um dos mais precisos, determinando de certa forma, individualmente os valores do LAN. Um outro modelo utilizado na avaliação do parâmetro aeróbio é o método não invasivo de determinação de potência crítica (PC), sendo que esse modelo possibilita também a quantificação das reservas anaeróbias intramusculares (CTA). Vários autores propõem determinações de PC por diferentes protocolos, dentre eles, os propostos por JENKINS & QUIGLEY em 1991 (PCJQ) e CHASSAIN em 1986 (PCCH) especialmente, são muito diferentes, no aspecto metodológico e repercutiram bastante no meio científico. O objetivo do presente estudo foi de comparar métodos invasivos e não invasivos de avaliação aeróbia e anaeróbia em atletas ciclistas, identificando a relação existente entre o LM e a PC (determinada por dois métodos diferentes) e, a relação dos parâmetros anaeróbios, através da potência média e da potência pico com a CTA. Foram voluntários desse estudo 9 ciclistas treinados do sexo masculino (24,11 1,62 anos; 67,28 4,37 kg e 175,78 5,89 cm) com experiência na modalidade. Os atletas foram submetidos a três protocolos experimentais: 1) Teste de LM, com teste de Wingate para induzir a acidose e posterior exercício progressivo; 2) Teste de PCJQ com quatro sessões de cargas exaustivas randômicas; 3) Teste de PCCH a partir da variação da freqüência cardíaca e do lactato através de dois esforços de 180 segundos com intervalo de pausa de 90 segundos entre os esforços, com intensidade de 85, 95, 105 e 115% do LM. Foram encontradas diferenças significativas entre as intensidades de LM (219,73 4,43 W), PCJQ nos modelos Pot- 1/tlim... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The anaerobic threshold (AT) has been used as a good predictor of the aerobic capacity for physical evaluation and training prescription. Among the protocols of AT determination, the lactate minimal test (LMT) seems to be one of the most accurate for obtain individually the AT values. Another model used in the aerobic evaluation is the non-invasive method for determination of the critical power (CP), and this model also makes possible the quantification of the intramuscular anaerobic stores, which represents the anaerobic work capacity (AWC). Several authors proposed determinations of CP on different protocols, as those propored by, Jenkins & Quigley (1991 - CPJQ) and Chassain (1986 - CPCH), that in spite of the very different methodological aspects they are a reference in the scientific way. The purpose of the present study was to compare invasive and non-invasive protocols to evaluate the aerobic and anaerobic fitness (by two different methods) in cyclists. Also, the relationship of the mean and peak power obtained during an Wingate test to AWC identified by different methods was investigate. Nine male trained cyclists volunteered to the study (24.11 l 1.62 years; 67.28 l 4.37 kg and 175.78 l 5.89 cm). The athletes were submitted to three experimental protocols: 1) LMT, with initial lactic acidosis induced thought a Wingate test and a subsequent incremental exercise test; 2) test of PCJQ with four sessions of random exhaustive loads; 3) test of PCCH based on the variation of the heart rate and lactate along two bouts of efforts of 180 seconds with pause interval of 90 seconds between them, with intensity of 85, 95, 105 and 115% of LMT. Our results showed significant differences among the intensities of LMT (219.73 l 4.43 W), PCJQ in the models P-1/tlim (301.47 l 10.46 W) and Wlim - tlim (295.22 l 10.14 W) and, in PCCH for the methods of lactate variation (201.53 l 4.44 W) and... (Complete abstract, click electronic address below). / Mestre