Abstract Post-activation potentiation (PAP) is a phenomenon where force output is acutely enhanced following muscular contraction. Previous research has documented enhanced performance in power-type light exercise following a heavy pre-load, such as vertical jumps following heavy squats. To date, the effect of PAP on moderately heavy exercise following a heavy pre-load has not been investigated. Purpose: The purpose was to examine whether PAP could be elicited in moderately heavy squats following a heavy squat pre-load, and if so, what intensity (as percentage of one repetition-maximum [1RM]) of pre-load elicited the highest PAP effect (measured as mean power, mean force and number of repetitions performed). Subjects: Seventeen resistance-trained males (age 24±2 years, length 182±8 cm, body mass 84.7±13.1 kg, squat 1RM 147.6±29.6 kg) with at least 2 years of experience of the squat exercise. Methods: After testing parallel squat 1RM at a separate session, subjects performed three testing sessions in a randomized order in a cross-over design; performance test at 80% of parallel squat 1RM (control), one repetition at 85% of 1RM followed 8 minutes later by the same performance test (PAP85), and one repetition at 93% of 1RM followed 8 minutes later by the same performance test (PAP93). Sessions were separated by six days. Force and power output was recorded using a linear encoder. Friedman’s test was used to reveal differences between conditions, and a Wilcoxon signed rank test was used to identify these differences. Results: There was an increase in number of repetitions performed for PAP85 (p=0.009) and PAP93 (p=0.001) compared to control, but not for mean power or mean force. There was no significant difference between PAP85 and PAP93 for number of repetitions (p=0.091). Conclusion: PAP can be elicited to improve performance in moderately heavy squats following a heavy squat pre-load in trained subjects, but only measured as number of repetitions performed, not force or power. PAP could therefore be useful not only for designing power training, but also for strength and hypertrophy training. KEYWORDS: squat, post-activation potentiation, PAP, strength, power, hypertrophy.

Background: Post activation potentiation (PAP) is an increased muscular performance thatoccurs after maximal voluntary contraction. Previous studies have shown a significantincrease in explosive movements, such as sprint and jump performance, as an effect ofthese maximal contractions. Aim: The aim of this study was to analyze if PAP, in terms of heavy squats, has aperformance enhancing effect on 30 meter sprint, with a hypothesis that the maximal effortin the squat has a performance enhancing effect on 30 meter sprint. Method: Twelve healthy male Crossfit athletes from Crossfit Halmstad, age between x-x,volunteered to participate in the study, eleven of these completed all of the test sessions in thiscross-sectional study. During the first test session, the subjects attempted to set a onerepetition max (1RM) in the back squat. During the second and third test session, the subjectswere randomly divided into two groups and the subjects got to perform both the non-PAP andthe PAP protocol during different sessions, depending on which group they were in. Thesprint time was measured with a handheld stopwatch. Wilcoxon Signed Rank Test was usedto determine significant differences between sprint time after the two different protocols, andthe level of significance was set at p < 0.05. Result: The result showed that there was no significant difference between PAP and non-PAPprotocols (p = 0,679). With a median value of 4,78 seconds, a minimum value of 4,59seconds and a maximum value of 5,54 seconds for the sprint trials after PAP and a medianvalue of 4,82 seconds, a minimum value of 4,59 seconds and a maximum value of 5,31seconds for the sprint trials without PAP, the results did not confirm the hypothesis. Conclusion: As an effect from the low number of participants, the result could be deceptive.The study could have show a different result if the number of participants would exceed atleast 25 subjects. There are no performance enhancing effects in the sprint after PAP, in thisstudy. Further research is required, to determine possible performance enhancing effectsfrom PAP.

Post activation potentiation (PAP) är ett fenomen genom vilket idrottslig prestation ökas som en följd av tidigare muskelkontraktioner. Tung styrketräning har visat sig ge en akut förbättring vid dynamiska aktiviteter som involverar samma muskelgrupper som styrketräningen. Syftet med denna studie var att undersöka kraftutvecklingsegenskaperna i underkroppen efter ett maximalt marklyftsprotokoll och två olika vilointervaller. Frågeställningar Kommer ett marklyftsprotokoll kunna ge en förbättrad prestation i längdhopp utan ansats? Vilket av experimentets vilointervaller är optimalt för användning av PAP vid hopp efter marklyft? Finns det någon korrelation mellan PAP och atleternas styrka? Metod Tio aktiva styrketräningsutövare (30.8 ± 5.9 år, längd 176.4 ± 7.8 cm, vikt 74.2 ± 12.11 kg) deltog i en experimentell studie bestående av tre delar. Vid första tillfället mättes deltagarnas 1 repetition maximum i marklyft. Vid det andra, respektive det tredje tillfället fick deltagarna utföra längdhopp både före ett marklyftsprotokoll och 2.5 (tillfälle 2), respektive 4 (tillfälle 3) minuter efter marklyftprotokollet. Resultat Ett marklyftsprotokoll där vikten ökas från 40 % till 100 % 1RM leder till en medelsnittökning i prestation i längdhopp utan ansats på 7,95 ± 8,86 cm, p=0,0195. Båda vilointervallerna visade sig vara lika gynnsamma för prestation i längdhopp efter marklyft. Det fanns ett måttligt positiv samband mellan PAP och deltagarnas styrka (r=0.43). Slutsats Den praktiska betydelsen av dessa resultat är att idrottare bör försöka genomföra tunga marklyft för att förbättra sin prestation i längdhopp utan ansats. Fler omfattande studier behövs för att mer detaljerat undersöka en optimal vilotid mellan marklyft och längdhopp, samt typen av atleter som kan ha mest nytta av ett protokoll som i föreliggande studie. / <p>Fristående kurs: Idrott III</p>

O efeito da potencialização pós-ativação (PPA) tem sido estudado, mas a sua aplicação no desempenho de atletas é muito controversa. Estudos descrevem a possibilidade de que a PPA possa compensar o mecanismo de fadiga, aumentando a taxa de desenvolvimento de força e melhorando a potência muscular. O objetivo deste estudo foi avaliar os efeitos agudos e crônicos de um treinamento pliométrico com e sem indução da PPA na potência muscular de membros inferiores em atletas de voleibol. A amostra foi composta por 16 atletas de voleibol masculino participantes da Superliga Nacional, divididos em grupo pliométrico (GPLIO) e grupo PPA (GPPA). O grupo pliométrico foi submetido a um treinamento de pliometria e o grupo PPA acrescentou ao treinamento pliométrico uma rotina de treinos que estimularam o mecanismo de PPA. O período de treinamento foi de 4 semanas com 2 sessões semanais. Durante a avaliação do pré e pós-treinamento para a determinação dos efeitos crônicos, foi mensurada a potência muscular dos membros inferiores através do salto vertical counter movement jump (CMJ), conforme protocolo sugerido por Bosco (1994), em uma plataforma de força, e contração voluntária máxima para a musculatura da articulação do joelho em um equipamento isocinético. Na avaliação pré e pós-teste para a determinação do efeito agudo, foi utilizado um tapete de contato para obtenção da altura de salto vertical CMJ. Para análise estatística foi utilizado o teste de equações de estimação generalizadas (GEE) no fator tempo e no fator grupo para determinar os efeitos do treinamento em cada grupo (GPLIO e GPPA). Os resultados referente aos efeitos agudos indicam a interação grupo*tempo para o grupo PPA significativa de p<0,001 (38,26 cms / 44,51 cms) do período pré-treinamento para o período de treinamento e de p=0,002 (38,26 cms /44,07 cms) do período pré para o pós treinamento. Ainda observamos que o grupo PPA obteve altura de salto significativamente melhor ao grupo PLIO, tanto no período de treinamento (44,51 cms/35,38cms) como no pós-treinamento pliométrico (44,07cms / 39,32 cms). Quanto aos efeitos crônicos, os resultados demonstraram não haver diferença significativa para as variáveis de torque isocinético. No que diz respeito à altura e potência de salto após o treinamento crônico foi observada diferença significativa nos dois grupos do período pré para o pós-treinamento, não havendo diferença entre os grupos. Concluímos que o treinamento pliométrico com indução de PPA melhora os efeitos agudos do salto vertical, tanto durante o treinamento como até 80 minutos após o treinamento pliométrico. Já no que diz respeito aos efeitos crônicos da indução ou não de PPA no treinamento pliométrico, os resultados indicam não haver diferença significativa no torque isocinético dos músculos extensores do joelho, porém na altura de salto CMJ e potência os resultados indicam que os dois modelos de treinamento têm uma resposta semelhante. / The effect of post-activation potentiation (PPA) has been studied, but its application in the performance of athletes is very controversial. Studies have described the possibility that PPP can compensate for the fatigue mechanism, increasing the rate of strength development and improving muscle power. The objective of this study was to evaluate the acute and chronic effects of a plyometric training with and without PPA induction on lower limb muscle power in volleyball athletes. The sample consisted of 16 male volleyball players participating in the National Superliga, divided into plyometric group (GPLIO) and PPA group (GPPA). The plyometric group underwent a plyometrics training and the PPA group added to the plyometric training a routine of training that stimulated the PPA mechanism. The training period was 4 weeks with 2 weekly sessions. During the pre and post-training evaluation for the determination of the chronic effects, the muscular power of the lower limbs was measured through the vertical jump movement movement (CMJ), according to a protocol suggested by Bosco (1994), on a force platform, And maximal voluntary contraction for the musculature of the knee joint in an isokinetic equipment. In the pre and post-test evaluation for the determination of the acute effect, a contact mat was used to obtain the vertical jump height CMJ. For statistical analysis, the test of generalized estimation equations (GEE) in the time factor and in the group factor was used to determine the effects of the training in each group (GPLIO and GPPA). The results for the acute effects indicate the group*time interaction for the PPA group significant of p<0.001 (38.26 cms / 44.51 cms) of the pre-training period for the training period and p=0.002 (38, 26 cm / 44.07 cm) from the pre and post training period. We also observed that the PPA group had a significantly better jump height in the PLIO group, both in the training period (44.51 cm / 35.38 cm) and in the plyometric training (44.07 cm / 39.32 cm). Regarding the chronic effects, the results showed no significant difference for the isokinetic torque variables. Regarding the height and jumping power after the chronic training, a significant difference was observed in the two groups from the pre-post-training period, with no difference between the groups. We conclude that plyometric training with PPA induction improves the acute effects of vertical jump, both during training and up to 80 minutes after plyometric training. Regarding the chronic effects of PPA or non-PPA induction in plyometric training, the results indicate that there is no significant difference in the isokinetic torque of the knee extensor muscles, but at the height of the CMJ and power jump the results indicate that the two models of Have a similar response.

Orientador: Alessandro Moura Zagatto / Banca: Daniel Alexandre Boullosa / Banca: Claudio Alexandre Gobatto / Resumo: O objetivo do presente estudo foi investigar os efeitos da potenciação pós ativação (PAP) induzida por drop jumps no tempo até a exaustão a 115% da intensidade associada ao consumo máximo de oxigênio (("iV" ) ̇"O" _"2max" ) em ciclo ergômetro, em aspectos neuromusculares da fadiga (central e periférica) e sobre as vias metabólicas não oxidativas (capacidade anaeróbia, via glicolítica e dos fosfagênios). Para isso, o projeto foi dividido em dois estudos independentes. No Estudo A, 14 ciclistas recreacionais do sexo masculino (34 ± 4 anos) foram submetidos a 5 sessões de avaliações. Na primeira sessão realizaram teste incremental até exaustão (TInc), na segunda e terceira avaliações realizaram familiarização ao esforço supramáximo a 115% da ("iV" ) ̇"O" _"2max", enquanto que na quarta e quinta sessões os participantes realizaram de maneira randomizada o esforço supramáximo a 115% da ("iV" ) ̇"O" _"2max" com e sem PAP (controle). Como esforço indutor da PAP, foram realizados 5 drop jumps (15s de intervalo entre eles) antes do esforço supramáximo. Nas sessões 4 e 5, a fadiga neuromuscular foi avaliada por meio de contrações voluntárias máximas (CVM) de extensão do joelho e estimulação elétrica periférica (PNS) realizadas antes e após o esforço supramáximo. Além disso, a eletromiografia de superfície foi realizada durante o esforço supramáximo para mensuração da roots mean square (EMGRMS) e a frequência mediana (EMGFM) e analisadas de forma estratificada a cada 25% de tempo total... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of the present study was investigating the effects of post activation potentiation (PAP) induced by drop jumps in performance during a supramaximal effort at 115% of the intensity associated with maximal oxygen uptake (iV̇ O2max) on a cycle ergometer, also investigating the influence of PAP on neuromuscular fatigue (central and peripheral) and, on the non-oxidative metabolic pathways (anaerobic capacity, glycolytic pathway and phosphagen). Therefore, the project was divided in two independent studies. In Study A, 14 recreational male cyclists (34 ± 4 years) underwent 5 sessions of evaluations, in the first session they performed a graded exercise test (GXT), in the second and third evaluations they performed familiarization to the supramaximal effort to 115% of the iV̇ O2max. In the fourth and fifth sessions, the participants randomly performed the supramaximal effort at 115% of the iV̇ O2max with PAP and without PAP (control). To induce PAP, the volunteers performed 5 drop jumps (15s interval between them) 2 minutes before the supramaximal effort. In sessions 4 and 5, neuromuscular fatigue was assessed by maximal voluntary contractions (CVM) of knee extension with peripheral electrical stimulation (SNP) performed before and after the supramaximal effort. In addition, surface electromyography was performed during the supramaximal effort to measure roots mean square (EMGRMS) and the median frequency (EMGFM) for every 25% of total effort time (0-25%, 25-50%, 50-75% and ... (Complete abstract click electronic access below) / Mestre

O efeito da potencialização pós-ativação (PPA) tem sido estudado, mas a sua aplicação no desempenho de atletas é muito controversa. Estudos descrevem a possibilidade de que a PPA possa compensar o mecanismo de fadiga, aumentando a taxa de desenvolvimento de força e melhorando a potência muscular. O objetivo deste estudo foi avaliar os efeitos agudos e crônicos de um treinamento pliométrico com e sem indução da PPA na potência muscular de membros inferiores em atletas de voleibol. A amostra foi composta por 16 atletas de voleibol masculino participantes da Superliga Nacional, divididos em grupo pliométrico (GPLIO) e grupo PPA (GPPA). O grupo pliométrico foi submetido a um treinamento de pliometria e o grupo PPA acrescentou ao treinamento pliométrico uma rotina de treinos que estimularam o mecanismo de PPA. O período de treinamento foi de 4 semanas com 2 sessões semanais. Durante a avaliação do pré e pós-treinamento para a determinação dos efeitos crônicos, foi mensurada a potência muscular dos membros inferiores através do salto vertical counter movement jump (CMJ), conforme protocolo sugerido por Bosco (1994), em uma plataforma de força, e contração voluntária máxima para a musculatura da articulação do joelho em um equipamento isocinético. Na avaliação pré e pós-teste para a determinação do efeito agudo, foi utilizado um tapete de contato para obtenção da altura de salto vertical CMJ. Para análise estatística foi utilizado o teste de equações de estimação generalizadas (GEE) no fator tempo e no fator grupo para determinar os efeitos do treinamento em cada grupo (GPLIO e GPPA). Os resultados referente aos efeitos agudos indicam a interação grupo*tempo para o grupo PPA significativa de p<0,001 (38,26 cms / 44,51 cms) do período pré-treinamento para o período de treinamento e de p=0,002 (38,26 cms /44,07 cms) do período pré para o pós treinamento. Ainda observamos que o grupo PPA obteve altura de salto significativamente melhor ao grupo PLIO, tanto no período de treinamento (44,51 cms/35,38cms) como no pós-treinamento pliométrico (44,07cms / 39,32 cms). Quanto aos efeitos crônicos, os resultados demonstraram não haver diferença significativa para as variáveis de torque isocinético. No que diz respeito à altura e potência de salto após o treinamento crônico foi observada diferença significativa nos dois grupos do período pré para o pós-treinamento, não havendo diferença entre os grupos. Concluímos que o treinamento pliométrico com indução de PPA melhora os efeitos agudos do salto vertical, tanto durante o treinamento como até 80 minutos após o treinamento pliométrico. Já no que diz respeito aos efeitos crônicos da indução ou não de PPA no treinamento pliométrico, os resultados indicam não haver diferença significativa no torque isocinético dos músculos extensores do joelho, porém na altura de salto CMJ e potência os resultados indicam que os dois modelos de treinamento têm uma resposta semelhante. / The effect of post-activation potentiation (PPA) has been studied, but its application in the performance of athletes is very controversial. Studies have described the possibility that PPP can compensate for the fatigue mechanism, increasing the rate of strength development and improving muscle power. The objective of this study was to evaluate the acute and chronic effects of a plyometric training with and without PPA induction on lower limb muscle power in volleyball athletes. The sample consisted of 16 male volleyball players participating in the National Superliga, divided into plyometric group (GPLIO) and PPA group (GPPA). The plyometric group underwent a plyometrics training and the PPA group added to the plyometric training a routine of training that stimulated the PPA mechanism. The training period was 4 weeks with 2 weekly sessions. During the pre and post-training evaluation for the determination of the chronic effects, the muscular power of the lower limbs was measured through the vertical jump movement movement (CMJ), according to a protocol suggested by Bosco (1994), on a force platform, And maximal voluntary contraction for the musculature of the knee joint in an isokinetic equipment. In the pre and post-test evaluation for the determination of the acute effect, a contact mat was used to obtain the vertical jump height CMJ. For statistical analysis, the test of generalized estimation equations (GEE) in the time factor and in the group factor was used to determine the effects of the training in each group (GPLIO and GPPA). The results for the acute effects indicate the group*time interaction for the PPA group significant of p<0.001 (38.26 cms / 44.51 cms) of the pre-training period for the training period and p=0.002 (38, 26 cm / 44.07 cm) from the pre and post training period. We also observed that the PPA group had a significantly better jump height in the PLIO group, both in the training period (44.51 cm / 35.38 cm) and in the plyometric training (44.07 cm / 39.32 cm). Regarding the chronic effects, the results showed no significant difference for the isokinetic torque variables. Regarding the height and jumping power after the chronic training, a significant difference was observed in the two groups from the pre-post-training period, with no difference between the groups. We conclude that plyometric training with PPA induction improves the acute effects of vertical jump, both during training and up to 80 minutes after plyometric training. Regarding the chronic effects of PPA or non-PPA induction in plyometric training, the results indicate that there is no significant difference in the isokinetic torque of the knee extensor muscles, but at the height of the CMJ and power jump the results indicate that the two models of Have a similar response.

O efeito da potencialização pós-ativação (PPA) tem sido estudado, mas a sua aplicação no desempenho de atletas é muito controversa. Estudos descrevem a possibilidade de que a PPA possa compensar o mecanismo de fadiga, aumentando a taxa de desenvolvimento de força e melhorando a potência muscular. O objetivo deste estudo foi avaliar os efeitos agudos e crônicos de um treinamento pliométrico com e sem indução da PPA na potência muscular de membros inferiores em atletas de voleibol. A amostra foi composta por 16 atletas de voleibol masculino participantes da Superliga Nacional, divididos em grupo pliométrico (GPLIO) e grupo PPA (GPPA). O grupo pliométrico foi submetido a um treinamento de pliometria e o grupo PPA acrescentou ao treinamento pliométrico uma rotina de treinos que estimularam o mecanismo de PPA. O período de treinamento foi de 4 semanas com 2 sessões semanais. Durante a avaliação do pré e pós-treinamento para a determinação dos efeitos crônicos, foi mensurada a potência muscular dos membros inferiores através do salto vertical counter movement jump (CMJ), conforme protocolo sugerido por Bosco (1994), em uma plataforma de força, e contração voluntária máxima para a musculatura da articulação do joelho em um equipamento isocinético. Na avaliação pré e pós-teste para a determinação do efeito agudo, foi utilizado um tapete de contato para obtenção da altura de salto vertical CMJ. Para análise estatística foi utilizado o teste de equações de estimação generalizadas (GEE) no fator tempo e no fator grupo para determinar os efeitos do treinamento em cada grupo (GPLIO e GPPA). Os resultados referente aos efeitos agudos indicam a interação grupo*tempo para o grupo PPA significativa de p<0,001 (38,26 cms / 44,51 cms) do período pré-treinamento para o período de treinamento e de p=0,002 (38,26 cms /44,07 cms) do período pré para o pós treinamento. Ainda observamos que o grupo PPA obteve altura de salto significativamente melhor ao grupo PLIO, tanto no período de treinamento (44,51 cms/35,38cms) como no pós-treinamento pliométrico (44,07cms / 39,32 cms). Quanto aos efeitos crônicos, os resultados demonstraram não haver diferença significativa para as variáveis de torque isocinético. No que diz respeito à altura e potência de salto após o treinamento crônico foi observada diferença significativa nos dois grupos do período pré para o pós-treinamento, não havendo diferença entre os grupos. Concluímos que o treinamento pliométrico com indução de PPA melhora os efeitos agudos do salto vertical, tanto durante o treinamento como até 80 minutos após o treinamento pliométrico. Já no que diz respeito aos efeitos crônicos da indução ou não de PPA no treinamento pliométrico, os resultados indicam não haver diferença significativa no torque isocinético dos músculos extensores do joelho, porém na altura de salto CMJ e potência os resultados indicam que os dois modelos de treinamento têm uma resposta semelhante. / The effect of post-activation potentiation (PPA) has been studied, but its application in the performance of athletes is very controversial. Studies have described the possibility that PPP can compensate for the fatigue mechanism, increasing the rate of strength development and improving muscle power. The objective of this study was to evaluate the acute and chronic effects of a plyometric training with and without PPA induction on lower limb muscle power in volleyball athletes. The sample consisted of 16 male volleyball players participating in the National Superliga, divided into plyometric group (GPLIO) and PPA group (GPPA). The plyometric group underwent a plyometrics training and the PPA group added to the plyometric training a routine of training that stimulated the PPA mechanism. The training period was 4 weeks with 2 weekly sessions. During the pre and post-training evaluation for the determination of the chronic effects, the muscular power of the lower limbs was measured through the vertical jump movement movement (CMJ), according to a protocol suggested by Bosco (1994), on a force platform, And maximal voluntary contraction for the musculature of the knee joint in an isokinetic equipment. In the pre and post-test evaluation for the determination of the acute effect, a contact mat was used to obtain the vertical jump height CMJ. For statistical analysis, the test of generalized estimation equations (GEE) in the time factor and in the group factor was used to determine the effects of the training in each group (GPLIO and GPPA). The results for the acute effects indicate the group*time interaction for the PPA group significant of p<0.001 (38.26 cms / 44.51 cms) of the pre-training period for the training period and p=0.002 (38, 26 cm / 44.07 cm) from the pre and post training period. We also observed that the PPA group had a significantly better jump height in the PLIO group, both in the training period (44.51 cm / 35.38 cm) and in the plyometric training (44.07 cm / 39.32 cm). Regarding the chronic effects, the results showed no significant difference for the isokinetic torque variables. Regarding the height and jumping power after the chronic training, a significant difference was observed in the two groups from the pre-post-training period, with no difference between the groups. We conclude that plyometric training with PPA induction improves the acute effects of vertical jump, both during training and up to 80 minutes after plyometric training. Regarding the chronic effects of PPA or non-PPA induction in plyometric training, the results indicate that there is no significant difference in the isokinetic torque of the knee extensor muscles, but at the height of the CMJ and power jump the results indicate that the two models of Have a similar response.

Purpose: To examine the effect of three muscle potentiation protocols on changes in muscle architecture and the subsequent effect on jump power performance. Methods: Maximal (1RM) squat strength (Mean SD=178.3 ± 36.6kg), vertical jump power, and muscle architecture were obtained in 12 resistance trained men (25.2±3.6y; 90.67±12.7kg). Participants randomly completed three squatting protocols at 75% (3 x 10 reps), 90% (3 x 3 reps) or 100% (1 x 1) of their 1RM, or no workout (CON), with each protocol being separated by one week. During each testing session ultrasound and vertical jump testing were assessed at baseline (BL), 8min post (8P) and 20min post (20P) workout. Ultrasound measures of the rectus femoris (RF) and vastus lateralis (VL) muscles included; cross sectional area (CSA) and pennation angle (PNG). Following each ultrasound, peak (PVJP) and mean (MVJP) vertical jump power (using hands for maximum jump height) were measured using an accelerometer. Results: Magnitude based inferences analysis indicated that in comparison to CON, 75% resulted in a likely greater change in RF-CSA and VL-CSA (BL-8P and BL–20P), 90% resulted in a likely greater RF-CSA and VL-CSA (BL–20P), and 100% resulted in a very likely or likely decrease in VL-PNG at BL-8P and BL–20P, respectively). Meanwhile, changes in PVJP and MVJP for the 75% trial was likely decreased at BL-8P and BL–20P; and for the 90% trial MVJP was likely decreased at BL-8P and BL–20P. Analysis of the magnitude of the relationships indicated a likely negative relationship between VL-PNG and MVJP (r = -0.35; p < 0.018) at BL-8P, while at BL–20P, a negative relationship was observed between PVJP and RF-CSA (r = - 0.37; p < 0.014). iii Conclusion: Acute increases in muscle size and acute decreases in pennation angle did not result in any potentiation in vertical jump power measures. Although the inverse relationships observed between muscle architecture variables and power suggests a potential effect, the change in position (i.e. movement from standing to supine for ultrasound measures) may negate, as a result of potential fluid shifts or muscle relaxation, the potentiating effects of the exercise. It is also possible that the fatiguing nature of the squat protocols in trained but not competitive participants may have also contributed to the results.

No description available.

Background: Competitive swimming is a sport that require high muscle strength to overcome the forces in the water. A phenomenon called post activation potentiation (PAP) is known to acutely increase power output. PAP can be defined as an increase in muscle performance after muscle contraction. Previous research on PAP has shown positive effects on different sports, including swimming. However, a limited amount of studies exists on PAP associated with swimming and distances longer than 100 meters. Aim: The aim of the study was to investigate if PAP for triceps brachii and latissimus dorsi with elastic bands can improve the aerobic performance, V4-speed, of elite freestyle swimmers. Methods: 13 elite swimmers participated in this study (mean ±SD: age 18 ±1.15). The participants performed three test sessions on two different days. The first occasion evaluated aerobic performance, V4-speed, where the participants performed a 400-m freestyle swim race and lactate and time were collected. At the second occasion, a 10-repetition maximum (RM) elastic resistance band test was done to get the right resistance band for each individual participant for the PAP exercise. At the third occasion, a PAP exercise, that mimics freestyle swim, with elastic resistance band was performed with 10 repetitions in two sets. After, a rest of six minutes was performed and then the same 400-m freestyle swim test as the first occasion. A paired samples t-test was used to evaluate significant differences between the swim test performed with and without a PAP exercise. Results: The study showed no statistical difference between the V4-speed with or without PAP exercise (p=0.93). An increase in lactate was seen after the PAP exercise (p=0.02). Conclusion: This study could not ensure an improvement of the aerobic performance, V4-speed, of elite swimmers when a PAP exercise, similar to a freestyle stroke, was performed before a 400-m submaximal freestyle swim race with elastic resistance band. Further research must be done in this area before coaches and athletes can apply this in training programs.