Reliability and Validity of a Portable Traction Dynamometer in Knee-Strength Extension Tests: An Isometric Strength Assessment in Recreationally Active Men.

BACKGROUND: the study determined the validity and reliability of measurements obtained using the portable traction dynamometer (PTD) (E-Lastic, E-Sports Solutions, Brazil) and the reproducibility between evaluators (precision) in the evaluation of the isometric muscle strength of the knee extensors of healthy male adults, compared to measurements obtained with the "gold standard" computerized dynamometer (CD) (Biodex System 3, Nova York, NY, USA). METHODS: we evaluated sixteen recreationally active men (29.50 ± 7.26 years). The test-retest reliability of both equipment to determine quadriceps strength, agreement analysis, and the minimal important difference were verified. RESULTS: excellent test-retest interrater reliability was observed for absolute and relative measurements, with a low absolute error for both sets of equipment and excellent validity of the PTD against the CD, as verified by linear regression and Pearson's correlation coefficient. CONCLUSIONS: PTD is a valid and reliable instrument for assessing the isometric strength of knee extensors, with results similar to the isometric CD "gold standard".

Initial Muscle Quality Affects Individual Responsiveness of Interleukin-6 and Creatine Kinase following Acute Eccentric Exercise in Sedentary Obese Older Women.

This study aimed to evaluate the time course and responsiveness of plasma interleukin-6 (IL-6) and creatine kinase (CK) levels following acute eccentric resistance exercise in sedentary obese older women with a different muscle quality index (MQI). Eighty-eight participants (69.4 ± 6.06 years) completed an acute eccentric resistance exercise (7 sets of 10 repetitions at 110% of 10-repetition maximum with 3 min rest interval). Participants were divided into two groups: high or low MQI according to 50th percentile cut-off. The responsiveness was based on minimal clinical important difference. There were no differences between groups and time on IL-6 and CK levels (p > 0.05). However, the high MQI group displayed a lower proportion of low responders (1 for laboratory and 2 for field-based vs. 5 and 4) and a higher proportion of high responders for IL-6 (7 for laboratory and 6 for field-based vs. 4 and 5) compared to low MQI group. In addition, the high MQI group showed a higher proportion of high responders for CK (11 for laboratory and 9 for field-based vs. 6 and 6) compared to low MQI. A prior MQI screening can provide feedback to understand the magnitude response. Individual responsiveness should be taken into consideration for maximizing eccentric exercise prescription.

The experience of a training course for physical activity promotion at the primary health care setting / A experiência de curso de capacitação para promoção da atividade física na atenção primária à saúde

Evidence demonstrates the importance of physical activity (PA) promotion strategies in primary health care (PHC) as well as the lack of professional qualification in this area. We aimed to report the experience of a basic training course to conduct group classes in a pilot study of the Program Brasil em Movimento from Brazilian Ministry of Health (PBM). The course covered eight topics within 22 hours delivered remotely. In 21 days of publicity, 630 people signed up, with an average of 439 views for each class. Students evaluated the course positively (95%) and would recommend it (93%). We observed that: 1- the number of subscribers and off-line classes views demonstrate the existence of a demand for this type of qualification; 2- the remote course offering was adequate to reach professionals from all regions of Brazil; 3- offering this type of training seems essential, given the background heterogeneity of the target audience.

Evidências demonstram a importância de estratégias de promoção da atividade física no contexto da atenção primária à saúde (APS) e a carência de qualificação profissional específica nesta área. Objetivou-se relatar a experiência de um curso básico de capacitação para condução de aulas coletivas junto ao estudo piloto do Programa Brasil em Movimento, do Ministério da Saúde (PBM). O curso abrangeu oito temas com carga de 22 horas oferecidas remotamente. Em 21 dias de divulgação inscreveram-se 630 pessoas, com média de 439 visualizações das aulas. Os discentes avaliaram o curso positivamente (95%) e o recomendariam (93%). Observou-se que: 1- o número de inscritos e de visualizações das aulas indicam interesse por este tipo de qualificação; 2- a oferta do curso de modo remoto foi adequada para atingir interessados de todas regiões do Brasil; 3- a oferta desse tipo de capacitação parece ser fundamental, frente à heterogeneidade de formação do público alvo

Acute changes in muscle thickness and pennation angle in response to work-matched concentric and eccentric isokinetic exercise.

Acute changes in muscle architecture influenced by muscle swelling might be associated with chronic adaptations to resistance exercise, including skeletal muscle growth. Concentric (CON) and eccentric (ECC) muscle actions both play a role in hypertrophic processes, but the influence of each on acute indices of muscle swelling (i.e., muscle thickness (MT) and pennation angle (PA)) remains relatively unknown. Therefore, this study compared the acute changes in MT and PA in response to work-matched CON versus ECC isokinetic exercise. Twelve university-aged students performed 2 bouts of maximal isokinetic knee extensions at 120°·s-1 on the same day: 50 CON followed by a work-matched ECC bout (∼5000 J; 28 ± 5 reps) with the contralateral limb. Ultrasound images were captured from the middle and distal sites of the vastus lateralis before and immediately after each exercise bout. From these images, MT and PA were measured. Middle and distal MT (11% and 14%, respectively; p < 0.001) and middle PA (39%, p < 0.001) increased only after CON. In addition, changes in MT were strongly related to the amount of total work performed (r = 0.76) during CON. Our results suggest that when the workload is matched between CON and ECC muscle actions performed at a moderate velocity, CON actions seem to be a more potent stimulus for inducing acute changes in MT and PA.

Low-Load High-Velocity Resistance Exercises Improve Strength and Functional Capacity in Diabetic Patients.

This study investigated the effects of low-load high-velocity resistance exercises on neuromuscular and functional outcomes in patients with Type 2 diabetes (T2D) during the early-phase of resistance training. Thirty participants with T2D performed 18 training sessions (6 weeks - 3x week) in one of two groups: low-load high-velocity exercises (LLHV, n=15, 62.1±10.5 years) or recreational activities (RA, n=15 56.7 ± 19.4 years). LLHV performed resistance exercises with 3x 8reps as fast as possible with 50-60% 1RM. RA performed light activities. Strength, power, and functional tests were assessed. There was significant increasing in the knee extension peak-torque at 60°/s (7.6%) and 180°/s (12.2%), rate of force development in the LLHV group (P<0.05), whereas there were no changes in the RA group. Significant increases in functional test were observed in the LLHV group (P<0.01) with no changes in the RA group. In conclusion, the LLHV induced marked improvements in neuromuscular parameters, as well as in the functional capacity of participants with T2D.

Strength Training with Repetitions to Failure does not Provide Additional Strength and Muscle Hypertrophy Gains in Young Women.

This study investigated the effects of a 10-week resistance training to failure on neuromuscular adaptations in young women. Eighty-nine active young women were randomly assigned to one of three groups: 1) repetitions to failure (RF; three sets of repetitions to failure); 2) repetitions not to failure with equalized volume (RNFV; four sets of 7 repetitions); and 3) repetitions not to failure (RNF; three sets of 7 repetitions). All groups performed the elbow flexor exercise (bilateral biceps curl) and trained 2 days per week using 70% of 1RM. There were significant increases (p<0.05) in muscle strength after 5 (15.9% for RF, 18.4% for RNF, and 19.9% for RNFV) and 10 (28.3% for RF, 26.8% for RNF, and 28.3% for RNFV) weeks of training, with no significant differences between groups. Additionally, muscular endurance increased after 5 and 10 weeks, with no differences between groups. However, peak torque (PT) increased significantly at 180°.s-1 in the RNFV (13.7%) and RNF (4.1%) groups (p<0.05), whereas no changes were observed in the RF group (-0.5%). Muscle thickness increased significantly (p<0.05) in the RF and RNFV groups after 5 (RF: 8.4% and RNFV: 2.3%) and 10 weeks of training (RF: 17.5%, and RNFV: 8.5%), whereas no significant changes were observed in the RNF group (3.9 and 2.1% after 5 and 10 weeks, respectively). These data suggest that short-term training of repetitions to failure do not yield additional overall neuromuscular improvements in young women.

Effects of Synergist vs. NonSynergist Split Resistance Training Routines on Acute Neuromuscular Performance in Resistance-Trained Men.

Castanheira, RPM, Ferreira-Junior, JB, Celes, RS, Rocha-Junior, VA, Cadore, EL, Izquierdo, M, and Bottaro, M. Effects of synergist vs. nonsynergist split resistance training routines on acute neuromuscular performance in resistance-trained men. J Strength Cond Res 31(12): 3482-3488, 2017-The aim of this study was to evaluate the effects of synergist (SN) vs. nonsynergist (NS) split resistance training routines on the acute neuromuscular performance of the elbow flexors in resistance-trained men. Fifteen resistance-trained men (age: 23.2 ± 4.0 years, height: 173.0 ± 0.08 cm, and body mass: 78.38 ± 9.31 kg) randomly performed 3 training routines separated by an interval of 7 days: (a) pull-pull exercises (SN), which included 6 sets of 10 repetition maximum (RM) of a seated row exercise followed by 4 sets of 10RM of the preacher biceps curl exercise; (b) push-pull exercises (NS), which included 6 sets of 10RM of the bench press exercise followed by 4 sets of 10RM of the preacher biceps curl exercise; and (c) Control, which included 4 sets of 10RM of the preacher biceps curl exercise. Elbow flexors peak torque, total work, and the amplitude of electromyography signal (EMG root mean square) were measured during the elbow flexor isokinetic exercise. Peak torque was 10.2 and 3.9% higher during Control condition when compared with the SN and NS conditions, respectively (p ≤ 0.05). Peak torque was also 6.0% greater in the NS condition than the SN condition (p ≤ 0.05). Moreover, total work was 5.1% greater in the NS condition than the SN condition. Additionally, EMG findings did not differ among conditions (p > 0.05). In conclusion, a push and pull NS split routine is recommended to maximize elbow flexor training performance (i.e., lower acute loading effect) in trained subjects.

Study of muscle fatigue in isokinetic exercise with estimated conduction velocity and traditional electromyographic indicators

INTRODUCTION: In the study of human biomechanics, it is often desirable to evaluate fatigue in the muscles that are involved in performing a particular task. Identifying the phenomena responsible for this condition is a problem that in most cases is complex and requires appropriate research mechanisms. Isokinetic dynamometry (ID) and surface electromyography (SEMG) are two techniques widely used in studies on strength and muscle fatigue. Their effectiveness is conditioned upon a good understanding of their limitations and the adoption of procedures to fully exploit the potential of each one. The main goal of the present study is to verify whether the electromyographic parameters, especially the conduction velocity (CV), are sensitive to the fatigue instauration process within sets of maximal isokinetic contractions. CV is a basic physiological parameter directly related to muscle activity and still little explored in experiments combining ID and SEMG. METHODS: Instrumentation architecture that combines ID and SEMG was used to estimate electromyographic and biomechanical parameters in protocols of maximum intensity isokinetic knee extension exercises. This architecture allows for limiting the parameter estimates to a specific region of isokinetic exercise, called the isokinetic load range (ILR), where one can consider that the angular velocity is constant and the SEMG signals are cyclo-stationary. Electromyographic signals were acquired using an array of electrodes. CONCLUSION: The results suggest that CV and the other SEMG parameters, including amplitude and frequency descriptors, are sensitive to detect a fatigue process only in protocols that restrict the analysis to ILR and that also bring the subject to a state of fatigue quickly.

Fadiga muscular entre séries de exercícios isocinéticos em mulheres jovens / Muscle fatigue between isokinetic exercises sets in young women

OBJETIVO: Avaliar o efeito de dois Intervalos de Recuperação (IR) no pico de torque (PT) e no trabalho total (TT) isocinético em mulheres jovens. MÉTODOS: 17 mulheres, destreinadas, (27,2 ± 4,1 anos; 56,8 ± 6,9 kg; 162,6 ± 7,0 cm) realizaram três séries de 10 extensões isocinéticas do joelho a 60° e 180°/s, com um e dois minutos de IR. A análise estatística foi a ANOVA dois x três [IR (um e dois minutos) x série (1ª, 2ª e 3ª)] com α < 0.05. RESULTADOS: Um minuto de IR não foi suficiente para manter o PT e o TT ao longo das séries (p<0,05) a 60º (redução de 15,7% no PT e 19,8% no TT) e 180º/s (redução de 3,6% no PT e de 5,6% no TT). Dois minutos foram suficientes apenas a 180º/s. Contudo, a 60°/s, dois minutos de IR possibilitou um maior PT na segunda e na terceira série em relação a um minuto (p<0,05). CONCLUSÃO: Dois minutos são suficientes para manutenção do PT em um protocolo de treinamento isocinético a 180º/s, mas não a 60º/s em mulheres jovens.

OBJECTIVE: To examine the effect of two rest interval (RI) on isokinetic Peak Torque (PT) and total work (TW) produced by young women. METHODS: 17 untrained women (27.2 ± 4.1 yrs; 56.8 ± 6.9 kg; 162.6 ± 7.0 cm) performed three sets of 10 unilateral isokinetic knee extension repetitions at 60° and 180°/s with one and two minutes of RI. Statistical evaluation was performed using a two x three ANOVA [RI (one and two minutes) x set (1st, 2nd, 3rd)] with α < 0.05. RESULTS: One minute was not enough to keep PT and TW between sets (p<0.05) at 60º (reduction of 15.7% in PT and 19.8% in TW) and 180º/s (reduction of 3.6% in PT and 5.6% in TT). Two minutes was enough only at 180º/s. However, two minutes of RI was greater (p<0.05) than one minutes at 60°/s for PT during the 2nd and 3rd sets. CONCLUSION: Two minutes is sufficient to keep PT within typical isokinetic resistance training protocols at 180º/s, but not at 60º/s in young women.

Relationship between ventilatory threshold and muscle fiber conduction velocity responses in trained cyclists.

The relationship between surface electromyography (SEMG) amplitude and the ventilatory threshold has been extensively studied. However, previous studies of muscle fiber conduction velocity (MFCV) are scarce and present insufficient evidence concerning the relationship between MFCV and metabolic responses during cycling. Based on that fact, the purpose of this study is twofold: (1) to investigate the existence of a MFCV threshold (MFCVT) during cycling and (2) to verify if this possible breakpoint is correlated with the ventilatory threshold (VT) and the SEMG threshold (SEMGT). Eight trained male cyclists (age 36.0±9.7years) performed an incremental cycling test with initial workload of 150W gradually incremented by 20Wmin(-1) until the exhaustion. Gas analyses were conducted using a breath-by-breath open-circuit spirometry and SEMG were registered from vastus lateralis in each pedaling cycle with a linear array of electrodes. A bi-segmental linear regression computer algorithm was used to estimate VT, MFCVT and SEMGT respectively in the carbon dioxide production (VCO2), MFCV and electromyography root mean square (EMG RMS) curves. The one way ANOVA for repeated measures did not reveal any significant difference among VT (77.1±7.5% of VO2max), MFCVT (80.3±10.4% of VO2max) and SEMGT (81.9±11.7% of VO2max). The Bland and Altman procedure confirmed a good concordance between SEMGT and VT (Bias=5.5 of %VO2max) as well as MFCVT and VT (Bias=5.2 of %VO2max). The present findings suggest that muscle fiber conduction velocity threshold is a valid and reliable non-invasive tool to obtain information about ventilatory threshold in trained cyclists.

Effect of rest interval on neuromuscular and metabolic responses between children and adolescents.

The purpose of this study was to compare the effect of different rest intervals and contraction velocities on muscle recovery following resistance exercise. 18 children (11.1 ± 0.52 yrs) and 19 adolescents (15.8 ± 0.49 yrs) performed three sets of 10 isokinetic repetitions at 60°/s and 180°/s. The work-to-rest ratio (W/R) was 1:2 and 1:4 for 60°/s, and 1:6 and 1:12 for 180°/s. ANOVA revealed that children demonstrated no significant decline in PT from the first to third set with any rest interval, but there was a significant (p < .05) decline for adolescents when a W/R of 1:2, 1:4 and 1:6 were used. Adolescents demonstrated significantly greater blood lactate (BLa) concentrations than children after three sets of resistance exercise. The present study indicates that adolescents may require longer rest intervals to recover full PT when compared with children.

The behavior of action potential conduction velocity on isokinetic knee extension tests.

The present study investigates the behavior of action potential conduction velocity (CV) on each repetition of an isokinetic test set and on each set as a whole. A total of seven healthy men (27.7 ± 2.8 yrs, 1.74 ± 0.06 m, and 79.6 ± 11.0 Kg) performed 3 (three) sets of 10 (ten) maximal concentric repetitions of dominant knee extension at 60°/s on an isokinetic dynamometer, with 1 minute of rest interval between the sets. The surface electromyographic (SEMG) signals were recorded from the vastus lateralis muscle during the exercises. CV was estimated with a spectral matching method which requires the SEMG acquisition technique based on a flexible linear array of electrodes (here used with 8 electrodes and 5 mm inter-electrode distance). With the view to minimize the factors other than fatigue that also influence the CV behavior, only the extension phase of the isokinetic exercise repetition was considered for measurements. Results showed that CV usually increases during a single repetition whereas it has a decreasing tendency along the isokinetic set seen as a whole.

Isokinetic muscle evaluation of quadriceps in patients with chronic obstructive pulmonary disease.

RATIONALE: Muscle debility has a significant impact on health-related quality of life in subjects with chronic obstructive pulmonary disease (COPD), and is correlated to exacerbation and even mortality. Assessing muscle strength is extremely relevant. Lack of standardisation in numbers of sets and rest interval in isokinetic test protocol can lead to distinct results, making com- prehension and comparisons among studies difficult. AIM: To analyse the effect of two sets and three different rest intervals on isokinetic strength measurement of quadriceps tests, in order to define the adequate test protocol. METHODS: Subjects with severe or very severe COPD underwent three isokinetic tests to evaluate knee extensor muscle strength, at an angular velocity of 60°â‹…s⁻¹, with rest intervals of 30, 60 and 120 seconds. Each test consisted of two sets of five repetitions, during which peak torque, total work and fatigue index were measured. RESULTS: In 20 studied subjects (66.1 ± 7.4 years, 70 ± 10.8 kg, 167.4 ± 6.2 cm, FEV1 36.5 ± 10.1%), there were no significant differences in peak torque, total work and fatigue index, independent of number of sets or rest interval between sets. CONCLUSION: In subjects with severe or very severe COPD, quadriceps muscle strength can be evaluated by an isokinetic protocol with one set of five repetitions. If two sets are performed, a rest interval of 30 seconds is enough to ensure muscle recovery between sets.

Efeitos do intervalo de recuperação entre as séries sobre a pressão arterial após exercícios resistidos / Effects of rest interval between exercise sets on blood pressure after resistance exercises

FUNDAMENTO: Apesar de os estudos demonstrarem a ocorrência da hipotensão pós-exercício (HPE) em exercícios resistidos, ainda não há consenso sobre um protocolo ideal. OBJETIVO: Avaliar os efeitos de diferentes intervalos de recuperação (IR) entre séries de exercício resistido (ER) na pressão arterial (PA) pós-exercício. MÉTODOS: Dezesseis homens jovens sedentários e não hipertensos realizaram, de forma contrabalanceada três protocolos de ER com 1 (P1), 2 (P2) e 3 (P3) minutos de IR entre as séries, e um protocolo controle (CON). Os protocolos de ER consistiram em três séries de oito repetições em seis exercícios. As cargas utilizadas na 1ª, 2ª e 3ª série dos exercícios foram respectivamente 80, 70 e 60 por cento de 1 repetição máxima (1RM). As medidas foram realizadas em repouso (REP), 15 (T15), 30 (T30), 45 (T45), 60 (T60), 75 (T75) e 90 (T90) minutos após a sessão. Foi realizada uma análise de variância fatorial (ANOVA) com post hoc LSD. RESULTADOS: Não foi encontrada alteração significativa na PA sistólica após os protocolos. Foi encontrado um aumento significativo da PA diastólica, após o CON, nos momentos T45 e T90. Ocorreu redução significativa na PA diastólica após P1 e P3, com duração de 30 e 15 minutos respectivamente. Não foram encontradas diferenças significativas nas respostas da PA sistólica e diastólica entre os protocolos com diferentes IR. CONCLUSÃO: Parece que o IR não influencia a redução da PA sistólica após uma sessão de ER. No entanto, foi encontrada uma queda na PA diastólica (P1 e P3) com duração de até 30 minutos.

BACKGROUND: Although studies have demonstrated the occurrence of postexercise hypotension (PEH) in resistance exercises, there is still no consensus on an ideal protocol. OBJECTIVE: To evaluate the effects of different rest intervals (RI) between resistance exercise (RE) sets on postexercise blood pressure (BP). METHODS: Sixteen sedentary non-hypertensive young men performed three RE protocols with RI of 1 (P1), 2 (2) and 3 (P3) minutes between the sets, as well as a control protocol (CON), in a counterbalanced manner. The RE protocols consisted of three sets of eight repetitions in six exercises. The loads used in the 1st, 2nd, and 3rd exercise sets were 80 percent, 70 percent and 60 percent of one repetition maximum (1RM), respectively. Measurements were taken at rest (RES), 15 (T15), 30 (T30), 45 (T45), 60 (T60), 75 (T75), and 90 (T90) minutes after the session. Factorial analysis of variance (Anova) was carried out, followed by post hoc LSD. RESULTS: No significant change was found in systolic BP after the protocols. A significant increase in diastolic BP was verified after CON at timepoints T45 and T90. Significant reduction in diastolic BP occurred after P1 and P3, with duration of 30 and 15 minutes, respectively. No significant differences were found in the systolic and diastolic BP responses between the protocols with different RI. CONCLUSION: RI does not seem to influence systolic BP reduction after an RE session. However, reductions in diastolic BP (P1 and P3) lasting up to 30 minutes were observed.

[Effects of rest interval between exercise sets on blood pressure after resistance exercises]. / Efeitos do intervalo de recuperação entre as séries sobre a pressão arterial após exercícios resistidos.

BACKGROUND: Although studies have demonstrated the occurrence of postexercise hypotension (PEH) in resistance exercises, there is still no consensus on an ideal protocol. OBJECTIVE: To evaluate the effects of different rest intervals (RI) between resistance exercise (RE) sets on postexercise blood pressure (BP). METHODS: Sixteen sedentary non-hypertensive young men performed three RE protocols with RI of 1 (P1), 2 (2) and 3 (P3) minutes between the sets, as well as a control protocol (CON), in a counterbalanced manner. The RE protocols consisted of three sets of eight repetitions in six exercises. The loads used in the 1st, 2nd, and 3rd exercise sets were 80%, 70% and 60% of one repetition maximum (1RM), respectively. Measurements were taken at rest (RES), 15 (T15), 30 (T30), 45 (T45), 60 (T60), 75 (T75), and 90 (T90) minutes after the session. Factorial analysis of variance (Anova) was carried out, followed by post hoc LSD. RESULTS: No significant change was found in systolic BP after the protocols. A significant increase in diastolic BP was verified after CON at timepoints T45 and T90. Significant reduction in diastolic BP occurred after P1 and P3, with duration of 30 and 15 minutes, respectively. No significant differences were found in the systolic and diastolic BP responses between the protocols with different RI. CONCLUSION: RI does not seem to influence systolic BP reduction after an RE session. However, reductions in diastolic BP (P1 and P3) lasting up to 30 minutes were observed.

The influence of velocity overshoot movement artifact on isokinetic knee extension tests.

EXERCISE ON AN ISOKINETIC DEVICE INVOLVES THREE DISTINCT MOVEMENT PHASES: acceleration, constant velocity, and deceleration. Inherent in these phases are unique occurrences that may confound test data and, thereby, test interpretation. Standard methods of data reduction like windowing and other techniques consist of removing the acceleration and deceleration phases in order to assure analysis under constant velocity conditions. However, none of these techniques adequately quantify the velocity overshoot (VO) movement artifact which is a result of the devices resistance imposed to the limb. This study tested the influence of VO on isokinetic data interpretation. A computational algorithm was developed to accurately identify each movement phase and to delineate the VO segment. Therefore, the VO was then treated as a fourth and independent phase. A total of sixteen healthy men (26.8 ± 4.7 yrs, 1.76 ± 0.05 m, and 79.2 ± 9.4 kg) performed two sets of ten maximal concentric extension repetitions of their dominant knee (at 60°·s(-1) and 180°·s(-1)), on separate days and in a counterbalanced order, on a Biodex System 3 Pro dynamometer. All the phases of the isokinetic exercise were measured in terms of their biomechanical descriptors and according to the developed algorithm, the windowing method, and a data reduction technique that eliminates the first and last 10° of the total range of motion. Results showed significant differences (p < 0.05) between the constant velocity phases found by each method: the largest segment was obtained with the windowing method; the second one, with the algorithm; and the smallest, with data reduction technique. The point of peak torque was not affected by none of the techniques, but significant differences (p < 0.05) were found between the data including and not including the VO phase, concerning total work, time interval, and average length of load range: VO represents more than 10% of the amount calculated in constant velocity phase. As a consequence, the correct removal of VO was suggested as a required procedure to adequately interpret isokinetic tests. Therefore, the use of the proposed algorithm is advisable in order to perform analysis according to the isokinetic definition. Key pointsIsokinetic test interpretation must be focused on the constant velocity range; traditional analysis usually removes the acceleration and deceleration phases but does not give particular attention to velocity overshoot range.The study of effects of velocity overshoot artifact requires a specific method for accurately delineate its interval and investigate its impact over biomechanical descriptors; this paper proposed a computational algorithm for identifying the velocity overshoot interval.Velocity overshoot has significant impact over biomechanical descriptors analyzed during isokinetic knee extension tests at 60°·s(-1) and 180°·s(-1); the algorithm proposed is an advisable method for performing isokinetic tests analysis according to the isokinetic definition.

Isokinetic work-to-surface electromyographic signal energy ratios as a muscular fatigue indicator.

Efficiency of muscular work is usually measured as the relationship between work load and maximum exercise duration. The present study analyzes the efficiency feature as a ratio between mechanical work (WK) and the energy (E) of the surface electromyographic signal (SEMG). This relation (WK/E(SEMG)) was compared with the most common electromyographic descriptors and its behavior was observed during muscle fatigue. A total of sixteen healthy men (26.8 +/- 4.7 yrs, 175.7 +/- 4.7 cm, and 79.2 +/- 9.4 kg) performed three sets of ten maximal concentric repetitions of dominant knee extension at 60 degrees /s on an isokinetic dynamometer, with 1 minute of rest interval between the sets. The SEMG signals were recorded during the exercises. With the view to minimize the factors other than fatigue that also influence the SEMG descriptors behavior, the only isokinetic repetition phase considered for measurements was the load range. Statistical analyses showed significant correlations between WK/E(SEMG) and the traditional electromyographic fatigue indicators.