Efeitos do destreinamento e retreinamento com pesos nas variáveis neuromusculares e na capacidade funcional de idosos

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Desportos, Programa de Pós-Graduação em Educação Física, Florianópolis, 2016.O objetivo do presente estudo foi analisar os efeitos após destreinamento e retreinamento com pesos nas variáveis neuromusculares e desempenho funcional em um grupo de idosos. O grupo experimental contou com 10 participantes (sete mulheres e três homens) com idade de 64 ± 2,35 anos, massa corporal de 71,60 ± 9,22 kg, estatura de 162,16 ± 9,74 cm e indíce de massa corporal de 27,19 ± 5,32 kg/m². Foram realizadas avaliações de força, (1-RM no Leg Press 45º, avaliações isocinéticas e isométricas) e avaliações funcionais (sentar e levantar, levantar e caminhar 3 m e subir e descer escadas). O grupo foi avaliado no período pré treinamento (controle), após o período de treinamento de 12 semanas e destreinamento (16 semanas) e após o perido de retreinamento (8 semanas). Os valores de 1-RM após o período de destreinamento foram superiores ao período pré-treinamento (controle) (147 ± 43 kg vs 170 ± 27 kg; p0,05; ES: -0,18). Ocorreu aumento no pico de torque (PT) concêntrico de flexores de joelho entre os períodos de treinamento e retreinamento (81 ± 30 vs 110 ± 32 N·m, respectivamente; pAbstract : The aim of this study was to analyze neuromuscular and functional capacity (FC) in elderly after detraining and retraining of strength training. Experimental group had 10 participants (seven women and three men, aged 64 ± 2.35 years, body mass 71.60 ± 9.22 kg kg, height 162.16 ± 9.74 cm, and body mass index 27.19 ± 5.32 kg/m²). Evaluations protocols were divided into two types, strength evaluations (1-RM at Leg Press 45º, dynamic isokinetic, and isometric) and functional capacity tests (30-s chair stand, timed up and go, upstairs and down stairs test). These evaluations were made pre training, post training (12 week), post detraining (16 week) and at the end of retraining (8 week). Values after detraining period were superior to pre training period (146.7 ± 43.1 kg vs 170 ± 26,6 kg; p<0,001; effect size [ES]: 0,75), however significant losses were observed at 1-RM in Leg press 45º after detraining period (200.7 ± 40.5 vs 170 ± 26.6 kg; respectively p<0.001; ES: -0.75). After retraining period increases ocurred in relation to post detraining (193 ± 30.5 kg; ES: 0.86) and after training to end of retraining no differences were found (200.7 ± 40.5 vs 193 ± 30.5 kg; ES: -0.18). It was observed an increase in concentric peak torque (PT) of knee flexors comparing training period and end of retraining (80.7 ± 29.7 vs 110.2 ± 31.7 ES: 0.99), also same was observed when compared retraining, and control period (74.7 ± 25 N·m; p<0.05 ES: 0.74). An increase in concentric PT knee extensors at 60º·s-1 and concentric PT from knee extensors and flexors at 240º·s-1 between weeks 16 and 24. Absolute rate of force development (RFD) increased in 0 ? 200 interval between control period and retraining (464 ± 170 vs 575 ± 217 N·m·s-1; p<0.05: 0.14 ES: 0.65). An increase occurred in number of repetitions of chair stand test between control period and retraining (14.7 ± 2.7 vs 19 ± 2.5 ES: 1.66), and between detraining and retraining periods (15.8 ± 3.3 vs 19 ± 2.5 ES: 1.23). Also an increase in time were found for timed up and go test from the end of the training to detraining (4.4 ± 0.8 vs 5.1 ± 0.5 s, ES: 1.28). For climbing stairs test were found differences between control and detraining period (3.7 ± 0.9 vs 3.0 ± 0.4 s, ES: -1.8) and control to retraining (3.7 ± 0.9 vs 2.8 ± 0.5 s, ES: -1.6). Downstairs test the volunteers reduced their time to complete the task when compared with control period (3.4 ± 0.9 vs 2.7 ± 0.5 s, ES: -0.74). Based on results of present study, periodized resistance training did not promote a complete maintenance of neuromuscular variables, because the 1-RM values after detraining were below training period. In addition PT values of knee extensors and flexors, PT isometric and RFD didn`t change after training therefore no losses were found after detraining period. Resistance periodized training promote a maintenance of FC of chair stand, upstairs and down stairs test, however timed up and go test were reduced to control period level. In conclusion, a periodized retraining of eigth weeks can promote gains in 1-RM to values above control and similar to post training. Furthermore retraining can promote an increase in PT concentric and eccentric of knee flexors and performance in functional test of chair stand

Contribuições dos fatores morfológicos e neurais para a força de extensão de joelho em diferentes comprimentos musculares de ciclistas, corredores e triatletas

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Desportos, Programa de Pós-Graduação em Educação Física, Florianópolis, 2021.Sabe-se que a curva torque-comprimento pode ser alterada por meio do treinamento. Especula-se que alterações morfológicas e neurais do músculo reto femoral (RF) estejam presentes frente à prática de modalidades cíclicas. Entretanto, pouco se sabe sobre a contribuição dessas alterações para a adaptação da curva torque-comprimento. Portanto, o objetivo do presente estudo foi determinar as contribuições de fatores morfológicos e neurais na relação torque-comprimento do RF em atletas de diferentes modalidades cíclicas. Foram recrutados 10 ciclistas, 10 corredores, 10 triatletas e 10 não atletas que foram submetidos a duas visitas e quatro avaliações. Na primeira visita foi realizada a familiarização da avaliação isométrica e do nível de ativação voluntária (VAL) utilizando um dinamômetro isocinético e eletroestimulação neuromuscular (NMES), respectivamente. O joelho direito foi fixado em 60º e o quadril em 90º (0º=extensão completa). Logo após foi determinada a intensidade máxima dos pulsos simples e doublets (estímulos duplos pareados a 100 Hz). A familiarização foi composta de contrações voluntárias isométricas máximas (CVIM) de 5 s a 60º de joelho e em três posições de quadril (90º, 45º e 0º). A cada CVIM foi realizado um doublet durante o platô de torque e após a CVIM, seguido de um pulso simples. Na segunda visita, foram repetidas as avaliações isométricas prévias, porém foram incluídas as posições 30º e 90º de joelho, com o registro da ativação dos músculos vasto medial (VM), vasto lateral (VL) e RF e avaliação da VAL e arquitetura muscular. Para representar a ativação muscular foi utilizado o valor root mean square (RMS) normalizado pela M-wave dos pulsos simples. Foi avaliado o comprimento de fascículo e a espessura muscular dos músculos RF e VL por meio de ultrassonografia. Para o cálculo do comprimento do RF foi utilizado um modelo de regressão com os ângulos de quadril e joelho. A relação torque-comprimento foi estimada a partir da contribuição do RF no torque total em função do comprimento normalizado do músculo em cada posição, e as curvas foram categorizadas em ascendente, descendente e platô. Para a análise estatística foi realizado uma ANOVA para medidas repetidas three way (fatores: ângulo de quadril; joelho e modalidade). Nossos principais resultados foram que a categorização da curva torque-comprimento de parte dos triatletas (n=7) e ciclistas (n=5) ocorreu na fase descendente, enquanto que em parte dos corredores (n=6) ocorreu na fase ascendente. Já o grupo não atleta apresentou uma maior variabilidade na categorização da curva torque-comprimento. Também não encontramos diferenças no comprimento de fascículo do RF (p=0,41), ativação muscular (VL: p=0,95; RF: p=0,55; VM: p=0,62) e na VAL (p=0,49) entre as modalidades e posicionamentos. Os resultados sugerem que a curva torque-comprimento de atletas da mesma modalidade apresenta comportamento semelhante e que o volume e o tempo de treinamento são fatores determinantes para curva torque-comprimento. Em conclusão, a prática dessas modalidades pode ser um indicativo da categorização da curva torque-comprimento e o comprimento de fascículo, o valor RMS e a VAL parecem não determinar a curva torque-comprimento do RF.Abstract: It is well known that the torque-length curve can be changed due to training. It has been speculated that morphological and neural alterations of the rectus femoris muscle (RF) occur due to the practice of cyclical modalities. However, little is known about the contribution of these changes in the adaptation of the torque-length curve. Therefore, the present study aims to determine the contributions of the morphological and neural factors in the RF torque-length relationship in athletes from different cyclical modalities. Ten cyclists, 10 runners, 10 triathletes, and 10 non-athletes were recruited. Each volunteer underwent two visits and four evaluations. In the first visit, familiarization with the isometric and level of voluntary activation (VAL) protocols was carried out using an isokinetic dynamometer and neuromuscular electrical stimulation (NMES), respectively. The right knee was fixed at 60º and the hip at 90º (0º=full extension). After that, the maximum intensity of single and doublet pulses (double paired stimuli of 100 Hz frequency) was determined. Familiarization consisted of 5-s maximal voluntary isometric contractions (MVIC) with the knee at 60º and hip in three different positions (90º, 45º, and 0º). A doublet was performed at each CVIM during the torque plateau and after the CVIM, followed by a single pulse. On the second visit, the same previous assessments were performed, but the 30º and 90º knee positions were included, with the recording of the activation of vastus medialis (VM), vastus lateralis (VL), and RF muscles, VAL, and muscle architecture. To represent muscle activation, the root mean square (RMS) value normalized by the single pulse M-wave was used. The fascicle length and muscle thickness of the RF and VL muscles were assessed by ultrasonography. To calculate the RF length, a regression model using hip and knee angles was used. The torque-length relationship was estimated from the RF contribution to the total torque as a function of the normalized length of the muscle in each position, and the curves were categorized into ascending, descending, and plateau. For the statistical analysis, a three-way repeated measures ANOVA was performed (factors: hip angle, knee, and modality). Our main results were that the categorization of the torque-length curve of the majority triathletes (n=7) and part of cyclists (n=5) occurred in the descending phase, while the majority of the runners (n = 6) belong to ascending phase. However, the non-athlete group showed greater variability in the categorization of the torque-length curve. We also found no differences for RF fascicle length (p=0.41), muscle activation (VL: p=0.95; RF: p=0.55; VM: p=0.62), and VAL (p=0.49) between modalities and positions. The results suggest that the torque-length curve of athletes from the same modality has similar behavior and the years of experience and training volume are determinant factors for the torque-length curve. In conclusion, the practice of these modalities can be an indication of the categorization of the torque-length curve, and the fascicle length, muscle activation, and VAL do not seem to determine the RF torque-length curve

Use of maximal running distance performed on hoff test for anaerobic threshold prediction in soccer

OBJECTIVE: To verify the use of maximal running distance performed on Hoff test to predict the anaerobic threshold speed (sAnT). METHODS: Ten young soccer players (age of 17 ± 1 years and body mass of 64.3 ± 2.1 kg) were subjects of the study. The subjects performed 12-min test, lactate minimum test to estimate the anaerobic threshold speed and a field test called Hoff. The purpose of Hoff test was to cover the maximum distance during a period of 10min moving a soccer ball through the track by dribbling. RESULTS: The distance covered during 12-min was 2673.2 ± 64.7 m, the sAnT was 11.6 ± 0.3 km.h-1 and distance covered during test Hoff test was 1458.7 ± 49.6 m. The distance covered during Hoff test was not significantly correlated with sAnT (r = -0.20; P > 0.05) and distance covered during 12-min test (r = -0.15; P > 0.05). The sAnT did not differ of speed correspondent 90% at 12-min speed and they were statistically correlated (r = 0.65). CONCLUSION: Thus, we concluded that maximal distance covered during Hoff test cannot provides a valid prediction of the anaerobic threshold speed.OBJETIVO: Verificar a utilização da distância total percorrida no teste de Hoff como preditor da intensidade de limiar anaeróbio em jovens futebolistas. MÉTODOS: Para isso, 10 jovens jogadores de futebol (idade de 17 ± 1 ano e massa corporal de 64,3 ± 2,1 kg) participaram do estudo. Os sujeitos foram submetidos aos testes de 12 minutos, lactato mínimo para estimar a velocidade de limiar anaeróbio (vLAn) e ao teste de Hoff específico para o de futebol. O objetivo no teste de Hoff foi percorrer a máxima distância possível em 10 minutos de exercício conduzindo a bola de futebol em um circuito composto por dribles, saltos e corridas em direções diversas. RESULTADOS: A distância total percorrida no teste de 12 minutos foi 2.673,2 ± 64,7 m, a vLAn 11,6 ± 0,3 km.h-1 e a distância percorrida no Hoff 1.458,7 ± 49,6 m. A distância total percorrida no teste de Hoff não foi significativamente correlacionada com a vLAn (r = -0,20; P < 0,05) e com a distância percorrida no teste de 12 minutos (r = -0,15; P < 0,05). No entanto, a vLAn e a velocidade correspondente a 90% da velocidade média no teste de 12 minutos (12,0 ± 0,3 km.h-1) não foram diferentes significativamente e foram significativamente correlacionadas (r = 0,65; P < 0,05). CONCLUSÃO: Assim, pode-se concluir que a distância total percorrida no teste de Hoff não pode ser utilizada para predição da velocidade de limiar anaeróbia em futebolistas

Pressure on the Electrode to Reduce Discomfort During Neuromuscular Electrical Stimulation in Individuals With Different Subcutaneous-Fat Thickness: Is the Procedure Effective and Reliable?

The addition of manual pressure on the electrode during neuromuscular electrical stimulation (NMES) has been used to reduce current intensity and perceived discomfort. In this study we aimed to test i) whether this approach affect the reliability of commonly made torque output measurements and ii) whether subcutaneous-fat thickness influence the efficacy of this approach in reducing current intensity and perceived discomfort. Twenty-one men (24 ± 3.1 years) performed knee extension maximal voluntary isometric contractions with and without manual pressure on the NMES femoral nerve electrode (superimposed and resting doublets, 2 pulses at 100 Hz) during two separate sessions. Torque output was measured in an isokinetic dynamometer and thigh subcutaneous-fat thickness assessed with ultrasonography. A scale of perceived discomfort was presented after contractions. Reductions in current intensity ( ${p} ) and discomfort during superimposed doublet (${p}=0.002$) and resting doublet (${p}=0.002$) were confirmed for the condition in which pressure was applied to the electrode. Fat thickness was correlated to changes in current intensity (r = 0.63;${p}$= 0.002) and changes in discomfort (r = 0.45;${p}$= 0.04) and no differences between pressure conditions and testing sessions were observed for torque output (${p}$ > 0.05; ICC 0.95). Adding manual pressure during NMES on femoral nerve reduces discomfort and the maximal NMES intensity required to reach maximum torque without affecting torque output magnitude and reliability. Greater reduction in intensity and discomfort were observed in participants with higher subcutaneous-fat thickness levels after adding pressure on the electrode.</p

Leg press exercise can reduce functional hamstring:quadriceps ratio in the elderly

The aim of this study was to investigate whether 12 weeks of leg press strength training exercise could affect the conventional and functional hamstring:quadriceps ratios in the elderly. Twelve elderly participants were submitted to a 12 week progressive training protocol (two sessions/week) using a 45° leg press exercise. A significant increase in the one repetition maximum was observed after 4, 8, and 12 weeks (p = 0.001, p 0.314) after 12 weeks of training. The functional ratio (eccentric knee flexor peak torque:concentric knee extensor peak torque) reduced significantly after 8 (p = 0.034) and 12 (p = 0.036) weeks of strength training. Although the 45° leg press exercise requires knee extensor and flexor, hip extensor, and plantar flexor muscle strength, our findings suggest that the isolated use of the 45° leg press exercise reduces the knee functional ratio after 8 weeks of training. Therefore, 45° leg press exercise alone, without a hamstring exercise, should not be recommended for elderly individuals.</p

Is respiratory exchange ratio an alternative to estimate anaerobic threshold in trained runners?

Several studies showed that respiratory exchange ratio (RER) have been used as an alternative to evaluate the aerobic capacity in a single incremental test. However, few studies have investigated trained runners. The aim of this study was to verify if the respiratory exchange ratio (RER) could be used as an alternative criterion for estimating anaerobic threshold (AT) in long-distance runners. Nineteen male long-distance runners volunteered to participate in the study. An incremental treadmill test was performed with initial speed of 10 km·h-1 with increments of 1 km·h-1 every 1 min until voluntary exhaustion. The variables measured were oxygen uptake (VO2), first and second ventilatory thresholds (VT1 and VT2, respectively), intensity corresponding to RER level of 1.0 (iRER1.0), peak velocity (PV), heart rate (HR), and rate of perceived exertion (RPE). One-way repeated measure analysis variance was used, following Bonferroni post hoc test. Agreement between parameters was evaluated by Pearson correlation and dispersion error. There were no significant differences between iRER1.0 and VT2 parameters. The correlations were significant between iRER1.0 and VT2 parameters for absolute and relative VO2, speed, and HR (r=0.95; r=0.60; r=0.72; r=0.81, respectively). A small mean error (-0.2 km·h-1) was observed between iRER1.0 and VT2. However, it was also observed an overestimation trend for high speeds. In conclusion, iRER1.0 can be used as an alternative method to detect AT in long distance runners. However, its use is limited in runners with high aerobic capacity

Effect of photobiomodulation therapy in the 1500 m run: An analysis of performance and individual responsiveness

Objective: The aims of this study were to verify the effects of photobiomodulation therapy (PBMT) on time trial run performance over 1500 m, as well as on individual responsiveness of recreative runners. Materials and methods: Nineteen recreationally trained runners participated in a randomized, crossover, double-blind placebo-controlled trial. The study was divided in four sessions: (1) incremental maximal running test; (2) 1500 m run control (without placebo or PBMT); and (3, 4) PBMT or placebo before 1500 m run. PBMT or placebo was applied over 14 sites per lower limb immediately before time trial run using a mixed wavelength device (33 diodes: 5 LASERs of 850 nm, 12 LEDs of 670 nm, 8 LEDs of 880 nm, and 8 LEDs with 950 nm). PBMT delivered 30 J per site, with a total energy dose of 840 J. Physiological variables [maximal oxygen uptake (VO2MAX), velocity associated to VO2MAX (vVO2MAX), peak of velocity, and respiratory compensation point (RCP)] were assessed during incremental maximal test. During 1500 m races we accessed the following: time, heart rate, and lower limb rate perception exertion per lap, total time, and blood lactate concentration ([Lac]). Results: PBMT had no significant difference and likely trivial effect for performance in the total time trial run over 1500 m compared to placebo. In the responsiveness analyses, 10 participants positively responded to PBMT, whereas total time reduced for responders (-10.6 sec; -3.18%) and increased for nonresponders (+6.0 sec; +1.73%). Responders presented higher aerobic parameters (VO2MAX and RCP) than nonresponders. Moreover, responders had lower time per lap and [Lac] (1 and 3 min) when PBMT was applied. Conclusions: PBMT applied immediately before running in noncontrolled environment was not able to improve the 1500 m performance of recreationally trained runners. However, responders to PBMT presented higher aerobic capacity than nonresponders.</p

Influence of Trunk Position during Three Lunge Exercises on Muscular Activation in Trained Women

International Journal of Exercise Science 14(1): 202-210, 2021. The present study aimed to compare the activation of the lower lumbar erector spinae, gluteus maximus, biceps femoris, and rectus femoris in two trunk positions (straight, and inclined) during three lunge exercises (static, step-forwarding, and walking) in trained young women in a randomized crossover design. Twelve women (24 ± 3 years) were selected and performed the lunge exercise with an overload of 30% of body weight in six conditions to analyze muscle activation via surface electromyography signals. Higher activation in the erector spinae (%MVIC) were observed (p \u3c 0.05) when trunk position was inclined (straight = 20 ± 15, inclined = 40 ± 29) and during the walking lunge condition (static = 24 ± 16, forward = 26 ± 22, walking = 40 ± 33). Higher activation in the gluteus maximus was observed during step-forward and walking lunges conditions (static = 31 ± 12, forward = 54 ± 20, walking = 58 ± 30). All conditions displayed similar activations in the biceps femoris and rectus femoris (p \u3e 0.05). Results indicate that positioning the trunk in a forward-inclined position induces greater lower lumbar erector spinae activation and dynamic lunge variations elicit greater muscular activation in the gluteus maximus than static lunges. Additionally, it seems that trunk and exercise variations do not influence the activation of tight muscles

Estimates of persistent inward currents increase with the level of voluntary drive in low-threshold motor units of plantar flexor muscles

This study tested whether estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. High-density surface electromyograms were collected from soleus and gastrocnemius medialis of 21 participants (29.2 ± 2.6 yr) during ramp-shaped isometric contractions to 10%, 20%, and 30% (torque rise and decline of 2%/s and 30-s duration) of each participant’s maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (DF) and estimate the PICs. DF is the difference in discharge rate of the control unit at the time of recruitment and derecruitment of the test unit. Increases in PICs were observed from 10% to 20% [D = 0.6 pulse per second (pps); P < 0.001] and from 20% to 30% (D = 0.5 pps; P < 0.001) in soleus and from 10% to 20% (D = 1.2 pps; P < 0.001) but not from 20% to 30% (D = 0.09 pps; P = 0.724) in gastrocnemius medialis. Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% [D = 1.75 pps (P < 0.001) and D = 2.43 pps (P < 0.001), respectively] and from 20% to 30% [D = 0.80 pps (P < 0.017) and D = 0.92 pps (P = 0.002), respectively]. The repeated-measures correlation identified associations between DF and increases in maximal discharge rate for soleus (r = 0.64; P < 0.001) and gastrocnemius medialis (r = 0.77; P < 0.001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or studies when relative force levels might be different. Increases in voluntary descending drive amplify PICs in humans and provide an important spinal mechanism for motor unit discharging, and thus force output modulation. NEW &amp; NOTEWORTHY Animal experiments and computational models have shown that motor neurons can amplify the synaptic input they receive via persistent inward currents. Here we show in humans that this amplification varies proportionally to the magnitude of the voluntary drive to the muscle.</p

Prediction of one repetition maximum for 45° leg press in untrained and trained elderly adults

The purpose of this study was to develop an equation to estimate maximum strength (1-RM) in elderly adults based on anthropometric and strength parameters. Initially, 20 subjects participated in the first equation (E1). Fifteen of the 20 completed the 12 wks of resistance training (RT). They were included in the second equation (E2). Anthropometric variables were measured pre- and post-intervention as were maximum dynamic strength (1-RM), number of repetitions (Reps), and Total Work (TW) of the maximum repetitions test (X-RM). The relationship between anthropometric, Reps, TW, and 1-RM were analyzed using Pearson's correlation. Backward multiple regression analyses were used to determine the independence and mutual contribution from anthropometric and X-RM parameters to predict 1-RM with P 2 = 0.896; P 2 = 0.830; P < 0.001). The findings can be used to safely determine 1-RM.</p